*-f'«
6ie'-"-' - . "#
tream
Corridor
Principles, Processes, and Practices
1952 Alignment
/ 1989 Restoration
-------
-------
Preface
"Water is the most critical resource issue of our lifetime
and our children's lifetime. The health of our waters is the
principal measure of how we live on the land"
Luna Leopold
Restoration practitioners share simultaneously in the good
fortune and responsibility of participating in a new endeavor
stepping beyond the current concept of natural resources
conservation to a newer concept of restoring the living
environment to an ecologically viable condition to create
places that improve rather than degrade over time. Oliver
Wendell Holmes once said, "A mind stretched by a new idea
can never go back to its original dimension."
This document is a result of an unprecedented cooperative
effort among fifteen Federal agencies and partners to produce
a common reference on stream corridor restoration. It responds
to a growing national and international public interest in
restoring stream corridors. Increasingly, feature articles, case
studies, and published papers focus on stream corridors as
critical ecosystems in our living environment. The recent
25th anniversary of the Clean Water Act also has helped focus
attention on stream corridor restoration.
This document encapsulates the rapidly expanding body of
knowledge related to stream corridors and their restoration.
It makes no endorsement of one particular approach to
restoration over another; nor is it intended as a policy document
of any participating Federal agency. It includes the full range of
possibilities facing restoration practitioners, including no action
or passive approaches, partial intervention for assisted recovery,
and substantial intervention for managed recovery.
The document encourages locally led, public involvement in
restoration planning and implementation. The challenges in
restoring thousands of miles of degraded stream corridors must
involve government agencies, public and private landowners,
permit holders, and local volunteer, civic, and conservation
groups and individuals.
We encourage users of this document to supplement it with new
literature, and regionally or locally specific information. You
will find this document on the Internet at http://www.usda.gov/
stream_restoration. We encourage restoration practitioners to
share new information and case studies with others to advance
the art and science of stream corridor restoration.
Preface
-------
We intend for the contents of this document to both entice
and challenge the reader by what they suggest not only work
to be studied and expanded, but work to be initiated.
The dedication of those who contributed to its production
will emerge on the landscape as restored, productive stream cor-
ridors, if the document provokes further interest, thought, and
continued cooperative action.
The Federal Interagency Stream
Restoration Working Group
Stream Corridor
-------
Contents
ACKNOWLEDGMENTS xix
INTRODUCTION 1-1
PART I: BACKGROUND
Chapter 1 Overview of Stream Corridors 1-1
1.A Physical Structure and Time at Multiple Scales 1 -3
Physical Structure 1 - 3
Structure at Scales Broader Than the Stream Corridor Scale 1-5
Regional Scale 1 - 6
Landscape Scale 1 - 7
"Watershed Scale" 1 - 8
Structure At the Stream Corridor Scale 1 - 10
Structure Within the Stream Corridor Scale 1 - 10
Temporal Scale 1-11
1.B A Lateral View Across the Stream Corridor 1 - 12
Stream Channel 1 - 12
Channel Size 1 - 13
Streamflow 1 - 14
Channel and Ground Water Relationships 1 - 15
Discharge Regime 1 - 16
Floodplain 1 - 18
Flood Storage 1 - 18
Landforms and Deposits 1 - 19
Transitional Upland Fringe 1 - 20
Vegetation Across the Stream Corridor 1 - 21
Flood-Pulse Concept 1 - 21
1.C A Longitudinal View Along the Stream Corridor 1-24
Longitudinal Zones 1 - 24
Watershed Forms 1 - 24
Drainage Patterns 1 - 25
Stream Ordering 1 - 25
Channel Form 1 - 26
Single-and Multiple-Thread Streams 1 -26
Sinuosity 1 - 27
Pools and Riffles 1 - 28
Vegetation Along the Stream Corridor 1 - 29
The River Continuum Concept 1 - 30
Contents iii
-------
Chapter 2: Stream Corridor Processes, Characteristics, and Functions 2-1
2.A Hydrologic and Hydraulic Processes 2-3
Hydrologic and Hydraulic Processes Across the Stream Corridor 2-4
Interception, Transpiration, and Evapotranspiration 2-4
Interception 2-4
Transpiration and Evapotranspiration 2-5
Infiltration, Soil Moisture, and Ground Water 2 - 7
Infiltration 2-7
Soil Moisture 2-9
Ground Water 2-10
Runoff 2-11
Overland Flow 2-11
Subsurface Flow 2-12
Saturated Overland Flow 2-13
Hydrologic and Hydraulic Processes Along the Stream Corridor 2-14
Flow Analysis 2-14
Ecological Impacts of Flow 2 - 15
2.B Geomorphic Processes 2-15
Geomorphic Processes Across the Stream Corridor 2-16
Geomorphic Processes Along the Stream Corridor 2-16
Sediment Transport 2-16
Sediment Transport Terminology 2-18
Stream Power 2-19
Stream and Floodplain Stability 2-20
Corridor Adjustments 2-21
Channel Slope 2-22
Pools and Riffles 2-22
Longitudinal Profile Adjustments 2-23
Channel Cross Sections 2-23
Resistance to Flow and Velocity 2-23
Active Channels and Floodplains 2-26
2.C Physical and Chemical Characteristics 2-26
Physical Characteristics 2-26
Sediment 2-26
Sediment Across the Stream Corridor 2-27
Sediment Along the Stream Corridor 2-28
Water Temperature 2-28
Water Temperature Across the Stream Corridor 2-28
Water Temperature Along the Stream Corridor 2-28
IV
Stream Corridor
-------
Chemical Constituents 2-28
ph, Alkalinity, and Acidity 2-30
ph, Alkalinity, and Acidity Across the Stream Corridor 2-30
ph, Alkalinity, and Acidity Along the Stream Corridor 2-31
Dissolved Oxygen 2-31
Dissolved Oxygen Across the Stream Corridor 2 - 32
Dissolved Oxygen Along the Stream Corridor 2-32
Nutrients 2-34
Nutrients Across the Stream Corridor 2-36
Nutrients Along the Stream Corridor 2-37
Toxic Organic Chemicals 2-38
Toxic Organic Chemicals Across the Stream Corridor 2-38
Toxic Organic Chemicals Along the Stream Corridor 2-38
Solubility 2-38
Sorption 2-40
Volatilization 2-42
Degradation 2-43
Toxic Concentrations of Bioavailab/e Metals 2-44
Toxic Concentrations of Bioavailable Metals Across
the Stream Corridor 2-44
Toxic Concentrations of Bioavailable Metals Along
the Stream Corridor 2-45
Ecological Functions of Soils 2-45
Soil Microbiology 2-46
Landscape and Topographic Position 2-47
Soil Temperature and Moisture Relationships 2-47
Wetland Soils 2-48
2.D Biological Community Characteristics 2-51
Terrestrial Ecosystems 2-51
Ecological Role of Soil 2-51
Terrestrial Vegetation 2-51
Landscape Scale 2-53
Stream Corridor Scale 2-53
Plant Communities 2-54
Terrestrial Fauna 2-56
Reptiles and Amphibians 2 - 57
Birds 2-57
Mammals 2-58
Aquatic Ecosystems 2-59
Aquatic Habitat 2-59
Wetlands 2-60
Aquatic Vegetation and Fauna 2-63
Contents
-------
Abiotic and Biotic Interrelations in the Aquatic System 2-67
Flow Condition 2-68
Water Temperature 2-68
Effects of Cover 2-68
Dissolved Oxygen 2-70
pH 2-71
Substrate 2-71
Organic Material 2-73
Terrestrial and Aquatic Ecosystem Components for
Stream Corridor Restoration 2-75
2.E Functions and Dynamic Equilibrium 2-78
Habitat Functions 2-80
Conduit Function 2-82
Filter and Barrier Functions 2-84
Source and Sink Functions 2-86
Dynamic Equilibrium 2-86
Chapter 3: Disturbance Affecting Stream Corridors 3-1
3.A. Natural Disturbances 3-3
3.B. Human-Induced Disturbances 3-6
Common Disturbances 3-7
Dams 3-7
Channelization and Diversions 3-8
Introduction of Exotic Species 3-10
Land Use Activities 3-14
Agriculture 3-14
Vegetative Clearing 3-14
Instream Modifications 3-14
Soil Exposure and Compaction 3-15
Irrigation and Drainage 3-15
Sediment and Contaminants 3-15
Forestry 3-16
Removal of Trees 3-16
Transportation of Products 3-17
Site Preparation 3-17
Domestic Livestock Grazing 3-18
Loss of Vegetative Cover 3-18
Physical Impacts from Livestock Presence 3-19
Mining 3-19
Vegetative Clearing 3-20
Soil Disturbance ., .3-20
vi Stream Corridor
-------
.. , , ,
Altered Hydrology 3-20
Contaminants 3-21
Recreation 3-21
Urbanization 3-22
Altered Hydrology 3-23
Altered Channels 3-24
Sedimentation and Contaminants 3-24
Habitat and Aquatic Life 3-25
Summary of Potential Effects of Land Use Activities 3-26
PART II: DEVELOPING A RESTORATION PLAN
Chapter 4: Getting Organized and Identifying Problems
and Opportunities 4-1
4.A Getting Organized 4-3
Setting Boundaries 4-3
Forming an Advisory Group 4-4
Establishing Technical Teams 4-5
Identifying Funding Sources 4-9
Establishing a Decision Structure and Points of Contact 4-10
Facilitating Involvement and Information Sharing Among Participants 4-10
Receiving Input from Restoration Participants 4-10
Informing Participants Throughout the Restoration Process 4- 12
Selecting Tools for Facilitating Information Sharing
and Participant Involvement 4-13
Documenting the Process 4-13
4.B Problem and Opportunity Identification 4-16
Data Collection and Analysis 4-16
Data Collection 4-16
Collecting Baseline Data 4-16
Collecting Historical Data 4-16
Collecting Social, Cultural, and Economic Data 4-18
Prioritizing Data Collection 4-18
Data Analysis 4-19
Existing Stream Corridor Structure, Functions, and Disturbances 4-19
Existing vs. Desired Structure and Functions: The Reference Condition 4-20
Causes of Altered or Impaired Conditions 4-23
Landscape Factors Affecting Stream Corridor Condition 4-23
Stream Corridor and Reach Factors Affecting Stream
Corridor Conditions 4-25
Determination of Management Influence on Stream Corridor Conditions .. 4-26
Problem or Opportunity Statements for Stream Corridor Restoration 4-27
Contents vii
-------
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives 5-1
5.A Developing Restoration Goals and Objectives 5-3
Defining Desired Future Stream Corridor Conditions 5-3
Identifying Scale Considerations 5-3
The Landscape Scale 5-5
Regional Economic and Natural Resource
Management Considerations 5-5
Land Use Considerations 5-5
Biodiversity Considerations 5-6
The Stream Corridor Scale 5-6
The Reach Scale 5-7
Identifying Restoration Constraints and Issues 5-7
Technical Constraints 5-8
Quality Assurance, Quality Control 5-8
Nontechnical Constraints 5-9
Land and Water Use Conflicts 5-9
Financial Issues 5-9
Institutional and Legal Issues 5-11
Defining Restoration Goals 5-12
Considering Desired Future Condition 5-12
Factoring In Constraints and Issues 5-12
Defining Primary and Secondary Restoration Goals 5-12
Primary Restoration Goals 5-13
Secondary Restoration Goals 5-13
Defining Restoration Objectives 5-13
5.B Alternative Selection and Design 5-17
Important Factors to Consider in Designing Restoration Alternatives 5-17
Managing Causes vs. Treating Symptoms 5-17
Landscape/Watershed vs. Corridor/Reach 5-19
Other Time and Space Considerations 5-20
Supporting Analysis for Selecting Restoration Alternatives 5-21
Cost-Effectiveness and Incremental Cost Analysis 5-21
Data Requirements: Solutions, Costs, and Outputs 5-21
Cost-Effectiveness Analysis 5-26
Incremental Cost Analysis 5-27
Decision Making"Is It Worth It?" 5-28
Evaluation of Benefits 5-29
Risk Assessment 5-29
Environmental Impact Analysis 5-30
viii Stream Corridor
-------
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting 6-1
6.A Restoration Implementation 6-2
Securing Funding for Restoration Implementation 6-2
Identifying Tools to Facilitate Restoration Implementation 6-3
Dividing Implementation Responsibilities 6-4
Identifying the Players 6-4
Assigning Responsibilities 6-6
Interdisciplinary Technical Team 6-8
Volunteers 6-8
Contractors 6-10
Securing Commitments 6-10
Installing Restoration Measures 6-11
Determining the Schedule 6-12
Obtaining the Necessary Permits 6-13
Holding Pre-installation Conferences 6-14
Involving Property Owners 6-15
Securing Site Access 6-15
Locate Existing Utilities 6-16
Confirming Sources and Ensuring Materials Standards 6- 17
Characteristics of Successful Implementation 6-17
Central Responsibility in One Person 6-17
Thorough Understanding of Planning and Design Materials 6-20
Familiarity with the Reach 6-20
Knowledge of Laws and Regulations 6-21
Understanding of Environmental Control Plans 6-21
Communication Among All Parties Involved in the Action 6-21
6.B Restoration Monitoring, Evaluation, and Adaptive Management 6-22
Monitoring As Part of a Stream Corridor Restoration Initiative 6-22
Components of a Monitoring Plan 6-23
When to Develop the Monitoring Plan 6-24
Developing a Monitoring Plan 6-24
Step 1: Define The Restoration Vision, Goals, Objectives 6-24
Step 2: Develop The Conceptual Model 6-24
Sfep 3: Choose Performance Criteria 6-24
Link Performance to Goals 6-24
Develop the Criteria 6-26
Identify Reference Sites 6-26
Sfep 4: Choose Monitoring Parameters And Methods 6-26
Choose Efficient Monitoring Parameters 6-27
Review Watershed Activities 6-27
Choose Methods for Sampling Design, Sampling, and Sample
Handling and Processing 6-28
Contents ix
-------
Conduct Sociological Surveys 6-28
Rely on Instream Organisms for Evidence of Project Success 6-28
Minimize the Necessary Measurements of Performance 6-29
Incorporate Supplemental Parameters 6-29
Step 5: Estimate Cost 6-29
Step 6: Categorize The Types Of Data 6-31
Step 7: Determine The Level Of Effort And Duration 6-31
Incorporate Landscape Ecology 6-31
Determine Timing, Frequency, and Duration of Sampling 6-32
Develop a Statistical Framework 6-33
Choose the Sampling Level 6-33
Implementing and Managing the Monitoring Plan 6-33
Envisioning the Plan 6-34
Determining Roles 6-34
Ensuring Quality 6-34
Interpreting Results 6-34
Managing Data 6-34
Managing Contracts 6-34
Restoration Evaluation 6-34
Reasons to Evaluate Restoration Efforts 6-35
Protecting the Restoration Investment 6-35
Helping to Advance Restoration Knowledge for Future Applications .... 6-36
Maintaining Accountability to Restoration Supporters 6-36
Acting on the Results 6-36
Alternative Actions 6-37
Adaptive Management 6-37
Documenting and Reporting 6-38
Dissemination of the Results 6-39
Planning for Feedback During Restoration Implementation 6-39
Making a Commitment to the Time Frame Needed to Judge Success .. 6-39
Evaluating Changes in the Sources of Stress
as Well as in the System Itself 6-41
PART III: APPLYING RESTORATION PRINCIPLES
Chapter 7: Analysis of Corridor Condition 7-1
7.A Hydrologic Processes 7-3
Flow Analysis 7-3
Flow Duration 7-3
Flow Frequency Analysis 7-4
Flood Frequency Analysis 7-4
Low-flow Frequency Analysis 7-7
Channel Forming Flow 7-8
Bankfull Discharge 7-10
Field Indicators of Bankfull Discharge 7-10
Stream Corridor
-------
Determining Channel Forming Discharge from Recurrence Interval 7-12
Effective Discharge 7-13
Determining Channel-Forming Discharge from
Other Watershed Variables 7-15
Mean Annual Flow 7-15
Stage-Discharge Relationships 7-17
Continuity Equation 7-17
Manning's Equation 7-17
Direct Solution for Manning's n 7- 18
Using Manning's n Measured at Other Channels 7-19
Energy Equation 7-21
Analyzing Composite and Compound Cross Sections 7-23
Reach Selection 7-23
Field Procedures 7-24
Survey of Cross Section and Water Surface Slope 7-24
Bed Material Particle Size Distribution 7-25
Discharge Measurement 7-25
7.B Geomorphic Processes 7-26
Stream Classification 7-26
Advantages of Stream Classification Systems 7-27
Limitations of Stream Classification Systems 7-27
Stream Classification Systems 7 - 28
Stream Order 7-28
Schumm 7-29
Montgomery and Buffington 7-29
Rosgen Stream Classification System 7-29
Channel Evolution Models 7-30
Advantages of Channel Evolution Models 7-34
Limitations of Channel Evolution Models 7-36
Applications of Geomorphic Analysis 7-37
Proper Functioning Condition (PFC) 7-39
Hydraulic Geometry: Streams in Cross Section 7-41
Hydraulic Geometry and Stability Assessment 7-44
Regional Curves 7-44
Planform and Meander Geometry: Stream Channel Patterns 7-47
Stream System Dynamics 7-48
Determining Stream Instability: Is It Local or Systemwide? 7-50
Systemwide Instability 7-51
Local Instability 7-51
Bed Stability 7-51
Specific Gage Analysis 7-52
Comparative Surveys and Mapping 7-53
Regression Functions for Degradation 7-54
Regression Functions for Aggradation 7-55
Contents xi
-------
Sediment Transport Processes 7 - 57
Numerical Analyses and Models to Predict Aggradation
and Degradation 7-57
Bank Stability 7-57
Qualitative Assessment of Bank Stability 7-57
Quantitative Assessment of Bank Stability 7-59
Bank Instability and Channel Widening 7-60
Bank Stability Charts 7-60
Predictions of Bank Stability and Channel Width 7-62
7.C Chemical Characteristics 7-63
Data Collection 7-63
Constituent Selection 7-63
Sampling Frequency 7-63
Site Selection 7-64
Sampling Techniques 7-64
Sampling Protocols for Water and Sediment 7-65
Manual Sampling and Grab Sampling 7-65
Automatic Sampling 7-65
Discrete vs. Composite Sampling 7-66
Field Analyses of Water Quality Samples 7-67
pH 7-68
Temperature 7-68
Dissolved Oxygen 7-68
Water Quality Sample Preparation and Handling for
Laboratory Analysis 7-69
Sample Preservation, Handling, and Storage 7-69
Sample Labeling 7-69
Sample Packaging and Shipping 7-70
Chain of Custody 7-70
Collecting and Handling Sediment Quality Samples 7-70
Collection Techniques 7-71
Sediment Analysis 7 - 71
Data Management 7-72
Quality Assurance and Quality Control (QA/QC) 7-73
Sample and Analytical Quality Control 7-73
Field Quality Assurance 7-74
7.D Biological Characteristics 7-75
Synthetic Measures of System Condition 7-75
Indicator Species 7-76
The Good and Bad of Indicator Species 7-76
Selecting Indicators 7-77
Riparian Response Guilds 7-78
Aquatic Invertebrates 7-78
xii Stream Corridor
-------
Diversity and Related Indices 7-78
Level of Complexity 7-79
Subsets of Concern 7-79
Spatial Scale 7-79
Measures of Diversity 7-79
Related Integrity Indices 7-80
Rapid Bioassessment 7-80
Algae 7-81
Benthic Macroinvertebrates 7-82
Fish 7-83
Establishing a Standard of Comparison 7-83
Evaluating the Chosen Index 7-84
Classification Systems 7-85
Use of Classification Systems in Restoring Biological Conditions .... 7-86
Analysis of Species Requirements 7-86
The Habitat Evaluation Procedures (HEP) 7-87
Basic Concepts 7-87
Use of HEP to Assess Habitat Changes 7-88
Instream Flow Incremental Methodology 7-88
Physical Habitat Simulation 7-88
Two-dimensional Flow Modeling 7-90
Riverine Community Habitat Assessment and Restoration
Concept Model (RCHARC) 7-91
Time Series Simulations 7-91
Individual-based Models 7-92
SALMOD 7-93
Vegetation-Hydroperiod Modeling 7-94
Components of a Vegetation-hydroperiod Model 7-94
Identifying Non-equilibrium Conditions 7-95
Vegetation Effects of System Alterations 7-95
Extreme Events and Disturbance Requirements 7-96
ChapterS: Restoration Design 8-1
8.A Valley Form, Connectivity, and Dimension 8-4
Valley Form 8-4
Stream Corridor Connectivity and Dimension 8-4
Cognitive Approach: The Reference Stream Corridor 8-7
Analytical Approach: Functional Requirements of a Target Species .... 8-7
Designing for Drainage and Topography 8-8
8.B Soil Properties 8-8
Compaction 8-9
Soil Microfauna 8-9
Soil Salinity 8-10
Contents xiii
-------
8.C Plant Communities 8-10
Riparian Buffer Strips 8-11
Existing Vegetation 8-11
Plant Community Restoration 8-14
Horizontal Diversity 8-17
Connectivity and Gaps 8-17
Boundaries 8-20
Vertical Diversity 8-21
Influence of Hydrology and Stream Dynamics 8-22
Soil Bioengineering for Floodplains and Uplands 8-23
8.D Habitat Measures 8-24
Greentree Reservoirs 8-24
Nest Structures 8-25
Food Patches 8-25
8.E Stream Channel Restoration 8-28
Procedures for Channel Reconstruction 8-28
Alignment and Average Slope 8 - 31
Channel Dimensions 8-32
Reference Reaches 8-33
Application of Regime and Hydraulic Geometry Approaches 8-36
Analytical Approaches for Channel Dimensions 8-37
Tractive Stress (No Bed Movement) 8-38
Channels with Moving Beds and Known Slope 8-38
Channels with Moving Beds and Known Sediment Concentration 8-39
Use of Channel Models for Design Verification 8-40
Physical Models 8-41
Computer Models 8-41
Detailed Design 8-43
Channel Shape 8-43
Channel Longitudinal Profile and Riffle Spacing 8-43
Stability Assessment 8-44
Vertical (Bed) Stability 8-44
Horizontal (Bank) Stability 8-45
Bank Stability Check 8-46
Allowable Velocity Check 8-48
Allowable Stress Check 8-48
Practical Guidance: Allowable Velocity and Shear Stress 8-51
Allowable Stream Power or Slope 8-52
Sediment Yield and Delivery 8-53
Sediment Transport 8-53
Sediment Discharge Functions 8-55
Sediment Budgets 8-56
Example of a Sediment Budget 8-56
xiv Stream Corridor
-------
Single Storm Versus Average Annual Sediment Discharge 8-58
Sediment Discharge After Restoration 8-60
Stability Controls 8-60
8.F Streambank Restoration 8-61
Effectiveness of Technique 8-62
Stabilization Techniques 8-64
Anchored Cutting Systems 8-64
Geotextile Systems 8-65
Integrated Systems 8-66
Trees and Logs 8-66
8.G In-Stream Habitat Recovery 8-70
In-Stream Habitat Features 8-71
In-Stream Habitat Structures 8-72
In-Stream Habitat Structure Design 8-72
Plan Layout 8-73
Select Types of Structures 8-73
Size the Structures 8-74
Investigate Hydraulic Effects 8-74
Consider Effects on Sediment Transport 8-74
Select Materials 8-74
8.H Land Use Scenarios 8-76
Design Approaches for Common Effects 8-77
Dams 8-77
Channelization and Diversions 8-79
Exotic Species 8-79
Agriculture 8-83
Hypothetical Exiting Conditions 8-83
Hypothetical Restoration Response 8-84
Forestry 8-86
Forest Roads 8-88
Buffer Strips in Forestry 8-89
Grazing 8-90
Mining 8-96
Recreation 8-97
Urbanization 8-97
Key Tools of Urban Stream Restoration Design 8- 101
Chapter 9: Restoration Implementation, Monitoring, and Management 9-1
9.A Restoration Implementation 9-3
Site Preparation 9-3
Delineating Work Zones 9-3
Contents xv
-------
Preparing Access and Staging Areas 9-4
Taking Precautions to Minimize Disturbance 9-4
Protection of Existing Vegetation and Sensitive Habitat 9-4
Erosion 9-4
Water Quality 9-6
Air Quality 9-7
Cultural Resources 9-8
Noise 9-8
Solid Waste Disposal 9-9
Worksite Sanitation 9-9
Obtaining Appropriate Equipment 9-9
Site Clearing 9-10
Geographic Limits 9-10
Removal of Undesirable Plant Species 9- 10
Drainage 9-11
Protection and Management of Existing Vegetation 9- 12
Installation and Construction 9-12
Earth Moving 9-12
Fill Placement and Disposal 9-12
Contouring 9-13
Final Grading 9-14
Diversion of Flow 9-14
Installation of Plant Materials 9-15
Timing 9-16
Acquisition 9-16
Transportation and Storage 9-16
Planting Principles 9-17
Competing Plants 9-18
Use of Chemicals 9-18
Mulches 9-19
Irrigation 9-20
Fencing 9-20
Inspection 9-21
On-Site Inspection Following Installation 9-22
Follow-up Inspections 9-22
General Inspection 9-23
Bank and Channel Structures 9-23
Vegetation 9-24
Urban Features 9-25
Maintenance 9-26
Channels and Floodplains 9-27
Protection/Enhancement Measures 9-27
Vegetation 9-28
Other Features . .9-28
xvi Stream Corridor
-------
9.B Monitoring Techniques Appropriate for Evaluating Restoration 9-29
Adaptive Management 9-32
Implementation Monitoring 9-32
Effectiveness Monitoring 9-32
Validation Monitoring 9-32
Evaluation Parameters 9-32
Physical Parameters 9-32
Biological Parameters 9-33
Chemical Parameters 9-33
Reference Sites 9-35
Human Interest Factors 9-38
9.C Restoration Management 9-40
Streams 9-41
Forests 9-42
Grazed Lands 9-43
Fish and Wildlife 9-46
Human Use .. .9-46
APPENDICES
Appendix A: Techniques A - 1
Appendix B: U.S./Metric Conversion Factors A - 31
ADDENDUM
References B - 1
Index . B - 33
Contents xvii
-------
XVIII
Stream Corridor
-------
Acknowledgments
Machines printed this document, but people translated their collective knowledge
and experience into the printed word. The following agencies, people, and
affiliates cooperated and worked together to produce the interagency document,
"Stream Corridor Restoration: Principles, Processes, and Practices." Numerous
other people also worked in support or consultative roles within and outside of
the agencies, and their contribution is acknowledged and very much appreciated.
Federal Agencies
The following federal agencies collaborated to produce this document:
U.S. Department of Agriculture
Agricultural Research Service
Cooperative State Research, Education, and Extension Service
Forest Service
Natural Resources Conservation Service
U.S. Environmental Protection Agency
Tennessee Valley Authority
Federal Emergency Management Agency
U.S. Department of Commerce
National Oceanographic and Atmospheric Administration
- National Marine Fisheries Service
U.S. Department of Defense
Army Corps of Engineers
U.S. Department of Housing and Urban Development
U.S. Department of the Interior
Bureau of Land Management
Bureau of Reclamation
Fish and Wildlife Service
National Park Service
U.S. Geological Survey
These federal agencies produced this document with their resources
and human talent, forming and supporting a Production Team,
a Communications Team, and a Steering Team.
Acknowledgements xix
-------
Production Team
The Production Team developed much of the material for this document.
Some individuals on this team led the development of individual chapters and
wrote specific parts of the document. Contributing authors include recognized
experts from universities and consulting firms.
Name
Adams, Carolyn
Allen, Hollis
Bates, A. Leon
Booth, Derek
Cleveland, Mark
Corry, Rob
Croft, Richard
Fairchild, Jim
Fogg, Jim*
Jim Golden
Gray, Randall
Hollins, Michael
Homa, John
Jackson, John K.
Johnson, R. Roy
Kelley, Kenneth R.
Klimas, Charles
Landin, Mary
McCardle, Kevin
Potts, Donald F.
Saele, Leland
Scheyer, Joyce Mack
Shepherd, Jennifer
Shields, Jr., F. Douglas
Steffen, Lyle
Sullivan, Marie
Thomas, Wilbert 0.
Wells, Gary*
Wesche, Tom
Willard, Daniel E.
Affiliation
USDA-Natural Resources Conservation Service,
Watershed Science Institute
U.S. Army Corps of Engineers, Waterways Experiment Station
Tennessee Valley Authority
Center for Urban Water Resources Management, U. of Washington
USDA-Forest Service
Environmental Alliance for Senior Involvement
USDA-Natural Resources Conservation Service
USDI-U.S. Geological Survey-BRD, Environ, and
Contaminants Research Ctr.
USDI-Bureau of Land Management
USDA-Forest Service
USDA-Natural Resources Conservation Service
Ecosystem Recovery Institute
Ichthyological Associates, Inc.
Stroud Water Research Center
Johnson & Haight Environmental Consultants
Tennessee Valley Authority
Charles Klimas & Associates, Inc.
U.S. Army Corps of Engineers, Waterways Experiment Station
Environmental Alliance for Senior Involvement
School of Forestry, U. of MT
USDA-Natural Resources Conservation Service
USDA-Natural Resources Conservation Service
Environmental Alliance for Senior Involvement
USDA-Agricultural Research Service, ARS National Sedimentation Lab.
USDA-Natural Resources Conservation Service
USDI-Fish and Wildlife Service
Michael Baker Jr., Inc.
USDA-Natural Resources Conservation Service
Wyoming Water Resources Center, University of Wyoming
School of Public & Environmental Affairs, Indiana University
Location
Portland, OR
Vicksburg, MS
Muscle Shoals, AL
Seattle, WA
Aberdeen, MD
Washington, DC
Burlington, VT
Columbia, MO
Denver, CO
Bend, OR
Ft. Worth, TX
Freeland, MD
Ithaca, NY
Avondale, PA
Muscle Shoals, AL
Seattle, WA
Vicksburg, MS
Washington, DC
Portland, OR
Lincoln, NE
Washington, DC
Oxford, MS
Lincoln, NE
Sacramento, CA
Alexandria, VA
Lincoln, NE
Laramie, WY
Bloomington, IN
*Co-leader, Production Team
XX
Stream Corridor
-------
Communications Team
The Communications Team developed the plan for promoting the creation of
this document, both in process and product. Members designed and produced
a variety of information materials for people interested in the document.
Name
Becker, Hank
Davidek, June*
Dawson, Michelle
Forshee, Carol
Hewitt, Dave
Icke, Tim
Meeks, Tim
Munsey, Tom
O'Connor, Mike
Rieben, Craig
Tennyson, Janet
White, David
Affiliation
USDA-Agricultural Research Service
USDA-Natural Resources Conservation Service
USDI-Bureau of Land Management
U.S. Environmental Protection Agency
U.S. Army Corps of Engineers
U.S. Environmental Protection Agency
Tennessee Valley Authority
U.S. Army Corps of Engineers
USDA-Forest Service
USDI-Fish and Wildlife Service
USDI-Fish and Wildlife Service
USDA-Natural Resources Conservation Service
Location
Greenbelt, MD
Washington, DC
Washington, DC
Washington, DC
Washington, DC
Washington, DC
Muscle Shoals, AL
Washington, DC
Washington, DC
Washington, DC
Washington, DC
Washington, DC
"Leader, Communications Team
Acknowledgements
XXI
-------
Steering Team
The Steering Team organized, led, and coordinated the production of this docu-
ment. Steering Team members not only represented the interests of their agen-
cies but also served as contact pivots for information to and from their agencies
and also wrote parts of the document. The Steering Team also secured
nonfederal peer review of this document and facilitated the signing of the
Memorandum of Understanding.
Name Affiliation Location
Bernard, Jerry** USDA-Natural Resources Conservation Service Washington, DC
Bornholdt, Dave USDI-U.S. Geological Survey Reston, VA
Brady, Don U.S. Environmental Protection Agency Washington, DC
Burns, Meg J. U.S. Army Corps of Engineers Baltimore, MD
Cope, Gene National Oceanic and Atmospheric Administration, Washington, DC
National Marine Fisheries Service, Office of Habitat Conservation
Cunniff, Shannon USDI-Bureau of Reclamation Washington, DC
DiBuono, Richard U.S. Army Corps of Engineers Washington, DC
Euston, Andrew Department of Housing and Urban Development Washington, DC
Farrell, David A. USDA-Agricultural Research Service Beltsville, MD
Getzen, Beverley U.S. Army Corps of Engineers Washington, DC
Gray, John USDI-U.S. Geological Survey Reston, VA
Horton, Denise USDA-Natural Resources Conservation Service Chattanooga, TN
Kelley, Kenneth R. Tennessee Valley Authority Muscle Shoals, AL
Kliwinski, Sharon USDI-National Park Service Washington, DC
LaFayette, Russell USDA-Forest Service Washington, DC
McShane, John Federal Emergency Management Agency Washington, DC
Miller, James E. USDA-Cooperative State Research, Education, and Extension Service Washington, DC
Munsey, Tom U.S. Army Corps of Engineers Washington, DC
Nolton, Darrell U.S. Army Corps of Engineers Alexandria, VA
Norton, Doug U.S. Environmental Protection Agency Washington, DC
Robinson, Mike Federal Emergency Management Agency Washington, DC
Rylant, Karen E. Tennessee Valley Authority Muscle Shoals, AL
Schilling, Kyle U.S. Army Corps of Engineers Ft. Belvoir, VA
Schmidt, Larry USDA-Forest Service Ft. Collins, CO
Smalley, Dan USDI-Fish and Wildlife Service Arlington, VA
Stabler, Fred USDI-Bureau of Land Management Washington, DC
Tuttle, Ron** USDA-Natural Resources Conservation Service Washington, DC
**Co-leader, Steering Team
XXII
Stream Corridor
-------
Design and Printing Team
The Design and Printing Team members revised working and review drafts for
agency and peer comment. Several agency staffs developed the final product
layout, design, and printing.
Name
Bartow, Sue
Bernard, Jerry
Butcher, John
Cauley, Shannon
Corry, Rob
Creager, Clayton
Fogg, Jim
Gleeson, Lisa**
Grimm, Sandy
Gunning, Paul
Hiett, Liz
Hill, Linda*
Cuffe, Kelly
McCardle, Kevin
Martin, Marti
Meyer, Mary
Olson, Julie**
Pett, Sam
Proctor, Paula
Shepherd, Jennifer
Simpson, Jonathan*
Sutton, David**
Tuttle, Ron
Randy Varney
Wells, Gary
Affiliation
Tetra Tech, Inc.
USDA-Natural Resources Conservation Service
Tetra Tech, Inc.
Tetra Tech, Inc.
Environmental Alliance for Senior Involvement
Tetra Tech, Inc.
USDI-Bureau of Land Management
U.S. Department of Agriculture
USDA-Natural Resources Conservation Service
Tetra Tech, Inc.
Tetra Tech, Inc.
USDI-Bureau of Land Management
Tetra Tech, Inc.
Environmental Alliance for Senior Involvement
Tetra Tech, Inc.
USDA-Natural Resources Conservation Service
U.S. Department of Agriculture
Tetra Tech, Inc.
Tetra Tech, Inc.
Environmental Alliance for Senior Involvement
Tetra Tech, Inc.
U.S. Department of Agriculture
USDA-Natural Resources Conservation Service
Tetra Tech, Inc.
USDA-Natural Resources Conservation Service
Location
Fairfax, VA
Washington, DC
Research Triangle Park, NC
Fairfax, VA
Washington, DC
Calistoga, CA
Denver, CO
Washington, DC
Washington, DC
Fairfax, VA
Fairfax, VA
Denver, CO
San Francisco, CA
Washington, DC
Fairfax, VA
Bozeman, MT
Washington, DC
Fairfax, VA
Fairfax, VA
Washington, DC
Fairfax, VA
Washington, DC
Washington, DC
San Francisco, CA
Lincoln, NE
*Editor
**Layout, Design, and Printing
Nongovernmental Organizations
The World Wildlife Fund coordinated input and reviews from other
nongovernmental organizations.
Name
Hunt, Constance
Affiliation
World Wildlife Fund
Location
Washington, DC
Acknowledgements
XXIII
-------
Peer Review
In addition to internal agency reviews, an independent peer review panel coor-
dinated external reviews.
Name
Clar, Michael L.
Erickson, Nancy
Herrick, Edwin
Hill, Kristina E.
Hunt, Constance
Ice, Dr. George
Leighton, Elizabeth
Litjens, Gerard
Louthain, Jerry
Mclsaac, Greg
Neil, C. R.
Patten, Dr. Duncan
Rast, Georg
Reckendorf, Frank
Riley, Ann
Roseboom, Donald
Rosgen, Dave
Schueler, Thomas
Sotir, Robbin B.
Affiliation
Engineering Technologies Associates, Inc.
Illinois Farm Bureau
University of Illinois
Department of Landscape Architecture, U. of Washington
World Wildlife Fund
National Council for Air & Stream Improvement
WWF Wild Rivers Institute
Foundation Ark
Washington State Department of Ecology
University of Illinois, Ag. Engineering Dept.
Northwest Hydraulic Consultants, Ltd.
Society of Wetland Scientists
WWF Floodplain Ecology Institute
Reckendorf and Associates
Waterways Restoration Institute
Illinois State Water Survey
Wildland Hydrology
Center for Watershed Protection
Robbin B. Sotir & Associates
Location
Ellicott City, MD
Peoria, IL
Urbana-Champaign, IL
Seattle, WA
Washington, DC
Corvallis, OR
Scotland
Netherlands
Olympia, WA
Urbana-Champaign, IL
Edmonton, Alberta, Canada
Bozeman, MT
Rastatt, Germany
Salem, OR
Berkeley, CA
Peoria, IL
Pagosa Springs, CO
Ellicott City, MD
Marietta, GA
XXIV
Stream Corridor
-------
Other Contributors
Other invaluable support and assistance was rendered by
numerous individuals, including:
Name
Alonso, Carlos V.
Andrews, Ned
Biedenharn, David
Bingner, Ronald L.
Briggs, Mark
Broshears, Bob
Cannell, John
Clark, Jerry
Copeland, Ronald
Coreil, Paul D.
Corrigan, Mary Beth
Darby, Stephen E.
Davenport, Tom
Eddy-Miller, Cheryl
Fischenich, Craig
Hankin, Howard
Jackson, William L.
Hughey, William
Ischinger, Lee
Klofstad, Gordon
Krueper, David
Kuhnle, Roger A.
Labaugh, Jim
Levish, Dan
Martin, Krtsten
Miller, Clint
Morganwalp, David
Petri, Mark
Ratcliffe, Susan
Simon, Andrew
Stockman, Charlie
Sumner, Richard
Taylor, Theresa
Troast, Judy
Wittier, Rodney J.
Woodward, Don
Yang, C. Ted
Zabawa, Chris
Affiliation
USDA-Agricultural Research Service
U.S. Geological Survey
U.S. Army Corps of Engineers
USDA-Agricultural Research Service
Rincon Institute
U.S. Geological Survey
U.S. Environmental Protection Agency
National Fish and Wildlife Foundation
U.S. Army Corps of Engineers
Louisiana State University
Tetra Tech, Inc.
USDA-Agricultural Research Service
U.S. Environmental Protection Agency
U.S. Geological Survey
U.S. Army Corps of Engineers
USDA-Natural Resources Conservation Service
USDI-National Park Service
USDA-Natural Resources Conservation Service
Midcontinental Ecological Science Center
USDA-Natural Resources Conservation Service
USDI-Bureau of Land Management
USDA-Agricultural Research Service
U.S. Geological Survey
USDI-Bureau of Reclamation
U.S. Environmental Protection Agency
City of Boulder
U.S. Geological Survey
School of Natural Resources, U. of MO
U.S. Environmental Protection Agency
USDA-Agricultural Research Service
USDI-National Park Service
U.S. Environmental Protection Agency
USDI-Bureau of Reclamation
USDI-Bureau of Reclamation
USDI-Bureau of Reclamation
USDA-Natural Resources Conservation Service
USDI-Bureau of Reclamation
U.S. Environmental Protection Agency
Location
Oxford, MS
Boulder, CO
Vicksburg, MS
Oxford, MS
Tucson, AZ
Lakewood, CO
Washington, DC
Washington, DC
Vicksburg, MS
Baton Rouge, LA
Fairfax, VA
Oxford, MS
Chicago, IL
Cheyenne, WY
Vicksburg, MS
Washington, DC
Fort Collins, CO
Washington, DC
Ft. Collins, CO
Washington, DC
Sierra Vista, AZ
Oxford, MS
Reston, VA
Denver, CO
Washington, DC
Boulder, CO
Reston, VA
Columbia, MO
Washington, DC
Oxford, MS
Washington, DC
Corvalis, OR
Denver, CO
Washington, DC
Denver, CO
Washington, DC
Denver, CO
Washington, DC
Acknowledgements
xxv
-------
-------
Overview of
Stream
Corridors
-------
1.A Overview of Structure and Scale
What are the structural components of a stream corridor?
Why are stream corridors of special significance, and why should they be the focus of
restoration efforts?
What is the relationship between stream corridors and other landscape units at broader and
more local scales?
What scales should be considered for a stream corridor restoration?
1.B Stream Corridor Functions and Dynamic Equilibrium
How is a stream corridor structured from side to side?
How do these elements contribute to stream corridor functions?
What role do these elements play in the life of the stream?
What do we need to know about the lateral elements of a stream corridor to adequately
characterize a stream corridor for restoration?
How are the lateral elements of a stream corridor used to define flow patterns of a stream?
1.C A Longitudinal View Along the Stream Corridor
What are the longitudinal structural elements of a stream corridor?
How are these elements used to characterize a stream corridor?
What are some of the basic ecological concepts that can be applied to streams to understand
their function and characteristics on a longitudinal scale?
What do we need to know about the longitudinal elements that are important to stream
corridor restoration?
-------
Stream
Corridor
Restoration:
Principles,
Processes,
and Practices
Introduction
There is a phenomenal resiliency
in the mechanisms of the earth.
A river or lake is almost never
dead. If you give it the slightest
chance...then nature usually
comes back.
Rene Dubos 1981
Why Is Stream Corridor Restoration
Important?
The United States has more than 3.5 million
miles of rivers and streams that, along with
closely associated floodplain and upland areas,
comprise corridors of great economic, social,
cultural, and environmental value. These corri-
dors are complex ecosystems that include the
land, plants, animals, and network of streams
within them. They perform a number of eco-
logical functions such as modulating stream-
flow, storing water, removing harmful materials
from water, and providing habitat for aquatic
and terrestrial plants and animals. Stream corri-
dors also have vegetation and soil characteris-
tics distinctly different from surrounding
uplands and support higher levels of species
diversity, species densities, and rates of biologi-
cal productivity than most other landscape
elements.
Streams and stream corridors evolve in concert
with and in response to surrounding ecosystems.
Changes within a surrounding ecosystem (e.g.,
watershed) will impact the physical, chemical,
and biological processes occurring within a
stream corridor. Stream systems normally func-
tion within natural ranges of flow, sediment
movement, temperature, and other variables, in
what is termed "dynamic equilibrium." When
changes in these variables go beyond their nat-
ural ranges, dynamic equilibrium may be lost,
often resulting in adjustments in the ecosystem
that might conflict with societal needs. In some
circumstances, a new dynamic equilibrium may
Fig. 1.1: Stream corridor in the
Midwest. Stream corridors have
great economic, social, cultural,
and environmental values.
-------
eventually develop, but the time frames
in which this happens can be lengthy,
and the changes necessary to achieve this
new balance significant.
Over the years, human activities have
contributed to changes in the dynamic
equilibrium of stream systems across
the nation. These activities center on
manipulating stream corridor systems
for a wide variety of purposes, includ-
ing domestic and industrial water sup-
plies, irrigation, transportation,
hydropower, waste disposal, mining,
flood control, timber management,
recreation, aesthetics, and more re-
cently, fish and wildlife habitat. In-
creases in human population and
industrial, commercial, and residential
development place heavy demands on
this country's stream corridors.
The cumulative effects of these activities
result in significant changes, not only to
stream corridors, but also to the ecosys-
tems of which they are a part. These
changes include degradation of water
quality, decreased water storage and
m activity has profoundly
affected rivers and streams in all
parts of the world, to such an
extent that it is now extremely
difficult to find any stream
which has not been in some way
altered, and probably quite
impossible to find any such river.
H.B.N. Hynes 1970
Fig. 1.2: Concrete-lined channel. Stream systems
across the nation have been altered for a wide
variety of purposes.
conveyance capacity, loss of habitat for
fish and wildlife, and decreased recre-
ational and aesthetic values (National
Research Council 1992). According to
the 1994 National Water Quality Inven-
tory of 617,806 miles of rivers and
streams, only 56 percent fully sup-
ported multiple uses, including drink-
ing water supply, fish and wildlife
habitat, recreation, and agriculture, as
well as flood prevention and erosion
control. Sedimentation and excess nu-
trients were the most significant causes
of degradation (USEPA 1997) in the re-
maining 44 percent.
Given these statistics, the potential for
restoring the conditions in our na-
tion's rivers and streams and protect-
ing them from further damage is
almost boundless.
What Is Meant by Restoration?
Restoration is a complex endeavor that
begins by recognizing natural or
human-induced disturbances that are
damaging the structure and functions of
the ecosystem or preventing its recovery
to a sustainable condition (Pacific
Rivers Council 1996). It requires an un-
derstanding of the structure and func-
tions of stream corridor ecosystems and
1-2
Introduction
-------
jstoration, Rehabilitation, and Reclamation
Restoration is reestablishment of the structure and function of ecosystems (National Research
Council, 1992). Ecological restoration is the process of returning an ecosystem as closely as possible
to predisturbance conditions and functions. Implicit in this definition is that ecosystems are naturally
dynamic. It is therefore not possible to recreate a system exactly. The restoration process reestablishes
the general structure, function, and dynamic but self-sustaining behavior of the ecosystem.
Rehabilitation is making the land useful again after a disturbance. It involves the recovery of eco-
system functions and processes in a degraded habitat (Dunster and Dunster 1996). Rehabilitation
does not necessarily reestablish the predisturbance condition, but does involve establishing geological
and hydrologically stable landscapes that support the natural ecosystem mosaic.
Reclamation is a series of activities intended to change the biophysical capacity of an ecosystem.
The resulting ecosystem is different from the ecosystem existing prior to recovery (Dunster and Dunster
1996). The term has implied the process of adapting wild or natural resources to serve a utilitarian
human purpose such as the conversion of riparian or wetland ecosystems to agricultural, industrial, or
urban uses.
Restoration differs from rehabilitation and reclamation in that restoration is a holistic process not
achieved through the isolated manipulation of individual elements. While restoration aims to return
an ecosystem to a former natural condition, rehabilitation and reclamation imply putting a landscape
to a new or altered use to serve a particular human purpose (National Research Council 1992).
the physical, chemical, and biological
processes that shape them (Dunster and
Dunster 1996).
Restoration, as defined in this docu-
ment, includes a broad range of actions
and measures designed to enable
stream corridors to recover dynamic
equilibrium and function at a self-
sustaining level. The first and most
critical step in implementing restora-
tion is to, where possible, halt distur-
bance activities causing degradation or
preventing recovery of the ecosystem
(Kauffman et al. 1993). Restoration ac-
tions may range from passive ap-
proaches that involve removal or
attenuation of chronic disturbance ac-
tivities to active restoration that in-
volves intervention and installation of
measures to repair damages to the
structure of stream corridors.
Restoration practitioners involved with
stream corridors take one of three basic
approaches to restoration:
Nonintervention and undisturbed recov-
ery: where the stream corridor is
recovering rapidly, and active restora-
tion is unnecessary and even detri-
mental.
Partial intervention for assisted recovery:
where a stream corridor is attempting
to recover, but is doing so slowly or
uncertainly. In such a case, action
may facilitate natural processes
already occurring.
Substantial intervention for managed
recovery: where recovery of desired
functions is beyond the repair capaci-
ty of the ecosystem and active
restoration measures are needed.
The specific goals of any particular
restoration should be defined within
the context of the current conditions
and disturbances in the watershed,
What Is Meant by Restoration?
1-3
-------
Streams Have the Capability to
Restore ThemselvesWe must be
able to recognize these situations.
"Each stream," says Christopher Hunter, "is a whole
greater than the sum of its geologic, climatic, hydrologic,
and biologic parts." Those who would save rivers must
first see each river whole, as a separate, vital, and
unique group of elements and energies that constantly
seeks its own dynamic equilibrium (from Nick Lyons,
Foreword to Better Trout Habitat: A Guide to
Stream Restoration and Management; Hunter 1991).
It is this almost living quality of streams, along with the
capability to repair and sustain themselves with the
removal of disturbances, that this document must con-
vey to the reader. This document addresses the need
within agencies for a comprehensive restoration context,
an appreciation of the importance of removing key dis-
turbances to allow streams to restore themselves, and
to better determine those circumstances when active
intervention in the restoration process is the preferred
alternative.
corridor, and stream. In all likelihood,
restoration will not involve returning a
system to its pristine or original condi-
tion. The goal should be to establish
self-sustaining stream functions.
Because this document may be a pri-
mary reference on ecological restoration
for many users, it is appropriate that
more than one definition of restoration
be included. The following definition of
restoration has been adopted by the So-
ciety for Ecological Restoration (SER).
"Ecological restoration is the process of
assisting the recovery and management
of ecological integrity. Ecological in-
tegrity includes a critical range of vari-
ability in biodiversity, ecological
processes, and structures, regional and
historical context, and sustainable cul-
tural practices."
Why Is a Stream Corridor
Restoration Document Needed?
Interest in restoring stream corridor
ecosystems is expanding nationally and
internationally. Research is under way
and guidelines are being developed for
stream corridor restoration in both the
public and private sectors. The number
of case studies, published papers, tech-
nology exchanges, research projects,
and symposia on both the technical
and process aspects of stream corridor
restoration is increasing.
Over the years, many federal agencies
have contributed to this growing body of
knowledge and have issued manuals and
handbooks pertaining in some way to
stream restoration. Much of this older
literature, however, is significantly differ-
ent from this document in terms of phi-
losophy and technique. Narrow in
scope and focusing on only specific as-
pects, regions, objectives, or treatments,
it may be outdated and not reflective of
new restoration techniques and philoso-
phies. The result has been confusion
and concern among both government
agencies and the public on how to evalu-
ate the need for development and imple-
mentation of restoration initiatives.
In response, this document represents
an unprecedented cooperative effort by
the participating federal agencies to
produce a common technical reference
on stream corridor restoration.
Recognizing that no two stream corri-
dors and no two restoration initiatives
are identical, this technical document
broadly addresses the elements of
restoration that apply in the majority of
situations encountered. The document
1-4
Introduction
-------
It is axiomatic that no restora-
tion can ever be perfect; it is
impossible to replicate the bio-
geochemical and climatological
sequence of events over geolog-
ical time that led to the creation
and placement of even one par-
ticle of soil, much less to exactly
reproduce an entire ecosystem.
Therefore, all restorations are
exercises in approximation and
in the reconstruction of natural-
istic rather than natural assem-
blages of plants and animals
with their physical environ-
ments.
Berger 1990
is not a set of guidelines that cover every
possible restoration situation, but it does
provide a framework in which to plan
restoration actions and alternatives.
What Does the Document Cover?
This document takes a more encom-
passing approach to restoration than
most other texts and manuals. It pro-
vides broadly applicable guidance for
common elements of the restoration
process, but also provides alternatives,
and references to alternatives, which
may be appropriate for site-specific
restoration activities. Moreover, the doc-
ument incorporates and reflects the ex-
periences of the collaborating agencies
and provides a common technical refer-
ence that can be used to restore systems
based on experiences and basic scien-
tific knowledge.
As a general goal, this document pro-
motes the use of ecological processes
(physical, chemical, and biological) and
minimally intrusive solutions to restore
self-sustaining stream corridor func-
Fig.-l.3: Stream corridor restoration can be
applied in both (a) urban and (b) rural settings.
No matter the setting, vegetation and soil
characteristics in the corridor differ distinctly
from the surrounding uplands.
What Does the Document Cover?
1-5
-------
The document
is intended
primarily for
interdisciplinary
technical and
managerial
teams and indi-
viduals responsi-
ble for planning,
designing, and
implementing
stream corridor
restoration
initiatives.
tions. It provides information necessary
to develop and select appropriate alter-
natives and solutions, and to make in-
formed management decisions
regarding valuable stream corridors and
their watersheds. In addition, the docu-
ment recognizes the complexity of most
stream restoration work and promotes
an integrated approach to restoration. It
supports close cooperation among all
participants in order to achieve a com-
mon set of objectives.
The guidance contained in this docu-
ment is applicable nationwide in both
urban and rural settings. The material
presented applies to a range of stream
types, including intermittent and peren-
nial streams of all sizes, and rivers too
small to be navigable by barges. It offers
a scientific perspective on restoration
work ranging from simple to complex,
with the level of detail increasing as the
scale moves from the landscape to the
stream reach.
Fig. 1.4: A stream corridor. The document pro-
vides an overview of stream corridor structure
and functions.
Note that there are several things that
this document is not intended to be.
It is not a cookbook containing pre-
scribed "recipes" or step-by-step
instructions on how to restore a
stream corridor.
While this document refers to issues
such as nonpoint source pollution
and best management practices, wet-
lands restoration and delineation,
lake and reservoir restoration, and
water quality monitoring, it is not
meant to focus on these subjects.
It is not a policy-setting document.
No contributing federal agency is
strictly bound by its contents. Rather,
it suggests and promotes a set of
approaches, methods, and techniques
applicable to most stream corridor
restoration initiatives encountered by
agencies and practitioners.
It is not intended to be an exhaustive
research document on the subject of
stream corridor restoration. It does
provide, however, many references
for those desiring a deeper under-
standing of the principles and theo-
ries underlying techniques and issues
discussed in general terms.
Who Is the Intended Audience?
The document is intended primarily for
interdisciplinary technical and manage-
rial teams and individuals responsible
for planning, designing, and imple-
menting stream corridor restoration ini-
tiatives. The document may also be
useful to others who are working in
stream corridors, including contractors,
landowners, volunteers, agency staff,
and other practitioners.
How Is the Document Organized?
The document is organized to provide
an overview of stream corridors, steps in
restoration plan development, and
guidelines for implementing restoration.
1-6
Introduction
-------
The document has been divided into
three principal parts. Part I provides
background on the fundamental con-
cepts of stream corridor structure,
processes, functions, and the effects of
disturbance. Part II focuses on a gen-
eral restoration plan development
process comprised of several fundamen-
tal steps. Part III examines the informa-
tion presented in Parts I and II to
consider how it can be applied in a
restoration initiative.
Because of the size and complexity of
the document, two features are used to
assist the reader to maintain a clear ori-
entation within the document. These
features will allow the reader to more
easily apply the information to specific
aspects of a stream corridor restoration
initiative. These features are:
Chapter dividers that include major
chapter sections and reader preview
and review questions for each chap-
ter. Table I.I presents a summary of
these questions by chapter.
Short chapter summaries included at
the beginning and end of each chap-
ter that explain where the readers have
been, where they are in the document,
and where they are going.
A special emphasis has been placed on
document orientation due to the special
mission that the document has to ful-
fill. The document audience will in-
clude readers from many different
technical backgrounds and with various
levels of training. The orientation fea-
tures have been included to reinforce
the comprehensive and interdiscipli-
nary perspective of stream corridor
restoration.
How Is the Document Intended to
Be Used?
Use of the document mostly depends
on the goals of the reader. To begin
with, a quick overview of the material is
Agencies Contributing to This
Document
United States Department of Agriculture:
- Agricultural Research Service
- Cooperative State Research, Education, and
Extension Service
- Forest Service
- Natural Resources Conservation Service
m United States Department of Commerce:
- National Oceanic and Atmospheric
Administration
- National Marine Fisheries Service
United States Department of Defense:
- Army Corps of Engineers
m United States Department of Housing and Urban
Development
m United States Department of the Interior:
- Bureau of Land Management
- Bureau of Reclamation
- Fish and Wildlife Service
- United States Geological Survey
- National Park Service
m United States Environmental Protection Agency
m Federal Emergency Management Agency
m Tennessee Valley Authority
suggested prior to more thorough read-
ing. A reader seeking only a general un-
derstanding of the principles of stream
restoration may skip over some of the
technical details in the body of the doc-
ument. Use of document sections,
chapters, and headings allows each
reader to readily identify whether fur-
How Is the Document Intended to Be Used?
1-7
-------
ther, more detailed reading on a subject
will serve his or her purposes.
The reader is urged to recognize the in-
terdisciplinary and technical nature of
stream restoration. While some techni-
cal material may, on the surface, appear
irrelevant, it may in fact be highly rele-
vant to a specific part of the process of
restoring a stream corridor.
Stream corridor restoration technologies
and methodologies are evolving rapidly.
Readers are encouraged to add their own
notes on restoration and to make the
document more relevant to local needs
(e.g., a list of suitable native plant
species for streambank revegetation).
This document is being published in a
notebook form to allow insertion of:
Updated material that will be made
available at the Internet sites printed
in the Preface.
Addition of regional or locally rele-
vant materials collected by the reader.
A Note About Units of Measurement
Metric units are commonly used throughout the world,
but most data published in the United States are in
English units. Although adoption of the metric system
is on the increase in the United Statesand for many
federal agencies this conversion is mandated and being
planned forrestorers of stream corridors will continue
to use data that are in either metric or English units.
Appendix B contains a table of metric to English unit
conversion factors, in case a unit conversion is needed.
Feedback
Readers are encouraged to share their restoration experi-
ences and provide feedback. They can do so by access-
ing the Stream Corridor Restoration home page on the
Internet address printed in the Preface. Other sources
of information may a/so be found by exploring the coop-
erating agencies' home pages on the Internet.
1-8
Introduction
-------
Table 1.1
Chapter 1: Overview of Stream Corridors
1.A Physical Structure and Time at Multiple Scales
What are the structural components of a stream corridor?
Why are stream corridors of special significance, and why should they be
the focus of restoration efforts?
What is the relationship between stream corridors and other landscape
units at broader and more local scales?
What scales should be considered for a stream corridor restoration?
1.B A Lateral View Across the Stream Corridor
How is a stream corridor structured from side to side?
How do these elements contribute to stream corridor functions?
What role do these elements play in the life of the stream?
What do we need to know about the lateral elements of a stream corridor
to adequately characterize a stream corridor for restoration?
How are the lateral elements of a stream corridor used to define flow pat-
terns of a stream?
1.C A Longitudinal View Along the Stream Corridor
What are the longitudinal structural elements of a stream corridor?
How are these elements used to characterize a stream corridor?
What are some of the basic ecological concepts that can be applied to
streams to understand their function and characteristics on a longitudinal
scale?
What do we need to know about the longitudinal elements that are
important to stream corridor restoration?
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
2.A Hydrologic and Hydraulic Processes
Where does stream flow come from?
What processes affect or are involved with stream flow?
How fast, how much, how deep, how often, and when does water flow?
How is hydrology different in urban stream corridors?
2.B Geomorphic Processes
What factors affect the channel cross section and channel profile?
How are water and sediment related?
Where does sediment come from and how is it transported downstream?
What is an equilibrium channel?
What should a channel look like in cross section and in profile?
How do channel adjustments occur?
What is a floodplain?
Is there an important relationship between a stream and its floodplain?
2.C Physical and Chemical Characteristics
What are the major chemical constituents of water?
What are some important relationships between physical habitat and key
chemical parameters?
How are the chemical and physical parameters critical to the aquatic life in
a stream corridor?
What are the natural chemical processes in a stream corridor and water
column ?
How do disturbances in the stream corridor affect the chemical character-
istics of stream water?
How Is the Document Intended to Be Used? I-9
-------
Table 1.1 (continued)
2.D Biological Community Characteristics
What are the important biological components of a stream corridor?
What biological activities and organisms can be found within a stream
corridor?
How does the structure of stream corridors support various populations of
organisms?
What are the structural features of aquatic systems that contribute to the
biological diversity of stream corridors?
What are some important biological processes that occur within a stream
corridor?
What role do fish have in stream corridor restoration?
2.E Functions and Dynamic Equilibrium
What are the major ecological functions of stream corridors?
How are these ecological functions maintained over time?
Is a stream corridor stable?
Are these functions related?
How does a stream corridor respond to all the natural forces act-
ing on it (i.e., dynamic equilibrium)?
Chapter 3: Disturbance Affecting Stream Corridors
3.A Natural Disturbances
How does natural disturbance contribute to shaping a local ecology?
Are natural disturbances bad?
How do you describe or define the frequency and magnitude of natural
disturbance?
How does an ecosystem respond to natural disturbances?
What are some types of natural disturbances you should anticipate in a
stream corridor restoration?
3.B Human-Induced Disturbances
What are some examples of human-induced disturbances at several land-
scape scales?
What are the effects of some common human-induced disturbances such
as dams, channelization, and the introduction of exotic species?
What are some of the effects of land use activities such as agriculture,
forestry, mining, grazing, recreation, and urbanization?
Chapter 4: Getting Organized and Identifying Problems and
Opportunities
4.A Getting Organized
Why is planning important?
Is an Advisory Group needed?
How is an Advisory Group formed?
Who should be on an Advisory Group?
How can funding be identified and acquired?
How are technical teams established and what are their roles?
What procedures should an Advisory Group follow?
How is communication facilitated among affected stakeholders?
1-10 Introduction
-------
Table 1.1 (continued)
4.B Problem and Opportunity Identification
Why is it important to spend resources on the problem ("When everyone
already knows what the problem is")?
How can the anthropogenic changes that caused the need for the restora-
tion initiative be altered or removed?
How are data collection and analysis procedures organized?
How are problems affecting the stream corridor identified?
How are reference conditions for the stream corridor determined?
Why are reference conditions needed?
How are existing management activities influencing the stream corridor?
How are problems affecting the stream corridor described?
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
5.A Developing Restoration Goals and Objectives
How are restoration goals and objectives defined?
How do you describe desired future conditions for the stream corridor and
surrounding natural systems?
What is the appropriate spatial scale for the stream corridor restoration?
What institutional or legal issues are likely to be encountered during a
restoration?
What are the means to alter or remove the anthropogenic changes that
caused the need for the restoration (i.e., passive restoration)?
5.B Alternative Selection and Design
How does a restoration effort target solutions to treat causes of impair-
ment and not just symptoms?
What are important factors to consider when selecting among various
restoration alternatives?
What role does spatial scale, economics, and risk play in helping to select
the best restoration alternative?
Who makes the decisions?
When is active restoration needed?
When are passive restoration methods appropriate?
Chapter 6: Implement, Monitor, Evaluate, and Adapt
6.A Restoration Implementation
What are the steps that should be followed for successful implementation ?
How are boundaries for the restoration defined?
How is adequate funding secured for the duration of the project?
What tools are useful for facilitating implementation?
Why and how are changes made in the restoration plan once implementa-
tion has begun?
How are implementation activities organized?
How are roles and responsibilities distributed among restoration
participants?
How is a schedule developed for installation of the restoration measures?
What permits and regulations will be necessary before moving forward
with restoration measures?
How Is the Document Intended to Be Used? 1-11
-------
Table 1.1 (continued)
6.B Restoration Monitoring, Evaluation, and Adaptive Management
What is the role of monitoring in stream corridor restoration?
When should monitoring begin?
How is a monitoring plan tailored to the specific objectives of a restora-
tion initiative?
Why and how is the success or failure of a restoration effort evaluated?
What are some important considerations in developing a monitoring plan
to evaluate the restoration effort?
Chapter 7: Analysis of Corridor Condition
7.A Hydrologic Processes
How does the stream flow and why is this understanding important?
Is streamflow perennial, ephemeral, or intermittent?
What is the discharge, frequency, and duration of extreme high and low
flows?
How often does the stream flood?
How does roughness affect flow levels?
What is the discharge most effective in maintaining the stream channel
under equilibrium conditions?
How does one determine if equilibrium conditions exist?
What field measurements are necessary?
7.B Geomorphic Processes
How do I inventory geomorphic information on streams and use it to
understand and develop physically appropriate restoration plans?
How do I interpret the dominant channel adjustment processes active at
the site?
How deep and wide should a stream be?
Is the stream stable?
Are basin-wide adjustments occurring, or is this a local problem?
Are channel banks stable, at-risk, or unstable?
What measurements are necessary?
7.C Chemical Characteristics
How do you measure the condition of the physical and chemical condi-
tions within a stream corridor?
Why is quality assurance an important component of stream corridor
analysis activities?
What are some of the water quality models that can be used to evaluate
water chemistry data?
7.D Biological Characteristics
What are some important considerations in using biological indicators for
analyzing stream corridor conditions?
Which indicators have been used successfully?
What role do habitat surveys play in analyzing the biological condition of
the stream corridor?
How do you measure biological diversity in a stream corridor?
What is the role of stream classification systems in analyzing stream corri-
dor conditions?
How can models be used to evaluate the biological condition of a stream
corridor?
What are the characteristics of models that have been used to evaluate
stream corridor conditions?
1-12 Introduction
-------
Table 1.1 (continued)
Chapter 8: Restoration Design
8.A Valley Form, Connectivity, and Dimension
How do you incorporate all the spatial dimensions of the landscape into
stream corridor restoration design?
What criteria can be applied to facilitate good design decisions for stream
corridor restoration?
8.B Soil Properties
How do soil properties impact the design of restoration activities?
What are the major functions of soils in the stream corridor?
How are important soil characteristics, such as soil microfauna and soil
salinity, accounted for in the design process?
8.C Plant Communities
What is the role of vegetative communities in stream corridor restoration?
What functions do vegetative communities fulfill in a stream corridor?
What are some considerations in designing plant community restoration
to ensure that all landscape functions are addressed?
What is soil bioengineering and what is its role in stream corridor restora-
tion?
8.D Habitat Measures
What are some specific tools and techniques that can be used to ensure
recovery of riparian and terrestrial habitat recovery?
8.E Stream Channel Restoration
When is stream channel reconstruction an appropriate restoration option?
How do you delineate the stream reach to be reconstructed?
How is a stream channel designed and reconstructed?
What are important factors to consider in the design of channel recon-
struction (e.g., alignment and average slope, channel dimensions)?
Are there computer models that can assist with the design of channel
reconstruction ?
8.F Streambank Restoration
When should streambank stabilization be included in a restoration?
How do you determine the performance criteria for streambank treat-
ment, including the methods and materials to be used?
What are some streambank stabilization techniques that can be consid-
ered for use ?
8.G Instream Habitat Recovery
What are the principal factors controlling the quality of instream habitat?
How do you determine if an instream habitat structure is needed, and
what type of structure is most appropriate?
What procedures can be used to restore instream habitat?
What are some examples of instream habitat structures?
What are some important questions to address before designing, select-
ing, or installing an instream habitat structure?
How Is the Document Intended to Be Used? 1-13
-------
8.H Land Use Scenarios
What role does land use play in stream corridor degradation and
restoration?
What design approaches can be used to address the impacts of various
land uses (e.g., dams, agriculture, forestry, grazing, mining, recreation,
urbanization)?
What are some disturbances that are often associated with specific land
uses?
What restoration measures can be used to mitigate the impacts of various
land uses?
What are the potential effects of the restoration measures?
Chapter 9: Restoration Implementation, Monitoring, and Management
9.A Restoration Implementation
What are passive forms of restoration and how are they "implemented"?
What happens after the decision is made to proceed with an active rather
than a passive restoration approach?
What type of activities are involved when installing restoration measures?
How can impact on the stream channel and corridor be minimized when
installing restoration measures (e.g., water quality, air quality, cultural
resources, noise)?
What types of equipment are needed for installing restoration measures?
What are some important considerations regarding construction activities
in the stream corridor?
How do you inspect and evaluate the quality and impact of construction
activities in the stream corridor?
What types of maintenance measures are necessary to ensure the ongoing
success of a restoration?
9.B Monitoring Techniques Appropriate for Evaluating Restoration
What methods are available for monitoring biological attributes of
streams?
What can assessment of biological attributes tell you about the status of
the stream restoration?
What physical parameters should be included in a monitoring manage-
ment plan?
How are the physical aspects of the stream corridor evaluated?
How is a restoration monitoring plan developed, and what issues should
be addressed in the plan?
What are the sampling plan design issues that must be addressed to ade-
quately detect trends in stream corridor conditions?
How do you ensure that the monitoring information is properly collected,
analyzed, and assessed (i.e., quality assurance plans)?
9.C Restoration Management
What are important management priorities with ongoing activities and
resource uses within the stream corridor?
What are some management decisions that can be made to support
stream restoration?
What are some example impacts and management options with various
types of resource use within the stream corridor (e.g., forest management,
grazing, mining, fish and wildlife, urbanization)?
When is restoration complete?
1-14 Introduction
-------
Parti
riffle
pool
earn channel
at baseflow
-------
-------
Background
Chapter 1: Overview of Stream Corridors
Chapter 2: Stream Corridor Processes,
Characteristics, and Functions
Chapter 3: Disturbance Affecting Stream
Corridors
The purpose of Part I is to provide
background on fundamental concepts
necessary for planning and designing
stream corridor restoration. Ward (1989)
described relationships that occur in the
stream corridor using a four-dimensional
framework (see figure below). This frame-
work serves as a good starting point for
examining stream corridors.
Untrained observers typically focus on
only the longitudinal dimension of the
frameworkthe stream as it flows from
headwaters to mouth. This perspective is
limited, however, because lateral and verti-
cal movements of water, materials, energy,
and organisms also influence the character
of the stream corridor.
The time dimension is also critically impor-
tant because stream corridors are
constantly changing. Changes can
be detected in any number of
time framesfrom minutes to
millennia. A challenge for
restoration practitioners,
UHBHIiaJHM
Dimensior
dimensions of the stream corridor.
A four-dimensional framework
serves as a good starting point for
examining stream corridors.
-------
therefore, is to view time as well as
space in the stream corridor.
The physical structure of the stream
corridor is formed by the move-
ment of water, materials, energy,
and organisms within this multi-
dimensional framework. As move-
ment affects structure, so too does
structure affect movement. This
natural feedback loop helps to
create a state of balance within
the stream corridor known as dy-
namic equilibrium, which allows
the corridor to accommodate lim-
ited change while maintaining its
essential structure and functions.
Disturbances that affect stream
corridors can be natural or human-
induced. If they are severe enough,
they can alter the structure and func-
tions of a stream corridor to a point
that dynamic equilibrium is disrup-
ted. Restoration can then be em-
The care of the rivers is not a question of the
rivers but of the human heart.
Tanaka Shozo
ployed to try to reestablish structure
and functions so natural dynamic
equilibrium can once again occur.
Part I is composed of three chapters:
m Chapter 1 defines the compo-
nents of the stream corridor and
introduces the concepts of scale
and structure. With these concepts
in mind, structural elements with-
in the stream corridor are exam-
ined first in the lateral and then
in the longitudinal dimensions.
m Chapter 2 presents information
on the hydrologic and geomor-
phic processes that help build
structure in the stream corridor.
Also addressed are the chemical
and biological characteristics that
make a stream corridor unique in
the landscape. The chapter con-
cludes with a discussion of the six
critical functions of the stream
corridor ecosystem and intro-
duces the concept of dynamic
equilibrium.
m Chapter 3 summarizes the range
of disturbances that can stress the
stream corridor ecosystem, impact
dynamic equilibrium, and impair
the corridor's ability to perform
critical functions. Both natural and
human-induced disturbances are
discussed with a special emphasis
on land use activities.
The background information pre-
sented in Part I will be applied both
in restoration planning (Part II) and
plan implementation (Part III).
Hi
Part I: Background
-------
Overview of
Stream
Corridors
1.A Physical Structure and Time at
Multiple Scales
1.B A Lateral View Across the Stream
Corridor
1.C A Longitudinal View Along the
Stream Corridor
A stream corridor is an ecosystem that
usually consists of three major ele-
ments:
m Stream channel
m Floodplain
m Transitional upland fringe
Together they function as dynamic and
valued crossroads in the landscape.
(Figure 1.1) Water and other materials,
energy, and organisms meet and interact
within the stream corridor over space and
time. This movement provides critical func-
tions essential for maintaining life such as
cycling nutrients, filtering contaminants
from runoff, absorbing and gradually re-
leasing floodwaters, maintaining fish and
wildlife habitats, recharging ground water,
and maintaining stream flows.
The purpose of this chapter is to define
the components of the
stream corridor and intro-
duce the concepts of scale
and structure. The chapter is
divided into three subsections,
Figure 1.1: Stream corridors func-
tion as dynamic crossroads in the
landscape. Water and other materi-
als, energy, and organisms meet and
interact within the corridor.
-------
Section 1.A: Physical Structure and stream corridors. The focus here is
Time at Multiple Scales on tne /atera/ dimension of struc-
An important initial task is to iden- ture, which affects the movement
tify the spatial and time scales most of water, materials, energy, and or-
appropriate for planning and de- ganisms from upland areas into the
signing restoration. This subsection stream channel.
introduces elements of structure
Lon9«udi"al view
used in landscape ecology and re-
, ^J . Along the Stream Corridor
lates them to a hierarchy of spacial
scales ranging from broad to local. This section takes a longitudinal
The importance of integrating time view of ^ucture, specifically as a
scales into the restoration process is stream travels down the valley from
also discussed headwaters to mouth. It includes
discussions of channel form, sedi-
Section 1.B: A Lateral View Across ment transport and deposition, and
the Stream Corridor frow biological communities have
The purpose of this and the follow- adapted to different stages of the
ing subsection is to introduce the river continuum.
types of structure found within
1-2 Chapter 1: Overview of Stream Corridors
-------
1.A Physical Structure and Time at Multiple
A hierarchy of five spatial scales, which
range from broad to local, is displayed
in Figure 1.2. Each element within the
scales can be viewed as an ecosystem
with links to other ecosystems. These
linkages are what make an ecosystem's
external environment as important to
proper functioning as its internal envi-
ronment (Odum 1989).
Landscapes and stream corridors are
ecosystems that occur at different spa-
tial scales. Examining them as ecosys-
tems is useful in explaining the basics
of how landscapes, watersheds, stream
corridors, and streams function. Many
common ecosystem functions involve
movement of materials (e.g., sediment
and storm water runoff), energy (e.g.,
heating and cooling of stream waters),
and organisms (e.g., movement of
mammals, fish schooling, and insect
swarming) between the internal and ex-
ternal environments (Figure 1.3).
The internal/external movement model
becomes more complex when one con-
siders that the external environment of
a given ecosystem is a larger ecosystem.
A stream ecosystem, for example, has an
input/output relationship with the next
higher scale, the stream corridor. This
scale, in turn, interacts with the land-
scape scale, and so on up the hierarchy.
Similarly, because each larger-scale
ecosystem contains the one beneath it,
the structure and functions of the
smaller ecosystem are at least part of the
structure and functions of the larger.
Furthermore, what is not part of the
smaller ecosystem might be related to
it through input or output relationships
with neighboring ecosystems. Investigat-
ing relationships between structure and
scale is a key first step for planning and
designing stream corridor restoration.
Physical Structure
Landscape ecologists use four basic
terms to define spatial structure at a
particular scale (Figure 1.4):
Matrix, the land cover that is domi-
nant and interconnected over the
majority of the land surface. Often
the matrix is forest or agriculture,
but theoretically it can be any land
cover type.
Patch, a nonlinear area (polygon)
that is less abundant than, and differ-
ent from, the matrix.
Corridor, a special type of patch that
links other patches in the matrix.
Typically, a corridor is linear or elon-
gated in shape, such as a stream
corridor.
Mosaic, a collection of patches, none
of which are dominant enough to be
interconnected throughout the land-
scape.
These simple structural element con-
cepts are repeated at different spatial
scales. The size of the area and the spa-
tial resolution of one's observations de-
termine what structural elements one is
observing. For example, at the landscape
scale one might see a matrix of mature
forest with patches of cropland, pasture,
clear-cuts, lakes, and wetlands. Looking
more closely at a smaller area, one
might consider an open woodland to be
a series of tree crowns (the patches)
against a matrix of grassy ground cover.
On a reach scale, a trout might perceive
pools and well-sheltered, cool, pockets
of water as preferred patches in a matrix
of less desirable shallows and riffles, and
the corridor along an undercut stream-
bank might be its only way to travel
safely among these habitat patches.
FAST
FORWARD
Preview Chap-
ter 2, Section E
for a discussion
of the six criti-
cal functions
performed by
stream corridor
ecosystems.
Landscapes,
watersheds,
stream corri-
dors, and
streams are
ecosystems
that occur at
different spa-
tial scales.
Physical Structure and Time at Multiple Scales
1-3
-------
Region Scale
Chesapeake Bay
Watershed
Landscape Scale
Patuxent River Watershed
mixed landscape
suburban
agricultural
forest cover
Washington, DC
Stream Corridor Scale
Patuxent Stream
Corridor
Patuxent Reservoir
Watershed
Figure 1.2: Ecosystems at multiple scales.
Stream corridor restoration can occur at
any scale, from regional to reach.
1-4
Chapter 1: Overview of Stream Corridors
-------
output environment
At the other extreme, the coarsest of the
imaging satellites that monitor the earth's
surface might detect only patches or cor-
ridors of tens of square miles in area,
and matrices that seem to dominate a
whole region. At all levels, the matrix-
patch-corridor-mosaic model provides a
useful common denominator for de-
scribing structure in the environment.
Figure 1.5 displays examples of the ma-
trices, patches, and corridors at broad
and local scales. Practitioners should
always consider multiple scales when
planning and designing restoration.
Structure at Scales Broader Than
the Stream Corridor Scale
The landscape scale encompasses the
stream corridor scale. In turn, the land-
scape scale is encompassed by the larger
regional scale. Each scale within the hier-
archy has its own characteristic structure.
The "watershed scale" is another form of
spatial scale that can also encompass the
stream corridor. Although watersheds
occur at all scales, the term "watershed
scale" is commonly used by many practi-
tioners because many functions of the
stream corridor are closely tied to drain-
age patterns. For this reason, the "water-
shed scale" is included in this discussion.
patch
Figure 1.3: A simple
ecosystem model.
Materials, energy, and
organisms move from
an external input
environment, through
the ecosystem, and
into an external out-
put environment.
Landscape
Geologists use
four basic
terms to define
spatial struc-
ture at a par-
ticular scale-
matrix, patch,
corridor, and
mosaic.
Figure 1.4: Spatial
structure. Landscapes
can be described in
terms of matrix,
patch, corridor, and
mosaic at various
scales.
Physical Structure and Time at Multiple Scales
1-5
-------
Practitioners
should always
consider multi-
ple scales
when planning
and designing
restoration.
(a) (b)
Figure 1.5: Spatial structure at (a) broad and (b) local scales. Patches, corridors, and matrices are
visible at the broad regional scale and the local reach scale.
Regional Scale
A region is a broad geographical area
with a common macroclimate and
sphere of human activities and interests
(Forman 1995). The spatial elements
found at the regional scale are called
landscapes. Figure 1.6 includes an ex-
ample of the New England region with
landscapes defined both by natural
cover and by land use.
Matrices in the United States include:
Deserts and arid grasslands of the
arid Southwest.
Forests of the Appalachian
Mountains.
Agricultural zones of the Midwest.
At the regional scale, patches generally
include:
Major lakes (e.g., the Great Lakes).
Major wetlands (e.g., the Everglades).
Major forested areas (e.g., redwood
forests in the Pacific Northwest).
Major metropolitan zones (e.g., the
Baltimore-Washington, DC, metro-
politan area).
Major land use areas such as agricul-
ture (e.g., the Corn Belt).
Corridors might include:
Mountain ranges.
Major river valleys.
Interregional development along a
major transportation corridor.
Most practitioners of stream corridor
restoration do not usually plan and de-
sign restoration at the regional scale.
The perspective is simply too broad for
most projects. Regional scale is intro-
duced here because it encompasses the
scale very pertinent to stream corridor
restorationthe landscape scale.
1-6
Chapter 1: Overview of Stream Corridors
-------
Landscape Scale
A landscape is a geographic area distin-
guished by a repeated pattern of com-
ponents, which include both natural
communities like forest patches and
wetlands and human-altered areas like
croplands and villages. Landscapes can
vary in size from a few to several thou-
sand square miles.
At the landscape scale, patches (e.g.,
wetlands and lakes) and corridors
(e.g., stream corridors) are usually
described as ecosystems. The matrix is
usually identified in terms of the pre-
dominant natural vegetation commu-
nity (e.g., prairie-type, forest-type, and
wetland-type) or land-use-dominated
Figure 1.6: The New England region. Structure
in a region is typically a function of natural
cover and land use.
Source: Forman (1995). Reprinted with the permis-
sion of Cambridge University Press.
ecosystem (e.g., agriculture and urban)
(Figure 1.7).
Landscapes differ from one another
based on the consistent pattern formed
by their structural elements, and the
predominant land cover that comprises
their patches, corridors, and matrices.
Examples of landscapes in the United
States include:
A highly fragmented east coast mosa-
ic of suburban, forest, and agricultur-
al patches.
A north-central agricultural matrix
with pothole wetlands and forest
patches.
A Sonoran desert matrix with willow-
cottonwood corridors.
A densely forested Pacific Northwest
matrix with a pattern of clear-cut
patches.
Southern Quebec
Region
Adirondack
Region
The Maritimes
Region
\
New
England
Region
New
York
Region
spruce-fir
northern hardwood
agricultural
oak forest
pitch pine-oak
urban
suburban
salt marsh
rivers and lakes
barrens
industrial
A landscape is
a geographic
area distin-
guished by a
repeated pat-
tern of compo-
nents, which
include both
natural com-
munities like
forest patches
and wetlands
and human-
altered areas
like croplands
and villages.
Physical Structure and Time at Multiple Scales
1-7
-------
A more com-
plete broad
scale perspec-
tive of the
stream corridor
is achieved
when water-
shed science is
combined with
landscape
ecology.
Figure 1.7: Structure at the landscape scale.
Patches and corridors are visible within an agri-
cultural matrix.
A woodlot within an agricultural ma-
trix and a wetland in an urban matrix
are examples of patches at the land-
scape scale. Corridors at this scale
include ridgelines, highways, and
the topic of this documentstream
corridors.
At the landscape scale it is easy to per-
ceive the stream corridor as an ecosys-
tem with an internal environment and
external environment (its surrounding
landscape). Corridors play an impor-
tant role at the landscape scale and at
other scales. Recall that a key attribute
of ecosystems is the movement of en-
ergy, materials, and organisms in,
through, and out of the system. Corri-
dors typically serve as a primary path-
way for this movement. They connect
patches and function as conduits be-
tween ecosystems and their external
environment. Stream corridors in par-
ticular provide a heightened level of
functions because of the materials and
organisms found in this type of land-
scape linkage.
Spatial structure, especially in corridors,
helps dictate movement in, through,
and out of the ecosystem; conversely,
this movement also serves to change
the structure over time. Spatial struc-
ture, as it appears at any one point in
time, is therefore the end result of
movement that has occurred in the
past. Understanding this feedback loop
between movement and structure is a
key to working with ecosystems in any
scale.
"Watershed Scale"
Much of the movement of material, en-
ergy, and organisms between the stream
corridor and its external environments
is dependent on the movement of
water. Consequently, the watershed
concept is a key factor for planning and
designing stream corridor restoration.
The term "scale," however, is incorrectly
applied to watersheds.
A watershed is defined as an area of land
that drains water, sediment, and dis-
solved materials to a common outlet at
some point along a stream channel
(Dunne and Leopold 1978). Water-
sheds, therefore, occur at multiple
scales. They range from the largest river
basins, such as the watersheds of the
Mississippi, Missouri, and Columbia,
to the watersheds of very small streams
that measure only a few acres in size.
The term "watershed scale" (singular) is
a misnomer because watersheds occur
at a very wide range of scales. This doc-
ument focuses primarily on the water-
sheds of small to medium-scale streams
and rivers. Watersheds in this size range
can contain all or part of a few different
landscapes or can be entirely encom-
passed by a larger landscape.
Ecological structure within watersheds
can still be described in matrix, patch,
corridor, and mosaic terms, but a dis-
cussion of watershed structure is more
meaningful if it also focuses on ele-
1-8
Chapter 1: Overview of Stream Corridors
-------
ments such as upper, middle, and lower
watershed zones; drainage divides;
upper and lower hillslopes; terraces,
floodplains, and deltas; and features
within the channel. These elements and
their related functions are discussed in
sections B and C of this chapter.
In short, watersheds and landscapes
overlap in size range and are defined by
different environmental processes.
Whereas the landscape is defined pri-
marily by terrestrial patterns of land
cover that may continue across drainage
divides to where the consistent pattern
ends, the watershed's boundaries are
based on the drainage divides them-
selves. Moreover, the ecological
processes occurring in watersheds are
more closely linked to the presence and
movement of water; therefore as func-
tioning ecosystems, watersheds also dif-
fer from landscapes.
The difference between landscape scale
and "watershed scale" is precisely why
practitioners should consider both
when planning and designing stream
corridor restoration. For decades the
watershed has served as the geographic
unit of choice because it requires con-
sideration of hydrologic and geomor-
phic processes associated with the
movement of materials, energy, and or-
ganisms into, out of, and through the
stream corridor.
The exclusive use of watersheds for the
broad-scale perspective of stream corri-
dors, however, ignores the materials, en-
ergy, and organisms that move across
and through landscapes independent of
water drainage. Therefore, a more com-
plete broad-scale perspective of the
stream corridor is achieved when water-
shed science is combined with land-
scape ecology.
Hydrologic Unit Cataloging and Reach
File/National Hydrography Dataset
The USGS developed a national framework for cata-
loging watersheds of different geographical scales. Each
level, or scale, in the hierarchy is designated using the
hydrologic unit cataloging (HUC) system. At the national
level this system involves an eight-digit code that
uniquely identifies four levels of classification.
The largest unit in the USGS HUC system is the water
resource region. Regions are designated by the first two
digits of the code. The remaining numbers are used to
further define subwatersheds within the region down to
the smallest scale called the cataloging unit. For exam-
ple, 10240006 is the hydrologic unit code for the Little
Nemaha River in Nebraska. The code is broken down as
follows:
1 0 Region
1024 Subregion
102400 Accounting code
10240006 Cataloging unit
There are 21 regions, 222 subregions, 352 accounting
units, and 2,150 cataloging units in the United States.
The USGS's Hydrologic Unit Map Series documents these
hierarchical watershed boundaries for each state. Some
state and federal agencies have taken the restoration ini-
tiative to subdivide the cataloging unit into even smaller
watersheds, extending the HUC code to 11 or 14 digits.
The Reach File/National Hydrography Dataset (RF/NHD) is
a computerized database of streams, rivers, and other
water bodies in the United States. It is cross-referenced
with the HUC system in a geographic information system
(GIS) format so users can easily identify both watersheds
and the streams contained within their boundaries.
Physical Structure and Time at Multiple Scales
1-9
-------
Structure at the Stream Corridor
Scale
The stream corridor is a spatial element
(a corridor) at the watershed and land-
scape scales. But as a part of the hierar-
chy, it has its own set of structural
elements (Figure 1.8). Riparian
(streamside) forest or shrub cover is a
common matrix in stream corridors. In
other areas, herbaceous vegetation
might dominate a stream corridor.
Examples of patches at the stream corri-
dor scale include both natural and
human features such as:
Wetlands.
Forest, shrubland, or grassland
patches.
Oxbow lakes.
Residential or commercial develop-
ment.
Islands in the channel.
Passive recreation areas such as pic-
nic grounds.
Corridors at the stream corridor scale
include two important elementsthe
stream channel and the plant commu-
nity on either side of the stream. Other
examples of corridors at this scale
might include:
Streambanks
Floodplains
Feeder (tributary) streams
Trails and roads
Structure Within the Stream
Corridor Scale
At the stream scale, patches, corridors,
and the background matrix are defined
within and near the channel and in-
clude elements of the stream itself and
its low floodplains (Figure 1.9). At the
next lower scale, the stream itself is seg-
mented into reaches.
Reaches can be distinguished in a num-
ber of ways. Sometimes they are defined
by characteristics associated with flow.
High-velocity flow with rapids is obvi-
ously separable from areas with slower
flow and deep, quiet pools. In other in-
stances practitioners find it useful to de-
fine reaches based on chemical or
biological factors, tributary confluences,
or by some human influence that
makes one part of a stream different
from the next.
Examples of patches at the stream and
reach scales might include:
Riffles and pools
Woody debris
Aquatic plant beds
Islands and point bars
Examples of corridors might include:
Protected areas beneath overhanging
banks.
Figure 1.8: Structural elements at a stream
corridor scale. Patches, corridors, and matrix
are visible within the stream corridor.
1-10
Chapter 1: Overview of Stream Corridors
-------
The thalweg, the "channel within the
channel" that carries water during
low-flow conditions.
Lengths of stream defined by physi-
cal, chemical, and biological similari-
ties or differences.
Lengths of stream defined by human-
imposed boundaries such as political
borders or breaks in land use or
ownership.
Temporal Scale
The final scale concept critical for the
planning and design of stream corridor
restoration is time.
In a sense, temporal hierarchy parallels
spatial hierarchy. Just as global or re-
gional spatial scales are usually too
large to be relevant for most restoration
initiatives, planning and designing
restoration for broad scales of time is
not usually practical. Geomorphic or
climatic changes, for example, usually
occur over centuries to millions of
years. The goals of restoration efforts,
by comparison, are usually described in
time frames of years to decades.
Land use change in the watershed, for
example, is one of many factors that
can cause disturbances in the stream
corridor. It occurs on many time scales,
however, from a single year (e.g., crop
rotation), to decades (e.g., urbaniza-
tion), to centuries (e.g., long-term forest
management). Thus, it is critical for the
practitioner to consider a relevant range
of time scales when involving land use
issues in restoration planning and de-
sign.
Flooding is another natural process that
varies both in space and through time.
Spring runoff is cyclical and therefore
fairly predictable. Large, hurricane-in-
duced floods that inundate lands far be-
yond the channel are neither cyclical
nor predictable, but still should be
Figure 1.9: Structural elements at a stream
scale. Patches, corridors, and matrix are visible
within the stream.
planned for in restoration designs.
Flood specialists rank the extent of
floods in temporal terms such as 10-
year, 100-year, and 500-year events
(10%, 1%, 0.2% chance of recurrence.
See Chapter 7 Flow Frequency Analysis
for more details.). These can serve as
guidance for planning and designing
restoration when flooding is an issue.
Practitioners of stream corridor restora-
tion may need to simultaneously plan
in multiple time scales. If an instream
structure is planned, for example, care
might be taken that (1) installation
does not occur during a critical spawn-
ing period (a short-term consideration)
and (2) the structure can withstand a
100-year flood (a long-term considera-
tion). The practitioner should never try
to freeze conditions as they are, at the
completion of the restoration. Stream
corridor restoration that works with the
dynamic behavior of the stream ecosys-
tem will more likely survive the test of
time.
Stream corri-
dor restoration
that works
with the dy-
namic behavior
of the stream
ecosystem will
more likely
survive the
test of time.
Physical Structure and Time at Multiple Scales
1-11
-------
1.B A Lateral View Across the Stream Corridor
The previous section described how the
matrix-patch-corridor-mosaic model
can be applied at multiple scales to ex-
amine the relationships between the
stream corridor and its external envi-
ronments. This section takes a closer
look at physical structure in the stream
corridor itself. In particular, this section
focuses on the lateral dimension. In
cross section, most stream corridors
have three major components
(Figure 1.10):
STREAM
CHANNEL
TRANSITIONAL
UPLAND FRINGE
FLOODPLAIN
Figure 1.10: The three major components of a
stream corridor in different settings (a) and
(b). Even though specific features might differ
by region, most stream corridors have a chan-
nel, floodplain, and transitional upland fringe.
m Stream channel, a channel with flow-
ing water at least part of the year.
Floodplain, a highly variable area on
one or both sides of the stream chan-
nel that is inundated by floodwaters
at some interval, from frequent to
rare.
Transitional upland fringe, a portion of
the upland on one or both sides of
the floodplain that serves as a transi-
tional zone or edge between the
floodplain and the surrounding land-
scape.
Some common features found in the
river corridor are displayed in Figure
1.11. In this example the floodplain is
seasonally inundated and includes fea-
tures such as floodplain forest, emer-
gent marshes and wet meadows. The
transitional upland fringe includes an
upland forest and a hill prairie. Land-
forms such as natural levees, are created
by processes of erosion and sedimenta-
tion, primarily during floods. The vari-
ous plant communities possess unique
moisture tolerances and requirements
and consequently occupy distinct land-
forms.
Each of the three main lateral compo-
nents is described in the following
subsections.
Stream Channel
Channels are formed, maintained, and
altered by the water and sediment they
carry. Usually they are gently rounded
in shape and roughly parabolic, but
form can vary greatly.
Figure 1.12 presents a cross section of a
typical stream channel. The sloped
bank is called a scarp. The deepest part
of the channel is called the thalweg. The
dimensions of a channel cross section
define the amount of water that can
1-12
Chapter 1: Overview of Stream Corridors
-------
1/1
5L
o"
g
o
o
rt>
g
rf
fD
Q_
rD
fD
T3
QJ
~j
»
|
ro
QJ
Q.
O
g
A
r
m.
c
T3
3
Q.
corridor
high
river
stage
low river
stage
bluff
floodplain
lake
natural
| levee | slough
island
floodplain
main
channel
backwater lake
floodplain
bluff
Figure 1.11: A cross section of a river corridor. The three main components of the river corridor
can be subdivided by structural features and plant communities. (Vertical scale and channel width
are greatly exaggerated.)
Source: Sparks, Bioscience, vol. 45, p. 170, March 1995. ©1995 American Institute of Biological Science.
pass through without spilling over the
banks. Two attributes of the channel are
of particular interest to practitioners,
channel size and streamflow.
Channel Size
Channel size is determined by four
basic factors:
Sediment discharge (QJ
Sediment particle size (D50)
Streamflow (QJ
Stream slope (S)
Lane (1955) showed this relationship
qualitatively as:
Qs D50 - Qw S
This equation can be envisioned as a
balance with sediment load on one
weighing pan and streamflow on the
other (Figure 1.13). The hook holding
the sediment pan can slide along the
horizontal arm according to sediment
size. The hook holding the streamflow
side slides according to stream slope.
Channel equilibrium occurs when all
four variables are in balance. If one
variable changes, one or more of the
other variables must increase or de-
crease proportionally if equilibrium is
to be maintained. For example, if slope
is decreased and streamflow remains
the same, either the sediment load or
the size of the particles must also de-
crease. Likewise, if flow is increased and
the slope stays the same, sediment load
or sediment particle size has to increase
to maintain channel equilibrium.
If a change occurs, the balance will tem-
porarily be tipped and equilibrium lost.
The stream will then change its level ei-
ther upward (aggradation) or down-
ward (degradation or incising),
thalweg
Figure 1.12: Cross section of a stream channel.
The scarp is the sloped bank and the thalweg is
the lowest part of the channel.
A Lateral View Across the Stream Corridor
1-13
-------
Figure 1.13: Factors affecting channel degradation and aggradation. The "size" of the channel is
determined by the stream's energy, the slope, and the flow of water in balance with the size and
quantity of the sediment particles the stream moves.
Source: Rosgen (1996), from Lane, Proceedings, 1955. Published with the permission of American Society of
Civil Engineers.
FAST
FORWARD i
Preview Chap-
ter 2, Section B
for more dis-
cussion on the
stream balance
equation. Pre-
view Chapter 7,
Section B for
information on
measuring and
analyzing these
variables and
the use of sedi-
ment transport
equations.
depending on which direction the bal-
ance is tipped.
The stream balance equation is useful
for making qualitative predictions con-
cerning channel impacts due to changes
in runoff or sediment loads from the
watershed. Quantitative predictions,
however, require the use of more com-
plex equations.
Sediment transport equations, for ex-
ample, are used to compare sediment
load and energy in the stream. If excess
energy is left over after the load is
moved, channel adjustment occurs as
the stream picks up more load by erod-
ing its banks or scouring its bed. No
matter how much complexity is built
into these and other equations of this
type, however, they all relate back to the
basic balance relationships described by
Lane.
Streamflow
A distinguishing feature of the channel
is streamflow. As part of the water cycle,
the ultimate source of all flow is precip-
itation. The pathways precipitation
takes after it falls to earth, however, af-
fect many aspects of streamflow includ-
ing its quantity, quality, and timing.
Practitioners usually find it useful to di-
vide flow into components based on
these pathways.
The two basic components are:
Storm/low, precipitation that reaches
the channel over a short time frame
through overland or underground
routes.
Base/low, precipitation that percolates
to the ground water and moves slow-
ly through substrate before reaching
the channel. It sustains streamflow
during periods of little or no precipi-
tation.
1-14
Chapter 1: Overview of Stream Corridors
-------
Streamflow at any one time might con-
sist of water from one or both sources.
If neither source provides water to the
channel, the stream goes dry.
A storm hydrograph is a tool used to
show how the discharge changes with
time (Figure 1.14). The portion of the
hydrograph that lies to the left of the
peak is called the rising limb, which
shows how long it takes the stream to
peak following a precipitation event.
The portion of the curve to the right of
the peak is called the recession limb.
Channel and Ground Water
Relationships
Interactions between ground water and
the channel vary throughout the water-
shed. In general, the connection is
strongest in streams with gravel
riverbeds in well-developed alluvial
floodplains.
lag time
C .£
£ E
ro
C£
recession
limb
time
of rise
2 3
Time (days)
Figure 1.14: A storm hydrograph. A hydro-
graph shows how long a stream takes to rise
from baseflow to maximum discharge and then
return to baseflow conditions.
lag time before
urbanization
lag time after
urbanization
1
C .£
v Q
= E
.E 55
03
o:
Time (hours)
Figure 1.15: A comparison of hydrographs
before and after urbanization. The discharge
curve is higher and steeper for urban streams
than for natural streams.
Change in Hydrology After Urbanization
The hydrology of urban streams changes as sites are cleared
and natural vegetation is replaced by impervious cover such
as rooftops, roadways, parking lots, sidewalks, and driveways.
One of the consequences is that more of a stream's annual
flow is delivered as storm water runoff rather than baseflow.
Depending on the degree of watershed impervious cover, the
annual volume of storm water runoff can increase by up to
16 times that for natural areas (Schueler 1995). In addition,
since impervious cover prevents rainfall from infiltrating into
the soil, less flow is available to recharge ground water.
Therefore, during extended periods without rainfall, baseflow
levels are often reduced in urban streams (Simmons and
Reynolds 1982).
Storm runoff moves more rapidly over smooth, hard pave-
ment than over natural vegetation. As a result, the rising
limbs of storm hydrographs become steeper and higher in
urbanizing areas (Figure 1.15). Recession limbs also decline
more steeply in urban streams.
A Lateral View Across the Stream Corridor
1-15
-------
Figure 1.16 presents two types of water
movement:
Influent or "losing" reaches lose stream
water to the aquifer.
Effluent or "gaining" reaches receive
discharges from the aquifer.
Practitioners categorize streams based
on the balance and timing of the storm-
flow and baseflow components. There
are three main categories:
Ephemeral streams flow only during or
immediately after periods of precipi-
tation. They generally flow less than
30 days per year (Figure 1.17).
Intermittent streams flow only during
certain times of the year. Seasonal
flow in an intermittent stream usual-
ly lasts longer than 30 days per year.
Perennial streams flow continuously
during both wet and dry times.
Baseflow is dependably generated
from the movement of ground water
into the channel.
Discharge Regime
Discharge is the term used to describe
the volume of water moving down the
channel per unit time (Figure 1.18).
The basic unit of measurement used in
the United States to describe discharge
is cubic foot per second (cfs).
Figure 1.17: An ephemeral stream. Ephemeral
streams flow only during or immediately after
periods of precipitation.
Discharge is calculated as:
Q = AV
where:
Q = Discharge (cfs)
A = Area through which the water is
flowing in square feet
V = Average velocity in the downstream
direction in feet per second
As discussed earlier in this section,
streamflow is one of the variables that
determine the size and shape of the
channel. There are three types of char-
acteristic discharges:
Channel-forming (or dominant) dis-
charge. If the streamflow were held
constant at the channel-forming
Y
(a) Influent Stream Reach
(b) Effluent Stream Reach
Figure 1.16: Cross sections of (a) influent and (b) effluent stream reaches. Influent or "losing"
reaches lose stream water to the aquifer. Effluent or "gaining" reaches receive discharges from
the aquifer.
1-16
Chapter 1: Overview of Stream Corridors
-------
discharge, it would result in channel
morphology close to the existing
channel. However, there is no
method for directly calculating
channel-forming discharge.
An estimate of channel-forming dis-
charge for a particular stream reach
can, with some qualifications, be
related to depth, width, and shape of
channel. Although channel-forming
discharges are strictly applicable only
to channels in equilibrium, the con-
cept can be used to select appropriate
channel geometry for restoring a dis-
turbed reach.
Effective discharge. The effective dis-
charge is the calculated measure of
channel-forming discharge.
Computation of effective discharge
requires long-term water and sedi-
ment measurements, either for the
stream in question or for one very
similar. Since this type of data is
often not available for stream restora-
tion sites, modeled or computed data
are sometimes substituted. Effective
Figure 1.18: Channel discharge. Discharge is
the product of area times velocity.
discharge can be computed for either
stable or evolving channels.
Bankfull discharge. This discharge
occurs when water just begins to
leave the channel and spread onto
the floodplain (Figure 1.19).
Bankfull discharge is equivalent to
channel-forming (conceptual) and
effective (calculated) discharge for
alluvial streams in equilibrium.
charge
Channel-Forming Discha
To envision the concept of channel-
forming discharge, imagine placing a
water hose discharging at constant rate
in a freshly tilled garden. Eventually, a
small channel will form and reach an
equilibrium geometry.
At a larger scale, consider a newly
constructed floodwater- retarding
reservoir that slowly releases stored
floodwater at a constant flow rate.
This flow becomes the new channel-
forming discharge and will alter chan-
nel morphology until the channel
reaches equilibrium.
Figure 1.19: Bankfull discharge. This is the flow
at which water begins to leave the channel
and move onto the floodplain.
A Lateral View Across the Stream Corridor
1-17
-------
FAST
FORWARD
Preview Chap-
ter 7, Section B
for a discussion
of calculating
effective dis-
charge. This
computation
should be per-
formed by a
professional
with a good
background in
hydrology, hy-
draulics, and
sediment
transport.
Floodplain
The floor of most stream valleys is rela-
tively flat. This is because over time the
stream moves back and forth across the
valley floor in a process called lateral
migration. In addition, periodic flood-
ing causes sediments to move longitudi-
nally and to be deposited on the valley
floor near the channel. These two
processes continually modify the flood-
plain.
Through time the channel reworks the
entire valley floor. As the channel mi-
grates, it maintains the same average
size and shape if conditions upstream
remain constant and the channel stays
in equilibrium.
Two types of floodplains may be de-
fined (Figure 1.20):
Hydrologic floodplain, the land adja-
cent to the baseflow channel residing
below bankfull elevation. It is inun-
dated about two years out of three.
Not every stream corridor has a
hydrologic floodplain.
Topographic floodplain, the land adja-
cent to the channel including the
hydrologic floodplain and other
lands up to an elevation based on
the elevation reached by a flood peak
of a given frequency (for example,
the 100-year floodplain).
Professionals involved with flooding
issues define the boundaries of a
floodplain in terms of flood frequen-
cies. Thus, 100-year and 500-year
floodplains are commonly used in
the development of planning and
regulation standards.
Flood Storage
The floodplain provides temporary stor-
age space for floodwaters and sediment
produced by the watershed. This at-
tribute serves to add to the lag time of a
floodthe time between the middle of
the rainfall event and the runoff peak.
If a stream's capacity for moving water
and sediment is diminished, or if the
sediment loads produced from the wa-
tershed become too great for the stream
to transport, flooding will occur more
frequently and the valley floor will
begin to fill. Valley filling results in the
temporary storage of sediment pro-
duced by the watershed.
Figure 1.20: Hydrologic and topographic floodplains. The hydrologic floodplain is defined by
bankfull elevation. The topographic floodplain includes the hydrologic floodplain and other lands
up to a defined elevation.
1-18
Chapter 1: Overview of Stream Corridors
-------
Lane/forms and Deposits
Topographic features are formed on the
floodplain by the lateral migration of
the channel (Figure 1.21). These fea-
tures result in varying soil and moisture
conditions and provide a variety of
habitat niches that support plant and
animal diversity.
Floodplain landforms and deposits in-
clude:
Meander scroll, a sediment formation
marking former channel
locations.
Chute, a new channel formed across
the base of a meander. As it grows in
size, it carries more of the flow.
Oxbow, a term used to describe the
severed meander after a chute is
formed.
Clay plug, a soil deposit developed at
the intersection of the oxbow and the
new main channel.
Oxbow lake, a body of water created
after clay plugs the oxbow from the
main channel.
Natural levees, formations built up
along the bank of some streams that
flood. As sediment-laden water spills
over the bank, the sudden loss of
depth and velocity causes coarser-
sized sediment to drop out of sus-
pension and collect along the edge of
the stream.
Splays, delta-shaped deposits of
coarser sediments that occur when a
natural levee is breached. Natural
levees and splays can prevent flood-
waters from returning to the channel
when floodwaters recede.
Backsivamps, a term used to describe
floodplain wetlands formed by nat-
ural levees.
I
Figure 1.21: Landforms and deposits of a floodplain. Topographic features on the floodplain
caused by meandering streams.
A Lateral View Across the Stream Corridor
1-19
-------
Transitional Upland Fringe
The transitional upland fringe serves as
a transitional zone between the flood-
plain and surrounding landscape. Thus,
its outside boundary is also the outside
boundary of the stream corridor itself.
While stream-related hydrologic and ge-
omorphic processes might have formed
a portion of the transitional upland
fringe in geologic times, they are not re-
sponsible for maintaining or altering its
present form. Consequently, land use
activities have the greatest potential to
impact this component of the stream
corridor.
There is no typical cross section for this
component. Transitional upland fringes
can be flat, sloping, or in some cases,
nearly vertical (Figure 1.22). They can
incorporate features such as hillslopes,
bluffs, forests, and prairies, often modi-
fied by land use. All transitional upland
f '
fringes have one common attribute,
however: they are distinguishable from
the surrounding landscape by their
greater connection to the floodplain
and stream.
An examination of the floodplain side
of the transitional upland fringe often
reveals one or more benches. These
landforms are called terraces (Figure
1.23). They are formed in response to
new patterns of streamflow, changes in
sediment size or load, or changes in wa-
tershed base levelthe elevation at the
watershed outlet.
Terrace formation can be explained
using the aforementioned stream bal-
ance equation (Figure 1.13). When one
or more variables change, equilibrium
is lost, and either degradation or aggra-
dation occurs.
Figure 1.24 presents an example of ter-
race formation by channel incision.
Cross section A represents a nonincised
channel. Due to changes in streamflow
or sediment delivery, equilibrium is lost
Figure 1.22: Transitional upland fringe. This
component of the stream corridor is a transi-
tion zone between the floodplain and the
surrounding landscape.
Figure 1.23: Terraces formed by an incising
stream. Terraces are formed in response to
new patterns of streamflow or sediment load
in the watershed.
1-20
Chapter 1: Overview of Stream Corridors
-------
and the channel degrades and widens.
The original floodplain is abandoned
and becomes a terrace (cross section B).
The widening phase is completed when
a floodplain evolves within the
widened channel (cross section C).
Geomorphologists often classify land-
scapes by numbering surfaces from the
lowest surface up to the highest surface.
Surface 1 in most landscapes is the bot-
tom of the main channel. The next
highest surface, Surface 2, is the flood-
plain. In the case of an incising stream,
Surface 3 usually is the most recently
formed terrace, Surface 4 the next older
terrace, and so on. The numbering sys-
tem thus reflects the ages of the sur-
faces. The higher the number, the older
the surface.
Boundaries between the numbered sur-
faces are usually marked by a scarp, or
relatively steep surface. The scarp be-
tween a terrace and a floodplain is espe-
cially important because it helps
confine floods to the valley floor.
Flooding occurs much less frequently, if
at all, on terraces.
Vegetation Across the
Stream Corridor
Vegetation is an important and highly
variable element in the stream corridor.
In some minimally disturbed stream
corridors, a series of plant communities
might extend uninterrupted across the
entire corridor. The distribution of these
communities would be based on differ-
ent hydrologic and soil conditions. In
smaller streams the riparian vegetation
might even form a canopy and enclose
the channel. This and other configura-
tion possibilities are displayed in Figure
1.25.
Plant communities play a significant
role in determining stream corridor
condition, vulnerability, and potential
for (or lack of) restoration. Thus, the
A. Nonincised Stream
terrace
bankfull channel
B. Incised Stream (early widening phase)
incised, widening channel
C. Incised Stream (widening phase complete)
floodplain
channel
Figure 1.24: Terraces in (A) nonindsed and (B
and C) incised streams. Terraces are abandoned
floodplains, formed through the interplay of
incising and floodplain widening.
type, extent and distribution, soil mois-
ture preferences, elevation, species com-
position, age, vigor, and rooting depth
are all important characteristics that a
practitioner must consider when plan-
ning and designing stream corridor
restoration.
Flood-Pulse Concept
Floodplains serve as essential focal
points for the growth of many riparian
FAST
FORWARD
Preview
Chapter 2,
Section D for
more informa-
tion on plant
community
characteristics.
A Lateral View Across the Stream Corridor
1-21
-------
Closed Canopy Over Channel, Floodplain,
and Transitional Upland Fringe
^-^-c^-w
Open Canopy Over Channel
plant communities and the wildlife
they support. Some riparian plant
species such as willows and cotton-
woods depend on flooding for regener-
ation. Flooding also nourishes
floodplains with sediments and nutri-
ents and provides habitat for inverte-
brate communities, amphibians,
reptiles, and fish spawning.
The flood-pulse concept was developed
to summarize how the dynamic interac-
tion between water and land is ex-
ploited by the riverine and floodplain
biota (Figure 1.26). Applicable primar-
ily on larger rivers, the concept demon-
strates that the predictable advance and
retraction of water on the floodplain in
a natural setting enhances biological
productivity and maintains diversity
(Bayley 1995).
Figure 1.25: Examples of vegetation structure
in the stream corridor. Plant communities play
a significant role in determining the condition
and vulnerability of the stream corridor.
1-22
Chapter 1: Overview of Stream Corridors
-------
flood-tolerant trees
decomposition of
terrestrial and older
aquatic vegetation
maximum biomass
of aquatic vegetationj
runoff of
nutrients
resulting from
decomposition
consolidation of
sediments;
moist soil plant
germination
Most river-
spawning fish
start to breed.
annual
terrestrial
grasses
maximum productio
of aquatic
vegetation
Lake and river
spawning;
young-of-the-
year and
predators follow
moving littoral;
fish and
invertebrate
production high.
Young and adult
fish disperse and
feed, dissolved
oxygen (DO)
permitting.
decomposition
of stranded
aquatic vegetation,
mineralization of
nutrients
Many fish
respond to
drawdown by
finding deeper
water.
regrowth of
terrestrial
runoff and
concentration
of nutrients
resulting from
decomposition
<
grasses an
consolidation
of sediments A)
u Miruux^^^^
jr
&r
r decomposition of most
remaining vegetation
aquatic/terrestrial transition zone
(floodplain)
Fish migrate to
main channel,
permanent lakes
or tributaries.
Figure 1.26: Schematic of the flood-pulse concept. A vertically exaggerated section of a
floodplain in five snapshots of an annual hydrological cycle. The left column describes the
movement of nutrients. The right column describes typical life history traits of fish.
Source: Bayley, Bioscience, vol. 45, p.154, March 1995. ©1995 American Institute of Biological Science.
A Lateral View Across the Stream Corridor
1-23
-------
1.C A Longitudinal View Along the Stream
Corridor
The processes that develop the charac-
teristic structure seen in the lateral view
of a stream corridor also influence
structure in the longitudinal view.
Channel width and depth increase
downstream due to increasing drainage
area and discharge. Related structural
changes also occur in the channel,
floodplain, and transitional upland
fringe, and in processes such as erosion
and deposition. Even among different
types of streams, a common sequence
of structural changes is observable from
headwaters to mouth.
Longitudinal Zones
The overall longitudinal profile of most
streams can be roughly divided into
three zones (Schumm 1977). Some of
the changes in the zones are character-
ized in Figures 1.27 and 1.28.
Zone 1, or headwaters, often has the
steepest gradient. Sediment erodes from
slopes of the watershed and moves
downstream. Zone 2, the transfer zone,
receives some of the eroded material. It
is usually characterized by wide flood-
plains and meandering channel pat-
terns. The gradient flattens in Zone 3,
the primary depositional zone. Though
the figure displays headwaters as moun-
tain streams, these general patterns and
changes are also often applicable to wa-
tersheds with relatively small topo-
graphic relief from the headwaters to
mouth. It is important to note that ero-
sion, transfer, and deposition occur in
all zones, but the zone concept focuses
on the most dominant process.
Watershed Forms
All watersheds share a common defini-
tion: a watershed is an "area of land that
Mountain headwater streams
flow swiftly down steep
slopes and cut a deep
V-shaped valley.
Rapids and
waterfalls are
Low-elevation streams
merge and flow down
gentler slopes. The
valley broadens and
the river begins to
meander.
At an even lower
elevation a river wanders
and meanders slowly
across a broad, nearly flat
valley. At its mouth it may
divide into many separate
channels as it flows across
a delta built up of river-
borne sediments and into
the sea.
Figure 1.27: Three longitudinal profile zones. Channel and floodplain characteristics change as
rivers travel from headwaters to mouth.
Source: Miller (1990). ©1990 Wadsworth Publishing Co.
1-24
Chapter 1: Overview of Stream Corridors
-------
drains water, sediment, and dissolved
materials to a common outlet at some
point along a stream channel" (Dunne
and Leopold 1978). Form varies greatly,
however, and is tied to many factors
including climatic regime, underlying
geology, morphology, soils, and vegeta-
tion.
Drainage Patterns
One distinctive aspect of a watershed
when observed in planform (map view)
is its drainage pattern (Figure 1.29).
Drainage patterns are primarily con-
trolled by the overall topography and
underlying geologic structure of the
watershed.
Stream Ordering
A method of classifying, or ordering,
the hierarchy of natural channels within
a watershed was developed by Horton
(1945). Several modifications of the
original stream ordering scheme have
Transfer
Deposition
channel depth
mean flow velocity
Drainage Area (~downstream distance2)
Figure 1.28: Changes in the channel in the three zones. Flow, channel size, and sediment
characteristics change throughout the longitudinal profile.
A Longitudinal View Along the Stream Corridor
1-25
-------
Dendritic
Figure 1.29: Watershed drainage patterns.
Patterns are determined by topography and
geologic structure.
Source: A.D. Howard, AAPG © 1967, reprinted by
permission of the American Association of Petroleum
Geologists.
been proposed, but the modified sys-
tem of Strahler (1957) is probably the
most popular today.
Strahler's stream ordering system is por-
trayed in Figure 1.30. The uppermost
channels in a drainage network (i.e.,
headwater channels with no upstream
tributaries) are designated as first-order
streams down to their first confluence.
A second-order stream is formed below
the confluence of two first-order chan-
nels. Third-order streams are created
when two second-order channels join,
and so on. Note in the figure that the
intersection of a channel with another
1
'
Figure 1.30: Stream ordering in a drainage net-
work. Stream ordering is a method of classify-
ing the hierarchy of natural channels in a
watershed.
channel of lower order does not raise
the order of the stream below the inter-
section (e.g., a fourth-order stream in-
tersecting with a second-order stream is
still a fourth-order stream below the in-
tersection).
Within a given drainage basin, stream
order correlates well with other basin
parameters, such as drainage area or
channel length. Consequently, knowing
what order a stream is can provide clues
concerning other characteristics such as
which longitudinal zone it resides in
and relative channel size and depth.
Channel Form
The form of the channel can change as
it moves through the three longitudinal
zones. Channel form is typically de-
scribed by two characteristicsthread
(single or multiple) and sinuosity.
Single- and Multiple-Thread
Streams
Single-thread (one-channel) streams are
most common, but multiple-thread
streams occur in some landscapes (Fig-
ure 1.31). Multiple-thread streams are
further categorized as either braided or
anastomosed streams.
1-26
Chapter 1: Overview of Stream Corridors
-------
Three conditions tend to promote the
formation of braided streams:
Erodible banks.
An abundance of coarse sediment.
Rapid and frequent variations in dis-
charge.
Braided streams typically get their start
when a central sediment bar begins to
form in a channel due to reduced
streamflow or an increase in sediment
load. The central bar causes water to
flow into the two smaller cross sections
on either side. The smaller cross section
results in a higher velocity flow. Given
erodible banks, this causes the channels
to widen. As they do this, flow velocity
decreases, which allows another central
bar to form. The process is then re-
peated and more channels are created.
In landscapes where braided streams
occur naturally, the plant and animal
communities have adapted to frequent
and rapid changes in the channel and
riparian area. In cases where distur-
bances trigger the braiding process,
however, physical conditions might be
too dynamic for many species.
The second, less common category of
multiple-thread channels is called anas-
tomosed streams. They occur on much
flatter gradients than braided streams
and have channels that are narrow and
deep (as opposed to the wide, shallow
channels found in braided streams).
Their banks are typically made up of
fine, cohesive sediments, making them
relatively erosion-resistant.
Anastomosed streams form when the
downstream base level rises, causing a
rapid buildup of sediment. Since bank
materials are not easily erodible, the
original single-thread stream breaks up
into multiple channels. Streams entering
deltas in a lake or bay are often anasto-
mosed. Streams on alluvial fans, in con-
trast, can be braided or anastomosed.
Sinuosity
Natural channels are rarely straight.
Sinuosity is a term indicating the
amount of curvature in the channel
(Figure 1.32). The sinuosity of a reach
is computed by dividing the channel
Figure 1.31: (a) Single-thread and (b) braided
streams. Single-thread streams are most
common. Braided streams are uncommon and
usually formed in response to erodible banks,
an abundance of coarse sediment, and rapid
and frequent variations in discharge.
A Longitudinal View Along the Stream Corridor
1-27
-------
centerline length by the length of
the valley centerline. If the channel
length/valley length ratio is more
than about 1.3, the stream can be
considered meandering in form.
Sinuosity is generally related to the
product of discharge and gradient.
(b)
Low to moderate levels of sinuosity are
typically found in Zones 1 and 2 of the
longitudinal profile. Extremely sinuous
streams often occur in the broad, flat
valleys of Zone 3.
Pools and Riffles
No matter the channel form, most
streams share a similar attribute of al-
ternating, regularly spaced, deep and
shallow areas called pools and riffles
(Figure 1.33). The pools and riffles are
associated with the thalweg, which me-
anders within the channel. Pools typi-
cally form in the thalweg near the
outside bank of bends. Riffle areas usu-
ally form between two bends at the
point where the thalweg crosses over
from one side of the channel to the
other.
The makeup of the streambed plays
a role in determining pool and riffle
characteristics. Gravel and cobble-bed
streams typically have regularly spaced
pools and riffles that help maintain
channel stability in a high-energy envi-
ronment. Coarser sediment particles
are found in riffle areas while smaller
particles occur in pools. The pool-to-
pool or riffle-to-riffle spacing is nor-
mally about 5 to 7 times the channel
width at bankfull discharge (Leopold
etal. 1964).
Sand-bed streams, on the other hand,
do not form true riffles since the grain
size distribution in the riffle area is sim-
ilar to that in the pools. However, sand-
bed streams do have evenly spaced
pools. High-gradient streams also usu-
ally have pools but not riffles, but for a
different reason. In this case, water
moves from pool to pool in a stairstep
fashion.
Figure 1.32: Sinuosity: (a) low and (b) extreme.
Low to moderately sinuous streams are usually
found in Zones 1 and 2 of the longitudinal pro-
file. Extremely sinuous streams are more typical
of Zone 3.
1-28
Chapter 1: Overview of Stream Corridors
-------
Vegetation Along the Stream
Corridor
Vegetation is an important and highly
variable element in the longitudinal as
well as the lateral view. Floodplains are
narrow or nonexistent in Zone 1 of the
longitudinal profile; thus flood-depen-
dent or tolerant plant communities
tend to be limited in distribution. Up-
land plant communities, such as forests
on moderate to steep slopes in the east-
ern or northwestern United States,
might come close to bordering the
stream and create a canopy that leaves
little open sky visible from the channel.
In other parts of the country, headwa-
ters in flatter terrain may support plant
communities dominated by grasses and
broad-leaved herbs, shrubs, or planted
vegetation.
Despite the variation in plant commu-
nity type, many headwaters areas pro-
vide organic matter from vegetation
along with the sediment they export to
Zones 2 and 3 downstream. For exam-
ple, logs and woody debris from head-
waters forests are among the most
ecologically important features support-
ing food chains and instream habitat
structure in Pacific Northwest rivers
from the mountains to the sea (Maser
and Sedell 1994).
Zone 2 has a wider and more complex
floodplain and larger channel than
Zone 1. Plant communities associated
with floodplains at different elevations
might vary due to differences in soil
type, flooding frequency, and soil mois-
ture. Localized differences in erosion
and deposition of sediment add com-
plexity and diversity to the types of
plant communities that become
established.
The lower gradient, larger stream size,
and less steep terrain in Zone 2 often
attract more agricultural or residential
development than in the headwaters
riffle
riffle
or cross over
Figure 1.33: Sequence of pools and riffles in
(a) straight and (b) sinuous streams. Pools
typically form on the outside bank of bends
and riffles in the straight portion of the chan-
nel where the thalweg crosses over from one
side to the other.
zone. This phenomenon frequently
counteracts the natural tendency to de-
velop broad and diverse stream corridor
plant communities in the middle and
lower reaches. This is especially true
when land uses involve clearing the
native vegetation and narrowing the
corridor.
Often, a native plant community is re-
placed by a planted vegetation commu-
nity such as agricultural crops or
residential lawns. In such cases, stream
processes involving flooding,
erosion/deposition, import or export of
organic matter and sediment, stream
corridor habitat diversity, and water
quality characteristics are usually signif-
icantly altered.
The lower gradient, increased sediment
deposition, broader floodplains, and
greater water volume in Zone 3 all set
the stage for plant communities differ-
ent from those found in either up-
stream zone. Large floodplain wetlands
become prevalent because of the gener-
ally flatter terrain. Highly productive
and diverse biological communities,
A Longitudinal View Along the Stream Corridor
1-29
-------
such as bottomland hardwoods, estab-
lish themselves in the deep, rich alluvial
soils of the floodplain. The slower flow
in the channel also allows emergent
marsh vegetation, rooted floating or
free-floating plants, and submerged
aquatic beds to thrive.
The changing sequence of plant com-
munities along streams from source to
mouth is an important source of biodi-
versity and resiliency to change. Al-
though many, or perhaps most, of a
stream corridor's plant communities
might be fragmented, a continuous cor-
ridor of native plant communities is de-
sirable. Restoring vegetative connectivity
in even a portion of a stream will usu-
ally improve conditions and increase its
beneficial functions.
The River Continuum Concept
The River Continuum Concept is an at-
tempt to generalize and explain longitu-
dinal changes in stream ecosystems
(Figure 1.34) (Vannote et al. 1980).
This conceptual model not only helps
to identify connections between the wa-
tershed, floodplain, and stream systems,
but it also describes how biological
communities develop and change from
the headwaters to the mouth. The River
Continuum Concept can place a site or
reach in context within a larger water-
shed or landscape and thus help practi-
tioners define and focus restoration
goals.
The River Continuum Concept hypoth-
esizes that many first- to third-order
headwater streams are shaded by the ri-
parian forest canopy. This shading, in
turn, limits the growth of algae, peri-
phyton, and other aquatic plants. Since
energy cannot be created through pho-
tosynthesis (autotrophic production),
the aquatic biota in these small streams
is dependent on allochthonous materials
(i.e., materials coming from outside the
channel such as leaves and twigs).
Biological communities are uniquely
adapted to use externally derived or-
ganic inputs. Consequently, these
headwater streams are considered
heterotrophic (i.e., dependent on the
energy produced in the surrounding
watershed). Temperature regimes are
also relatively stable due to the influ-
ence of ground water recharge, which
tends to reduce biological diversity to
those species with relatively narrow
thermal niches.
Predictable changes occur as one pro-
ceeds downstream to fourth-, fifth-,
and sixth-order streams. The channel
widens, which increases the amount
of incident sunlight and average tem-
peratures. Levels of primary production
increase in response to increases in
light, which shifts many streams to a
dependence on autochthonous materials
(i.e., materials coming from inside
the channel), or internal autotrophic
production (Minshall 1978).
In addition, smaller, preprocessed or-
ganic particles are received from up-
stream sections, which serves to balance
autotrophy and heterotrophy within the
stream. Species richness of the inverte-
brate community increases as a variety
of new habitat and food resources ap-
pear. Invertebrate functional groups,
such as the grazers and collectors, in-
crease in abundance as they adapt to
using both autochthonous and al-
lochthonous food resources. Midsized
streams also decrease in thermal stabil-
ity as temperature fluctuations increase,
which further tends to increase biotic
diversity by increasing the number of
thermal niches.
Larger streams and rivers of seventh to
twelfth order tend to increase in physi-
cal stability, but undergo significant
changes in structure and biological func-
tion. Larger streams develop increased
reliance on primary productivity by
1-30
Chapter 1: Overview of Stream Corridors
-------
grazers
_o
N
E
ro
01
10
11
12
periphyton \ course
particulate
matter
course
particulate
matter
Relative Channel Width
Figure 1.34: The River Continuum Concept. The concept proposes a relationship between
stream size and the progressive shift in structural and functional attributes.
Source: Vannote et al. (1980). Published with the permission of NRC Research Press.
A Longitudinal View Along the Stream Corridor
1-31
-------
phytoplankton, but continue to receive
heavy inputs of dissolved and ultra-fine
organic particles from upstream. Inver-
tebrate populations are dominated by
fine-particle collectors, including zoo-
plankton. Large streams frequently carry
increased loads of clays and fine silts,
which increase turbidity, decrease light
penetration, and thus increase the sig-
nificance of heterotrophic processes.
The influence of storm events and ther-
mal fluctuations decrease in frequency
and magnitude, which increases the
overall physical stability of the stream.
This stability increases the strength of
biological interactions, such as competi-
tion and predation, which tends to
eliminate less competitive taxa and
thereby reduce species richness.
The fact that the River Continuum Con-
cept applies only to perennial streams is
a limitation. Another limitation is that
disturbances and their impacts on the
river continuum are not addressed by
the model. Disturbances can disrupt the
connections between the watershed and
its streams and the river continuum as
well.
The River Continuum Concept has not
received universal acceptance due to
these and other reasons (Statzner and
Higler 1985, Junk et al. 1989). Never-
theless, it has served as a useful concep-
tual model and stimulated much
research since it was first introduced
in 1980.
1-32
Chapter 1: Overview of Stream Corridors
-------
Stream Corrido
Processes and
haracteristics
***
-------
2.A Hydrologic and Hydraulic Processes
Where does stream flow come from?
What processes affect or are involved with stream flow?
How fast, how much, how deep, how often and when does water flow?
How is hydrology different in urban stream corridors?
2.B Geomorphic Processes
What factors affect the channel cross section and channel profiler
How are water and sediment related?
Where does sediment come from and how is it transported downstream?
What is an equilibrium channel?
What should a channel look like in cross section and in profile?
How do channel adjustments occur?
What is a floodplain?
Is there an important relationship between a stream and its floodplain?
2.C Chemical Processes
What are the major chemical constituents of water?
What are some important relationships between physical habitat and key
chemical parameters?
How are the chemical and physical parameters critical to the aquatic life in a
stream corridor?
What are the natural chemical processes in a stream corridor and water column?
How do disturbances in the stream corridor affect the chemical characteristics of
stream water?
2.D Biological Processes
What are the important biological components of a stream corridor?
What biological activities and organisms can be found within a stream corridor?
How does the structure of stream corridors support various populations of organisms?
What are the structural features of aquatic systems that contribute to the biological diversity
of stream corridors?
What are some important biological processes that occur within a stream corridor?
What role do fish have in stream corridor restoration?
2.E Stream Corridor Functions and Dynamic Equilibrium
What are the major ecological functions of stream corridors?
How are these ecological functions maintained over time?
Is a stream corridor stable?
Are these functions related?
How does a stream corridor respond to all the natural forces acting on it
(i.e., dynamic equilibrium)?
-------
Stream
Corridor
Processes,
Characteristics,
and Functions
2.A Hydrologic and Hydraulic Processes
2.B Geomorphic Processes
2.C Physical and Chemical Characteristics
2.D Biological Community Characteristics
2.E Functions and Dynamic Equilibrium
Chapter 1 provided an overview of
stream corridors and the many per-
spectives from which they should be
viewed in terms of scale, equilibrium, and
space. Each of these views can be seen as
a "snapshot" of different aspects of a
stream corridor.
Chapter 2 presents the stream corridor in
motion, providing a basic understanding
of the different processes that make the
stream corridor look and function the way
it does. While Chapter 1 presented still
images, this chapter provides "film
footage" to describe the processes, char-
acteristics, and functions of stream corri-
dors through time.
Section 2.A: Hydrologic and Hydraulic
Processes
Understanding how water flows into and
through stream corridors is critical to
restorations. How fast, how much, how
deep, how often, and when water
flows are important
basic questions that
must be answered to
Figure 2.1: A stream corridor in
motion. Processes, characteris-
tics, and functions shape stream
corridors and make them look
the way they do.
-------
make appropriate decisions about
stream corridor restoration.
Section 2.B: Geomorphic Processes
This section combines basic hydro-
logic processes with physical or
geomorphic functions and charac-
teristics. Water flows through
streams but is affected by the kinds
of soils and alluvial features within
the channel, in the floodplain, and
in the uplands. The amount and
kind of sediments carried by a
stream largely determines its equi-
librium characteristics, including
size, shape, and profile. Successful
stream corridor restoration,
whether active (requiring direct
changes) or passive (management
and removal of disturbance fac-
tors), depends on an understanding
of how water and sediment are re-
lated to channel form and function
and on what processes are involved
with channel evolution.
Section 2.C: Physical and Chemical
Characteristics
The quality of water in the stream
corridor is normally a primary ob-
jective of restoration, either to im-
prove it to a desired condition, or
to sustain it. Restoration should
consider the physical and chemical
characteristics that may not be
readily apparent but that are
nonetheless critical to the functions
and processes of stream corridors.
Changes in soil or water chemistry
to achieve restoration goals usually
involve managing or altering ele-
ments in the landscape or corridor.
Section 2.D: Biological Community
Characteristics
The fish, wildlife, plants, and hu-
mans that use, live in, or just visit
the stream corridor are key ele-
ments to consider in restoration.
Typical goals are to restore, create,
enhance, or protect habitat to ben-
efit life. It is important to under-
stand how water flows, how
sediment is transported, and how
geomorphic features and processes
evolve; however, a prerequisite to
successful restoration is an under-
standing of the living parts of the
system and how the physical and
chemical processes affect the
stream corridor.
Section 2.E: Functions and
Dynamic Equilibrium
The six major functions of stream
corridors are: habitat, conduit,
barrier, filter, source, and sink.
The integrity of a stream corridor
ecosystem depends on how well
these functions operate. This
section discusses these functions
and how they relate to dynamic
equilibrium.
2-2
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
2.A Hydrologic and Hydraulic Processes
SBfe^n ^^^BPB***^"^*^^^'''^'^^^MBI!
gions that experience seasonal cycles of
snowfall and snowmelt.
The type of precipitation that will occur
is generally a factor of humidity and air
temperature. Topographic relief and ge-
ographic location relative to large water
bodies also affect the frequency and
type of precipitation. Rainstorms occur
more frequently along coastal and low-
latitude areas with moderate tempera-
tures and low relief. Snowfalls occur
more frequently at high elevations and
in mid-latitude areas with colder sea-
sonal temperatures.
The hydrologic cycle describes the contin-
uum of the transfer of water from pre-
cipitation to surface water and ground
water, to storage and runoff, and to the
eventual return to the atmosphere by
transpiration and evaporation (Figure
2.2).
Precipitation returns water to the earth's
surface. Although most hydrologic
processes are described in terms of rain-
fall events (or storm events), snowmelt
is also an important source of water, es-
pecially for rivers that originate in high
mountain areas and for continental re-
c^ deep percolation
Figure 2.2: The hydrologic cycle. The transfer of water from precipitation to surface water and
ground water, to storage and runoff, and eventually back to the atmosphere is an ongoing cycle.
Hydrologic and Hydraulic Processes
2-3
-------
Precipitation can do one of three things
once it reaches the earth. It can return
to the atmosphere; move into the soil;
or run off the earth's surface into a
stream, lake, wetland, or other water
body. All three pathways play a role in
determining how water moves into,
across, and down the stream
corridor.
This section is divided into two subsec-
tions. The first subsection focuses on
hydrologic and hydraulic processes in
the lateral dimension, namely, the
movement of water from the land into
the channel. The second subsection
concentrates on water as it moves in the
longitudinal dimension, specifically as
streamflow in the channel.
Hydrologic and Hydraulic
Processes Across the Stream
Corridor
Key points in the hydrologic cycle serve
as organizational headings in this sub-
section:
Interception, transpiration, and
evapotranspiration.
Infiltration, soil moisture, and
ground water.
Runoff.
Interception, Transpiration, and
Evapotranspiration
More than two-thirds of the precipita-
tion falling over the United States evap-
orates to the atmosphere rather than
being discharged as streamflow to the
oceans. This "short-circuiting" of the
hydrologic cycle occurs because of the
two processes, interception and transpi-
ration.
Interception
A portion of precipitation never reaches
the ground because it is intercepted by
vegetation and other natural and con-
structed surfaces. The amount of water
intercepted in this manner is determined
by the amount of interception storage
available on the above-ground surfaces.
In vegetated areas, storage is a function
of plant type and the form and density
of leaves, branches, and stems (Table
2.1). Factors that affect storage in
forested areas include:
Leaf shape. Conifer needles hold
water more efficiently than leaves.
On leaf surfaces droplets run togeth-
er and roll off. Needles, however,
keep droplets separated.
Leaf texture. Rough leaves store more
water than smooth leaves.
Time of year. Leafless periods provide
less interception potential in the
canopy than growing periods; howev-
er, more storage sites are created by
leaf litter during this time.
Vertical and horizontal density. The
more layers of vegetation that precip-
itation must penetrate, the less likely
it is to reach the soil.
Age of the plant community. Some
vegetative stands become more dense
with age; others become less dense.
The intensity, duration, and frequency
of precipitation also affect levels of in-
terception.
Figure 2.3 shows some of the pathways
rainfall can take in a forest. Rainfall at
Table 2.1: Percentage of precipitation inter-
cepted for various vegetation types.
Source: Dunne and Leopold 1978.
Vegetative Type I % Precipitation Intercepted
Forests
Deciduous
Coniferous
Crops
Alfalfa
Corn
Oats
Grasses
13
28
"Z3
36
16
L 7
10-20
2-4
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
the beginning of a storm initially fills
interception storage sites in the canopy.
As the storm continues, water held in
these storage sites is displaced. The dis-
placed water drops to the next lower
layer of branches and limbs and fills
storage sites there. This process is re-
peated until displaced water reaches the
lowest layer, the leaf litter. At this point,
water displaced off the leaf litter either
infiltrates the soil or moves downslope
as surface runoff.
Antecedent conditions, such as mois-
ture still held in place from previous
storms, affect the ability to intercept
and store additional water. Evaporation
will eventually remove water residing
in interception sites. How fast this
process occurs depends on climatic
conditions that affect the evaporation
rate.
Interception is usually insignificant in
areas with little or no vegetation. Bare
soil or rock has some small imperme-
able depressions that function as inter-
ception storage sites, but typically most
of the precipitation either infiltrates the
soil or moves downslope as surface
runoff. In areas of frozen soil, intercep-
tion storage sites are typically filled
with frozen water. Consequently, addi-
tional rainfall is rapidly transformed
into surface runoff.
Interception can be significant in large
urban areas. Although urban drainage
systems are designed to quickly move
storm water off impervious surfaces, the
urban landscape is rich with storage
sites. These include flat rooftops, park-
ing lots, potholes, cracks, and other
rough surfaces that can intercept and
hold water for eventual evaporation.
Transpiration and Evapotranspiration
Transpiration is the diffusion of water
vapor from plant leaves to the atmos-
phere. Unlike intercepted water, which
originates from precipitation, transpired
precipitation
canopy
interception
and evaporation
litter
interception
and
evaporation
mineral soil
rainfall entering
the soil
Figure 2.3: Typical pathways for forest rainfall.
A portion of precipitation never reaches the
ground because it is intercepted by vegetation
and other surfaces.
water originates from water taken in by
roots.
Transpiration from vegetation and evap-
oration from interception sites and
open water surfaces, such as ponds and
lakes, are not the only sources of water
returned to the atmosphere. Soil mois-
ture also is subject to evaporation.
Evaporation of soil moisture is, how-
ever, a much slower process due to cap-
illary and osmotic forces that keep the
moisture in the soil and the fact that
vapor must diffuse upward through soil
pores to reach surface air at a lower
vapor pressure.
Because it is virtually impossible to sep-
arate water loss due to transpiration
Hydrologic and Hydraulic Processes
2-5
-------
Evaporation
Water is subject to evaporation whenever it is
exposed to the atmosphere. Basically this process
involves:
The change of state of water from liquid to
vapor
The net transfer of this vapor to the atmosphere
The process begins when some molecules in the
liquid state attain sufficient kinetic energy (primari-
ly from solar energy) to overcome the forces of
surface tension and move into the atmosphere.
This movement creates a vapor pressure in the
atmosphere.
The net rate of movement is proportional to the
difference in vapor pressure between the water
surface and the atmosphere above that surface.
Once the pressure is equalized, no more evapora-
tion can occur until new air, capable of holding
more water vapor, displaces the old saturated air.
Evaporation rates therefore vary according to lati-
tude, season, time of day, cloudiness, and wind
energy. Mean annual lake evaporation in the
United States, for example, varies from 20 inches
in Maine and Washington to about 86 inches in
the desert Southwest (Figure 2.4).
<20 inches
20-30 inches
30-40 inches
D 40-50 inches
CH 50-60 inches
CZ1 60-70 inches
CH 70-80 inches
I I >80 inches
Figure 2.4: Mean annual lake evaporation for the period 1946-1955.
Source: Dunne and Leopold (1978) modified from Kohler et al. (1959).
2-6
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
from water loss due to evaporation, the
two processes are commonly combined
and labeled evapotranspiration. Evapo-
transpiration can dominate the water
balance and can control soil moisture
content, ground water recharge, and
streamflow.
The following concepts are important
when describing evapotranspiration:
If soil moisture conditions are limit-
ing, the actual rate of evapotranspira-
tion is below its potential rate.
When vegetation loses water to the
atmosphere at a rate unlimited by
the supply of water replenishing the
roots, its actual rate of evapotranspi-
ration is equal to its potential rate of
evapotranspiration.
The amount of precipitation in a region
drives both processes, however. Soil
types and rooting characteristics also
play important roles in determining the
actual rate of evapotranspiration.
Infiltration, Soil Moisture, and
Ground Water
Precipitation that is not intercepted or
flows as surface runoff moves into the
soil. Once there, it can be stored in the
upper layer or move downward through
the soil profile until it reaches an area
completely saturated by water called the
phreatic zone.
Infiltration
Close examination of the soil surface re-
veals millions of particles of sand, silt,
and clay separated by channels of differ-
ent sizes (Figure 2.5). These macropores
include cracks, "pipes" left by decayed
roots and wormholes, and pore spaces
between lumps and particles of soil.
Water is drawn into the pores by gravity
and capillary action. Gravity is the
dominant force for water moving into
the largest openings, such as worm or
root holes. Capillary action is the domi-
dry
grains
-
JC r
< wetted
grains
Figure 2.5: Soil profile. Water is drawn into the
pores in soil by gravity and capillary action.
Hydrologic and Hydraulic Processes
2-7
-------
rainfall
.75 inches/hr
rainfall
1.5 inches/hr
infiltration
.75 inches/hr
A.
Infiltration Rate =
rainfall rate, which is less than
infiltration capacity
infiltration
inch/hr
B. Runoff Rate =
rainfall rate minus
infiltration capacity
Figure 2.6: Infiltration and runoff. Surface runoff occurs when rainfall intensity exceeds infiltration
capacity.
nant force for water moving into soils
with very fine pores.
The size and density of these pore
openings determine the water's rate of
entry into the soil. Porosity is the term
used to describe the percentage of the
total soil volume taken up by spaces be-
tween soil particles. When all those
spaces are filled with water, the soil is
said to be saturated.
Soil characteristics such as texture and
tilth (looseness) are key factors in deter-
mining porosity. Coarse-textured, sandy
soils and soils with loose aggregates
held together by organic matter or small
amounts of clay have large pores and,
thus, high porosity. Soils that are tightly
packed or clayey have low porosity.
Infiltration is the term used to describe
the movement of water into soil pores.
The infiltration rate is the amount of
water that soaks into soil over a given
length of time. The maximum rate that
water infiltrates a soil is known as the
soil's infiltration capacity.
If rainfall intensity is less than infiltra-
tion capacity, water infiltrates the soil at
a rate equal to the rate of rainfall. If the
rainfall rate exceeds the infiltration ca-
pacity, the excess water either is de-
tained in small depressions on the soil
surface or travels downslope as surface
runoff (Figure 2.6).
The following factors are important in
determining a soil's infiltration rate:
Ease of entry through the soil surface.
Storage capacity within the soil.
Transmission rate through the soil.
Areas with natural vegetative cover and
leaf litter usually have high infiltration
rates. These features protect the surface
soil pore spaces from being plugged by
fine soil particles created by raindrop
splash. They also provide habitat for
worms and other burrowing organisms
and provide organic matter that helps
bind fine soil particles together. Both of
these processes increase porosity and
the infiltration rate.
The rate of infiltration is not constant
throughout the duration of a storm.
The rate is usually high at the begin-
ning of a storm but declines rapidly as
gravity-fed storage capacity is filled.
A slower, but stabilized, rate of infiltra-
tion is reached typically 1 or 2 hours
into a storm. Several factors are in-
2-8
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
volved in this stabilization process,
including the following:
Raindrops breaking up soil aggregates
and producing finer material, which
then blocks pore openings on the sur-
face and reduces the ease of entry.
Water filling fine pore spaces and
reducing storage capacity.
Wetted clay particles swelling and
effectively reducing the diameter of
pore spaces, which, in turn, reduces
transmission rates.
Soils gradually drain or dry following a
storm. However, if another storm occurs
before the drying process is completed,
there is less storage space for new water.
Therefore, antecedent moisture condi-
tions are important when analyzing
available storage.
Soil Moisture
After a storm passes, water drains out of
upper soils due to gravity. The soil re-
mains moist, however, because some
amount of water remains tightly held in
fine pores and around particles by sur-
face tension. This condition, called field
capacity, varies with soil texture. Like
porosity, it is expressed as a proportion
by volume.
The difference between porosity and
field capacity is a measure of unfilled
pore space (Figure 2.7). Field capacity
is an approximate number, however, be-
cause gravitation drainage continues in
moist soil at a slow rate.
Soil moisture is most important in the
context of evapotranspiration. Terrestrial
plants depend on water stored in soil.
As their roots extract water from pro-
gressively finer pores, the moisture con-
tent in the soil may fall below the field
capacity. If soil moisture is not replen-
ished, the roots eventually reach a point
where they cannot create enough suc-
tion to extract the tightly held interstitial
0.60
0.50
0.40
E
I
0.30
o
'
I
0.20
0.10
porosity
field
capacity
wilting
point
clay
heavy
clay loam
clay loam
light clay loam
silt loam
Figure 2.7: Water-holding properties of various
soils. Water-holding properties vary by texture.
For a fine sandy loam the approximate differ-
ence between porosity, 0.45, and field capacity,
0.20, is 0.25, meaning that the unfilled pore
space is 0.25 times the soil volume. The differ-
ence between field capacity and wilting point is
a measure of unfilled pore space.
Source: Dunne and Leopold 1978.
pore water. The moisture content of the
soil at this point, which varies depend-
ing on soil characteristics, is called the
permanent wilting point because plants
can no longer withdraw water from the
soil at a rate high enough to keep up
with the demands of transpiration, caus-
ing the plants to wilt.
Deep percolation is the amount of water
that passes below the root zone of
crops, less any upward movement of
water from below the root zone (Jensen
et al. 1990).
Ground Water
The size and quantity of pore openings
also determines the movement of water
within the soil profile. Gravity causes
Hydrologic and Hydraulic Processes
2-9
-------
water to move vertically downward.
This movement occurs easily through
larger pores. As pores reduce in size due
to swelling of clay particles or filling of
pores, there is a greater resistance to
flow. Capillary forces eventually take
over and cause water to move in any
direction.
Water will continue to move downward
until it reaches an area completely satu-
rated with water, the phreatic zone or
zone of saturation (Figure 2.8). The top
of the phreatic zone defines the ground
water table or phreatic surface. Just
above the ground water table is an area
called the capillary fringe, so named be-
cause the pores in this area are filled
with water held by capillary forces.
In soils with tiny pores, such as clay or
silt, the capillary forces are strong. Con-
sequently, the capillary fringe can ex-
tend a large distance upward from the
water table. In sandstone or soils with
large pores, the capillary forces are weak
and the fringe narrow.
Between the capillary fringe and the soil
surface is the vadose zone, or the zone of
aeration. It contains air and microbial
respiratory gases, capillary water, and
water moving downward by gravity to
the phreatic zone. Pellicular water is the
film of ground water that adheres to in-
dividual particles above the ground
water table. This water is held above the
capillary fringe by molecular attraction.
If the phreatic zone provides a consis-
tent supply of water to wells, it is
known as an aquifer. Good aquifers
usually have a large lateral and vertical
extent relative to the amount of water
withdrawn from wells and high poros-
ity, which allows water to drain easily.
The opposite of an aquifer is an
aquitard or confining bed. Aquitards or
confining beds are relatively thin sedi-
ment or rock layers that have low per-
meability. Vertical water movement
through an aquitard is severely re-
stricted. If an aquifer has no confining
layer overlying it, it is known as an
unconfined aquifer. A confined aquifer is
one confined by an aquitard.
The complexity and diversity of aquifers
and aquitards result in a multitude of
Figure 2.8: Ground
water related fea-
tures and terminolo-
gy. Ground water
elevation along the
stream corridor can
vary significantly over
short distances,
depending on subsur-
face characteristics.
Source: USGS Water
Supply Paper #1988,
1972, Definitions of
Selected Ground Water
Terms.
potentimetric flowing perched water water table land
surface artesian table and aquifer well surface
well . | |osing
gaining \ ^^. stream
stream
capillary
vadose zone fringe
ground water
(phreatic water)
aquitard
bedrock
2-10
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
underground scenarios. For example,
perched ground water occurs when a shal-
low aquitard of limited size prevents
water from moving down to the
phreatic zone. Water collects above the
aquitard and forms a "mini-phreatic
zone." In many cases, perched ground
water appears only during a storm or
during the wet season. Wells tapping
perched ground water may experience a
shortage of water during the dry season.
Perched aquifers can, however, be im-
portant local sources of ground water.
Artesian wells are developed in con-
fined aquifers. Because the hydrostatic
pressure in confined aquifers is greater
than atmospheric pressure, water levels
in artesian wells rise to a level where at-
mospheric pressure equals hydrostatic
pressure. If this elevation is above the
ground surface, water can flow freely
out of the well.
Water also will flow freely where the
ground surface intersects a confined
aquifer. The piezometric surface is the
level to which water would rise in wells
tapped into confined aquifers if the
wells extended indefinitely above the
ground surface. Phreatic wells draw
water from below the phreatic zone in
unconfined aquifers. The water level in
a phreatic well is the same as the
ground water table.
Practitioners of stream corridor restora-
tion should be concerned with locations
where ground water and surface water
are exchanged. Areas that freely allow
movement of water to the phreatic zone
are called recharge areas. Areas where the
water table meets the soil surface or
where stream and ground water emerge
are called springs or seeps.
The volume of ground water and the
elevation of the water table fluctuate
according to ground water recharge
and discharge. Because of the fluctua-
tion of water table elevation, a stream
channel can function either as a
recharge area (influent or "losing"
stream) or a discharge area (effluent
or "gaining" stream).
Runoff
When the rate of rainfall or snowmelt
exceeds infiltration capacity, excess
water collects on the soil surface and
travels downslope as runoff. Factors
that affect runoff processes include cli-
mate, geology, topography, soil charac-
teristics, and vegetation. Average annual
runoff in the contiguous United States
ranges from less than 1 inch to more
than 20 inches (Figure 2.9).
Three basic types of runoff are intro-
duced in this subsection (Figure 2.10):
Overland flow
Subsurface flow
Saturated overland flow
Each of these runoff types can occur in-
dividually or in some combination in
the same locale.
Overland Flow
When the rate of precipitation exceeds
the rate of infiltration, water collects on
the soil surface in small depressions
(Figure 2.11). The water stored in these
spaces is called depression storage. It
eventually is returned to the atmos-
phere through evaporation or infiltrates
the soil surface.
After depression storage spaces are filled,
excess water begins to move downslope
as overland flow, either as a shallow
sheet of water or as a series of small
rivulets or rills. Horton (1933) was the
first to describe this process in the liter-
ature. The term Horton overland flow or
Hortonian flow is commonly used.
The sheet of water increases in depth
and velocity as it moves downhill. As it
travels, some of the overland flow is
trapped on the hillside and is called sur-
Hydrologic and Hydraulic Processes
2-11
-------
<1 inch
1-10 inches
10-20 inches
>20 inches
Figure 2.9: Average
annual runoff in the
contiguous United
States. Average
annual runoff varies
with regions.
Source: USGS 1986.
face detention. Unlike depression stor-
age, which evaporates to the atmos-
phere or enters the soil, surface
detention is only temporarily detained
from its journey downslope. It eventu-
ally runs off into the stream and is still
considered part of the total volume of
overland flow.
Overland flow typically occurs in urban
and suburban settings with paved and
impermeable surfaces. Paved areas and
soils that have been exposed and com-
pacted by heavy equipment or vehicles
are also prime settings for overland
flow. It is also common in areas of thin
soils with sparse vegetative cover such
as in mountainous terrain of arid or
semiarid regions.
Subsurface Flow
Once in the soil, water moves in re-
sponse to differences in hydraulic head
(the potential for flow due to the gradi-
ent of hydrostatic pressure at different
elevations). Given a simplified situa-
tion, the water table before a rainstorm
has a parabolic surface that slopes to-
ward a stream. Water moves downward
and along this slope and into the
stream channel. This portion of the
flow is the baseflow. The soil below the
water table is, of course, saturated. As-
suming the hill slope has uniform soil
characteristics, the moisture content of
surface soils diminishes with distance
from the stream.
During a storm, the soil nearest the
stream has two important attributes as
compared to soil upslopea higher
moisture content and a shorter distance
to the water table. These attributes cause
the water table to rise more rapidly in
response to rainwater infiltration and
causes the water table to steepen. Thus a
new, storm-generated ground water
component is added to baseflow. This
new component, called subsurface flow,
mixes with baseflow and increases
ground water discharge to the channel.
2-12
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
water
table
In some situations, infiltrated storm
water does not reach the phreatic zone
because of the presence of an aquitard.
In this case, subsurface flow does not
mix with baseflow, but also discharges
water into the channel. The net result,
whether mixed or not, is increased
channel flow.
Saturated Overland Flow
If the storm described above continues,
the slope of the water table surface can
continue to steepen near the stream.
Eventually, it can steepen to the point
that the water table rises above the
channel elevation. Additionally, ground
water can break out of the soil and
travel to the stream as overland flow.
This type of runoff is termed quick return
flow.
The soil below the ground water break-
out is, of course, saturated. Conse-
quently, the maximum infiltration rate
is reached, and all of the rain falling
on it flows downslope as overland
runoff. The combination of this direct
precipitation and quick return flow is
called saturated overland flow. As the
storm progresses, the saturated area ex-
pands further up the hillside. Because
quick return flow and subsurface flow
are so closely linked to overland flow,
they are normally considered part of
the overall runoff of surface water.
Hydrologic and Hydraulic
Processes Along the Stream
Corridor
Water flowing in streams is the collection
of direct precipitation and water that
has moved laterally from the land into
the channel. The amount and timing of
this lateral movement directly influences
Figure 2.11: Overland flow and depression
storage. Overland moves downslope as an
irregular sheet.
Source: Dunne and Leopold 1978.
Figure 2.10: Flow
paths of water over
a surface. The por-
tion of precipitation
that runs off or
infiltrates to the
ground water table
depends on the soil's
permeability rate;
surface roughness;
and the amount,
duration, and intensi-
ty of precipitation.
surface
detention
depth and
velocity of
overland flow
increase
downslope
depression storage
(depth of depressions
greatly exaggerated)
stream
channel
Hydrologic and Hydraulic Processes
2-13
-------
FAST
FORWARD
Preview Chap-
ter 7, Section
A for more de-
tailed informa-
tion about
flow duration
and frequency.
the amount and timing of streamflow,
which in turn influences ecological
functions in the stream corridor.
Flow Analysis
Flows range from no flow to flood flows
in a variety of time scales. On a broad
scale, historical climate records reveal
occasional persistent periods of wet and
dry years. Many rivers in the United
States, for example, experienced a de-
cline in flows during the "dust bowl"
decade in the 1930s. Another similar de-
cline in flows nationwide occurred in
the 1950s. Unfortunately, the length of
record regarding wet and dry years is
short (in geologic time), making it is
difficult to predict broad-scale persis-
tence of wet or dry years.
Seasonal variations of streamflow are
more predictable, though somewhat
complicated by persistence factors. Be-
cause design work requires using histor-
ical information (period of record) as a
basis for designing for the future, flow
15000 i-
information is usually presented in a
probability format. Two formats are es-
pecially useful for planning and design-
ing stream corridor restoration:
Flow duration, the probability a given
streamflow was equaled or exceeded
over a period of time.
Flow frequency, the probability a
given streamflow will be exceeded
(or not exceeded) in a year.
(Sometimes this concept is modified
and expressed as the average number
of years between exceeding [or not
exceeding] a given flow.)
Figure 2.12 presents an example of a
flow frequency expressed as a series of
probability curves. The graph displays
months on the x-axis and a range of
mean monthly discharges on the y-axis.
The curves indicate the probability that
the mean monthly discharge will be
less than the value indicated by the
curve. For example, on about January 1,
there is a 90 percent chance that the
S10000 -
01
S1
ns
I
b
C
o
5000
Oct. Nov. Dec. Jan. Feb. Mar. April May June July Aug. Sept.
Month
Figure 2.12: An example of monthly probability curves. Monthly probability that the mean
monthly discharge will be less than the values indicated. Yakima River near Parker, Washington.
(Data from U.S. Army Corps of Engineers.)
Source: Dunne and Leopold 1978.
2-14
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
discharge will be less than 9,000 cfs
and a 50 percent chance it will be less
than 2,000 cfs.
Ecological Impacts of Flow
The variability of streamflow is a pri-
mary influence on the biotic and abiotic
processes that determine the structure
and dynamics of stream ecosystems
(Covich 1993). High flows are impor-
tant not only in terms of sediment
transport, but also in terms of recon-
necting floodplain wetlands to the
channel.
This relationship is important because
floodplain wetlands provide spawning
and nursery habitat for fish and, later in
the year, foraging habitat for waterfowl.
Low flows, especially in large rivers,
create conditions that allow tributary
fauna to disperse, thus maintaining
populations of a single species in sev-
eral locations.
In general, completion of the life cycle
of many riverine species requires an
array of different habitat types whose
temporal availability is determined
by the flow regime. Adaptation to this
environmental dynamism allows river-
ine species to persist during periods
of droughts and floods that destroy
and recreate habitat elements (Poff
etal. 1997).
2.B Geomorphic Processes
Geomorphology is the study of surface
forms of the earth and the processes
that developed those forms. The hydro-
logic processes discussed in the previ-
ous section drive the geomorphic
processes described in this section. In
turn, the geomorphic processes are the
primary mechanisms for forming the
drainage patterns, channel, floodplain,
terraces, and other watershed and
stream corridor features discussed in
Chapter 1.
Three primary geomorphic processes
are involved with flowing water, as fol-
lows:
Erosion, the detachment of soil parti-
cles.
Sediment transport, the movement of
eroded soil particles in flowing water.
Sediment deposition, settling of erod-
ed soil particles to the bottom of a
water body or left behind as water
leaves. Sediment deposition can be
transitory, as in a stream channel
from one storm to another, or more
or less permanent, as in a larger
reservoir.
Since geomorphic processes are so
closely related to the movement of
water, this section is organized into
subsections that mirror the hydrologic
processes of surface storm water runoff
and streamflow:
Geomorphic Processes Across the
Stream Corridor
Geomorphic Processes Along the
Stream Corridor
Geomorphic Processes
2-15
-------
Geomorphic Processes Across
the Stream Corridor
The occurrence, magnitude, and distrib-
ution of erosion processes in water-
sheds affect the yield of sediment and
associated water quality contaminants
to the stream corridor.
Soil erosion can occur gradually over
a long period, or it can be cyclic or
episodic, accelerating during certain
seasons or during certain rainstorm
events (Figure 2.13). Soil erosion can
be caused by human actions or by nat-
ural processes. Erosion is not a simple
process because soil conditions are con-
tinually changing with temperature,
moisture content, growth stage and
amount of vegetation, and the human
manipulation of the soil for develop-
ment or crop production. Tables 2.2
and 2.3 show the basic processes that
influence soil erosion and the different
types of erosion found within the water-
shed.
Geomorphic Processes Along
the Stream Corridor
The channel, floodplain, terraces, and
other features in the stream corridor are
formed primarily through the erosion,
transport, and deposition of sediment
by streamflow. This subsection de-
scribes the processes involved with
transporting sediment loads down-
stream and how the channel and
floodplain adjust and evolve through
time.
Sediment Transport
Sediment particles found in the stream
channel and floodplain can be catego-
rized according to size. A boulder is the
largest particle and clay is the smallest
particle. Particle density depends on the
size and composition of the particle
(i.e., the specific gravity of the mineral
content of the particle).
No matter the size, all particles in the
channel are subject to being trans-
ported downslope or downstream.
The size of the largest particle a stream
can move under a given set of hy-
draulic conditions is referred to as
stream competence. Often, only very
high flows are competent to move the
largest particles.
Closely related to stream competence is
the concept of tractive stress, which cre-
ates lift and drag forces at the stream
boundaries along the bed and banks.
Tractive stress, also known as shear
stress, varies as a function of flow depth
and slope. Assuming constant density,
shape, and surface roughness, the larger
the particle, the greater the amount of
tractive stress needed to dislodge it and
move it downstream.
The energy that sets sediment particles
into motion is derived from the effect
of faster water flowing past slower
water. This velocity gradient happens
because the water in the main body of
flow moves faster than water flowing at
the boundaries. This is because bound-
Figure 2.13: Raindrop impact. One of many
types of erosion.
2-16
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
aries are rough and create friction as
flow moves over them which, in turn,
slows flow.
The momentum of the faster water is
transmitted to the slower boundary
water. In doing so, the faster water
tends to roll up the slower water in a
spiral motion. It is this shearing mo-
tion, or shear stress, that also moves
bed particles in a rolling motion down-
stream.
Particle movement on the channel bot-
tom begins as a sliding or rolling mo-
tion, which transports particles along
the streambed in the direction of flow
(Figure 2.14). Some particles also may
move above the bed surface by saltation,
a skipping motion that occurs when
one particle collides with another parti-
cle, causing it to bounce upward and
then fall back toward the bed.
These rolling, sliding, and skipping mo-
tions result in frequent contact of the
moving particles with the streambed
and characterize the set of moving par-
ticles known as bed load. The weight of
these particles relative to flow velocity
causes them essentially to remain in
contact with, and to be supported by,
the streambed as they move down-
stream.
Table 2.2: Erosion processes.
Raindrop impact Sheet, interill
Surface water runoff Sheet, interill, rill, ephemeral gully, classic gully
Channelized flow Rill, ephemeral gully, classic gully, wind, streambank
Classic gully, streambank, landslide, mass wasting
Wind
Streambank, lake shore
Solution, dispersion
Gravity
Wind
Ice
Chemical reactions
Table 2.3: Erosion types vs. physical processes.
Erosion Type
Sheet and rill
Interill
Rill
Wind
Ephemeral gully
Classic gully
Floodplain scour
Roadside
Streambank
Streambed
Landslide
Wave/shoreline
Urban, construction
Surface mine
Ice gouging
1 Sheet 1 Concentrated 1 Mass 1 Combination
1 Flow 1 Wasting 1 1
X X
X
X X
X X
X
X X
X
X
X X
X
X
X
X
X
x
Direction of
shear due to
decrease of
velocity
toward bed.
Tendency of
velocity to roll
an exposed
grain.
Diagram of
saltating grains.
Suggested motion of a
grain thrown up into
turbulent eddies in the
flow.
Figure 2.14: Action of water on particles near the streambed. Processes that transport bed load
sediments are a function of flow velocities, particle size, and principles of hydrodynamics.
Source: Water in Environmental Planning by Dunne and Leopold © 1978 by W.H. Freeman and Company.
Used with permission.
Geomorphic Processes
2-17
-------
-
Wash Load and Bed-Material Load
One way to differentiate the sediment load of a stream
is to characterize it based on the immediate source of
the sediment in transport. The total sediment load in a
stream, at any given time and location, is divided into
two partswash load and bed-material load. The prima-
ry source of wash load is the watershed, including sheet
and rill erosion, gully erosion, and upstream streambank
erosion. The source of bed material load is primarily the
streambed itself, but includes other sources in the water-
shed.
Wash load is composed of the finest sediment particles
in transport. Turbulence holds the wash load in suspen-
sion. The concentration of wash load in suspension is
essentially independent of hydraulic conditions in the
stream and therefore cannot be calculated using mea-
sured or estimated hydraulic parameters such as velocity
or discharge. Wash load concentration is normally a
function of supply; i.e., the stream can carry as much
wash load as the watershed and banks can deliver (for
sediment concentrations below approximately 3000
parts per million).
Bed-material load is composed of the sediment of size
classes found in the streambed. Bed-material load moves
along the streambed by rolling, sliding, or jumping, and
may be periodically entrained into the flow by turbu-
lence, where it becomes a portion of the suspended
load. Bed-material load is hydraulically controlled and
can be computed using sediment transport equations
discussed in Chapter 8.
Finer-grained particles are more easily
carried into suspension by turbulent ed-
dies. These particles are transported
within the water column and are there-
fore called the suspended load. Although
there may be continuous exchange of
sediment between the bed load and
suspended load of the river, as long as
sufficient turbulence is present.
Part of the suspended load may be col-
loidal clays, which can remain in sus-
pension for very long time periods,
depending on the type of clay and
water chemistry.
Sediment Transport Terminology
Sediment transport terminology can
sometimes be confusing. Because of
this confusion, it is important to define
some of the more frequently used
terms.
Sediment load, the quantity of sedi-
ment that is carried past any cross
section of a stream in a specified
period of time, usually a day or a
year. Sediment discharge, the mass
or volume of sediment passing a
stream cross section in a unit of
time. Typical units for sediment load
are tons, while sediment discharge
units are tons per day.
Bed-material load, part of the total
sediment discharge that is composed
of sediment particles that are the
same size as streambed sediment.
Wash load, part of the total sediment
load that is comprised of particle
sizes finer than those found in the
streambed.
Bed load, portion of the total sedi-
ment load that moves on or near the
streambed by saltation, rolling, or
sliding in the bed layer.
Suspended bed material load, portion
of the bed material load that is trans-
ported in suspension in the water
column. The suspended bed material
load and the bed load comprise the
total bed material load.
Suspended sediment discharge (or sus-
pended load), portion of the total sed-
iment load that is transported in sus-
pension by turbulent fluctuations
within the body of flowing water.
2-18
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
Measured load, portion of the total
sediment load that is obtained by the
sampler in the sampling zone.
Unmeasured load, portion of the total
sediment load that passes beneath
the sampler, both in suspension and
on the bed. With typical suspended
sediment samplers this is the lower
0.3 to 0.4 feet of the vertical.
The above terms can be combined in
a number of ways to give the total
sediment load in a stream (Table 2.4).
However, it is important not to com-
bine terms that are not compatible.
For example, the suspended load and
the bed material load are not compli-
mentary terms because the suspended
load may include a portion of the bed
material load, depending on the energy
available for transport. The total sedi-
ment load is correctly defined by the
combination of the following terms:
Total Sediment Load =
Bed Material Load + Wash Load
or
Bed Load + Suspended Load
or
Measured Load + Unmeasured Load
Sediment transport rates can be com-
puted using various equations or mod-
els. These are discussed in the Stream
Channel Restoration section of Chapter 8.
Table 2.4: Sediment load terms.
Classification System
Wash load
T3
ro
O
Based on
Mechanism
of Transport
Suspended
load
c Suspended
£ bed-material
H5 load
Based on
Particle Size
Wash load
Bed-material
load
a
Bed load
Bed load
Stream Power
One of the principal geomorphic tasks
of a stream is to transport particles out
of the watershed (Figure 2.15). In this
manner, the stream functions as a trans-
porting "machine;" and, as a machine,
its rate of doing work can be calculated
as the product of available power multi-
plied by efficiency.
Stream power can be calculated as:
Where:
9 = Stream power (foot-lbs/second-
foot)
y = Specific weight of water (Ibs/ft3)
Q = Discharge (ft3/second)
S = Slope (feet/feet)
Sediment transport rates are directly re-
lated to stream power; i.e., slope and
discharge. Baseflow that follows the
highly sinuous thalweg (the line that
marks the deepest points along the
stream channel) in a meandering
stream generates little stream power;
therefore, the stream's ability to move
sediment, sediment-transport capacity, is
limited. At higher depths, the flow fol-
lows a straighter course, which increases
slope, causing increased sediment trans-
port rates. The stream builds its cross
section to obtain depths of flow and
channel slopes that generate the sedi-
ment-transport capacity needed to
maintain the stream channel.
Runoff can vary from a watershed, ei-
ther due to natural causes or land use
practices. These variations may change
the size distribution of sediments deliv-
ered to the stream from the watershed
by preferentially moving particular par-
ticle sizes into the stream. It is not un-
common to find a layer of sand on top
of a cobble layer. This often happens
when accelerated erosion of sandy soils
Geomorphic Processes
2-19
-------
First Order Stream
Second to Fourth Order Stream
Fifth to Tenth Order Stream
average
particle size
on stream
bottom
Figure 2. 15: Particle transport. A stream's total sediment load in the total of all sediment particles
moving past a defined cross section over a specified time period. Transport rates vary according to
the mechanism of transport.
occurs in a watershed and the increased
load of sand exceeds the transport ca-
pacity of the stream during events that
move the sand into the channel.
Stream and Floodplain Stability
A question that normally arises when
considering any stream restoration ac-
tion is "Is it stable now and will it be
stable after changes are made?" The an-
swer may be likened to asking an opin-
ion on a movie based on only a few
frames from the reel. Although we often
view streams based on a limited refer-
ence with respect to time, it is impor-
tant that we consider the long-term
changes and trends in channel cross
section, longitudinal profile, and plan-
form morphology to characterize chan-
nel stability.
Achieving channel stability requires that
the average tractive stress maintains a
stable streambed and streambanks. That
is, the distribution of particle sizes in
each section of the stream remains in
equilibrium (i.e., new particles de-
posited are the same size and shape as
particles displaced by tractive stress).
Yang (1971) adapted the basic theories
described by Leopold to explain the
longitudinal profile of rivers, the forma-
tion of stream networks, riffles, and
pools, and river meandering. All these
river characteristics and sediment trans-
port are closely related. Yang (1971) de-
veloped the theory of average stream
fall and the theory of least rate of en-
ergy expenditure, based on the entropy
concept. These theories state that during
the evolution toward an equilibrium
condition, a natural stream chooses its
course of flow in such a manner that
the rate of potential energy expenditure
per unit mass of flow along its course is
a minimum.
2-20
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
Corridor Adjustments
Stream channels and their floodplains
are constantly adjusting to the water
and sediment supplied by the water-
shed. Successful restoration of degraded
streams requires an understanding of
watershed history, including both nat-
ural events and land use practices, and
the adjustment processes active in chan-
nel evolution.
Channel response to changes in water
and sediment yield may occur at differ-
ing times and locations, requiring vari-
ous levels of energy expenditure. Daily
changes in streamfiow and sediment
load result in frequent adjustment of
bedforms and roughness in many
streams with movable beds. Streams
also adjust periodically to extreme high-
and low-flow events, as floods not only
remove vegetation but create and in-
crease vegetative potential along the
stream corridor (e.g., low flow periods
allow vegetation incursion into the
channel).
Similar levels of adjustment also may
be brought about by changes in land
use in the stream corridor and the up-
land watershed. Similarly, long-term
changes in runoff or sediment yield
from natural causes, such as climate
change, wildfire, etc., or human causes,
such as cultivation, overgrazing, or
rural-to-urban conversions, may lead to
long-term adjustments in channel cross
section and planform that are fre-
quently described as channel evolution.
Stream channel response to changes in
flow and sediment load have been de-
scribed qualitatively in a number of
studies (e.g., Lane 1955, Schumm
1977). As discussed in Chapter 1, one
of the earliest relationships proposed
for explaining stream behavior was sug-
gested by Lane (1955), who related
mean annual streamfiow (Q ) and
channel slope (S) to bed-material sedi-
ment load (Q ) and median particle
size on the streambed (D ):
Q . D ~ Q S
^s 50 ^w
Lane's relationship suggests that a chan-
nel will be maintained in dynamic
equilibrium when changes in sediment
load and bed-material size are balanced
by changes in streamfiow or channel
gradient. A change in one of these vari-
ables causes changes in one or more of
the other variables such that dynamic
equilibrium is reestablished.
Additional qualitative relationships
have been proposed for interpreting be-
havior of alluvial channels. Schumm
(1977) suggested that width (b), depth
(d), and meander wavelength (L) are
directly proportional, and that channel
gradient (S) is inversely proportional to
streamfiow (QJ in an alluvial channel:
Q ~
b, d, L
Schumm (1977) also suggested that
width (b), meander wavelength (L),
and channel gradient (S) are directly
proportional, and that depth (d) and
sinuosity (P) are inversely proportional
to sediment discharge (QJ in alluvial
streams:
Q ~
b, L, S
d, P
The above two equations may be rewrit-
ten to predict direction of change in
channel characteristics, given an in-
crease or decrease in streamfiow or sedi-
ment discharge:
Q
Q-
~, d",
Preview Section
E for a further
discussion of
dynamic equi-
librium.
Q " ~ b", d+, L", S", P+
Geomorphic Processes
2-21
-------
Combining the four equations above
yields additional predictive relation-
ships for concurrent increases or de-
creases in streamflow and/or sediment
discharge:
QW+Q; - b+, d+/-, v, s+/-, p-
QW-Q; ~ b-, d+/-, L-, s+/-, P+
QW+Q; » b+/-, d-, i>, s+, p-
Channel Slope
Channel slope, a stream's longitudinal
profile, is measured as the difference in
elevation between two points in the
stream divided by the stream length be-
tween the two points. Slope is one of
the most critical pieces of design infor-
mation required when channel modifi-
cations are considered. Channel slope
directly impacts flow velocity, stream
competence, and stream power. Since
these attributes drive the geomorphic
processes of erosion, sediment trans-
port, and sediment deposition, channel
slope becomes a controlling factor in
channel shape and pattern.
Most longitudinal profiles of streams
are concave upward. As described previ-
ously in the discussion of dynamic
equilibrium, streams adjust their pro-
file and pattern to try to minimize the
time rate of expenditure of potential
energy, or stream power, present in
flowing water. The concave upward
shape of a stream's profile appears to
be due to adjustments a river makes
to help minimize stream power in a
downstream direction. Yang (1983)
applied the theory of minimum stream
power to explain why most longitudinal
streambed profiles are concave upward.
In order to satisfy the theory of mini-
mum stream power, which is a special
case of the general theory of minimum
energy dissipation rate (Yang and Song
1979), the following equation must be
satisfied:
dP
dx
Where:
P =
x =
Q =
s =
J =
= YQ
dS dQ
+ S
dx
dx
= 0
QS = Stream power
Longitudinal distance
Water discharge
Water surface or energy slope
Specific weight of water
Stream power has been defined as the
product of discharge and slope. Since
stream discharge typically increases in
a downstream direction, slope must
decrease in order to minimize stream
power. The decrease in slope in a down-
stream direction results in the concave-
up longitudinal profile.
Sinuosity is not a profile feature, but it
does affect stream slope. Sinuosity is
the stream length between two points
on a stream divided by the valley
length between the two points. For
example, if a stream is 2,200 feet long
from point A to point B, and if a valley
length distance between those two
points is 1,000 feet, that stream has a
sinuosity of 2.2. A stream can increase
its length by increasing its sinuosity,
resulting in a decrease in slope. This
impact of sinuosity on channel slope
must always be considered if channel
reconstruction is part of a proposed
restoration.
Pools and Riffles
The longitudinal profile is seldom
constant, even over a short reach. Dif-
ferences in geology, vegetation pat-
terns, or human disturbances can
result in flatter and steeper reaches
within an overall profile. Riffles occur
2-22
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
where the stream bottom is higher rel-
ative to streambed elevation immedi-
ately upstream or downstream. These
relatively deeper areas are considered
pools. At normal flow, flow velocities
decrease in pool areas, allowing fine
grained deposition to occur, and in-
crease atop riffles due to the increased
bed slope between the riffle crest and
the subsequent pool.
Longitudinal Profile Adjustments
A common example of profile adjust-
ment occurs when a dam is constructed
on a stream. The typical response to
dam construction is channel degrada-
tion downstream and aggradation up-
stream. However, the specific response
is quite complex as can be illustrated by
considering Lane's relation. Dams typi-
cally reduce peak discharges and sedi-
ment supply in the downstream reach.
According to Lane's relation, a decrease
in discharge (Q) should be offset by an
increase in slope, yet the decrease in
sediment load (Qs) should cause a de-
crease in slope. This response could be
further complicated if armoring occurs
(D5o+), which would also cause an in-
crease in slope. Impacts are not limited
to the main channel, but can include
aggradation or degradation on tribu-
taries as well. Aggradation often occurs
at the mouths of tributaries down-
stream of dams (and sometimes in the
entire channel) due to the reduction of
peak flows on the main stem. Obvi-
ously, the ultimate response will be the
result of the integration of all these
variables.
Channel Cross Sections
Figure 2.16 presents the type of infor-
mation that should be recorded when
collecting stream cross section data. In
stable alluvial streams, the high points
on each bank represent the top of the
bankfull channel.
The importance of the bankfull channel
has been established. Channel cross sec-
tions need to include enough points to
define the channel in relation to a por-
tion of the floodplain on each side. A
suggested guide is to include at least one
stream width beyond the highest point
on each bank for smaller stream corri-
dors and at least enough of the flood-
plain on larger streams to clearly define
its character in relation to the channel.
In meandering streams, the channel
cross section should be measured in
areas of riffles or crossovers. A riffle or
crossover occurs between the apexes of
two sequential meanders. The effects of
differences in resistance to erosion of
soil layers are prominent in the outside
bends of meanders, and point bars on
the insides of the meanders are con-
stantly adjusting to the water and sedi-
ment loads being moved by the stream.
The stream's cross section changes much
more rapidly and frequently in the me-
ander bends. There is more variability
in pool cross sections than in riffle
cross sections. The cross section in the
crossover or riffle area is more uniform.
Resistance to Flow and Velocity
Channel slope is an important factor in
determining streamflow velocity. Flow
velocity is used to help predict what
discharge a cross section can convey. As
discharge increases, either flow velocity,
flow area, or both must increase.
Figure 2.16:
Channel cross sec-
tion. Information
to record when
collecting stream
cross section data.
hydrologic floodplain
bankfull width
Geomorphic Processes
2-23
-------
Roughness plays an important r ole in
streams. It helps determine the depth or
stage of flow in a stream reach. As flow
velocity slows in a stream reach due to
roughness, the depth of flow has to in-
crease to maintain the volume of flow
that entered the upstream end of the
reach (a concept known as flow conti-
nuity). Typical roughness along the
boundaries of the stream includes the
following:
Sediment particles of different sizes.
Bedforms.
Bank irregularities.
The type, amount, and distribution
of living and dead vegetation.
Other obstructions.
Roughness generally increases with in-
creasing particle size. The shape and
size of instream sediment deposits, or
bedforms, also contribute to roughness.
Sand-bottom streams are good exam-
ples of how bedform roughness
changes with discharge. At very low dis-
charges, the bed of a sand stream may
be dominated by ripple bedforms. As
flow increases even more, sand dunes
may begin to appear on the bed. Each
of these bedforms increases the rough-
ness of the stream bottom, which tends
to slow velocity.
The depth of flow also increases due to
increasing roughness. If discharge con-
tinues to increase, a point is reached
when the flow velocity mobilizes the
sand on the streambed and the entire
bed converts again to a planar form.
The depth of flow may actually decrease
at this point due to the decreased
roughness of the bed. If discharge in-
creases further still, antidunes may
form. These bedforms create enough
friction to again cause the flow depth to
increase. The depth of flow for a given
discharge in sand-bed streams, there-
fore, depends on the bedforms present
when that discharge occurs.
Vegetation can also contribute to rough-
ness. In streams with boundaries con-
sisting of cohesive soils, vegetation is
usually the principal component of
roughness. The type and distribution of
vegetation in a stream corridor depends
on hydrologic and geomorphic
processes, but by creating roughness,
vegetation can alter these processes and
cause changes in a stream's form and
pattern.
Meandering streams offer some resis-
tance to flow relative to straight
streams. Straight and meandering
streams also have different distributions
of flow velocity that are affected by the
alignment of the stream, as shown in
Figure 2.17. In straight reaches of a
stream, the fastest flow occurs just
below the surface near the center of the
channel where flow resistance is lowest
(see Figure 2.17 (a) Section G). In me-
anders, velocities are highest at the out-
side edge due to angular momentum
(see Figure 2.17 (b) Section 3). The dif-
ferences in flow velocity distribution in
meandering streams result in both ero-
sion and deposition at the meander
bend. Erosion occurs at the outside of
bends (cutbanks) from high velocity
flows, while the slower velocities at the
insides of bends cause deposition on
the point bar (which also has been
called the slip-off slope).
The angular momentum of flow
through a meander bend increases the
height or super elevation at the outside
of the bend and sets up a secondary
current of flow down the face of the
cut bank and across the bottom of the
pool toward the inside of the bend. This
rotating flow is called helical flow and
the direction of rotation is illustrated
on the diagram on the previous page by
the arrows at the top and bottom of
cross sections 3 and 4 in the figure.
2-24
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
(a)
0
1
2
Section C
Section G
_L
I
I
I
I
4 6 8 10 12 14 16 18
Horizontal Distance (feet)
high
velocity
low
velocity
Figure 2.17: Velocity distribution in a
(a) straight stream branch and a (b) stream
meander. Stream flow velocities are different
through pools and riffles, in straight and
curved reaches, across the stream at any point,
and at different depths. Velocity distribution
also differs dramatically from baseflow condi-
tions through bankfull flows, and flood flows.
Source: Leopold et al. 1964. Published by permission
of Dover Publications.
The distribution of flow velocities in
straight and meandering streams is im-
portant to understand when planning
and designing modifications in stream
alignment in a stream corridor restora-
tion. Areas of highest velocities generate
the most stream power, so where such
velocities intersect the stream bound-
aries indicates where more durable pro-
tection may be needed.
As flow moves through a meander, the
bottom water and detritus in the pool
are rotated to the surface. This rotation
is an important mechanism in moving
drifting and benthic organisms past
Generalized
Velocity Distributions
predators in pools. Riffle areas are not
as deep as pools, so more turbulent
flows occur in these shallow zones. The
turbulent flow can increase the dis-
solved oxygen content of the water and
may also increase the oxidation and
volatilization of some chemical con-
stituents in water.
Another extremely important function
of roughness elements is that they cre-
ate aquatic habitat. As one example,
the deepest flow depths usually occur
at the base of cutbanks. These scour
holes or pools create very different
Geomorphic Processes
2-25
-------
habitat than occurs in the depositional
environment of the slip-off slope.
Active Channels and
Floodplains
Floodplains are built by two stream
processes, lateral and vertical accretion.
Lateral accretion is the deposition of
sediment on point bars on the insides
of bends of the stream. The stream lat-
erally migrates across the floodplain as
the outside of the meander bend
erodes and the point bar builds with
coarse-textured sediment. This naturally
occurring process maintains the cross
section needed to convey water and
sediment from the watershed. Vertical
accretion is the deposition of sediment
on flooded surfaces. This sediment
generally is finer textured than point
bar sediments and is considered to be
an overbank deposit. Vertical accretion
occurs on top of the lateral accretion
deposits in the point bars; however,
lateral accretion is the dominant
process. It typically makes up 60 to 80
percent of the total sediment deposits
in floodplains (Leopold et al. 1964).
It is apparent that lateral migration of
meanders is an important natural
process since it plays a critical role in
reshaping floodplains.
2.C Physical and Chemical Characteristics
a few key concepts that are relevant to
stream corridor restoration. The reader
is referred to other sources (e.g.,
Thomann and Mueller 1987, Mills et al.
1985) for a more detailed treatment.
As in the previous sections, the physical
and chemical characteristics of streams
are examined in both the lateral and
longitudinal perspectives. The lateral
perspective refers to the influence of the
watershed on water quality, with partic-
ular attention to riparian areas. The lon-
gitudinal perspective refers to processes
that affect water quality during trans-
port instream.
Physical Characteristics
Sediment
Section 2.B discussed total sediment
loads in the context of the evolution of
stream form and geomorphology. In ad-
dition to its role in shaping stream
form, suspended sediment plays an im-
portant role in water quality, both in
the water column and at the sediment-
water interface. In a water quality con-
The quality of water in the stream corri-
dor might be a primary objective of
restoration, either to improve it to a de-
sired condition or to sustain it. Estab-
lishing an appropriate flow regime and
geomorphology in a stream corridor
may do little to ensure a healthy ecosys-
tem if the physical and chemical charac-
teristics of the water are inappropriate.
For example, a stream containing high
concentrations of toxic materials or in
which high temperatures, low dissolved
oxygen, or other physical/chemical
characteristics are inappropriate cannot
support a healthy stream corridor. Con-
versely, poor condition of the stream
corridorsuch as lack of riparian shad-
ing, poor controls on erosion, or exces-
sive sources of nutrients and oxygen-
demanding wastecan result in degra-
dation of the physical and chemical
conditions within the stream.
This section briefly surveys some of the
key physical and chemical characteristics
of flowing waters. Stream water quality
is a broad topic on which many books
have been written. The focus here is on
2-26
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
text, sediment usually refers to soil par-
ticles that enter the water column from
eroding land. Sediment consists of par-
ticles of all sizes, including fine clay
particles, silt, and gravel. The term sedi-
mentation is used to describe the depo-
sition of sediment particles in
waterbodies.
Although sediment and its transport
occur naturally in any stream, changes
in sediment load and particle size can
have negative impacts (Figure 2.18).
Fine sediment can severely alter aquatic
communities. Sediment may clog and
abrade fish gills, suffocate eggs and
aquatic insect larvae on the bottom,
and fill in the pore space between bot-
tom cobbles where fish lay eggs. Sedi-
ment interferes with recreational
activities and aesthetic enjoyment at
waterbodies by reducing water clarity
and filling in waterbodies. Sediment
also may carry other pollutants into wa-
terbodies. Nutrients and toxic chemicals
may attach to sediment particles on
land and ride the particles into surface
waters where the pollutants may settle
with the sediment or become soluble in
the water column.
Studies have shown that fine sediment
intrusion can significantly impact the
quality of spawning habitat (Cooper
1965, Chapman 1988). Fine sediment
intrusion into streambed gravels can re-
duce permeability and intragravel water
velocities, thereby restricting the supply
of oxygenated water to developing
salmonid embryos and the removal of
their metabolic wastes. Excessive fine
sediment deposition can effectively
smother incubating eggs and entomb
alevins and fry. A sediment intrusion
model (Alonso et al. 1996) has been
developed, verified, and validated to
predict the within-redd (spawning area)
sediment accumulation and dissolved
oxygen status.
Sediment Across the Stream Corridor
Rain erodes and washes soil particles
off plowed fields, construction sites,
logging sites, urban areas, and strip-
mined lands into waterbodies. Eroding
streambanks also deposit sediment into
waterbodies. In sum, sediment quality
in the stream represents the net result
of erosion processes in the watershed.
The lateral view of sediment is dis-
cussed in more detail in Section 2.B.
It is worth noting, however, that from
a water quality perspective, interest may
focus on specific fractions of the sedi-
ment load. For instance, controlling
fine sediment load is often of particular
concern for restoration of habitat for
salmonid fish.
Restoration efforts may be useful for
controlling loads of sediment and sedi-
ment-associated pollutants from the
watershed to streams. These may range
from efforts to reduce upland erosion
to treatments that reduce sediment de-
livery through the riparian zone. Design
of restoration treatments is covered in
Chapter 8.
Figure 2.18: Stream sedimentation. Although
sediment and its transport occur naturally,
changes in sediment load and particle size
have negative impacts.
Physical and Chemical Characteristics
2-27
-------
Preview Sec-
tion D for
more detail on
the effects of
cover on water
temperature.
Sediment Along the Stream Corridor
The longitudinal processes affecting
sediment transport from a water quality
perspective are the same as those dis-
cussed from a geomorphic perspective
in Section 2.B. As in the lateral perspec-
tive, interest from a water quality point
of view may be focused on specific sedi-
ment size fractions, particularly the fine
sediment fraction, because of its effect
on water quality, water temperature,
habitat, and biota.
Water Temperature
Water temperature is a crucial factor in
stream corridor restoration for a number
of reasons. First, dissolved oxygen solu-
bility decreases with increasing water
temperature, so the stress imposed by
oxygen-demanding waste increases with
higher temperatures. Second, tempera-
ture governs many biochemical and
physiological processes in cold-blooded
aquatic organisms, and increased tem-
peratures can increase metabolic and
reproductive rates throughout the food
chain. Third, many aquatic species can
tolerate only a limited range of tempera-
tures, and shifting the maximum and
minimum temperatures within a stream
can have profound effects on species
composition. Finally, temperature also
affects many abiotic chemical processes,
such as reaeration rate, sorption of or-
ganic chemicals to paniculate matter,
and volatilization rates. Temperature in-
creases can lead to increased stress from
toxic compounds, for which the dis-
solved fraction is usually the most
bioactive fraction.
Water Temperature Across the
Stream Corridor
Water temperature within a stream
reach is affected by the temperature of
water upstream, processes within the
stream reach, and the temperature of
influent water. The lateral view ad-
dresses the effects of the temperature of
influent water.
The most important factor for tempera-
ture of influent water within a stream
reach is the balance between water ar-
riving via surface and ground water
pathways. Water that flows over the
land surface to a stream has the oppor-
tunity to gain heat through contact with
surfaces heated by the sun. In contrast,
ground water is usually cooler in sum-
mer and tends to reflect average annual
temperatures in the watershed. Water
flow via shallow ground water pathways
may lie between the average annual
temperature and ambient temperatures
during runoff events.
Both the fraction of runoff arriving via
surface pathways and the temperature
of surface runoff are strongly affected
by the amount of impervious surfaces
within a watershed. For example, hot
paved surfaces in a watershed can heat
surface runoff and significantly increase
the temperature of streams that receive
the runoff.
Water Temperature Along the
Stream Corridor
Water also is subject to thermal loading
through direct effects of sunlight on
streams. For the purposes of restoration,
land use practices that remove overhead
cover or that decrease baseflows can in-
crease instream temperatures to levels
that exceed critical thermal maxima for
fishes (Feminella and Matthews 1984).
Maintaining or restoring normal tem-
perature ranges can therefore be an im-
portant goal for restoration.
Chemical Constituents
Previous chapters have discussed the
physical journey of water as it moves
through the hydrologic cycle. Rain per-
colates to the ground water table or be-
comes overland flow, streams collect
this water and route it toward the
2-28
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
ocean, and evapotranspiration occurs
throughout the cycle. As water makes
this journey, its chemistry changes.
While in the air, water equilibrates with
atmospheric gases. In shallow soils, it
undergoes chemical exchanges with in-
organic and organic matter and with
soil gases. In ground water, where transit
times are longer, there are more oppor-
tunities for minerals to dissolve. Similar
chemical reactions continue along
stream corridors. Everywhere, water in-
teracts with everything it touchesair,
rocks, bacteria, plants, and fishand is
affected by human disturbances.
Scientists have been able to define sev-
eral interdependent cycles for many of
the common dissolved constituents in
water. Central among these cycles is the
behavior of oxygen, carbon, and nutri-
ents, such as nitrogen (N), phosphorus
(P), sulfur (S), and smaller amounts of
common trace elements.
Iron, for example, is an essential ele-
ment in the metabolism of animals and
plants. Iron in aquatic systems may be
present in one of two oxidation states.
Ferric iron (Fe3+) is the more oxidized
form and is very sparingly soluble in
water. The reduced form, ferrous iron
(Fe2+), is more soluble by many orders
of magnitude. In many aquatic systems,
such as lakes for example, iron can cycle
from the ferric state to the ferrous state
and back again (Figure 2.19). The oxi-
dation of ferrous iron followed by the
precipitation of ferric iron results in
iron coatings on the surfaces of some
stream sediments. These coatings, along
with organic coatings, play a substantial
role in the aquatic chemistry of toxic
trace elements and toxic organic chemi-
cals. The chemistry of toxic organic
chemicals and metals, along with the
cycling and chemistry of oxygen, nitro-
gen, and phosphorus, will be covered
later in this section.
Clay
Sand
organic coating
iron coating
Figure 2.19: The organic coatings on suspend-
ed sediment from streams. Water chemistry
determines whether sediment will carry
adsorbed materials or if stream sediments
will be coated.
The total concentration of all dissolved
ions in water, also known as salinity,
varies widely. Precipitation typically
contains only a few parts per thousand
(ppt) of dissolved solids, while the
salinity of seawater averages about 35
ppt (Table 2.5). The concentration of
dissolved solids in freshwater may vary
from only 10 to 20 mg/L in a pristine
mountain stream to several hundred
mg/L in many rivers. Concentrations
may exceed 1,000 mg/L in arid water-
sheds. A dissolved solids concentration
of less than 500 mg/L is recommended
for public drinking water, but this
threshold is exceeded in many areas of
the country. Some crops (notably fruit
trees and beans) are sensitive to even
modest salinity, while other crops, such
as cotton, barley, and beets, tolerate
high concentrations of dissolved solids.
Agricultural return water from irrigation
may increase salinity in streams, partic-
ularly in the west. Recommended salin-
ity limits for livestock vary from 2,860
mg/L for poultry to 12,900 mg/L for
adult sheep. Plants, fish, and other
aquatic life also vary widely in their
adaptation to different concentrations
of dissolved solids. Most species have a
maximum salinity tolerance, and few
can live in very pure water of very low
ionic concentration.
Physical and Chemical Characteristics
2-29
-------
Table 2.5:
Composition, in mil-
ligrams per liter, of
rain and snow.
1 Samples 1
Constituent
Si02
Al
Fe
Ca
Mg
Na
K
NH4
HCO3
S04
Cl
N02
NO3
Total
dissolved
solids
pH
rn
0.0
.01
.00
.0
.2
.6
.6
.0
3
1.6
.2
.02
.1
4.8
5.6
OB
1.2
.65 1.2
.14 .7
.56 .0
.11 .0
j-y-j
2.18 .7
.57 .8
.00
.62 .2
8.2
6.4
KB
0.3
.8
1.2
9.4
.0
4
7.6
17
.02
.0
38
5.5
an
0.1
.015
1.41 .075
.027
.42 .220
.072
2.14 1.1
.22
4.9
1. Snow, Spooner Summit. U.S. Highway 50, Nevada (east of Lake
Tahoe) (Feth, Rogers, and Roberson, 1964).
2. Average composition of rain, August 1962 to July 1963, at 27 points
in North Carolina and Virginia (Gambell and Fisher, 1966).
3. Rain, Menlo Park, Calif., 7:00 p.m. Jan. 9 to 8:00 a.m. Jan 10, 1958
(Whitehead and Feth, 1964).
4. Rain, Menlo Park, Calif., 8:00 a.m. to 2:00 p.m. Jan 10, 1958
(Whitehead and Feth, 1964).
5. Average for inland sampling stations in the United States for 1 year.
Data from Junge and Werby (1958), as reported by Whitehead and
Feth (1964).
6. Average composition of precipitation, Williamson Creek, Snohomish
County, Wash., 1973-75. Also reported: As, 0.00045 mg/L; Cu 0.0025
mg/L; Pb, 0.0033 mg/L; Zn, 0.0036 mg/L (Deithier, D.P., 1977, Ph.D.
thesis. University of Washington, Seattle).
pH, Alkalinity, and Acidity
Alkalinity, acidity, and buffering capac-
ity are important characteristics of water
that affect its suitability for biota and
influence chemical reactions. The acidic
or basic (alkaline) nature of water is
commonly quantified by the negative
logarithm of the hydrogen ion concen-
tration, or pH. A pH value of 7 repre-
sents a neutral condition; a pH value
less than 5 indicates moderately acidic
conditions; a pH value greater than 9
indicates moderately alkaline condi-
tions. Many biological processes, such
as reproduction, cannot function in
acidic or alkaline waters. In particular,
aquatic organisms may suffer an os-
motic imbalance under sustained expo-
sure to low pH waters. Rapid
fluctuations in pH also can stress
aquatic organisms. Finally, acidic condi-
tions also can aggravate toxic contami-
nation problems through increased
solubility, leading to the release of toxic
chemicals stored in stream sediments.
pH, Alkalinity, and Acidity Across the
Stream Corridor
The pH of runoff reflects the chemical
characteristics of precipitation and the
land surface. Except in areas with signif-
icant ocean spray, the dominant ion in
most precipitation is bicarbonate
(HCO,-). The bicarbonate ion is pro-
duced by carbon dioxide reacting with
water:
H2O + CO2 = H+ + HCO,"
This reaction also produces a hydrogen
ion (H+), thus increasing the hydrogen
ion concentration and acidity and low-
ering the pH. Because of the presence
of CO2 in the atmosphere, most rain is
naturally slightly acidic, with a pH of
about 5.6. Increased acidity in rainfall
can be caused by inputs, particularly
from burning fossil fuels.
As water moves through soils and rocks,
its pH may increase or decrease as addi-
tional chemical reactions occur. The car-
bonate buffering system controls the
acidity of most waters. Carbonate
buffering results from chemical equilib-
rium between calcium, carbonate, bicar-
bonate, carbon dioxide, and hydrogen
ions in the water and carbon dioxide in
the atmosphere. Buffering causes waters
to resist changes in pH (Wetzel 1975).
Alkalinity refers to the acid-neutralizing
capacity of water and usually refers to
those compounds that shift the pH in
an alkaline direction (APHA 1995, Wet-
zel 1975). The amount of buffering is
related to the alkalinity and primarily
determined by carbonate and bicarbon-
ate concentration, which are introduced
into the water from dissolved calcium
carbonate (i.e., limestone) and similar
2-30
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
minerals present in the watershed. For
example, when water interacts with
limestone, the following dissolution
reaction occurs:
H+ + CaCO, = Ca2+ + HCCT
This reaction consumes hydrogen ions,
thus raising the pH of the water. Con-
versely, runoff may acidify when all al-
kalinity in the water is consumed by
acids, a process often attributed to the
input of strong mineral acids, such as
sulfuric acid, from acid mine drainage,
and weak organic acids, such as humic
and fulvic acids, which are naturally
produced in large quantities in some
types of soils, such as those associated
with coniferous forests, bogs, and wet-
lands. In some streams, pH levels can
be increased by restoring degraded wet-
lands that intercept acid inputs, such as
acid mine drainage, and help neutralize
acidity by converting sulfates from sul-
furic acid to insoluble nonacidic metal
sulfides that remain trapped in wetland
sediments.
pH, Alkalinity, and Acidity Along the
Stream Corridor
Within a stream, similar reactions occur
between acids in the water, atmospheric
CO,, alkalinity in the water column, and
streambed material. An additional char-
acteristic of pH in some poorly buffered
waters is high daily variability in pH lev-
els attributable to biological processes
that affect the carbonate buffering sys-
tem. In waters with large standing crops
of aquatic plants, uptake of carbon diox-
ide by plants during photosynthesis re-
moves carbonic acid from the water,
which can increase pH by several units.
Conversely, pH levels may fall by several
units during the night when photosyn-
thesis does not occur and plants give off
carbon dioxide. Restoration techniques
that decrease instream plant growth
through increased shading or reduction
in nutrient loads or that increase reaera-
tion also tend to stabilize highly vari-
able pH levels attributable to high rates
of photosynthesis.
The pH within streams can have impor-
tant consequences for toxic materials.
High acidity or high alkalinity tend to
convert insoluble metal sulfides to solu-
ble forms and can increase the concen-
tration of toxic metals. Conversely, high
pH can promote ammonia toxicity. Am-
monia is present in water in two forms,
unionized (NHJ and ionized (NH4+).
Of these two forms of ammonia, un-
ionized ammonia is relatively highly
toxic to aquatic life, while ionized am-
monia is relatively negligibly toxic. The
proportion of un-ionized ammonia is
determined by the pH and temperature
of the water (Bowie et al. 1985)as pH
or temperature increases, the propor-
tion of un-ionized ammonia and the
toxicity also increase. For example, with
a pH of 7 and a temperature of 68 ° F,
only about 0.4 percent of the total am-
monia is in the un-ionized form, while
at a pH of 8.5 and a temperature of
78 °F, 15 percent of the total ammonia
is in the un-ionized form, representing
35 times greater potential toxicity to
aquatic life.
Dissolved Oxygen
Dissolved oxygen (DO) is a basic re-
quirement for a healthy aquatic ecosys-
tem. Most fish and aquatic insects
"breathe" oxygen dissolved in the water
column. Some fish and aquatic organ-
isms, such as carp and sludge worms,
are adapted to low oxygen conditions,
but most sport fish species, such as
trout and salmon, suffer if DO concen-
trations fall below a concentration of 3
to 4 mg/L. Larvae and juvenile fish are
more sensitive and require even higher
concentrations of DO (USEPA 1997).
Many fish and other aquatic organisms
can recover from short periods of low
Physical and Chemical Characteristics
2-31
-------
FAST
FORWARD
Preview Section
D for more in-
formation on
DO.
DO in the water. However, prolonged
episodes of depressed dissolved oxygen
concentrations of 2 mg/L or less can re-
sult in "dead" waterbodies. Prolonged
exposure to low DO conditions can suf-
focate adult fish or reduce their repro-
ductive survival by suffocating sensitive
eggs and larvae, or can starve fish by
killing aquatic insect larvae and other
prey. Low DO concentrations also favor
anaerobic bacteria that produce the
noxious gases or foul odors often asso-
ciated with polluted waterbodies.
Water absorbs oxygen directly from the
atmosphere, and from plants as a result
of photosynthesis. The ability of water
to hold oxygen is influenced by temper-
ature and salinity. Water loses oxygen
primarily by respiration of aquatic
plants, animals, and microorganisms.
Due to their shallow depth, large sur-
face exposure to air, and constant mo-
tion, undisturbed streams generally
contain an abundant DO supply. How-
ever, external loads of oxygen-demand-
ing wastes or excessive plant growth
induced by nutrient loading followed
by death and decomposition of vegeta-
tive material can deplete oxygen.
Dissolved Oxygen Across the
Stream Corridor
Oxygen concentrations in the water col-
umn fluctuate under natural conditions,
but oxygen can be severely depleted as
a result of human activities that intro-
duce large quantities of biodegradable
organic materials into surface waters.
Excess loading of nutrients also can de-
plete oxygen when plants within a
stream produce large quantities of plant
biomass.
Loads of oxygen-demanding waste usu-
ally are reported as biochemical oxygen
demand (BOD). BOD is a measure of
the amount of oxygen required to oxi-
dize organic material in water by bio-
logical activity. As such, BOD is an
equivalent indicator rather than a true
physical or chemical substance. It mea-
sures the total concentration of DO that
eventually would be demanded as
wastewater degrades in a stream.
BOD also is often separated into car-
bonaceous and nitrogenous compo-
nents. This is because the two fractions
tend to degrade at different rates. Many
water quality models for dissolved oxy-
gen require as input estimates of ulti-
mate carbonaceous BOD (CBODJ and
either ultimate nitrogenous BOD
(NBODJ or concentrations of individ-
ual nitrogen species.
Oxygen-demanding wastes can be
loaded to streams by point source dis-
charges, nonpoint loading, and ground
water. BOD loads from major point
sources typically are controlled and
monitored and thus are relatively easy
to analyze. Nonpoint source loads of
BOD are much more difficult to ana-
lyze. In general, any loading of organic
material from a watershed to a stream
results in an oxygen demand. Excess
loads of organic material may arise
from a variety of land use practices,
coupled with storm events, erosion,
and washoff. Some agricultural activi-
ties, particularly large-scale animal
operations and improper manure appli-
cation, can result in significant BOD
loads. Land-disturbing activities of silvi-
culture and construction can result in
high organic loads through the erosion
of organic topsoil. Finally, urban runoff
often is loaded with high concentra-
tions of organic materials derived from
a variety of sources.
Dissolved Oxygen Along the
Stream Corridor
Within a stream, DO content is affected
by reaeration from the atmosphere, pro-
duction of DO by aquatic plants as a
by-product of photosynthesis, and con-
sumption of DO in respiration by
2-32
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
plants, animals, and, most importantly,
microorganisms.
Major processes affecting the DO bal-
ance within a stream are summarized in
Figure 2.20. This includes the following
components:
Carbonaceous deoxygenation
Nitrogenous deoxygenation
(nitrification)
Reaeration
Sediment oxygen demand
Photosynthesis and respiration
of plants.
Reaeration is the primary route for in-
troducing oxygen into most waters.
Oxygen gas (OJ constitutes about 21
percent of the atmosphere and readily
dissolves in water. The saturation con-
centration of DO in water is a measure
of the maximum amount of oxygen
that water can hold at a given tempera-
ture. When oxygen exceeds the satura-
tion concentration, it tends to degas to
the atmosphere. When oxygen is below
the saturation concentration, it tends to
diffuse from the atmosphere to water.
The saturation concentration of oxygen
decreases with temperature according to
a complex power function equation
(APHA 1995). In addition to tempera-
ture, the saturation concentration is af-
fected by water salinity and the
atmospheric pressure. As the salinity of
water increases, the saturation concen-
tration decreases. As the atmospheric
pressure increases the saturation con-
centration also increases.
Interactions between atmospheric and
DO are driven by the partial pressure
gradient in the gas phase and the con-
centration gradient in the liquid phase
(Thomann and Mueller 1987). Turbu-
lence and mixing in either phase de-
crease these gradients and increase
reaeration, while a quiescent, stagnant
surface or films on the surface reduce
reaeration. In general, oxygen transfer
in natural waters depends on the fol-
lowing:
Internal mixing and turbulence due
to velocity gradients and fluctuation
Temperature
Wind mixing
Waterfalls, dams, and rapids
Surface films
Water column depth.
Figure 2.20: Interrelationship of major kinetic
processes for BOD and DO as represented by
water quality models. Complex, interacting
physical and chemical processes can sometimes
be simplified by models in order to plan a
restoration.
tffc
atmospheric
oxygen
carbonaceous
deoxygenation
Physical and Chemical Characteristics
2-33
-------
Stream restoration techniques often
take advantage of these relationships,
for instance by the installation of artifi-
cial cascades to increase reaeration.
Many empirical formulations have been
developed for estimating stream reaera-
tion rate coefficients; a detailed sum-
mary is provided in Bowie et al. (1985).
In addition to reaeration, oxygen is pro-
duced instream by aquatic plants.
Through photosynthesis, plants capture
energy from the sun to fix carbon diox-
ide into reduced organic matter:
6 CO +6HO = CH O +6O
2. 2 6 12 6 2
Note that photosynthesis also produces
oxygen. Plants utilize their simple pho-
tosynthetic sugars and other nutrients
(notably nitrogen [N], phosphorus [P],
and sulfur [S] with smaller amounts of
several common and trace elements) to
operate their metabolism and to build
their structures.
Most animal life depends on the release
of energy stored by plants in the photo-
synthetic process. In a reaction that is
the reverse of photosynthesis, animals
consume plant material or other ani-
mals and oxidize the sugars, starches,
and proteins to fuel their metabolism
and build their own structure. This
process is known as respiration and
consumes dissolved oxygen. The actual
process of respiration involves a series
of energy converting oxidation-reduc-
tion reactions. Higher animals and
many microorganisms depend on suffi-
cient dissolved oxygen as the terminal
electron acceptor in these reactions and
cannot survive without it. Some mi-
croorganisms are able to use other com-
pounds (such as nitrate and sulfate) as
electron acceptors in metabolism and
can survive in anaerobic (oxygen-
depleted) environments.
Detailed information on analysis and
modeling of DO and BOD in streams
is contained in a number of references
(e.g., Thomann and Mueller 1987), and
a variety of well-tested computer mod-
els are available. Most stream water
quality models account for CBOD in
the water column separately from
NBOD (which is usually represented
via direct mass balance of nitrogen
species) and sediment oxygen demand or
SOD. SOD represents the oxygen de-
mand of sediment organism respiration
and the benthic decomposition of or-
ganic material. The demand of oxygen
by sediment and benthic organisms
can, in some instances, be a significant
fraction of the total oxygen demand in
a stream. This is particularly true in
small streams. The effects may be par-
ticularly acute during low-flow and
high-temperature conditions, as micro-
bial activity tends to increase with in-
creased temperature.
The presence of toxic pollutants in the
water column can indirectly lower oxy-
gen concentrations by killing algae,
aquatic weeds, or fish, which provide
an abundance of food for oxygen-
consuming bacteria. Oxygen depletion
also can result from chemical reactions
that do not involve bacteria. Some pol-
lutants trigger chemical reactions that
place a chemical oxygen demand on
receiving waters.
Nutrients
In addition to carbon dioxide and
water, aquatic plants (both algae and
higher plants) require a variety of other
elements to support their bodily struc-
tures and metabolism. Just as with ter-
restrial plants, the most important of
these elements are nitrogen and phos-
phorus. Additional nutrients, such as
potassium, iron, selenium, and silica,
are needed in smaller amounts and
generally are not limiting factors to
plant growth. When these chemicals are
limited, plant growth may be limited.
This is an important consideration in
2-34
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
stream management. Plant biomass
(either created instream or loaded from
the watershed) is necessary to support
the food chain. However, excessive
growth of algae and other aquatic
plants instream can result in nuisance
conditions, and the depletion of dis-
solved oxygen during nonphotosyn-
thetic periods by the respiration of
plants and decay of dead plant material
can create conditions unfavorable to
aquatic life.
Phosphorus in freshwater systems exists
in either a paniculate phase or a dis-
solved phase. Both phases include or-
ganic and inorganic fractions. The
organic particulate phase includes living
and dead particulate matter, such as
plankton and detritus. Inorganic partic-
ulate phosphorus includes phosphorus
precipitates and phosphorus adsorbed
to particulates. Dissolved organic phos-
phorus includes organic phosphorus
excreted by organisms and colloidal
phosphorus compounds. The soluble
inorganic phosphate forms H2PO4~,
HPO42, and PO43, collectively known
as soluble reactive phosphorus (SRP) are
readily available to plants. Some con-
densed phosphate forms, such as those
found in detergents, are inorganic but
are not directly available for plant up-
take. Aquatic plants require nitrogen
and phosphorus in different amounts.
For phytoplankton, as an example, cells
contain approximately 0.5 to 2.0 jag
phosphorus per ug chlorophyll, and 7
to 10 jig nitrogen per ug chlorophyll.
From this relationship, it is clear that
the ratio of nitrogen and phosphorus
required is in the range of 5 to 20
(depending on the characteristics of
individual species) to support full
utilization of available nutrients and
maximize plant growth. When the
ratio deviates from this range, plants
cannot use the nutrient present in ex-
cess amounts. The other nutrient is then
said to be the limiting nutrient on plant
growth. In streams experiencing exces-
sive nutrient loading, resource man-
agers often seek to control loading of
the limiting nutrient at levels that pre-
vent nuisance conditions.
In the aquatic environment, nitrogen
can exist in several formsdissolved ni-
trogen gas (NJ, ammonia and ammo-
nium ion (NH3 and NH4+), nitrite
(NO2), nitrate (NO3~), and organic ni-
trogen as proteinaceous matter or in
dissolved or particulate phases. The
most important forms of nitrogen in
terms of their immediate impacts on
water quality are the readily available
ammonia ions, nitrites, and nitrates. Be-
cause they must be converted to a form
more usable by plants, particulate and
organic nitrogen are less important in
the short term.
It may seem unusual that nitrogen
could limit plant growth, given that the
atmosphere is about 79 percent nitro-
gen gas. However, only a few life-forms
(for example, certain bacteria and blue-
green algae) have the ability to fix nitro-
gen gas from the atmosphere. Most
plants can use nitrogen only if it is
available as ammonia (NH3, commonly
present in water as the ionic form am-
monium, NH4+) or as nitrate (NO3~)
(Figure 2.21). However, in freshwater
systems, growth of aquatic plants is
more commonly limited by phospho-
rus than by nitrogen. This limitation oc-
curs because phosphate (PO43 ) forms
insoluble complexes with common
constituents in water (Ca++ and variable
amounts of OH", Cl~, and F ). Phospho-
rus also sorbs to iron coatings on clay
and other sediment surfaces and is
therefore removed from the water col-
umn by chemical processes, resulting in
the reduced ability of the water body to
support plant growth.
Physical and Chemical Characteristics
2-35
-------
riparian
vegetation
biota
cyanobacteria
benthic algae
decomposition
excretion
participate
organic matter
and associated decomposition
microbes accum-
excretion ulation
ground water dissolved organic nitrogen NC>3
Figure 2.21: Dynamics and transformations of nitrogen in a stream ecosystem. Nutrient cycling
from one form to another occurs with changes in nutrient inputs, as well as temperature and
oxygen available.
Nutrients Across the Stream Corridor
Both nitrogen and phosphorus are
delivered to surface waters at an ele-
vated rate as a result of human activi-
ties, including point source discharges
of treated wastewater and nonpoint
sources, such as agriculture and urban
development. In many developed wa-
tersheds, a major source of nutrients
is the direct discharge of treated waste
from wastewater treatment plants, as
well as combined sewer overflows
(CSOs). Such point source discharges
are regulated under the National Pollu-
tant Discharge Elimination System
(NPDES) and usually are well character-
ized by monitoring. The NPDES re-
quires permitted dischargers to meet
2-36
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
both numeric and narrative water qual-
ity standards in streams. While most
states do not have numeric standards
for nutrients, point source discharges
of nutrients are recognized as a factor
leading to stream degradation and fail-
ure to achieve narrative water quality
standards. As a result, increasingly strin-
gent limitations on nutrient concentra-
tions in wastewater treatment plant
effluent (particularly phosphorus) have
been imposed in many areas.
In many cases the NPDES program has
significantly cleaned up rivers and
streams; however, many streams still do
not meet water quality standards, even
with increasingly stringent regulatory
standards. Scientists and regulators now
understand that the dominant source of
nutrients in many streams is from non-
point sources within the stream's water-
shed, not from point sources such as
wastewater treatment plants. Typical
land uses that contribute to the non-
point contamination of streams are the
application of fertilizers to agricultural
fields and suburban lawns, the improper
handling of animal wastes from live-
stock operations, and the disposal of
human waste in septic systems. Storm
runoff from agricultural fields can con-
tribute nutrients to a stream in dissolved
forms as well as paniculate forms.
Because of its tendency to sorb to sedi-
ment particles and organic matter,
phosphorus is transported primarily in
surface runoff with eroded sediments.
Inorganic nitrogen, on the other hand,
does not sorb strongly and can be trans-
ported in both paniculate and dissolved
phases in surface runoff. Dissolved in-
organic nitrogen also can be trans-
ported through the unsaturated zone
(interflow) and ground water to water-
bodies. Table 2.6 presents common
point and nonpoint sources of nitrogen
and phosphorus loading and shows the
approximate concentrations delivered.
Note that nitrates are naturally occur-
ring in some soils.
Nutrients Along the Stream Corridor
Nitrogen, because it does not sorb
strongly to sediment, moves easily be-
tween the substrate and the water col-
umn and cycles continuously. Aquatic
organisms incorporate dissolved and
paniculate inorganic nitrogen into pro-
teinaceous matter. Dead organisms de-
compose and nitrogen is released as
ammonia ions and then converted to
nitrite and nitrate, where the process
begins again.
Phosphorus undergoes continuous
transformations in a freshwater envi-
ronment. Some phosphorus will sorb to
Table 2.6: Sources and concentrations of pollutants from common point and nonpoint sources.
Source
Urban runoff3
Livestock operations3
Atmosphere (wet deposition)3
90% forest^
50% forestd
90% agriculture"1
Untreated wastewater3
Treated wastewater3-6
1 Total Nitrogen (mg/L)
3-10
6-80Qb
0.9
0.06-0.19
0.18-0.34
0.77-5.04
35
30
1 Total Phosphorus (mg/L)
0.2-1.7
4-5
0.01 5C
0.006-0.012
0.013-0.015
0.085-0.104
10
10
a Novotny and Olem (1994).
b As organic nitrogen.
c Sorbed to airborne particulate.
d Omernik (1987).
e With secondary treatment.
Physical and Chemical Characteristics
2-37
-------
sediments in the water column or sub-
strate and be removed from circulation.
The SRP (usually as orthophosphate) is
assimilated by aquatic plants and con-
verted to organic phosphorus. Aquatic
plants then may be consumed by detri-
tivores and grazers, which in turn ex-
crete some of the organic phosphorus
as SRP. Continuing the cycle, the SRP is
rapidly assimilated by aquatic plants.
Toxic Organic Chemicals
Pollutants that cause toxicity in animals
or humans are of obvious concern to
restoration efforts. Toxic organic chemi-
cals (TOC) are synthetic compounds
that contain carbon, such as polychlori-
nated biphenyls (PCBs) and most pesti-
cides and herbicides. Many of these
synthesized compounds tend to persist
and accumulate in the environment be-
cause they do not readily break down
in natural ecosystems. Some of the
most toxic synthetic organics, DDT and
PCBs, have been banned from use in
the United States for decades yet con-
tinue to cause problems in the aquatic
ecosystems of many streams.
Toxic Organic Chemicals Across the
Stream Corridor
TOCs may reach a water body via both
point and nonpoint sources. Because
permitted NPDES point sources must
meet water quality standards instream
and because of whole effluent toxicity
requirements, continuing TOC prob-
lems in most streams are due to non-
point loading, recycling of materials
stored in stream and riparian sedi-
ments, illegal dumping, or accidental
spills. Two important sources of non-
point loading of organic chemicals are
application of pesticides and herbicides
in connection with agriculture, silvicul-
ture, or suburban lawn care, and runoff
from potentially polluted urban and in-
dustrial land uses.
The movement of organic chemicals
from the watershed land surface to a
water body is largely determined by the
characteristics of the chemical, as dis-
cussed below under the longitudinal
perspective. Pollutants that tend to sorb
strongly to soil particles are primarily
transported with eroded sediment. Con-
trolling sediment delivery from source
area land uses is therefore an effective
management strategy. Organic chemi-
cals with significant solubility may be
transported directly with the flow of
water, particularly stormflow from im-
pervious urban surfaces.
Toxic Organic Chemicals Along the
Stream Corridor
Among all the elements of the earth,
carbon is unique in its ability to form a
virtually infinite array of stable covalent
bonds with itself: long chains, branches
and rings, spiral helixes. Carbon mole-
cules can be so complex that they are
able to encode information for the orga-
nization of other carbon structures and
the regulation of chemical reactions.
The chemical industry has exploited
this to produce many useful organic
chemicals: plastics, paints and dyes,
fuels, pesticides, pharmaceuticals, and
other items of modern life. These prod-
ucts and their associated wastes and by-
products can interfere with the health
of aquatic ecosystems. Understanding
the transport and fate of synthetic or-
ganic compounds (SOC) in aquatic envi-
ronments continues to challenge
scientists. Only a general overview of
the processes that govern the behavior
of these chemicals along stream corri-
dors is presented here.
Solubility
It is the nature of the carbon-carbon
bond that electrons are distributed rela-
tively uniformly between the bonded
atoms. Thus a chained or ringed hydro-
carbon is a fairly nonpolar compound.
2-38
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
This nonpolar nature is dissimilar to
the molecular structure of water, which
is a very polar solvent.
On the general principle that "like dis-
solves like," dissolved constituents in
water tend to be polar. Witness, for ex-
ample, the ionic nature of virtually all
inorganic constituents discussed thus
far in this chapter. How does an organic
compound become dissolved in water?
There are several ways. The compound
can be relatively small, so it minimizes
its disturbance of the polar order of
things in aqueous solution. Alterna-
tively, the compound may become
more polar by adding polar functional
groups (Figure 2.22). Alcohols are or-
ganic compounds with -OH groups at-
tached; organic acids are organic
compounds with attached -COOH
groups. These functional groups are
highly polar and increase the solubility
of any organic compound. Even more
solubility in water is gained by ionic
functional groups, such as -COO .
Another way that solubility is enhanced
is by increased aromaticity. Aromaticity
refers to the delocalized bonding struc-
ture of a ringed compound like ben-
zene (Figure 2.23). (Indeed, all
aromatic compounds can be considered
derivatives of benzene.) Because elec-
trons are free to "dance around the
ring" of the benzene molecule, benzene
and its derivatives are more compatible
with the polar nature of water.
A simple example will illustrate the
factors enhancing aqueous solubility of
organic compounds. Six compounds,
each having six carbons, are shown in
Table 2.7. Hexane is a simple hydrocar-
bon, an alkane whose solubility is 10
mg/L. Simply by adding a single -OH
group, which converts hexane to the al-
cohol hexanol, solubility is increased to
5,900 mg/L. You can bend hexane into
a ringed alkane structure called cyclo-
hexane. Forming the ring makes cyclo-
hexane smaller than hexane and
increases its solubility, but only to 55
mg/L. Making the ring aromatic by
forming the six-carbon benzene mole-
cule increases solubility all the way to
1,780 mg/L. Adding an -OH to benzene
to form a phenol leads to another dra-
Figure 2.22: Relative aqueous solubility of different functional groups. The solubility of a
contaminant in water largely determines the extent to which it will impact water quality.
ether
C-O-C
ester
carbonyl
carboxyl
hydroxyl
amine
carboxylate
C-O-R
P
-c'-OH
-OH
-NH2
I
I
I
I
10 100 1,000
Relative Aqueous Solubility
10,000
Physical and Chemical Characteristics
2-39
-------
H
I
H
I
H-C
I
H-C
C-H
II
C-H
HC
H C
C-H
C-H
I
H
I
H
Figure 2.23: Aromatic hydrocarbons. Benzene
is soluble in water because of its "aromatic"
structure.
matic increase in solubility (to 82,000
mg/L). Adding a chloride atom to the
benzene ring diminishes its aromatic
character (chloride inhibits the dancing
electrons), and thus the solubility of
chlorobenzene (448 mg/L) is less than
benzene.
Sorption
In the 1940s, a young pharmaceutical
industry sought to develop medicines
that could be transported in digestive
fluids and blood (both of which are
essentially aqueous solutions) and
could also diffuse across cell mem-
branes (which have, in part, a rather
nonpolar character). The industry devel-
oped a parameter to quantify the polar
versus nonpolar character of potential
drugs, and they called that parameter
the octanol-water partition coefficient.
Basically they put water and octanol
(an eight-carbon alcohol) into a vessel,
added the organic compound of inter-
est, and shook the combination up.
After a period of rest, the water and oc-
Table 2.7: Solubility of six-carbon compounds.
| Compound
Hexane
Hexanol
Cyclohexane
Benzene
Phenol
Chlorobenzene
| Solubility
10 mg/L
5,900 mg/L
55 mg/L
1,780 mg/L
82,000 mg/L
448 mg/L
tanol separate (neither is very soluble in
the other), and the concentration of the
organic compound can be measured in
each phase. The octanol-water partition
coefficient, or Kow, is defined simply as:
K = concentration in octanol /
ow '
concentration in water
The relation between water solubility
and K is shown in Figure 2.24. Gener-
ow *-*
ally we see that very insoluble com-
pounds like DDT and PCBs have very
high values of Kow. Alternatively, organic
acids and small organic solvents like
TCE are relatively soluble and have low
K values.
ow
The octanol-water partition coefficient
has been determined for many com-
pounds and can be useful in under-
standing the distribution of SOC
between water and biota, and between
water and sediments. Compounds with
high K tend to accumulate in fish
ow
tissue (Figure 2.25). The sediment-water
distribution coefficient, often expressed
as Kd, is defined in a sediment-water
mixture at equilibrium as the ratio of
the concentration in the sediment to
the concentration in the water:
K. = concentration in sediment /
d
concentration in water
One might ask whether this coefficient
is constant for a given SOC. Values of Kd
for two polyaromatic hydrocarbons in
various soils are shown in Figure 2.26.
For pyrene (which consists of four ben-
zene rings stuck together), the Kd ratios
vary from about 300 to 1500. For
phenanthrene (which consists of three
benzene rings stuck together), Kd varies
from about 10 to 300. Clearly Kd is not a
constant value for either compound.
But, Kd does appear to bear a relation to
the fraction of organic carbon in the var-
ious sediments. What appears to be con-
stant is not Kd itself, but the ratio of Kd
to the fraction of organic carbon in the
sediment. This ratio is referred to as K :
2-40
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
0)
01
5
O
"4-*
'5
£
107
106
105
io4
5 io3
102
DDT
0 2,4,5,2',4',5' - PCB
leptophos
- 0 2,4,5,2',5' -PCB
DDE
04,4' - PCB
dichlofenthion
chlorpyrifos
ronnel
dialifor methyl chlorpyrifos
phosatone 0 diphenyl ether
parathion
dicapthon^ naphthalene
fenitrothion
p-dichlorobenzene
iodobenzene
bromobenzene
Jichlorobenzene
phosmel 2,4-D jP toluene
carbon tetrachlonde
tetrachloroethylene «salicylic acid
benzene
flourobenzene^^ chloroform
nitrobenzene benzoic acid
phenylacetic acid
phenoxyzcetic acid0
TO'
TO'
1 10 102 103
Solubility in Water (umoles/L)
104
105 106
Figure 2.24: Relationship between octanol/H,O partition coefficient and aqueous solubility.
The relative solubility in water is a substance's "Water Partition Coefficient."
5 r
S 4
£3
u
CO
hexachloro-
benzene
biphenyl
p-dichloro-
benzene*
diphenylether
tetrachloroethylene
carbontetrachloride
234567
Log Poet
Figure 2.25: Relationship between octanol/
water partition (Poa) coefficient and bioaccu-
mulation factor (BCF) in trout muscle. Water
quality can be inferred by the accumulation
of contaminants in fish tissue.
0)
c
1800
1500
1200
900
600
300
0
slope = K
600
500
400
300
200
100
c
ro
OJ
Q.
o
0.0 .005 .010 .015 .020
Fraction Organic Carbon
.025
Figure 2.26: Relationship between pyrene,
phenanthrene, and fraction organic carbon.
Contaminant concentrations in sediment vs.
water (KJ are related to the amount of organ-
ic carbon available.
Physical and Chemical Characteristics
2-41
-------
Koc = Kd / fraction of organic carbon
in sediment
Various workers have related Koc to Kow
and to water solubility (Table 2.8).
Using K , K , and K, to describe the
° ow oc d
partitioning of an SOC between water
and sediment has shown some utility,
but this approach is not applicable to
the sorption of all organic molecules in
all systems. Sorption of some SOC
occurs by hydrogen bonding, such as
occurs in cation exchange or metal
sorption to sediments (Figure 2.27).
Sorption is not always reversible; or at
least after sorption occurs, desorption
may be very slow.
Volatilization
Organic compounds partition from
water into air by the process of
volatilization. An air-water distribution
coefficient, the Henry's Law constant
(H), has been defined as the ratio of
the concentration of an SOC in air in
equilibrium with its concentration in
water:
H = SOC concentration in air /
SOC concentration in water
"SOC" = synthetic organic compounds
A Henry's Law constant for an SOC can
be estimated from the ratio of the com-
pound's vapor pressure to its water sol-
ubility. Organic compounds that are
inherently volatile (generally low mole-
cular weight solvents) have very high
Henry's Law constants. But even com-
pounds with very low vapor pressure
can partition into the atmosphere. DDT
and PCBs for example, have modest
Henry's Law constants because their sol-
ubility in water is so low. These SOC
also have high K values and so may be-
Table 2.8: Regression equations for sediment adsorption coefficients (Km) for various
contaminants.
Equation3
log K0<: = -0.55 log S + 3.64 (S in mg/L)
log Koc = -0.54 log S + 0.44
(S in mole fraction)
log Koc = -0.557 log S + 4.277
(S in ji moles/L)d
log Koc = 0.544 log Kow + 1.377
log Koc = 0.937 log Kow- 0.006
log Koc = 1.00 log Kow-0.21
log Koc = 0.95 log Kow + 0.02
log Koc = 1.029 log Kow - 0.18
log Koc = 0.524 log Kom + O.S
log Koc = 0.0067 (p - 45N) + 0.237^
log Koc = 0.681 log 8CF(f) + 1.963
log Koc = 0.681 log 8CF(t) + 1.886
No.b I r2<: I Chemical Classes Represented
0.71 Wide variety, mostly pesticides
106
10
0.94 Mostly aromatic or polynuclear aromatics;
two chlorinated
15 0.99 Chlorinated hydrocarbons
45 0.74 Wide variety, mostly pesticides
19 0.95 Aromatics, polynuclear aromatics, triazines, and
dinitroaniline herbicides
10 1.00
Mostly aromatic or polynuclear aromatics;
two chlorinated
9 e S-triazines and dinitroaniline herbicides
13 0.91 Variety of insecticides, herbicides, and fungicides
30 0.84 Substituted phenylureas and alkyl-N-phenylcarbamates
29 0.69 Aromatic compounds, urea, 1.3.5-triazines,
carbamates, and uracils
13 0.76 Wide variety, mostly pesticides
22 0.83 Wide variety, mostly pesticides
a Koc = soil (°r sediment) adsorption coefficient; S = water solubility; Kow = octanol-water partition coefficient; BCF(f) = bioconcentration factor
from flowing-water tests; BCF(t) = bioconcentration factor from model ecosystems; P = parachor; N = number of sites in molecule which can
participate in the formation of a hydrogen bond.
b No. = number of chemicals used to obtain regression equation.
c r2 = correlation coefficient for regression equation.
d Equation originally given in terms of Kom. The relationship Kom = Koc/1.724 was used to rewrite the equation in terms of Koc.
e Not available.
f Specific chemicals used to obtain regression equation not specified.
2-42
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
come airborne in association with par-
ticulate matter.
Degradation
SOC can be transformed into a variety
of degradation products. These degrada-
tion products may themselves degrade.
Ultimate degradation, or mineraliza-
tion, results in the oxidation of organic
carbon to carbon dioxide. Major trans-
formation processes include photolysis,
hydrolysis, and oxidation-reduction re-
actions. The latter are commonly medi-
ated by biological systems.
Photolysis refers to the destruction of a
compound by the energy of light. The
energy of light varies inversely with its
wavelength (Figure 2.28). Long-wave
light lacks sufficient energy to break
chemical bonds. Short wave light (x-rays
and gamma rays) is very destructive;
fortunately for life on earth, this type of
radiation largely is removed by our
upper atmosphere. Light near the visi-
ble spectrum reaches the earth's surface
and can break many of the bonds com-
mon in SOC. The fate of organic sol-
vents following volatilization is usually
photolysis in the earth's atmosphere.
Photolysis also can be important in the
degradation of SOC in stream water.
Hydrolysis refers to the splitting of an or-
ganic molecule by water. Essentially
water enters a polar location on a mole-
cule and inserts itself, with an H+ going
to one part of the parent molecule and
an OH- going to the other. The two
parts then separate. A group of SOC
called esters are particularly vulnerable
to degradation by hydrolysis. Many es-
ters have been produced as pesticides
or plasticizers.
Oxidation-reduction reactions are what
fuels most metabolism in the bios-
phere. SOC are generally considered as
sources of reduced carbon. In such situ-
ations, what is needed for degradation
is a metabolic system with the appro-
silica
alumina
H-0
H
<02C-C-H/
AIC-O H-0-0
adsorbents^^ ''H O
Organic Bases Organic Acids
Figure 2.27: Two important types of hydrogen
bonding involving natural organic matter and
mineral surfaces. Some contaminants are car-
ried by sediment particles that are sorbed onto
their surfaces by chemical bonding.
Figure 2.28: Energy of electromagnetic radia-
tion compared with some selected bond ener-
gies. Light breaks chemical bonds of some
compounds through photolysis.
Wavelength Kilocalories Dissociation
(nanometers) per Gram Mole Energies for
of Quanta Diatomic Molecules
J Infrared
L_
Visible
Light
Near
Ultraviolet
Middle
Ultraviolet
Far
Ultraviolet
i^'
-800
-600
-500
Ann
*HJU
-350
-300
-250
>nn
-20
-30
-40
-50
- 60 C S -
-70
- 80 C Cl -
- 90
-100 H.CI-
-110
C.F-
-120
-130
-140
-I I
-Br-Br
-CI-CI
-C« N
-C-O
-H.Br
-S-S
-H.H
-o.o
Physical and Chemical Characteristics
2-43
-------
priate enzymes for the oxidation of the
compound. A sufficient supply of other
nutrients and a terminal electron accep-
tor are also required.
The principle of microbial infallibility in-
formally refers to the idea that given
a supply of potential food, microbial
communities will develop the meta-
bolic capability to use that food for
biochemical energy. Not all degrada-
tion reactions, however, involve the
oxidation of SOC. Some of the most
problematic organic contaminants
are chlorinated compounds.
Chlorinated SOC do not exist naturally,
so microbial systems generally are not
adapted for their degradation. Chlorine
is an extremely electronegative element.
The electronegativity of chlorine refers
to its penchant for sucking on electrons.
This tendency explains why chloride ex-
ists as an anion and why an attached
chloride diminishes the solubility of
an aromatic ring. Given this character,
it is difficult for biological systems to
oxidize chlorinated compounds. An
initial step in that degradation, there-
fore, is often reductive dechlorination.
The chlorine is removed by reducing
the compound (i.e., by giving it elec-
trons). After the chlorines are removed,
degradation may proceed along oxida-
tive pathways. The degradation of
chlorinated SOC thus may require a
sequence of reducing and oxidizing
environments, which water may experi-
ence as it moves between stream and
hyporheic zones.
The overall degradation of SOC often
follows complex pathways. Figure 2.29
shows a complex web of metabolic
reaction for a single parent pesticide.
Hydrolysis, reduction, and oxidation
are all involved in the degradation of
SOC, and the distribution and behavior
of degradation products can be ex-
tremely variable in space and time.
Chemical consequences are rarely the
immediate goal of most restoration
actions. Plans that alter chemical
processes and attributes are usually
focused on changing the physical and
biological characteristics that are vital
to the restoration goals.
Toxic Concentrations of
Bioavailable Metals
A variety of naturally occurring metals,
ranging from arsenic to zinc, have been
established to be toxic to various forms
of aquatic life when present in suffi-
cient concentrations. The primary
mechanisms for water column toxicity
of most metals is adsorption at the gill
surface. While some studies indicate
that particulate metals may contribute
to toxicity, perhaps because of factors
such as desorption at the gill surface,
the dissolved metal concentration most
closely approximates the fraction of
metal in the water column that is
bioavailable. Accordingly, current EPA
policy is that dissolved metal concentra-
tions should be used to set and mea-
sure compliance with water quality
standards (40 CFR 22228-22236, May
4, 1995). For most metals, the dissolved
fraction is equivalent to the inorganic
ionic fraction. For certain metals, most
notably mercury, the dissolved fraction
also may include the metal complexed
with organic binding agents (e.g.,
methyl mercury, which can be produced
in sediments by methanogenic bacteria,
is soluble and highly toxic, and can ac-
cumulate through the food chain).
Toxic Concentrations of Bioavailable
Metals Across the Stream Corridor
Unlike synthetic organic compounds,
toxic metals are naturally occurring. In
common with synthetic organics, met-
als may be loaded to waterbodies from
both point and nonpoint sources. Pol-
lutants such as copper, zinc, and lead
2-44
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
are often of concern in effluent from
wastewater treatment plants but are
required under the NPDES program to
meet numeric water quality standards.
Many of the toxic metals are present at
significant concentrations in most soils
but in sorbed nonbioavailable forms.
Sediment often introduces significant
concentrations of metals such as zinc
into waterbodies. It is then a matter of
whether instream conditions promote
bioavailable dissolved forms of the
metal.
Nonpoint sources of metals first reflect
the characteristics of watershed soils. In
addition, many older industrial areas
have soil concentrations of certain met-
als that are elevated due to past indus-
trial practices. Movement of metals from
soil to watershed is largely a function of
the erosion and delivery of sediment.
In certain watersheds, a major source of
metals loading is provided by acid mine
drainage. High acidity increases the sol-
ubility of many metals, and mines tend
to be in mineral-rich areas. Abandoned
mines are therefore a continuing source
of toxic metals loading in many streams.
Toxic Concentrations of Bioavailable
Metals Along the Stream Corridor
Most metals have a tendency to leave
the dissolved phase and attach to sus-
pended paniculate matter or form in-
soluble precipitates. Conditions that
partition metals into particulate forms
(presence of suspended sediments, dis-
solved and particulate organic carbon,
carbonates, bicarbonates, and other
ions that complex metals) reduce po-
tential bioavailability of metals. Also,
calcium reduces metal uptake, appar-
ently by competing with metals for ac-
tive uptake sites on gill membranes. pH
is also an important water quality factor
in metal bioavailability. In general,
metal solubilities are lower at near neu-
s s
s II o
HO P OEt OtE P OEt || OtE P OEt
I OtEP OEt | OtEP OEt
O ^/>,,_, O O
OtE O OEt OtE P OEt
NO2
p- nitorphenol
OtE P OEt OtE P OEt
I
O
NH2
p- aminophenol
inorganic
phosphate
OH
Figure 2.29: Metabolic reactions for a single
parent pesticide. Particles break down through
processes of hydrolysis, oxidation, reduction,
and photolysis.
tral pH's than in acidic or highly alka-
line waters.
Ecological Functions of Soils
Soil is a living and dynamic resource
that supports life. It consists of inor-
ganic mineral particles of differing sizes
(clay, silt, and sand), organic matter in
various stages of decomposition, nu-
merous species of living organisms,
Physical and Chemical Characteristics
2-45
-------
various water soluble ions, and various
gases and water. These components
each have their own physical and chem-
ical characteristics which can either sup-
port or restrict a particular form of life.
Soils can be mineral or organic depend-
ing on which material makes up the
greater percentage in the soil matrix.
Mineral soils develop in materials
weathered from rocks while organic
soils develop in decayed vegetation.
Both soils typically develop horizons or
layers that are approximately parallel to
the soil surface. The extreme variety of
specific niches or conditions soil can
create has enabled a large variety of
fauna and flora to evolve and live under
those conditions.
Soils, particularly riparian and wetland
soils, contain and support a very high
diversity of flora and fauna both above
and below the soil surface. A large vari-
ety of specialized organisms can be
found below the soil surface, outnum-
bering those above ground by several or-
ders of magnitude. Generally, organisms
seen above ground are higher forms of
life such as plants and wildlife. However,
at and below ground, the vast majority
of life consists of plant roots having the
responsibility of supporting the above
ground portion of the plant; many in-
sects, mollusks, and fungi living on dead
organic matter; and an infinite number
of bacteria which can live on a wide va-
riety of energy sources found in soil.
It is important to identify soil bound-
aries and to understand the differences
in soil properties and functions occur-
ring within a stream corridor in order
to identify opportunities and limita-
tions for restoration. Floodplain and
terrace soils are often areas of dense
population and intensive agricultural
development due to their flat slopes,
proximity to water, and natural fertility.
When planning stream corridor restora-
tion initiatives in developed areas, it is
important to recognize these alterations
and to consider their impacts on goals.
Soils perform vital functions through-
out the landscape. One of the most im-
portant functions of soil is to provide a
physical, chemical, and biological set-
ting for living organisms. Soils support
biological activity and diversity for
plant and animal productivity. Soils
also regulate and partition the flow of
water and the storage and cycling of nu-
trients and other elements in the land-
scape. They filter, buffer, degrade,
immobilize, and detoxify organic and
inorganic materials and provide the me-
chanical support living organisms need.
These hydrologic, geomorphic, and bio-
logic functions involve processes that
help build and sustain stream corridors.
Soil Microbiology
Organic matter provides the main source
of energy for soil microorganisms. Soil
organic matter normally makes up 1 to
5 percent of the total weight in a min-
eral topsoil. It consists of original tissue,
partially decomposed tissue, and humus.
Soil organisms consume roots and vege-
tative detritus for energy and to build
tissue. As the original organic matter is
decomposed and modified by microor-
ganisms, a gelatinous, more resistant
compound is formed. This material is
called humus. It is generally black or
brown in color and exists as a colloid, a
group of small, insoluble particles sus-
pended in a gel. Small amounts of
humus greatly increase a soil's ability to
hold water and nutrient ions which en-
hances plant production. Humus is an
indicator of a large and viable popula-
tion of microorganisms in the soil and it
increases the options available for vege-
tative restoration.
Bacteria play vital roles in the organic
transactions that support plant growth.
They are responsible for three essential
transformations: denitrification, sulfur
2-46
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
oxidation, and nitrogen fixation. Micro-
bial reduction of nitrate to nitrite and
then to gaseous forms of nitrogen is
termed denitrification. A water content
of 60 percent generally limits denitrifi-
cation and the process only occurs at
soil temperatures between 5 ° C and
75 °C. Other soil properties optimizing
the rate of denitrification include a pH
between 6 and 8, soil aeration below
the biological oxygen demand of the or-
ganisms in the soil, sufficient amounts
of water-soluble carbon compounds,
readily available nitrate in the soil, and
the presence of enzymes needed to start
the reaction.
Landscape and Topographic
Position
Soil properties change with topographic
position. Elevation differences generally
mark the boundaries of soils and
drainage conditions in stream corridors.
Different landforms generally have dif-
ferent types of sediment underlying
them. Surface and subsurface drainage
patterns also vary with landforms.
Soils of active channels. The active
channel forms the lowest and usually
youngest surfaces in the stream corri-
dor. There is generally no soil devel-
oped on these surfaces since the
unconsolidated materials forming
the stream bottom and banks are
constantly being eroded, transported,
and redeposited.
Soils of active floodplains. The next
highest surface in the stream corridor
is the flat, depositional surface of the
active floodplain. This surface floods
frequently, every 2 out of 3 years, so
it receives sediment deposition.
Soils of natural levees. Natural levees
are built adjacent to the stream by
deposition of coarser, suspended sed-
iment dropping out of overbank
flows during floods. A gentle back-
slope occurs on the floodplain side
of the natural levee, so the floodplain
becomes lowest at a point far from
the river. Parent materials decrease in
grain size away from the river due to
the decrease in sediment-transport
capacity in the slackwater areas.
Soils of topographic floodplains. Slightly
higher areas within and outside the
active floodplain are defined as the
topographic floodplain. They are
usually inundated less frequently
than the active floodplain, so soils
may exhibit more profile develop-
ment than the younger soils on the
active floodplain.
Soils of terraces. Abandoned flood-
plains, or terraces, are the next high-
est surfaces in stream corridors. These
surfaces rarely flood. Terrace soils, in
general, are coarser textured than
floodplain soils, are more freely
drained, and are separated from
stream processes.
Upon close examination, floodplain
deposits can reveal historical events of
given watersheds. Soil profile develop-
ment offers clues to the recent and geo-
logic history at a site. Intricate and
complex analysis methods such as car-
bon dating, pollen analysis, ratios of
certain isotopes, etc. can be used to
piece together an area's history. Cycles
of erosion or deposition can at times be
linked to catastrophic events like forest
fires or periods of high or low precipita-
tion. Historical impacts of civilization,
such as extensive agriculture or denuda-
tion of forest cover will at times also
leave identifiable evidence in soils.
Soil Temperature and Moisture
Relationships
Soil temperature and moisture control
biological processes occurring in soil.
Average and expected precipitation and
temperature extremes are critical pieces
Physical and Chemical Characteristics
2-47
-------
of information when considering goals
for restoration initiatives. The mean an-
nual soil temperature is usually very
similar to the mean annual air tempera-
ture. Soil temperatures do experience
daily, seasonal, and annual fluctuations
caused by solar radiation, weather pat-
terns, and climate. Soil temperatures are
also affected by aspect, latitude, and ele-
vation.
Soil moisture conditions change sea-
sonally. If changes in vegetation species
and composition are being considered
as part of a restoration initiative, a
graph comparing monthly precipitation
and evapotranspiration for the vegeta-
tion should be constructed. If the water
table and capillary fringe is below the
predicted rooting depth, and the graph
indicates a deficit in available water, ir-
rigation may be required. If no supple-
mental water is available, different plant
species must be considered.
The soil moisture gradient can decrease
from 100 percent to almost zero along
the transriparian continuum as one
progresses from the stream bottom,
across the riparian zone, and into the
higher elevations of the adjacent up-
lands (Johnson and Lowe 1985), which
results in vast differences in moisture
available to vegetation. This gradient in
soil moisture directly influences the
characteristics of the ecological commu-
nities of the riparian, transitional, and
upland zones. These ecological differ-
ences result in the presence of two eco-
tones along the stream corridoran
aquatic-wetland/riparian ecotone and a
non-wetland riparian/floodplain eco-
tonewhich increase the edge effect of
the riparian zone and, therefore, the bi-
ological diversity of the region.
Wetland Soils
Wet or "hydric" soils present special
challenges to plant life. Hydric soils are
present in wetlands areas, creating such
drastic changes in physical and chemical
conditions that most species found in
uplands cannot survive. Hence the com-
position of flora and fauna in wetlands
are vastly different and unique, espe-
cially in wetlands subject to permanent
or prolonged saturation or flooding.
Hydric soils are defined as those that are
saturated, flooded, or ponded long
enough during the growing season to
develop anaerobic conditions in the
upper part. These anaerobic conditions
affect the reproduction, growth, and
survival of plants. The driving process
behind the formation of hydric soils is
flooding and/or soil saturation near the
surface for prolonged periods (usually
more the seven days) during the grow-
ing season (Tiner and Veneman 1989).
The following focuses primarily on
mineral hydric soil properties, but or-
ganic soils such as peat and muck may
be present in the stream corridor.
In aerated soil environments, atmos-
pheric oxygen enters surface soils
through gas diffusion, as soil pores are
mostly filled with air. Aerated soils are
found in well drained uplands, and gen-
erally all areas having a water table well
below the root zone. In saturated soils,
pores are filled with water, which diffuse
gases very slowly compared to the at-
mosphere. Only small amounts of oxy-
gen can dissolve in soil moisture, which
then disperses into the top few inches of
soil. Here, soil microbes quickly deplete
all available free oxygen in oxidizing or-
ganic residue to carbon dioxide. This re-
action produces an anaerobic
chemically reducing environment in
which oxidized compounds are changed
to reduced compounds that are soluble
and also toxic to many plants. The rate
of diffusion is so slow that oxygenated
conditions cannot be reestablished
under such circumstances. Similar mi-
2-48
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
crobial reactions involving decomposi-
tion of organic matter in waterlogged
anaerobic environments produce ethyl-
ene gas, which is highly toxic to plant
roots and has an even stronger effect
than a lack of oxygen. After all free oxy-
gen is utilized, anaerobic microbes re-
duce other chemical constituents of the
soil including nitrates, manganese ox-
ides, and iron oxides, creating a further
reduced condition in the soil.
Prolonged anaerobic reducing condi-
tions result in the formation of readily
visible signs of reduction. The typical
gray colors encountered in wet soils are
the result of reduced iron, and are
known as gleyed soils. After iron oxides
are depleted, sulfates are reduced to sul-
fides, producing the rotten egg odor of
wet soils. Under extremely waterlogged
conditions, carbon dioxide can be re-
duced to methane. Methane gas, also
known as "swamp gas" can be seen at
night, as it fluoresces.
Some wetland plants have evolved spe-
cial mechanisms to compensate for hav-
ing their roots immersed in anoxic
environments. Water lilies, for example,
force a gas exchange within the entire
plant by closing their stomata during
the heat of the day to raise the air pres-
sure within special conductive tissue
(aerenchyma). This process tends to in-
troduce atmospheric oxygen deep into
the root crown, keeping vital tissues
alive. Most emergent wetland plants
simply keep their root systems close to
the soil surface to avoid anaerobic con-
ditions in deeper strata. This is true of
sedges and rushes, for example.
When soils are continually saturated
throughout, reactions can occur equally
throughout the soil profile as opposed
to wet soils where the water level fluctu-
ates. This produces soils with little zo-
nation, and materials tend to be more
uniform. Most differences in texture en-
countered with depth are related to
stratification of sediments sorted by size
during deposition by flowing water.
Clay formation tends to occur in place
and little translocation happens within
the profile, as essentially no water
moves through the soil to transport the
particles. Due to the reactivity of wet
soils, clay formation tends to progress
much faster than in uplands.
Soils which are seasonally saturated or
have a fluctuating water table result in
distinct horizonation within the profile.
As water regularly drains through the
profile, it translocates particles and
transports soluble ions from one layer
to another, or entirely out of the profile.
Often, these soils have a thick horizon
near the surface which is stripped of all
soluble materials including iron; known
as a depleted matrix. Seasonally saturated
soils usually have substantial organic
matter accumulated at the surface,
nearly black in color. The organics add
to the cation exchange capacity of the
soil, but base saturation is low due to
stripping and overabundance of hydro-
gen ions. During non-saturated times,
organic materials are exposed to atmos-
pheric oxygen, and aerobic decomposi-
tion can take place which results in
massive liberation of hydrogen ions.
Seasonally wet soils also do not retain
base metals well, and can release high
concentrations of metals in wet cycles
following dry periods.
Wet soil indicators will often remain in
the soil profile for long periods of time
(even after drainage), revealing the his-
torical conditions which prevailed. Ex-
amples of such indicators are rust
colored iron deposits which at one time
were translocated by water in reduced
form. Organic carbon distribution from
past fluvial deposition cycles or zones
of stripped soils resulting from wetland
situations are characteristics which are
extremely long lived.
Physical and Chemical Characteristics
2-49
-------
Summary
This section provides only a brief overview of the
diverse and complex chemistry; nevertheless, two
key points should be evident to restoration practi-
tioners:
Restoring physical habitat cannot restore biologi-
cal integrity of a system if there are water quality
constraints on the ecosystem.
Restoration activities may interact in a variety of
complex ways with water quality, affecting both
the delivery and impact of water quality stres-
sors.
Table 2.9 shows how a sample selection of com-
mon stream restoration and watershed manage-
ment practices may interact with the water quality
parameters described in this section.
Table 2.9: Potential water quality impacts of selected stream restoration and watershed management practices.
Restoration
Activities
Reduction of
land-disturbing
activities
Limit impervious
surface area in
the watershed
Restore riparian
vegetation
Restore
wetlands
Stabilize channel
and restore
under-cut banks
Create drop
structures
Reestablish
riffle substrate
Fine I Water I Salinity
Sediment I Temperature I
Loads
Dissolved I Nutrients I Toxics
Oxygen
Decrease Decrease
Decrease Decrease
Decrease Decrease
Decrease Increase/
decrease
Decrease Decrease
Increase Negligible
effect
Negligible Negligible
effect effect
Decrease Increase/ Increase
decrease
Negligible Increase Increase
effect
Decrease Decrease
Decrease Decrease
Decrease Decrease Increase Decrease Decrease
Increase/ Increase/ Decrease Increase
decrease decrease
Increase
Decrease Decrease Increase Decrease Negligible
effect
Negligible Increase/ Increase
effect decrease
Negligible Increase/ Increase
effect decrease
Negligible Decrease
effect
Negligible Negligible
effect effect
2-50
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
2.D Biological Community Characteristics
Successful stream restoration is based
on an understanding of the relation-
ships among physical, chemical, and bi-
ological processes at varying time scales.
Often, human activities have acceler-
ated the temporal progression of these
processes, resulting in unstable flow
patterns and altered biological structure
and function of stream corridors. This
section discusses the biological struc-
ture and functions of stream corridors
in relation to geomorphologic, hydro-
logic, and water quality processes. The
interrelations between the watershed
and the stream, as well as the cause and
effects of disturbances to these interrela-
tionships are also discussed. Indices
and approaches for evaluating stream
corridor functions are provided in
Chapter 7.
Terrestrial Ecosystems
The biological community of a stream
corridor is determined by the character-
istics of both terrestrial and aquatic
ecosystems. Accordingly, the discussion
of biological communities in stream
corridors begins with a review of terres-
trial ecosystems.
Ecological Role of Soil
Terrestrial ecosystems are fundamen-
tally tied to processes within the soil.
The ability of a soil to store and cycle
nutrients and other elements depends
on the properties and microclimate
(i.e., moisture and temperature) of the
soil, and the soil's community of organ-
isms (Table 2.10). These factors also de-
termine its effectiveness at filtering,
buffering, degrading, immobilizing, and
detoxifying other organic and inorganic
materials.
Terrestrial Vegetation
The ecological integrity of stream corri-
dor ecosystems is directly related to the
integrity and ecological characteristics
of the plant communities that make up
and surround the corridor. These plant
communities are a valuable source of
energy for the biological communities,
provide physical habitat, and moderate
solar energy fluxes to and from the sur-
rounding aquatic and terrestrial ecosys-
tems. Given adequate moisture, light,
and temperature, the vegetative com-
munity grows in an annual cycle of ac-
tive growth/production, senescence, and
relative dormancy. The growth period is
subsidized by incidental solar radiation,
which drives the photosynthetic process
through which inorganic carbon is con-
verted to organic plant materials. A por-
tion of this organic material is stored as
above- and below-ground biomass,
while a significant fraction of organic
matter is lost annually via senescence,
fractionation, and leaching to the or-
ganic soil layer in the form of leaves,
twigs, and decaying roots. This organic
fraction, rich in biological activity of
microbial flora and microfauna, repre-
sents a major storage and cycling pool
of available carbon, nitrogen, phospho-
rus, and other nutrients.
The distribution and characteristics of
vegetative communities are determined
by climate, water availability, topo-
graphic features, and the chemical and
physical properties of the soil, including
moisture and nutrient content. The
characteristics of the plant communities
directly influence the diversity and in-
tegrity of the faunal communities. Plant
communities that cover a large area and
that are diverse in their vertical and hor-
izontal structural characteristics can
support far more diverse faunal com-
REVERSE
I
Review Section
C for further
discussion of
the ecological
functions of
soils.
Biological Community Characteristics
2-51
-------
Macro Subsisting largely on plant materials
Small mammalssquirrels, gophers, woodchucks, mice, shrews
Insectsspringtails, ants, beetles, grubs, etc.
Millipedes
Sowbugs (woodlice)
Mites
Slugs and snails
Earthworms
Largely predatory
Moles
Insectsmany ants, beetles, etc.
Mites, in some cases
Centipedes
Spiders
Micro Predatory or parasitic or subsisting on plant residues
Nematodes
Protozoa
Rotifers
Roots of higher plants
Algae
Green
Blue-green
Diatoms
Fungi
Mushroom fungi
Yeasts
Molds
Actinomycetes of many kind
Bacteria
Aerobic Autotrophic
Heterotrophic
Anaerobic Autotrophic
Heterotrophic
Table 2.10: Groups of organisms commonly
present in soils.
munities than relatively homogenous
plant communities, such as meadows.
As a result of the complex spatial and
temporal relationships that exist be-
tween floral and faunal communities,
current ecological characteristics of
these communities reflect the recent
historical (100 years or less) physical
conditions of the landscape.
The quantity of terrestrial vegetation, as
well as its species composition, can di-
rectly affect stream channel characteris-
tics. Root systems in the streambank
can bind bank sediments and moderate
erosion processes. Trees and smaller
woody debris that fall into the stream
can deflect flows and induce erosion at
some points and deposition at others.
Thus woody debris accumulation can
influence pool distribution, organic
matter and nutrient retention, and the
formation of microhabitats that are im-
portant fish and invertebrate aquatic
communities.
Streamflow also can be affected by the
abundance and distribution of terres-
trial vegetation. The short-term effects
of removing vegetation can result in an
immediate short-term rise in the local
water table due to decreased evapotran-
spiration and additional water entering
the stream. Over the longer term, how-
ever, after removal of vegetation, the
baseflow of streams can decrease and
water temperatures can rise, particularly
in low-order streams. Also, removal of
vegetation can cause changes in soil
temperature and structure, resulting in
decreased movement of water into and
through the soil profile. The loss of sur-
face litter and the gradual loss of or-
ganic matter in the soil also contribute
to increased surface runoff and de-
creased infiltration.
In most instances, the functions of veg-
etation that are most apparent are those
that influence fish and wildlife. At the
landscape level, the fragmentation of
native cover types has been shown to
significantly influence wildlife, often fa-
voring opportunistic species over those
requiring large blocks of contiguous
habitat. In some systems, relatively
2-52
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
small breaks in corridor continuity can
have significant impacts on animal
movement or on the suitability of
stream conditions to support certain
aquatic species. In others, establishing
corridors that are structurally different
from native systems or that are inappro-
priately configured can be equally dis-
ruptive. Narrow corridors that are
essentially edge habitat may encourage
generalist species, nest parasites, and
predators, and, where corridors have
been established across historic barriers
to animal movement, they can disrupt
the integrity of regional animal assem-
blages (Knopf et al. 1988).
Landscape Scale
The ecological characteristics and distri-
bution of plant communities in a wa-
tershed influence the movement of
water, sediment, nutrients, and wildlife.
Stream corridors provide links with
other features of the landscape. Links
may involve continuous corridors be-
tween headwater and valley floor
ecosystems or periodic interactions be-
tween terrestrial systems. Wildlife use
corridors to disperse juveniles, to mi-
grate, and to move between portions of
their home range. Corridors of a natural
origin are preferred and include streams
and rivers, riparian strips, mountain
passes, isthmuses, and narrow straits
(Payne and Bryant 1995).
It is important to understand the differ-
ences between a stream-riparian ecosys-
tem and a river-floodplain ecosystem.
Flooding in the stream-riparian ecosys-
tem is brief and unpredictable. The ri-
parian zone supplies nutrients, water,
and sediment to the stream channel,
and riparian vegetation regulates tem-
perature and light. In the river-flood-
plain ecosystem, floods are often more
predictable and longer lasting, the river
channel is the donor of water, sedi-
ment, and inorganic nutrients to the
floodplain, and the influx of turbid and
cooler channel water influences light
penetration and temperature of the
inundated floodplain.
Stream Corridor Scale
At the stream corridor scale, the compo-
sition and regeneration patterns of veg-
etation are characterized in terms of
horizontal complexity. Floodplains along
unconstrained channels typically are
vegetated with a mosaic of plant com-
munities, the composition of which
varies in response to available surface
and ground water, differential patterns
of flooding, fire, and predominant
winds, sediment deposition, and oppor-
tunities for establishing vegetation.
A broad floodplain of the southern,
midwestern, or eastern United States
may support dozens of relatively dis-
tinct forest communities in a complex
mosaic reflecting subtle differences in
soil type and flood characteristics (e.g.,
frequency, depth, and duration). In
contrast, while certain western stream
systems may support only a few woody
species, these systems may be struc-
turally complex due to constant rework-
ing of substrates by the stream, which
produces a mosaic of stands of varying
ages. The presence of side channels,
oxbow lakes, and other topographic
variation can be viewed as elements of
structural variation at the stream corri-
dor level. Riparian areas along con-
strained stream channels may consist
primarily of upland vegetation orga-
nized by processes largely unrelated to
stream characteristics, but these areas
may have considerable influence on the
stream ecosystem.
The River Continuum Concept, as dis-
cussed in Chapter 1, is also generally
applicable to the vegetative components
of the riparian corridor. Riparian vegeta-
tion demonstrates both a transriparian
gradient (across the valley) and an
Biological Community Characteristics
2-53
-------
intra-riparian (longitudinal, eleva-
tional) gradient (Johnson and Lowe
1985). In the west, growth of riparian
vegetation is increased by the "canyon
effect" resulting when cool moist air
spills downslope from higher elevations
(Figure 2.30). This cooler air settles in
canyons and creates a more moist mi-
crohabitat than occurs on the surround-
ing slopes. These canyons also serve as
water courses. The combination of
moist, cooler edaphic and atmospheric
conditions is conducive to plant and
animal species at lower than normal al-
titudes, often in disjunct populations or
in regions where they would not other-
wise occur (Lowe and Shannon 1954).
Plant Communities
The sensitivity of animal communities
to vegetative characteristics is well rec-
ognized. Numerous animal species are
associated with particular plant com-
munities, many require particular devel-
opmental stages of those communities
(e.g., old-growth), and some depend on
particular habitat elements within those
communities (e.g., snags). The structure
of streamside plant communities also
directly affects aquatic organisms by
providing inputs of appropriate organic
materials to the aquatic food web, by
shading the water surface and providing
cover along banks, and by influencing
instream habitat structure through in-
Figure 2.30: Canyon effect. Cool moist air settles in canyons and creates microhabitat that occurs
on surrounding slopes.
2-54
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
puts of woody debris (Gregory et al.
1991).
Plant communities can be viewed in
terms of their internal complexity (Fig-
ure 2.31). Complexity may include the
number of layers of vegetation and the
species comprising each layer; competi-
tive interactions among species; and the
presence of detrital components, such
as litter, downed wood, and snags. Veg-
etation may contain tree, sapling, shrub
(subtree), vine, and herbaceous sub-
shrub (herb-grass-forb) layers. Microto-
pographic relief and the ability of water
to locally pond also may be regarded as
characteristic structural components.
Vertical complexity, described in the con-
cept of diversity of strata or foliage
height diversity in ecological literature,
was important to studies of avian habi-
tat by Carothers et al. (1974) along the
Verde River, a fifth- or sixth-order
stream in central Arizona. Findings
showed a high correlation between ri-
parian bird species diversity and foliage
height diversity of riparian vegetation
(Carothers et al. 1974). Short (1985)
demonstrated that more structurally di-
verse vegetative habitats support a
greater number of guilds (groups of
species with closely related niches in a
community) and therefore a larger
number of species.
Species and age composition of vegeta-
tion structure also can be extremely im-
portant. Simple vegetative structure,
such as an herbaceous layer without
woody overstory or old woody riparian
trees without smaller size classes, cre-
ates fewer niches for guilds. The fewer
guilds there are, the fewer species there
are. The quality and vigor of the vegeta-
tion can affect the productivity of fruits,
seeds, shoots, roots, and other vegeta-
tive material, which provide food for
wildlife. Poorer vigor can result in less
food and fewer consumers (wildlife).
Increasing the patch size (area) of a
streamside vegetation type, increasing
the number of woody riparian tree size
classes, and increasing the number of
species and growth forms (herb, shrub,
tree) of native riparian-dependent vege-
tation can increase the number of
guilds and the amount of forage, result-
ing in increased species richness and
biomass (numbers). Restoration tech-
niques can change the above factors.
The importance of horizontal complex-
ity within stream corridors to certain
animal species also has been well estab-
lished. The characteristic compositional,
structural, and topographic complexity
of southern floodplain forests, for ex-
ample, provides the range of resources
and foraging conditions required by
many wintering waterfowl to meet par-
ticular requirements of their life cycles
at the appropriate times (Fredrickson
1978); similar complex relationships
have been reported for other vertebrates
and invertebrates in floodplain habitats
(Wharton et al. 1982). In parts of the
arid West, the unique vegetation struc-
ture in riparian systems contrasts dra-
trees
herbaceous
subshrubs
Figure 2.31: Vertical complexity. Complexity
may include a number of layers of vegetation.
Biological Community Characteristics
2-55
-------
matically with the surrounding uplands
and provides essential habitat for many
animals (Knopf et al. 1988). Even
within compositionally simple riparian
systems, different developmental stages
may provide different resources.
Plant communities are distributed on
floodplains in relation to flood depth,
duration, and frequency, as well as vari-
ations in soils and drainage condition.
Some plant species, such as cottonwood
(Populus sp.), willows (Salix sp.), and
silver maple (Acer saccharinum), are
adapted to colonization of newly de-
posited sediments and may require very
specific patterns of flood recession dur-
ing a brief period of seedfall to be suc-
cessfully established (Morris et al. 1978,
Rood and Mahoney 1990). The resul-
tant pattern is one of even-aged tree
stands established at different intervals
and locations within the active meander
belt of the stream. Other species, such
as the bald cypress (Taxodium dis-
tichum], are particularly associated with
oxbow lakes formed when streams cut
off channel segments, while still others
are associated with microtopographic
variations within floodplains that re-
flect the slow migration of a stream
channel across the landscape.
Plant communities are dynamic and
change over time. The differing regener-
ation strategies of particular vegetation
types lead to characteristic patterns of
plant succession following disturbances
in which pioneer species well-adapted
to bare soil and plentiful light are grad-
ually replaced by longer-lived species
that can regenerate under more shaded
and protected conditions. New distur-
bances reset the successional process.
Within stream corridors, flooding,
channel migration, and, in certain bio-
mes, fire, are usually the dominant nat-
ural sources of disturbance. Restoration
practitioners should understand pat-
terns of natural succession in a stream
corridor and should take advantage of
the successional process by planting
hardy early-successional species to sta-
bilize an eroding streambank, while
planning for the eventual replacement
of these species by longer-lived and
higher-successional species.
Terrestrial Fauna
Stream corridors are used by wildlife
more than any other habitat type
(Thomas et al. 1979) and are a major
source of water to wildlife populations,
especially large mammals. For example,
60 percent of Arizona's wildlife species
depend on riparian areas for survival
(Ohmart and Anderson 1986). In the
Great Basin area of Utah and Nevada,
288 of the 363 identified terrestrial ver-
tebrate species depend on riparian
zones (Thomas et al. 1979). Because of
their wide suitability for upland and ri-
parian species, midwestern stream corri-
dors associated with prairie grasslands
support a wider diversity of wildlife
than the associated uplands. Stream cor-
ridors play a large role in maintaining
biodiversity for all groups of vertebrates.
The faunal composition of a stream cor-
ridor is a function of the interaction of
food, water, cover, and spatial arrange-
ment (Thomas et al. 1979). These habi-
tat components interact in multiple
ways to provide eight habitat features of
stream corridors:
Presence of permanent sources of
water.
High primary productivity and bio-
mass.
Dramatic spatial and temporal con-
trasts in cover types and food avail-
ability.
Critical microclimates.
Horizontal and vertical habitat diver-
sity.
2-56
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
Maximized edge effect.
Effective seasonal migration routes.
High connectivity between vegetated
patches.
Stream corridors offer the optimal habi-
tat for many forms of wildlife because
of the proximity to a water source and
an ecological community that consists
primarily of hardwoods in many parts
of the country, which provide a source
of food, such as nectar, catkins, buds,
fruit, and seeds (Harris 1984). Up-
stream sources of water, nutrients, and
energy ultimately benefit downstream
locations. In turn, the fish and wildlife
return and disperse some of the nutri-
ents and energy to uplands and wet-
lands during their movements and
migrations (Harris 1984).
Water is especially critical to fauna in
areas such as the Southwest or Western
Prairie regions of the U.S. where stream
corridors are the only naturally occur-
ring permanent sources of water on the
landscape. These relatively moist envi-
ronments contribute to the high pri-
mary productivity and biomass of the
riparian area, which contrasts dramati-
cally with surrounding cover types and
food sources. In these areas, stream cor-
ridors provide critical microclimates
that ameliorate the temperature and
moisture extremes of uplands by pro-
viding water, shade, evapotranspiration,
and cover.
The spatial distribution of vegetation is
also a critical factor for wildlife. The lin-
ear arrangement of streams results in a
maximized edge effect that increases
species richness because a species can
simultaneously access more than one
cover (or habitat) type and exploit the
resources of both (Leopold 1933).
Edges occur along multiple habitat
types including the aquatic, riparian,
and upland habitats.
Forested connectors between habitats
establish continuity between forested
uplands that may be surrounded by un-
forested areas. These act as feeder lines
for dispersal and facilitate repopulation
by plants and animals. Thus, connectiv-
ity is very important for retaining biodi-
versity and genetic integrity on a
landscape basis.
However, the linear distribution of
habitat, or edge effect, is not an effec-
tive indicator of habitat quality for all
species. Studies in island biogeography,
using habitat islands rather than
oceanic islands, demonstrate that a
larger habitat island supports both a
larger population of birds and also a
larger number of species (Wilson and
Carothers 1979). Although a continu-
ous corridor is most desirable, the next
preferable situation is minimal frag-
mentation, i.e., large plots ("islands")
of riparian vegetation with minimal
spaces between the large plots.
Reptiles and Amphibians
Nearly all amphibians (salamanders,
toads, and frogs) depend on aquatic
habitats for reproduction and overwin-
tering. While less restricted by the pres-
ence of water, many reptiles are found
primarily in stream corridors and ripar-
ian habitats. Thirty-six of the 63 reptile
and amphibian species found in west-
central Arizona were found to use ripar-
ian zones. In the Great Basin, 11 of 22
reptile species require or prefer riparian
zones (Ohmart and Anderson 1986).
Birds
Birds are the most commonly observed
terrestrial wildlife in riparian corridors.
Nationally, over 250 species have been
reported using riparian areas during
some part of the year.
The highest known density of nesting
birds in North America occurs in south-
western cottonwood habitats (Carothers
Biological Community Characteristics
2-57
-------
and Johnson 1971). Seventy-three per-
cent of the 166 breeding bird species in
the Southwest prefer riparian habitats
(Johnson et al. 1977).
Bird species richness in midwestern
stream corridors reflects the vegetative
diversity and width of the corridor.
Over half of these breeding birds are
species that forage for insects on foliage
(vireos, warblers) or species that forage
for seeds on the ground (doves, orioles,
grosbeaks, sparrows). Next in abun-
dance are insectivorous species that for-
age on the ground or on trees
(thrushes, woodpeckers).
Smith (1977) reported that the distrib-
ution of bird species in forested habi-
tats of the Southeast was closely linked
to soil moisture. Woodcock (Scolopax
minor) and snipe (Gallinago gallinago),
red-shouldered hawks (Buteo lineatus),
hooded and prothonotary warblers
(Wilsonia citrina, Protonotaria citrea),
and many other passerines in the
Southeast prefer the moist ground con-
ditions found in riverside forests and
shrublands for feeding. The cypress and
mangrove swamps along Florida's wa-
terways harbor many species found al-
most nowhere else in the Southeast.
Mammals
The combination of cover, water, and
food resources in riparian areas make
them desirable habitat for large mam-
mals such as mule deer (Odocoileus
hemionus), white-tailed deer (Odocoileus
virginianus), moose (Alces alces), and elk
(Cervus elaphus) that can use multiple
habitat types. Other mammals depend
on riparian areas in some or all of their
range. These include otter (Lutra
canadensis), ringtail (Bassarisdus astutus),
raccoon (Procyon lotor), beaver (Castor
canadensis), muskrat (Ondatra zibethi-
cus), swamp rabbit (Sylvilagus aquati-
cus), short-tailed shrew (Blarina
brevicauda), and mink (Mustela vison).
Riparian areas provide tall dense cover
for roosts, water, and abundant prey for
a number of bat species, including the
little brown bat (Myotis lucifugus), big
brown bat (Eptesicus fuscus), and the
pallid bat (Antrozous pallidus). Brinson
et al. (1981) tabulated results from sev-
eral studies on mammals in riparian
areas of the continental U.S. They con-
cluded that the number of mammal
species generally ranges from five to 30,
with communities including several
furbearers, one or more large mammals,
and a few small to medium mammals.
Hoover and Wills (1984) reported 59
species of mammals in cottonwood ri-
parian woodlands of Colorado, second
only to pinyon-juniper among eight
other forested cover types in the region.
Fifty-two of the 68 mammal species
found in west-central Arizona in Bureau
of Land Management inventories use ri-
parian habitats. Stamp and Ohmart
(1979) and Cross (1985) found that ri-
parian areas had a greater diversity and
biomass of small mammals than adja-
cent upland areas.
The contrast between the species diver-
sity and productivity of mammals in
the riparian zone and that of the sur-
rounding uplands is especially high in
arid and semiarid regions. However,
bottomland hardwoods in the eastern
U.S. also have exceptionally high habi-
tat values for many mammals. For ex-
ample, bottomland hardwoods support
white-tail deer populations roughly
twice as large as equivalent areas of up-
land forest (Glasgow and Noble 1971).
Stream corridors are themselves influ-
enced by certain animal activities (For-
man 1995). For example, beavers build
dams that cause ponds to form within a
stream channel or in the floodplain. The
pond kills much of the existing vegeta-
tion, although it does create wetlands
and open water areas for fish and mi-
2-58
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
gratory waterfowl. If appropriate woody
plants in the floodplain are scarce,
beavers extend their cutting activities
into the uplands and can significantly
alter the riparian and stream corridors.
Over time, the pond is replaced by a
mudflat, which becomes a meadow and
eventually gives way to woody succes-
sional stages. Beaver often then build a
dam at a new spot, and the cycle begins
anew with only a spatial displacement.
The sequence of beaver dams along a
stream corridor may have major effects
on hydrology, sedimentation, and min-
eral nutrients (Forman 1995). Water
from stormflow is held back, thereby af-
fording some measure of flood control.
Silts and other fine sediments accumu-
late in the pond rather than being
washed downstream. Wetland areas
usually form, and the water table rises
upstream of the dam. The ponds com-
bine slow flow, near-constant water lev-
els, and low turbidity that support fish
and other aquatic organisms. Birds may
use beaver ponds extensively. The wet-
lands also have a relatively constant
water table, unlike the typical fluctua-
tions across a floodplain. Beavers cut-
ting trees diminish the abundance of
such species as elm (Ulmus spp.) and
ash (Fraxinus spp.) but enhance the
abundance of rapidly sprouting species,
such as alder (Alnus spp.), willow, and
poplar (Populus spp.).
Aquatic Ecosystems
Aquatic Habitat
The biological diversity and species
abundance in streams depend on the
diversity of available habitats. Naturally
functioning, stable stream systems pro-
mote the diversity and availability of
habitats. This is one of the primary rea-
sons stream stability and the restoration
of natural functions are always consid-
ered in stream corridor restoration ac-
tivities. A stream's cross-sectional shape
and dimensions, its slope and confine-
ment, the grain-size distribution of bed
sediments, and even its planform affect
aquatic habitat. Under less disturbed
situations, a narrow, steep-walled cross
section provides less physical area for
habitat than a wider cross section with
less steep sides, but may provide more
biologically rich habitat in deep pools
compared to a wider, shallower stream
corridor. A steep, confined stream is a
high-energy environment that may limit
habitat occurrence, diversity, and stabil-
ity. Many steep, fast flowing streams are
coldwater salmonid streams of high
value. Unconfined systems flood fre-
quently, which can promote riparian
habitat development. Habitat increases
with stream sinuosity. Uniform sedi-
ment size in a streambed provides less
potential habitat diversity than a bed
with many grain sizes represented.
Habitat subsystems occur at different
scales within a stream system (Frissell
et al. 1986) (Figure 2.32). The grossest
scale, the stream system itself, is mea-
sured in thousands of feet, while seg-
ments are measured in hundreds of feet
and reaches are measured in tens of
feet. A reach system includes combina-
tions of debris dams, boulder cascades,
rapids, step/pool sequences, pool/riffle
sequences, or other types of streambed
forms or "structures," each of which
could be 10 feet or less in scale. Fris-
sell's smallest scale habitat subsystem
includes features that are a foot or less
in size. Examples of these microhabitats
include leaf or stick detritus, sand or silt
over cobbles or other coarse material,
moss on boulders, or fine gravel
patches.
Steep slopes often form a step/pool se-
quence in streams, especially in cobble,
boulder, and bedrock streams. Each
step acts as a miniature grade stabiliza-
tion structure. The steps and pools work
Biological Community Characteristics
2-59
-------
leaf and stick
detritus in
margin
sand-silt
over cobbles
transverse bar
over cobbles
moss on
boulder
Stream Segment
Segment System
7
debris dam
Reach System
fine gravel
patch
"Pool/Riffle" System Microhabitat System
Figure 2.32: Hierarchical organization of a stream system and its habitat subsystems.
Approximate linear spatial scale, appropriate to second- or third-order mountain stream.
together to distribute the excess energy
available in these steeply sloping sys-
tems. They also add diversity to the
habitat available. Cobble- and gravel-
bottomed streams at less steep slopes
form pool/riffle sequences, which also
increase habitat diversity. Pools provide
space, cover, and nutrition to fish and
they provide a place for fish to seek
shelter during storms, droughts, and
other catastrophic events. Upstream mi-
gration of many salmonid species typi-
cally involves rapid movements through
shallow areas, followed by periods of
rest in deeper pools (Spence et al.
1996).
Wetlands
Stream corridor restoration initiatives
may include restoration of wetlands
such as riverine-type bottomland hard-
wood systems or riparian wetlands.
While wetland restoration is a specific
topic better addressed in other references
(e.g., Kentula et al. 1992), a general dis-
cussion of wetlands is provided here.
Stream corridor restoration initiatives
should be designed to protect or restore
the functions of associated wetlands.
A wetland is an ecosystem that depends
on constant or recurrent shallow inun-
dation or saturation at or near the sur-
face of the substrate. The minimum
essential characteristics of a wetland are
recurrent, sustained inundation or satu-
ration at or near the surface and the
presence of physical, chemical, and bio-
logical features that reflect recurrent
sustained inundation or saturation.
Common diagnostic features of wet-
lands are hydric soils and hydrophytic
vegetation. These features will be pre-
sent except where physicochemical, bi-
otic, or anthropogenic factors have
removed them or prevented their devel-
opment (National Academy of Sciences
1995). Wetlands may occur in streams,
riparian areas, and floodplains of the
stream corridor. The riparian area or
zone may contain both wetlands and
non-wetlands.
Wetlands are transitional between terres-
trial and aquatic systems where the
water table is usually at or near the
surface or the land is covered by shallow
water (Cowardin et al. 1979). For vege-
tated wetlands, water creates conditions
that favor the growth of hydrophytes
plants growing in water or on a sub-
2-60
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
strate that is at least periodically defi-
cient in oxygen as a result of excessive
water content (Cowardin et al. 1979)
and promotes the development of hy-
dric soilssoils that are saturated,
flooded, or ponded long enough during
the growing season to develop anaero-
bic conditions in the upper part (Na-
tional Academy of Sciences 1995).
Wetland functions include fish and
wildlife habitat, water storage, sediment
trapping, flood damage reduction,
water quality improvement/pollution
control, and ground water recharge.
Wetlands have long been recognized as
highly productive habitats for threat-
ened and endangered fish and wildlife
species. Wetlands provide habitat for
60 to 70 percent of the animal species
federally listed as threatened or endan-
gered (Lohoefner 1997).
The Federal Geographic Data Commit-
tee has adopted the U.S. Fish and
Wildlife Service's Classification of Wet-
lands and Deepwater Habitats of the
United States (Cowardin et al. 1979)
as the national standard for wetlands
classification. The Service's National
Wetlands Inventory (NWI) uses this
system to carry out its congressionally
mandated role of identifying, classify-
ing, mapping, and digitizing data on
wetlands and deepwater habitats. This
system, which defines wetlands consis-
tently with the National Academy of
Science's reference definition, includes
Marine, Estuarine, Riverine, Lacustrine,
and Palustrine systems. The NWI has
also developed protocols for classifying
and mapping riparian habitats in the
22 coterminous western states.
The riverine system under Cowardin's
classification includes all wetlands and
deepwater habitats contained within a
channel except wetlands dominated by
trees, shrubs, persistent emergents,
emergent mosses, or lichens and habi-
Riparian Mapping
The riparian zone is a classic example of the maximized
value that occurs when two or more habitat types meet.
There is little question of the substantial value of riparian
habitats in the United States. The Fish and Wildlife
Service has developed protocols to classify and map
riparian areas in the West in conjunction with the
National Wetlands Inventory (NWI). NWI will map ripari-
an areas on a 100 percent user-pay basis. No formal
riparian mapping effort has been initiated. The NWI is
congressionally mandated to identify, classify, and digi-
tize all wetlands and deepwater habitats in the United
States. For purposes of riparian mapping, the NWI has
developed a riparian definition that incorporates biologi-
cal information consistent with many agencies and
applies information according to cartographic principles.
For NWI mapping and classification purposes, a final def-
inition for riparian has been developed:
Riparian areas are plant communities contiguous to and
affected by surface and subsurface hydrological features
of perennial or intermittent lotic and ientic water bodies
(rivers, streams, lakes, and drainage ways). Riparian areas
have one or both of the following characteristics: (1) dis-
tinctly different vegetative species than adjacent areas;
and (2) species similar to adjacent areas but exhibiting
more vigorous or robust growth forms. Riparian areas
are usually transitional between wetland and upland.
The definition applies primarily to regions of the lower
48 states in the arid west where the mean annual pre-
cipitation is 16 inches or less and the mean annual evap-
oration exceeds mean annual precipitation. For purposes
of this mapping, the riparian system is subdivided into
subsystems, classes, subclasses, and dominance types.
(USFWS 1997)
tats with water containing ocean-
derived salts in excess of 0.5 parts per
thousand (ppt).
It is bounded on the upstream end by
uplands and on the downstream end at
the interface with tidal wetlands having
a concentration of ocean-derived salts
that exceeds 0.5 ppt. Riverine wetlands
Biological Community Characteristics
2-61
-------
are bounded perpendicularly on the
landward side by upland, the channel
bank (including natural and manufac-
tured levees), or by Palustrine wetlands.
In braided streams, riverine wetlands
are bounded by the banks forming the
outer limits of the depression within
which the braiding occurs.
Vegetated floodplain wetlands of the
river corridor are classified as Palustrine
under this system. The Palustrine sys-
tem was developed to group the vege-
tated wetlands traditionally called by
such names as marsh, swamp, bog, fen,
and prairie pothole and also includes
small, shallow, permanent, or intermit-
tent water bodies often called ponds.
Palustrine wetlands may be situated
shoreward of lakes, river channels, or
estuaries, on river floodplains, in iso-
lated catchments, or on slopes. They
also may occur as islands in lakes or
rivers. The Palustrine system includes all
nontidal wetlands dominated by trees,
shrubs, persistent emergents, emergent
mosses and lichens, and all such wet-
lands that occur in tidal areas where
salinity due to ocean-derived salts is
below 0.5 ppt. The Palustrine system is
bounded by upland or by any of the
other four systems. They may merge
with non-wetland riparian habitat
where hydrologic conditions cease to
support wetland vegetation or may be
totally absent where hydrologic condi-
tions do not support wetlands at all
(Cowardin et al. 1979).
The hydrogeomorphic (HGM) approach is
a system that classifies wetlands into
similar groups for conducting functional
assessments of wetlands. Wetlands are
classified based on geomorphology,
water source, and hydrodynamics. This
allows the focus to be placed on a
group of wetlands that function much
more similarly than would be the case
without classifying them. Reference wet-
lands are used to develop reference
standards against which a wetland is
evaluated (Brinson 1995).
Under the HGM approach, riverine wet-
lands occur in floodplains and riparian
corridors associated with stream chan-
nels. The dominant water sources are
overbank flow or subsurface connec-
tions between stream channel and wet-
lands. Riverine wetlands lose water by
surface and subsurface flow returning to
the stream channel, ground water
recharge, and evapotranspiration. At the
extension closest to the headwaters,
riverine wetlands often are replaced by
slope or depressional wetlands where
channel bed and bank disappear, or
they may intergrade with poorly drained
flats and uplands. Usually forested, they
extend downstream to the intergrade
with estuarine fringe wetlands. Lateral
extent is from the edge of the channel
perpendicularly to the edge of the flood-
plain. In some landscape situations,
riverine wetlands may function hydro-
logically more like slope wetlands, and
in headwater streams with little or no
floodplain, slope wetlands may lie adja-
cent to the stream channel (Brinson et
al. 1995). Table 2.11 summarizes func-
tions of riverine wetlands under the
HGM approach. The U.S. Fish and
Wildlife Service is testing an operational
draft set of hydrogeomorphic type de-
scriptors to help bridge the gap between
the Cowardin system and the HGM ap-
proach (Tiner 1997).
For purposes of regulation under Sec-
tion 404 of the Clean Water Act, only
areas with wetland hydrology, hy-
drophytic vegetation, and hydric soils
are classified as regulated wetlands.
As such, they represent a subset of the
areas classified as wetlands under the
Cowardin system. However, many areas
classified as wetlands under the Cow-
ardin system, but not classified as wet-
lands for purposes of Section 404, are
nevertheless subject to regulation be-
2-62
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
cause they are part of the Waters of the
United States.
Aquatic Vegetation and Fauna
Stream biota are often classified in seven
groupsbacteria, algae, macrophytes
(higher plants), protists (amoebas, fla-
gellates, ciliates), microinvertebrates
(invertebrates less than 0.02 inch in
length, such as rotifers, copepods, ostra-
cods, and nematodes), macroinverte-
brates (invertebrates greater than 0.02
inch in length, such as mayflies, stone-
flies, caddisflies, crayfish, worms,
clams, and snails), and vertebrates
(fish, amphibians, reptiles, and mam-
mals) (Figure 2.33). The discussion
of the River Continuum Concept in
Chapter 1, provides an overview of the
major groups of organisms found in
streams and how these assemblages
change from higher order to lower
order streams.
Undisturbed streams can contain a re-
markable number of species. For exam-
ple, a comprehensive inventory of
stream biota in a small German stream,
the Breitenbach, found more than 1,300
species in a 1.2-mile reach. Lists of
algae, macroinvertebrates, and fish likely
to be found at potential restoration sites
may be obtained from state or regional
inventories. The densities of such stream
biota are shown in Table 2.12.
Aquatic plants usually consist of algae
and mosses attached to permanent
stream substrates. Rooted aquatic vege-
tation may occur where substrates are
suitable and high currents do not scour
the stream bottom. Luxuriant beds of
vascular plants may grow in some areas
such as spring-fed streams in Florida
where water clarity, substrates, nutrients,
and slow water velocities exist. Bedrock
or stones that cannot be moved easily
by stream currents are often covered by
mosses and algae and various forms of
Hydrologic
Dynamic surface water storage
Long-term surface water storage
Subsurface storage of water
Energy dissipation
Moderation of ground-water flow or discharge
Biogeochemical Nutrient cycling
Plant habitat
Removal of elements and compounds
Retention of particulates
Organic carbon export
Maintain characteristic plant communities
Maintain characteristic detrital biomass
Animal habitat | Maintain spatial habitat structure
Maintain interspersion and connectivity
Maintain distribution and abundance of invertebrates
Maintain distribution and abundance of vertebrates
Table 2.11: Functions of riverine wetlands.
Source: Brinson et al. 1995.
micro- and macroinvertebrates (Ruttner
1963). Planktonic plant forms are usu-
ally limited but may be present where
the watershed contains lakes, ponds,
floodplain waters, or slow current areas
(Odum 1971).
The benthic invertebrate community of
streams may contain a variety of biota,
including bacteria, protists, rotifers, bry-
ozoans, worms, crustaceans, aquatic in-
sect larvae, mussels, clams, crayfish, and
other forms of invertebrates. Aquatic in-
vertebrates are found in or on a multi-
tude of microhabitats in streams
including plants, woody debris, rocks,
interstitial spaces of hard substrates, and
soft substrates (gravel, sand, and muck).
Invertebrate habitats exist at all vertical
strata including the water surface, the
water column, the bottom surface, and
deep within the hyporheic zone.
Unicellular organisms and microinver-
tebrates are the most numerous biota in
streams. However, larger macroinverte-
brates are important to community
structure because they contribute signif-
icantly to a stream's total invertebrate
biomass (Morin and Nadon 1991,
Biological Community Characteristics
2-63
-------
Figure 2.33: Stream
biota. Food relation-
ships typically found
in streams.
microorganisms
(e.g., hyphomycete
fungi)
i «
4
course
particulate
organic
matter
light
larger plants
(mosses,
red algae)
flocculation
invertebrate
shredders
dissolved
organic
matter
fine
particulate
organic
matter
epilithic
algae
microorganisms
invertebrate
scrapers
Bourassa and Morin 1995). Further-
more, the larger species often play im-
portant roles in determining community
composition of other components of
the ecosystem. For example, herbivo-
rous feeding activities of caddisfly lar-
vae (Lamberti and Resh 1983), snails
(Steinman et al. 1987), and crayfish
(Lodge 1991) can have a significant
Table 2.12: Ranges of densities commonly
observed for selected groups of stream biota.
Biotic 1 Density
Component 1 (Individuals/Square Mile)
Algae
Bacteria
Protists
Microinvertebrates
Macroinvertebrates
Vertebrates
109-
1012-
108-
103-
104-
10«-
101°
1013
109
105
105
102
effect on the abundance and taxonomic
composition of algae and periphyton in
streams. Likewise, macroinvertebrate
predators, such as stoneflies, can influ-
ence the abundance of other species
within the invertebrate community
(Peckarsky 1985).
Collectively, microorganisms (fungi
and bacteria) and benthic invertebrates
facilitate the breakdown of organic ma-
terial, such as leaf litter, that enters the
stream from external sources. Some
invertebrates (insect larvae and am-
phipods) act as shredders whose feed-
ing activities break down larger organic
leaf litter to smaller particles. Other in-
vertebrates filter smaller organic mater-
ial from the water (blackfly larvae,
some mayfly nymphs, and some caddis-
fly larvae), scrape material off surfaces
2-64
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
(snails, limpets, and some caddisfly and
mayfly nymphs), or feed on material
deposited on the substrate (dipteran
larvae and some mayfly nymphs) (Moss
1988). These feeding activities result in
the breakdown of organic matter in ad-
dition to the elaboration of invertebrate
tissue, which other consumer groups,
such as fish, feed on.
Benthic macroinvertebrates, particularly
aquatic insect larvae and crustaceans,
are widely used as indicators of stream
health and condition. Many fish species
rely on benthic organisms as a food
source either by direct browsing on the
benthos or by catching benthic organ-
isms that become dislodged and drift
downstream (Walburg 1971).
Fish are ecologically important in
stream ecosystems because they are usu-
ally the largest vertebrates and often are
the apex predator in aquatic systems.
The numbers and species composition
of fishes in a given stream depends on
the geographic location, evolutionary
history, and such intrinsic factors as
physical habitat (current, depth, sub-
strates, riffle/pool ratio, wood snags,
and undercut banks), water quality
(temperature, dissolved oxygen, sus-
pended solids, nutrients, and toxic
chemicals), and biotic interactions (ex-
ploitation, predation, and competition).
There are approximately 700 native
freshwater species of fish in North
America (Briggs 1986). Fish species
richness is highest in the Mississippi
River Basin where most of the adaptive
radiations have occurred in the United
States (Allan 1995). In the Midwest, as
many as 50 to 100 species can occur in
a local area, although typically only half
the species native to a region may be
found at any one location (Horwitz
1978). Fish species richness generally
declines as one moves westward across
the United States, primarily due to ex-
tinction during and following the Pleis-
tocene Age (Fausch et al. 1984). For ex-
ample, 210 species are found west of the
Continental Divide, but only 40 of
these species are found on both sides of
the continent (Minckley and Douglas
1991). The relatively depauperate fauna
of the Western United States has been
attributed to the isolating mechanisms
of tectonic geology. Secondary biologi-
cal, physical, and chemical factors may
further reduce the species richness of a
specific community (Minckley and
Douglas 1991, Allan 1995).
Fish species assemblages in streams will
vary considerably from the headwaters
to the outlet due to changes in many
hydrologic and geomorphic factors
which control temperature, dissolved
oxygen, gradient, current velocity, and
substrate. Such factors combine to de-
termine the degree of habitat diversity
in a given stream segment. Fish species
richness tends to increase downstream
as gradient decreases and stream size
increases. Species richness is generally
lowest at small headwater streams due
to increased gradient and small stream
size, which increases the frequency and
severity of environmental fluctuations
(Hynes 1970, Matthews and Styron
1980). In addition, the high gradient
and decreased links with tributaries re-
duces the potential for colonization
and entry of new species.
Species richness increases in mid-order
to lower stream reaches due to in-
creased environmental stability, greater
numbers of potential habitats, and in-
creases in numbers of colonization
sources or links between major
drainages. As one proceeds down-
stream, pools and runs increase over rif-
fles, allowing for an increase in fine
bottom materials and facilitating the
growth of macrophytic vegetation.
These environments allow for the pres-
ence of fishes more tolerant of low oxy-
Biological Community Characteristics
2-65
-------
gen and increased temperatures. Fur-
ther, the range of body forms increases
with the appearance of those species
with less fusiform body shapes, which
are ecologically adapted to areas typi-
fied by decreased water velocities. In
higher order streams or large rivers the
bottom substrates often are typified by
finer sediments; thus herbivores, omni-
vores, and planktivores may increase in
response to the availability of aquatic
vegetation and plankton (Bond 1979).
Fish have evolved unique feeding and
reproductive strategies to survive in the
diverse habitat conditions of North
America. Horwitz (1978) examined the
structure of fish feeding guilds in 15
U.S. river systems and found that most
fish species (33 percent) were benthic
insectivores, whereas piscivores (16 per-
cent), herbivores (7 percent), omni-
vores (6 percent), planktivores (3
percent), and other guilds contained
fewer species. However, Allan (1995)
indicated that fish frequently change
feeding habits across habitats, life
stages, and season to adapt to changing
physical and biological conditions. Fish
in smaller headwater streams tend to be
insectivores or specialists, whereas the
number of generalists and the range of
feeding strategies increases downstream
in response to increasing diversity of
conditions.
Some fish species are migratory, return-
ing to a particular site over long dis-
tances to spawn. Others may exhibit
great endurance, migrating upstream
against currents and over obstacles such
as waterfalls. Many must move between
salt water and freshwater, requiring
great osmoregulatory ability (McKeown
1984). Species that return from the
ocean environment into freshwater
streams to spawn are called anadromous
species.
Species generally may be referred to as
cold water or warm water, and grada-
tions between, depending on their tem-
perature requirements (Magnuson et al.
1979). Fish such as salmonids are usu-
ally restricted to higher elevations or
northern climes typified by colder,
highly oxygenated water. These species
tend to be specialists, with rather nar-
row thermal tolerances and rather spe-
cific reproductive requirements. For
example, salmonids typically spawn by
depositing eggs over or within clean
gravels which remain oxygenated and
silt-free due to upwelling of currents
within the interstitial spaces. Reproduc-
tive movement and behavior is con-
trolled by subtle thermal changes
combined with increasing or decreasing
day-length. Salmonid populations,
therefore, are highly susceptible to
many forms of habitat degradation, in-
cluding alteration of flows, temperature,
and substrate quality.
Numerous fish species in the U.S. are
declining in number. Williams and
Julien (1989) presented a list of North
American fish species that the American
Fisheries Society believed should be
classified as endangered, threatened, or
of special concern. This list contains
364 fish species warranting protection
because of their rarity. Habitat loss was
the primary cause of depletion for ap-
proximately 90 percent of the species
listed. This study noted that 77 percent
of the fish species listed were found in
25 percent of the states, with the high-
est concentrations in eight southwestern
states. Nehlsen et al. (1991) provided a
list of 214 native naturally spawning
stocks of depleted Pacific salmon, steel-
head, and sea-run cutthroat stocks from
California, Oregon, Idaho, and Wash-
ington. Reasons cited for the declines
were alteration of fish passage and mi-
gration due to dams, flow reduction as-
sociated with hydropower and
2-66
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
agriculture, sedimentation and habitat
loss due to logging and agriculture,
overfishing, and negative interactions
with other fish, including nonnative
hatchery salmon and steelhead.
The widespread decline in the numbers
of native fish species has led to current
widespread interest in restoring the
quality and quantity of habitats for fish.
Restoration activities have frequently
centered on improving local habitats,
such as fencing or removing livestock
from streams, constructing fish pas-
sages, or installing instream physical
habitat. However, research has demon-
strated that in most of these cases the
success has been limited or question-
able because the focus was too narrow
and did not address restoration of the
diverse array of habitat requirements
and resources that are needed over the
life span of a species.
Stream corridor restoration practition-
ers and others are now acutely aware
that fish require many different habitats
over the season and lifespan to fulfill
needs for feeding, resting, avoiding
predators, and reproducing. For exam-
ple, Livingstone and Rabeni (1991) de-
termined that juvenile smallmouth bass
in the Jacks Fork River of southeastern
Missouri fed primarily on small
macroinvertebrates in littoral vegeta-
tion. Vegetation represented not only a
source of food but a refuge from preda-
tors and a warmer habitat, factors that
can collectively optimize chances for
survival and growth (Rabeni and Jacob-
son 1993). Adult smallmouth bass,
however, tended to occupy deeper pool
habitats, and the numbers and biomass
of adults at various sites were attributed
to these specific deep-water habitats
(McClendon and Rabeni 1987). Rabeni
and Jacobson (1993) suggested that an
understanding of these specific habitats,
combined with an understanding of the
fluvial hydraulics and geomorphology
that form and maintain them, are key
to developing successful stream restora-
tion initiatives.
The emphasis on fish community
restoration is increasing due to many
ecological, economic, and recreational
factors. In 1996 approximately 35 mil-
lion Americans older than 16 partic-
ipated in recreational fishing, resulting
in over $36 billion in expenditures
(Brouha 1997). Much of this activity is
in streams, which justifies stream corri-
dor restoration initiatives.
While fish stocks often receive the great-
est public attention, preservation of
other aquatic biota may also may be a
goal of stream restoration. Freshwater
mussels, many species of which are
threatened and endangered, are often of
particular concern. Mussels are highly
sensitive to habitat disturbances and
obviously benefit from intact, well-
managed stream corridors. The south-
central United States has the highest
diversity of mussels in the world. Mus-
sel ecology also is intimately linked
with fish ecology, as fish function as
hosts for mussel larvae (glochidia).
Among the major threats they face are
dams, which lead to direct habitat loss
and fragmentation of remaining habi-
tat, persistent sedimentation, pesticides,
and introduced exotic species, such as
fish and other mussel species.
Abiotic and Biotic Interrelations
in the Aquatic System
Much of the spatial and temporal vari-
ability of stream biota reflects variations
in both abiotic and biotic factors, in-
cluding water quality, temperature,
streamflow and flow velocity, substrate,
the availability of food and nutrients,
and predator-prey relationships. These
factors influence the growth, survival,
and reproduction of aquatic organisms.
While these factors are addressed indi-
Biological Community Characteristics
2-67
-------
vidually below, it is important to re-
member that they are often interdepen-
dent.
Flow Condition
The flow of water from upstream to
downstream distinguishes streams from
other ecosystems. The spatial and tem-
poral characteristics of streamflow, such
as fast versus slow, deep versus shallow,
turbulent versus smooth, and flooding
versus low flows, are described previ-
ously in this chapter. These flow charac-
teristics can affect both micro- and
macro-distribution patterns of numer-
ous stream species (Bayley and Li 1992,
Reynolds 1992, Ward 1992). Many or-
ganisms are sensitive to flow velocity
because it represents an important
mechanism for delivering food and nu-
trients yet also may limit the ability of
organisms to remain in a stream seg-
ment. Some organisms also respond to
temporal variations in flow, which can
change the physical structure of the
stream channel, as well as increase mor-
tality, modify available resources, and
disrupt interactions among species
(Resh et al. 1988, Bayley and Li 1992).
The flow velocity in streams determines
whether planktonic forms can develop
and sustain themselves. The slower the
currents in a stream, the more closely
the composition and configuration of
biota at the shore and on the bottom
approach those of standing water (Rut-
tner 1963). High flows are cues for tim-
ing migration and spawning of some
fishes. High flows also cleanse and sort
streambed materials and scour pools.
Extreme low flows may limit young fish
production because such flows often
occur during periods of recruitment and
growth (Kohler and Hubert 1993).
Water Temperature
Water temperature can vary markedly
within and among stream systems as a
function of ambient air temperature, al-
titude, latitude, origin of the water, and
solar radiation (Ward 1985, Sweeney
1993). Temperature governs many bio-
chemical and physiological processes in
cold-blooded aquatic organisms be-
cause their body temperature is the
same as the surrounding water; thus,
water temperature has an important
role in determining growth, develop-
ment, and behavioral patterns. Stream
insects, for example, often grow and de-
velop more rapidly in warmer portions
of a stream or during warmer seasons.
Where the thermal differences among
sites are significant (e.g., along latitudi-
nal or altitudinal gradients), it is possi-
ble for some species to complete two or
more generations per year at warmer
sites; these same species complete one
or fewer generations per year at cooler
sites (Sweeney 1984, Ward 1992).
Growth rates for algae and fish appear
to respond to temperature changes in a
similar fashion (Hynes 1970, Reynolds
1992). The relationships between tem-
perature and growth, development, and
behavior can be strong enough to affect
geographic ranges of some species
(Table 2.13).
Water temperature is one of the most
important factors determining the dis-
tribution of fish in freshwater streams,
due both to direct impacts and influ-
ence on dissolved oxygen concentra-
tions, and is influenced by local
conditions, such as shade, depth and
current. Many fish species can tolerate
only a limited temperature range. Such
fish as salmonids and sculpins domi-
nate in cold water streams, whereas
such species as largemouth bass, small-
mouth bass, suckers, minnows, sun-
fishes and catfishes may be present in
warmer streams (Walburg 1971).
Effects of Cover
For the purposes of restoration, land
use practices that remove overhead
2-68
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
Table 2.13: Maximum weekly average temperatures for growth and short term maximum
temperatures for selected fish (°F).
Source: Brungs and Jones 1977.
Species
Atlantic salmon
Bluegill
Brook trout
Common carp
Channel catfish
Largemouth bass
Rainbow trout
Smallmouth bass
Sockeye salmon
I Max. Weekly
Average Temp, for
Growth (Juveniles)
68°F
90°F
66°F
90°F
90°F
66°F
84°F
64°F
Max. Temp, for
Survival of Short
Exposure (Juveniles)
73°F
95°F
75°F
95°F
93°F
75°F
72°F
Max. Weekly
Average Temp.
for Spawning3
41°F
77°F
48°F
70°F
81°F
70°F
48°F
63°F
50°F
Max. Temp.
for Embryo
Spawning6
52°F
93°F
55°F
91°F
84°FC
81°FC
55°F
73°FC
55°F
a Optimum or mean of the range of spawning temperatures reported for the species.
b Upper temperature for successful incubation and hatching reported for the species.
c
Uppe
Upper temperature for spawning.
cover or decrease baseflows can increase
instream temperatures to levels that ex-
ceed critical thermal maxima for fishes
(Feminella and Matthews 1984). Thus,
maintenance or restoration of normal
temperature regimes can be an impor-
tant endpoint for stream managers.
Riparian vegetation is an important fac-
tor in the attenuation of light and tem-
perature in streams (Cole 1994). Direct
sunlight can significantly warm streams,
particularly during summer periods of
low flow. Under such conditions,
streams flowing through forests warm
rapidly as they enter deforested areas,
but may also cool somewhat when
streams reenter the forest. In Pennsylva-
nia (Lynch et al. 1980), average daily
stream temperatures that increased
12°C through a clearcut area were sub-
stantially moderated after flow through
1,640 feet of forest below the clearcut.
They attributed the temperature reduc-
tion primarily to inflows of cooler
ground water.
A lack of cover also affects stream tem-
perature during the winter. Sweeney
(1993) found that, while average daily
temperatures were higher in a second-
order meadow stream than in a compa-
rable wooded reach from April through
October, the reverse was true from No-
vember through March. In a review of
temperature effects on stream macroin-
vertebrates common to the Pennsylva-
nia Piedmont, Sweeney (1992) found
that temperature changes of 2 to 6 °C
usually altered key life-history charac-
teristics of the study species. Riparian
forest buffers have been shown to pre-
vent the disruption of natural tempera-
ture patterns as well as to mitigate the
increases in temperature following de-
forestation (Brown and Krygier 1970,
Brazier and Brown 1973).
The exact buffer width needed for tem-
perature control will vary from site to
site depending on such factors as
stream orientation, vegetation, and
width. Along a smaller, narrow headwa-
ter stream, the reestablishment of
shrubs, e.g., willows and alders, may
provide adequate shade and detritus to
restore both the riparian and aquatic
ecosystems. The planting and/or
reestablishment of large trees, e.g., cot-
tonwoods, willows, sycamores, ash, and
walnuts (Lowe 1964), along larger,
higher order rivers can improve the seg-
Biological Community Characteristics
2-69
-------
ment of the fishery closest to the banks,
but has little total effect on light and
temperature of wider rivers.
Heat budget models can accurately pre-
dict stream and river temperatures (e.g.,
Beschta 1984, Theurer et al. 1984).
Solar radiation is the major factor influ-
encing peak summer water tempera-
tures and shading is critical to the
overall temperature regime of streams
in small watersheds.
Dissolved Oxygen
Oxygen enters the water by absorption
directly from the atmosphere and by
plant photosynthesis (Mackenthun
1969). Due to the shallow depth, large
surface exposure to air and constant
motion, streams generally contain an
abundant dissolved oxygen supply even
when there is no oxygen production by
photosynthesis.
Dissolved oxygen at appropriate con-
centrations is essential not only to keep
aquatic organisms alive but to sustain
their reproduction, vigor, and develop-
ment. Organisms undergo stress at re-
duced oxygen levels that make them
less competitive in sustaining the
species (Mackenthun 1969). Dissolved
oxygen concentrations of 3.0 mg/L or
less have been shown to interfere with
fish populations for a number of rea-
sons (Mackenthun 1969, citing several
other sources) (Table 2.14).
Depletion of dissolved oxygen can re-
sult in the death of aquatic organisms,
including fish. Fish die when the de-
mand for oxygen by biological and
chemical processes exceeds the oxygen
input by reaeration and photosynthesis,
resulting in fish suffocation. Oxygen de-
pletion usually is associated with slow
current, high temperature, extensive
growth of rooted aquatic plants, algal
blooms, or high concentrations of or-
ganic matter (Needham 1969).
Stream communities are susceptible to
pollution that reduces the dissolved
oxygen supply (Odum 1971). Major
factors determining the amount of oxy-
gen found in water are temperature,
pressure, abundance of aquatic plants
and the amount of natural aeration
from contact with the atmosphere
(Needham 1969). A level of 5 mg/L of
Table 2.14: Summary of dissolved oxygen concentrations (mg/L) generally associated with effects
on fish in salmonid and nonsalmonid waters.
Source: USEPA 1987.
Level of Effect
Early life stages (eggs and fry)
No production impairment
Slight production impairment
Moderate production impairment
Severe production impairment
Limit to avoid acute mortality
Other life stage
No production impairment
Slight production impairment
Moderate production impairment
Severe production impairment
Limit to avoid acute mortality
Salmonid3
11(8)
9(6)
8(5)
7(4)
6(3)
8(0)
6(0)
5(0)
4(0)
3(0)
Nonsalmonid
6.5
5.5
5.0
4.5
4.0
H
6.0
5.0
4.0
3.5
3.0
3 Values for salmonid early life stages are water column concentrations recommended to achieve the required concentration of dissolved oxygen
in the gravel spawning substrate (shown in parentheses).
2-70
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
dissolved oxygen in water is associated
with normal activity of most fish (Wai-
burg 1971). Oxygen analyses of good
trout streams show dissolved oxygen
concentrations that range from 4.5 to
9.5 mg/L (Needham 1969).
PH
Aquatic organisms from a wide range of
taxa exist and thrive in aquatic systems
with nearly neutral hydrogen ion activ-
ity (pH 7). Deviations, either toward a
more basic or acidic environment, in-
crease chronic stress levels and eventu-
ally decrease species diversity and
abundance (Figure 2.34). One of the
more widely recognized impacts of
changes in pH has been attributed to
increased acidity of rainfall in some
parts of the United States, especially
areas downwind of industrial and
urban emissions (Schreiber 1995). Of
particular concern are environments
that have a reduced capacity to neutral-
ize acid inputs because soils have a lim-
ited buffering capacity. Acidic rainfall
can be especially harmful to environ-
ments such as the Adirondack region of
upstate New York, where runoff already
tends to be slightly acidic as a result of
natural conditions.
Substrate
Stream biota respond to the many abi-
otic and biotic variables influenced by
substrate. For example, differences in
Figure 2.34: Effects of acid rain on some aquatic species. As acidity increases (and pH decreases) in
lakes and streams, some species are lost.
Rainbow trout
(Oncorhyncus mykiss)
Brown trout
(Salmo trutta)
*embryonic life stage
selected species
Brook trout
(Salvelinus fontinalus)
Smallmouth bass
(Micropterus dolomieu)
Flathead minnow
(Pimephalus promelas)
Pumpkinseed sunfish
(Lepomis gibbosus)
Yellow perch
(Perca flavescens)
Bullfrog*
(Rana catesbeiana)
Wood frog*
(R. sylvatica)
American toad*
(Bufo americanus)
Spotted salamander*
(Ambystoma maculatum)
Clam**
Crayfish**
Snail**
Mayfly*
PH
Biological Community Characteristics
2-71
-------
species composition and abundance
can be observed among macroinverte-
brate assemblages found in snags, sand,
bedrock, and cobble within a single
stream reach (Benke et al. 1984, Smock
et al. 1985, Huryn and Wallace 1987).
This preference for conditions associ-
ated with different substrates con-
tributes to patterns observed at larger
spatial scales where different macroin-
vertebrate assemblages are found in
coastal, piedmont, and mountain
streams (Hackney et al. 1992).
Stream substrates can be viewed in the
same functional capacity as soils in the
terrestrial system; that is, stream sub-
strates constitute the interface between
water and the hyporheic subsurface of
the aquatic system. The hyphorheic zone
is the area of substrate which lies below
the substrate/water interface, and may
range from a layer extending only
inches beneath and laterally from the
stream channel, to a very large subsur-
face environment. Alluvial floodplains
of the Flathead River, Montana, have a
hyphorheic zone with significant sur-
face water/ground water interaction
which is 2 miles wide and 33 feet deep
(Stanford and Ward 1988). Naiman et
al. (1994) discussed the extent and con-
nectivity of hyphorheic zones around
streams in the Pacific Northwest. They
hypothesized that as one moves from
low-order (small) streams to high-order
(large) streams, the degree of hy-
phorheic importance and continuity
first increases and then decreases. In
small streams, the hyphorheic zone is
limited to small floodplains, meadows,
and stream segments where coarse sedi-
ments are deposited over bedrock. The
hyphorheic zones are generally not con-
tinuous. In mid-order channels with
more extensive floodplains, the spatial
connectivity of the hyphorheic zone in-
creases. In large order streams, the spa-
tial extent of the hyphorheic zone is
usually greatest, but it tends to be
highly discontinuous because of fea-
tures associated with fluvial activities
such as oxbow lakes and cutoff chan-
nels, and because of complex interac-
tions of local, intermediate, and
regional ground water systems (Naiman
etal. 1994) (Figure 2.35).
Stream substrates are composed of vari-
ous materials, including clay, sand,
gravel, cobbles, boulders, organic mat-
ter, and woody debris. Substrates form
solid structures that modify surface and
interstitial flow patterns, influence the
accumulation of organic materials, and
provide for production, decomposition,
and other processes (Minshall 1984).
Sand and silt are generally the least
favorable substrates for supporting
aquatic organisms and support the
fewest species and individuals. Flat or
rubble substrates have the highest den-
sities and the most organisms (Odum
1971). As previously described, sub-
strate size, heterogeneity, stability with
respect to high and baseflow, and dura-
bility vary within streams, depending
on particle size, density, and kinetic en-
ergy of flow. Inorganic substrates tend
to be larger upstream than downstream
and tend to be larger in riffles than in
pools (Leopold et al. 1964). Likewise,
the distribution and role of woody de-
bris varies with stream size (Maser and
Sedell 1994).
In forested watersheds, and in streams
with significant areas of trees in their ri-
parian corridor, large woody debris that
falls into the stream can increase the
quantity and diversity of substrate and
aquatic habitat or range (Bisson et al.
1987, Dolloff et al. 1994). Debris dams
trap sediment behind them and often
create scour holes immediately down-
stream. Eroded banks commonly occur
at the boundaries of debris blockages.
2-72
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
Organic Material
Metabolic activity within a stream reach
depends on autochthonous, allochtho-
nous, and upstream sources of food and
nutrients (Minshall et al. 1985). Au-
tochthonous materials, such as algae
and aquatic macrophytes, originate
within the stream channel, whereas al-
lochthonous materials such as wood,
leaves, and dissolved organic carbon,
originate outside the stream channel.
Upstream materials may be of au-
tochthonous or allochthonous origin
and are transported by streamflow to
downstream locations. Seasonal flood-
ing provides allochthonous input of or-
ganic material to the stream channel and
also can significantly increase the rate of
decomposition of organic material.
The role of primary productivity of
streams can vary depending on geo-
graphic location, stream size, and sea-
son (Odum 1957, Minshall 1978). The
river continuum concept (Vannote et al.
1980) (see The River Continuum Concept
in section l.E in Chapter 1) hypothe-
sizes that primary productivity is of
minimal importance in shaded head-
water streams but increases in signifi-
cance as stream size increases and
riparian vegetation no longer limits the
entry of light to stream periphyton. Nu-
merous researchers have demonstrated
that primary productivity is of greater
importance in certain ecosystems, in-
cluding streams in grassland and desert
ecosystems. Flora of streams can range
from diatoms in high mountain streams
to dense stands of macrophytes in low
gradient streams of the Southeast.
As discussed in Section 2.C, loading of
nitrogen and phosphorus to a stream
can increase the rate of algae and
aquatic plant growth, a process known
as eutrophication. Decomposition of this
excess organic matter can deplete oxy-
water
table
Figure 2.35: Hyphorheic zone. Summary of the
different means of migration undergone by
members of the stream benthic community.
gen reserves and result in fish kills and
other aesthetic problems in waterbodies.
Eutrophication in lakes and reservoirs is
indirectly measured as standing crops
of phytoplankton biomass, usually rep-
resented by planktonic chlorophyll a
concentration. However, phytoplankton
biomass is usually not the dominant
portion of plant biomass in smaller
streams, due to periods of energetic
flow and high substrate to volume ra-
tios that favor the development of peri-
phyton and macrophytes on the stream
bottom. Stream eutrophication can re-
sult in excessive algal mats and oxygen
depletion at times of decreased flows
and higher temperatures (Figure 2.36).
Furthermore, excessive plant growth can
occur in streams at apparently low am-
bient concentrations of nitrogen and
phosphorus because the stream currents
promote efficient exchange of nutrients
and metabolic wastes at the plant cell
surface.
impermeable
layer
Biological Community Characteristics
2-73
-------
Figure 2.36: Stream eutrophication.
Eutrophication can result in oxygen depletion.
In many streams, shading or turbidity
limit the light available for algal
growth, and biota depend highly on
allochthonous organic matter, such as
leaves and twigs produced in the sur-
rounding watershed. Once leaves or
other allochthonous materials enter the
stream, they undergo rapid changes
(Cummins 1974). Soluble organic com-
pounds, such as sugars, are removed via
leaching. Bacteria and fungi subse-
quently colonize the leaf materials and
metabolize them as a source of carbon.
The presence of the microbial biomass
increases the protein content of the
leaves, which ultimately represents a
high quality food resource for shred-
ding invertebrates.
The combination of microbial decom-
position and invertebrate shredding/
scraping reduces the average particle
size of the organic matter, resulting in
the loss of carbon both as respired CO2
and as smaller organic particles trans-
ported downstream. These finer parti-
cles, lost from one stream segment,
become the energy inputs to the down-
stream portions of the stream. This uni-
directional movement of nutrients and
organic matter in lotic systems is
slowed by the temporary retention,
storage, and utilization of nutrients in
leaf packs, accumulated debris, inverte-
brates, and algae.
Organic matter processing has been
shown to have nutrient-dependent rela-
tionships similar to primary productiv-
ity. Decomposition of leaves and other
forms of organic matter can be limited
by either nitrogen or phosphorus, with
predictive N:P ratios being similar to
those for growth of algae and periphy-
ton. Leaf decomposition occurs by a
sequential combination of microbial
decomposition, invertebrate shredding,
and physical fractionation. Leaves and
organic matter itself are generally low
in protein value. However, the coloniza-
tion of organic matter by bacteria and
fungi increases the net content of nitro-
gen and phosphorus due to the accu-
mulation of proteins and lipids
contained in microbial biomass. These
compounds are a major nutritive source
for aquatic invertebrates. Decaying or-
ganic matter represents a major storage
component for nutrients in streams, as
well as a primary pathway of energy
and nutrient transfer within the food
web. Ultimately, the efficiency of reten-
tion and utilization is reflected at the
top of the food web in the form of fish
biomass.
Organisms often respond to variations
in the availability of autochthonous, al-
lochthonous, and upstream sources. For
example, herbivores are relatively more
common in streams having open ripar-
ian canopies and high algal productiv-
ity compared to streams having closed
canopies and accumulated leaves as the
primary food resource (Minshall et al.
1983). Similar patterns can be observed
longitudinally within the same stream
(Behmer and Hawkins 1986).
2-74
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
Terrestrial and Aquatic
Ecosystem Components for
Stream Corridor Restoration
The previous sections presented the bio-
logical components and functional
processes that shape stream corridors.
The terrestrial and aquatic environ-
ments were discussed separately for the
sake of simplicity and ease of under-
standing. Unfortunately, this is fre-
quently the same approach taken in
environmental restoration initiatives,
with efforts placed separately on the
uplands, riparian area, or instream
channel. The stream corridor must be
viewed as a single functioning unit or
ecosystem with numerous connections
and interactions between components.
Successful stream corridor restoration
cannot ignore these fundamental rela-
tionships.
The structure and functions of vegeta-
tion are interrelated at all scales. They
are also directly tied to ecosystem dy-
namics. Particular vegetation types may
have characteristic regeneration strate-
gies (e.g., fire, treefall gaps) that main-
tain those types within the landscape at
all times. Similarly, certain topographic
settings may be more likely than others
to be subject to periodic, dramatic
changes in hydrology and related vege-
tation structure as a result of massive
debris jams or occupation by beavers.
However, in the context of stream corri-
dor ecosystems, some of the most fun-
damental dynamic interactions relate to
stream flooding and channel migration.
Many ecosystem functions are influ-
enced by the structural characteristics of
vegetation. In an undeveloped water-
shed, the movement of water and other
materials is moderated by vegetation
and detritus, and nutrients are mobi-
lized and conserved in complex pat-
terns that generally result in balanced
interactions between terrestrial and
aquatic systems. As the character and
distribution of vegetation is altered by
removal of biomass, agriculture, live-
stock grazing, development, and other
land uses, and the flow patterns of
water, sediment, and nutrients are mod-
ified, the interactions among system
components become less efficient and
effective. These problems can become
more pronounced when they are aggra-
vated by introductions of excess nutri-
ents and synthetic toxins, soil
disturbances, and similar impacts.
Stream migration and flooding are
principal sources of structural and
compositional variation within and
among plant communities in most
undisturbed floodplains (Brinson et al.
1981). Although streams exert a com-
plex influence on plant communities,
vegetation directly affects the integrity
and characteristics of stream systems.
For example, root systems bind bank
sediments and moderate erosion
processes, and floodplain vegetation
slows overbank flows, inducing sedi-
ment deposition. Trees and smaller
woody debris that fall into the channel
deflect flows, inducing erosion at some
points and deposition at others, alter
pool distribution, the transport of or-
ganic material, as well as a number of
other processes. The stabilization of
streams that are highly interactive with
their floodplains can disrupt the funda-
mental processes controlling the struc-
ture and function of stream corridor
ecosystems, thereby indirectly affecting
the characteristics of the surrounding
landscape.
In most instances, the functions of veg-
etation that are most apparent are those
that influence fish and wildlife. At the
landscape level, the fragmentation of
native cover types has been shown to
significantly influence wildlife, often fa-
voring opportunistic species over those
requiring large blocks of contiguous
Biological Community Characteristics
2-75
-------
habitat. In some systems, relatively
small breaks in corridor continuity can
have significant impacts on animal
movement or on the suitability of
stream conditions to support certain
aquatic species. In others, establishment
of corridors that are structurally differ-
ent from native systems or inappropri-
ately configured can be equally
disruptive. Narrow corridors that are es-
sentially edge habitat may encourage
generalist species, nest parasites, and
predators, and where corridors have
been established across historic barriers
to animal movement, they can disrupt
the integrity of regional animal assem-
blages (Knopf etal. 1988).
Some riparian dependent species are
linked to streamside riparian areas with
fairly contiguous dense tree canopies.
Without new trees coming into the
population, older trees creating this
linked canopy eventually drop out, cre-
ating ever smaller patches of habitat.
Restoration that influences tree stands
so that sufficient recruitment and patch
size can be attained will benefit these
species. For similar reasons, many ripar-
ian-related raptors such as the common
black-hawk (Buteogallus anthracinus),
gray hawk (Buteo nitidus), bald eagle
(Haliaeetus leucocephalus), Cactus ferrug-
inous pygmy-owl (Glaucidium brasil-
ianum cactorum), and Cooper's hawk
(Accipiter cooperii], depend upon various
sizes and shapes of woody riparian trees
for nesting substrate and roosts.
Restoration practices that attain suffi-
cient tree recruitment will greatly bene-
fit these species in the long term, and
other species in the short term.
Some aspects related to this subject
have been discussed as ecosystem com-
ponents and functions under other sec-
tions. Findings from the earliest studies
of the impacts of fragmentation of ri-
parian habitats on breeding birds were
published for the Southwest (Carothers
and Johnson 1971, Johnson 1971,
Carothers et al. 1974). Subsequent
studies by other investigators found
similar results. Basically, cottonwood-
willow gallery forests of the North
American Southwest supported the
highest concentrations of noncolonial
nesting birds for North America. De-
struction and fragmentation of these ri-
parian forests reduced species richness
and resulted in a nearly straight-line re-
lationship between numbers of nesting
pairs/acre and number of mature
trees/acre. Later studies demonstrated
that riparian areas are equally impor-
tant as conduits for migrating birds
(Johnson and Simpson 1971, Stevens et
al. 1977).
When considering restoration of ripar-
ian habitats, the condition of adjacent
habitats must be considered. Carothers
(1979) found that riparian ecosystems,
especially the edges, are widely used by
nonriparian birds. In addition he found
that some riparian birds utilized adja-
cent nonriparian ecosystems. Carothers
et al. (1974) found that smaller breed-
ing species [e.g., warblers and the West-
ern wood pewee (Contopus sordidulus)]
tended to carry on all activities within
the riparian ecosystem during the
breeding season. However, larger
species (e.g., kingbirds and doves) com-
monly foraged outside the riparian
ecosystem in adjacent habitats. Larger
species (e.g., raptors) may forage miles
from riparian ecosystems, but still de-
pend on them in critical ways (Lee et al.
1989).
Because of more mesic conditions cre-
ated by the canyon effect, canyons and
their attendant riparian vegetation serve
as corridors for short-range movements
of animals along elevational gradients
(e.g., between summer and winter
ranges). Long-range movements that
occur along riparian zones throughout
North America include migration of
2-76
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
birds and bats. Riparian zones also
serve as stopover habitat for migrating
birds (Stevens et al. 1977). Woody vege-
tation is generally important, not only
to most riparian ecosystems, but also to
adjacent aquatic and even upland
ecosystems. However, it is important to
establish clear management objectives
before attempting habitat modification.
Restoring all of a given ecosystem to its
"pristine condition" may be impossible,
especially if upstream conditions have
been heavily modified, such as by a
dam or other water diversion project.
Even if complete restoration is a possi-
bility, it may not accomplish or com-
plement the restoration goals.
For example, encroachment of woody
vegetation in the channel below several
dams in the Platte River Valley in Ne-
braska has greatly decreased the
amount of important wet meadow
habitat. This area has been declared
critical habitat for the whooping crane
(Cms americana) (Aronson and Ellis
1979), for piping plover, and for the in-
terior least tern. It is also an important
staging area for up to 500,000 sandhill
cranes (Grus canadensis) from late Feb-
ruary to late April and supports 150 to
250 bald eagles (Haliaeetus
leucocephalus). Numerous other impor-
tant species using the area include the
peregrine falcon (Falco peregrinus),
Canada goose (Branta canadensis), mal-
lard (Anas platyrhynchos), numerous
other waterfowl, and raptors (USFWS
1981). Thus, managers here are con-
fronted with means of reducing riparian
groves in favor of wet meadows.
Biological Community Characteristics
2-77
-------
2.E Functions and Dynamic Equilibrium
Throughout the past two chapters, this
document has covered stream corridor
structure and the physical, chemical,
and biological processes occurring in
stream corridors. This information
shows how stream corridors function as
ecosystems, and consequently, how
these characteristic structural features
and processes must be understood in
order to enable stream corridor func-
tions to be effectively restored. In fact,
reestablishing structure or restoring a
particular physical or biological process
is not the only thing that restoration
seeks to achieve. Restoration aims to
reestablish valued functions. Focusing
on ecological functions gives the
restoration effort its best chance to
recreate a self-sustaining system. This
property of sustainability is what sepa-
rates a functionally sound stream, that
freely provides its many benefits to peo-
ple and the natural environment, from
an impaired watercourse that cannot
sustain its valued functions and may re-
main a costly, long-term maintenance
burden.
Section 1 .A of Chapter 1 emphasized
matrix, patch, corridor and mosaic as
the most basic building blocks of physi-
cal structure at local to regional scales.
Ecological functions, too, can be sum-
marized as a set of basic, common
themes that recur in an infinite variety
of settings. These six critical functions
are habitat, conduit, filter, barrier, source,
and sink (Figure 2.37).
In this section, the processes and struc-
tural descriptions of the past two chap-
ters are revisited in terms of these
critical ecological functions.
Two attributes are particularly impor-
tant to the operation of stream corridor
functions:
Habitatthe spatial
structure of the envi-
ronment which allows
species to live, repro-
duce, feed, and move.
Barrierthe stoppage
of materials, energy,
and organisms.
Conduitthe ability of
the system to transport
materials, energy, and
organisms.
Filterthe selective
penetration of materi-
als, energy, and organ-
isms.
Sourcea setting
where the output of
materials, energy, and
organisms exceeds
input.
Sinka setting where
the input of water,
energy, organisms
and materials exceeds
output.
Habitat
Barrier
Conduit
Filter
Source
Sink
Figure 2.37: Critical ecosystem functions. Six
functions can be summarized as a set of basic,
common themes recurring in a variety of settings.
2-78
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
ConnectivityThis is a measure of
how spatially continuous a corridor
or a matrix is (Forman and Godron
1986). This attribute is affected by
gaps or breaks in the corridor and
between the corridor and adjacent
land uses (Figure 2.38). A stream
corridor with a high degree of con-
nectivity among its natural commu-
nities promotes valuable functions
including transport of materials and
energy and movement of flora and
fauna.
WidthIn stream corridors, this refers
to the distance across the stream and
its zone of adjacent vegetation cover.
Factors affecting width are edges,
community composition, environ-
mental gradients, and disturbance
effects of adjacent ecosystems,
including those with human activity.
Example measures of width include
average dimension and variance,
number of narrows, and varying
habitat requirements (Dramstad et
al. 1996).
Width and connectivity interact
throughout the length of a stream corri-
dor. Corridor width varies along the
length of the stream and may have
gaps. Gaps across the corridor interrupt
and reduce connectivity. Evaluating
connectivity and width can provide
some of the most valuable insight for
designing restoration actions that miti-
gate disturbances.
The following subsections discuss each
of the functions and general relation-
ship to connectivity and width. The
final subsection discusses dynamic
equilibrium and its relevance to stream
corridor restoration.
Figure 2.38: Landscapes with (A) high and (B) low degrees of connectivity. A connected landscape
structure generally has higher levels of functions than a fragmented landscape.
Functions and Dynamic Equilibrium
2-79
-------
Habitat Functions
Habitat is a term used to describe an
area where plants or animals (including
people) normally live, grow, feed, re-
produce, and otherwise exist for any
portion of their life cycle. Habitats pro-
vide organisms or communities of or-
ganisms with the necessary elements of
life, such as space, food, water, and
shelter.
Under suitable conditions often pro-
vided by stream corridors, many species
can use the corridor to live, find food
and water, reproduce, and establish vi-
able populations. Some measures of a
stable biological community are popu-
lation size, number of species, and ge-
netic variation, which fluctuate within
expected limits over time. To varying
degrees, stream corridors constructively
influence these measures. The corridor's
value as habitat is increased by the fact
that corridors often connect many small
habitat patches and thereby create
larger, more complex habitats with
larger wildlife populations and higher
biodiversity.
Habitat functions differ at various
scales, and an appreciation of the scales
at which different habitat functions
occur will help a restoration initiative
succeed. The evaluation of habitat at
larger scales, for example, may make
note of a biotic community's size, com-
position, connectivity, and shape.
At the landscape scale, the concepts of
matrix, patches, mosaics and corridors
are often involved in describing habitat
over large areas. Stream corridors and
major river valleys together can provide
substantial habitat. North American fly-
ways include examples of stream and
river corridor habitat exploited by mi-
gratory birds at landscape to regional
scales.
Stream corridors, and other types of
naturally vegetated corridors as well,
can provide migrating forest and ripar-
ian species with their preferred resting
and feeding habitats during migration
stopovers. Large mammals such as
black bear are known to require large,
contiguous wild terrain as home range,
and in many parts of the country broad
stream corridors are crucial to linking
smaller patches into sufficiently large
territories.
Habitat functions within watersheds
may be examined from a somewhat dif-
ferent perspective. Habitat types and
patterns within the watershed are signif-
icant, as are patterns of connectivity to
adjoining watersheds. The vegetation of
the stream corridor in upper reaches of
watersheds sometimes has become dis-
connected from that of adjacent water-
sheds and corridors beyond the divide.
When terrestrial or semiaquatic stream
corridor communities are connected at
their headwaters, these connections will
usually help provide suitable alternative
habitats beyond the watershed.
Assessing habitat function at the stream
corridor and smaller scales can also be
viewed in terms of patches and corri-
dors, but in finer detail than in land-
scapes and watersheds. It is also at local
scales that transitions among the vari-
ous habitats within the corridor can be-
come more important. Stream corridors
often include two general types of habi-
tat structure: interior and edge habitat.
Habitat diversity is increased by a corri-
dor that includes both edge and interior
conditions, although for most streams,
corridor width is insufficient to provide
2-80
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
Edge and Interior Habitat
Two important habitat characteristics are edges
and interior (Figure 2.39) Edges are critical lines of
interaction between different ecosystems. Interior
habitats are generally more stable, sheltered envi-
ronments where the ecosystem may remain rela-
tively the same for prolonged periods. Edge habi-
tat is exposed to highly variable environmental gra-
dients. The result is a different species composition
and abundance than observed interior habitat.
Edges are important as filters of disturbance to
interior habitat. Edges can also be diverse areas
with a large variety of flora and fauna.
Edges and interiors are scale-independent concepts.
Larger mammals known as interior forest species
may need to be miles from the forest edge to find
desired habitat, while an insect or amphibian may
be sensitive to the edges and interiors of the micro-
habitat under a rotted log. The edges and interiors
of a stream corridor, therefore, depend upon the
species being considered. As elongated, narrow
ecosystems that include land/water interfaces and
often include natural/human-made boundaries as
well at the upland fringe, stream corridors have an
abundance of edges and these have a pronounced
effect on their biota.
Edges and interiors are each preferred by different
sets of plant and animal species, and it is inappro-
priate to consider edges or interiors as consistently
"bad" or "good" habitat characteristics. It may be
desirable to maintain or increase edge in some
circumstances, or favor interior habitats in others.
Generally speaking, however, human activity tends
to increase edge and decrease interior, so more
often it is restoring or protecting interior that
merits specific management action.
Edge habitat at the stream corridor boundary typi-
cally has higher inputs of solar energy, precipita-
tion, wind energy, and other influences from the
adjacent ecosystems. The difference in environ-
mental gradients at the stream corridor's edge
results in a diversified plant and animal community
interacting with adjacent ecosystems. The effect of
edge is more pronounced when the amount of
interior habitat is minimal.
Interior habitat occurs further from the perimeter
of the element. Interior is typified by more stable
environmental inputs than those found at the
edge of an ecosystem. Sunlight, rainfall, and wind
effects are less intense in the interior. Many sensi-
tive or rare species depend upon a less-disturbed
environment for their survival. They are therefore
tolerant of only "interior" habitat conditions. The
distance from the perimeter required to create
these interior conditions is dependent upon the
species' requirements.
Interior plants and animals differ considerably from
those that prefer or tolerate the edge's variability.
With an abundance of edge, stream corridors
often have mostly edge species. Because large
ecosystems and wide corridors are becoming
increasingly fragmented in modern landscapes,
however, interior species are often rare and hence
are targets for restoration. The habitat require-
ments of interior species (with respect to distance
from edge are a useful guide in restoring larger
stream corridors to provide a diversity of habitat
types and sustainable communities.
Figure 2.39: Edge and interior habitat of a woodlot.
Interior plants and animals differ considerably from
those that prefer or tolerate the edge's variability.
Natural Disturbances
2-81
-------
much interior habitat for larger verte-
brates such as forest interior bird
species. For this reason, increasing inte-
rior habitat is sometimes a watershed
scale restoration objective.
Habitat functions at the corridor scale
are strongly influenced by connectivity
and width. Greater connectivity and in-
creased width along and across a stream
corridor generally increases its value as
habitat. Stream valley morphology and
environmental gradients (such as grad-
ual changes in soil wetness, solar radia-
tion, and precipitation) can cause
changes in plant and animal communi-
ties. More species generally find suitable
habitat conditions in a wide, contigu-
ous, and diverse assortment of native
plant communities within the stream
corridor than in a narrow, homoge-
neous or highly fragmented corridor.
When applied strictly to stream chan-
nels, however, this might not be true.
Some narrow and deeply incised
streams, for example, provide thermal
conditions that are critical for endan-
gered salmonids.
Habitat conditions within a corridor
vary according to factors such as climate
and microclimate, elevation, topogra-
phy, soils, hydrology, vegetation, and
human uses. In terms of planning
restoration measures, corridor width is
especially important for wildlife. When
planning for maintenance of a given
wildlife species, for example, the dimen-
sion and shape of the corridor must be
wide enough to include enough suit-
able habitat that this species can popu-
late the stream corridor. Corridors that
are too narrow may provide as much of
a barrier to some species' movement as
would a complete gap in the corridor.
On local scales, large woody debris that
becomes lodged in the stream channel
can create morphological changes to
the stream and adjacent streambanks.
Pools may be formed downstream from
a log that has fallen across a stream and
both upstream and downstream flow
characteristics are altered. The structure
formed by large woody debris in a
stream improves aquatic habitat for
most fish and invertebrate species.
Riparian forests, in addition to their
edge and interior habitats, may offer
vertical habitat diversity in their canopy,
subcanopy, shrub and herb layers. And
within the channel itself, riffles, pools,
glides, rapids and backwaters all pro-
vide different habitat conditions in
both the water column and the
streambed. These examples, all de-
scribed in terms of physical structure,
illustrate once again the strong linkage
between structure and habitat function.
Conduit Function
The conduit function is the ability to
serve as a flow pathway for energy, ma-
terials, and organisms. A stream corri-
dor is above all a conduit that was
formed by and for collecting and trans-
porting water and sediment. In addi-
tion, many other types of materials and
biota move throughout the system.
The stream corridor can function as a
conduit laterally, as well as longitudi-
nally, with movement by organisms and
materials in any number of directions.
Materials or animals may further move
across the stream corridor, from one
side to another. Birds or small mam-
mals, for example, may cross a stream
with a closed canopy by moving
through its vegetation. Organic debris
and nutrients may fall from higher to
2-82
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
lower floodplains and into the stream
within corridors, affecting the food sup-
ply for stream invertebrates and fishes.
Moving material is important because it
impacts the hydrology, habitat, and
structure of the stream as well as the ter-
restrial habitat and connections in the
floodplain and uplands. The structural
attributes of connectivity and width also
influence the conduit function.
For migratory or highly mobile wildlife,
corridors serve as habitat and conduit
simultaneously. Corridors in combina-
tion with other suitable habitats, for ex-
ample, make it possible for songbirds
to move from wintering habitat in the
neo-tropics to northern, summer habi-
tats. Many species of birds can only fly
for limited distances before they must
rest and refuel. For stream corridors to
function effectively as conduits for these
birds, they must be sufficiently con-
nected and be wide enough to provide
required migratory habitat.
Stream corridors are also conduits for
the movement of energy, which occurs
in many forms. The gravity-driven en-
ergy of stream flow continually sculpts
and modifies the landscape. The corri-
dor modifies heat and energy from sun-
light as it remains cooler in spring and
summer and warmer in the fall. Stream
valleys are effective airsheds, moving
cool air from higher to lower elevations
in the evening. The highly productive
plant communities of a corridor accu-
mulate energy as living plant material,
and export large amounts in the form
of leaf fall or detritus. The high levels
of primary productivity, nutrient flow,
and leaf litter fall also fuel increased
decomposition in the corridor, allow-
ing new transformations of energy and
materials. At its outlet, a stream's out-
puts to the next larger water body (e.g.,
increased water volume, higher temper-
ature, sediments, nutrients, and organ-
isms) are in part the excesses of energy
from its own system.
One of the best known and studied ex-
amples of aquatic species movement
and interaction with the watershed is
the migration of salmon upstream for
spawning. After maturing in the ocean,
the fish are dependent on access to
their upstream spawning grounds. In
the case of Pacific salmon species, the
stream corridor is dependent upon the
resultant biomass and nutrient input of
abundant spawning and dying adults
into the upper reaches of stream sys-
tems during spawning. Thus, connectiv-
ity is often critical for aquatic species
transport, and in turn, nutrient trans-
port upstream from ocean waters to
stream headwaters.
Streams are also conduits for distribu-
tion of plants and their establishment
in new areas (Malanson 1993). Flowing
water may transport and deposit seeds
over considerable distances. In flood
stage, mature plants may be uprooted,
relocated, and redeposited alive in new
locations. Wildlife also help redistribute
plants by ingesting and transporting
seeds throughout different parts of the
corridor.
Sediment (bed load or suspended load)
is also transported through the stream.
Alluvial streams are dependent on the
continual supply and transport of sedi-
ment, but many of their fish and inver-
tebrates can also be harmed by too
much fine sediment. When conditions
are altered, a stream may become either
starved of sediment or choked with sed-
iment down-gradient. Streams lacking
appropriate amounts of sediment at-
tempt to reestablish equilibrium through
downcutting, bank erosion, and channel
erosion. An appropriately structured
stream corridor will optimize timing
and supply of sediment to the stream to
improve sediment transport functions.
Functions and Dynamic Equilibrium
2-83
-------
Local areas in the corridor are depen-
dent on the flow of materials from one
point to another. In the salmonid ex-
ample, the local upland area adjacent to
spawning grounds is dependent upon
the nutrient transfer from the biomass
of the fish into other terrestrial wildlife
and off into the uplands. The local
structure of the streambed and aquatic
ecosystem are dependent upon the sedi-
ment and woody material from up-
stream and upslope to create a
self-regulating and stable channel.
Stream corridor width is important
where the upland is frequently a sup-
plier of much of the natural load of
sediment and biomass into the stream.
A wide, contiguous corridor acts as a
large conduit, allowing flow laterally
and longitudinally along the corridor.
Conduit functions are often more lim-
ited in narrow or fragmented corridors.
Filter and Barrier Functions
Stream corridors may serve as barriers
that prevent movement or filters that
allow selective penetration of energy,
materials and organisms. In many ways,
the entire stream corridor serves benefi-
cially as a filter or barrier that reduces
water pollution, 2-83minimizes sedi-
ment transport, and often provides a
natural boundary to land uses, plant
communities, and some less mobile
wildlife species.
Materials, energy, and organisms which
moved into and through the stream cor-
ridor may be filtered by structural attrib-
utes of the corridor. Attributes affecting
barrier and filter functions include con-
nectivity (gap frequency) and corridor
width (Figure 2.40). Elements which
i are moving along a stream corridor edge
may also be selectively filtered as they
enter the stream corridor. In these cir-
cumstances it is the shape of the edge,
whether it is straight or convoluted,
which has the greatest effect on filtering
functions. Still, it is most often move-
ment perpendicular to the stream corri-
dor which is most effectively filtered or
halted.
Materials may be transported, filtered,
or stopped altogether depending upon
the width and connectedness of a
stream corridor. Material movement
across landscapes toward large river val-
leys may be intercepted and filtered by
stream corridors. Attributes such as the
structure of native plant communities
can physically affect the amount of
runoff entering a stream system through
uptake, absorption, and interruption.
Vegetation in the corridor can filter out
much of the overland flow of nutrients,
sediment, and water.
Siltation in larger streams can be re-
duced through a network of stream cor-
ridors functioning to filter excessive
sediment. Stream corridors filter many
of the upland materials from moving
unimpeded across the landscape.
Ground water and surface water flows
are filtered by plant parts below and
above ground. Chemical elements are
intercepted by flora and fauna within
stream corridors. A wider corridor pro-
vides more effective filtering, and a con-
tiguous corridor functions as a filter
along its entire length.
Breaks in a stream corridor can some-
times have the effect of funneling dam-
aging processes into that area. For
example, a gap in contiguous vegetation
along a stream corridor can reduce the
filtering function by focusing increased
runoff into the area, leading to erosion,
2-84
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
no
vegetative
buffer
narrow
vegetative
buffer
wide
vegetative
buffer
Figure 2.40: The width of the vegetation buffer influences filter and barrier functions.
Dissolved substances, such as nitrogen, phosphorus, and other nutrients, entering a vegetated
stream corridor are restricted from entering the channel by friction, root absorption, clay, and
soil organic matter.
Adapted from Ecology of Greenways: Design and Function of Linear Conservation Areas.
Edited by Smith and Hellmund. © University of Minnesota Press 1993.
gullying, and the free flow of sediments
and nutrients into the stream.
Edges at the boundaries of stream corri-
dors begin the process of filtering.
Abrupt edges concentrate initial filter-
ing functions into a narrow area. A
gradual edge increases filtering and
spreads it across a wider ecological
gradient (Figure 2.41).
Movement parallel to the corridor is
affected by coves and lobes of an un-
even corridor's edge. These act as barri-
ers or filters for materials flowing into
the corridor. Individual plants may
selectively capture materials such as
wind-borne sediment, carbon, or pro-
pagules as they pass through a convo-
luted edge. Herbivores traveling along
a boundary edge, for example, may stop
to rest and selectively feed in a shel-
tered nook. The wind blows a few seeds
into the corridor, and those suited to
the conditions of the corridor may ger-
minate and establish a population. The
lobes have acted as a selective filter col-
lecting some seeds at the edge and al-
lowing other species to interact at the
boundary (Forman 1995).
Figure 2.41: Edges can be (a) abrupt or
(b) gradual. Abrupt edges, usually caused
by disturbances, tend to discourage movement
between ecosystems and promote movement
along the boundary. Gradual edges usually
occur in natural settings, are more diverse,
and encourage movement between ecosystems.
Functions and Dynamic Equilibrium
2-85
-------
In constantly
changing
ecosystems
like stream cor-
ridors, stability
is the ability of
a system to
persist within
a range of con-
ditions. This
phenomenon
is referred to
as dynamic
equilibrium.
Source and Sink Functions
*^Xj^ ^^\^
Sources provide organisms, energy or
materials to the surrounding landscape.
Areas that function as sinks absorb or-
ganisms, energy, or materials from the
surrounding landscape. Influent and ef-
fluent reaches, discussed in Section l.B
of Chapter 1, are classic examples of
sources and sinks. The influent or "los-
ing" reach is a source of water to the
aquifer, and the effluent or "gaining"
reach is a sink for ground water.
Stream corridors or features within them
can act as a source or a sink of environ-
mental materials. Some stream corridors
act as both, depending on the time of
year or location in the corridor. Stream-
banks most often act as a source, for
example, of sediment to the stream. At
times, however, they can function as
sinks while flooding deposits new sedi-
ments there. At the landscape scale, cor-
ridors are connectors to various other
patches of habitats in the landscape and
as such they are sources and conduits of
genetic material throughout the land-
scape.
Stream corridors can also act as a sink
for storage of surface water, ground
water, nutrients, energy, and sediment
allowing for materials to be temporarily
fixed in the corridor. Dissolved sub-
stances, such as nitrogen, phosphorus,
and other nutrients, entering a vege-
tated stream corridor are restricted from
entering the channel by friction, root
absorption, clay, and soil organic mat-
ter. Although these functions of source
and sink are conceptually understood,
they lack a suitable body of research
and practical application guidelines.
Forman (1995) offers three source and
sink functions resulting from floodplain
vegetation:
Decreased downstream flooding
through floodwater moderation
and/or uptake
Containment of sediments and
other materials during flood stage
Source of soil and water organic
matter
Biotic and genetic source/sink relation-
ships can be complex. Interior forest
birds are vulnerable to nest parasitism
by cowbirds when they try to nest in
too small a forest patch. For these
species, small forest patches can be
considered sinks that reduce their pop-
ulation numbers and genetic diversity
by causing failed reproduction. Large
forest patches with sufficient interior
habitat, in comparison, support success-
ful reproduction and serve as sources of
more individuals and new genetic com-
binations.
Dynamic Equilibrium
The first two chapters of this document
have emphasized that, although stream
corridors display consistent patterns in
their structure, processes, and functions,
these patterns change naturally and con-
stantly, even in the absence of human
disturbance. Despite frequent change,
streams and their corridors exhibit a
dynamic form of stability. In constantly
changing ecosystems like stream corri-
dors, stability is the ability of a system
to persist within a range of conditions.
This phenomenon is referred to as
dynamic equilibrium.
The maintenance of dynamic equilib-
rium requires that a series of self-cor-
recting mechanisms be active in the
stream corridor ecosystem. These mech-
2-86
Chapter 2: Stream Corridor Processes, Characteristics, and Functions
-------
anisms allow the ecosystem to control
external stresses or disturbances within
a certain range of responses thereby
maintaining a self-sustaining condition.
The threshold levels associated with
these ranges are difficult to identify and
quantify. If they are exceeded, the sys-
tem can become unstable. Corridors
may then undergo a series of adjust-
ments to achieve a new steady state
condition, but usually after a long pe-
riod of time has elapsed.
Many stream systems can accommodate
fairly significant disturbances and still
return to functional condition in a rea-
sonable time frame, once the source of
the disturbance is controlled or re-
moved. Passive restoration is based on
this tendency of ecosystems to heal
themselves when external stresses are
removed. Often the removal of stress
and the time to recover naturally are an
economical and effective restoration
strategy. When significant disturbance
and alteration has occurred, however, a
stream corridor may require several
decades to restore itself. Even then, the
recovered system may be a very differ-
ent type of stream that, although at
equilibrium again, is of severely dimin-
ished ecological value in comparison
with its previous potential. When
restoration practitioners' analysis indi-
cates lengthy recovery time or dubious
recovery potential for a stream, they
may decide to use active restoration
techniques to reestablish a more func-
tional channel form, corridor structure,
and biological community in a much
shorter time frame. The main benefit of
an active restoration approach is regain-
ing functionality more quickly, but the
biggest challenge is to plan, design, and
implement correctly to reestablish the
desired state of dynamic equilibrium.
This new equilibrium condition, how-
ever, may not be the same that existed
prior to the initial occurrence of the dis-
Stability, Disturbance, and Recovery
Stability, as a characteristic of ecosystems, combines
the concepts of resistance, resilience, and recovery.
Resistance is the ability to maintain original form and
functions. Resilience is the rate at which a system returns
to a stable condition after a disturbance. Recovery is the
degree to which a system returns to its original condition
after a disturbance. Natural systems have developed
ways of coping with disturbance, in order to produce
recovery and stability. Human activities often superim-
pose additional disturbances which may exceed the
recovery capability of a natural system. The fact that
change occurs, however, does not always mean a system
is unstable or in poor condition.
The term mosaic stability is used to denote the stability
of a larger system within which local changes still take
place. Mosaic stability, or the lack thereof, illustrates the
importance of the landscape perspective in making site-
specific decisions. For example, in a rapidly urbanizing
landscape, a riparian system denuded by a 100-year
flood may represent a harmful break in already dimin-
ished habitat that splits and isolates populations of a
rare amphibian species. In contrast, the same riparian
system undergoing flooding in a less-developed land-
scape may not be a geographic barrier to the amphibian,
but merely the mosaic of constantly shifting suitable and
unsuitable habitats in an unconfined, naturally function-
ing stream. The latter landscape with mosaic stability is
not likely to need restoration while the former landscape
without mosaic stability is likely to need it urgently.
Successful restoration of any stream corridor requires an
understanding of these key underlying concepts.
turbance. In addition, disturbances can
often stress the system beyond its nat-
ural ability to recover. In these instances
restoration is needed to remove the
cause of the disturbance or stress (pas-
sive) or to repair damages to the struc-
ture and functions of the stream
corridor ecosystem (active).
Functions and Dynamic Equilibrium
2-87
-------
-------
Disturbance
Affecting
Stream Corridors
J»
-------
3.A Natural Disturbances
How does natural disturbance contribute to shaping a local ecology?
Are natural disturbances bad?
How do you describe or define the frequency and magnitude of natural disturbance?
How does an ecosystem respond to natural disturbances?
What are some types of natural disturbances you should anticipate in a stream
corridor restoration?
3.B Human-Induced Disturbances
What are some examples of human-induced disturbances at several landscape scales?
What are the effects of some common human-induced disturbances such as dams,
channelization, and the introduction of exotic species?
What are some of the effects of land use activities such as agriculture, forestry, mining, graz-
ing, recreation, and urbanization?
-------
Disturbance
Affecting
Stream
Corridors
3.A Natural Disturbances
3.B Human-Induced Distrubances
Disturbances that bring changes to
stream corridors and associated
ecosystems are natural events or human-
induced activities that occur separately or
simultaneously (Figure 3.1). Either individ-
ually or in combination, disturbances
place stresses on the stream corridor that
have the potential to alter its structure
and impair its ability to perform key eco-
logical functions. The true impact of these
disturbances can
best be understood by how they affect
the ecosystem structure, processes, and
functions introduced in Chapters 1 and 2.
A disturbance occurring within or adjacent
to a corridor typically produces a causal
chain of effects, which may permanently
alter one or more characteristics of a
stable system. A view of this chain is
illustrated in Figure 3.2 (Wesche 1985).
This view can be applied in many stream
corridor restoration initiatives with the
ideal goal of moving back
as far as feasible on
the cause-effect chain
to plan and select
restoration alternatives
Figure 3.1: Disturbance in the
stream corridor. Both natural
and human-induced distur-
bances result in changes to
stream corridors.
-------
changes in
land or stream
corridor use
changes in
geomorphology
and hydrology
changes in
stream
hydraulics
changes in function
such as habitat,
sediment transport,
.and storage
changes in
population,
composition, and
distribution,
eutrophication,
and lower water
table elevations
Figure 3.2: Chain of events due to disturbance.
Disturbance to a stream corridor system typical-
ly results in a causal chain of alterations to
stream corridor structure and functions.
(Armour and Williamson 1988).
Otherwise, chosen alternatives may
merely treat symptoms rather than
the source of the problem.
Using this broad goal along with
the thoughtful use of a responsive
evaluation and design process will
greatly reduce the need for trial-
and-error experiences and enhance
the opportunities for successful
restoration. Passive restoration, as
the critical first option to pursue,
will result.
Disturbances can occur anywhere
within the stream corridor and as-
sociated ecosystems and can vary in
terms of frequency, duration, and
intensity. A single disturbance event
may trigger a variety of distur-
bances that differ in frequency, du-
ration, intensity, and location. Each
of these subsequent forms of direct
or indirect disturbance should be
addressed in restoration planning
and design for successful results.
This chapter focuses on under-
standing how various disturbances
affect the stream corridor and asso-
ciated ecosystems. We can better
determine what actions are needed
to restore stream corridor structure
and functions by understanding the
evolution of what disturbances are
stressing the system, and how the
system responds to those stresses.
Section 3.A: Natural Disturbances
This section introduces natural dis-
turbances as a multitude of poten-
tial events that cover a broad range
of temporal and spatial scales.
Often the agents of natural regen-
eration and restoration, natural dis-
turbances are presented briefly as
part of the dynamic system and
evolutionary process at work in
stream corridors.
Section 3.B: Human-Induced
Disturbances
Traditionally the use and manage-
ment of stream corridors have fo-
cused on the health and safety or
material wealth of society. Human-
induced forms of disturbances and
resulting effects on the ecological
structure and functions of stream
corridors are, therefore, common.
This section briefly describes some
of these major disturbance activities
and their potential effects.
3-2
Chapter 3: Disturbance Affecting Stream Corridors
-------
Changes on Broad Temporal
and Spatial Scales
Disturbance occurs within variations of
scale and time. Changes brought about
by land use, for example, may occur with-
in a single year at the stream or reach
scale (crop rotation), a decade within the
corridor or stream scale (urbanization),
and even over decades within the land-
scape or corridor scale (long-term forest
management). Wildlife populations, such
as monarch butterfly populations, may
fluctuate wildly from year to year in a
given locality while remaining nationally
stable over several decades. Geomorphic
or climatic changes may occur over hun-
dreds to thousands of years, while weath-
er changes daily.
Tectonics alter landscapes over periods of
hundreds to millions of years, typically
beyond the limits of human observance.
Tectonics involves mountain-building
forces like folding and faulting or earth-
quakes that modify the elevation of the
earth's surface and change the slope of
the land. In response to such changes, a
stream typically will modify its cross sec-
tion or its planform. Climatic changes, in
contrast, have been historically and even
geologically recorded. The quantity, tim-
ing, and distribution of precipitation often
causes major changes in the patterns of
vegetation, soils, and runoff in a land-
scape. Stream corridors subsequently
change as runoff and sediment loads vary.
3.A Natural Disturbances
Floods, hurricanes, tornadoes, fire,
lightning, volcanic eruptions, earth-
quakes, insects and disease, landslides,
temperature extremes, and drought are
among the many natural events that
disturb structure and functions in the
stream corridor (Figure 3.3). How
ecosystems respond to these distur-
bances varies according to their relative
stability, resistance, and resilience. In
many instances they recover with little
or no need for supplemental restora-
tion work.
Natural disturbances are sometimes
agents of regeneration and restoration.
Certain species of riparian plants, for
example, have adapted their life cycles
to include the occurrence of destruc-
tive, high-energy disturbances, such as
alternating floods and drought.
In general, riparian vegetation is re-
silient. A flood that destroys a mature
cottonwood gallery forest also com-
monly creates nursery conditions nec-
essary for the establishment of a new
forest (Brady et al. 1985), thereby in-
creasing the resilience and degree of re-
covery of the riparian system.
Figure 3.3: Drought
one of many types of
natural disturbance.
How a stream corri-
dor responds to dis-
turbances depends on
its relative stability,
resistance, and
resilience.
Natural Disturbances
3-3
-------
Ecosystem Resilience in Eastern
Upland Forests
Eastern upland forest systems, dominated by
stands of beech/maple, have adapted to many
types of natural disturbances by evolving attributes
such as high biomass and deep, established root
systems (Figure 3.4). Consequently, they are rela-
tively unperturbed by drought or other natural dis-
turbances that occur at regular intervals. Even
when unexpected severe stress such as fire or
insect damage occurs, the impact is usually only
on a local scale and therefore insignificant in the
persistence of the community as a whole.
Resilience of the Eastern Upland Forest can be dis-
rupted, however, by widespread effects such as
acid rain and indiscriminate logging and associated
road building. These and other disturbances have
the potential to severely alter lighting conditions,
soil moisture, soil nutrients, soil temperature,
and other factors critical for persistence of the
beech/maple forest. Recovery of an eastern
"climax" system after a widespread disturbance
might take more than 150 years.
Figure 3.4: Eastern upland forest system. The beech/maple-dominated system is resistent to many natural forms of
stress due to high biomass; deep, established root systems; and other adaptations.
3-4
Chapter 3: Disturbance Affecting Stream Corridors
-------
CASE5IUDY Before the Next Flood
Recently the process of recovery from major
flood events has taken on a new dimension.
Environmental easements, land acquisition, and
relocation of vulnerable structures have become
more prominent tools to assist recovery and
reduce long-term flood vulnerability. In addition
to meeting the needs of disaster victims, these
actions can also be effective in achieving stream
corridor restoration. Local interest in and support
for stream corridor restoration may be high after
a large flood event, when the flood waters recede
and the extent of property damage can be fully
assessed. At this point, public recognition of the
costly and repetitive nature of flooding can pro-
vide the impetus needed for communities and
individuals to seek better solutions. Advanced
planning on a systemwide basis facilitates identifi-
cation of areas most suited to levee setback, land
acquisition, and relocation.
The city of Arnold, Missouri, is located about 20
miles southwest of St. Louis at the confluence of
the Meramec and Mississippi Rivers. When the
Mississippi River overflows its banks, the city of
Arnold experiences backwater conditionsriver
water is forced back into the Meramec River,
causing flooding along the Meramec and smaller
tributaries to the Meramec. The floodplains of the
Mississippi, Meramec, and local tributaries have
been extensively developed. This development has
decreased the natural function of the floodplain.
In 1991 Arnold adopted a floodplain manage-
ment plan that included, but was not limited to,
a greenway to supplement the floodplain of the
Mississippi River, an acquisition and relocation
program to facilitate creation of the greenway,
regulations to guide future development and
ensure its consistency with the floodplain man-
agement objectives, and a watershed manage-
ment plan. The 1993 floods devastated Arnold
(Figure 3.5). More than $2 million was spent on
federal disaster assistance to individuals, and the
city's acquisition program spent $7.3 million in
property buyouts. Although not as severe as the
1993 floods, the 1995 floods were the fourth
largest in Arnold's history. Because of the reloca-
tion and other floodplain management efforts,
federal assistance to individuals totaled less than
$40,000. As the city of Arnold demonstrated,
having a local floodplain management plan in
place before a flood makes it easier to take
advantage of the mitigation opportunities after
a severe flood.
Across the Midwest, the 1993 floods resulted in
record losses with over 55,000 homes flooded.
Total damage estimates ranged between $12
billion and $16 billion. About half of the damage
was to residences, businesses, public facilities,
and transportation infrastructure. The Federal
Emergency Management Agency and the U.S.
Department of Housing and Urban Development
were able to make considerably more funding
available for acquisition, relocation, and raising
the elevation of properties than had been avail-
able in the past. The U.S. Fish and Wildlife Service
and state agencies were also able to acquire
property easements along the rivers. As a result,
losses from the 1995 floods in the same areas
were reduced and the avoided losses will contin-
ue into the future. In addition to reducing the
potential for future flood damages, the acquisi-
tion of property in floodplains and the subse-
quent conversion of that property into open
space provides an opportunity for the return of
the natural functions of stream corridors.
Figure 3.5: Flooding in Arnold, Missouri (1983).
Natural Disturbances
3-5
-------
3.B Human-Induced Disturbances
Human-induced
disturbances
brought about
by land use
activities un-
doubtedly have
the greatest
potential for
introducing en-
during changes
to the ecologi-
cal structure
and functions
of stream
corridors.
Human-induced disturbances brought
about by land use activities undoubt-
edly have the greatest potential for in-
troducing enduring changes to the
ecological structure and functions of
stream corridors (Figure 3.6). Chemi-
cally defined disturbance effects, for ex-
ample, can be introduced through
many activities including agriculture
(pesticides and nutrients), urban activi-
ties (municipal and industrial waste
contaminants), and mining (acid mine
drainage and heavy metals).
They have the potential to disturb nat-
ural chemical cycles in streams, and
thus to degrade water quality. Chemical
disturbances from agriculture are
usually widespread, nonpoint sources.
Municipal and industrial waste conta-
minants are typically point sources and
often chronic in duration. Secondary
effects, such as agricultural chemicals
attached to sediments and increased
soil salinity, frequently occur as a result
of physical activities (irrigation or
heavy application of herbicide). In
these cases, it is better to control the
physical activity at its source than to
treat the symptoms within a stream
corridor.
Biologically defined disturbance effects
occur within species (competition, can-
nibalism, etc.) and among species
(competition, predation, etc.). These
are natural interactions that are impor-
tant determinants of population size
and community organization in many
ecosystems. Biological disturbances due
to improper grazing management or
recreational activities are frequently
encountered. The introduction of
exotic flora and fauna species can in-
troduce widespread, intense, and con-
tinuous stress on native biological
communities.
Physical disturbance effects occur at
any scale from landscape and stream
corridor to stream and reach, where
they can cause impacts locally or at lo-
cations far removed from the site of
origin. Activities such as flood control,
forest management, road building and
maintenance, agricultural tillage, and
irrigation, as well as urban encroach-
ment, can have dramatic effects on the
geomorphology and hydrology of a wa-
tershed and the stream corridor mor-
phology within it. By altering the
structure of plant communities and
soils, these and other activities can af-
fect the infiltration and movement of
water, thereby altering the timing and
magnitude of runoff events. These dis-
turbances also occur at the reach scale
and cause changes that can be ad-
dressed in stream corridor restoration.
The modification of stream hydraulics,
for example, directly affects the system,
Figure 3.6: Agricultural activity. Land use activi-
ties can cause extensive physical, biological, or
chemical disturbances in a watershed and
stream corridor.
3-6
Chapter 3: Disturbance Affecting Stream Corridors
-------
causing an increase in the intensity of
disturbances caused by floods.
This section is divided into two subsec-
tions. Common disturbances are dis-
cussed first, followed by land use
activities.
Common Disturbances
Dams, channelization, and the intro-
duction of exotic species represent
forms of disturbance found in many
if not all of the land uses discussed
later in this chapter. Therefore, they
are presented as separate discussions
in advance of more specific land use
activities that potentially introduce
disturbance. Many societal benefits are
derived from these land use changes.
This document, however, focuses on
their potential for disturbance and sub-
sequent restoration of stream corridors.
Dams
Ranging from small temporary struc-
tures constructed of stream sediment to
huge multipurpose structures, dams
can have profound and varying impacts
on stream corridors (Figure 3.7). The
extent and impact largely depend on
the purposes of the dam and its size in
relation to stream flow.
Changes in discharges from dams can
cause downstream effects. Hydropower
dam discharges may vary widely on a
hourly and daily basis in response to
peaking power needs and affect the
downstream morphology. The rate of
change in the discharge can be a signif-
icant factor increasing streambank ero-
sion and subsequent loss of riparian
habitat. Dams release water that differs
from that received. Flowing streams can
slow and change into slack water pools,
sometimes becoming lacustrine envi-
ronments. A water supply dam can de-
crease instream flows, which alters the
stream corridor morphology, plant
Figure 3.7: An impoundment dam. Dams range
widely in size and purpose, and in their effects
on stream corridors.
communities, and habitat or can aug-
ment flows, which also results in alter-
ations to the stream corridor.
Dams affect resident and migratory
organisms in stream channels. The
disruption of flow blocks or slows the
passage and migration of aquatic or-
ganisms, which in turn affects food
chains associated with stream corridor
functions (Figure 3.8). Without high
flows, silt is not washed from the gravel
beds on which many aquatic species
rely for spawning. Upstream fish move-
ment may be blocked by relatively
small structures. Downstream move-
ment may be slowed or stopped by the
dam or its reservoir. As a stream current
dissipates in a reservoir, smolts of
anadromous fish may lose a sense of
downstream direction or might be sub-
ject to more predation, altered water
chemistry, and other effects.
Dams also affect species by altering
water quality. Relatively constant flows
can create constant temperatures,
Human-Induced Disturbances
3-7
-------
which affect those species dependent
on temperature variations for reproduc-
tion or maturation. In places where ir-
rigation water is stored, unnaturally
low flows can occur and warm more
easily and hold less oxygen, which can
cause stress or death in aquatic organ-
isms. Likewise, large storage pools keep
water cool, and released water can re-
sult in significantly cooler temperatures
downstream to which native fish might
not be adapted.
Dams also disrupt the flow of sediment
and organic materials (Ward and
Standford 1979). This is particularly
evident with the largest dams, whereas
dams which are typically low in eleva-
tion and have small pools modify nat-
ural flood and transport cycles only
slightly. As stream flow slackens, the
load of suspended sediment decreases
and sediment drops out of the stream
to the reservoir bottom. Organic mater-
ial suspended in the sediment, which
provides vital nutrients for downstream
food webs, also drops out and is lost to
the stream ecosystem.
When suspended sediment load is de-
creased, scouring of the downstream
Figure 3.8: Biological effects of dams. Dams
can prevent the migration of anadromous fish
and other aquatic organisms.
streambed and banks may occur until
the equilibrium bed load is reestab-
lished. Scouring lowers the streambed
and erodes streambanks and riparian
zones, vital habitat for many species.
Without new sources of sediment,
sandbars alongside and within streams
are eventually lost, along with the
habitats and species they support.
Additionally, as the stream channel
becomes incised, the water table under-
lying the riparian zone also lowers.
Thus, channel incision can lead to ad-
verse changes in the composition of
vegetative communities within the
stream corridor.
Conversely, when dams are constructed
and operated to reduce flood damages,
the lack of large flood events can result
in channel aggradation and the narrow-
ing and infilling of secondary channels
(Collier et al. 1996).
Channelization and Diversions
Like dams, channelization and diver-
sions cause changes to stream corri-
dors. Stream channelization and
diversions can disrupt riffle and pool
complexes needed at different times in
the life cycle of certain aquatic organ-
isms. The flood conveyance benefits of
channelization and diversions are often
offset by ecological losses resulting
from increased stream velocities and re-
duced habitat diversity. Instream modi-
fications such as uniform cross section
and armoring result in less habitat for
organisms living in or on stream sedi-
ments (Figure 3.10). Habitat is also
lost when large woody debris, which
frequently supports a high density of
aquatic macroinvertebrates, is removed
(Bisson et al. 1987, Sweeney 1992).
The impacts of diversions on the
stream corridor depend on the timing
and amount of water diverted, as well
as the location, design, and operation
3-8
Chapter 3: Disturbance Affecting Stream Corridors
-------
CASE5IUPY The Glen Canyon Dam Spiked Flow
ft? Experiment
The Colorado River watershed is a 242,000-
square-mile mosaic of mountains, deserts, and
canyons. The watershed begins at over 14,000
feet in the Rocky Mountains and ends at the Sea
of Cortez. Many native species require very specific
environments and ecosystem processes to survive.
Before settlement of the Colorado River water-
shed, the basin's rivers and streams were charac-
terized by a large stochastic variability in the annu-
al and seasonal flow levels. This was representative
of the highly variable levels of moisture and runoff.
This hydrologic variability was a key factor in the
evolution of the basin's ecosystems.
Settlement and subsequent development and man-
agement of the waters of the Colorado River sys-
tem detrimentally affected the ecological processes.
Today over 40 dams and diversion structures con-
trol the river system and result in extensive frag-
mentation of the watershed and riverine ecosys-
tem. Watershed development, in addition to the
dams, has also resulted in modifications to the
hydrology and the sediment input.
Historically, flood flows moved nutrients into the
ecosystem, carved the canyons, and redistributed
sand from the river bottom creating sandbars and
backwaters where fish could breed and grow. In
1963, the closure of Glen Canyon Dam, about 15
miles upstream of the Grand Canyon, permanently
altered these processes (Figure 3.9). In the spring
of 1996 the Bureau of Reclamation ran the first
controlled release of water from Glen Canyon Dam
to test and study the ability to use "spike flows"
for redistribution of sediment (sand) from the river
bottom to the river's margins in eddy zones. The
primary objective of the controlled release of large
flows was to restore portions of the ecological
equation by mimicking the annual floods which
used to occur in the Grand Canyon.
Flow releases of 45,000 cfs were maintained for
one week. The results were mixed. The flood
heightened and slightly widened existing sandbars.
It built scores of new camping beaches and provid-
ed additional protection for archeological sites
threatened with loss from erosion. The spike flow
also liberated large quantities of vital nutrients. It
created 20 percent more backwater areas for
spawning native fish. No endangered species were
significantly harmed, nor was the trout fishery
immediately below Glen Canyon Dam harmed. The
flow was not, however, strong enough to flush
some nonnative species (e.g., tamarisk) from the
system as had been hoped. One important finding
was that most of the ecological effects were real-
ized during the first 48 hours of the week-long
high-flow conditions.
The Bureau of Reclamation is continuing to moni-
tor the effects of the spike flow. The effects of the
restorative flood are not permanent. New beaches
and sandbars will continue to erode. An adaptive
management approach will help guide future deci-
sions about spike flows and management of flows
to better balance the competing needs for
hydropower, flood protection, and preservation of
the Grand Canyon ecosystem. It might be that
short spike flows are ecologically more acceptable.
Changing flow releases provides another tool that,
if properly used, can help restore ecological
processes that are essential for maintaining ecosys-
tem health and biodiversity.
Figure 3.9: Glen Canyon Dam. The Glen Canyon Dam
permanently altered downstream functions and ecology.
Human-Induced Disturbances
3-9
-------
Flood damage
reduction mea-
sures encom-
pass a wide
variety of
strategies,
some of which
might not be
compatible
with goals of
stream corridor
restoration.
of the diversion structure or its pumps
(Figure 3.11). The effects of diversions
on stream flows are similar to those ad-
dressed for dams. The effects of levees
depend on siting considerations, de-
sign, and maintenance practices.
Earthen diversion channels leak, and
the water lost for irrigation may create
wetlands. Leakage may support a vege-
tative corridor approaching that of a
simple riparian community, or it can
facilitate spread of exotic species, such
as tamarisk (Tamarisk chinensis). Diver-
sions can also trap fish, resulting in di-
minished spawning, lowered health of
species, and death of fish.
Flood damage reduction measures en-
compass a wide variety of strategies,
some of which might not be compati-
ble with goals of stream corridor
restoration. Floodwalls and levees can
increase the velocity of the stream and
elevate flood heights by constraining
high flows of the river to a narrow
band. When floodwalls are set farther
back from streams, they can define the
stream corridor and for some or all of
Figure 3.10: Stream channelization. Instream
modifications, such as uniform cross section
and armoring, result in ecological decline.
the natural functions of the floodplain,
including temporary flood storage.
Levees juxtaposed to streams tend to
replace riparian vegetation. The loss or
diminishment of the tree overstory and
other riparian vegetation results in the
changes in shading, temperature, and
nutrients discussed earlier.
Introduction of Exotic Species
Stream corridors naturally evolve in an
environment of fluctuating flows and
seasonal rhythms. Native species
adapted to such conditions might not
survive without them. For stream corri-
dors that have naturally evolved in an
environment of spring floods and low
winter and summer flows, the diminu-
tion of such patterns can result in the
creation of a new succession of plants
and animals and the decline of native
species. In the West, nonnative species
like tamarisk can invade altered stream
corridors and result in creation of a
habitat with lower stability. The native
fauna might not secure the same sur-
vival benefits from this altered condi-
tion because they did not evolve with
tamarisk and are not adapted to using it.
The introduction of exotic species,
whether intentional or not, can cause
disruptions such as predation, hy-
bridization, and the introduction of
diseases. Nonnative species compete
with native species for moisture, nutri-
ents, sunlight, and space and can ad-
versely influence establishment rates
for new plantings, foods, and habitat.
In some cases, exotic plant species can
even detract from the recreational value
of streams by creating a dense, impene-
trable thicket along the streambank.
Well-known examples of the effects of
exotic species introduction include the
planned introduction of kudzu and the
inadvertent introduction of the zebra
mussel. Both species have imposed
3-10
Chapter 3: Disturbance Affecting Stream Corridors
-------
widespread, intense, and continuous
stress on native biological communi-
ties. Tamarisk (also known as salt
cedar) is perhaps the most renowned
exotic in North America. It is an aggres-
sive, exotic colonizer in the West due to
its high rate of seed production and
ability to withstand long periods of
inundation.
Figure 3.11: Stream diversion. Diversions are
built to provide water for numerous purposes,
including agriculture, industry, and drinking
water supplies.
Exotic Species in the West
Exotic animals are a common problem in
many areas of the West. "Wild" burros
wander up and down many desert wash-
es and stream corridors. Their destructive
foraging is often evident in sensitive ripar-
ian areas. Additionally, species such as
bullfrogs, not native to most of the West,
have been introduced in many waters
('Figure 3.121 Without the normal checks
and balances found in their native habitat
in the eastern United States, bullfrogs
reproduce prodigiously and prey on
numerous native amphibians, reptiles,
fish, and small mammals.
*i\\ '
Figure 3.12: Bullfrog. Without the normal
checks and balances found in the eastern
United States, bullfrogs in the West have
reproduced prodigiously.
Source: C. Zabawa.
Human-Induced Disturbances
3-11
-------
CASESTJLI^Y Salt Cedar Control at Bosque del
Wf Apache National Wildlife Refuge,
r
New Mexico
The exotic salt cedar (Tamarix chinensis) has
become the predominant woody species
along many of the stream corridors in the
Southwest. The wide distribution of this species
can be attributed to its ability to tolerate a wide
range of environmental factors and its adaptabili-
ty to new stream conditions accelerated by
human activities (e.g., summer flooding or no
flooding, reduced or altered water tables, high
salinity from agricultural tail water, and high levels
of sediment downstream from grazed water-
sheds). Salt cedar is particularly abundant on reg-
ulated rivers. Its ability to rapidly dominate ripari-
an habitat results in exclusion of cotton wood, wil-
low, and many other native riparian species.
Salt cedar control is an integral part of riparian
restoration and enhancement at Bosque del
Apache National Wildlife Refuge on the Rio
Grande in central New Mexico. Diverse mosaics
of native cottonwood/black willow (Populus fre-
montii/Salix nigra) forests, screw bean mesquite
(Prosobis pubescens) brushlands, and saltgrass
(Distichlis sp.) meadows have been affected by
this invasive exotic. The degree of infestation
varies widely throughout the refuge, ranging
from isolated plants to extensive monocultures
totaling thousands of acres. For the past 10
years, the refuge has experimented with me-
chanical and herbicide programs for feasible
control of salt cedar.
The refuge has experimented with several tech-
niques in controlling large salt cedar monocul-
tures prior to native plant establishment.
Herbicide/broadcast burn and mechanical tech-
niques have been employed on three 150-acre
units on the refuge (Figure 3.13). Initially, the
strategy for control was aerial application of a
low-toxicity herbicide, at 2 quarts/acre in the late
summer, followed by a broadcast prescribed burn
a year later. This control method appeared effec-
tive; however, extensive resprouting following the
burn indicated the herbicide might not have had
time to kill the plant prior to the burning.
Mechanical control using heavy equipment was
another option. Root plowing and raking have
long been used as a technique for salt cedar con-
trol. A plow is pulled by a bulldozer, severing salt
cedar root crowns from the remaining root mass
about 12 to 18 inches below the ground surface,
followed by root raking, which pulls the root
crowns from the ground for later stacking.
(b)
Figure 3.13: Salt cedar site (a) before and (b) after
treatment. Combinations of burning, chemical treat-
ment, and mechanical control techniques can be used
to control salt cedar, giving native vegetation an
opportunity to colonize and establish.
3-12
Chapter 3: Disturbance Affecting Stream Corridors
-------
There are advantages and disadvantages with
each technique (Table 3.1). Cost-effectiveness is
the distinct advantage of an herbicide/burn con-
trol program. Costs can be low if resprouting is
minor and burning removes much of the aerial
vegetation. Because an herbicide/burn program is
potentially cost-effective, this technique is again
being experimented with at the refuge. Costs are
being further reduced by combining the original
herbicide with a less expensive herbicide. A delay
of 2 years prior to broadcast burning is expected
to dramatically reduce resprouting, allowing time
for the herbicide to effectively move throughout
the entire plant. Disadvantages of herbicide appli-
cation include restrictions regarding application
near water bodies and impacts on native vegeta-
tion remnants within salt cedar monocultures.
Advantages of mechanical control include proven
effectiveness and more thorough site preparation
for revegetation. Disadvantages include signifi-
cant site disturbance, equipment
breakdowns/delays, and lower effectiveness in
tighter clay soils. Both methods require skill in
equipment operation, whether applying herbicide
aerially or operating heavy equipment.
Other salt cedar infestations on the refuge are
relatively minor, consisting of small groups of
plants or scattered individual plants. Nonetheless,
these patches are aggressively controlled to pre-
vent spread. Heavy equipment requires working
space and is generally restricted to sites of 1 acre
and larger. For these smaller areas, front end
loaders have been filled with "stinger bars,"
which remove individual plant root crowns much
like a root plow. For areas of less than 1 acre,
Bosque del Apache
National Wildlife
Refuge,
New Mexico
spof herbicide applications are made using a 1
percent solution from a small sprayer. To date,
approximately 1,000 acres of salt cedar have
been controlled, with over 500 acres effectively
restored to native riparian vegetative communi-
ties. A combination of techniques in the control
of salt cedar has proven effective and will contin-
ue to be used in the future.
Table 3.1: Salt cedar control techniques at Bosque del Apache.
Unit I Herbicide I Broadcast I Root I Root I Pile I %
I Burn I Plow I Rake I Burn I Control
28
29
30
88%
x 90%
x 99%
Human-Induced Disturbances
3-13
-------
Land Use Activities
Agriculture
According to the 1992 Natural Re-
sources Inventory (USDA-NRCS 1992),
cultivated and noncultivated cropland
make up approximately 382 million
acres of the roughly 1.9 billion acres
existing in the contiguous United
States, Hawaii, Puerto Rico, and the
U.S. Virgin Islands (excludes Alaska).
The conversion of undisturbed land to
agricultural production has often dis-
rupted the previously existing state of
dynamic equilibrium. Introduced at the
landscape, watershed, stream corridor,
stream, and reach scales, agricultural
activities have generally resulted in en-
croachment on stream corridors with
significant changes to the structure and
mix of functions usually found in sta-
ble systems (Figure 3.14).
Figure 3.14: Agriculture fragments natural
ecosystems. Cultivated and noncultivated crop-
land make up approximately 382 million acres
of the roughly 1.9 billion acres existing in the
contiguous United States, Hawaii, Puerto Rico,
and the U.S. Virgin Islands (excludes Alaska).
Vegetative Clearing
One of the most obvious disturbances
from agriculture involves the removal
of native, riparian, and upland vegeta-
tion. Producers often crop as much
productive land as possible to enhance
economic returns; therefore, vegetation
is sacrificed to increase arable acres.
As the composition and distribution of
vegetation are altered, the interactions
between structure and function become
fragmented. Vegetative removal from
streambanks, floodplains, and uplands
often conflicts with the hydrologic and
geomorphic functions of stream corri-
dors. These disturbances can result in
sheet and rill as well as gully erosion,
reduced infiltration, increased upland
surface runoff and transport of contam-
inants, increased streambank erosion,
unstable stream channels, and im-
paired habitat.
Instream Modifications
Flood-control structures and channel
modifications implemented to protect
agricultural systems further disrupt the
geomorphic and hydrologic characteris-
tics of stream corridors and associated
uplands. For agricultural purposes,
streams are often straightened or
moved to "square-up" fields for more
efficient production and reconstructed
to a new profile and geometric cross
section to accommodate increased
runoff. Stream corridors are also often
modified to enhance conditions for
single purposes such as fish habitat, or
to manage conditions such as localized
streambank erosion. Some of the po-
tential effects caused by these changes
are impaired upland or floodplain sur-
face and subsurface flow; increased
water temperature, turbidity, and pH;
incised channels; lower ground water
elevations; streambank failure; and loss
of habitat for aquatic and terrestrial
species.
3-14
Chapter 3: Disturbance Affecting Stream Corridors
-------
Soil Exposure and Compaction
Tillage and soil compaction interfere
with soil's capacity to partition and reg-
ulate the flow of water in the land-
scape, increase surface runoff, and
decrease the water-holding capacity of
soils. Increases in the rate and volume
of throughflow in the upper soil layers
are frequent. Tillage also often aids in
the development of a hard pan, a layer
of increased soil density and decreased
permeability that restricts the move-
ment of water into the subsurface.
The resulting changes in surface and
ground water flow often initiate incised
channels and effects similar to those
discussed previously for instream
modifications.
Irrigation and Drainage
Diverting surface water for irrigation
and depleting aquifers have brought
about major changes in stream corri-
dors. Aquifers have been a desired
source of water for agriculture because
ground water is usually high-quality
and historically abundant and is a
more reliable source than rivers, lakes,
and reservoirs (Figure 3.15). Under-
ground water supplies have diminished
at an alarming rate in the United
States, with ground water levels re-
ported to be dropping an estimated
foot or more a year under 45 percent of
the ground water-irrigated cropland
(Dickason 1988).
Agricultural drainage, which allows the
conversion of wetland soils to agricul-
tural production, lowers the water
table. Tile drainage systems concentrate
ground water discharge to a point
source, in contrast to a diffuse source
of seeps and springs in more natural
discharges. Subsurface tile drainage sys-
tems, constructed waterways, and
drainage ditches constitute a landscape
scale network of disturbances. These
practices have eliminated or frag-
Figure 3.15: Central pivot irrigation systems use
ground water sources. Reliance on aquifers for
irrigation has brought about major changes in
ground water supply, as well as the landscape.
mented habitat and natural filtration
systems needed to slow and purify
runoff. The results are often a com-
pressed and exaggerated hydrograph.
Sediment and Contaminants
Disturbance of soil associated with
agriculture generates runoff polluted
with sediment, a major nonpoint
source pollutant in the nation. Pesti-
cides and nutrients (mainly nitrogen,
phosphorous, and potassium) applied
during the growing season can leach
into ground water or flow in surface
water to stream corridors, either dis-
solved or adsorbed to soil particles. Ap-
plied aerially, these same chemicals can
drift into the stream corridor. Improper
storage and application of animal
waste from concentrated animal pro-
duction facilities are potential sources
of chemical and bacterial contaminants
to stream corridors.
Human-Induced Disturbances
3-15
-------
Soil salinity is a naturally occurring
phenomenon found most often in
floodplains and other low-lying areas
of wet soils, lakes, or shallow water ta-
bles. Dissolved salts in surface and
ground water entering these areas be-
come concentrated in the shallow
ground water and the soils as evapo-
transpiration removes water. Agricul-
tural activities in such landscapes can
increase the rate of soil salinization by
changing vegetation patterns or by ap-
plying irrigation water without ade-
quate drainage. In the arid and
semiarid areas of the West, irrigation
can import salts into a drainage basin.
Since crops do not use up the salts,
they accumulate in the soil. Salinity
levels greater than 4 millimhos/cm can
alter soil structure, promote waterlog-
ging, cause salt toxicity in plants, and
decrease the ability of plants to take up
water.
Drainage and Streambank Erosion
Many wetlands have been drained to increase the acres
of arable land. The drainage area of the Blue Earth River
in the glaciated areas of west-central Minnesota, for
example, has almost doubled due to extensive tile
drainage of depressional areas that formerly stored sur-
face runoff. Studies to identify sources of sediment in
this watershed have been made, and as a result, farmers
have complied with reduced tillage and increased crop
residue recommendations to help decrease the suspend-
ed sediment load in the river. Testing, however, indicates
the sediment problem has not been solved. Some indi-
viduals have suggested that streambank erosion, not
erosion on agricultural lands, might be the source of the
sediment. Streambank erosion is more likely to be the
result of drainage and subsequent changes to runoff
patterns in the watershed.
Forestry
Three general activities associated with
forestry operations can affect stream
corridorstree removal, activities nec-
essary to transport the harvested tim-
ber, and preparation of the harvest site
for regeneration.
Removal of Trees
Forest thinning includes the removal of
either mature trees or immature trees
to provide more growth capability for
the remaining trees. Final harvest re-
moves mature trees, either singularly or
in groups. Both activities reduce vegeta-
tive cover.
Tree removal decreases the quantity of
nutrients in the watershed since ap-
proximately one-half of the nutrients
in trees are in the trunks. Instream nu-
trient levels can increase if large limbs
fall into streams during harvesting and
decompose. Conversely, when tree
cover is removed, there is a short-term
increase in nutrient release followed by
long-term reduction in nutrient levels.
Removal of trees can affect the quality,
quantity, and timing of stream flows
for the same reasons that vegetative
clearing for agriculture does. If trees are
removed from a large portion of a wa-
tershed, flow quantity can increase ac-
cordingly. The overall effect depends
on the quantity of trees removed and
their proximity to the stream corridor
(Figure 3.16). Increases in flood peaks
can occur if vegetation in the area clos-
est to the stream is removed. Long-term
loss of riparian vegetation can result in
bank erosion and channel widening,
increasing the width/depth ratio (Hart-
man et al. 1987, Oliver and Hinckley
1987, Shields et al. 1994). Water tem-
perature can increase during summer
and decrease in winter by removal of
shade trees in riparian areas. Allowing
large limbs to fall into a stream and di-
3-16
Chapter 3: Disturbance Affecting Stream Corridors
-------
vert stream flow may alter flow patterns
and cause bank or bed erosion.
Removal of trees can reduce availability
of cavities for wildlife use and other-
wise alter biological systems, particu-
larly if a large percentage of the tree
cover is removed. Loss of habitat for
fish, invertebrates, aquatic mammals,
amphibians, birds, and reptiles can
occur.
Transportation of Products
Forest roads are constructed to move
loaded logs from the landing to higher-
quality roads and then to a manufac-
turing facility. Mechanical means to
move logs to a loading area (landing)
produce "skid trails." Stream crossings
are necessary along some skid trails
and most forest road systems and are
especially sensitive areas.
Removal of topsoil, soil compaction,
and disturbance by equipment and log
skidding can result in long-term loss of
productivity, decreased porosity, de-
creased soil infiltration, and increased
runoff and erosion. Spills of petroleum
products can contaminate soils. Trails,
roads, and landings can intercept
ground water flow and cause it to be-
come surface runoff.
Soil disturbance by logging equipment
can have direct physical impact on
habitat for a wide variety of amphib-
ians, mammals, fish, birds, and rep-
tiles, as well as physically harm
wildlife. Loss of cover, food, and other
needs can be critical. Sediment can clog
fish habitat, widen streams, and accel-
erate streambank erosion.
Site Preparation
Preparing the harvested area for the
next generation of desired trees typi-
cally includes some use of prescribed
fire or other methods to prepare a seed
bed and reduce competition from un-
wanted species.
Figure 3.16: Riparian forest. Streamside forest
cover serves many important functions such as
stabilizing streambanks and moderating diur-
nal stream temperatures.
Mechanical methods that completely
remove competing species can cause
severe compaction, particularly in wet
soils. This compaction reduces infiltra-
tion and increases runoff and erosion.
Moving logging debris into piles or
windrows can remove important nutri-
ents from the soil. Depending on the
methods used, significant soil can be
removed from the site and stacked with
piled debris, further reducing site pro-
ductivity.
Intense prescribed fire can volatilize
important nutrients, while less intense
fire can mobilize nutrients for rapid
plant uptake and growth. Use of fire
can also release nutrients to the stream
in unacceptable quantities.
Mechanical methods that cause signifi-
cant compaction or decrease infiltra-
tion can increase runoff and therefore
the amount of water entering the
stream system. Severe mechanical dis-
turbance can result in significant ero-
Human-lnduced Disturbances
3-17
-------
sion and sedimentation. Conversely,
less disruptive mechanical means can
increase organic matter in the soil sur-
face and increase infiltration. Each
method has advantages and disadvan-
tages.
Direct harm can occur to wildlife by
mechanical means or fire. Loss of habi-
tat can occur if site preparation physi-
cally removes most competing
vegetation. Loss of diversity can result
from efforts to strongly limit competi-
tion with desired timber species. Care-
less use of mechanical equipment can
directly damage streambanks and cause
erosion.
Domestic Livestock Crazing
Grazing of domestic livestock, primar-
ily cattle and sheep, is commonplace
across the nation. Stream corridors are
particularly attractive to livestock for
many reasons. They are generally
highly productive, providing ample for-
age. Water is close at hand, shade is
available to cool the area, and slopes
are gentle, generally less than 35 per-
cent in most areas. Unless carefully
managed, livestock can overuse these
areas and cause significant disturbance
(Figure 3.17). For purposes of the fol-
Figure 3.17: Livestock in stream. Use of stream
corridors by domestic livestock can result in
extensive physical disturbance and bacteriolog-
ical contamination.
lowing discussion, cattle grazing pro-
vides the focus, although sheep, goats,
and other less common species also
can have particular effects that might
be different from those discussed. It is
important to note that the effects dis-
cussed result from poorly managed
grazing systems.
The primary impacts that result from
grazing of domestic livestock are the
loss of vegetative cover due to its con-
sumption or trampling and streambank
erosion from the presence of livestock
(Table 3.2).
Loss of Vegetative Cover
Reduced vegetative cover can increase
soil compaction and decrease the depth
of and productivity of topsoil. Reduced
cover of mid-story and overstory plants
decreases shade and increases water
temperatures, although this effect di-
minishes as stream width increases.
Sediment from upland or streambank
erosion can reduce water quality
through increases in turbidity and at-
tached chemicals. Where animal con-
centrations are large, fecal material can
increase nutrient loads above standards
and introduce bacteria and pathogens,
although this is uncommon. Dissolved
oxygen reductions can result from high
temperature and nutrient-rich waters.
Extensive loss of ground cover in the
watershed and stream corridor can de-
crease infiltration and increase runoff,
leading to higher flood peaks and addi-
tional runoff volume. Where reduced
cover increases overland flow and pre-
vents infiltration, additional water may
flow more rapidly into stream channels
so that flow peaks come earlier rather
than later in the runoff cycle, produc-
ing a more "flashy" stream system. Re-
ductions in baseflow and increases in
stormflow can result in a formerly
perennial stream becoming intermit-
tent or ephemeral.
3-18
Chapter 3: Disturbance Affecting Stream Corridors
-------
Table 3.2: Livestock impacts on stream
corridors.
Decreased plant vigor
Decreased biomass
Alteration of species composition and diversity
Reduction or elimination of woody species
Elevated surface runoff
Erosion and sediment delivery to streams
Streambank erosion and failure
Channel instability
Increased width to depth ratios
Degradation of aquatic species
Water quality degradation
References: Ames (1977); Knopf and Cannon (1982); Hansen et al.
(1995); Kauff man and Kreuger (1984); Brooks et al. (1991); Plans
(1979); MacDonald etal. (1991).
Increased sedimentation of channels
can reduce channel capacity, increasing
width/depth ratios, forcing water into
streambanks, and inducing bank ero-
sion. This leads to channel instability,
causing other adjustments in the sys-
tem. Similarly, excessive water reaching
the system without additional sediment
may cause channel degradation as in-
creased stream energy erodes channel
bottoms, incising the channel.
Physical Impacts from Livestock
Presence
Trampling, trailing, and similar activi-
ties of livestock physically impact
stream corridors. Impacts on soils are
particularly dependent on soil moisture
content, with compaction presenting a
major concern. Effects vary markedly
by soil type and moisture content. Very
dry soils are seldom affected, while
very wet soils may also be resistant to
compaction. Moist soils are typically
more subject to compaction damage.
Very wet soils may be easily displaced,
however. Adjusting grazing use to peri-
ods where soil moisture will minimize
impacts will prevent many problems.
Compaction of soils by grazing animals
can cause increased soil bulk density,
reduced infiltration, and increased
runoff. Loss of capillarity reduces the
ability of water to move vertically and
laterally in the soil profile. Reduced
soil moisture content can reduce site
capacity for riparian-dependent plant
species and favor drier upland species.
Trailing can break down streambanks,
causing bank failure and increasing
sedimentation. Excessive trailing can
result in gully formation and eventual
channel extension and migration.
Unmanaged grazing can significantly
change stream geomorphology. Bank
instability and increased sedimentation
can cause channel widening and in-
creases in the width/depth ratio. In-
creased meandering may result, causing
further instability. Erosion of fine ma-
terials into the system can change
channel bottom composition and alter
sediment transport relationships.
Excessive livestock use can cause break-
age or other physical damage to
streamside vegetation. Loss of bank-
holding species and undercut banks
can reduce habitat for fish and other
aquatic species. Excessive sedimenta-
tion can result in filling of stream grav-
els with fine sediments, reducing the
survival of some fish eggs and newly
hatched fish due to lack of oxygen.
Excessive stream temperatures can
be detrimental to many critical fish
species, as well as amphibians. Loss
of preferred cover reduces habitat for
riparian-dependent species, particularly
birds.
Mining
Exploration, extraction, processing, and
transportation of coal, minerals, sand
and gravel, and other materials has had
and continues to have a profound ef-
fect on stream corridors across the na-
tion (Figure 3.18). Both surface
mining and subsurface mining damage
Human-Induced Disturbances
3-19
-------
stream corridors. Surface mining meth-
ods include strip mining, open-pit op-
erations, dredging, placer mining, and
hydraulic mining. Although several of
these methods are no longer com-
monly practiced today, many streams
throughout the United States remain in
a degraded condition as a result of
mining activities that, in some cases,
occurred more than a century ago.
Such mining activity frequently re-
sulted in total destruction of the stream
corridor. In some cases today, mining
operations still disturb most or all of
entire watersheds.
Figure 3.18: Results of surface mining. Many
streams remain in a degraded condition as a
result of mining activities.
Vegetative Clearing
Mining can often remove large areas of
vegetation at the mine site, transporta-
tion facilities, processing plant, tailings
piles, and related activities. Reduced
shade can increase water temperatures
enough to harm aquatic species.
Loss of cover vegetation, poor-quality
water, changes in food availability, dis-
ruption of migration patterns, and sim-
ilar difficulties can have serious effects
on terrestrial wildlife. Species composi-
tion may change significantly with a
shift to more tolerant species. Numbers
will likely drop as well. Mining holds
few positive benefits for most wildlife
species.
Soil Disturbance
Transportation, staging, loading, pro-
cessing, and similar activities cause ex-
tensive changes to soils including loss
of topsoils and soil compaction. Direct
displacement for construction of facili-
ties reduces the number of productive
soil acres in the watershed. Covering of
soil by materials such as tailings piles
further reduces the acreage of produc-
tive soils. These activities decrease infil-
tration, increase runoff, accelerate
erosion, and increase sedimentation.
Altered Hydrology
Changes to hydrologic conditions due
to mining activity are extensive. Surface
mining is, perhaps, the only land use
with a greater capacity to change the
hydrologic regime of a stream than ur-
banization. Increased runoff and de-
creased surface roughness will cause
peaks earlier in the hydrograph with
steeper rising and falling limbs. Once-
perennial streams may become inter-
mittent or ephemeral as baseflow
decreases.
Changes in the quantity of water leav-
ing a watershed are directly propor-
tional to the amount of impervious
3-20
Chapter 3: Disturbance Affecting Stream Corridors
-------
surface or reduced infiltration in a wa-
tershed. Loss of topsoils, soil com-
paction, loss of vegetation, and related
actions will decrease infiltration, in-
crease runoff, increase stormflow, and
decrease baseflows. Total water leaving
the watershed may increase due to re-
duced in-soil storage.
Stream geomorphology can change
dramatically, depending on the mining
method used. Floating dredges and hy-
draulic mining with high-pressure
hoses earlier in the century completely
altered streamcourses. In many places
virtually no trace of the original stream
character exists today. Flow may run
completely out of view into piles of
mine tailings. Once-meandering
streams may now be straight, gullied
channels. Less extreme mining meth-
ods can also significantly alter stream
form and function through steepening
or lowering the gradient, adding high
sediment loads, adding excessive water
to the system, or removing water from
the system.
Contaminants
Water and soils are contaminated by
acid mine drainage (AMD) and the ma-
terials used in mining. AMD, formed
from the oxidation of sulfide minerals
like pyrite, is widespread. Many hard
rock mines are located in iron sulfide
deposits. Upon exposure to water and
air, such deposits undergo sulfide oxi-
dation with attendant release of iron,
toxic metals (lead, copper, zinc), and
excessive acidity. Mercury was often
used to separate gold from the ore;
therefore, mercury was also lost into
streams. Present-day miners using suc-
tion dredges often find considerable
quantities of mercury still resident in
streambeds. Current heap-leaching
methods use cyanide to extract gold
from low-quality ores. This poses a spe-
cial risk if operations are not carefully
managed.
Toxic runoff or precipitates can kill
streamside vegetation or can cause a
shift to species more tolerant of mining
conditions. This affects habitat required
by many species for cover, food, and
reproduction.
Aquatic habitat suffers from several
factors. Acid mine drainage can coat
stream bottoms with iron precipitates,
thereby affecting the habitat for
bottom-dwelling and feeding organ-
isms. AMD also adds sulfuric acid to
the water, killing aquatic life. The low
pH alone can be toxic, and most met-
als exhibit higher solubility and more
bioavailability under acidic conditions.
Precipitates coating the stream bottom
can eliminate places for egg survival.
Fish that do hatch may face hostile
stream conditions due to poor water
quality, loss of cover, and limited food
base.
Recreation
The amount of impact caused by recre-
ation depends on soil type, vegetation
cover, topography, and intensity of use.
Various forms of foot and vehicular
traffic associated with recreational ac-
tivities can damage riparian vegetation
and soil structure. All-terrain vehicles,
for example, can cause increased ero-
sion and habitat reduction. At loca-
tions heavily used by hikers and
tourists, reduced infiltration due to soil
compaction and subsequent surface
runoff can result in increased sediment
loading to the stream (Cole and Mar-
ion 1988). Widening of the stream
channel can occur where hiking trails
cross the stream or where intensive use
destroys bank vegetation (Figure 3.19).
In areas where the stream can support
recreational boating, the system is vul-
nerable to additional impacts (Figure
Floating
dredges and
hydraulic min-
ing with high-
pressure hoses
earlier in the
century com-
pletely altered
streamcourses.
Human-Induced Disturbances
3-21
-------
YOU can make a difference!
Please help us restore
South Boulder Creek!
REMAIN ON THE
DESIGNATED TRAIL
Using small paths and creating
new trails causes unnecessary
impacts to the sensitive plants
and animals of the area.
Figure 3.19: Trail sign. Recreational hiking can
cause soil compaction and increased surface
runoff.
3.20). Propeller wash and water dis-
placement can disrupt and resuspend
bottom sediments, increase bank ero-
sion, and disorient or injure sensitive
aquatic species. In addition, waste dis-
charges or accidental spills from boats
or loading facilities can contribute pol-
lutants to the system (NRG 1992).
Both concentrated and dispersed recre-
ational use of stream corridors can
cause disturbance and ecological
change. Camping, hunting, fishing,
boating, and other forms of recreation
can cause serious disturbances to bird
colonies. Ecological damage primarily
results from the need for access for the
recreational user. A pool in the stream
might be the attraction for a swimmer
or fisherman, whereas a low stream-
bank might provide an access point for
boaters. In either case, a trail often de-
velops along the shortest or easiest
route to the point of access on the
stream. Additional impact may be a
function of the mode of access to the
stream: motorcycles and horses cause
far more damage to vegetation and
trails than do pedestrians.
Urbanization
Urbanization in watersheds poses spe-
cial challenges to the stream restoration
practitioner. Recent research has shown
that streams in urban watersheds have
a character fundamentally different
from that of streams in forested, rural,
or even agricultural watersheds. The
amount of impervious cover in the wa-
tershed can be used as an indicator to
predict how severe these differences
can be. In many regions of the country,
as little as 10 percent watershed imper-
vious cover has been linked to stream
degradation, with the degradation be-
coming more severe as impervious
cover increases (Schueler 1995).
Impervious cover directly influences
urban streams by dramatically increas-
ing surface runoff during storm events
(Figure 3.21). Depending on the de-
gree of watershed impervious cover, the
Figure 3.20: Recreational boating. Propeller
wash and accidental spills can degrade stream
conditions.
3-22
Chapter 3: Disturbance Affecting Stream Corridors
-------
annual volume of storm water runoff
can increase by 2 to 16 times its prede-
velopment rate, with proportional re-
ductions in ground water recharge
(Schueler 1995).
The unique character of urban streams
often requires unique restoration
strategies for the stream corridor. For
example, the practitioner must seri-
ously consider the degree of upland de-
velopment that has occurred or is
projected to occur. In most projects, it
is advisable or even necessary to inves-
tigate whether upstream detention or
retention can be provided within the
watershed to at least partially restore
the predevelopment hydrologic regime.
Some of the key changes in urban
streams that merit special attention
from the stream restoration practi-
tioner are discussed in the following
subsections.
Altered Hydrology
The peak discharge associated with the
bankfull flow (i.e., the 1.5- to 2-year re-
turn storm) increases sharply in magni-
tude in urban streams. In addition,
channels experience more bankfull
flood events each year and are exposed
to critical erosive velocities for longer
25% shallow
infiltration
Natural Ground Cover
21% deep
infiltration
10%-20% Impervious Surface
35% evapotranspiration
mm
30%
runoff
20% shallow
infiltration
4-
15% deep
infiltration
35%-50% Impervious Surface
30% evapotranspiration
D E3 C3 EJ EJ
anna
a a o a
a a o a
a a aa
n o o S3
10% shallow
infiltration
,
5% deep
infiltration
75%-100% Impervious Surface
Figure 3.21: Relationship between impervious cover and surface runoff. Impervious
cover in a watershed results in increased surface runoff. As little as 10 percent impervi-
ous cover in a watershed can result in stream degradation.
Human-Induced Disturbances
3-23
-------
intervals (Hollis 1975, Macrae 1996,
Booth and Jackson 1997).
Since impervious cover prevents rain-
fall from infiltrating into the soil, less
flow is available to recharge ground
water. Consequently, during extended
periods without rainfall, baseflow lev-
els are often reduced in urban streams
(Simmons and Reynolds 1982).
Altered Channels
The hydrologic regime that had defined
the geometry of the predevelopment
stream channel irreversibly changes to-
ward higher flow rates on a more fre-
quent basis. The higher flow events of
urban streams are capable of perform-
ing more "effective work" in moving
sediment than they had done before
(Wolman 1964).
The customary response of urban
streams is to increase their cross-
sectional area to accommodate the
higher flows. This is done by streambed
downcutting or streambank widening,
or a combination of both. Urban
stream channels often enlarge their
cross-sectional areas by a factor of 2 to
5, depending on the degree of impervi-
ous cover in the upland watershed and
the age of development (Arnold et al.
1982, Gregory et al. 1992, and Macrae
1996).
Stream channels react to urbanization
not only by adjusting their widths and
depths, but also by changing their gra-
dients and meanders (Riley 1998).
Urban stream channels are also exten-
sively modified in an effort to protect
adjacent property from streambank
erosion or flooding (Figure 3.22).
Headwater streams are frequently en-
closed within storm drains, while oth-
ers are channelized, lined, or armored
by heavy stone. Another modification
unique to urban streams is the installa-
tion of sanitary sewers underneath or
parallel to the stream channel.
The wetted perimeter of a stream is the
proportion of the total cross-sectional
area of the channel that is covered by
flowing water during dry-weather peri-
ods. It is an important indicator of
habitat degradation in urban streams.
Given that urban streams develop a
larger channel cross section at the same
time that their baseflow rates decline,
it necessarily follows that the wetted
perimeter will become smaller. Thus,
for many urban streams, this results in
a very shallow, low-flow channel that
wanders across a very wide streambed,
often changing its lateral position in
response to storms.
Sedimentation and Contaminants
The prodigious rate of channel erosion
in urban streams, coupled with sedi-
ment erosion from active construction
sites, increases sediment discharge to
urban streams. Researchers have docu-
mented that channel erosion consti-
tutes as much as 75 percent the total
sediment budget of urban streams
(Crawford and Lenat 1989, Trimble
1997). Urban streams also tend to have
a higher sediment discharge than
Figure 3.22: Urban stream channel modifica-
tions. Channel armoring often prevents
streams from accommodating hydrologic
changes that result from urbanization.
3-24
Chapter 3: Disturbance Affecting Stream Corridors
-------
nonurban streams, at least during the
initial period of active channel
enlargement.
The water quality of urban streams dur-
ing storm events is consistently poor.
Urban storm water runoff contains
moderate to high concentrations of
sediment, carbon, nutrients, trace met-
als, hydrocarbons, chlorides, and bacte-
ria (Schueler 1987) (Figure 3.23).
Although considerable debate exists as
to whether storm water pollutant con-
centrations are actually toxic to aquatic
organisms, researchers agree that pollu-
tants deposited in streambeds exert un-
desirable impacts on stream
communities.
Habitat and Aquatic Life
Urban streams are routinely scored as
having poor instream habitat quality,
regardless of the specific metric or
method employed. Habitat degradation
is often exemplified by loss of pool
and riffle structure, embedding of
streambed sediments, shallow depths
of flow, eroding and unstable banks,
and frequent streambed turnover.
Large woody debris (LWD) is an im-
portant structural component of many
low-order streams systems, creating
complex habitat structure and generally
making the stream more retentive. In
urban streams, the quantity of LWD
found in stream channels is reduced
due to the loss of riparian forest cover,
storm washout, and channel mainte-
nance practices (Booth et al. 1996, May
etal. 1997).
Many forms of urban development are
linear in nature (e.g., roads, sewers, and
pipelines) and cross stream channels.
The number of stream crossings in-
creases directly in proportion to imper-
vious cover (May et al. 1997), and
many crossings can become partial or
total barriers to upstream fish migra-
tion, particularly if the streambed
Figure 3.23: Water quality in urban streams.
Surface runoff carries numerous pollutants to
urban streams, resulting in consistently poor
water quality.
Source: C. Zabawa.
erodes below the fixed elevation of a
culvert or a pipeline.
The important role that riparian forests
play in stream ecology is often dimin-
ished in urban watersheds since tree
cover is often partially or totally re-
moved along the stream as a conse-
quence of development (May et al.
1997) (Figure 3.24). Even when stream
buffers are reserved, encroachment
often reduces their effective width and
native species are supplanted by exotic
trees, vines, and ground covers.
The impervious surfaces, ponds, and
poor riparian cover in urban water-
sheds can increase mean summer
stream temperatures by 2 to 10 degrees
Fahrenheit (Galli 1991). Since tempera-
ture plays a central role in the rate and
timing of biotic and abiotic reactions
in stream, such increases have an ad-
verse impact on streams. In some re-
gions, summer stream warming can
irreversibly shift a cold-water stream to
Human-Induced Disturbances
3-25
-------
Figure 3.24: Stream corridor encroachment.
Stream ecology is disturbed when riparian
forests are removed for development.
a cool-water or even warm-water
stream, with deleterious effects on
salmonoids and other temperature-
sensitive organisms.
Urban streams are typified by fair to
poor fish and macroinvertebrate diver-
sity, even at relatively low levels of wa-
tershed impervious cover or population
density (Schueler 1995, Shaver et al.
1995, Couch 1997, May et al. 1997).
The ability to restore predevelopment
fish assemblages or aquatic diversity is
constrained by a host of factorsirre-
versible changes in carbon supply, tem-
perature, hydrology, lack of instream
habitat structure, and barriers that limit
natural recolonization.
Summary of Potential Effects of
Land Use Activities
Table 3.3 presents a summary of the
disturbance activities associated with
major land uses and their potential for
changing stream corridor functions.
Many of the potential effects of distur-
bance are cumulative or synergistic.
Restoration might not remove all dis-
turbance factors; however, addressing
one or two disturbance activities can
dramatically reduce the impact of those
remaining. Simple changes in manage-
ment, such as the use of conservation
buffer strips in cropland or managed
livestock access to riparian areas, can
substantially overcome undesired
cumulative effects or synergistic
interactions.
3-26
Chapter 3: Disturbance Affecting Stream Corridors
-------
Table 3.3: Potential effects of major
land use activities.
Disturbance Activities
I
Homogenization of landscape elements
Point source pollution
Nonpoint source pollution
I
Dense compacted soil
Increased upland surface runoff
Increased sheetflow w/surface erosion
rill and gully flow
Increased levels of fine sediment and
contaminants in stream corridor
Increased soil salinity
Increased peak flood elevation
Increased flood energ
Decreased infiltration of surface runoff
t'
Decreased interflow and subsurface flow
Reduced ground water recharge and
aquifer volumes
Increased depth to ground water
Decreased ground water inflow to stream
Increased flow velocities
Reduced stream meander
Increased or decreased stream stability
Increased stream migration
Channel widening and downcutting
Increased stream gradient and reduced
energy dissipation
Increased or decreased flow frequency
Reduced flow duration
Decreased capacity of floodplain and
upland to accumulate, store, and filter
materials and energy
Increased levels of sediment and
contaminants reaching stream
Decreased capacity of stream to
accumulate and store or filter mate
and energy
Reduced stream capacity to assimilate
nutrients/pesticides
Confined stream channel w/little
opportunity for habitat development
Activity has potential for direct impact.
1 ! 1 | 1 1
m\ mm
3H[ 3H
Activity has potential for indirect impact.
Human-Induced Disturbances
3-27
-------
Table 3.3: Potential effects of major
land use activities (continued)
Disturbance Activities
Increased streambank erosion and
channel scour
Increased bank failure
Loss of instream organic matter and
related decomposition
Increased instream sediment, salinity,
and turbidity
Increased instream nutrient enrichment,
siltation, and contaminants leading to
eutrophication
Highly fragmented stream corridor with
reduced linear distribution of habitat
and edge effect
I
Loss of edge and interior habitat
Decreased connectivity and width within
the corridor and to associated ecosystems
Decreased movement of flora and fauna
species for seasonal migration, dispersal,
and population
Increase of opportunistic species,
predators, and parasites
Increased exposure to solar radiation,
weather, and temperature extremes
Magnified temperature and moisture
extremes throughout the corridor
Loss of riparian vegetation
Decreased source of instream shade,
detritus, food, and cover
Loss of vegetative composition, structure,
and height diversity
Increased water temperature
Impaired aquatic habitat diversity
Reduced invertebrate population in
stream
Loss of associated wetland function
including water storage, sediment
trapping, recharge, and habitat
Reduced instream oxygen concentration
Invasion of exotic species
uuu
E0000000B000B000000
1HSHBHHHS
JUuUUuLJL
]
.
IE
Reduced gene pool of native species for
dispersal and colonization
Reduced species diversity and biomass
Activity has potential for direct impact.
E[ 3H
SHHSHQ
Activity has potential for indirect impact.
3-28
Chapter 3: Disturbance Affecting Stream Corridors
-------
Developing
a Stream
Corridor
Restoration
Plan
Chapter 4: Getting Organized and
Identifying Problems and
Opportunities
Chapter 5: Developing Goals, Objectives,
and Restoration Alternatives
Chapter 6: Implement, Monitor, Evaluate,
and Adapt
A well conceived and developed stream
corridor restoration plan is critical to
any restoration effort. The restoration plan
establishes a framework for documenting
the processes, forms, and functions oper-
ating within the corridor, identifying dis-
turbances that disrupt or eliminate those
functions, and planning and implement-
ing restoration activities. The restoration
plan essentially serves as the cornerstone
of the restoration effort by achieving sev-
eral key functions.
m Problem Solving FrameworkThe
restoration plan establishes a frame-
work for addressing critical stream cor-
ridor restoration issues, problems, and
needs. As such, it prevents disjointed
decision-making and facilitates the
organization of restoration activities.
Documenting the Results of the
ProcessThe restoration plan serves
as a record of all sub-
sequent activities by
outlining the restora-
tion process. As a
result, the plan enables
-------
The restoration
plan should
emphasize the
maintenance
and restoration
of the ecological
integrity and
the dynamic
stability of the
stream corridor
by focusing on
multiple scales,
functions, and
values.
the transfer of "lessons learned"
to other groups undertaking
restoration efforts and helps
legitimize the restoration process.
m Communication and
OutreachThe restoration plan
serves to communicate the ele-
ments of the corridor restoration
process to the public and other
interested parties. It also serves
an important symbolic function
in that it represents the common
vision of multiple partners.
The overall objective of the restora-
tion plan will differ depending on
local needs and objectives. Each
corridor restoration initiative has
unique ecological, social, and eco-
nomic conditions that dictate activi-
ties to meet specific needs and
changing circumstances. Despite
these differences, the restoration
plan should emphasize the ecologi-
cal integrity of the stream corridor.
A Note About Scope
Although the concepts presented in
these chapters are appropriate for
all restoration initiatives, the organi-
zational structure can be simplified
for smaller restorations.
Not all restorations are complex or
costly. Some may be as simple as a
slight change in the way that re-
sources are managed in and along
the stream corridor involving only
minor costs. Other restoration ini-
tiatives, however, may require sub-
stantial funds because of the
implement,
monitor,
evaluate, and
adapt
.
develop
goals and
objectives
select and
design
restoration
alternatives
The Stream Corridor Restoration Plan
Development Process
complexity and extent of the mea-
sures needed to achieve the
planned restoration goals.
In recognition of the diversity of
restoration plan objectives, Part II of
the document focuses on identifying
and explaining a general restoration
plan development process that each
initiative should follow. This process
is characterized as a decision-
making process composed of several
steps (see illustration). These funda-
mental steps include: getting orga-
nized; identifying problems and
opportunities; developing goals and
objectives; selecting and designing
restoration alternatives; and imple-
mentation, monitoring, evaluation,
and adaptation.
Each of these steps can be inte-
grated into any program- or
agency-specific restoration planning
process. In addition, these steps
ll-ii
Part II: Developing a Stream Corridor Restoration Plan
-------
should not be viewed as sequential,
but iterative in nature. Many of the
fundamental steps may be repeated
or may occur simultaneously. In ad-
dition, the process, which is based
on the philosophy of adaptive man-
agement, should be flexible enough
to adjust management actions and
directions in light of new informa-
tion about the corridor and about
progress toward restoration
objectives.
Part II consists of three chapters
and is organized in accordance
with the fundamental steps of the
restoration plan development
process.
m Chapter 4 introduces the first
two steps of plan development.
The first portion of the chapter
focuses on the basics of getting
organized and presents key steps
that should be undertaken to ini-
tiate the restoration process. The
remainder of the chapter centers
on problem/opportunity identifi-
cation and introduces the basics
of stream corridor condition
analysis and problem assessment.
m Chapter 5 presents information
concerning how restoration goals
and objectives are identified and
how alternatives are designed
and selected.
m Chapter 6 concludes with a dis-
cussion of implementation of
restoration as well as monitoring
and evaluation.
Natural Disturbances ll-iii
-------
-------
Part II
(D
>
adapt!
managerl
^^ <
Developing A
Restoration
^^B ^^
Plan
echnical Team'
Researching anfrevak
Ilingoptions for the
toration
Advisory Tear
icowomic
Dncerns
8000
7000
3 6000
o 5000
VJ
£ 4000
o
" 3000
2000
0
-
-
.
D
C ° E
O O
- A B0 \
Fo
O cost effectiveness
frontier
i i i
0 80 100 120
Units of Output
1
14
= low accuracy
Watts Branch
-------
-------
Organized
and Identifying
Problems and
Opportunities
.,,....
>->>>
-------
4.A Getting Organized
Why is planning important?
Is an Advisory Group needed?
How is an Advisory Group formed?
Who should be on an Advisory Group?
How can funding be identified and acquired?
How are technical teams established and what are their roles?
What procedures should an Advisory Group follow?
How is communication facilitated among affected stakeholders?
4.B Problem and Opportunity Identification
Why is it important to spend resources on the problem ("When everyone already knows what
the problem is")?
How can the anthropogenic changes that caused the need for the restoration initiative be
altered or removed?
How are data collection and analysis procedures organized?
How are problems affecting the stream corridor identified?
How are reference conditions for the stream corridor determined?
Why are reference conditions needed?
How are existing management activities influencing the stream corridor?
How are problems affecting the stream corridor described?
-------
Getting
Organized and
Identifying
Problems and
Opportunities
4.A Getting Organized
4.B Problem and Opportunity
Identification
The impetus for a restoration initiative
may come from several sources. The
realization that a problem or opportunity
exists in a stream corridor may warrant
community action and any number of in-
terested groups, and individuals may be
actively involved in recognizing the situa-
tion and initiating the restoration effort.
Federal or state agencies may be desig-
nated to undertake a corridor restoration
effort as a result of a legislative mandate
or an internal agency directive. Citizen
groups or groups with special cultural or
economic interests in the corridor (e.g.,
native tribes, sport fishermen) may also
initiate a restoration effort. Still others
might undertake stream corridor restora-
tion as part of a broad-based cooperative
initiative that draws from various funding
sources and addresses a diversity of inter-
ests and objectives.
Accompanying the recognition of the situ-
ation and initiation of the restoration ef-
fort is the initial proposal of "the solution."
This almost instantaneous leap from
problem/opportunity recognition to the
identification of the initial "solution"
occurs during the formative stage of
nearly every initiative involving water and
multiple landowners. This instantaneous
leap might not always address the true
causes of the problem or identified oppor-
tunity and therefore might not result in a
-------
successful restoration initiative.
Projects that come through a logi-
cal process of plan development
tend to be more successful.
Regardless of the origins of the
restoration initiative or the intro-
duction of the proposed "solution,"
it is essential that the focus of the
leadership for the restoration plan-
ning process be at the local level;
i.e., the people who are pushing
for action, who own the land, who
are affected, who might benefit,
who can make decisions, or who
can lead. With this local leadership
in place, a logical, iterative restora-
tion plan development process can
be undertaken. Often, this ap-
proach will involve going back to
the identification of the problem or
opportunity and realizing that the
situation is not as simple as initially
perceived and needs further defini-
tion and refinement.
This chapter concentrates on the
two initial steps of stream corridor
restoration plan development-
getting organized and problem/
opportunity identification. The
chapter is divided into two sections
and includes a discussion of the
core components of each of these
initial steps.
Section 4.A: Getting Organized
This section outlines some of the
organizational considerations that
should be taken into account when
conducting stream corridor restora-
tion.
Section 4.B: Problem and
Opportunity Identification
Once some of the organizational
logistics have been settled, the dis-
turbances affecting the stream cor-
ridor ecosystem and the resulting
problems/opportunities need to be
identified. Section B outlines the
core components of the problem/
opportunity identification process.
One of the most common mistakes
made in planning restorations is the
failure to characterize the nature of
the problems to be solved and
when, where, and exactly how they
affect the stream corridor.
4-2
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
4.A Getting Organized
This section presents the key compo-
nents of organizing and initiating the
development of a stream corridor
restoration plan and establishing a
planning and management framework
to facilitate communication among all
involved and interested parties. Ensur-
ing the involvement of all partners and
beginning to secure their commitment
to the project is a central aspect of
"getting organized" and undertaking a
restoration initiative. (See Chapter 6 for
detailed information on securing com-
mitments.) It is often helpful to identify
a common motivation for taking action
and also to develop a rough outline of
restoration goals. In addition, defining
the scale of the corridor restoration ini-
tiative is important. Often the issues to
be addressed require that restoration be
considered on a watershed or whole-
reach basis, rather than by an individ-
ual jurisdiction or one or two
landholders.
Setting Boundaries
Geographical boundaries provide a spa-
tial context for technical assessment
and a sense of place for organizing
community-based involvement. An es-
tablished set of project boundaries
streamlines the process of gathering, or-
ganizing, and depicting information for
decision making.
When boundaries are selected, the area
should reflect relevant ecological
processes. The boundaries may also re-
flect the various scales at which ecologi-
cal processes influence stream corridors
(see Chapter 5, Identifying Scale Consid-
erations). For example, matters affecting
the conservation of biodiversity tend to
play out at broader, more regional
scales. On the other hand, the quality
of drinking water is usually more of a
basin-specific or local-scale issue.
In setting boundaries, two other factors
are equally as important. One is the na-
ture of human-induced disturbance, in-
cluding the magnitude of its impact on
stream corridors. The other factor is the
social organization of people, including
where opportunities for action are dis-
tributed across the landscape.
The challenge of establishing useful
boundaries is met by conceptually su-
perimposing the three selection factors.
One effective way of starting this
process is through the identification, by
public forum or other free and open
means, of a stream reach or aquatic re-
source area that is particularly valued by
the community. The scoping process
would continue by having resource
managers or landowners define the geo-
graphical area that contributes to both
the function and condition of the val-
ued site or sites. Those boundaries
FAST
FORWARD
REVERSE
Review Chap-
ter 1. Preview
Chapter 5's
Identifying
Scale Consider-
ations.
Core Components of Getting Organized
Setting boundaries
Forming an advisory group
Establishing technical teams
Identifying funding sources
Establishing points of contact and a decision structure
Facilitating involvement and information sharing among
participants
Documenting the process
Getting Organized
4-3
-------
Forming an ad-
visory group is
an effective
and efficient
way to plan
and manage
the restoration
effort, al-
though not all
restoration de-
cision makers
will choose to
establish one.
would then be further adjusted to re-
flect community interests and goals.
Forming an Advisory Group
Central to the development of a stream
corridor restoration plan is the forma-
tion of an advisory group (Figure 4.1).
An advisory group is defined as a col-
lection of key participants, including
private citizens, public interest groups,
economic interests, public officials, and
any other groups or individuals who are
interested in or might be affected by the
restoration initiative. Grassroots citizen
groups comprise multiple interests that
hopefully share a stated common con-
cern for environmental conservation.
Such broad-based participation helps
ensure that self-interest or agency agen-
das do not drive the process from the
top down. Local citizens should be en-
listed and informed to the extent that
their values and preferences drive deci-
sion making with technical guidance
from agency participants.
Figure 4.1: Advisory group meeting. The advi-
sory group, composed of a variety of communi-
ty interests, plays an active role in advising the
decision maker(s) throughout the restoration
process.
Source: S. Ratcliffe. Reprinted by permission.
The advisory group generally meets for
the following purposes:
Carrying out restoration planning
activities.
Coordinating plan implementation.
Identifying the public's interest in the
restoration effort.
Making diverse viewpoints and
objectives known to decision makers.
Ensuring that local values are taken
into account during the restoration
process.
The point to remember is that the true
role of the advisory group is to advise
the decision maker or sponsorthe
agency(s), organization(s), or individ-
ual^) leading and initiating the restora-
tion efforton the development of the
restoration plan and execution of
restoration activities. Although the advi-
sory group will play an active planning
and coordinating role, it will not make
the final decisions. As a result, it is im-
portant that all members of the advi-
sory group understand the issues,
develop practical and well thought-out
recommendations, and achieve consen-
sus in support of their recommenda-
tions.
Typically, it is the responsibility of the
decision maker(s) to identify and orga-
nize the members of the advisory
group. Critical to this process is the
identification of the key participants.
Participants can be identified by mak-
ing announcements to the news media,
writing to interested organizations,
making public appearances, or directly
contacting potential partners.
The exact number of groups or individ-
uals that will compose the advisory
group is difficult to determine and is
usually situation-specific. In general, it
is important that the group not be so
small that it is not representative of all
4-4
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
interests. Exclusion of certain commu-
nity interests can undermine the legiti-
macy of or even halt the restoration
initiative. Conversely, a large group
might include so many interests that or-
ganization and consensus building be-
come unmanageable. Include a balance
of representative interests such as the
following:
Private citizens
Public interest groups
Public officials
Economic interests
It is important to note that while form-
ing an advisory group is an effective
and efficient way to plan and manage
the restoration effort, not all restoration
decision makers will choose to establish
one. There might be cases where a
landowner or small group of landown-
ers elect to take on all of the responsi-
bilities of the advisory group in
addition to playing a leadership or
decision-making role.
Regardless of the number of individuals
involved, it is important for all project
participants (and funders) to note at
this early stage that the usual duration
of projects is 2 to 3 years. There are no
guarantees that every project will be a
success, and in some cases a project
may fail simply due to lack of time to
allow nature to "heal itself" and restora-
tion methods to take effect. All partici-
pants must be reminded up front to set
realistic expectations for the project and
for themselves.
Establishing Technical Teams
Planning and implementing restoration
work requires a high level of knowl-
edge, skill, and ability, as well as profes-
sional judgment. Often, the advisory
group will find it necessary to establish
special technical teams, or subcommit-
tees, to provide more information on a
particular issue or subject.
In general, interdisciplinary technical
teams should be organized to draw
upon the knowledge and skills of differ-
ent agencies, organizations, and indi-
viduals. These teams can provide
continuity as well as important infor-
mation and insight from varied disci-
plines, experiences, and backgrounds.
The expertise of an experienced multi-
disciplinary team is essential. No single
text, manual, or training course can
provide the technical background and
judgment needed to plan, design, and
implement stream corridor restoration.
A team with a broad technical back-
ground is needed and should include
expertise in both engineering and bio-
logical disciplines, particularly in
aquatic and terrestrial ecology, hydrol-
ogy, hydraulics, geomorphology, and
sediment transport.
Team members should represent inter-
agency, public, and private interests and
include major partners, especially if
they are sharing costs or work on the
restoration initiative. Team makeup is
based on the type of task the team is as-
sembled to undertake. Members of the
technical teams can also be members of
the advisory committee or even the
decision-making body.
Some of the technical teams that could
be formed to assist in the restoration
initiative will have responsibilities such
as these:
Soliciting financial support for the
restoration work.
Coordinating public outreach.
Providing scientific support for the
restoration work. This support may
encompass anything from conduct-
ing the baseline condition analysis to
designing and implementing restora-
tion measures and monitoring.
Getting Organized
4-5
-------
Y Lower Missouri River Coordinated
Resource Management Efforts in
Northeast Montana
The Lower Missouri River Coordinated Resource
Management (CRM) Council is an outgrowth
of the Lower Fort Peck Missouri River Development
Group, which was formed in September 1990 as a
result of an irrigation and rural development meet-
ing held in Poplar, Montana. The meeting was held
to determine the degree of interest in economic
and irrigation development along the Missouri
River below Fort Peck Dam.
A major blockade to development seemed to be
the erosion problems along the river. The Roosevelt
County Conservation District and other local lead-
ers decided that before developing irrigation along
the river, streambank erosion needed to be
addressed.
The large fluctuation of the water being released
from Missouri River dams is causing changes in the
downstream river dynamics, channel, and stream-
banks. Before the dams, the river carried a sedi-
ment load based on the time of the year and flow
event. Under natural conditions, a river system
matures and tries to be in equilibrium by transport-
ing and depositing sediment. Today, below the
dams, the water is much cleaner because the sedi-
ment has settled behind the dams (Figure 4.2).
The clean water releases have changed the river
system from what it was prior to the dams. The
clean water now picks up sediment in the river
and attacks the streambanks, while trying to reach
equilibrium. These probable causes and a river sys-
tem out of equilibrium could be part of the cause
of the river erosion.
Figure 4.2: Lower Missouri River. Water released from dams is causing downstream erosion.
4-6
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
Leaders in the group are politically active, traveling
to Washington, D. C., and meeting with congres-
sional delegates and the US Army Corps of
Engineers (USACE) to secure funding to address
streambank erosion. As a result of the trips to
Washington, $3 million was appropriated and
transferred to the US ACE for streambank erosion
abatement. However, efforts to agree on a mutual-
ly beneficial solution continued to delay the
progress. The US ACE had completed an economic
analysis of the area, and the only viable alternative
it could offer was sloughing easements. This
would do little to save the valuable soils along the
Missouri River.
The group seemed to be at a stalemate. In July
1994, then Chief of the Natural Resources
Conservation Service (NRCS), Paul Johnson, met
with the members of the Lower Fort Peck Missouri
River Development Group, local landowners, sur-
rounding Conservation District members, NRCS
field office staff, and Bill Miller, Project Manager
for the Omaha District of the USACE, at an erosion
site along the Missouri River. After sharing of ideas
and information, Chief Johnson suggested that a
Coordinated Resource Management (CRM) group
be formed to resolve the sensitive issues surround-
ing the erosion and other problems of the river. He
instructed local and state NRCS staff to provide
technical assistance to the CRM group. The group
followed Chief Johnson's idea, and the Lower
Missouri River CRM Council was formed. This has
helped those involved in solving the problems to
overcome many of the stumbling blocks with
which they were being confronted. Some of these
successes include:
Through the CRM Council the $3 million trans-
ferred to the USACE was used to try some new
innovative erosion solutions on a site in Montana
and one in North Dakota. The group helped the
USACE to select the site. NRCS assisted in the
design and implementation. For the first time in
this area, materials such as hay bales, willow cut-
tings, and log revetments were used.
An interagency meeting and tour of erosion sites
was sponsored by the CRM Council in
September of 1996. In addition to local produc-
ers, CRM Council members, NRCS state and
national staff, USACE staff, researchers from the
USDA Agricultural Research Service (ARS)
National Sedimentation Laboratory of Oxford,
Mississippi, attended the session. The group
agreed that the erosion problem needed to be
studied further. The NRCS, USACE, and ARS have
been doing studies on the River System below
Fort Peck Dam since the 1996 meeting. A final
report on the research is planned for summer of
1998.
The CRM Council has been surveying producers
along the river to determine what they perceive
to be their major problems. This helps the group
to stay in tune with current problems.
The CRM Council contracted with a group of
Montana State University senior students from
the Film and TV Curriculum to develop an infor-
mational video about the Missouri River and its
resources. This project has been completed, and
the video will be used to show legislators and
others what the problems and resources along
the river are.
The group has been successful because of the
CRM process. The process takes much effort by all
involved, but it does work.
Getting Organized
4-7
-------
CASESWDY Watershed Planning Through a
^^^ vT^T ^^ Coordinated Resource Manaaei
/^
Coordinated Resource Management
Planning Process
The American River watershed, located in the
Sierra Nevada Mountains of California, com-
prises 963 square miles. It is an important source
of water for the region. The watershed also sup-
ports a diversity of habitats from grassland at
lower elevations, transitioning to chaparral and to
hardwood forest, and eventually to coniferous for-
est at upper elevations. In addition, the watershed
is a recreational and tourist destination for the
adjacent foothill communities like the greater
Sacramento metropolitan area and the San
Francisco Bay area.
Urban development is rapidly expanding in the
watershed, particularly at lower elevations. This
additional development is challenging environ-
mental managers in the watershed and stressing
the natural resources of the area. In 1996, the
Placer County Resource Conservation District
(PCRCD) spearheaded a multi-interest effort to
address watershed concerns within the American
River watershed. Due to the range of issues to be
addressed, they sought to involve representatives
from various municipalities, environmental and
recreational groups, fire districts, ranchers, and
state and federal agencies. The group established
a broad goal "to enhance forest health and the
overall condition of the watershed," as well as a
set of specific goals that include the following:
Actively involve the community and be respon-
sive to its needs.
Optimize citizen initiative to manage fuels on pri-
vate property to enhance forest and watershed.
Restore hydrologic and vegetative characteristics
of altered meadows and riparian areas.
Create and sustain diverse habitats supporting
diverse species.
Ensure adequate ground cover to prevent silta-
tion of waterways.
Reduce erosion from roads and improvements.
Prevent and correct pollution discharges before
they adversely affect water quality.
Reduce excessive growths of fire-dependent
brush species.
Increase water retention and water yield of the
watershed.
Optimize and sustain native freshwater species.
Because of past conflicts and competing interests
among members of the group, a Memorandum of
Understanding (MOU) was prepared to develop a
cooperative framework within which the various
experts and interest groups could participate in
natural resource management of the watershed.
The signatories jointly committed to find common
ground from which to work. The first step was to
establish "future desired conditions" that will meet
the needs of all the signatories as well as the local
landowners and the public.
By including all of the signatories in the prioritiza-
tion of implementation actions, PCRCD continues to
keep the watershed planning process moving for-
ward. In addition, PCRCD has encouraged the
development of a small core group of landowners,
agency representatives, and environmental organi-
zations to determine how specific actions will be
implemented. Several projects that incorporate
holistic ecosystem management and land steward-
ship principles to achieve measurable improvements
within the watershed are already under way.
4-8
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
Investigating sensitive legal, econom-
ic, or cultural issues that might influ-
ence the restoration effort.
Facilitating the restoration planning,
design, and implementation process
outlined in this document.
It is important to note that technical ex-
pertise often plays an important role in
the success of restoration work. For ex-
ample, a restoration initiative might in-
volve resource management or land use
considerations that are controversial or
involve complex cultural and social is-
sues. An initiative might address issues
like western grazing practices or water
rights and require the restriction of cer-
tain activities, such as timber or mineral
extraction, certain farming and grazing
practices, or recreation (Figure 4.3). In
these cases, involving persons who have
the appropriate expertise on regulatory
programs, as well as social, political,
and legal issues, can prevent derailment
of the restoration effort.
Perhaps the most important benefit of
establishing technical teams, however, is
that the advisory group and decision
makers will have the necessary informa-
tion to develop restoration objectives.
The advisory group will be able to inte-
grate the knowledge gained from the
analysis of what is affecting stream cor-
ridor structure and functions with the
information on the social, political, and
economic factors operative within the
stream corridor. Essentially, the advisory
group will be able to help define a thor-
ough set of restoration objectives.
Identifying Funding Sources
Identifying funding sources is often an
early and vital step toward an effective
stream restoration initiative. The fund-
ing needed may be minimal or substan-
tial, and it may come from a variety of
sources. Funding may come from state
or federal sources that have recognized
Interdisciplinary Nature of Stream
Corridor Restoration
777e complex nature of stream corridor restoration
requires that any restoration initiative be approached
from an interdisciplinary perspective. Specialists from a
variety of disciplines are needed to provide both the
advisory group and sponsor with valuable insight on sci-
entific, social, political, and economic issues that might
affect the restoration effort. The following is a list of
some of the professionals who can provide important
input for this interdisciplinary effort:
Foresters
Legal consultants
Botanists
Microbio/ogists
Engineers
Hydrologists
Economists
Geomorphologists
Archaeologists
Sociologists
Soil scientists
Rangeland specialists
Landscape architects
Fish and wildlife biologists
Public involvement
specialists
Real estate experts
Ecologists
Native Americans and
Tribal Leaders
the need for restoration due to the ef-
forts of local citizens' groups. Funding
may come from counties or any entity
that has taxing authority. Philanthropic
organizations, nongovernmental orga-
nizations, landowners' associations, and
voluntary contributions are other fund-
ing sources. Regardless of the source of
funds, the funding agent (sponsor) will
almost certainly influence restoration
decisions or act as the leader and deci-
sion maker in the restoration effort.
Getting Organized
4-9
-------
Figure 4.3: Livestock grazing. Technical teams
can be helpful in addressing controversial and
complex issues that have the potential to influ-
ence the acceptance and success of a restora-
tion initiative.
Establishing a Decision
Structure and Points of
Contact
Once the advisory group and relevant
technical teams have been formed, it is
important to develop a decision-making
structure (Figure 4.4) and to establish
clear points of contact.
As noted earlier, the advisory group will
play an active planning and coordinat-
ing role, but it will not make the final
decisions. The primary decision-making
authority should reside in the hands of
the stakeholders. The advisory group,
however, will play a strong role by pro-
viding recommendations and inform-
ing the decision maker(s) of various
restoration options and the opinions of
the various participants.
It is important to note that the decision
maker, as well as the advisory group,
may be composed of a collection of in-
terests and organizations. Conse-
quently, both entities should establish
some basic protocols to facilitate deci-
sion making and communication.
Within each group some of the follow-
ing rules of thumb might be helpful:
Select officers
Establish ground rules
Establish a planning budget
Appoint technical teams
In conjunction with establishing a deci-
sion structure, the sponsor, advisory
group, and relevant subcommittees
need to establish points of contact.
These points of contact should be peo-
ple who are accessible and possess
strong outreach and communication
skills. Points of contact play an impor-
tant role in the restoration process by
facilitating communication among the
various groups and partners.
Facilitating Involvement and
Information Sharing Among
Participants
It is important that every effort be made
to include all interested parties
throughout the duration of the restora-
tion process. Solicit input from partici-
pants and keep all interested parties
informed of the plan development, in-
cluding uncertainties associated with a
particular solution, approach, or man-
agement prescription and what must be
involved in modifying and adapting
them as the need arises. In other words,
it is important to operate under the
principles of both information giving
and information receiving.
Receiving Input from Restoration
Participants
In terms of information receiving, a
special effort should be made to di-
rectly contact landowners, resource
users, and other interested parties to ask
them to participate in the planning
process. Typically, these groups or indi-
4-10
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
Decision Maker
Responsible for organizing the advisory
group and for leading the stream corridor
restoration initiative. The decision maker
can be a single organization or a group of
individuals or organizations that have
formed a partnership. Whatever the case
it is important that the ^, ^
restoration effort be
locally led.
Technical Team
Researching and evaluating
funding options for the
stream corridor restoration
initiative.
Technical Team
Analyzing condition
of stream corridor
structure and
functions.
Advisory Group
Provides consensus-based
recommendations to the
decision maker based upon
information from the
technical teams and input
from all participants.
Technical Team
Analyzing economic
issues and concerns
relevant to the stream
corridor restoration
initiative.
Technical Team
Analyzing social and
cultural issues and
concerns relevant to the
stream corridor
restorative initiative.
Technical Team
Coordinating public
outreach efforts and
soliciting input from
interested participants.
Figure 4.4: Flow of communication. Restoration plan development requires a decision structure
that streamlines communication between the decision maker, the advisory group, and the various
technical teams.
viduals will have some personal interest
in the condition of the stream corridor
and associated ecosystems in their re-
gion. A failure to provide them the op-
portunity to review and comment on
stream corridor restoration plans will
often result in objections later in the
process.
Private landowners, in particular, often
have the greatest personal stake in the
restoration work. As part of the restora-
tion effort it might be necessary for pri-
vate landowners to place some of their
assets at increased risk, make them
more available for public use, or reduce
the economic return they provide (e.g.,
restricting grazing in riparian areas or
increasing buffer widths between agri-
cultural fields and drainage channels).
Thus, it is in the best interest of the
restoration initiative to include these
persons as decision makers.
A variety of public outreach tools can
be useful in soliciting input from partic-
ipants. Some of the most common
mechanisms include public meetings,
workshops, and surveys. Took for Facili-
tating Participant Involvement and Infor-
mation Sharing During the Restoration
Process, provides a more complete list of
potential outreach options.
Getting Organized
4-11
-------
Informing Participants
Throughout the Restoration
Process
In addition to actively seeking input
from participants, it is important that
the sponsor(s) and the advisory group
regularly inform the public of the status
of the restoration effort. The restoration
initiative can also be viewed as a strong
educational resource for the entire com-
munity. Some effective ways to commu-
nicate this information and to provide
educational opportunities include
newsletters, fact sheets, seminars, and
brochures. A more complete list of po-
tential outreach tools is provided in the
box Took for Facilitating Participant In-
Tools for Facilitating Participant
Involvement and Information Sharing
During the Restoration Process
Tools for Receiving
Input
Public Hearings
Task Forces
Training Seminars
Surveys
focus Groups
Workshops
Interviews
Review Groups
Referendums
Phone-in Radio Programs
Internet Web Sites
Tools for Informing
Participants
Public Meetings
Internet Web Sites
Fact Sheets
News Re/eases
Newsletters
Brochures
Radio or TV Programs
or Announcements
Telephone Hotlines
Report Summaries
Federal Register
volvement and Information Sharing Dur-
ing the Restoration Process.
It is important to note that the educa-
tional opportunities associated with in-
formation giving can help support
restoration initiatives. For example, in
cases that require the implementation of
costly management prescriptions, out-
reach tools can be effective in improving
landowner awareness of ways in which
risks and losses can be offset, such as
incentive programs (e.g., Conservation
Reserve Program) or cost-sharing proj-
ects (e.g., Section 319 of the Clean
Water Act). In these cases, the most
effective approach might be for the
representative landowners serving on
the decision-making team to be respon-
sible for conducting this outreach to
their constituents.
In addition, educational outreach can
also be viewed as an opportunity to
demonstrate the anticipated benefits of
restoration work, on both regional and
local levels. One of the most effective
ways to accomplish this is with periodic
public field days involving visits to the
restoration corridor, as well as pilot
demonstration sites, model farms, and
similar examples of restoration actions
planned.
Finally, wherever possible, information
on the effectiveness and lessons learned
from restoration work should be made
available to persons interested in carry-
ing out restoration work elsewhere.
Most large restoration initiatives will re-
quire relatively detailed documentation
of design and performance, but this in-
formation is usually not widely distrib-
uted. Summaries of restoration
experiences can be published in any of
a variety of technical journals, newslet-
ters, bulletins, Internet Web sites, or
other media and can be valuable to the
success of future restoration initiatives.
4-12
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
Selecting Tools for Facilitating
Information Sharing and
Participant Involvement
Although a variety of outreach tools can
be used to inform participants and so-
licit input, attention should be paid to
selecting the best tool at the most ap-
propriate time. In making this selection,
it is helpful to consider the stage of the
restoration process as well as the out-
reach objectives.
For example, if a restoration initiative is
in the early planning stages, providing
community members with background
information through a newsletter or
news release might be effective in bring-
ing interested parties to the table and in
generating support for the initiative
(Figures 4.5 and 4.6). Conversely, once
the planning process is well under way
and restoration alternatives are being
selected, a public hearing may be a use-
CBF NEWS
Oyster Plan Falls Short
on Conservation
Ikf Bey at numfrni jufficicni ntptrmii lutreitneutl tiamaiag, rtr
Richmond Times- DutoKb edilorill
As
September 23 hearing. the Virginia Marine Resources
Ttast rrxtfislifnscrling! netted by a CSF
lera in favor of lightened halves! restrictions.
nomk as iwll i. Ixotogiol factors. However, if a fish population
is so depleted thai is existence is Unentered. Ihe socio-economic
benefrts will be lest entirely if drastic measures ire not taken.
aggressive program to rebuild oyster habitat is the surest way 10
bring about recovery. The recommendation before the commis-
sion UK J to accommodate Ihe industry by leaving [he public seed
CBF supported skit proposal because it addrt ised (he important
objective or conservkiE adult oysters as brood slock.
Rockfish Rebound Affirms
Management Controls
Chesapeate Bay demonst
annual sniped basi juvenile surveys in Maryland and
Virginia yielded "young-of rhe.yea" indict* of 39.6 and 18.1
foot seine net. The previous highs were J0.4 in Maiylwid. taken
UlL-
U987 in
Fjiunitts indicate that the oyster population in Virginia hat
declined more than ten-fold since the mid-1980s. The harvest of
replanted in other was) run declined by a similar rate during Ihe
period, leaving link doubt thai fewer seed are being produced
when aher ira berime depleted, watermen nocked to the Janes
sndl*j»tui»Mringm»rk«:iiKdoyslers. Arteianincraisethe
first year, the harvest declined .Iradilv to MI ill time low last year.
has taken place primarily between fall and Srr Orstera page g
Figure 4.5: Chesapeake Bay Foundation
newsletter. Newsletters can be an effective
way to communicate the status of restoration
efforts to the community.
ful mechanism for receiving input on
the desirability of the various options
under consideration (Figure 4.7).
Some additional factors that should be
taken into account in selecting outreach
tools include the following:
Strengths and weaknesses of individ-
ual techniques.
Cost, time, and personnel required
for implementation.
Receptivity of the community.
Again, no matter what tools are se-
lected, it is important to make an effort
to solicit input from participants as well
as to keep all interested parties in-
formed of plan developments. The In-
teragency Ecosystem Management Task
Force (1995) provides the following
suggestion for a combination of tech-
niques that can be used to facilitate par-
ticipant involvement and information
sharing:
Regular newsletters or information
sheets apprising people of plans and
progress.
Regularly scheduled meetings of
landowner and citizen groups.
Public hearings.
Field trips and workdays on project
sites for volunteers and interested
parties.
In addition, the innovative communica-
tion possibilities afforded by the Inter-
net and the World Wide Web cannot be
ignored.
Documenting the Process
The final element of getting organized
involves the documentation of the vari-
ous activities being undertaken as part
of the stream corridor restoration effort.
Although the restoration plan, when
completed, will ultimately document
the results of the restoration process, it
Preview
Chapter 6's
Developing a
Monitoring
Plan.
Getting Organized
4-13
-------
SJ Press Releases
-V»* it Jim frdsai * (iivwtww
GOVERNOR SIGNS AGREEME>T WITH USDA TO PROVIDE M59
MILLION FOR LOW^-TERM PROGRAM TO RESTORE AND PRESERVE
ILLINOIS RIVER WATERSHED
PEORIA. ILL. -- Gov. Jim Edgar today signed an agreement with Ihe V. S.
Department of AgriCLiliUrt.'on i M?<3 rr.ill en miiurive iu n-*lore and preserve Itic
Illinois River waierUied. induJmg nc^surct lo reduce soil erosion and
icihmental ion. improve uniier^uiil11^. ami enhance wildlife hahita'.
"Restoring and protecting the IIlino« River Basin is of enormous environmental and
economic importance in the >iuie and the nation," the Governor said. This unique
partnership involves ihe voluntary participjt]e *ill combine elements of the USDA'S Conservation Reserve
ouni^cs landowners lo slop farming their mosl credible land.
lo n-hiorc m-tlands and plant trees and grasses lo improve the
Program, w
"Today's jgrcement is n tremendous step forward m our el'fwrts (o save the and wafer
rc'wurccs ol the Illinois Kiver Valley." kaid Ll. Gov. Bob Kuslra. who has led Ihe
Edgar adminisiraiion'sctrort1' to impmva the Illinois River. "Oy preventing millions
of tons af valuable tupwil from washing away, landowners who participate in this
innovative program will help keep Ihe river Open for comnwice and make backwater
lakes and streams viuhle for wildlife and recreation '
To achieve the goal oi reducing sedimentation in Ihe Illinois River by 20 pereenU
incentives are Ijrgeled lo owners of the mosterodibk land in V) counties with high
watershed ann jjlly. witn more than half of it deposited m llv Illinois River.
If the projected total of 232.000 acres are enrolled in the lllinnn Conservation
Reserve Enhancement Program, the financial o'llisalioii would be nearly J4S9
million over 15 years, including 1367 million in USDA fill Kb and 192 million in
slate funds.
Ihe mow acreage. U. S. Secretary of Agriculture Dan Qlicknwn was inPcona
Monday to ,>ign the agmcinvm with Edgar.
"This program provides the funds to ««are mofe of the floodplam forests, marshes
mid buffer zones around a river ihan any program in the nation's history," 5nid Fred
Krupp. Executive Director of the Environmental Defense Fund, "ft can remake the
Illinois River as one of the country's greatest natural resources."
"This important program is a voluntary, incetilive-based program designed \a assist
landowners in taking environmentally sensitive land out of agricultural production,"
said Ron Warfield, President of ihe Illinois Farm Bureau. "Programs like mis have
proven lo be posilive ways to address natural resources issues.1
Edgar and Kostra first proposed Ihe scale-federal partnership a year ago ['reserving
und improving the Illinois River waurshed, which contains nearly half of the
half of the commercial traffic on the Mississippi River above St. Louis uses the
Illinois River," Edgar said. "We must keep thai traffic flowing as we improve Ihe
environment of the watershed and increase recreational oppomini!ies on the river.
This initiative recognizes thai we all have a part to play in saving ihis river For future
general*."
In 1993, Kusira footwd (he RiverWatch network of volunteers to monilor the health
of rivers and streams acres* Hie state. Kustra also established a River Strategy Torn
bringing diverse interests to Ihe same table to discuss what was needed to improve
the Illinois River.
A year ago ihe S^ategy Team, with the help of moie lhan 100 volunteers from
business, conserve ion and agriculture, published the Integrated Management Plan
for Ihe Illinois River, including 34 wcommenditions for improving the watershed.
I . I,-, i also signed :tj(islaiion creating the Illinois Rivet Coordinating Council,
composed of agency heads and private citizens who will monitor the progress of Ihe
Illinois Conservation Reserve Enhancement Program and recommend other ways
MIL government can help enhance the watershed.
"The Illinois River is in a recovery mage," Kusua said. "A( [he birth of oui state in
1818, the watershed was a prisline paradise. But over time, polluting induslncs, poor
fanning practices and urbanization nearly choked and destroyed this mighty rivei.
"Eventually, the people came 10 the river's lid Today, we have restrictionE on
discharges by factories and cities, many farmers follow sound conservation practices,
Farmeis and landowners can get more information about the prugrwn froi
USDA Service Center office*. Farm Service Agency offices, (he NWursl.
Conservation Service, or from the Illinois Department of Natural RBBOUK
Figure 4.6: Regional restoration news releases.
A news release is an effective tool for inform-
ing the community of the planning of the
restoration initiative.
Source: State of Illinois.
is also important to keep track of activi-
ties as they occur.
An effective way to identify important
restoration issues and activities as well
as keep track of those activities is
through the use of a "restoration
checklist" (National Research Council,
1992). The checklist can be maintained
by the advisory group or sponsor and
used to engage project stakeholders and
to inform them of the progress of
restoration efforts. The checklist can
serve as an effective guide through the
remaining components of restoration
plan development and project imple-
mentation. In addition, a draft version
of Developing a Monitoring Plan (see
Chapter 6) should be prepared as part
of planning data collection.
Figure 4.7: Local public hearing. Public hearings
are a good way to solicit public input on
restoration options.
Source: S. Ratcliffe. Reprinted by permission.
4-14
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
Restoration Checklist (Adapted from National Research Council 1992)
During Planning...
Q Have all potential participants been informed of
the restoration initiative?
Q Has an advisory committee been established?
Q Have funding sources been identified?
Q Has a decision structure been developed and points
of contact identified?
Q Have steps been taken to ensure that participants
are included in the restoration processes?
Q Has the problem that requires treatment been
investigated and defined?
Q Has consensus been reached on the mission of the
restoration initiative?
Q Have restoration goals and objectives been identi-
fied by all participants in the restoration effort?
Q Has the restoration been planned with adequate
scope and expertise?
Q Has the restoration plan had an annual or mid-
course correction point in line with adaptive man-
agement procedures?
Q Have the indicators of stream corridor structure
and function been directly and appropriately linked
to the restoration objectives?
Q Have adequate monitoring, surveillance, manage-
ment, and maintenance programs been specified
as an integral part of the restoration plan? Have
monitoring costs and operational details been inte-
grated so that results will be available to serve as
input in improving techniques used in the restora-
tion work?
Q Has an appropriate reference system (or systems)
been selected from which to extract target values
of performance indicators for comparison in con-
ducting the evaluation of the restoration initiative?
Q Have sufficient baseline data been collected over a
suitable period of time on the stream corridor and
associated ecosystems to facilitate before-and-after
treatment comparisons?
Q Have critical restoration procedures been tested on
a small experimental scale to minimize the risks of
failure?
Q Has the length of a monitoring program been
established that is sufficiently long to determine
whether the restoration work is effective?
Q Have risk and uncertainty been adequately consid-
ered in planning?
Q Have alternative designs been formulated?
Q Have cost-effectiveness and incremental cost of
alternatives been evaluated?
During Project Implementation and Management...
Q Based on the monitoring result, are the anticipated
intermediate objectives being achieved? If not, are
appropriate steps being taken to correct the prob-
lem(s)?
Q Do the objectives or performance indicators need
to be modified? If so, what changes might be
required in the monitoring program?
Q Is the monitoring program adequate?
During Postrestoration...
Q To what extent were restoration plan objectives
achieved?
Q How similar in structure and function is the
restored corridor ecosystem to the reference
ecosystem?
Q To what extent is the restored corridor self-
sustaining (or will be), and what are the mainte-
nance requirements?
Q If all stream corridor structure and functions were
not restored, have the critical structure and func-
tions been restored?
Q How long did the restoration initiative take?
Q What lessons have been learned from this effort?
Q Have those lessons been shared with interested
parties to maximize the potential for technology
transfer?
Q What was the final cost, in net present value terms,
of the restoration work?
Q What were the ecological, economic, and socia
benefits realized by the restoration initiative?
Q How cost-effective was the restoration initiative?
Q Would another approach to restoration have pro-
duced desirable results at lower cost?
Getting Organized
4-15
-------
4.B Problem and Opportunity Identification
FAST
FORWARD
Preview
Chapter 7's
Data Collection
and Analysis
Methods
sections.
Development of stream corridor
restoration objectives is preceded by an
analysis of resource conditions in the
corridor. It is also preceded by the for-
mulation of a problem/opportunity
statement that identifies conditions to
be improved through and benefit from
restoration activities. Although prob-
lem/opportunity identification can be
very difficult, in terms of measurable
stream corridor conditions, it is the sin-
gle most important step in the develop-
ment of the restoration plan and in the
restoration process. This section focuses
on the six steps of the problem/oppor-
tunity identification process that are
critical to any stream corridor restora-
tion initiative.
The Six Steps of the Problem/
Opportunity Identification Process
1. Data collection and analysis
2. Definition of existing stream corridor conditions
(structure and function) and causes of disturbance
3. Comparison of existing conditions to desired condi-
tions or a reference condition
4. Analysis of the causes (disturbances) of altered or
impaired stream corridor conditions
5. Determination of how management practices might
be affecting stream corridor structure and functions
6. Development of problem and opportunity statements
Data Collection and Analysis
Data collection and analysis are impor-
tant to all aspects of decision making
and are conducted throughout the dura-
tion of the restoration process. The same
data and analytic techniques are often
applied to, and are important compo-
nents of, problem/opportunity identifi-
cation; goal formulation; alternative
selection; and design, implementation,
and monitoring. Data collection and
analysis, however, begin with problem/
opportunity identification. They are
integral to defining existing stream corri-
dor and reference conditions, identify-
ing causes of impairment, and
developing problem/opportunity state-
ments. Data collection and analysis
should be viewed as the first step in
this process.
Data Collection
Data collection should begin with a
technical team, in consultation with the
advisory group and the decision maker,
identifying potential data needs based
on technical and institutional require-
ments. The perspective of the public
should then be solicited from partici-
pants or through public input forums.
Data targeted for collection should gen-
erally provide information on both the
historical and baseline conditions of
stream corridor structure and functions,
as well as the social, cultural, and eco-
nomic conditions of the corridor and
the larger watershed.
Data are collected with the help of a
variety of techniques, including remote
sensing, historical maps and pho-
tographs, and actual resource inventory
using standardized on-site field tech-
niques, evaluation models, and other
recognized and widely accepted
4-16
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
methodologies. Community mapping
(drawing areas of importance to the
community or individuals) is becoming
a popular method of involving the
public and children in restoration
initiatives. This technique can solicit
information not accessible to tradi-
tional survey or data collection tech-
niques and it also makes the data
collection process accessible to the pub-
lic. Additional data collection and
analysis methods are discussed in
Part III, Chapter 7.
Collecting Baseline Data
Restoration work should not be at-
tempted without having knowledge of
existing stream corridor conditions. In
fact, it is impossible to determine goals
and objectives without this basic infor-
mation. As a result, it is important to
collect and analyze information that
provides an accurate account of existing
conditions. Due to the dynamic nature
of hydrologic systems, a range of condi-
tions need to be monitored. Ultimately,
these baseline data will provide a point
from which to compare and measure
future changes.
Baseline data consist of the existing
structure and functions of the stream
corridor and surrounding ecosystems
across scales, as well as the associated
disturbance factors. These data, when
compared to a desired reference condi-
tion (derived from either existing condi-
tions elsewhere in the corridor or
historical conditions), are important in
determining cumulative effects on the
stream corridor's structure and func-
tions (i.e., hydrologic, geomorphic,
habitat, etc.). Baseline data collection
efforts should include information
needed to determine associated prob-
lems and opportunities to be addressed
in later design and implementation
stages of the restoration process.
Collecting Historical Data
As described in earlier chapters, stream
corridors change over time in response
to ongoing natural or human-induced
processes and disturbances. It is impor-
tant to identify historical conditions
and activities to understand the present
stream corridor condition (Figure 4.8).
Figure 4.8: The Winooski River (a) in the 1930s
and (b) at the same location in the 1990s.
Using photographs is one way to identify the
historical condition of the corridor.
Problem and Opportunity Identification
4-17
-------
Part of collecting historical data is col-
lecting background information on the
requirements of the species and eco-
systems of concern. Historical data
should also include processes that oc-
curred at the site. The historic descrip-
tion may also be used to establish
target conditions, or the reference con-
dition, for restoration. Often the goal
of restoration will not be to return a
corridor to a pristine, or pre-European
settlement, condition. However, by un-
derstanding this condition, valuable
knowledge is gained for making deci-
sions on restoring and sustaining a
state of dynamic equilibrium.
In terms of gathering historical data,
emphasis should be placed on under-
standing changes in land use, channel
planform, cover type, and other physi-
cal conditions. Historical data, such as
maps and photographs, should be re-
viewed and long-time residents inter-
viewed to determine changes to the
stream corridor and associated ecosys-
tems. Major human-induced or natural
disturbances, such as land clearing,
floods, fires, and channelization,
should also be considered. These data
will be critical in understanding pre-
sent conditions, identifying a reference
condition, and determining future
trends.
Collecting Social, Cultural, and
Economic Data
In addition to physical, chemical, and
biological data, it is also important to
gather data on the social, cultural, and
economic conditions in the area. These
data more often than not will drive the
overall restoration effort, delimit its
scale, determine its citizen and land-
owner acceptance, determine ability to
coordinate and communicate, and gen-
erally decide overall stability and capa-
bility to maintain and manage. In
addition, these data are likely to be of
most interest to participants and should
be collected with their assistance to
avoid derailment or alteration of the
restoration effort due to misconceptions
and misinformation.
Properly designed surveys of social atti-
tudes, values, and perceptions can also
be valuable tools both to assess the
changes needed to accomplish the
restoration goals and to determine
changes in these intangible values over
time, throughout the planning process,
and after implementation.
Prioritizing Data Collection
Although data on both the historical
and baseline conditions related to
ecosystem structure and functions and
social, cultural, and economic values
are important, it is not always practical
to collect all of the available informa-
tion. Budgets and technical limitations
often place constraints on the amount
and types of data that can be collected.
It is therefore important for the techni-
cal team, advisory group, and decision
maker to prioritize the data needed.
At a minimum, the data necessary to ex-
plain the mechanisms or processes that
affect stream corridor conditions need
to be collected. To illustrate the chal-
lenges of data prioritization, consider
the example of identifying data for as-
sessing habitat functions. Potential
habitat data could include items such
as the extent of impacted fish, wildlife,
and other biota; ecological aspects; bio-
logical characteristics of soils and water;
vegetation (both native and nonnative);
and relationships among ecological
considerations (Figure 4.9). Depending
on the scope of the restoration plan,
however, data for all of these elements
might not be necessary to successfully
accomplish restoration. This holds es-
pecially true for smaller restoration ef-
forts in limited stream reaches.
4-18
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
An effective way to prioritize data col-
lection is through a scoping process
designed to determine those data which
are critical to decision making. The
scoping process identifies significant
concerns by institutional recognition
(laws, policies, rules, and regulations),
public recognition (public concern
and local perceptions), or technical
recognition (standards, criteria, and
procedures).
Data Analysis
Data analysis, like data collection, plays
an important role in all elements of
problem identification as well as other
aspects of the restoration process. Data
analysis techniques range from qualita-
tive evaluations using professional judg-
ment to elaborate computer models.
The scope and complexity of the
restoration effort, along with the bud-
get, will influence the type of analytical
techniques selected. A wealth of tech-
niques are discussed in the literature
and various manuals and will not be
listed in this document. Part I, however,
provides examples of the types of
processes and functions that need to be
analyzed. In addition, Part III discusses
some analytical techniques used for
condition analysis and restoration de-
sign, offers some analytic methodolo-
gies, and provides additional references.
Existing Stream Corridor
Structure, Functions, and
Disturbances
The second step in problem identifica-
tion and analysis is determining which
stream corridor conditions best charac-
terize the existing situation. Corridor
structure, functions, and associated dis-
turbances used to describe the existing
condition of the stream corridor will be
determined on a case-by-case basis. Just
as human health is indexed by such pa-
rameters as blood pressure and body
Figure 4.9: Characterizing stream corridor condi-
tions. Data collection and analysis are impor-
tant components of problem identification.
temperature, the condition of a stream
corridor must be indexed by an appro-
priate suite of measurable attributes.
There are no hard-and-fast rules about
which attributes are most useful in
characterizing the condition of stream
corridor structure and functions. How-
ever, as a starting point, consideration
should be given to describing present
conditions associated with the follow-
ing eight components of the corridor:
Hydrology
Erosion and sediment yield
Floodplain/riparian vegetation
Channel processes
Connectivity
Water quality
Aquatic and riparian species and
critical habitats
Corridor dimension
Since the ultimate goal is to establish
restoration objectives in terms of the
structure and functions of the stream
Problem and Opportunity Identification
-------
corridor, it is useful to characterize those
attributes which either measure or index
the eventual attainment of the desired
ecological condition. Some measurable
attributes that might be useful for de-
scribing the above components of a
stream corridor are listed in the box Mea-
surable Attributes for Describing Conditions
in the Stream Corridor. Detailed guidance
for quantifying many of the following at-
tributes is either described or referenced
elsewhere in this document.
Existing vs. Desired Structure
and Functions: The Reference
Condition
The third step in problem identification
and analysis is to define the conditions
within which the stream corridor prob-
lems and opportunities will be defined
and restoration objectives established.
It is helpful to describe how the present
baseline conditions of the stream corri-
dor compare to a reference condition that
represents, as closely as possible, the
desired outcome of restoration (Figure
4.10). The reference condition might
Figure 4.10: Example reference condition in
the western United States. A reference condi-
tion may be similar to what the corridor would
have been like in a state of relative "dynamic
equilibrium."
be similar to what the stream corridor
would have been like had it remained
relatively stable. It might represent a
condition less ideal than the pristine,
but substantially improved from the
present condition. Developing a set
of reference conditions might not be
an easy task, but it is essential to con-
ducting a good problem/opportunity
analysis.
Several information sources can be very
helpful in defining the reference condi-
tion. Published literature might provide
information for developing reference
conditions. Hydrologic data can often
be used to describe natural flow and
sediment regimes, and regional hy-
draulic geometry relations may define
reference conditions for channel dimen-
sions, pattern, and profile. Published
soil surveys contain soil map-unit de-
scriptions and interpretations reflecting
long-term ecological conditions that
may be suitable for reference. Species
lists of plants and animals (both histori-
cal and present) and literature on
species habitat needs provide informa-
tion on distribution of organisms, both
by habitat characteristics and by geo-
graphic range.
In most cases, however, reference condi-
tions are developed by comparison with
reference reaches or sites believed to be
indicative of the natural potential of the
stream corridor. The reference site might
be the predisturbance condition of the
stream to be restored, where such condi-
tions are established by examining relic
areas (enclosures, preserves), historical
photos, survey notes, and/or other de-
scriptive accounts. Similarly, reference
conditions may be developed from
nearby stream corridors in similar phys-
iographic settings if those streams are
minimally impacted by natural and
human-caused disturbances.
4-20
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
Attributes for Describ
Stream Corridor
nditions in the
Hydrology
- total (annual) discharge
- seasonal (monthly) discharge
- peak flows
minimum flows
- annual flow durations
rainfall records
- size and shape of the watershed
Erosion and Sediment Yield
watershed cover and soil health
- dominant erosion processes
- rates of surface erosion and mass
wasting
- sediment delivery ratios
- channel erosion processes and rates
- sediment transport functions
Floodplain/Riparian Vegetation
- community type
- type distribution
surface cover
- canopy
- community dynamics and succession
- recruitment/reproduction
- connectivity
Channel Processes
- flow characteristics
- channel dimensions, shape, profile,
and pattern
- substrate composition
- floodplain connectivity
- evidence of entrenchment and/or
deposition
lateral (bank) erosion
- floodplain scour
- channel avulsions/realignments
- meander and braiding processes
- depositional features
- scour-fill processes
- sediment transport class (suspended,
bedload)
Water Quality
color
- temperature, dissolved oxygen (BOD,
COD, and TOC)
- suspended sediment
- present chemical condition
- present macroinvertebrate condition
Aquatic and Riparian Species and
Critical Habitats
- aquatic species of concern and
associated habitats
- riparian species of concern and
associated habitats
- native vs. introduced species
- threatened or endangered species
- benthic, macroinvertebrate, or
vertebrate indicator species
Corridor Dimension
- plan view maps
- topographic maps
- width
- linearity, etc.
Problem and Opportunity Identification
4-21
-------
FAST
FORWARD
Preview
Chapter 7's
RFC section.
The Condition Continuum
One helpful way to conceptualize the
relationship between the current and ref-
erence conditions is to think of stream
corridor conditions as occurring on a
"condition continuum." At one end of this
continuum, conditions may be catego-
rized as being natural, pristine, or unim-
paired by human activities. A headwater
wilderness stream could exist near this
end of the continuum (Figure 4.11) At
the other end of the continuum, stream
corridor conditions may be considered
severely altered or impaired. Streams at
this end of the continuum could be totally
"trashed" streams or completely channel-
ized water conduits.
In concept, present conditions in the
stream corridor exist somewhere along this
condition continuum. The condition objec-
tive for stream restoration from an ecolog-
ical perspective should be as close to the
dynamic equilibrium as possible. It should
be noted, however, that once other impor-
tant considerations, such as political, eco-
nomic, and social values, are introduced
during the establishment of restoration
goals and objectives, the target may shift
to restoring the stream to some condition
that lies between the present situation and
dynamic equilibrium.
The proper functioning condition (PFC)
concept is used as a minimum target in
western riparian areas and can be the
basis on which to plan additional enhance-
ments (Pritchard et al. 1993, rev. 1995).
Figure 4.11: Condition continuum. The condition contin-
uum runs from (a) untouched by humans to (b) severely
impaired.
Source: L Goldman.
(b)
4-22
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
Causes of Altered or Impaired
Conditions
Conditions that provide the impetus
for stream corridor restoration activities
include degraded stream channel condi-
tions and degraded habitat. A thorough
analysis of the cause or causes of these
alterations or impairments is funda-
mental to identifying management op-
portunities and constraints and to
defining realistic and attainable restora-
tion objectives.
As discussed in Chapter 3, for every
stream corridor structural attribute and
function that is altered or impaired,
there may be a causal chain of events
responsible for the impairment. As a re-
sult, when conducting a problem analy-
sis, it is useful to consider factors that
affect stream corridor ecological condi-
tion at different levels or scales:
Landscape
Stream corridor and reach
Landscape Factors Affecting
Stream Corridor Condition
When analyzing landscape-scale factors
that contribute to existing stream corri-
dor conditions, disturbances that result
in changes in water and sediment deliv-
ery to the stream and in sources of con-
tamination should be considered. In
alluvial stream corridors, for example,
anything that changes the historical
balance between delivery of sediment
to the channel and sediment-transport
capacity of the stream will elicit a
change in channel conditions. When
sediment deliveries increase relative
to sediment-transport capacities, stream
aggradation usually occurs; when
sediment-transport capacities increase
relative to sediment delivery, stream in-
cision usually occurs. How the channel
responds to changes in flow and sedi-
ment regime depends on the magnitude
Common Impaired or Degraded Stream
Corridor Conditions
The following list provides some examples of impaired
stream corridor conditions. A more complete list of these
effects is provided in Chapter 3.
Stream aggradationfilling (rise in bed elevation over
time)
Stream degradationincision (drop in bed elevation
over time)
Streambank erosion
Impaired aquatic habitat
Impaired riparian habitat
Impaired terrestrial habitat
Loss of gene pool of native species
Increased peak flood elevation
Increased bank failure
Lower water table levels
Increase of fine sediment in the corridor
Decrease of species diversity
Impaired water quality
Altered hydrology
of change in runoff and sediment and
the type of sediment load being trans-
ported by the streamsuspended sedi-
ment or bedload.
The analysis of watershed effects on
channels is aided by the use of stan-
dard hydrologic, hydraulic, and sedi-
ment transport tools. Depending on
the available data, results may range
from highly precise to quantitative.
Altered flow regimes, for example,
might be readily discernible if the
stream has a long-term gauge record.
Otherwise, numerical runoff modeling
techniques might be needed to place
an approximate magnitude on the
Problem and Opportunity Identification
4-23
-------
Accelerated Bank Erosion:
The Importance of Understanding a Causal Chain of Events
To illustrate the concept of a causal chain
of events, consider the problem of accel-
erated bank erosion (Figure 4.12). Often
the cause of accelerated bank erosion
might be attributed to increases in peak
runoff or sediment delivery to a stream
when a surrounding watershed is under-
going land use changes; to the loss of
change in peak flows resulting from a
change in land use conditions. Water
developments such as storage reservoirs
and diversions also must be factored
into an analysis of altered watershed
hydrology (Figure 4.13).
The effects of altered land use on sedi-
ment delivery to streams may be as-
sessed using various analytical and
empirical tools. These are discussed in
Chapters 7 and 8. However, these tools
should be used with some caution un-
less they have been verified and cali-
brated with actual instream sediment
bank vegetation, which also increases the
vulnerability of the bank to erosion; or to
structures in the stream (e.g., bridge abut-
ments) that redirect the water flow into
the bank. In this case, determining that
bank erosion has increased relative to
some reference rate is central to the iden-
tification of an impaired condition. In
addition, understanding the cause or
causes of the increased erosion is a key
step in effective problem analysis. It is crit-
ical to the solution of the problem that
this understanding be factored into the
development of restoration objectives and
management alternatives.
Figure 4.12: Bank erosion. The cause(s) of bank
erosion should be identified.
sampling data or measured reservoir
sedimentation rates.
The stream channel itself might provide
some clues as to whether it is experienc-
ing an increase or decrease in sediment
delivery from the watershed relative to
sediment-transport capacity. Special at-
tention should be paid to channel ca-
pacities and depositional features such
as sand or gravel bars. If flooding seems
to be more frequent, it might be an in-
dication that aggradation is occurring.
Conversely, if there is evidence of chan-
nel entrenchment, such as exposed
bridge pier or abutment footings, degra-
dation is occurring. Similarly, if the
4-24
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
number and size of gravel bars are sig-
nificantly different from what is evident
in historical photos, for example, the
difference might be an indication that
either aggradation or erosion has been
enhanced. Care is needed when using
the channel to interpret possible
changes in watershed conditions since
similar channel symptoms can also be
caused by changes in conditions within
the stream corridor itself or by natural
variation of the hydrograph.
Stream Corridor and Reach
Factors Affecting Stream
Corridor Conditions
In addition to watershed factors affect-
ing stream corridor conditions, it is im-
portant to consider disturbances at the
stream corridor and reach scales. In
general, stream corridor structural at-
tributes and functions are greatly af-
fected by several important categories of
activities if they occur within the corri-
dor. Chapter 3 explores these in more
detail; the following are some of the ac-
tivities that commonly impact corridor
structure and function.
Activities that alter or remove stream-
bank and riparian vegetation (e.g.,
grazing, agriculture, logging, and
urbanization), resulting in changes in
the stability of streambanks, runoff
and transport of contaminants, water
quality, or habitat characteristics of
riparian zones (Figure 4.14).
Activities that physically alter the mor-
phology of channels, banks, and
riparian zones, resulting in effects
such as the displacement of aquatic
and riparian habitat and the disrup-
tion of the flow of energy and materi-
als (e.g., channelization, levee con-
struction, gravel mining, and access
trails).
Instream modifications that alter
channel shape and dimensions, flow
Figure 4.13: Water releases below a dam.
Altering the flow regime of Glen Canyon Dam
altered the stream condition.
hydraulics, sediment-transport char-
acteristics, aquatic habitat, and water
quality (e.g., dams and grade stabi-
lization measures, bank riprap, logs,
bridge piers, and habitat "enhance-
ment" measures) (Figure 4.15). In
the case of logs, it might be the loss
of such structures rather than their
addition that alters flow hydraulics
and channel structure.
Altered riparian vegetation and physical
modification of channels and flood-
plains are primary causes of impaired
stream corridor structure and functions
because their effects are both profound
and direct. Addressing the causes of
these changes might offer the best, most
feasible opportunities for restoring
stream corridors. However, the altered
vegetation and physical modifications
also may create some of the most sig-
nificant challenges for stream corridor
restoration by constraining the number
or type of possible solutions.
It is important to remember that there
are no simple analytical methods
available for analyzing relationships
'review Chap-
ters 7 and 8,
Analytical and
Empirical Tools
section.
Problem and Opportunity Identification
4-25
-------
Preview
Chapter 7's
Quantitative
Tools section.
Figure 4.14: Residential development.
Urbanization can severely impair conditions
critical for riparian vegetation by increasing
impervious surfaces.
between activities or events potentially
disturbing the stream corridor and the
structure and functions defining the
corridor. However, there are modes by
which stream corridor activities and
structures can affect ecological condi-
tions that involve both direct and indi-
rect impacts. The box Examples of How
Activities Occurring Within the Corridor
Can Affect Structure and Functions pro-
vides some examples of the modes by
which activities can affect stream corri-
dor structure and functions.
In conducting the problem analysis, it
is important to investigate the various
modes of ecological interaction at the
reach and system scales. The analysis
might need to be subjective and deduc-
tive, in which case use of an interdisci-
plinary team is essential. In other cases,
the analysis might be enhanced by ap-
plication of available hydrologic, hy-
draulic, sedimentation, water quality, or
habitat models.
Whatever the situation, it is likely that
the analysis will require site-specific ap-
plication of ecological principles aided
by a few quantitative tools. It will
rarely be possible to determine
causative factors for resource impair-
ment using uninterpreted results from
off-the-shelf analytical models. Part III,
Chapter 7, contains a detailed discus-
sion of some of the quantitative tools
available to assist in the analysis of the
resource conditions within the stream
corridor ecosystem.
Determination of
Management Influence on
Stream Corridor Conditions
Once the conditions have been identi-
fied and the causes of those conditions
described, the key remaining question is
whether the causative factors are a func-
tion of and responsive to management.
Specific management factors that con-
tribute to impairment might or might
not have been identified with the causes
of impairment previously identified.
Figure 4.15: Riparian vegetation and structure.
The loss of logs in a stream alters flow
hydraulics and channel structure.
4-26
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
To illustrate, consider again the example
of increased bank erosion. An initial
analysis of impaired conditions might
identify causes such as land uses in the
watershed that are yielding higher flows
and sediment loads, loss of streambank
vegetation, or redirection of flow from
instream modifications. None of these,
however, identify the role of manage-
ment influences. For example, if higher
water and sediment yields are a func-
tion of improper grazing management,
the problem might be mitigated simply
by altering grazing practices.
The ability to identify management in-
fluences becomes critical when identify-
ing alternatives for restoration.
Description of past management influ-
ences may prevent the repetition of pre-
vious mistakes and should facilitate
prediction of future system response for
evaluating alternatives. Recognition of
management influences also is impor-
tant for predicting the effectiveness of
mitigation and the feasibility of specific
treatments. Identifying the role of man-
agement is a key consideration when
evaluating the ability of the stream cor-
ridor to heal itself (e.g., without man-
agement, with management, with
management plus additional treat-
ments). The identification of past man-
agement, both in the watershed and in
the stream corridor, and its influence
on those factors causing impairment
will therefore help to sharpen the focus
of the restoration effort.
Problem or Opportunity
Statements for Stream
Corridor Restoration
The final step in the process of prob-
lem/opportunity identification and
analysis is development of concise
statements to drive the restoration ef-
fort. Problem/opportunity statements
not only serve as a general focus for
Localized Impacts Affecting the Stream
Corridor
Spatial considerations in stream corridor restoration are
usually discussed at the landscape, corridor, and stream
scales (e.g., connections to other systems, minimum
widths, or maximum edge concerns). However, the criti-
cal failures in corridor systems can often occur at the
reach scale, where a single break in continuity or other
weakness can have a domino effect on the entire corri-
dor. Just as uncontrolled watershed degradation can
doom stream corridor restoration effectiveness, so can
specific sites where critical problems exist that can pre-
vent the whole corridor from functioning effectively.
Examples of weaknesses or problems at the reach scale
that might affect the whole corridor are wide-ranging.
Barriers to fish passage, lack of appropriate shade and
resultant loss of water temperature moderation, breaks
in terrestrial migration lands, or narrow points that make
some animals particularly vulnerable to predators can
often alter conditions elsewhere in the corridor. In addi-
tion, other sites might be direct or indirect source areas
for problems, such as headcuts or rapidly eroding banks
that contribute excessive sediment to the stream and
instability to the system, or locations with populations of
noxious exotic plant species that can spread to other
parts of the corridor system. Some site-specific land use
problems can also have critical impacts on corridor
integrity, including chronic damage from grazing live-
stock, irrigation water returns, and uncontrolled storm
water outflows.
the restoration effort but also become
the basis for developing specific restora-
tion objectives. Moreover, they form
the basis for determining success or
failure of the restoration initiative.
Problem/opportunity statements are
therefore critical for design of a relevant
monitoring approach.
Problem and Opportunity Identification
4-27
-------
Examples of How Activities Occurring
Within the Corridor Can Affect
Structure and Functions
Direct disturbance or displacement of aquatic and/or
riparian species or habitats
Indirect disturbance associated with altered stream
hydraulics and sediment-transport capacity
Indirect disturbance associated with altered channel
and riparian zone sedimentation dynamics
Indirect disturbance associated with altered surface
water-ground water exchanges
Indirect disturbance associated with chemical
discharges and altered water quality
For maximum effectiveness, these
statements should usually have the fol-
lowing two characteristics:
They describe impaired stream corri-
dor conditions that are explicitly stat-
ed in measurable units and can be
related to specific processes within
the stream corridor.
They describe deviation from the
desired reference condition (dynam-
ic equilibrium) or proper function-
ing condition for each impaired
condition.
4-28
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
CASESUJDY Bluewater Creek
The watershed analysis and subsequent treat-
ments performed at Bluewater Creek, New
Mexico, demonstrate successful watershed and
stream corridor restoration. Although most of the
work has taken place on federal land, the intermix-
ing of private lands and the values and needs of
the varied publics concerned with the watershed
make it a valuable case study. The project, begun
in 1984, has a record of progress and improved
land management. The watershed received the
1997 Chief's Stewardship Award from the Chief of
the Forest Service and continues to host numerous
studies and research projects.
Located in the Zuni mountains of north-central
New Mexico, Bluewater Creek drains a 52,042-acre
watershed that enters Bluewater Lake, a 2,350-acre
reservoir in the East Rio San Jose watershed.
Bluewater Creek and Lake provide the only oppor-
tunity to fish for trout and other coldwater species
and offer a unique opportunity for water-based
recreation in an otherwise arid part of New Mexico.
The watershed has a lengthy history of complex
land uses. Between 1890 and 1940, extensive log-
ging using narrow-gauge railroad technology cut
over much of the watershed. Extensive grazing of
livestock, uncontrolled fires, and some mining
activity also occurred. Following logging by private
enterprises, large portions of the watershed were
sold to the USDA Forest Service in the early 1940s.
Grazing, some logging, extensive roading, and
increased recreational use continued in the water-
shed. The Mt. Taylor Ranger District of the Cibola
National Forest now manages 86 percent of the
watershed, with significant private holdings (12.5
percent) and limited parcels owned by the state of
New Mexico and Native Americans.
In the early 1980s, local citizens worked with the
Soil Conservation Service (now Natural Resources
Conservation Service) to begin a Resource
Conservation and Development (RC&D) project to
protect water quality in the stream and lake as
well as limit lake sedimentation harming irrigation
and recreation opportunities. Although the RC&D
project did not develop, the Forest Service, as the
major land manager in the watershed, conducted
a thorough analysis on the lands it managed and
implemented a restoration initiative and monitor-
ing that continue to this day.
The effort has been based on five goals: (1) reduce
flood peaks and prolong baseflows, (2) reduce soil
loss and resultant downstream channel and lake
sedimentation, (3) increase fish and wildlife pro-
ductivity, (4) improve timber and range productivi-
ty, and (5) demonstrate proper watershed analysis
and treatment methods. Also important is close
adherence to a variety of legal requirements to
preserve the environmental and cultural values of
the watershed, particularly addressing the needs of
threatened, endangered, and sensitive plant and
animal species; preserving the rich cultural history
of the area; and complying with requirements of
the Clean Water Act.
For analysis purposes, the watershed was divided
into 13 subwatersheds and further stratified based
on vegetation, geology, and slope. Analysis of data
gathered measuring ground cover transects and
channel analysis from August 1984 through July
1985 resulted in eight major conclusions: (1) areas
forested with mixed conifer and ponderosa pine
species were generally able to handle rainfall and
snowmelt runoff; (2) excessive peak flows, as well
as normal flows continually undercut steep chan-
nel banks, causing large volumes of bank material
to enter the stream and lake system; (3) most
perennial and intermittent channels were lacking
the riparian vegetation they needed to maintain
streambank integrity; (4) most watersheds had an
excessive number of roads (Figure 4.16); (5) trails
caused by livestock, particularly cattle, concentrate
runoff into small streams and erodible areas; (6)
several key watersheds suffered from livestock
overuse and improper grazing management sys-
tems; (7) some instances of timber management
practices were exacerbating watershed problems;
Problem and Opportunity Identification
4-29
-------
Figure 4.16: Vehicle traffic through wet meadow in
Bluewater Creek, NM. (May 1984.) Such traffic compacts
and damages soil, changes flow patterns, and induces
gully erosion.
and (8) excessive runoff in some subwatersheds
continued to degrade the main channel.
Based on the conclusions of the analysis, a broad
range of treatments were prescribed and imple-
mented. Some were active (e.g., construction of
particular works or projects); others were more
passive (e.g., adjustments to grazing strategies).
Channel treatments such as small dams, gully
headcut control structures, grade control struc-
tures, porous fence revetments (Figures 4.17,
4.18, and 4.19), and channel crossings (Figure
4.20) were used to affect flow regimes, channel
stability, and water quality. Riparian plantings,
riparian pastures, and beaver management pro-
grams were also established, and meander
reestablishment and channel relocation were con-
ducted. Land treatments, such as the establish-
ment of best management practices (BMPs) for
livestock, timber, roads, and fish and wildlife, were
developed to prevent soil loss and maintain site
productivity.
In a few cases, land and channel treatments were
implemented simultaneously (e.g., livestock drift
Figure 4.17: Recently installed treatment. (April 1987.)
Porous fence revetment designed to reduce bank failure.
Figure 4.18: Porous fence revetment aided by bank
sloping. (August 1987.) The photo shows initial revege-
tation during first growing season following treatment
installation.
fences and seasonal area closures). Additional
attention was paid to improved road management
practices, and unnecessary roads were closed.
Results of the project have largely met its goals,
and the watershed is more productive and enjoy-
able for a broad range of goods, services, and val-
ues. Although one weakness of the project was
the lack of a carefully designed monitoring and
4-30
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
Figure 4.19: Porous fence revetments after two growing
seasons. (September 1988.) Vegetation is noticeably
established over first growing season.
Figure 4.20: Multiple elevated culvert array at crossing
of wet meadow. (June 1997.) The culvert spreads flow
and decreases erosion energy, captures sediment
upstream, reduces flood peaks, and prolongs baseflows.
evaluation plan, observers generally agree that the
completed treatments continue to perform their
designed function, while additional treatments add
to the success of the project.
Most of the small in-channel structures are func-
tioning as designed. The meander reestablishment
has lengthened the channel and decreased gradi-
ent in a critical reach. The channel relocation pro-
ject has just completed its first year, and initial
results are promising. Beaver have established
themselves along the main channel of Bluewater
Creek, providing significant habitat for fish and
wildlife, as their ponds capture sediment and mod-
erate flood peaks. The watershed now provides a
more varied and robust population of fish and
wildlife species. Changes in road management
have yielded significant results. Road closures have
removed traffic from sensitive areas, and recon-
struction of two key roads has reduced sediment
damages to the stream. Special attention to road
crossings of wet meadows has begun to rehabili-
tate scores of acres dewatered by improper cross-
ings. Range management techniques (e.g., com-
bined allotments, improved fencing, and more
modern grazing strategies) are improving water-
shed condition. A limited timber management pro-
gram on the federal property has had beneficial
impacts on the watershed, but significant timber
harvest on private lands provided a cause for con-
cern, particularly regarding compliance with Clean
Water Act best management practices.
The local citizens who use the watershed have
benefited from the improved conditions.
Recreation use continues to climb.
Problem and Opportunity Identification
4-31
-------
Problem/Opportunity Statements
Problem/Opportunity statements should follow
directly from the analysis of existing and reference
stream corridor conditions. These statements can
be viewed as an articulation of some of the poten-
tial benefits that can be realized through restora-
tion of the structure and functions of the stream
corridor. For example, problem statements might
focus on the impaired structural attributes and
functions needing attention, while associated
opportunities might focus on reintroduction of
native species that were previously eliminated from
the system. Problem/Opportunity statements can
also focus on the economic benefits of a proposed
restoration initiative. By identifying such economic
benefits to local landowners, it may be possible to
increase the number of private citizens participat-
ing in the planning process.
Example problem statement:
Coarse sediment
from past
mass wasting
in unit 3
Geomorphic Input
Time Frame
Watershed Process
Hillslope Unit Locator
associated with clearcut logging
on unstable slopes is
reducing pools
on segments 1 and 2
Activity
Conditions and Modifiers
Channel Effects
Locator
and degrading summer rearing habitat.
Resource Effects
Example opportunity statements:
To prevent streambank erosion and sediment
damage and provide quality streamside vegeta-
tion through bioengineering techniquesFour
Mile Run, Virginia.
To protect approximately 750 linear feet of Sligo
Creek through the construction of a parallel pipe
system for storm water discharge controlSligo
Creek, Maryland.
To enhance the creek through reconstruction of
instream habitat (e.g., pools and riffles)Pipers
Creek, Washington.
To reintroduce nongame fish and salamanders in
conjunction with implementing several stream
restoration techniques and eliminating point
source dischargesBerkeley Campus Creek,
California.
Example statements adapted from Center for
Watershed Protection 1995.
4-32
Chapter 4: Getting Organized and Identifying Problems and Opportunities
-------
Developing * |
Goals, Objectives,
and Restoration
Alternatives M
-------
5.A Developing Restoration Goals and Objectives
How are restoration goals and objectives defined?
How do you describe desired future conditions for the stream corridor and surrounding
natural systems?
What is the appropriate spatial scale for the stream corridor restoration?
What institutional or legal issues are likely to be encountered during a restoration?
What are the means to alter or remove the anthropogenic changes that caused the need for
the restoration (i.e., passive restoration)?
5.B Alternative Selection and Design
How does a restoration effort target solutions to treat causes of impairment and not
just symptoms?
What are important factors to consider when selecting among various restoration
alternatives?
What role does spatial scale, economics, and risk play in helping to select the best
restoration alternative?
Who makes the decisions?
When is active restoration needed?
When are passive restoration methods appropriate?Chapter 6: Implement, Monitor, Evaluate,
and Adapt
-------
Developing
Goals,
Objectives, and
Restoration
Alternatives
5.A Developing Restoration Goals and
Objectives
5.B Alternative Selection and Design
Once the basic organizational steps
have been completed and the prob-
lems/opportunities associated with the
stream corridor have been identified, the
next two stages of the restoration plan
development process can be initiated.
These two stages, the development of
restoration goals and objectives and alter-
native selection and design, require input
from all partners. The advisory group
should work in collaboration with the de-
cision maker(s) and technical teams.
During the objective development, alter-
native selection, and design stages, it is
important that continuity be maintained
among the fundamental steps of the
restoration process. In other words, plan-
ners must work to ensure a logical flow
and relationship between problem and
opportunity statements, restoration goals
and objectives, and design.
Remember that the restoration planning
process can be as complex as the stream
corridor to be restored. A project might
involve a large number of landowners and
decision makers. It might also be fairly
simple, allowing planning through a
streamlined process. In either case, proper
planning will lead to success.
Proper planning in the beginning of the
restoration process will save time and
money for the life of the project. This is
-------
often accomplished by managing
the causes rather than the
symptoms.
This chapter is divided into two sec-
tions that describe the basic steps
of defining goals and objectives, se-
lecting alternatives, and designing
restoration measures.
Section 5.A: Developing
Restoration Goals and Objectives
Restoration objectives are essential
for guiding the development and
implementation of restoration ef-
forts and for establishing a means
to measure progress and evaluate
success. This section outlines some
of the major considerations that
need to be taken into account in
developing restoration goals and
objectives for a restoration plan.
Although active restorations that
include the installation of designed
measures are common, the "no
action" or passive alternative might
be more ecologically desirable,
depending on the specific goals
and time frame of the plan.
Section 5.8: Alternative Selection
and Design
The selection of restoration alterna-
tives is a complex process that is
intended to address the identified
problems/opportunities and accom-
plish restoration goals and objec-
tives. Some of the important
factors to consider in designing
restoration measures, as well as
some of the supporting analysis
that facilitates alternative selection,
are discussed.
5-2
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
5.A Developing Restoration Goals and
Objectives
Developing goals and objectives for
a stream corridor restoration effort
follows problem/opportunity identifica-
tion and analysis. The goals develop-
ment process should mark the
integration of the results of the assess-
ment of existing and desired stream
corridor structure and functions with
important political, economic, social,
and cultural values. This section
presents and explains some of the fun-
damental components of the goal and
objective development process.
Defining Desired Future
Stream Corridor Conditions
The development of goals and objec-
tives should begin with a rough outline,
as discussed in Chapter 4, and with the
definition of the desired future condition
of the stream corridor and surrounding
landscape (Figure 5.1). The desired fu-
ture condition should represent the
common vision of all participants. This
clear, conceptual picture is necessary to
serve both as a foundation for more
specific goals and objectives and as a
target toward which implementation
strategies can be directed.
The vision statement should be consis-
tent with the overall ecological goal of
restoring stream corridor structure and
functions and bringing the system as
close to a state of dynamic equilibrium
or proper functioning condition as
possible.
The development of this vision state-
ment should be seen as an opportunity
for participants to articulate an ambi-
tious ecological vision. This vision will
ultimately be integrated with important
social, political, economic, and cultural
values.
Components of the Goal and Objective
Development Process
Define the desired future condition.
Identify scale considerations.
Identify restoration constraints and issues.
Define goals and objectives.
Identifying Scale
Considerations
In developing stream corridor restora-
tion goals and objectives it is important
to consider and address the issue of
scale. The scale of stream corridor
restoration efforts can vary greatly, from
working on a short reach to managing a
large river basin corridor. As discussed
Figure 5.1: Example of future conditions. The
desired future condition should represent the
common vision of all participants.
Developing Restoration Goals and Objectives
5-3
-------
CASESUJDY Chesapeake Bay Program
A unique partnership that spanned across a/I
scales of the Chesapeake Bay watershed was
formed in 1983. The Chesapeake Bay Agreement
was signed that year by the District of Columbia,
the state of Maryland, the Commonwealths of
Pennsylvania and Virginia, the Chesapeake Bay
Commission (a tri-state legislative body), and
the federal government represented by the
Environmental Protection Agency to coordinate
and direct the restoration of the Chesapeake Bay.
Recognizing that local cooperation would be
vital in implementing any efforts, the Executive
Committee created the Local Government Advisory
Committee (LGAC) in 1987. The LGAC acts as a
conduit to communicate current efforts in the
Program to the local level, as well as a platform for
local governments to voice their perceptions, ideas,
and concerns. The Land Growth and Stewardship
Subcommittee was formed in 1994 to encourage
actions that reduce the impacts of growth on the
Bay and address other issues related to population
growth and expansion in the region.
The Chesapeake Bay was the first estuary targeted
for restoration in the 1970s. Based on the scientific
data collected during that time, the agreement tar-
geted 40 percent reductions in nutrients, nitrogen,
and phosphorus by the year 2000. The committee
has been instrumental in moving up the tributaries
of the bay and improving agricultural practices,
removing nutrients, and educating the millions of
residents about their role in improving the quality
of the bay. Success has been marked by reduction
in nutrients and an increase in populations of
striped bass and other species (Figure 5.2). Recent
fish kills in the watershed rivers, however, are
reminders that maintaining the health of the
Chesapeake Bay is a continuing challenge.
Success at the local level is key to the success of
the overall program. Chesapeake Bay
Communities' Making the Connection catalogs
some of the local initiatives to restore local envi-
ronments and improve the condition of the bay. In
Lancaster County, Pennsylvania, for example, a
Stream Team was formed to preserve and restore
the local streams. Its primary role is to coordinate
restoration efforts involving local landowners, vol-
unteers, and available programs. In one case, the
Stream Team was able to arrange materials for a
local fishing group and a farmer to fence a pasture
stream and plant trees. With continuous efforts
such as this, the Chesapeake Bay will become
cleaner one tributary at a time.
Figure 5.2: Chesapeake Bay. The Chesapeake Bay is a
unique estuarine ecosystem protected through intera-
gency cooperation.
Source: C. Zabawa.
5-4
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
previously, it is important to recognize,
however, that the functions of a specific
streambank or reach ecosystem are not
performed in isolation and are linked
to associated ecosystems in the sur-
rounding landscape. As a result, goals
and objectives should recognize the
stream corridor and its surrounding
landscape.
The Landscape Scale
Technical considerations in stream cor-
ridor restoration usually encompass the
landscape scale as well as the stream
corridor scale. These considerations
may include political, economic,
historical, and/or cultural values; nat-
ural resource management concerns;
and biodiversity (Landin 1995). The
following are some important issues
relevant to the landscape scale.
Regional Economic and Natural
Resource Management Considerations
Regional economic priorities and nat-
ural resource objectives should be iden-
tified and evaluated with respect to
their likely influence on the restoration
effort. It is important that restoration
goals and objectives reflect a clear un-
derstanding of the concerns of the peo-
ple living in the region and the
immediate area, as well as the priorities
of resource agencies responsible for
managing lands within the restoration
target area and providing support for
the initiative (Figure 5.3).
In many highly developed areas,
restoration may be driven largely by a
general recognition that stream corri-
dors provide the most satisfactory op-
portunities to repair and preserve
natural environments in the midst of
increasingly dense human occupation.
In wildland areas, stream corridor
restoration might be pursued as part
of an overall ecosystem management
program or to address the requirements
of a particular endangered species.
Land Use Considerations
As discussed in Chapter 2, many of the
characteristics and functions of the
stream corridor are controlled by hydro-
logic and geomorphic conditions in the
watershed, particularly as they influence
streamflow regime, sediment move-
ment, and inputs of nutrients and pol-
lutants (Brinson et al. 1995).
As introduced in Chapter 3, changes in
land use and increases in development
are a concern, particularly because they
can cause rapid changes in the delivery
of storm water to the stream system,
thereby changing the basic hydrologic
patterns that determine stream configu-
ration and plant community distribu-
tion (Figure 5.4). In addition, future
development can influence what the
stream corridor will be expected to ac-
complish in terms of processing or stor-
ing floodwaters or nutrients, or with
respect to providing wildlife habitat or
recreation opportunities.
Review Chap-
ters 2 and 3.
Figure 5.3: Western streamlandscape scale.
Developing goals and objectives requires the
consideration of important social, economic,
ecological, and natural resource factors at the
landscape scale.
Developing Restoration Goals and Objectives
5-5
-------
Figure 5.4: Urban stream corridor. Population
growth and land use trends, such as urbaniza-
tion, should be considered when developing
restoration goals and objectives.
Landscape concerns pertinent to devel-
oping goals and objectives for stream
corridor restoration should also include
an assessment of land use and projected
development trends in the watershed.
By making an effort to accommodate
predictable future land use and devel-
opment patterns, degradation of stream
corridor conditions can be prevented or
reduced.
Biodiversity Considerations
The continuity that corridors provide
among different areas and ecosystem
types has often been cited as a major
tool for maintaining regional biodiver-
sity because it facilitates animal move-
ment (particularly for large mammals)
and prevents isolation of plant and ani-
mal populations. However, there has
been some dispute over the effective-
ness of corridors to accomplish these
objectives and over the creation of inap-
propriate corridors having adverse con-
sequences (Knopf 1986, Noss 1987,
Simberloff and Cox 1987, Mann and
Plummer 1995).
Where corridor restoration is intended
to result in establishing connectivity on
a landscape scale, management objec-
tives and options should reflect natural
patterns of plant community distribu-
tion and should be built to provide as
much biodiversity as possible. In many
instances, however, the driving force be-
hind restoration is the protection of cer-
tain threatened, endangered, game, or
other specially targeted species. In these
cases a balance must be struck. A por-
tion of the overall restoration plan can
be directed toward the life requirements
of the targeted species, but on the
whole the goal should be a diverse
community (Figure 5.5).
The Stream Corridor Scale
Each stream corridor targeted for
restoration is unique. A project goal of
restoring multiple ecological functions
might encompass the channel systems,
the active floodplain, and possibly adja-
cent hill slopes or other buffer areas
that have the potential to directly and
indirectly influence the stream or pro-
tect it from surrounding land uses
(Sedell et al. 1990). A wide corridor is
Figure 5.5: Animal population dynamics.
Restoration plans may target species, but biodi-
versity should be the basic goal of restoration.
5-6
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
most likely to include a range of biotic
community types and to perform many
of the stream functions (floodwater and
sediment storage, nutrient processing,
fish and wildlife habitat, and others)
that the restoration effort is intended to
restore. In many cases, however, it will
not be possible to reestablish the origi-
nal corridor width, and restoration will
be focused on a narrower strip of land
directly adjacent to the channel.
Where narrow corridors are established
through urban or agricultural land-
scapes, certain functions might be re-
stored (e.g., stream shading), while
others might not (e.g., wildlife move-
ment). In particular, very narrow corri-
dors, such as western riparian areas,
may function largely as edge habitat
and will favor unique and sometimes
opportunistic plant and animal
species. In some situations, creating a
large amount of edge habitat might be
detrimental to species that require
large forested habitat or are highly vul-
nerable to predation or nest parasitism
and disturbances.
The corridor configuration and restora-
tion options depend to a large extent
on the pattern of land ownership and
use at the stream corridor scale. Corri-
dors that traverse agricultural land may
involve the interests of many individual
landowners with varying levels of com-
mitment to or interest in the restoration
initiative.
Often, landowners will not be inclined
to remove acreage from production or
alter land use practices without incen-
tive. In urban settings, citizen groups
may have a strong voice in the objec-
tives and layout of the corridor. On
large public land holdings, manage-
ment agencies might be able to commit
to the establishment and management
of stream corridors and their water-
sheds, but the incorporation of compet-
ing interests (timber, grazing, mining,
recreation) that are not always consis-
tent with the objectives of the restora-
tion plan can be difficult. In most cases,
the final configuration of the corridor
should balance multiple and often con-
flicting objectives, including optimizing
ecological structure and function and
accommodating the diverse needs of
landowners and other participants.
The Reach Scale
A reach is the fundamental unit for de-
sign and management of the stream
corridor. In establishing goals and ob-
jectives, each reach must be evaluated
with regard to its landscape and indi-
vidual characteristics, as well as their in-
fluence on stream corridor function and
integrity. For example, steep slopes adja-
cent to a channel reach must be consid-
ered where they contribute potentially
significant amounts of runoff, subsur-
face flow, sediment, woody debris, or
other inputs. Another reach might be
particularly active with respect to chan-
nel migration and might warrant ex-
panding the corridor relative to other
reaches to accommodate local stream
dynamics.
Identifying Restoration
Constraints and Issues
Once participants have reached consen-
sus on the desired future condition and
examined scale considerations, atten-
tion should be given to identifying
restoration constraints and issues. This
process is important in that it helps
identify limitations associated with es-
tablishing specific restoration goals and
objectives. Moreover, it provides the in-
formation that will be needed when in-
tegrating ecological, social, political,
and economic values.
Due to the innumerable potential chal-
lenges involved in identifying all of the
constraints and issues, it is often help-
FAST
FORWARD
Preview Chap-
ter 6's Adaptive
Management
section.
Developing Restoration Goals and Objectives
5-7
-------
fill to rely on the services of the inter-
disciplinary technical teams. Team
members support one another and pro-
vide critical expertise and the experience
necessary to investigate potential con-
straints. The following are some of the
restoration constraints and issues, both
technical and nontechnical, that should
be considered in defining restoration
goals and objectives.
Technical Constraints
Technical constraints include the avail-
ability of data and restoration technolo-
gies. In terms of data availability, it is
important that the technical team begin
by compiling and analyzing data avail-
able on stream corridor structure and
functions. Analyzing these data will en-
able the identification of information
gaps and should allow the restoration
effort to proceed, even though all of the
information might not be at hand. It
should be noted that there is usually a
wealth of technical information avail-
able either in published sources or in
public agency offices as unpublished
source material.
In addition to data availability, a sec-
ond technical constraint might involve
the tools or techniques used to analyze
or collect stream corridor data. Some
restoration techniques and methodolo-
gies are not complete and might not be
sufficient to conduct the restoration ef-
fort. It is also generally known that
technology transfer and dissemination
associated with available techniques are
far behind the existing information
base, and field personnel might not
readily have access to needed informa-
tion. It is important that the technical
teams are up-to-date with restoration
technology and are prepared to modify
implemented plans through adaptive
management as necessary.
Figure 5.6: Field sampling. Collecting the right
kinds of data with the proper quality control
and translating that data into information use-
ful for making decisions is a challenge.
Quality Assurance, Quality
Control
The success of a stream corridor restora-
tion plan depends on the following:
Efficient and accurate use of existing
data and information.
Reliable collection of new data that
are needed, recognizing the required
level of precision and accuracy
(Figure 5.6).
Interpretation of the meaning of the
data, including translating the data
into information that can be used to
make planning decisions.
A locally led, voluntary approach.
The concept of quality assurance or
quality control is not new. When time,
materials, or money are to be ex-
pended, results should be as reliable
and efficiently derived as possible. Pro-
visions for quality control or quality as-
surance can be built into the restoration
plan, especially if a large number of
5-8
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
contractors, volunteers, and other peo-
ple not directly under the control of the
planners are involved (Averett and
Schroder 1993).
Many standards, conventions, and pro-
tocols exist to ensure the quality or reli-
ability of information used for planning
a restoration (Knott et al. 1992), in-
cluding the following:
Sampling
Field analytical equipment
Laboratory testing equipment
Standard procedures
Training
Calibrations
Documentation
Reviews
Delegations of authority
Inspections
The quality of work and the restoration
actions can be ensured through the fol-
lowing (Shampine et al. 1992, Stanley
et al. 1992, Knott et al. 1993):
Training to ensure that all persons
fully understand what is expected of
them.
Products that are produced on time
and that meet the plan's goals and
objectives.
Established procedures for remedial
actions or adaptive management,
which means being able to make
adjustments as monitoring results are
analyzed.
Nontechnical Constraints
Nontechnical constraints consist of fi-
nancial, political, institutional, legal
and regulatory, social, and cultural con-
straints, as well as current and future
land and water use conflicts. Any one of
these has the potential to alter, post-
pone, or even stop a restoration initia-
tive. As a result, it is important that the
advisory group and decision maker con-
sider appointing a technical team to in-
vestigate these issues prior to defining
restoration goals and objectives.
Contained below is a brief discussion of
some of the nontechnical issues that
can play a role in restoration initiatives.
Although many general examples and
case studies offer experience on address-
ing nontechnical constraints, the nu-
ances of each issue can vary by
initiative.
Land and Water Use Conflicts
Land and water use conflicts are fre-
quently a problem, especially in the
western United States. The historical,
social, and cultural aspects of grazing,
mining, logging, water resources devel-
opment and use, and unrestricted use
of public land are emotional issues that
require coordination and education so
that local and regional citizens under-
stand what is being proposed in the
restoration initiative and what will be
accomplished.
Financial Issues
Planning, design, implementation, and
other aspects of the restoration initia-
tive must stay within a budget. Since
most restoration efforts involve public
agencies, the institutional, legal, and
regulatory protocols and bureaucracies
can delay restoration and increase costs.
It is extremely important to recognize
these problems early to keep the initia-
tive on schedule and preclude or at
least minimize cost overruns.
In some cases, funds might be insuffi-
cient to accomplish restoration. The
means to undertake the initiative can
often be obtained by seeking out and
working with a broad variety of cost-
and work-sharing partners; seeking out
and working with volunteers to perform
Developing Restoration Goals and Objectives
5-9
-------
Permits
Federal, state, or local permits might be required
for some types of stream restoration activities.
Some states, such as California, require permits for
any activity in a streambed. Placement of dredged
or fill material in waters of the United States
requires a Clean Water Act (CWA) Section 404 per-
mit from the US Army Corps of Engineers or, when
the program has been delegated, from the state.
The CWA requires the application of the Section
404(b)(1) guidelines issued by the Environmental
Protection Agency in determining whether dis-
charge should be allowed. A permit issued under
Section 10 of the Rivers and Harbors Act of 1899
might also be required for activities that change the
course, condition, location, or capacity of navigable
waters.
Activities that could trigger the need for a CWA
Section 404 permit include, but are not limited to,
re-creation of gravel beds, sand bars, and riffle and
pool habitats; wetland restoration; placement of
tree root masses; and placement of revetment on
channel banks. CWA Section 404 requires that a
state or tribe (one or both as appropriate) certify
that an activity requiring a Section 404 permit is
consistent with the state's or tribe's water quality
standards. Given the variety of actions covered by
the CWA, as well as jurisdiction issues, it is vital to
contact the Corps of Engineers Regulatory Branch
and appropriate state officials early in the planning
process to determine the conditions triggering the
need for permits as well as how to best integrate
permit compliance needs into the planning and
design of the restoration initiative. Chances are that
a well-thought-out planning and design process will
address most, if not all, the information needs for
evaluation or certification of permit applications.
Federal issuance of a permit triggers the need for
compliance with the National Environmental Policy
Act (see National Environmental Policy Act
Considerations/
Figure 5.7: Field volunteers. Volunteers assist-
ing in the restoration effort can be an effective
way to combat financial constraints.
Source: C . Zabawa.
various levels of field work, as well as to
serve as knowledgeable experts for the
effort; costing the initiative in phases
that are affordable; and other creative
approaches (Figure 5.7). Logistical sup-
port by a local sponsor or community
in the form of labor, boats, and other
equipment should not be overlooked.
Not all restorations are complex or
costly. Some might be as simple as a
slight change in the way that resources
are managed in and along the stream
corridor, involving only minor costs.
Other restorations, however, may re-
quire substantial funds because of the
complexity and extent of measures
needed to achieve the planned restora-
tion goals.
5-10
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
National Environmental Policy Act
Considerations
7776 National Environmental Policy Act (NEPA) of
1969 established the nation's policy to protect and
restore the environment and the federal responsi-
bility to use "all practicable means and measures ...
to create and maintain conditions under which
man and nature can exist in productive harmony,
and fulfill the social and economic and other
requirements of present and future generations of
Americans." NEPA focuses on major federal actions
with the potential to significantly affect the human
environment. The Council on Environmental
Quality's regulations implementing NEPA require
the federal agency taking action to develop alter-
natives to a proposed action, to analyze and com-
pare the impacts of each alternative and the pro-
posed action, and to keep the public informed and
involved throughout the project planning and
implementation. Although NEPA does not mandate
environmentally sound decisions, it has established
a decision-making process that ultimately encour-
ages better, wiser, and fully informed decisions.
When considering restoration of a stream corridor,
it is important to determine early on whether a
federal action will occur. Federal actions that might
be associated with a stream corridor restoration
initiative include, but are by no means limited to, a
decision to provide federal funds for a restoration
initiative, a decision to significantly alter operation
and maintenance of federal facilities on a river sys-
tem, or the need for a federal permit (e.g., a Clean
Water Act Section 404 permit for placement of
dredged or fill material in waters of the United
States).
In addition, many states have environmental
impact analysis statutes patterned along the same
lines as NEPA. Consultation with state and local
agencies should occur early and often throughout
the process of developing a stream corridor
restoration initiative. Jointly prepared federal and
state environmental documentation is routine in
some states and is encouraged.
The federal requirement to comply with NEPA
should be integrated with the planning approach
for developing a restoration plan. When multiple
federal actions are required to fully implement a
restoration initiative, the identity of the lead feder-
al agency(s) and cooperating agencies should be
established. This will facilitate agency adoption
of the NEPA document for subsequent decision
making.
Institutional and Legal Issues
Each restoration effort has its own
unique set of regulatory requirements,
which can range from almost no re-
quirements to a full range of local,
county, state, and federal permits.
Properly planned restoration efforts
should meet or exceed the intent of
both federal and non-federal require-
ments. Restoration planners should
contact the appropriate local, state, and
federal agencies and involve them early
in the process to avoid conflicts with
these legal requirements.
Typical institutional and legal require-
ments cover a wide range of issues. Lo-
cally, restoration planners must be
concerned with zoning permits and
state and county water quality permits.
Most federally sponsored and/or
funded initiatives require compliance
with the National Environmental Policy
Act and the Endangered Species Act. Ini-
tiatives that receive federal support
must comply with the National Historic
Preservation Act and the Wild and
Scenic Rivers Act. Permits might also be
required from the US Army Corps of
Developing Restoration Goals and Objectives
5-11
-------
Example Goals and Objectives
The following is an excerpt from of a restoration plan
used for restoration of Wheaton Branch, a severely
degraded urban stream in Maryland. The goal of the
project was to control storm water flows and improve
water quality.
OBJECTIVES ALTERNATIVES
(1) Remove urban
pollutants
(2) Stabilize channel
bundles
Upstream pond retrofit
Install a double-wing
deflector, imbricated riprap,
and brush
(3) Control hydro logic
regime retrofit
(4) Recolonize stream
community
Adapted from Center for Watershed Protection 1995.
Upstream storm water
management pond
Fish reintroduction
Engineers under Section 404 of the
Clean Water Act and Section 10 of the
Rivers and Harbors Act of 1899.
Defining Restoration Goals
Restoration goals should be defined by
the decision maker(s) with the consen-
sus of the advisory group and input
from the interdisciplinary technical
team(s) and other participants. As
noted earlier, these goals should be an
integration of two important groups of
factors:
Desired future condition (ecological
reference condition).
Social, political, and economic
values.
Considering Desired Future
Condition
As discussed earlier, the desired eco-
logical future condition of the stream
corridor is frequently based on pre-
development conditions or some com-
monly accepted idea of how the natural
stream corridors looked and functioned.
Consequently, it represents the ideal sit-
uation for restoration, whether or not
this reference condition is attainable.
This ideal situation has been given the
term "potential," and it may be de-
scribed as the highest ecological status
an area can attain, given no political,
social, or economic constraints
(Prichard et al. 1993). When applied to
the initiative, however, this statement
might require modification to provide
realistic and more specific goals for
restoration.
Factoring In Constraints and
Issues
In addition to the desired future ecolog-
ical condition, definition of restoration
goals must also include other considera-
tions. These other factors include the
important political, social, and eco-
nomic values as well as issues of scale.
When these considerations are factored
into the analysis, realistic project goals
can be identified. The goals provide the
overall purpose for the restoration effort
and are based on a stream corridor's ca-
pability or its ideal ecological condition.
Defining Primary and Secondary
Restoration Coals
The identification of realistic goals is a
key ingredient for restoration success
since it sets the framework for adaptive
management within a realistic set of ex-
pectations. Unrealistic restoration goals
create unrealistic expectations and po-
tential disenchantment among stake-
5-12
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
holders when those expectations are
unfulfilled.
In defining realistic restoration goals, it
might be helpful to divide these goals
into two separate, yet connected, cate-
goriesprimary and secondary.
Primary Restoration Goals
Primary goals should follow from the
problem/opportunity identification and
analysis, incorporate the participants'
vision of the desired future condition,
and reflect a recognition of project con-
straints and issues such as spatial scale,
needs found in baseline data collection,
practical aspects of budget and human
resources requirements, and special re-
quirements for certain target or endan-
gered species. Primary goals are usually
the ones that initiated the project, and
they may focus on issues such as bank
stabilization, sediment management,
upland soil and water conservation,
flood control, improved aquatic and
terrestrial habitat, and aesthetics.
Secondary Restoration Goals
Secondary goals should be developed
to either directly or indirectly support
the primary goals of the restoration ef-
fort. For example, hiring displaced
forestry workers to install conservation
practices in a forested watershed or re-
gion could serve the secondary goal of
revitalizing a locally depressed econ-
omy, while also contributing to the pri-
mary goal of improving biodiversity in
the restoration area.
Defining Restoration
Objectives
Objectives give direction to the general
approach, design, and implementation
of the restoration effort. Restoration ob-
jectives should support the goals and
also flow directly from problem/oppor-
tunity identification and analysis.
Cultural Resource Considerations and
the National Historic Preservation Act
Cultural resources also need to be considered during the
restoration process. Any activity that involves federal
funds, approval, licenses, or permits, or that occurs on
federal land, must comply with Section 106 of the
National Historic Preservation Act (NHPA), as amended,
and its implementing regulations (Protection of Historic
and Cultural Properties, Title 36 of the Code of Federal
Regulations, Part 800) published by the national
Advisory Council on Historic Preservation (ACHP).
Compliance with Section 106 is the responsibility of the
federal agency and, with rare exception, cannot be dele-
gated. Section 106 requires that the ACHP be provided a
reasonable opportunity to comment on actions that
might affect historic properties listed in or eligible for the
National Register of Historic Places.
Every state has a State Historic Preservation Office,
which can provide information about known cultural
resources in an assistance area and can assist with quick-
ly establishing contacts for needed expertise and outlin-
ing various requirements that will or might apply.
Restoration objectives should be de-
fined in terms of the same conditions
identified in the problem analysis and
should specifically state which impaired
stream corridor condition(s) will be
moved toward which particular refer-
ence level or desired condition(s). The
reference conditions provide a gauge
against which to measure the success of
the restoration effort; restoration objec-
tives should therefore identify both im-
paired stream corridor conditions and a
quantitative measure of what consti-
tutes unimpaired (restored) conditions.
Restoration objectives expressed in
terms of measurable stream corridor
conditions provide the basis for moni-
toring the success of the project in
meeting condition objectives for the
stream corridor.
Developing Restoration Goals and Objectives
5-13
-------
Concepts Useful in Defining
Restoration Goals and Objectives
Value: Social/economic values associated with a
change from one set of conditions to another.
Often, these values are not economic values, but
rather amenity values such as improved water
quality, improved habitat for native aquatic or
riparian species, or improved recreational experi-
ences. Because stream corridor restoration often
requires a monetary investment, the benefits of
restoration need to be considered not only in
terms of restoration costs, but also in terms of val-
ues gained or enhanced.
Tolerance: Acceptable levels of change in condi-
tions in the corridor. Two levels of tolerance are
suggested:
(1) Variable "management" tolerance that is
responsive to social concerns for selected areas.
(2) Absolute "resource" tolerance or minimal
acceptable permanent resource damage.
Stream corridors in need of restoration usually (but
not always) exceed these tolerances.
Vulnerability: How susceptible a stream's present
condition is to further deterioration if no new
restoration actions are implemented. It can be con-
ceptualized as the ease with which the system
might move away from dynamic equilibrium. For
example, an alpine stream threatened by a head-
cut induced by a poorly placed culvert might be
extremely vulnerable to subsequent incision.
Conversely, a forested stream that has sluiced to
bedrock because large woody debris was lost from
the system might be much less vulnerable to fur-
ther deterioration.
Responsiveness: How readily or efficiently
restoration actions will achieve improved stream
corridor conditions. It can be conceptualized as the
ease with which the system can be moved toward
dynamic equilibrium. For example, a range/and
stream that has become excessively wide and shal-
low might respond very rapidly to grazing man-
agement by establishing a more natural cross sec-
tion that is substantially narrower and deeper. On
the other hand, an agricultural stream that has
deeply incised following channelization might not
readily reestablish grade or channel pattern in
response to improved watershed or riparian vege-
tation conditions.
Self-Sustainability: The degree to which the
restored stream can be expected to continue to
maintain its restored (but dynamic) condition. The
creation or establishment of dynamic equilibrium
should always be a goal. However, it might be that
intensive short-term maintenance is necessary to
ensure weeds and exotic vegetation do not get a
foothold. The short-term and longer-term goals
and objectives to ensure sustainability need to be
carefully considered relative to funding, proximity
of the site to population concentrations, and care-
takers.
5-14
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
Restoration of the
Elwha River Ecosystem
The construction of numerous hydropower pro-
jects fueled the economic growth of the
Pacific Northwest during the early 1900s. With the
seemingly inexhaustible supply of anadromous
salmonids, little care was taken to reduce or miti-
gate the consequent impacts to these fish
(Hoffman and Winter 1996). Two hydropower
dams built on the Elwha River, on Washington's
Olympic Peninsula, were no exception.
The 108 ft. high Elwha Dam (Figure 5.8) was built
from 1910-13 about five miles from the river
mouth. Although state law required a fishway, one
was not built. As a result, salmon and steelhead
populations immediately declined, some to extinc-
tion, and remaining populations have been con-
fined to the lower five miles ever since. The 210 ft.
high Glines Canyon Dam (Figure 5.9) was built
from 1925-27 about eight miles upstream of the
first dam, also without fish passage facilities. Glines
was licensed for a period of 50 years in 1925 while
the Elwha Dam has never been licensed.
In 1968, the project owner filed a license applica-
tion for Elwha Dam and filed a relicense applica-
tion for the Glines Canyon Dam in 1973. The
Federal Energy Regulatory Commission (FERC) did
not actively pursue the licensing of these two proj-
ects until the early 1980s when federal and state
agencies, the Lower Elwha Klallam Tribe (Tribe),
and environmental groups filed petitions with FERC
to intervene in the licensing proceeding. The
option of dam removal to restore the decimated
fish runs was raised in most of these petitions, and
FERC addressed dam removal in a draft environ-
mental impact statement (EIS). Nonetheless, it was
apparent that disagreements remained over
numerous issues, and that litigation could take a
decade or more.
Congressional representatives offered to broker a
solution. In October 1992, President George Bush
signed Public Law 102-495 (the Elwha River
Ecosystem and Fisheries Restoration Act; the Elwha
Act), which is a negotiated settlement involving all
parties to the FERC proceeding. The Elwha Act voids
Figure 5.8: Elwha Dam. Fish passages were not construct-
ed when the dam was built in 1910-1913.
FERC's authority to issue long-term licenses for
either dam, and it confers upon the Secretary of the
Interior the authority to remove both dams if that
action is needed to fully restore the Elwha River
ecosystem and native anadromous fisheries. In a
report to the Congress (DOI et al. 1994), the
Secretary concluded that dam removal was neces-
sary to meet the goal of the Elwha Act. Subse-
quently, Interior completed the EIS process FERC had
begun but using the new standard of full ecosystem
restoration rather than "balancing" competing uses
as FERC is required to do (NFS 1995).
Interior analyzed various ways to remove the dams
and manage the 18 million cubic yards (mcy) of
sediments that have accumulated in the two reser-
voirs since dam construction. The preferred alter-
native for the Glines Canyon Dam is to spill the
reservoir water over successive notches construct-
ed in the concrete gravity-arch section, allowing
layers of the dam to be removed with a crane
under dry conditions (NFS 1996). Standard dia-
mond wire-saw cutting and blasting techniques
are planned. Much of the dam, including the left
and right side concrete abutments and spillway,
will be retained to allow for the interpretation of
this historic structure.
The foundation of the Elwha Dam failed during
reservoir filling in 1912, flooding downstream
areas such as the Tribe's reservation at the mouth
of the river. A combination of blasted rock, fir
Developing Restoration Goals and Objectives
5-15
-------
mattresses, and other fill was used to plug the leak
(NFS 1996). To avoid a similar failure during
removal, the reservoir will be partially drained and
the river diverted into a channel constructed
through the bedrock footing of the left abutment.
This will allow the fill material and original dam
structure to be removed under dry conditions.
Following removal of this material, the river will be
diverted back to its historic location and the
bedrock channel refilled. Since the Elwha Dam was
built in an area that is religiously and culturally
important to the Tribe, all structures will be
removed.
The 18 mcy of accumulated sediment consists of
about 9.2 mcy of silt and clay (<0.075 mm), 6.2
mcy of sand (0.075-<5 mm), 2.0 mcy of gravel
(5-<75 mm), and .25 mcy of cobbles (75-<300
mm). The coarse material (i.e., sand and larger) is
considered a resource that is lacking in the river
below the dams, the release of which will help
restore the size and function of a more natural
and dynamic river channel, estuary, and nearshore
marine areas. The silt- and day-sized particles are
also reduced in the lower river, but resuspension of
this material may cause the loss of aquatic life and
adversely affect water users downstream for the
approximately two to three years this process is
expected to last (NFS 1996). Nevertheless, the pre-
ferred alternative incorporates the natural erosive
and transport capacity of the river to move this
material downstream, although roughly half of the
fine and coarse materials will remain in the newly
dewatered reservoir areas. Water quality and fish-
eries mitigation actions are planned to reduce the
impacts of sediment releases during and following
dam removal. Revegetation actions will be imple-
mented on the previously logged slopes for stabi-
lization purposes and to accelerate the achieve-
ment of old-growth characteristics. The old reser-
voir bottoms will be allowed to revegetate natural-
ly; "greenup" should occur within three to five
years.
Figure 5.9: Glines Canyon Dam. (a) Before removal and
(b) simulation after removal.
Following the removal of both dams, the salmon
and steelhead runs are expected to total about
390,000 fish, compared to about 12,000 to
20,000 (primarily hatchery) fish. These fish will
provide over 800,000 pounds of carcass biomass
(NFS 1995). About 13,000 pounds of this biomass
is marine-derived nitrogen and phosphorous, the
benefits of which will cascade throughout the
aquatic and terrestrial ecosystem. The vast majority
of wildlife species are expected to benefit from the
restoration of this food resource and the recovery
of over 700 acres of important lowland habitat.
Restoration of the fish runs will also support the
federal government's trust responsibility to the
Tribe for its treaty-reserved harvest rights. More
wetlands will be recovered than will be lost from
draining the reservoirs.
5-16
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
As in the case of restoration goals, it is
imperative that restoration objectives be
realistic for the restoration area and be
measurable. Objectives must therefore
be based on the site's expected capabil-
ity and not necessarily on its unaltered
natural potential. It is much more use-
ful to have realistic objectives reflecting
stream corridor conditions that are
both achievable and measurable than
to have vague, idealistic objectives re-
flecting conditions that are neither.
For example, an overall restoration goal
might be to improve fish habitat. Sev-
eral supporting objectives might in-
clude the following:
Improve water temperature by pro-
viding shade plants.
Construct an instream structure to
provide a pool as a sediment trap.
Work with local landowners to
encourage near-stream conservation
efforts.
If these objectives were to be used as
success criteria, however, they would re-
quire more specific, measurable word-
ing. For example, the first objective
could be written to state that button-
bush planted along streambanks exhibit
a 50 percent survival rate after three
growing seasons and are not less than
5 feet in height. This vegetative cover
results in a net reduction in water tem-
perature within the stream. It should be
noted that this issue of success or evalu-
ation criteria is critical to stream corri-
dor restoration. This is explored in
more detail in Chapters 6 and 9.
5.B Alternative Selection and Design
The selection of technically feasible al-
ternatives and subsequent design are in-
tended to solve the identified problems,
realize restoration opportunities, and
accomplish restoration goals and objec-
tives. Alternatives range from making
minor modifications and letting nature
work to total reconstruction of the
physical setting. An efficient approach is
to conceptualize, evaluate, and select
general solutions or overall strategies
before developing specific alternatives.
This section focuses on some of the
general issues and considerations that
should be taken into account in the se-
lection and design of stream corridor
restoration alternatives. It sets the stage
for the more detailed presentation of
restoration design in Chapter 8 of this
document.
Important Factors to Consider
in Designing Restoration
Alternatives
The design of restoration alternatives is
a challenging process. In developing al-
ternatives, special consideration should
be given to managing causes as op-
posed to treating symptoms, tailoring
restoration design to the appropriate
scale (landscape/corridor/stream/
reach), and other scale-related issues.
Managing Causes vs. Treating
Symptoms
When developing restoration alterna-
tives, three questions regarding the fac-
tors that influence conditions in the
stream corridor must be addressed.
These are critical questions in determin-
ing whether a passive, nonstructural al-
ternative is appropriate or whether a
more active restoration alternative is
needed.
FAST
FORWARD
Preview
Chapter 8's
restoration
design section.
Alternative Selection and Design
5-17
-------
Alternative Selection and Design
Considerations
Supporting Analyses for Selecting Alternatives
Feasibility study
Cost-effectiveness analysis
Risk assessment
Environmental impact analysis
Factors to Consider in Alternative Design
Managing causes vs. treating symptoms
Landscape/Watershed vs. corridor reach
Other spatial and temporal considerations
1. What have been the implications of
past management activities in the
stream corridor (a cause-effects
analysis)?
2. What are the realistic opportunities
for eliminating, modifying, mitigat-
ing, or managing these activities?
3. What would be the response of
impaired conditions in the corridor if
these activities could be eliminated,
modified, mitigated, or managed?
If the causes of impairment can realisti-
cally be eliminated, complete ecosystem
restoration to a natural or unaltered
condition might be a feasible objective
and the focus of the restoration activity
will be clear. If the causes of impair-
ment cannot realistically be eliminated,
it is critical to identify what options
exist to manage either the causes or
symptoms of altered conditions and
what effect, if any, those management
options might have on the subject
conditions.
If it is not feasible to manage the
cause(s) of impaired conditions, then
mitigating the impacts of disturbance(s)
is an alternative method of implement-
ing sustainable stream corridor restora-
tion. By choosing mitigation, the focus
of the restoration effort might then be
on addressing only the symptoms of
impaired conditions.
When disturbance cannot be fully elim-
inated, a logical planning process must
be used to develop alternative manage-
ment options. For example, in analyz-
ing bank erosion, one conclusion might
be that accelerated watershed sediment
delivery has produced lateral instability
in the stream system, but modification
of land-use patterns causing the prob-
lem is not a feasible management op-
Figure 5.10: Streambank erosion. In designing
alternatives for bank erosion it is important to
assess the feasibility of addressing the cause of
the problem (e.g., modify land uses) or treat-
ing the symptom (e.g., install bank-erosion
control structures).
5-18
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
tion at this time (Figure 5.10). It might
therefore still be possible to develop a
channel erosion condition objective
and to identify treatments such as engi-
neered or soil-bioengineered bank ero-
sion control structures, but it will not
be possible to return the stream corri-
dor to its predisturbance condition.
Other resource implications of in-
creased watershed sediment delivery
will persist (e.g., altered substrate con-
ditions, modified riffle-pool structure,
and impaired water quality).
It is important to note that in treating
causes, a danger always remains that in
treating one symptom of impairment,
another unwanted change in stream
corridor conditions will be triggered.
To continue with the erosion example,
bank hardening in one location might
interfere with sedimentation processes
critical to floodplain and riparian habi-
tats, or it might simply transfer lateral
instabilities from one location in a
stream reach to some other location.
Landscape/Watershed vs.
Corridor/Reach
The design and selection of alternatives
should address the following relation-
ships:
Reach to stream
Stream to corridor
Corridor to landscape
Landscape to region
Characterizing those relationships re-
quires a good inventory and analysis of
conditions and functions on all levels
including stream structure (both vertical
and horizontal) and human activities
within the watershed.
The restoration design should include
innovative solutions to prevent or miti-
gate, to the extent possible, negative im-
pacts on the stream corridor from
Core Elements of Restoration
Alternatives
At a minimum, alternatives should contain a manage-
ment summary of proposed activities, including an
overview of the following elements:
m Detailed site description containing relevant discussion
of all variables having a bearing on that alternative.
Identification and quantification of existing stream
corridor conditions.
Analysis of the various causes of impairment and the
effect of management activities on these impaired
conditions and causes in the past.
Statement of specific restoration objectives, expressed
in terms of measurable stream corridor conditions and
ranked in priority order.
Preliminary design alternatives and feasibility analysis.
Cost-effectiveness analysis for each treatment or
alternative.
Assessment of project risks.
Appropriate cultural and environmental clearances.
Monitoring plan linked to stream corridor conditions.
Anticipated maintenance needs and schedule.
Alternative schedule and budget.
Provision to make adjustments per adaptive
management.
upstream land uses. Land use activities
within a watershed may vary widely
within generalized descriptions of
urban, agricultural, recreation, etc. For
example, urban residential land use
could comprise neighborhoods of man-
icured lawns, exotic plants, and roof
runoff directed to nearby storm sewers.
Or residential use might be composed
of neighborhoods with native cover
types, overhead canopy, and roof runoff
flowing to wetland gardens. Restoration
Alternative Selection and Design
5-19
-------
Review Chap-
ter 1's Dynamic
Equilibrium
section.
design should address the storm water
flows, pollutants, and sediment load-
ings from these different land uses that
could impact the stream corridor.
Since it is usually not possible to re-
move the human activities that disturb
stream corridors, where seemingly detri-
mental activities like gravel mining,
damming, and road crossings are pres-
ent in the watershed or in the stream
corridor itself, restoration design should
provide the best possible solutions for
maintaining optimum stream corridor
functions while meeting economic and
social objectives (Figure 5.11).
Other Time and Space
Consider a tions
Restoration design flexibility is critical to
long-term success and achievement of
dynamic equilibrium. Beyond the
stream corridor is an entire landscape
that functions in much the same way as
the corridor. When designing and
Figure 5.11: Stream buffers in agricultural
areas. It is not possible to remove human
activity from the corridor. Design alternatives
should provide the best possible way of achiev-
ing the desired goals without negating the
activity.
choosing alternatives, it is important to
consider the effect of the restoration on
the entire landscape. A wide, connected,
and diverse stream corridor will en-
hance the functions of the landscape as
well as those of the corridor. Connectiv-
ity and width also increase the resiliency
of the stream corridor to landscape per-
turbations and stress, whether induced
naturally or by humans.
Alternatives should also be relatively
elastic, although time and physical
boundaries might not be so flexible. As
discussed in Chapter 1, dynamic equi-
librium requires that the restoration
design be allowed an opportunity to
mold itself to the changing conditions
of the corridor over time and to the
disturbances that are a part of the nat-
ural environment. Alternatives should
be weighed against one another by
considering how they might react to in-
creasing land pressures, climate
changes, and natural perturbations.
Structure should be planned to provide
necessary functions at each phase of
the corridor's development.
A possible restoration design concept
is Forman and Godron's (1986) "string
of lights." Over time, the variations
among landscape elements mean that
some provide more opportunities for
desired functions than others. A stream
corridor connection provides a path-
way through the landscape matrix such
that it can be thought of as a string of
lights in which some turn on and burn
brightly for a time, while others fade
away for a short time (Figure 5.14). As
the string between these lights, the
stream corridor is critical to the long-
term stability of landscape functions.
Alternatives could therefore fit the
metaphor of a string of lights to sus-
tain the corridor through time.
5-20
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
Supporting Analyses for
Selecting Restoration
Alternatives
Once the restoration alternatives have
been defined, the next step is to evalu-
ate all the feasible alternatives and
management options. In conducting
this evaluation it is important to apply
several different screening criteria that
allow the consideration of a diverse
number of factors. In general, the appli-
cation of the following supporting ana-
lytical approaches ensures the selection
of the best alternative or group of alter-
natives for the restoration initiative:
Cost-effectiveness and incremental
cost analysis
Evaluation of benefits
Risk assessment
Environmental impact analysis
Cost-Effectiveness and
Incremental Cost Analyses
In its National Strategy for the Restora-
tion of Aquatic Ecosystems, the Na-
tional Research Council (NRC) states
that, in lieu of benefit-cost analysis, the
evaluation and ranking of restoration
alternatives should be based on a
framework of incremental cost analysis:
"Continually questioning the value of
additional elements of a restoration by
asking whether the actions are 'worth'
their added cost is the most practical
way to decide how much restoration is
enough" (NRC 1992). As an example,
the Council cites the approach where
"a justifiable level [of output] is chosen
in recognition of the incremental costs
of increasing [output] levels and as part
of a negotiation process with affected
interests and other federal agencies"
(NRC 1992).
As described below, cost-effectiveness
analysis is performed to identify the
least-cost solution for each possible
Figure 5.14: "String of lights." Patches along
the stream corridor provide habitat in an agri-
cultural setting.
Source: C. Zabawa.
level of nonmonetary output under
consideration. Subsequent incremental
cost analysis reveals the increases in
cost that accompany increases in the
level of output, asking the question
"As we increase the scale of this project,
is each subsequent level of additional
output worth its additional cost?"
Data Requirements: Solutions, Costs,
and Outputs
Cost-effectiveness and incremental cost
analyses may be used for any scale of
planning problem, ranging from local,
site-specific problems to problems at
the more extensive watershed and
ecosystem scales. Regardless of the
problem-solving scale, three types of
data must be obtained before conduct-
ing the analyses: a list of solutions and,
for each solution, estimates of its eco-
system or other nonmonetary effects
(outputs) and estimates of its economic
effects (costs).
The term "solutions" is used here to
refer generally to techniques for
Alternative Selection and Design
5-21
-------
Meander Reconstruction on the
J. Bar S. Winter Feeding Area
January 1, 1997, was an eventful time for
Asotin Creek, Washington, residents. In a peri-
od of less than a year, two large flood events
occurred, causing extreme damage at numerous
sites throughout the watershed.
The ordinary high flow (often referred to as chan-
nel forming or bankfull flow) is the natural size
channel a river will seek, over time. Asotin Creek's
flows exceeded the ordinary high flow 10 times at
Asotin and Headgate parks.
One impacted site is on the South Fork of Asotin
Creek. This site, referred to as the J. Bar S. winter
feeding site (Figure 5.12) and owned by Jake and
Dan Schlee, received floods more than 10 times
the ordinary high flow. Previous to January 1, the
stream was located over a hundred feet away
from the haysheds and feeding area. When large
amounts of rock, cobble, and gravel collapsed
into the right side of the stream corridor, the
entire channel was directed toward the winter
feeding area and hayshed. This redirection of
flood flows undermined and eroded away thou-
sands of tons of valuable topsoil and property,
threatening the loss of the hayshed and corral.
Fences and alternative water sources were
destroyed. The challenges for stream restoration
at this site were numerous because of the poten-
tial bridge constriction at the bottom, excessive
downcutting, and limited area within which to
work (Figure 5.13).
The Asotin County Conservation District put an
interdisciplinary team together in the spring of
1997 to develop a plan and alternative for the J.
Bar S. site. An innovative approach referred to as
meander reconstruction was proposed by the
interdisciplinary team to correct the problem and
restore some natural capabilities of the stream. It
was accepted by the landowners and Asotin
County Conservation District. Some natural capa-
bilities are the dissipation of flood energy over
floodplains and maintenance of a stable ordinary
high flow channel.
Figure 5.12: The J. Bar S. winter feeding area. This area
received floods more than W times the ordinary high
flow.
Additional benefits to the approach would be to
reestablish proper alignment with the bridge and
restore fish habitat. This alternative was installed
within the last 2 weeks of September 1997. Care
was used to move young steelhead out of the old
channel while the new meandering channel was
built. Other practices on site such as alternative
water sources and fencing are soon to follow.
The meander reconstruction was designed to
address both the landowners' concerns and
stream processes. Although on-site stream
restoration cannot resolve problems higher up in
the watershed, it can address immediate concerns
regarding fish habitat and streambank stability.
Numerous pools with woody debris were intro-
duced to enhance salmon rearing and resting
habitat. The pools were designed and set to a
scour pattern unique to this stream type. This
meander reconstruction is the first of its kind in
the state of Washington.
5-22
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
Figure 5.13: South Fork ofAsotin Creek restoration site, (a) Before reconstruction and (b) after reconstruction.
The principal funding for this project was provid-
ed by the Bonneville Power Administration (BPA)
(Table 5.1). The BPA funds are used to help
implement the Asotin Creek Model Watershed
Plan, which is part of the Northwest Power
Planning Council's "Strategy for Salmon." The
moneys for funding by BPA are generated from
power rate payers in the Northwest. The purpose
for funding is to improve the fish habitat compo-
nent of the "Strategy for Salmon," which is one
of the four elements referred to as the four H's
harvest management, hatcheries and their prac-
tices, survival at hydroelectric dams, and fish habi-
tat improvement.
Table 5.1: Project costs for J. Bar S. winter feeding area meander reconstruction and upstream revetments.
Reconstruction meanders
Upstream revetments
Fencing
Riparian/streambank plantings and potential operation and maintenance
(to be completed)
Note: Original estimate in April 1997 was $26,600
$10,200
$2,800
$400
$3,500
Alternative Selection and Design
5-23
-------
The Instream Flow Incremental
Methodology
The Instream Flow Incremental Methodology (IFIM)
is designed for river system management. IFIM is
composed of models linked to describe the spatial
and temporal habitat features of a given river
(Figure 5.15). It uses hydrologic analyses to
describe, evaluate, and compare water use
throughout a river system to understand the limits
of water supply. Its organizational framework is
useful for evaluating and formulating alternative
water management options. Ultimately, the goal of
any IFIM application is to ensure the preservation
or enhancement of fish and wildlife resources.
Emphasis is placed on displaying data from several
years to understand variability in both water supply
and habitat.
IFIM is meant to be implemented in five sequential
phasesproblem identification, study planning,
study implementation, alternatives analysis, and
problem resolution. Each phase must precede the
remaining phases, though iteration is necessary for
complex projects.
Problem Identification
The first phase has two partsa legal-institutional
analysis and a physical analysis. The legal-institu-
tional analysis identifies all affected or interested
parties, their concerns, information needs, relative
influence or power, and the potential decision
process (e.g., brokered or arbitrated). The physical
analysis determines the physical location and geo-
graphic extent of probable physical and chemical
changes to the system and the aquatic resources
yes
start
need
more work
now?
o
yes
feasible?
institutional
analysis
model
stop
formulate
alternatives
strategy
design
technical
scoping
Figure 5.15: Overview of the
instream flow incremental
methodology. IFIM describes
the spatial and temporal habi-
tat features of a given river.
micro-
habitat
model
macro-
habitat
model
total
habitat
model
network
habitat
model
5-24
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
of greatest concern, along with their respective
management objectives.
Study Planning
The study planning phase identifies information
needed to address project concerns, information
already available, information that must be
obtained, and data and information collection
methods. Study planning should result in a con-
cise, written plan that documents all aspects of
project execution and costs. It should also identify
pertinent temporal and spatial scales of evaluation.
Hydrologic information chosen to represent the
baseline or reference condition should be reexam-
ined in detail during this phase to ensure that bio-
logical reference conditions are adequate to evalu-
ate critical life history phases of fish populations.
Study Implementation
The third phase consists of several sequential activ-
itiesdata collection, model calibration, predictive
simulation, and synthesis of results. Data are col-
lected for physical and chemical water quality,
habitat suitability, population analysis, and hydro-
logic analysis. IFIM relies heavily on models
because they can be used to evaluate new projects
or new operations of existing projects. Model cali-
bration and quality assurance are key during this
phase to obtain reliable estimates of the total habi-
tat available for each life stage of each species
over time.
Alternatives Analysis
The alternatives analysis phase compares all alter-
natives, including a preferred alternative and other
alternatives, with the baseline condition and can
lead to new alternatives that meet the multiple
objectives of the involved parties. Alternatives are
examined for:
m Effectiveness: Are objectives sustainable?
Physical feasibility: Are water supply limits
exceeded?
Risk: How often does the biological system
collapse?
Economics: What are the costs and benefits?
Problem Resolution
This final phase includes selection of the preferred
alternative, appropriate mitigation measures, and a
monitoring plan. Because biological and economic
values differ, data and models are incomplete or
imperfect, opinions differ, and the future is uncer-
tain, IFIM relies heavily on professional judgment
by interdisciplinary teams to reach a negotiated
solution with some balance among conflicting
social values.
A monitoring plan is necessary to ensure compli-
ance with the agreed-upon flow management
rules and mitigation measures. Post-project moni-
toring and evaluation should be considered when
appropriate and should be mandatory when chan-
nel form will respond strongly to the selected new
flow and sediment transport conditions.
For More Information on IFIM
The earliest and best documented application of
IFIM involved a large hydroelectric project on the
Terror River in Alaska (Lamb 1984, Olive and Lamb
1984). Another application involved a Section 404
permit on the James River, Missouri (Cavendish and
Duncan 1986). Nehring and Anderson (1993) dis-
cuss the habitat bottleneck hypothesis. Stalnaker
et al. (1996) discuss the temporal aspects of
instream habitats and the identification of poten-
tial physical habitat bottlenecks. Relations between
habitat variability and population dynamics are
described by Bovee et al. (1994). Thomas and
Bovee (1993) discuss habitat suitability criteria.
IFIM has been used widely by state and federal
agencies (Reiser et al. 1989, Armour and Taylor
1991). Additional references and information on
available training can currently be obtained from
the Internet at http://www.mesc.nbs.gov/rsm/
IFIM.html.
Alternative Selection and Design
5-25
-------
accomplishing planning objectives. For
example, if faced with a planning objec-
tive to "Increase waterfowl habitat in
the Blue River Watershed," a solution
might be to "Construct and install 50
nesting boxes in the Blue River riparian
zone." Solutions may be individual
management measures (for example,
clear a channel, plant vegetation, con-
struct a levee, or install nesting boxes),
plans (various combinations of man-
agement measures), or programs (vari-
ous combinations of plans, perhaps at
the landscape scale).
Cost estimates for a solution should in-
clude both financial implementation
costs and economic opportunity costs.
Implementation costs are direct finan-
cial outlays, such as costs for design,
real estate acquisition, construction,
operation and maintenance, and moni-
toring. The opportunity costs of a solu-
tion are any current benefits available
with the existing state of the watershed
that would be foregone if the solution
were implemented. For example, restor-
ation of a river ecosystem might require
that some navigation benefits derived
from an existing river channel be given
up to achieve the desired restoration. It
is important that the opportunity costs
of foregone benefits be accounted for
and brought to the table to inform the
decision-making process.
The level to which a solution accom-
plishes a planning objective is mea-
sured by the solution's output estimate.
Historically, environmental outputs
have been expressed as changes in pop-
ulations (waterfowl and fish counts, for
example) and in physical dimensions
(acres of wetlands, for example). In re-
cent years, output estimates have been
derived through a variety of environ-
mental models such as the U.S. Fish
and Wildlife Service's Habitat Evalua-
tion Procedures (HEP), which summa-
rize habitat quality and quantity for
specific species in units called "habitat
units." Models for ecological communi-
ties and ecosystems are in the early
stages of development and application
and might be more useful at the water-
shed scale.
Cost-Effectiveness Analysis
In cost-effectiveness analysis, solutions
that are not rational (from a production
perspective) are identified and can be
screened out from inclusion in subse-
quent incremental cost analysis.
Cost-effectiveness screening is fairly
straightforward when monetary values
are easily assigned. The "output" or
nonmonetary benefits of restoration ac-
tions are more difficult to evaluate.
These benefits may include changes in
intangible values of habitat, aesthetics,
nongame species populations, and oth-
ers. The ultimate goal, however, is to be
able to weigh objectively all of the ben-
efits of the restoration against its costs.
There are two rules for cost-effectiveness
screening. These rules state that solu-
tions should be identified as inefficient
in production, and thus not cost-effec-
tive, if (1) the same level of output
could be produced by another solution
at less cost or (2) a greater level of out-
put could be produced by another solu-
tion at the same or less cost.
For example, look at the range of solu-
tions in Figure 5.16. Applying Rule 1,
Solution C is identified as inefficient in
production: why spend $3,600 for 100
units of output when 100 units can be
obtained for $2,600 with Solution B, a
savings of $1,000? In this example, So-
lution C could also be screened out by
the application of Rule 2: why settle for
100 units of output with Solution C
when 20 additional units can be pro-
vided by Solution E at the same cost?
Also by applying Rule 2, Solution D is
screened out: why spend $4,500 for 110
5-26
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
Solution I Units of Output I Total Cost ($)
0
2,000
2,600
3,600
4,500
3,600
7,000
8000
7000
S 6000
o 5000
3 4000
"" 3000
2000
0
-
F
-
>
g /
C ° E
O O
- A B0 \
- o cost effectiveness
frontier
i i i
0 80 100 120 140
Units of Output
Figure 5.16: Cost effectiveness frontier. This
graph plots the solutions' total cost (vertical
axis) against their output levels (horizontal axis).
units when 10 more units could be pro-
duced by E for $900 less cost?
Figure 5.16 shows the "cost-effective-
ness frontier" for the solutions listed in
the table. This graph, which plots the
solutions' total cost (vertical axis)
against their output levels (horizontal
axis), graphically depicts the two
screening rules. The cost-effective solu-
tions delineate the cost-effectiveness
frontier. Any solutions lying inside the
frontier (above and to the left), such as
C and D, are not cost-effective and
should not be included in subsequent
incremental cost analysis.
Incremental Cost Analysis
Incremental cost analysis is intended to
provide additional information to sup-
port a decision about the desired level
of investment. The analysis is an inves-
tigation of how the costs of extra units
of output increase as the output level
increases. Whereas total cost and total
output information for each solution is
needed for cost-effectiveness analysis,
incremental cost analysis requires data
showing the difference in cost (incre-
mental cost) and the difference in out-
put (incremental output) between each
solution and the next-larger solution.
Continuing with the previous example,
the incremental cost and incremental
output associated with each solution
are shown in Figure 5.17. Solution A
would provide 80 units of output at a
cost of $2,000, or $25 per unit. Solu-
tion B would provide an additional 20
units of output (100 - 80) at an addi-
tional cost of $600 ($2,600 - $2,000).
The incremental cost per unit (incre-
mental cost divided by incremental out-
put) for the additional 20 units B
provides over A is, therefore, $30. Simi-
lar computations can be made for solu-
tions E and F. Solutions C and D have
been deleted from the analysis because
they were previously identified as ineffi-
cient in production.
As shown in Figure 5.17, the incremen-
tal cost per unit is measured on the ver-
tical axis; both total output and
incremental output can be measured on
the horizontal axis. The distance from
the origin to the end of each bar indi-
cates total output provided by the corre-
sponding solution. The width of the bar
associated with each solution identifies
the incremental amount of output that
would be provided over the previous,
smaller-scaled solution; for example,
Solution E provides 20 more units of
output than Solution B . The height of
the bar illustrates the cost per unit of
that additional output; for example,
those 20 additional units obtainable
through Solution E cost $50 each.
Alternative Selection and Design
5-27
-------
Solution
Level of Output
Cost (S)
Total I Incremental I Total
Output I Output I Cost
180
.tt 160
= 140
1120
8100
m 80
£
60
40
20
0
0
2,000
2,600
3,600
7,000
Incremental I Incremental Cost
Cost I Incremental Output
0
2,000
600
1,000
3,400
B
20 40 60 80 100 120 140
Units of Output
0
25
30
50
Figure 5.17: Incremental cost and output display. This graph plots the cost per unit (vertical axis)
against the total output and incremental output (horizontal axis).
Decision Making"Is It Worth It?"
The table in Figure 5.17 presents cost
and output information for the range of
cost-effective solutions under considera-
tion in a format that facilitates the in-
vestment decision of which (if any)
solution should be implemented. This
decision process begins with the deci-
sion of whether it is "worth it" to im-
plement Solution A.
Figure 5.17 shows Solution A provides
80 units of output at a cost of $25 each.
If it is decided that these units of out-
put are worth $25 each, the question
becomes "Should the level of output be
increased?" To answer this question,
look at Solution B, which provides 20
more units than Solution A. These 20
additional units cost $30 each. "Are
they worth it?" If "yes," look to the next
larger solution, E, which provides 20
more units than B at $50 each, again
asking "Are they worth it?" If it is de-
cided that E's additional output is
worth its additional cost, look to F,
which provides 20 more units than E at
a cost of $170 each.
Cost-effectiveness and incremental cost
analyses will not result in the identifica-
tion of an "optimal" solution as is the
case with cost-benefit analysis. How-
ever, they do provide information that
decision makers can use to facilitate
and support the selection of a single so-
lution. Selection may also be guided by
decision guidelines such as output "tar-
gets" (legislative requirements or regu-
latory standards, for example),
minimum and maximum output
thresholds, maximum cost thresholds,
sharp breakpoints in the cost-effective-
ness or incremental cost curves, and lev-
els of uncertainty associated with the
data.
In addition, the analyses are not in-
tended to eliminate potential solutions
5-28
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
from consideration, but rather to pre-
sent the available information on costs
and outputs in a format to facilitate
plan selection and communicate the
decision process. A solution identified
as "inefficient in production" in cost-
effectiveness analysis might still be de-
sirable; the analysis is intended to make
the other options and the associated
trade-offs explicit. Reasons for selecting
"off the cost-effectiveness curve" might
include considerations that were not
captured in the output model being
used, or uncertainty present in cost and
output estimates. Where such issues
exist, it is important that they be explic-
itly introduced to the decision process.
After all, the purpose of conducting
cost-effectiveness and incremental cost
analyses is to provide more, and hope-
fully better, information to support de-
cisions about investments in
environmental (or other nonmonetary)
resources.
Evaluation of Benefits
Cost-effectiveness and incremental
cost analyses are but one approach for
evaluating restoration projects. More
broadly defined approaches, sometimes
referred to as benefit maximization, fall
into three categories (USEPA 1995a):
1. Prioritized benefits are ranked by
preference or priority, such as best,
next best, and worst. Available infor-
mation might be limited to qualita-
tive descriptions of benefits, but
might be sufficient.
2. Quantifiable benefits can be counted
but not priced. If benefits are quan-
tifiable on some common scale
(e.g., percent removal of fine sedi-
ment as an index of spawning sub-
strate improvement), a cost per unit
of benefits that identifies the most
efficient producer of benefits can be
devised (similar to the previously
described cost effectiveness and
incremental cost analyses).
3. Nonmonetary benefits can be
described in monetary terms. For
example, when restoration provides
better fish habitat than point source
controls would provide, the monetary
value of improved fish habitat (e.g.,
economic benefits of better fishing)
needs to be described. Assigning a
monetary value to game or commer-
cial species might be relatively easy;
other benefits of improved habitat
quality (e.g., improved aesthetics) are
not as easily determined, and some
(e.g., improved biodiversity) cannot
be quantified monetarily. Each bene-
fit must, therefore, be analyzed
differently.
Key considerations in evaluating bene-
fits include timing, scale, and value. The
short-term and long-term benefits of
each project must be measured. In addi-
tion, potential benefits and costs must
be considered with respect to results on
a local level versus a watershed level. Fi-
nally, there are several ways to value the
environment based on human use and
appreciation. Commercial fish values
can be calculated, recreational or sport-
fishing values can be estimated by eval-
uating the costs of travel and
expenditures, some aesthetic and im-
proved flood control values can be esti-
mated through changes in real estate
value, and social values (such as
wildlife, aesthetics, and biodiversity)
can be estimated by surveying people to
determine their willingness to pay.
Risk Assessment
Stream-corridor restoration involves a
certain amount of risk that, regardless
of the treatment chosen, restoration ef-
forts will fail. To the extent possible, an
identification of these risks for each al-
ternative under consideration is a useful
Alternative Selection and Design
5-29
-------
tool for analysis by the decision maker.
A thorough risk assessment is particu-
larly important for those large-scale
restoration efforts which involve signifi-
cant outlays of labor and money or
where a significant risk to human life or
property would occur downstream
should the restoration fail.
A primary source of risk is the uncer-
tainty associated with the quality of
data used in problem analysis or
restoration design. Data uncertainty re-
sults from errors in data collection and
analysis, external influences on resource
variables, and random error associated
with certain statistical procedures (e.g.,
regression analysis). Data uncertainty is
usually handled by application of statis-
tical procedures to select confidence in-
tervals that estimate the quality of the
data used for analysis and design.
The first source of risk is the possibility
that design conditions will be exceeded
by natural variability before the project
is established. For example, if a channel
is designed to pass a 50-year flood on
the active floodplain, but it takes 5
years to establish riparian vegetation on
that floodplain, there is a certain risk
that the 50-year flood will be exceeded
during the 5 years it takes to establish
natural riparian conditions on the
floodplain. A similar situation would
exist where a revegetation treatment re-
quires a certain amount of moisture for
vegetation establishment and assumes
the worst drought of record does not
occur during the establishment period.
This kind of risk is readily amenable to
statistical analysis using the binomial
distribution and is presented in several
existing reports on hydrologic risk (e.g.,
Van Haveren 1986).
Environmental Impact Analysis
The fact that the impetus behind any
stream corridor restoration initiative
is recovery or rehabilitation does not
necessarily mean that the proposal is
without adverse effects or public con-
troversy. Short-term and long-term ad-
verse impacts might result. For example,
implementation activity such as earth-
work involving heavy equipment might
temporarily increase sedimentation or
soil compaction. Furthermore, restora-
tion of one habitat type is probably at
the expense of another habitat type; for
example, recreating habitat to benefit
fish might come at the expense of habi-
tat used by birds.
Some alternatives, such as total exclu-
sion to an area, might be well defined
scientifically but have little social ac-
ceptability. Notwithstanding the envi-
ronmental impacts and trade-offs, both
fish and birds have active constituencies
that must be involved and whose con-
cerns must be acknowledged. Therefore,
careful environmental impact analysis
considers the potential short- and long-
term direct, indirect, and cumulative
impacts, together with full public in-
volvement and disclosure of both the
impacts and possible mitigating mea-
sures. This is no less important for an
initiative to restore a stream corridor
than for any other type of related
activity.
5-30
Chapter 5: Developing Goals, Objectives, and Restoration Alternatives
-------
Implement,
Monitor,
Evaluate,
and Adapt
P*MT
-------
6.A Restoration Implementation
What are the steps that should be followed for successful implementation?
How are boundaries for the restoration defined?
How is adequate funding secured for the duration of the project?
What tools are useful for facilitating implementation?
Why and how are changes made in the restoration plan once implementation has begun?
How are implementation activities organized?
How are roles and responsibilities distributed among restoration participants?
How is a schedule developed for installation of the restoration measures?
What permits and regulations will be necessary before moving forward with
restoration measures?
6.B Restoration Monitoring, Evaluation, and Adaptive Management
What is the role of monitoring in stream corridor restoration?
When should monitoring begin ?
How is a monitoring plan tailored to the specific objectives of a restoration initiative?
Why and how is the success or failure of a restoration effort evaluated?
What are some important considerations in developing a monitoring plan to evaluate the
restoration effort?
-------
Implementing,
Monitoring,
Evaluating,
and Adapting
6.A Restoration Implementation
6.B Restoration Monitoring, Evaluation,
and Adaptive Management
The development of restoration goals
and objectives and the formulation
and selection of restoration alternatives
does not mark the end of the restoration
plan development process. Successful
stream corridor restoration requires care-
ful consideration of how the restoration
design will be implemented, monitored,
and evaluated. In addition, it requires a
commitment to long-term planning and
management that facilitates adaptation
and adjustment in light of changing eco-
logical, social, and economic factors.
This chapter focuses on the final stages of
restoration plan development. It presents
the basics of restoration implementation,
monitoring, evaluation, and management
within a planning context. Specifically, the
administrative and planning elements as-
sociated with these activities are discussed
in detail. This chapter is intended to set
the stage for the technical or "how to"
discussion of restoration implementation,
monitoring, maintenance, and manage-
ment presented in Chapter 9. The present
chapter is divided into two main sections.
Section 6.A: Restoration Implementation
The first section examines the basics of
restoration implementation. It includes a
discussion of all aspects relevant to carry-
ing out the design, including funding,
-------
incentives, division of responsibili-
ties, and the actual implementation
process.
Section 6.B: Restoration
Monitoring, Evaluation, and
Adaptive Management
Once the basic design is executed,
the monitoring, evaluation, and
adaptation process begins. This sec-
tion explores some of the basic
considerations that need to be ad-
dressed in examining and evaluat-
ing the success of the restoration
initiative. In addition, it emphasizes
the importance of making adjust-
ments to the restoration design
based on information received dur-
ing the monitoring and evaluation
process. Note especially that the
plan development process can be
reiterated if conditions in or affect-
ing the stream corridor change or if
perceptions or goals change due to
social, economic, or legal develop-
ments.
6.A Restoration Implementation
Implementation is a critical component
of the stream corridor restoration
process. It includes all the activities nec-
essary to execute the restoration design
and achieve restoration goals and objec-
tives. Although implementation is typi-
cally considered the "doing," not the
"planning," successful restoration im-
plementation demands a high level of
advance scheduling and foresight that
constitutes planning by any measure.
Securing Funding for
Restoration Implementation
An essential component of any stream
corridor restoration initiative is the
availability of funds to implement the
restoration design. As discussed in
Chapter 4, identifying potential funding
sources should be one of the first prior-
ities of the advisory group and decision
maker. By the time the restoration ini-
tiative reaches the implementation
stage, however, the initial identification
of sources should be translated into
tangible resource allocations. In other
words, all needed funding should be
secured so that restoration implementa-
tion can be initiated. It is important to
remember that financing might ulti-
mately come from several sources. All
benefactors, both public and private,
should be identified and appropriate
cost-sharing arrangements should be
developed.
An important element of securing fund-
ing for restoration is linking the avail-
able resources to the specific activities
that will be part of implementation.
Specifically, it should be the responsi-
bility of the restoration planners to cat-
egorize the various activities that will be
part of the restoration, determine how
much each activity will cost to imple-
ment, and determine how much fund-
ing is available for each activity. In
performing this analysis it should be
noted that funding need not be thought
of exclusively in terms of available
"cash." Often many of the activities that
are part of the restoration effort can be
completed with the work of the staff of
a participating agency or other organi-
zation.
6-2
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Securing Funding for Anacostia Restoration Initiatives
The Anacostia Watershed Restoration Committee annually seeks funding for many restoration initiatives. In
FY91, more than 50 projects were funded by over a dozen local, state, and federal agencies. Funding sources
are matched with appropriate watershed projects. In about half a dozen
cases, special funding came from federal agencies like the Corps of
Engineers, USDA, and EPA. The overwhelming majority of projects, howev-
er, involved a skillful coordination of existing sources of support from state
and local governmental programs combined with additional help from
nongovernmental organizations such as Trout Unlimited and from other
citizen volunteers. The signatory agencies (e.g., the District of Columbia,
Prince George's and Montgomery Counties, and the state of Maryland)
fund most of the storm water retrofit, monitoring, and demonstration
projects, as well as public participation activities.
A key element in maximizing resources from existing programs is the orga-
nization of special technical assistance teams for priority subwatersheds
(Figure 6.1). Subwatershed Action Plan (SWAP) coordinators carry out
public education and outreach efforts, and they also assist in comparing
the management needs of their subwatersheds with activities of local gov-
ernment. Because many of the problems in the Anacostia relate to urban
storm water runoff, many infrastructure projects can have a bearing on
restoration needs. When such infrastructure projects are identified, SWAP coor-
dinators try to coordinate with the project sponsor and involve the sponsor in
the Anacostia program. If possible, the SWAP coordinator attempts to inte-
grate the retrofit and management objectives of the program and the project.
Hickey
Run
Watts Branch
Figure 6.1: Anacostia Basin.
Nine priority subwatersheds
compose the Anacostia Basin.
Source: MWCOG 1997. Reprinted by
permission.
It is important to note that there might
be insufficient funding to carry out all
of the activities outlined in the stream
corridor restoration design. In this situ-
ation, planners should recognize that
this is, in fact, a common occurrence
and that restoration should proceed.
An effort should be made, however, to
prioritize restoration activities, execute
them as effectively and efficiently as
possible, and document success. Typi-
cally, if the restoration initiative is
demonstrated as producing positive re-
sults and benefits, additional funding
can be acquired.
Identifying Tools to Facilitate
Restoration Implementation
In addition to securing funding, it is
important to identify the various tools
and mechanisms available to facilitate
the implementation of the restoration
design. Tools available to the stream
corridor restoration practitioner include
a mix of both nonregulatory or incen-
tive-based mechanisms and regulatory
mechanisms. The Tools for Facilitating the
Implementation of Stream Corridor
Restoration Measures box contains a list
and description of some of these tools.
As discussed in Chapter 4, the use of in-
centives can be effective in obtaining
participation from private landowners
REVERSE
Review
Chapter 4's
conservation
easement
section.
Restoration Implementation
6-3
-------
Important Components
of Restoration
Implementation
Securing Funding for Restoration
Implementation
m Identifying Tools to Facilitate
Implementation
m Dividing Implementation
Responsibilities
m Installing Restoration Measures
in the corridor and in gaining their
support for the restoration initiative
(Figure 6.2). Incentive programs in-
volving cost shares, tax advantages, or
technical assistance can encourage pri-
vate landowners to implement restora-
tion measures on their property, even
if the results of these practices are not
directly beneficial to the owner.
In addition to incentives, regulatory ap-
proaches are an important option for
Figure 6.2: Landowner participation.
Restoration on private lands can be facilitated
by landowners.
stream corridor restoration. Regulatory
programs can be simple, direct, and
easy to enforce. They can be effectively
used to control land use and various
land use activities.
Deciding which tool, or combination of
tools, is most appropriate for the
restoration initiative is not an easy en-
deavor. The following is a list of some
important tips that should be kept in
mind when selecting among these tools
(USEPA 1995a).
Without targeted and effective educa-
tion programs, technical assistance
and cost sharing alone will not
ensure implementation.
Enforcement programs can also be
costly because of the necessary
inspections and personnel needed to
make them effective.
The most successful efforts appear to
use a mix of both regulatory and
incentive-based approaches. An effec-
tive combination might include vari-
able cost-share rates, market-based
incentives, and regulatory backup
coupled with support services (gov-
ernmental and private) to keep con-
trols maintained and properly
functioning.
Dividing Implementation
Responsibilities
With funding in place and restoration
tools and activities identified, the focus
should shift to dividing the responsibil-
ities of restoration implementation
among the participants. This process
involves identifying all the relevant
players, assigning responsibilities, and
securing commitments.
Identifying the Players
The identification of the individuals
and organizations that will be responsi-
ble for implementing the design is
6-4
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Tools for Facilitating the Implementation of Stream Corridor
Restoration Measures
Education
Programs that target the key audience involved with or affected by the
restoration initiative to elicit awareness and support. Programs can
include technical information as well as information on the benefits and
costs of selected measures.
Technical Assistance
Tax Advantages
Cost-share to Individuals
Cross-compliance Among
Existing Programs
Direct Purchase of Stream
Corridors or of Lands Causing
the Greatest Problems
One-to-one interaction between professionals and the interested citizen
or landowner. Includes provision of recommendations and technical assis-
tance about restoration measures specific to a stream corridor or reach.
Benefits that can be provided through state and local taxing authorities
or by a change in the federal taxing system that rewards those who
implement certain restoration measures.
Direct payment to individuals for installation of specific restoration mea-
sures. Most effective where the cost-share rate is high enough to elicit
widespread participation.
A type of quasi-regulatory incentive/disincentive that conditions benefits
received on meeting certain requirements or performing in a certain way.
Currently in effect through the 1985, 1990, and 1996 Farm Bills.
Direct purchase of special areas for preservation or community-owned
greenbelts in urban areas. Costs of direct purchase are usually high, but
the results can be very effective. Sometimes used to obtain access to
critical areas whose owners are unwilling to implement restoration
measures.
Nonregulatory Site Inspections
Peers
Periodic site visits by staff of local, state, or federal agencies can be a
powerful incentive for voluntary implementation of restoration measures.
Simple social acceptance by one's peers or members of the surrounding
community, which can provide the impetus for an individual landowner
to implement restoration measures. For example, if a community values
the use of certain agricultural best management practices (BMPs), pro-
ducers in those communities are more likely to install them.
Restoration Implementation
6-5
-------
Tools for Facilitating the Implementation of Stream Corridor
Restoration Measures (continued)
Direct Regulation of Land Use
and Production Activities
Easements
Regulatory programs that are simple, direct, and easy to enforce. Such
programs can regulate land uses in the corridor (through zoning ordi-
nances) or the kind and extent of activities permitted, or they can set per-
formance standards for a land activity (such as retention of the first inch
of runoff from urban property in the corridor).
Conservation easements on private property are excellent tools for imple-
menting parts of a stream corridor restoration plan (see more detailed
discussion in following box). Flowage easements may be a critical compo-
nent in order to design, construct, and maintain structures and flow
conditions.
Donations
In some instances, private landowners may be willing, or may be pro-
vided economic or tax incentives, to donate land to help implement a
restoration initiative.
Financing
Normally, a restoration initiative will require multiple sources of funds,
and no single funding source may be sufficient. Non-monetary
resources may also be instrumental in successfully implementing a
restoration initiative.
essential to successful stream corridor
restoration. Since the restoration part-
ners are identified early in the planning
process, at this point the focus should
be on "reviewing" the list of partici-
pants and identifying the ones who are
most interested in the implementation
phase. Although some new players
might emerge, most of the participants
interested in the implementation phase
will already have been involved in some
aspect of the restoration effort (Figure
6.4). Typically, partners will change
their participation as the process shifts
from "evaluating" to "doing."
The decision maker(s), with assistance
from the advisory group, should iden-
tify the key partners that will be actively
involved in the implementation
process.
Assigning Responsibilities
To ensure the effective allocation of re-
sponsibilities among the various partici-
pants, the decision maker(s) and
advisory group should rely on a special
interdisciplinary technical team. Specifi-
cally, the technical team should oversee
and manage the implementation
process as well as coordinate the work
of other participants, such as contrac-
tors and volunteers, involved with
restoration implementation. The fol-
lowing are some of the responsibilities
of the major participants involved in
the implementation process.
6-6
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Conservation Easements
Conservation easements are an effective stream
corridor management tool on private property
regardless of whether the stream reach supports
high biodiversity or the stream corridor would ben-
efit from active restoration in conjunction with a
modification of adjacent land use activities
(Figure 6.3). Through a conservation easement,
landowners receive financial compensation for giv-
ing up or modifying some of their development
rights while the easement holder acquires the right
to enforce restrictions on the use of the property.
Specific details of a conservation easement are
developed on a case-by-case basis. Only those
activities which may be considered incompatible
with stream corridor management objectives may
be restricted. The value of a conservation ease-
ment is typically estimated as the difference
between the values of the underlying land with
and without the restrictions imposed by the con-
servation easement. Government agencies or non-
profit organizations must compensate landowners
for the rights they are giving up, but not to exceed
more than the results are worth to society. The fair
market values of the land before and after an
easement is established are based on the "highest
and best" uses of the land with and without the
restrictions imposed by the easement. Once a con-
servation easement is established, it becomes part
of the title on the property, and any stipulations of
the conservation easement are retained when the
property is sold. Conservation easements may be
established indefinitely or for 25 to 30 years.
Conservation easements may be established with
federal agencies, such as the U.S. Fish and Wildlife
Service or the Natural Resources Conservation
Service, with state agencies, or through nonprofit
organizations like The Nature Conservancy or
Public Land Trusts. It is often beneficial for federal,
state, or local governments to establish conserva-
tion easements in partnership with nonprofit orga-
nizations. These organizations can assist public
agencies in acquiring and conveying easements
more efficiently since they are able to act quickly,
take advantage of tax incentives, and mobilize
local knowledge and support.
Conservation easements are beneficial to all parties
involved. The landowners benefit by receiving
financial compensation for giving up the rights to
certain land use activities, enhancing the quality of
the natural resources present on their property,
and, when applicable, eliminating problems associ-
ated with human use in difficult areas. The quality
of the land will also increase as a result of provid-
ing increased fish and wildlife habitat, improving
water quality by filtering and attenuating sedi-
ments and chemicals, reducing flooding, recharg-
ing ground water, and protecting or restoring bio-
logical diversity. Conservation easements are also
beneficial to public resource agencies because, in
addition to the public benefit of improved quality
of the stream corridor's natural resources, they
provide an opportunity for public agencies to influ-
ence resource use without incurring the political
costs of regulation or the full financial costs of
outright land acquisition.
Figure 6.3: Conservation easement.
Conservation easements are an effective tool
for protecting valuable areas of the stream
corridor.
Restoration Implementation
6-7
-------
REVERSE
Review
Chapter's
organizational
consideration
section.
Interdisciplinary Technical Team
As noted above, the interdisciplinary
technical team is responsible for over-
seeing and coordinating restoration
implementation and will assign imple-
mentation responsibilities. Before iden-
tifying roles, however, the technical
team should establish some organiza-
tional ground rules. Some Important Or-
ganizational Considerations for Successful
Teamwork reviews some of the impor-
tant logistical issues that need to be ad-
dressed by the team. Organizational
considerations are also addressed in
Chapter 4.
In addition to establishing ground
rules, the technical team should ap-
point a single project manager. This
person must be knowledgeable about
the structure, function, and condition
of the stream corridor; the various ele-
ments of the restoration design; and the
policies and missions of the various co-
Decision Maker
Responsible for organizing the advisory
group and for leading the stream
corridor restoration initiative. The
decision maker can be a single
organization or a group of individuals
or organizations that have formed a
partnership. Whatever thec^se ti^t
important that the '"'
restoration effort be
Technical Team
Analyzing condition
of stream corridor
structure and
functions.
Technical Team
Researching and
evaluating funding
options for the stream
corridor restoration
lit « 9JL9
Advisory Group
Provides consensus based
recommendations to the
decision maker based upon
information from the
technical teams and input
from all participants.
Technical Team
Analyzing social and
cultural issues and
concerns relevant to the
stream corridor
restorative initiative.
Technical Team
Analyzing economic
issues and concerns
relevant to the
stream corridor
restoration initiative.
Technical Team
Coordinating and
managing restoration
implementation
Volunteers
Contractors
Figure 6.4: Communication flow. This depicts a
possible scenario in which volunteers and con-
tractors may become actively involved.
operating agencies, citizen groups, and
local governments. When consensus-
based decisions are not possible due to
time limitations, the project manager
must be able to make quick and in-
formed decisions relevant to restoration
implementation.
Once the organizational issues have
been taken care of, the technical team
can begin to address its coordination
and management responsibilities. In
general, the technical team must grap-
ple with several major management is-
sues during the implementation
process. The following are some of the
major questions that are essential to
successful management:
How much time is required to imple-
ment the restoration?
Which tasks are critical to meeting
the schedule?
What resources are necessary to
complete the restoration?
Who will perform the various
restoration activities?
Is the implementation team ade-
quately staffed?
Are adequate lines of communica-
tion and responsibility established?
Are all competing and potentially
damaging interests and concerns
adequately represented, understood,
and addressed?
Volunteers
Volunteers can be very effective in as-
sisting with stream corridor restoration
(Figure 6.5). Numerous activities that
are part of the restoration implementa-
tion process are suitable for volunteer
labor. For example, soil bioengineering
and other uses of plants to stabilize
slopes are labor-intensive. Two crews of
at least two people each are needed for
all but the largest installationsone
crew at the harvest location and the
6-8
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Some Important Organizational Considerations for Successful Teamwork
Meeting
Mechanics
How often will the team meet?
Where?
What will the agenda include?
How do members get items on the agenda?
Who will take minutes?
How will minutes be distributed?
Who will facilitate the meetings?
Team Decision
Making
How will the team make decisions (vote, consensus, advise only)?
What decisions must be deferred to higher authorities?
Problem
Solving
How will problems be addressed?
How will disagreements be resolved?
What steps will be taken in the event of an impasse?
Communication
and Information
What additional information does the team need to function?
How will necessary information be shared among team members, and by whom?
Who handles public relations?
Leadership
Support
What is needed from supervisors and/or managers to ensure project success?
other at the implementation site. How-
ever, a high level of skill or experience
is often not required except for the crew
leader, and training can commonly
occur on the job. Restoration installa-
tions involving plant materials are
therefore particularly suitable for youth,
Job Corps, or volunteer forces.
It should be noted that the use of vol-
unteers is not without some cost.
Equipment, transportation, meals, in-
surance, and training might all be re-
quired, and each carries a real dollar
need that must be met by the project
budget or by a separate agency sponsor-
ing the volunteer effort. However, those
Figure 6.5: Volunteer team. Volunteers can
perform important functions during the
restoration implementation process.
Restoration Implementation
6-9
-------
costs are still but a fraction of what
would otherwise be needed for nonvol-
unteer forces.
Contractors
Contractors typically have responsibili-
ties in the implementation of the
restoration design. In fact, many
restoration efforts require contracting
due to the staff limitations of participat-
ing agencies, organizations, and
landowners.
Contractors can assist in performing
some of the tasks involved in imple-
menting restoration design. Specifically,
they can be hired to perform various
tasks such as channel modification, in-
stallation of instream structures, and
bank revegetation (Figure 6.6). All tasks
performed by the contractor should be
specified in the scope of the contract
and should be subject to frequent and
periodic inspection to ensure that they
Figure 6.6: Contractor team. Contractors can
assist in performing tasks that might be
involved in restoration such as installing bank
stabilization measures.
Source: Robin Sotir and Associates.
are completed within the proper specifi-
cations.
Although the contract will outline the
role the contractor is to perform, it
might be helpful for the technical team
(or a member of the technical team) to
meet with the contractor to establish a
clear understanding of the respective
roles and responsibilities. This prein-
stallation meeting might also be used
to formally determine the frequency
and mechanisms for reporting the
progress of any installation activities.
On the next page is a checklist of issues
that are helpful in determining some of
the roles and responsibilities associated
with using contractors to perform
restoration-related activities.
Securing Commitments
The final element of the division of re-
sponsibilities is securing commitments
from the organizations and individuals
that have agreed to assist in the imple-
mentation process. Two types of com-
mitments are particularly important to
ensuring the success of stream corridor
restoration implementation (USEPA
1995):
Commitments from public agencies,
private organizations, individuals,
and others who will fund and imple-
ment programs that involve restora-
tion activities.
Commitments from public agencies,
private organizations, individuals,
and others who will actually install
the restoration measures.
One tool that can be used to help se-
cure a commitment is a Memorandum
of Understanding (MOU). An MOU is
an agreement between two or more par-
ties that is placed in writing. Essentially,
by documenting what each party specif-
ically agrees to, defining ambiguous
concepts or terms, and outlining a con-
flict resolution process in the event of
6-10
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Some Issues That Should Be Considered in Addressing Contractor Roles
and Responsibilities
What constitutes successful completion of the contract obligations by the contractor?
m What is the planned order of work and necessary scheduling?
m Who is responsible for permitting?
m Where are utilities located and what are the related concerns?
m What is the relationship between the prime contractor and subcontractors? (In general, the chain of com-
munication should always pass through the prime contractor, and the prime contractor's representative is
always present on site. Normally, clients reserve the right to approve or reject individual subcontractors.)
m What records and reports will be needed to provide necessary documentation (forms, required job site
postings, etc.)?
m What arrangements are needed for traffic control?
m What specific environmental concerns are present on the site? Who has permit responsibility, both for
obtaining and for compliance?
misunderstandings, an MOU serves to
formalize commitments, avoid disap-
pointment, and minimize potential
conflict.
A second tool that can be effective is
public accountability. As emphasized
earlier, the restoration process should
be an "open process" that is accessible
to the interested public. Once written
commitments have been made and
announced, a series of periodic public
meetings can be scheduled for the pur-
pose of providing updates on the at-
tainment of the various restoration
activities being performed. In this way,
participants in the restoration effort can
be held accountable.
Installing Restoration
Measures
A final element of stream corridor
restoration implementation is the
initiation of management and/or
installation of restoration measures in
accordance with the restoration design
(Figure 6.7). If the plan involves con-
struction, implementation responsibili-
ties are often given to a private
contractor. As a result, the contractor is
required to perform a variety of restora-
tion implementation activities, which
can include large-scale actions like chan-
nel reconfiguration as well as small-scale
actions like bank revegetation.
Whatever the scale of the restoration ac-
tion, the process itself typically involves
several stages. These stages generally in-
clude site preparation, site clearing, site
construction, and site inspection. Each
stage must be carefully executed to en-
sure successful installation of restora-
tion measures. (See Chapter 9 for a
more detailed explanation of this
process.)
In addition to careful execution of the
installation process, it is important that
all actions be preceded by careful plan-
FAST
FORWARD
Preview
Chapter 9's
restoration
measures
section.
Restoration Implementation
6-11
-------
Review
Chapter 5's
permit section.
ning. Such preinstallation planning is
essential to achieve the desired restora-
tion objectives and to avoid adverse en-
vironmental, social, and economic
impacts that could result. The following
is a discussion of some of the major
steps that should be taken to ensure
successful implementation of restora-
tion-related installation actions.
Determining the Schedule
Scheduling is a very important and
highly developed component of imple-
mentation planning and management.
For large-scale installation actions,
scheduling is now almost always exe-
cuted with the assistance of a computer-
based software program. Even for small
actions, however, the principles of
scheduling are worth following.
Figure 6.7: Installation of erosion control fabric.
Installing measures can be considered a "mid-
point" in restoration and not the completion.
Preceding installation is the necessary planning,
with monitoring and adaptive management
subsequent to the installation.
Table 6.1:
Examples of per-
mit requirements
for restoration
activities.
Local/State
Permits Required
Varies thresholds and definitions
vary by state
Permits Required
Section 10, Rivers and Harbors Act
of 1849
Section 404, Letters of permission
Federal Clean
Water Act Nationwide 3
permits
13
26
27
Regional permits
Individual permits
Activities Covered
e.g., clearing/grading, sensitive/critical areas, water quality,
aquatic access
Activities Covered
Building of any structure in the channel or along the banks
of navigable waters of the U.S. that changes the course,
condition, location, or capacity
Minor or routine work with minimum impacts
Repair, rehabilitation, or replacement of structures destroyed
by storms, fire, or floods in past 2 years
Bank stabilization less than 500 feet in length solely for erosion
protection
Filling of up to 1 acre of a non-tidal wetland or less than 500
linear feet of non-tidal stream that is either isolated from other
surface waters or upstream of the point in a drainage
network where the average annual flow is less than 5cfs
Restoration of natural wetland hydrology, vegetation, and
function to altered and degraded non-tidal wetlands, and
restoration of natural functions of riparian areas on private
lands, provided a wetland restoration or creation agreement
has been developed
Small projects with insignificant environmental impacts
Proposed filling or excavation that causes severe impacts,
but for which no practical alternative exists; may require an
environmental assessment
Section 401, Federal Clean Water Act Water quality certification
Section 402, Federal Clean Water Act
National Pollutant Discharge
Elimination System (NPDES)
Endangered Species Act
Incidental Take Permit
Point source discharges, as well as nonpoint pollution
discharges
Otherwise lawful activities that may take listed species
Administered By
Local grading,
planning, or building
departments; various
state departments
Administered By
U.S. Army Corps
of Engineers
U.S. Army Corps
of Engineers
State agencies
State agencies
U.S. Fish and Wildlife
Service
6-12
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
For tasks that are part of the actual in-
stallation work, scheduling is most effi-
ciently done by the contractor actually
charged with doing the work. All sup-
porting activities, both before and dur-
ing installation, must be carefully
scheduled as well and should be the re-
sponsibility of the project manager.
Obtaining the Necessary Permits
Restoration installation actions con-
ducted in or in contact with streams,
wetlands, and other water bodies are
subject to various federal, state, and
local regulatory programs and require-
ments. At the federal level, a number of
these are aimed at protecting natural re-
sources values and the integrity of the
nation's water resources. As discussed in
Chapter 5, most of these require the is-
suance of permits by local, state, and
federal agencies.
If the action will be conducted or assis-
tance provided by a federal agency, the
agency is required to comply with fed-
eral legislation, including the National
Environmental Policy Act; sections 401,
402, and 404 of the Clean Water Act;
the Endangered Species Act; Section 10
of the Rivers and Harbors Act of 1899;
executive orders for floodplain manage-
ment and wetland protection; and pos-
sibly other federal mandates depending
on the areas that would be affected (see
Table 6.1).
For example, under the Endangered
Species Act, federal agencies must en-
sure that actions they take will not
jeopardize the continued existence of
listed threatened or endangered species
or destroy or adversely modify their
critical habitats (Figure 6.8). Where an
action would jeopardize a species, rea-
sonable and prudent alternatives must
be implemented to avoid jeopardy. In
addition, for federal agencies, an inci-
dental take statement is required in
Figure 6.8: Southwestern willow flycatcher.
Prior to initiating implementation activities,
permits may be needed to ensure the protec-
tion of certain species such as the
Southwestern willow flycatcher.
those instances where there will be a
"taking" of species associated with the
federal action. For non-federal activities
that might result in "taking" of a listed
species, an incidental take permit is
required.
Any work in floodplains delineated for
the National Flood Insurance Program
might also require participating com-
munities to adhere to local ordinances
and obtain special permits.
If the activity will affect lands such as
historic sites, archaeological sites and
remains, parklands, National Wildlife
Refuges, floodplains, or other federal
lands, meeting requirements under a
number of federal, state, or local laws
might be necessary. Familiarity with the
likely requirements associated with the
activities to be conducted and early
contact with permitting authorities will
help to minimize delays. Local grading,
planning, or building departments are
Restoration Implementation
6-13
-------
Using this diagram, determine where your activity will occur. The letters refer to the
permits listed below.
Permit Government Agency
A Montana Stream Protection Act (124) Montana Fish, Wildlife & Parks
B Storm Water Discharge General Permits .
C Streamside Management Zone Law
D Montana Floodplain and Floodway
Management Act
E Short-term Exemption from Montana's..
Surface Water Quality Standards (3A)
F Montana Natural Streambed and
Land Preservation Act (310)
G Montana Land-use License or
Easement on Navigable Waters
.. Department of Environmental Quality
. .Department of Natural Resources & Conservation
. .Department of Natural Resources & Conservation
.. Department of Environmental Quality
Montana Association of Conservation Districts and
Department of Natural Resources & Conservation
Department of Natural Resources & Conservation/
Special Uses
H Montana Water Use Act Department of Natural Resources & Conservation
I Federal Clean Water Act (Section 404) U.S. Army Corps of Engineers
J Federal Rivers and Harbors Act (Section 10).. U.S. Army Corps of Engineers
K Other laws that may apply various agencies
depending upon your location & activity
Figure 6.9: Example of permits necessary for
working in and around streams in Montana.
The number of permits required for an aquatic
restoration effort may appear daunting but
they are all necessary.
Source: MDEQ 1996. Reprinted by permission.
usually the best place to begin the per-
mit application process. They should
be approached as soon as a conceptual
outline of the project has been devel-
oped. At such a preapplication meet-
ing, the project manager should bring
such basic design information as the
following:
A site map or plan.
A simple description of the restora-
tion measures to be installed.
Property ownership of the site and
potential access route(s).
Preferred month and year of imple-
mentation.
Whether or not that local agency claims
jurisdiction over the particular activity,
its staff will normally be aware of state
and federal requirements that might be
applicable. Local permit requirements
vary from place to place and change pe-
riodically, so it is best to contact the ap-
propriate agency for the most current
information. In addition, different juris-
dictions handle the designation of sen-
sitive or critical areas differently. Work
that occurs in the vicinity of a stream or
wetland might or might not be subject
to state or local permit requirements
unique to aquatic environments. In ad-
dition, state and local agencies might
regulate other aspects of a project as
well.
The sheer number of permits required
for an aquatic restoration effort might
appear daunting, but much of the re-
quired information and many of the re-
medial measures are the same for all.
Figure 6.9 shows an example of how
Montana's permitting requirements
mesh with those at the federal level.
Holding Preinstallation
Conferences
Preinstallation conferences should be
conducted on site between the project
manager and supervisor, crew foreman,
and contractor(s) as appropriate. The
purpose is to establish a clear under-
standing of the respective roles and re-
sponsibilities, and to formally
determine the frequency and mecha-
nisms for reporting the progress of the
work. In a typical situation, the agency
reviews consultant work, provides guid-
ance in the interpretation of internal
agency documents or guidelines, and
takes a lead or at least supporting role
in acquiring permits and satisfying the
requirements imposed by regulatory
agencies. An additional conference with
any inspectors should be held with all
affected contractors and field supervi-
6-14
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
sors to avoid potential misunderstand-
ings. Volunteers and noncontractor per-
sonnel should also be involved if they
are critical to implementation.
At particularly sensitive sites, the need
to avoid installation-related damage
should be valued at least as highly as
the need to complete the planned im-
plementation actions as designed. An
on-site meeting, if appropriate to the
timing of installation and the seasonal-
ity of storms, can avoid many of the
emergency problems that might other-
wise be encountered in the future. At
a minimum, the project manager or
on-site superintendent and the local
inspector(s) for the permitting juris-
diction^) should attend. Other
people with relevant knowledge and
responsibility could also include the
grading contractor's superintendent,
the civil engineer or landscape architect
responsible for the erosion and sedi-
ment control plans, a soil scientist or
geologist, a biologist, and the plan
checker(s) from the permitting juris-
diction^) (Figure 6.10).
The meeting should ensure that all as-
pects of the plans are understood by the
field supervisors, that the key actions
and most sensitive areas of the site are
recognized, that the sequence and
schedule of implementing control mea-
sures are agreed upon, and that the
mechanism for emergency response is
clear. Any changes to the erosion and
sediment control plan should be noted
on the plan documents for future refer-
ence. Final copies of plans and permits
should be obtained, and particular at-
tention should be paid to changes that
might have been recorded on submitted
and approved plan copies, but not
transferred to archived or contractor
copies.
Involving Property Owners
If possible, the project manager should
contact and meet with neighbors af- <
fected by the work, including those
with site ownership, those granting ac-
cess and other easements, and others
nearby who might endure potential
noise or dust impacts.
Securing Site Access
Obtaining right of entry onto private
property can be a problematic and
time-consuming part of restoration
(Figure 6.11). Several types of access
agreements with differing rights and
obligations are available:
Right of entry is the right to pass over
the property for a specific purpose
for a limited period of time. In many
cases, if landowners are involved
from the beginning, they will be
aware of the need to enter private
property. Various types of easements
can accomplish this goal.
-
Figure 6.10: On-site meeting. Many problems
that might otherwise be encountered can
be avoided by appropriately timed on-site
meetings.
Restoration Implementation
6-15
-------
Implementation easement defines the
location, time period, and purpose
for which the property can be used
during implementation.
Access easement provides for perma-
nent access across and on private
property for maintenance and moni-
toring of a project. The geographic
limits and allowable activities are
specified.
Drainage easement allows for the
implementation and permanent
maintenance of a drainage facility at
a particular site. Usually, the property
owner has free use of the property
for any nonconflicting activities.
Fee acquisition is the outright pur-
chase of the property. It is the most
secure, but most expensive, alterna-
tive. Normally, it is unnecessary
unless the project is so extensive that
all other potential activities on the
property will be precluded.
In many cases little or no money may
be exchanged in return for the ease-
ment because the landowner receives
substantial property improvements,
such as stabilized streambanks, im-
proved appearance, better fisheries, and
permanent stream access and stream
crossings. In some instances, however,
the proposed implementation is in di-
rect conflict with existing or planned
uses, and the purchase of an easement
must be anticipated.
Locating Existing Utilities
Since most restoration efforts have a
lower possibility of encountering utili-
ties than other earthwork activities, spe-
cial measures might not be necessary. If
utilities are present, however, certain
principles should be remembered (King
1987).
First, field location and highly visible
markings are mandatory; utility atlases
are notoriously incomplete or inaccu-
Figure 6.11: Site access. In certain areas, access agreements, such as a right of entry or implemen-
tation easement, might have to be obtained to install restoration measures.
6-16
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
rate. Utilities have a particular size and
shape, not just a location, which might
affect the nature or extent of adjacent
implementation. They also require con-
tinuous support by the adjacent soil or
temporary restraining structures. Rights-
of-way might also create constraints
during and after implementation. Even
though all potential conflicts between
utilities and the proposed implementa-
tion should be resolved during imple-
mentation planning, field discovery of
unanticipated problems occurs fre-
quently. Resolution comes only with
the active involvement of the utility
companies themselves, and the project
manager should not hesitate to bring
them on site as soon as a conflict is
recognized.
Confirming Sources and Ensuring
Material Standards
First, the project manager must deter-
mine the final sources of any required
fill dirt and then arrange a pickup
and/or delivery schedule. The project
manager should also confirm the
sources of nursery and donor sites for
plant materials. Note, however, that de-
laying the initial identification of these
sources until the time of site prepara-
tion almost guarantees that the project
will suffer unexpected delays. In addi-
tion, it is important to double check
with suppliers that all materials sched-
uled for delivery or pickup will meet
the specified requirements. Early atten-
tion to this detail will avoid delays im-
posed by the rejection of substandard
materials.
Characteristics of Successful
Implementation
As was discussed earlier, successful
restoration requires the efficient and ef-
fective execution of several core imple-
mentation activities, such as installing
restoration measures, assigning respon-
Characteristics of Successful
Implementation
Central responsibility in one person
m Thorough understanding of planning and design
documents
m Familiarity with the site and its biological and physical
framework
m Knowledge of laws and regulations
m Understanding of environmental control plans
m Communication among all parties involved in the
project action
sibilities, identifying incentives, and se-
curing funding. The Winooski River
Case Study is a good example. Cutting
across these core activities, however, are
a few key concepts that can be consid-
ered characteristics of successful restora-
tion implementation efforts.
Central Responsibility in
One Person
Most restoration efforts are a product of
teamwork, involving specialists from
such disparate disciplines as biology,
geology, engineering, landscape archi-
tecture, and others. Yet the value of a
single identifiable person with final re-
sponsibility cannot be overemphasized.
This project manager ignores the rec-
ommendations and concerns of the
project team only at his or her peril.
Rapid decisions, particularly during im-
plementation, must nonetheless often
be made. Rarely are financial resources
available to keep all members of the de-
sign team on site during implementa-
tion, and even if some members are
present, the time needed to achieve a
consensus is simply not available.
Restoration Implementation
6-17
-------
OVSESUIDY Successful Implementation: The
£*7 Winooski River Watershed Project,
Vermont
In the late 1930s, an extensive watershed
restoration effort known as "Project Vermont"
was implemented in the Lower Winooski River
Watershed, Chittenden County, Vermont. The pro-
ject encompassed the lower 111 square miles
(including 340 farms) of the 1,076-square-mile
Winooski River Watershed.
The Winooski River Watershed sustained severe
damage from major floods during the 1920s and
1930s. In addition, overgrazing, poor soil conser-
vation practices on cropland areas, encroachment
to the streambanks, and forest clear-cutting also
led to excessive erosion (Figure 6.12). Annual ice-
flows and jams during snowmelt runoff further
exacerbated riverbank erosion. Throughout the
watershed, both water and wind erosion were
prevalent. In addition to problems in the low-lying
areas, there were many environmental problems to
address on the uplands. The soil organic matter
was depleted in some areas, cropland had low
productivity, pastures were frequently overgrazed,
cover for wildlife was sparse, and forest areas had
been clear-cut in many areas. In some cases, this
newly cleared land was subject to grazing, which
created additional problems.
Figure 6.12: Brushmattress and plantings after spring
runoff in March 1938. Note pole jetties. Brushmatting
involves applying a layer of brush fastened down with
live stakes and wire.
The Soil Conservation Service (SCS) joined with the
University of Vermont (UVM) and local landowners
to formulate a comprehensive, low-input approach
to restoring and protecting the watershed. One
hundred eighty-nine farmers participated in devel-
oping conservation plans for their farms, which
covered approximatey 57 square miles. Other
cooperators applied practices to another 38-
square-mile area. Their approach relied heavily on
plantings or a combination of plantings and
mechanical techniques to overcome losses of both
land and vegetated buffer along the river corridor,
and in the uplands to make agricultural land sus-
tainable and to restore deteriorating forest/and.
The measures, many of which were experimental
at the time, were installed from 1938 to 1941
primarily by landowners. Landowners provided
extensive labor and, occasionally, heavy equipment
for earthmoving and transportation and placement
of materials too heavy for laborers. SCS provided
interdisciplinary (e.g., agronomy, biology, forestry,
soil conservation, soil science, and engineering)
technical assistance in the planning, design, and
installation. UVM provided extensive educational
services for marketing and operation and mainte-
nance.
In the stream corridor, a variety of measures were
implemented along 17 percent of the 33 river
miles to control bank losses, restore buffers, and
heal overbank floodflow channels. They included
the following:
m Livestock Exclusion: Heavy-use areas were fenced
back 15 feet from the top of the bank on
straight reaches, 200 feet or wider on the out-
sides of curves, and 200 feet wide in flood over-
flow entrance and exit sections.
m Plantings and Soil Bioengineering Bank
Stabilization: Where the main current was not
directed toward the treatment, streambanks
were sloped back and planted with more than
6-18
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
600,000 cuttings and 70,000 plants, primarily
willow. Brushmattresses, which involved apply-
ing a layer of brush fastened down with live
stakes and wire, were used to protect the bank
until plantings could be made and established.
Where streamf/ow was directed toward the
bank, rock riprap was embedded at the toe up
to 2 or more feet above the normal water line.
Other toe protection techniques, such as pile
jetties, were used.
m Structures: In reaches where nearshore water
was deep (up to 14 feet) and bank voiding was
occurring, whole tree deflectors were used to
trap sediment and rebuild the voided section.
Trees with butt diameters of 2 to 3 feet were
placed longitudinally along the riverbank with
branches intact and with butts and tops slightly
overlapped. The butts were cabled to wooden
piles driven 8 to 10 feet into the bank. The
slope above the normal waterline was brush-
matted and planted.
Log pile check dams were constructed at the
entrances of flood overflow channels and filled
with one-person-size rocks for ballast. These
served as barriers to overbank flow along chan-
nels sculpted by previous floods. They were
installed in conjunction with extensive buffer
plantings, and in some cases, whole tree barri-
cades, that were laced down parallel to the
river along the top of the denuded bank.
m At overbank locations where flow threatened
buffer plantings, log cribs were inset parallel to
the bank and filled with rock. Various tree
species were planted as a 200-foot or wider
buffer behind the cribs. The cribs provided pro-
tection needed until the trees became well
established.
In the watershed, the conservation plans provided
for comprehensive management for sustainable
farming, grazing, forestry, and wildlife. The crop-
land practices included contour strips, contour
tillage, cover crops, crop and pasture rotation,
grass and legume plantings, diversions, grassed
waterways, log culvert crossings, contour furrows
in pastures, livestock fencing, planting of
hedgerows, field border plantings, reforestation,
and sustainable forest practices.
Figure 6.13: Same site (Figure 6.12) in April 1995. Note
remnants of old jetties and heavy bank cover. Restoration
measures are continuing to function well, more than 55
years after installation.
Wildlife habitat improvement practices provided
connectivity among the cropland, pasture, and
forest areas; hedgerow plantings as travelways,
food sources, and cover; livestock exclusion areas
to encourage understory herbaceous growth for
cover and food sources; snags for small mammals
and birds; and slash pile shelters as cover for rab-
bits and grouse.
One reason for this historic project's usefulness to
modern environmental managers is the extensive
documentation, including photos, maps, and
detailed observations and records, available for
many of the sites. Complete aerial photography is
available from before, during, and after imple-
mentation. More than 600 photos provide a
chronology of the measures, and three successive
studies (Edminster and Atkinson 1949, Kasvinsky
1968, Ryan and Short 1995) document the per-
formance of the project.
The restoration measures implemented are con-
tinuing to function well today, more than 55
years after installation. Tree plantings along the
corridor have matured to diameters as great as
45 inches and heights exceeding 100 feet (Figure
6.13). The wooded river corridor averages 50 feet
wider than it did in the 1930s. Some of the mea-
sures have failed, however, including all plantings
without toe protection. Lack of maintenance and
long-term follow-up also resulted in the failure of
restoration efforts at several sites.
Restoration Implementation
6-19
-------
CASESUIDY The Winooski River Watershed Project
^*^JJJ9 (continued)
A
/though the Winooski project was experimental in the 1930s, many of its elements were highly
successful:
Recognition of the importance of landscape relationships and an emphasis on comprehensive
treatment of the entire watershed rather than isolated, individual problem areas.
Using an interdisciplinary technical team for planning and implementation.
Strong landowner participation.
Empowerment of landowners to carry out the restoration measures using low-cost approaches
(often using materials from the farm).
Fostering the use of experimental methods that are now recognized as viable biotechnical
approaches.
The success of restoration efforts de-
pends more on having a competent
project manager than on any other fac-
tor. The ideal project manager should
be skilled in leadership, scheduling,
budgeting, technical issues, human rela-
tionships, communicating, negotiating,
and customer relations. Most will find
this a daunting list of attributes, but an
honest evaluation of a manager's short-
comings before restoration is under way
might permit a complementary support
team to assist the one who most com-
monly guides restoration to comple-
tion.
Thorough Understanding of
Planning and Design Materials
Orchestrating the implementation of all
but the simplest restoration efforts re-
quires the integration of labor, equip-
ment, and supplies, all within a context
determined by requirements of both
the natural system and the legal system.
Designs must be adequate and based
on a foundation of sound physical and
biological principles, tempered with the
experience of past efforts, both success-
ful and unsuccessful. Schedules must
anticipate the duration of specific im-
plementation tasks, the lead time neces-
sary to prepare for those tasks, and the
consequences of inevitable delays. A
manager who has little familiarity with
the planning and design effort can nei-
ther execute the implementation plans
efficiently nor adjust those plans in the
face of unanticipated conditions. A cer-
tain amount of flexibility is key. Often
specific techniques are tied to specific
building material, for example. Adjust-
ments are often made according to
what is available.
Familiarity With the Reach
Existing site conditions are seldom as
they appear on a set of engineering
plans. Variability in landform and vege-
tation, surface water and ground water
flow, and changing site conditions dur-
ing the interval between initial design
and final implementation are all in-
evitable. There is no substitute for fa-
miliarity with the site that extends
beyond what is shown on the plans, so
that implementation-period "surprises"
are kept to a minimum (Figure 6.14).
Similarly, when such surprises do occur,
6-20
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Figure 6.14: Workers installing a silt fence.
Familiarity with on-site conditions is critical to
successful implementation of restoration
measures.
a sound response must be based on the
project manager's understanding of
both the restoration goals and the likely
behavior of the natural system.
Knowledge of Laws and
Regulations
Site work in and around aquatic fea-
tures is one of the most heavily regu-
lated types of implementation in the
United States (Figure 6.15). Restrictions
on equipment use, season of the year,
distance from the water's edge, and
types of material are common in regu-
lations from the local to the federal
level. Not appreciating those regula-
tions can easily delay implementation
by a year or more, particularly if narrow
seasonal windows are missed. The cost
of a project can also multiply if re-
quired measures or mitigation are
discovered late in the design or imple-
mentation process.
Understanding of Environmental
Control Plans
A project in which a designed restora-
tion measure is installed but the ecolog-
ical structure and function of an area are
destroyed is no success. The designer
must create a workable plan for mini-
mizing environmental degradation, but
the best of plans can fail in the field
through careless implementation.
Communication Among All
Parties Involved in the Action
Despite the emphasis here on a single
responsible project manager, the suc-
cess of a project depends on regular,
frequent, and open communication
among all parties involved in imple-
mentationmanager, technical sup-
port people, contractor, crews, inspec-
tors, and decision maker(s). No
restoration effort proceeds exactly ac-
cording to plans, and not every contin-
gency can be predicted ahead of time.
But well-established lines of communi-
cation can overcome most complica-
tions that arise.
Figure 6.15: Instream construction activity. Site
work in and around aquatic features is one of
the most heavily regulated types of activity in
the United States and should not be attempted
without a sound knowledge of the relevant
laws and regulations.
Restoration Implementation
6-21
-------
6.B Restoration Monitoring, Evaluation, and
Adaptive Management
Preview
Chapter 9's
restoration
monitoring
management
section.
The restoration effort is not considered
complete once the design has been im-
plemented. Monitoring, evaluation, and
adaptive management are essential
components that must be undertaken
to ensure the success of stream corridor
restoration. Each is carried out at a dif-
ferent level depending on the size and
scope of the design.
Monitoring includes both pre- and
post-restoration monitoring, as well as
monitoring during actual implementa-
tion. All are essential to determining
the success of the restoration design
and require a complete picture or un-
derstanding of the structure and func-
tions of the stream corridor. Monitoring
provides needed information, docu-
ments chronological and other aspects
of restoration succession, and provides
lessons learned to be used in similar fu-
ture efforts (Landin 1995).
Directly linked to monitoring are restor-
ation evaluation and adaptive manage-
ment. Using the information obtained
from the monitoring process, the restor-
ation effort should be evaluated to en-
sure it is functioning as planned and
achieving the restoration goals and
objectives. Even with the best plans,
designs, and implementation, the eval-
uation will often result in the identifica-
tion of some unforeseen problems and
require midcourse correction either
during or shortly following implemen-
tation. Most restoration efforts will re-
quire some level of oversight and
on-site adaptive management.
This section examines some of the ba-
sics of restoration monitoring, evalua-
tion, and adaptive management. A more
detailed discussion on the technical
aspects of restoration monitoring
management is provided in Chapter 9
of this document.
Monitoring as Part of
Stream Corridor Restoration
Initiative
Restoration monitoring should be
guided by predetermined criteria and
checklists and allow for the recording of
results in regular monitoring reports. The
technical analyses in a monitoring re-
port should reflect restoration objectives
and should identify and discuss options
to address deficiencies. For example, the
report might include data summaries
that indicate that forest understory con-
ditions are not as structurally complex
as expected in a particular management
unit, that this finding has negative con-
sequences for certain wildlife species,
and that a program of canopy tree thin-
ning is recommended to rectify the
problem. The recommendation should
be accompanied by an estimate of costs
associated with the proposed action, a
proposed schedule, and identification of
possible conflicts with other restoration
objectives.
Restoration Monitoring,
Evaluation, and Adaptive
Management
Restoration Monitoring
Progress Toward Objectives
Regional Resource Priorities and Trends
Watershed Activities
Restoration Evaluation
m Reasons to Evaluate Restoration Efforts
mA Conceptual Framework for Evaluation
6-22
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Monitoring plans should be conceived
during the planning phase when the
goals and performance criteria are devel-
oped for the restoration effort. Baseline
studies required to provide more infor-
mation on the site, to develop restora-
tion goals, and to refine the monitoring
plan often are conducted during the
planning phase and can be considered
the initial phase of the monitoring
plan. Baseline information can form a
very useful data set on prerestoration
conditions against which performance
of the system can be evaluated.
Monitoring during the implementation
phase is done primarily to ensure that
the restoration plans are correctly car-
ried out and that the natural habitats
surrounding the site are not unduly
damaged.
Actual performance monitoring of the
completed plan is done later in the as-
sessment phase (Figure 6.16). Manage-
ment of the system includes both
management of the monitoring plan
and application of the results to make
midcourse corrections.
Finally, results are disseminated to in-
form interested parties of the progress
of the system toward the intended
goals.
ioals of a Restoration
Monitoring Plan
/Assess the performance of the
restoration initiative relative to
the project goals.
Provide information that can be
used to improve the performance
of the restoration actions.
Provide information about the
restoration initiative in general.
Components of a Monitoring
Plan
Based on a thorough review of freshwa-
ter monitoring plans, some of which
had been in place for over 30 years, the
National Research Council (NRG) rec-
ommended the following factors to
ensure a sound monitoring plan (NRC
1990):
Clear, meaningful monitoring plan
goals and objectives that provide the
basis for scientific investigation.
Appropriate allocation of resources
for data collection, management,
synthesis, interpretation, and
analysis.
Quality assurance procedures and
peer review.
Supportive research beyond the pri-
mary objectives of the plan.
Flexible plans that allow modifica-
tions where changes in conditions or
new information suggests the need.
Useful and accessible monitoring
information available to all interest-
ed parties.
The box, Developing a Monitoring Plan,
shows the monitoring steps throughout
the planning and implementation of a
restoration. Each step is discussed in
this chapter.
Figure 6.16:
Monitoring of re-
vegetation efforts.
Monitoring the results
of revegetation
efforts is a critical part
of restoring riparian
zones along highly
eroded channels.
Restoration Monitoring, Evaluation, and Adaptive Management
6-23
-------
When to Develop the
Monitoring Plan
The monitoring plan should be devel-
oped in conjunction with planning for
the restoration. Once the goals and ob-
jectives have been established in the
planning phase, the condition of the
system must be considered.
Baseline monitoring enables planners to
identify goals and objectives and pro-
vides a basis for assessing the perfor-
mance of the completed restoration.
Monitoring therefore begins with the de-
termination of baseline conditions and
continues through the planning and im-
plementation of the restoration plan.
Developing a Monitoring Plan
Step 1: Define the Restoration
Vision, Goals, and Objectives
The goals set for the restoration drive
the monitoring plan design. Above all,
it is important to do the following:
Make goals as simple and unambigu-
ous as possible.
Relate goals directly to the vision for
the restoration.
Set goals that can be measured or
assessed in the plan.
Developing Performance
Criteria Involves:
Linking criteria to restoration goals.
m Linking criteria to the actual measurement
parameters.
m Specifying the bounds or limit values for the
criteria.
Step 2: Develop the Conceptual
Model
A conceptual model is a useful tool for
developing linkages between planned
goals and parameters that can be used
to assess performance. In fact, a concep-
tual model is a useful tool throughout
the planning process. The model forces
persons planning the restoration to
identify direct and indirect connections
among the physical, chemical, and bio-
logical components of the ecosystem, as
well as the principal components on
which to focus restoration and moni-
toring efforts.
Baseline studies might be necessary to
meet the following needs:
To define existing conditions without
any actions.
To identify actions required to restore
the system to desired functions and
values.
To help design the restoration
actions.
To help design the monitoring plan.
Step 3: Choose Performance
Criteria
Link Performance to Goals
A link between the performance of the
system and the planned goals is critical.
If the goals are stated in a clear manner
and can be reworded as a set of testable
hypotheses, performance criteria can be
developed. Performance criteria are stan-
dards by which to evaluate measurable
or otherwise observable aspects of the
restored system and thereby indicate
the progress of the system toward meet-
ing the planned goals. The closer the tie
between goals and performance criteria,
the better the ability to judge the suc-
cess of the restoration efforts.
6-24
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Developing a Monitoring Plan
A. Planning
Step 7: Define the restoration, vision, goals, and
objectives
Step 2: Develop the conceptual model
Step 3: Choose performance criteria
Link performance to goals
Develop the criteria
Identify reference sites
Step 4: Choose monitoring parameters and
methods
Choose efficient monitoring
parameters
Review watershed activities
Choose methods for sampling design,
sampling, and sample handling/
processing
Conduct sociological surveys
Rely on instream organisms for
evidence of project success
Minimize the necessary measurements
of performance
Incorporate supplemental parameters
Step 5: Estimate cost
Cost for developing the monitoring
plan itself
Quality assurance
Data management
Field sampling program
Laboratory sample analysis
Data analysis and interpretation
Report preparation
Presentation of results
Step 6: Categorize the types of data
Step 7: Determine the level of effort and
duration of monitoring
Incorporate landscape ecology
Determine timing, frequency, and
duration of sampling
Develop statistical framework
Choose the sampling level
B. Implementing and Managing
Manager must have a vision for the
life of the monitoring plan
Roles and responsibilities must be
clearly defined
Enact quality assurance procedures
Interpret the results
Manage the data
Provide for contracts
C. Responding to the Monitoring Results
No action
Maintenance
Adding, abandoning, or
decommissioning plan elements
Modification of project goals
Adaptive management
Documentation and reporting
Dissemination of results
Restoration Monitoring, Evaluation, and Adaptive Management
6-25
-------
Primary Functions of Reference Sites
Can be used as models for developing restoration
actions for a site.
Provide a target to judge success or failure.
Provide a control system by which environmental
effects, unrelated to the restoration action, can be
assessed.
Develop the Criteria
The primary reason for implementing
the monitoring plan must be kept in
mind: to assess progress and to indicate
the steps required to fix a system or a
component of the system that is not
successful.
Criteria are usually developed through
an iterative process that involves listing
measures of performance relative to
goals and refining them to arrive at the
most efficient and relevant set of criteria.
Identify Reference Sites
A reference site or sites should be moni-
tored along with the restored site. Al-
though pre- and post-implementation
comparisons of the system are useful in
documenting effects, the level of success
can be judged only relative to reference
systems.
Step 4: Choose Monitoring
Parameters and Methods
Monitoring should include an overall
assessment of the condition and devel-
opment of the stream corridor relative
to projected trends or "target" condi-
tions. In some cases, this assessment
may involve technical analyses of
stream flow data, channel and bank
condition, bedload measurements, and
comparisons of periodic aerial photog-
raphy to determine whether stream mi-
gration and debris storage and transport
are within the range of equilibrium
conditions. Monitoring may also in-
clude forest inventories, range condi-
tion assessments, evaluations of fish
and wildlife habitat or populations, and
measurements of fire fuel loading. In
small rural or urban "greenbelt" pro-
jects, more general qualitative character-
ization of corridor integrity and quality
might be sufficient.
Numerous monitoring programs and
techniques have been developed for
particular types of resources, different
regions, and specific management ques-
tions. For example, general stream sur-
vey techniques are described by
Harrelson et al. (1994), while a re-
gional programmatic approach for
monitoring streams in the context of
forest management practices in the
Northwest is described in Schuett-
Hames et al. (1993). Similarly, moni-
toring of fish and wildlife habitat
quality and availability can be ap-
proached from various avenues, ranging
from direct sampling of animal popula-
tions to application of the habitat eval-
uation procedures developed and used
by the U.S. Fish and Wildlife Service
(1980a). Techniques specific to riparian
zone monitoring are given by Platts et
al. (1987).
Basic Questions to Ask When
Selecting Methods for
Monitoring
Does the method efficiently provide accu-
rate data?
Does the method provide reasonable and
replicable data?
Is the method feasible within time and cost
constraints?
6-26
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Choose Efficient Monitoring
Parameters
There are two critical steps in choosing
efficient monitoring parameters. The
first is to identify parameters to moni-
tor. A scientifically based, relatively eas-
ily measured set of parameters that
provide direct feedback on success or
failure of restoration actions are identi-
fied. The NRC (1992) has recom-
mended that at least three parameters
should be selected and that they in-
clude physical, hydrological, and eco-
logical measures. The second step is to
select regional and system-specific para-
meters. Criteria development must be
based on a thorough knowledge of the
system under consideration.
Those responsible for resources in the
stream corridor must be aware of
changing watershed and regional re-
source priorities. The appropriate place
to consider the implications of regional
needs is in the context of periodic
reevaluation of restoration objectives,
which is a function of the monitoring
process. Therefore, an annual monitor-
ing report should include recognition
of ongoing or proposed initiatives (e.g.,
changes in regulations, emphasis on
restoration of specific fish populations,
endangered species listings) that might
influence priorities in the restored corri-
dor. Awareness of larger regional pro-
grams may produce opportunities to
secure funding to support management
of the corridor.
Review Watershed Activities
The condition of the watershed controls
the potential to restore and maintain
ecological functions in the stream corri-
dor. As discussed in Chapter 3, changes
in land use and/or hydrology can pro-
foundly alter basic stream interactions
with the floodplain, inputs of sediment
and nutrients to the system, and fish
and wildlife habitat quality. Therefore,
it is important that stream corridor
monitoring include periodic review of
watershed cover and land use, including
proposed changes (Figure 6.17).
Patterns of water movement through
and within the stream corridor are basic
considerations in developing objectives,
design features, and management pro-
grams. Proposals to increase impervious
surfaces, develop storm water manage-
ment systems, or construct flood protec-
tion projects that reduce floodplain
storage potential and increase surface
and ground water consumption are all
of legitimate concern to the integrity of
the stream corridor. Stream corridor
managers should be aware of such pro-
posals and provide relevant input to the
planning process. As changes are imple-
mented, their probable influence on the
corridor should be considered in peri-
odic reevaluation of objectives and
maintenance and management plans.
In rural settings, the corridor managers
should be alert to land use changes in
agricultural areas (Figure 6.18). Con-
versions between crop and pasture
lands might require verification that
fencing and drainage practices are con-
sistent with agreed-upon BMPs or rene-
gotiation of those agreements. Simi-
larly, in wildland areas, major water-
shed management actions (timber har-
Figure 6.17: Urban
sprawl.
Understanding
changes in watershed
land uses, such as
increased urbaniza-
tion, is an important
aspect of restoration
monitoring.
Source: C. Zabawa.
REVERSE
Review
Chapter 3's
land use and
hydrology
Sections.
Restoration Monitoring, Evaluation, and Adaptive Management
6-27
-------
Figure 6.18:
Confinement farm.
Practitioners moni-
toring stream corri-
dor restoration in
rural areas should be
aware of changes in
agricultural land use.
vests, prescribed burn programs) should
be evaluated to ensure that stream cor-
ridors are adequately considered.
Increasing development and urbaniza-
tion may reduce the ability of the
stream corridor to support a wide vari-
ety of fish and wildlife species and, at
the same time, generate additional pres-
sure for recreational uses. Awareness of
development and population growth
trends will allow a rational, rather than
reactive, adjustment of corridor man-
agement and restoration objectives. Pro-
posals for specific implementation
activities, such as roads, bridges, or
storm water detention facilities, within
or near the stream corridor should be
scrutinized so that concerns can be con-
sidered before authorization of the
implementation.
Choose Methods for Sampling Design,
Sampling, and Sample Handling and
Processing
Parameters that might be included in a
restoration monitoring plan are well es-
tablished in the scientific literature. Any
methods used for sampling a particular
parameter should have a documented
protocol (e.g., Loeb and Spacie 1994).
Conduct Sociological Surveys
Scientifically designed surveys can be
used to determine changes in social
attitudes, values, and perceptions from
prerestoration planning through imple-
mentation phases. Such surveys may
complement physical, chemical, and
biological parameters that are normally
considered in a monitoring plan. Socio-
logical surveys can reveal important
shifts in the ways a community per-
ceives the success of a restoration effort.
Rely on Instream Organisms for
Evidence of Project Success
The restoration evaluation should usu-
ally focus on aquatic organisms and in-
stream conditions as the "judge and
jury" for evaluating restoration success.
Instream physical, chemical, and bio-
logical conditions integrate the other
factors within the stream corridor. In-
stream biota, however, have shown sen-
sitivity to complex problems not as well
detected by chemical or physical indica-
tors alone in state water quality moni-
toring programs. For instance, in
comparing chemical and biological cri-
teria, the state of Ohio found that bio-
logical criteria detected an impairment
in 49.8 percent of the situations where
no impairment was evident with chemi-
cal criteria alone. Agreement between
chemical and biological criteria was evi-
dent in 47.3 percent of the cases, while
chemical criteria detected an impair-
ment in only 2.8 percent of the cases
where biological criteria indicated at-
tainment (Ohio EPA 1990). As a result,
Ohio's Surface Water Monitoring and
Assessment Program has recognized
that biological criteria must play a key
role in defining water quality standards
and in evaluating and monitoring stan-
dards attainment if the goal to restore
and maintain the physical, chemical,
and biological integrity of Ohio's waters
is to be met.
6-28
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Minimize the Necessary
Measurements of Performance
A holistic perspective is needed when
monitoring restoration performance.
Still, monitoring should focus narrowly
on the fewest possible measurements or
indicators that most efficiently demon-
strate the overall condition of the
stream corridor system and the success
of the restoration effort. Costs and the
ability to develop statistically sound
data may quickly get out of hand unless
the evaluation measures chosen are nar-
rowly focused, are limited in number,
and incorporate existing data and work
wherever appropriate.
Existing data from state and federal
agencies, community monitoring pro-
grams, educational institutions, research
projects, and sportsmen's and other
groups should be considered when
planning for restoration evaluation. For
example, turbidity data are generally
more common than sediment data. If
one of the objectives of a restoration ef-
fort is to reduce sediment concentra-
tions, turbidity may provide a suitable
surrogate measurement of sediment at
little or no expense to restoration plan-
ners. Table 6.2 provides some other ex-
amples of restoration objectives linked
to specific performance evaluation tools
and measures.
Incorporate Supplemental Parameters
Although the focus of the monitoring
plan is on parameters that relate di-
rectly to assessment of performance,
data on other parameters are often use-
ful and may add considerably to inter-
pretation of the results. For example,
stream flow should be monitored if
water temperature is a concern.
Step 5; Estimate Cost
Various project components must be
considered when developing a cost esti-
mate. These cost components include:
General
Objectives
Channel
capacity
and stability
Improve
aquatic
habitat
Improve
riparian
habitat
Improve
water
quality
Recreation
and
community
involvement
Potential Evaluation Tools
and Criteria
Channel cross sections
Flood stage surveys
Width-to-depth ratio
Rates of bank or bed erosion
Longitudinal profile
Aerial photography interpretation
Water depths
Water velocities
Percent overhang, cover, shading
Pool/riffle composition
Stream temperature
Bed material composition
Population assessments for fish,
invertebrates, macrophytes
Percent vegetative cover
Species density
Size distribution
Age class distribution
Plantings survival
Reproductive vigor
Bird and wildlife use
Aerial photography
Temperature
PH
Dissolved oxygen
Conductivity
Nitrogen
Phosphorus
Herbicides/pesticides
Turbidity/opacity
Suspended/floating matter
Trash loading
Odor
Visual resource improvement based
on landscape control point surveys
Recreational use surveys
Community participation in
management
Table 6.2: Environmental
management.
Source: Kondolf and
Micheli 1995.
Monitoring plan. Development of a
monitoring plan is an important and
often ignored component of a moni-
toring cost assessment. The plan
should determine monitoring goals,
acceptable and unacceptable results,
and potential contingencies for
addressing unacceptable results
(Figure 6.19). The plan should speci-
fy responsibilities of participants.
Quality assurance (QA). The monitor-
ing plan should include an indepen-
Restoration Monitoring, Evaluation, and Adaptive Management
6-29
-------
dent review to ensure that the
plan meets the restoration goals,
the data quality objectives, and
the expectations of the restora-
tion manager. The major cost
component of quality assurance
is labor.
Data management. Monitoring
plans should have data manage-
ment specifications that start
with sample tracking (i.e., that
define the protocols and proce-
dures) and conclude with the
final archiving of the informa-
tion. Major costs include staff
labor time for data manage-
ment, data entry, database main-
tenance, computer time, and
data audits.
Field sampling plan. Sampling
may range from the very simple,
such as photo monitoring, wildlife
observation, and behavioral observa-
tion (e.g., feeding, resting, move-
ment), to the more complex, such as
nutrient and contaminant measure-
ment, water quality parameter mea-
surement, plankton group measure-
ment, productivity measurement in
water column and substrate surface,
macrophyte or vegetation sampling,
and hydrological monitoring. The
cost components for a complex plan
may include the following:
Restoration management and field
staff labor.
Subcontracts for specific field sam-
pling or measurement activities
(including costs of managing and
overseeing the subcontracted
activities).
Mobilization and demobilization
costs.
Purchase, rental, or lease of
equipment.
Supplies.
Figure 6.19: Monitoring. It is important to
develop a framework for the monitoring
protocol and a plan for monitoring evaluation.
Travel.
Shipping.
Laboratory sample analysis. Laboratory
analyses can range from simple tests
of water chemistry parameters such
as turbidity, to highly complex and
expensive tests, such as organic cont-
aminant analyses and toxicity assays.
The cost components of laboratory
sample analysis are usually estimated
in terms of dollars per sample.
Data analysis and interpretation.
Analysis and interpretation require
the expertise of trained personnel
and may include database manage-
ment, which can be conducted by a
data management specialist if the
data are complex or by a technician
or restoration manager if they are
relatively straightforward.
6-30
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Report preparation. One of the final
steps in the monitoring plan is to
prepare a report outlining the
restoration action, monitoring goals,
methods, and findings. These docu-
ments are meant to serve as interpre-
tative reports, synthesizing the field
and lab data analysis results. These
reports are typically prepared by a
research scientist with the aid of a
research assistant. Report production
costs depend on the type and quality
of reports requested.
Presentation of results. Though not
often considered a critical compo-
nent of a monitoring plan, presenta-
tion of plan results should be consid-
ered, including costs for labor and
travel.
Step 6: Categorize the Types of
Data
Several types of data gathered as part of
the monitoring plan may be useful in
developing the plan or may provide ad-
ditional information on the perfor-
mance of the system. The restoration
manager should also be aware of avail-
able information that is not part of the
monitoring plan but could be useful.
Consultation with agency personnel,
local universities and consultants, citi-
zen environmental groups (e.g.,
Audubon chapters), and landowners in
the area can reveal important informa-
tion.
Step 7: Determine the Level of
Effort and Duration
How much monitoring is required? The
answer to this question is dependent on
the goals and performance criteria for
the restoration as well as on the type of
ecological system being restored. A
monitoring plan does not need to be
complex and expensive to be effective.
Incorporate Landscape Ecology
The restoration size or scale affects the
complexity of the monitoring required.
As heterogeneity increases, the problem
of effectively sampling the entire system
becomes more complex. Consideration
must be given to the potential effect on
the restoration success of such things as
road noise, dogs, dune buggies, air pol-
lution, waterborne contamination,
stream flow diversions, human tram-
pling, grazing animals, and myriad
other elements (Figure 6.20).
Types of Data Important to Various Phases of the
Restoration
Restoration Planning
m Develop baseline data at the site.
Implementation of Restoration Plan
m Monitor implementation activities.
m Collect as-built or as-implemented information.
Postimplementation
m Collect performance data.
m Conduct other studies as needed.
Restoration Monitoring, Evaluation, and Adaptive Management
6-31
-------
Figure 6.20: Streams
in the (a) western
and (b) eastern
United States. The
wide variability of
stream structure and
function among dif-
ferent regions of the
country makes stan-
dardized restoration
evaluation difficult.
Determine Timing, Frequency, and
Duration of Sampling
The monitoring plan should be carried
out according to a systematic schedule.
The plan should include a start date,
the time of the year during which field
studies should take place, the frequency
of field studies, and the end date for the
plan. Timing, frequency, and duration
are dependent on the aspects of system
type and complexity, controversy, and
uncertainty.
Timing. The monitoring plan should
be designed prior to conducting any
baseline studies. A problem often
encountered with this initial sam-
pling is seasonality. Implementation
may be completed in midwinter,
when vegetation and other condi-
tions are not as relevant to the per-
formance criteria and goals of the
restoration, which might focus on
midsummer conditions.
The field studies should be carried
out during an appropriate time of
the year. The driving consideration is
the performance criteria. Because
weather varies from year to year, it is
wise to "bracket" the season with the
sampling. For example, sampling
temperature four times during the
midsummer may be better than a
single sampling in the middle of the
season. Sampling can be performed
either by concentrating all tasks dur-
ing a single site visit or by carrying
out one task or a similar set of tasks
at several sites in a single day.
Frequency. Frequency of sampling
refers to the period of time between
samplings. In general, "new" systems
change rapidly and should be moni-
tored more often than older systems.
As a system becomes established, it is
generally less vulnerable to distur-
bances. Hence, monitoring can be
less frequent. An example of this is
annual monitoring of a marsh for
the first 3 years, followed by moni-
toring at intervals of 2 to 5 years for
the duration of the planned restora-
tion or until the system stabilizes.
Duration. The monitoring plan
should extend long enough to pro-
vide reasonable assurances either that
the system has met its performance
criteria or that it will or will not like-
ly meet the criteria. A restored system
should be reasonably self-maintain-
ing after a certain period of time.
Fluctuations on an annual basis in
some parameters of the system will
occur even in the most stable mature
systems. It is important for the plan
to extend to a point somewhere after
the period of most rapid change and
into the period of stabilization of the
system.
6-32
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
Develop a Statistical Framework
The monitoring study design needs to
include consideration of statistical is-
sues, including the location of sample
collection, the number of replicate sam-
ples to collect, the sample size, and oth-
ers. Decisions should be made based on
an understanding of the accuracy and
precision required for the data (Figure
6.21). The ultimate use of the data must
be kept in mind when developing the
sampling plan. It is useful to frequently
ask, "Will this sampling method give us
the answers we need for planning?" and
"Will we be able to determine the suc-
cess or performance of the restoration?"
Monitoring can consist of many differ-
ent methods and can occur at varying
locations, times, and intensities, de-
pending on the conditions to be moni-
tored. The costs or expenditures of time
and resources also vary accordingly. The
challenge is to design the monitoring
plan to provide, in a cost-efficient and
timely manner, accurate information to
provide the rationale for decisions
made throughout the planning process,
and during and after implementation to
assess success.
The accuracy of the data to define envi-
ronmental conditions is of paramount
concern, but the acceptable precision of
the data can vary, depending on the tar-
get of concern. For example, if the
amount of pesticides in surface water is
a concern, it is much cheaper to assay
for the presence of groups of pesticides
than to test for specific ones. Also, if
overall water quality conditions are
needed, seasonal sampling of biological
indicators may act as a surrogate for
long-term sampling of specific chemical
parameters.
Choose the Sampling Level
The appropriate level of sampling or
the number of replicates under any par-
ticular field or laboratory sampling ef-
high bias
+ low precision
= low accuracy
low bias
+ low precision
= low accuracy
high bias
+ high precision
= low accuracy
low bias
+ high precision
= high accuracy
Figure 6.21: Patterns of shots at a target.
Monitoring design decisions should be made
based on an understanding of the accuracy
and precision required of the data.
Source: Gilbert 1987 after Jessen 1978.
fort depends on the information re-
quired and the level of accuracy needed.
Quantity and quality of information de-
sired is in turn dependent in part on
the expenditures necessary to carry out
the identified components of the sam-
pling plan.
Implementing and Managing
the Monitoring Plan
Management of the monitoring plan is
perhaps the least appreciated but one of
the most important components of
restoration. Because monitoring contin-
ues well after implementation activities,
there is a natural tendency for the plan
to lose momentum, for the data to ac-
cumulate with little analysis, and for lit-
tle documentation and dissemination
of the information to occur. This sec-
tion presents methods for preventing or
minimizing these problems.
Restoration Monitoring, Evaluation, and Adaptive Management
6-33
-------
Envisioning the Plan
The restoration manager must have a vi-
sion of the life (i.e., duration) of the
monitoring plan and must see how the
plan fits into the broader topic of
restoration as a viable tool for meeting
the goals of participating agencies, orga-
nizations, and sponsors.
Determining Roles
Carrying out the monitoring plan is
usually the responsibility of the restora-
tion sponsor. However, responsibility
should be established clearly in writing
during the development of the restora-
tion because this responsibility can last
for a decade or more.
Ensuring Quality
The restoration manager should con-
sider data quality as a high priority in
the monitoring plan. Scientifically de-
fensible data require that at least mini-
mal quality assurance procedures be in
place.
Interpreting Results
Results of the monitoring plan should
be interpreted with objectivity, com-
pleteness, and relevance to the restora-
tion objectives. The restoration manager
and the local sponsor may share re-
sponsibility in interpreting the results
generated by the monitoring plan. The
roles of the restoration manager and
local sponsor need to be determined
before any data-gathering effort begins.
Both parties should seek appropriate
technical expertise as needed.
Managing Data
Data should be stored in a systematic
and logical manner that facilitates
analysis and presentation. Development
of the monitoring plan should address
the types of graphs and tables that will
be used to summarize the results of the
monitoring plan. Most monitoring data
sets can be organized to allow direct
graphing of the data using database or
spreadsheet software.
Managing Contracts
One of the most difficult aspects of
managing a monitoring plan can be
management of the contracts required
to conduct the plan. Most restoration
requires that at least some of the work
be contracted to a consultant or an-
other agency. Because monitoring plans
are frequently carried out on a seasonal
basis, timing is important.
Restoration Evaluation
Directly linked to monitoring is the
evaluation of the success of the restora-
tion effort. Restoration evaluation is in-
tended to determine whether
restoration is achieving the specific
goals identified during planning,
namely, whether the stream corridor
has reestablished and will continue to
maintain the conditions desired.
Approaches to evaluation most often
emphasize biological features, physical
attributes, or both. The primary tool of
evaluation is monitoring indicators of
stream corridor structure, function, and
condition that were chosen because
they best estimate the degree to which
restoration goals were met.
Evaluation may target certain aquatic
species or communities as biological in-
dicators of whether specific water qual-
ity or habitat conditions have been
restored. Or, for example, evaluation
may focus on the physical traits of the
channel or riparian zone that were in-
tentionally modified by project imple-
mentation (Figure 6.22). In any case,
the job is not finished unless the condi-
tion and function of the modified
stream corridor are assessed and adjust-
6-34
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
ments, if necessary, are made. The time
frame for evaluating restoration success
can vary from months to years, depend-
ing on the speed of the stream system's
response to the treatment applied.
Therefore, performance evaluation often
means a commitment to evaluate
restoration long after it was imple-
mented.
Reasons to Evaluate Restoration
Efforts
The evaluation of stream corridor
restoration is a key step that is often
omitted. Kondolf and Micheli (1995)
indicate that despite increased commit-
ment to stream restoration, postrestora-
tion evaluations have generally been
neglected. In one study in Great Britain,
only 5 of almost 100 river conservation
enhancement projects had postimple-
mentation appraisal reports (Holmes
1991).
Why do practitioners of restoration
sometimes leave out the final evalua-
tion process? One probable reason is
that evaluation takes time and money
and is often seen as expendable excess
in a proposed restoration effort when it
is misunderstood. It appears that the
final restoration evaluation is some-
times abandoned so the remaining time
and money can be spent on the restora-
tion itself. Although an understandable
temptation, this is not an acceptable
course of action for most restoration ef-
forts, and collectively the lack of evalua-
tion slows the development and
improvement of successful restoration
techniques.
Protecting the Restoration
Investment
Stream corridor restoration can be ex-
tremely costly and represent substantial
financial losses if it fails to work prop-
erly. Monitoring during and after the
restoration is one way to detect prob-
lems before they become prohibitively
complex or expensive to correct.
Restoration may involve a commitment
of resources from multiple agencies,
Figure 6.22: Instream modifications. Restoration evaluation may focus on the physical traits of
the channel that were intentionally modified during project implementation such as the riffles
pictured.
Restoration Monitoring, Evaluation, and Adaptive Management
6-35
-------
REVERSE
Review Chapter
5's goals and
objectives
section.
groups, and individuals to achieve a va-
riety of objectives within a stream corri-
dor. All participants have made an
investment in reaching their own goals.
Reaching consensus on restoration
goals is a process that keeps these par-
ticipants aware of each others' aims.
Evaluating restoration success should
maintain the existing group awareness
and keep participants involved in help-
ing to protect their own investment.
Helping to Advance Restoration
Knowledge for Future
Applications
Restoration actions are relatively new
and evolving and have the risk of fail-
ure that is inherent in efforts with lim-
ited experience or history. Restoration
practitioners should share their experi-
ences and increase the overall knowl-
edge of restoration practicesthose that
work and those that do not. Shared ex-
perience is essential to our limited
knowledge base for future restoration.
Maintaining Accountability to
Restoration Supporters
The coalition of forces that make a
restoration effort possible can include a
wide variety of interest groups, active
participants, funding sources, and polit-
ical backers, and all deserve to know
the outcome of what they have sup-
ported. Sometimes, restoration moni-
toring may be strongly recommended
or required by regulation or as a condi-
tion of restoration funding. For exam-
ple, the USEPA has listed an evaluation
and reporting plan in guidance for
grants involving restoration practices to
reduce nonpoint source pollution. Re-
quirements notwithstanding, it is
worthwhile to provide the restoration
effort's key financial supporters and
participants with a final evaluation.
Other benefits such as enhancing public
relations or gaining good examples of
restoration successes and publishable
case histories, can also stem from well-
designed, well-executed evaluations.
Acting on the Results
Identified goals and objectives, as dis-
cussed in Chapter 5, should be very
clear and specific concerning the result-
ing on-site conditions desired. However,
large or complex restoration efforts are
sometimes likely to involve a wide
range of goals. Restoration evaluations
are needed to determine whether the
restoration effort is meeting and will
continue to meet specific goals identi-
fied during planning, to allow for mid-
Reasons to Prepare Written Documentation for the
Monitoring Plan
Demonstrates that the monitoring plan is "happening."
Demonstrates that the restoration meets the design specifications and perfor-
mance criteria.
Assists in discussions with others about the restoration.
Documents details that may otherwise be forgotten.
Provides valuable information to new participants.
Informs decision makers.
6-36
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
course adjustments, and to report on
any unanticipated benefits or problems
as a result of the program.
The results from a monitoring plan are
an important tool for assessing the
progress of a restoration and informing
restoration decision makers about the
potential need for action.
Alternative Actions
Because restoration involves natural sys-
tems, unexpected consequences of
restoration activities can occur. The four
basic options available are as follows:
No action. If the restoration is gener-
ally progressing as expected or if
progress is slower than expected but
will probably meet restoration goals
within a reasonable amount of time,
no action is appropriate.
Maintenance. Physical actions might
be required to keep restoration devel-
opment on course toward its goals.
Adding, abandoning, or decommission-
ing plan elements. Significant changes
in parts of the implemented restora-
tion plan might be needed. These
entail revisiting the overall plan, as
well as considering changes in the
design of individual elements.
Modification of restoration goals.
Monitoring might indicate that the
restoration is not progressing toward
the original goals, but is progressing
toward a system that has other highly
desirable functions. In this case, the
participants might decide that the
most cost-effective action would be
to modify the restoration goals rather
than to make extensive physical
changes to meet the original goals
for the restoration.
Adaptive Management
The expectations created during the de-
cision to proceed with restoration
Adaptive management is not
"adjustment management" but a
way of establishing hypotheses
early in the planning, then treat-
ing the restoration process as
an experiment to test the
hypotheses.
might not always influence the out-
come, but they are certainly capable of
influencing the opinions of participants
and clients concerning the outcome.
The first fundamental rule, then, is to
set proper expectations for the restora-
tion effort. If the techniques to be used
are experimental, have some risk of fail-
ure, or are likely to need midcourse cor-
rections, these facts need to be made
clear. One effective way to set reason-
able expectations from the beginning is
to acknowledge uncertainty, evaluation
of performance, and adjustments as
part of the game plan.
Adaptive management involves adjust-
ing management direction as new infor-
mation becomes available (Figure
6.23). It requires willingness to experi-
ment scientifically and prudently, and
to accept occasional failures (Intera-
gency Ecosystem Management Task
Force 1995). Since restoration is a new
science with substantial uncertainty,
adaptive management to incorporate
new midcourse information should be
expected. Moreover, through adaptive
management specific problems can be
focused on and corrected.
It is recognized that restoration is un-
certain. Therefore, it is prudent to allow
for contingencies to address problems
during or after restoration implementa-
tion. The progress of the system should
be assessed annually. At that time, deci-
Restoration Monitoring, Evaluation, and Adaptive Management
6-37
-------
plan
rc adaptive
-^ management
i Modify plans using monitoring, technical, and social
feedback
i Track restoration policy, programs, and individual pro-
jects as feedback for further restoration policy and
program redesign
i Restoration initiatives: recommend annual assessments
, use monitoring data and other data/expertise
m midcourse corrections or alternative actions
, link reporting/monitoring schedules for midcourse
corrections
Manager may contract some/all monitoring, but peri-
odically must visit sites, review reports, discuss with
contractors.
Figure 6.23: Adaptive management.
Adjusting management direction as new
information becomes available requires a
willingness to experiment and accept
occassional failures.
sions can be made regarding any mid-
course corrections or other alternative
actions, including modification of
goals. The annual assessments would
use monitoring data and might require
additional data or expertise from out-
side the restoration team. Because the
overall idea is to make the restoration
"work," while not expending large
amounts of funds to adhere to inflexi-
ble and unrealistic goals, decisions
would be made regarding the physical
actions that might be needed versus al-
terations in restoration goals.
Restoration participants must remain
willing to acknowledge failures and to
learn from them. Kondolf (1995) em-
phasizes that even if restoration fails, it
provides valuable experimental results
that can help in the design of future ef-
forts. Repeatedly, a cultural reluctance
to admit failure perpetuates the same
mistakes instead of educating others
about pitfalls that might affect their ef-
forts, too. Accepting failure reiterates
the importance of setting appropriate
expectations. Participants should all ac-
knowledge that failure is one of the
possible outcomes of restoration.
Should failure occur, they should resist
the natural temptation to bury their dis-
appointment and instead help others to
learn from their experience.
Documenting and Reporting
The monitoring report should also in-
clude a systematic review of changes in
resource management priorities and wa-
tershed conditions along with a discus-
sion of the possible implications for
restoration measures and objectives.
The review should be wide-ranging, in-
cluding observations and concerns that
might not require immediate attention
but should be documented to ensure
continuity in case of turnover in per-
sonnel. The monitoring report should
alert project managers to proposed de-
velopments or regulation changes that
could affect the restoration effort, so
that feedback can be provided and
stream corridor concerns can be consid-
ered during planning for the proposed
developments.
Documentation and reporting of the
progress and development of the
restoration provide written evidence
that the restoration manager can use for
a variety of purposes. Three simple con-
cepts are common among the best-
documented restorations:
6-38
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
A single file that was the repository
of all restoration information was
developed.
The events and tasks of the restora-
tion were recorded chronologically in
a systematic manner.
Well-written documents (i.e., plan-
ning and monitoring documents)
were produced and distributed wide-
ly enough to become part of the gen-
eral regional or national awareness of
the restoration.
Main sections in a general format for a
monitoring report should include title
page, summary or abstract, introduc-
tion, site description, methods, results,
discussion, conclusions, recommenda-
tions, acknowledgments, and literature
cited.
Dissemination of the Results
Recipients of the report and other mon-
itoring information should include all
interested parties (e.g., all state and fed-
eral agencies involved in a permit ac-
tion). In addition, complete files
should be maintained. The audience
can include beach-goers, birders, fish-
ers, developers, industry representatives,
engineers, government environmental
managers, politicians, and scientists.
The recipient list and schedule for deliv-
ery of the reports should be developed
by the restoration manager. If appropri-
ate, a meeting with interested parties
should be held to present the results of
the monitoring effort and to discuss the
future of the restoration. Large, com-
plex, and expensive restorations might
have wide appeal and interest, and
meetings on these restorations will re-
quire more planning. Presentations
should be tailored to the audience to
provide the information in the clearest
and most relevant form.
Planning for Feedback During
Restoration Implementation
A sound quality control/quality assur-
ance component of the restoration plan
incorporates the means to measure and
control the quality of an activity so that
it meets expectations (USEPA 1995a).
Especially in restoration efforts that in-
volve substantial earthmoving and
other major structural modifications,
risk of unintentional damage to water
quality or aquatic biota exists. Mid-
course monitoring should be part of the
plan, both to guard against unexpected
additional damage and to detect posi-
tive improvements (Figure 6.24).
Making a Commitment to the
Time Frame Needed to Judge
Success
The time required for system recovery
should be considered in determining
the frequency of monitoring.
Data on fractions of an hour might
be needed to characterize streamflow.
$
~
Figure 6.24: Streambank failure. Midcourse
monitoring will guard against unexpected
damages.
Restoration Monitoring, Evaluation, and Adaptive Management
6-39
-------
Hourly data might be needed for
water temperature and water quality.
Weekly data might be appropriate to
show changes in the growth rate of
aquatic organisms.
Monthly or quarterly data might be
necessary to investigate annual cycles.
Annual measures might be adequate
to show the stability of streambanks.
Organisms with long life spans, such
as paddlefish or trees, might need to
be assessed only on the order of
decades (Figure 6.25).
The time of day for measurement
should also be considered. It might be
most appropriate to measure dissolved
oxygen at dawn, whereas temperature
might be measured most appropriately
in the mid- to late afternoon. Migra-
tions or climatic patterns might require
that studies be conducted during spe-
cific months or seasons. For example,
restoration efforts expected to result in
increased baseflow might require stud-
ies only in late summer and early fall.
The expected time for recovery of the
stream corridor could involve years or
decades, which should be addressed in
the duration of the study and its evalua-
tion. Moreover, if the purpose of
restoration is to maintain natural flood-
plain functions during a 10-year flood
event, it might take years for such an
event to occur and allow a meaningful
evaluation of performance.
Some efforts have been made to inte-
grate short- and long-term performance
monitoring requirements into overall
design. Bryant (1995) recently pre-
sented the techniques of a pulsed moni-
toring strategy involving a series of
Figure 6.25: Revegetated streambank.
Monitoring and evaluation must take into
account the differences in life spans among
organisms. Tree growth along the streambank
will be evaluated on a much longer time scale
than other restoration results.
6-40
Chapter 6: Implementing, Monitoring, Evaluating, and Adapting
-------
short-term, high-intensity studies sepa-
rated by longer periods of low-intensity
data collection. MacDonald et al.
(1991) have described several different
types of monitoring by frequency, dura-
tion, and intensity.
Evaluating Changes in the
Sources of Stress as Well as in
the System Itself
Restoration might be necessary because
of stress currently affecting the stream
corridor or because of damage in the
past. It is critical to know whether the
sources of stress are still present or are
absent, and to incorporate treatment of
the sources of stress as part of the
restoration approach. In fact, some
practitioners will not enter into a
restoration effort that does not include
reducing or eliminating the source of
negative impacts because simply im-
proving the stream itself will likely re-
sult in only temporary enhancements.
The beginning steps of ecological risk
assessment are largely designed around
characterization of an ecosystem's val-
ued features, characterization of the
stressors degrading the ecosystem, iden-
tification of the routes of exposure of
the ecosystem to the stressors, and de-
scription of ecological effects that might
result. If these factors are documented
for restoration during its design and ex-
ecution, it should be clear how evaluat-
ing performance should address each
factor after completion. Has the source
of stress, or its route of exposure, been
diminished or eliminated? Are the neg-
ative ecological effects reversed or no
longer present?
Restoration Monitoring, Evaluation, and Adaptive Management
6-41
-------
-------
Part III
ppiying
Restoratic
Principles
tout stake
brush mattress
centerline of
swale or ditch
September October
A B C D E F G
i i i i i i
0 10 20 30 40 50 60 7C
Hours
-------
-------
Analysis o
Corridor
Condition
-------
7.A Hydrologic and Hydraulic Processes
How does the stream flow and why is this understanding important?
Is streamflow perennial, ephemeral or intermittent?
What is the discharge, frequency and duration of extreme high and low flows?
How often does the stream flood?
How does roughness affect flow levels?
What is the discharge most effective in maintaining the stream channel under
equilibrium conditions?
How does one determine if equilibrium conditions exist?
What field measurements are necessary?
7.B Geomorphic Processes
How do I inventory geomorphic information on streams and use it to understand and
develop physically appropriate restoration plans?
How do I interpret the dominant channel adjustment processes active at the site?
How deep and wide should a stream be?
Is the stream stable?
Are basin-wide adjustments occurring, or is this a local problem?
Are channel banks stable, at-risk, or unstable?
What measurements are necessary?
7.C Chemical Processes
How do you measure the condition of the physical and chemical conditions within a
stream corridor?
Why is quality assurance an important component of stream corridor analysis activities?
What are some of the water quality models that can be used to evaluate water
chemistry data ?
7.D Biological Characteristics
What are some important considerations in using biological indicators for analyzing
stream corridor conditions?
Which indicators have been used successfully?
What role do habitat surveys play in analyzing the biological condition of the
stream corridor?
How do you measure biological diversity in a stream corridor?
What is the role of stream classification systems in analyzing stream corridor conditions?
How can models be used to evaluate the biological condition of a stream corridor?
What are the characteristics of models that have been used to evaluate stream
corridor conditions?
-------
Applying
Restoration
Principles
Chapter 7: Analysis of Corridor Condition
Chapter 8: Restoration Design
Chapter 9: Restoration Installation,
Monitoring, and Management
Stream corridor functions are recogniz-
able and definable for the smallest
study area as well as for eco-regional lev-
els. Because a corridor functions at all
scales, the principles of restoration should
be applied using those appropriate to the
scale of concern.
Part III of this document is the "how to"
section. The understanding gained in Part
I and developed into a restoration plan in
Part II is applied. Part III shows how condi-
tion analysis and design can lead to
restoring corridor structure and the habi-
tat, conduit, filter/barrier, source, and sink
functions.
m Chapter 7 discusses the measurement
and analysis of corridor condition. The
analysis is broken down by scale and
process.
m Physical processes, structures, and
functions
-------
Geomorphic and hydrological
m Water chemistry
m Biological analysis
This breakdown allows the
generation of a "picture" of
stream corridor conditions that
comes into clearer focus as one
descends in scale from maps
and aerial photographs to the
streambed.
Chapter 8 contains design guid-
ance and techniques to restore
stream corridor structure and
functions. It is not, however, a
cookbook of prescribed solu-
tions.
Chapter 9 deals with construc-
tion topics that can occur after
the stream corridor restoration
design is complete and required
permits are obtained. Careful
construction and field inspection
are necessary to ensure that the
corridor is not degraded by con-
struction activities. At the end of
successful restoration, the stream
must be managed, maintained,
and monitored to ensure goals
and objectives are being met.
111-2
Part III: Applying Restoration Principles
-------
Analysis of
Corridor
Condition
7.A Hydrologic Processes
7.B Geomorphic Processes
7.C Chemical Characteristics
7.D Biological Characteristics
Section 7.A: Hydrologic Processes
Understanding how water flows into and
through stream corridors is critical to de-
veloping restoration initiatives. How fast,
how much, how deep, how often, and
when water flows are important basic
questions that must be answered in order
to make appropriate decisions about the
implementation of a stream corridor's
restoration.
Section 7.5: Geomorphic Processes
This section combines the basic hydro/ogle
processes with the physical or geomorphic
functions and characteristics. Water flows
through streams but is affected by the
kinds of soils and alluvial features within
the channel, in the floodplain, and in the
uplands. The amount and kind of sedi-
ments carried by a stream is largely a de-
terminant of its equilibrium characteristics,
including size, shape, and profile. Success-
ful implementation of the stream corridor
restoration, whether active (requiring di-
rect intervention) or passive, (removing
only disturbance factors), depends on an
understanding of how water and sedi-
ment are related to channel form and
function, and on what processes are in-
volved with channel evolution.
-------
Section 7.C: Chemical
Characteristics
The quality of water in the stream
corridor is normally a primary ob-
jective of restoration, either to im-
prove it to a desired condition, or
to sustain it. Restoration initiatives
should consider the physical and
chemical characteristics that may
not be readily apparent but that are
nonetheless critical to the functions
and processes of stream corridors.
Chemical manipulation of specific
characteristics usually involves the
management or alteration of ele-
ments in the landscape or corridor.
Section 7.D: Biological
Characteristics
The fish, wildlife, plants, and
human beings that use, live in, or
just visit the stream corridor are key
elements to consider, not only in
terms of increasing populations or
species diversity, but also in terms
of usually being one of the primary
goals of the restoration effort. A
thorough understanding of how
water flows, how sediment is trans-
ported, and how geomorphic fea-
tures and processes evolve is
important. However, a prerequisite
to successful restoration is an un-
derstanding of the living parts of
the system and how the physical
and chemical processes affect the
stream corridor.
7-2
Chapter 7: Analysis of Corridor Condition
-------
7.A Hydrologic Processes
Flow Analysis
Restoring stream structure and function
requires knowledge of flow characteris-
tics. At a minimum, it is helpful to
know whether the stream is perennial,
intermittent, or ephemeral, and the rel-
ative contributions of baseflow and
stormflow in the annual runoff. It
might also be helpful to know whether
streamflow is derived primarily from
rainfall, snowmelt, or a combination of
the two.
Other desirable information includes
the relative frequency and duration of
extreme high and low flows for the site
and the duration of certain stream flow
levels. High and low flow extremes usu-
ally are described with a statistical pro-
cedure called a frequency analysis, and
the amount of time that various flow
levels are present is usually described
with a flow duration curve.
Finally, it is often desirable to
estimate the channel-forming or domi-
nant discharge for a stream (i.e., the
discharge that is most effective in
shaping and maintaining the natural
stream channel). Channel-forming or
dominant discharge is used for design
when the restoration includes channel
reconstruction.
Estimates of streamflow characteristics
needed for restoration can be obtained
from stream gauge data. Procedures for
determining flow duration characteris-
tics and the magnitude and frequency
of floods and low flows at gauged sites
are described in this section. The pro-
cedures are illustrated using daily
mean flows and annual peak flows
(the maximum discharge for each year)
for the Scott River near Fort Jones, a
653-square-mile watershed in northern
California.
Most stream corridor restoration initia-
tives are on streams or reaches that lack
systematic stream gauge data. Therefore,
estimates of flow duration and the fre-
quency of extreme high and low flows
must be based on indirect methods
from regional hydrologic analysis. Sev-
eral methods are available for indirect
estimation of mean annual flow and
flood characteristics; however, few
methods have been developed for esti-
mating low flows and general flow du-
ration characteristics.
Users are cautioned that statistical
analyses using historical streamflow
data need to account for watershed
changes that might have occurred dur-
ing the period of record. Many basins
in the United States have experienced
substantial urbanization and develop-
ment; construction of upstream reser-
voirs, dams, and storm water
management structures; and construc-
tion of levees or channel modifications.
These features have a direct impact on
the statistical analyses of the data for
peak flows, and for low flows and flow
duration curves in some instances. De-
pending on basin modifications and
the analyses to be performed, this could
require substantial time and effort.
Flow Duration
The amount of time certain flow levels
exist in the stream is represented by a
flow duration curve which depicts the
percentage of time a given streamflow
was equaled or exceeded over a given
period. Flow duration curves are usually
based on daily streamflow (a record
containing the average flow for each
day) and describe the flow characteris-
tics of a stream throughout a range of
discharges without regard to the se-
quence of occurrence. A flow duration
Hydrologic Processes
7-3
-------
curve is the cumulative histogram of the
set of all daily flows. The construction
of flow duration curves is described by
Searcy (1959), who recommends defin-
ing the cumulative histogram of stream-
flow by using 25 to 35 well-distributed
class intervals of streamflow data.
Figure 7.1 is a flow duration curve that
was defined using 34 class intervals and
software documented by Lumb et al.
(1990). The numerical output is pro-
vided in the accompanying table.
The curve shows that a daily mean flow
of 1,100 cubic feet per second (cfs) is
exceeded about 20 percent of the time
or by about 20 percent of the observed
daily flows. The long-term mean daily
flow (the average flow for the period of
record) for this watershed was deter-
mined to be 623 cfs. The duration curve
shows that this flow is exceeded about
38 percent of the time.
For over half the states, the USGS has
published reports for estimating flow
duration percentiles and low flows at
ungauged locations. Estimating flow
duration characteristics at ungauged
sites usually is attempted by adjusting
data from a nearby stream gauge in a
hydrologically similar basin. Flow dura-
tion characteristics from the stream
gauge record are expressed per unit area
of drainage basin at the gauge (i.e., in
cfs/mi2) and are multiplied by the
drainage area of the ungauged site to
estimate flow duration characteristics
there. The accuracy of such a procedure
is directly related to the similarity of the
two sites. Generally, the drainage area at
the stream gauge and ungauged sites
should be fairly similar, and streamflow
characteristics should be similar for
both sites. Additionally, mean basin ele-
vation and physiography should be
similar for both sites. Such a procedure
does not work well and should not be
attempted in stream systems dominated
by local convective storm runoff or
where land uses vary significantly be-
tween the gauged and ungauged basins.
Flow Frequency Analysis
The frequency of floods and low flows
for gauged sites is determined by ana-
lyzing an annual time series of maxi-
mum or minimum flow values (a
chronological list of the largest or
smallest flow that occurred each year).
Although previously described in Chap-
ter 1, flow frequency is redefined here be-
cause of its relevance to the sections
that follow. Flow frequency is defined
as the probability or percent chance of
a given flow's being exceeded or not ex-
ceeded in any given year. Flow fre-
quency is often expressed in terms of
recurrence interval or the average number
of years between exceeding or not ex-
ceeding the given flows. For example, a
given flood flow that has a 100-year re-
currence interval is expected to be ex-
ceeded, on average, only once in any
100-year period; that is, in any given
year, the annual flood flow has a 1 per-
cent chance or 0.01 probability of ex-
ceeding the 100-year flood. The
exceedance probability, p, and the re-
currence interval, T, are related in that
one is the reciprocal of the other (i.e.,
T = 1/p). Statistical procedures for de-
termining the frequency of floods and
low flows at gauged sites follow.
As mentioned earlier, most stream corri-
dor restoration initiatives are on
streams or reaches lacking systematic
stream gauge data; therefore, estimates
of flow duration characteristics and the
frequency of extreme high and extreme
low flows must be based on indirect
methods from regional hydrologic
analysis.
Flood Frequency Analysis
Guidelines for determining the fre-
quency of floods at a particular location
7-4
Chapter 7: Analysis of Corridor Condition
-------
using streamflow records are docu-
mented by the Hydrology Subcommit-
tee of the Interagency Advisory
Committee on Water Data (IACWD
1982, Bulletin 17B). The guidelines de-
scribed in Bulletin 17B are used by all
federal agencies in planning activities
involving water and related land re-
sources. Bulletin 17B recommends fit-
ting the Pearson Type III frequency
distribution to the logarithms of the an-
nual peak flows using sample statistics
(mean, standard deviation, and skew)
to estimate the distribution parameters.
Procedures for outlier detection and ad-
justment, adjustment for historical data,
development of generalized skew, and
weighting of station and generalized
skews are provided. The station skew is
computed from the observed peak
flows, and the generalized skew is a re-
gional estimate determined from esti-
mates at several long-term stations in
the region. The US Army Corps of Engi-
neers also has produced a user's manual
for flood frequency analysis (Report CPD-
13, 1994) that can aid in determining
flood frequency distribution parame-
ters. NRCS has also produced a manual
(National Engineering Handbook, Section
4, Chapter 18) that can also be used in
determining flood frequency distribu-
tion (USDA-SCS 1983).
Throughout the United States, flood fre-
quency estimates for USGS gauging sta-
tions have been correlated with certain
climatic and basin characteristics. The
result is a set of regression equations
that can be used to estimate flood mag-
nitude for various return periods in un-
gauged basins (Jennings et al. 1994).
Reports outlining these equations often
are prepared for state highway depart-
ments to help them size culverts and
rural road bridge openings.
Estimates of the frequency of peak
flows at ungauged sites may be made by
using these regional regression equa-
1 (Dcfs)hargeS E^ledTr Exceeded
106
105
^
S1°4
.0 103
1
g 102
£
10
1
^^^^^^^^^^^^^^^H
0
1
1.4
2
2.8
4
5.7
8.1
11
16
23
33
46
66
93
130
190
270
380
530
760
1,100
1,500
2,200
3,100
4,300
6,100
8,700
12,000
17,000
25,000
35,000
50,000
71,000
>
I I I l II
100
100
100
100
100
100
99
99
99
99
96
76
68
43
98.7
96.89
94.2
85.02
74.54
65.98
60.15
55.03
49.03
42.05
31.41
20.75
11.95
5.1
2.25
1.2
0
68
0.35
0.16
0.06
0.04
0.01
0
0
^^^
*"*x
i i
Cir*
Fig
du
ass
Da
ne,
I 19.
0.5 2510 30 50 80 95 99.5
% of Time Flow Equaled or Exceeded
Figure 7.1: Flow
duration curve and
associated data tables.
Data for the Scott River,
near Fort Jones, CA,
1951-1980, show that
a flow of 1,100 cubic
feet per second (cfs)
is exceeded about 20
percent of the time.
Source: Lumb et al. (1990).
Hydrologic Processes
7-5
-------
Sources of Daily Mean Discharge and Other Data from USGS Stream
Gauges
Daily Mean Streamflow
Daily mean streamflow data needed for defining
flow duration curves are published on a water-
year (October 1 to September 30) basis for each
state by the U.S. Geological Survey (USGS) in the
report series Water Resources Data. The data col-
lected and published by the USGS are archived in
the National Water Information System (NWIS).
The USGS currently provides access to streamflow
data by means of the Internet. The USGS URL
address for access to streamflow data is
http://water.usgs.gov. Approximately 400,000 sta-
tion years of historical daily mean flows for about
18,500 stations are available through this source.
The USGS data for the entire United States are
also available from commercial vendors on two
CD-ROMs, one for the eastern and one for the
western half of the country (e.g., CD-ROMs for
DOS can be obtained from Earth Info, and CD-
ROMs for Windows can be obtained from
Hydrosphere Data Products. Both companies are
located in Boulder, Colorado.)
In addition to the daily mean flows, summary sta-
tistics are also published for active streamflow sta-
tions in the USGS annual Water Resources Data
reports. Among the summary statistics are the
daily mean flows that are exceeded 10, 50, and
90 percent of the time of record. These durations
are computed by ranking the observed daily mean
flows from q(1) to q(n.36S) where n is the number of
years of record, qm is the largest observation, and
q , is the smallest observation. The ranked list
1(365'n)
is called a set of ordered observations. The qm that
are exceeded 10, 50, and 90 percent of the time
are then determined. Flow duration percentiles
(quantiles) for gauged sites are also published by
USGS in reports on low flow frequency and other
streamflow statistics (e.g., Atkins and Pearman
1994, Zalants 1991, Telis 1991, and Ries 1994).
Peak Flow
Annual peak flow data needed for flood frequen-
cy analysis are also published by the USGS,
archived in NWIS, and available through the inter-
net at the URL address provided above. Flood fre-
quency estimates at gauged sites are routinely
published by USGS as part of cooperative studies
with state agencies to develop regional regression
equations for ungauged watersheds. Jennings et
al. (1994) provide a nationwide summary of the
current USGS reports that summarize flood fre-
quency estimates at gauged sites as well as
regression equations for estimating flood peak
flows for ungauged watersheds. Annual and
partial-duration (peaks-above-threshold) peak flow
data for all USGS gauges can be obtained on one
CD-ROM from commercial vendors.
7-6
Chapter 7: Analysis of Corridor Condition
-------
tions, provided that the gauged and un-
gauged sites have similar climatic and
physiographic characteristics.
Frequently the user needs only such
limited information as mean annual
precipitation, drainage area, storage in
lakes and wetlands, land use, major soil
types, stream gradients, and a topo-
graphic map to calculate flood magni-
tudes at a site. Again, the accuracy of
the procedure is directly related to the
hydrologic similarity of the two sites.
Similarly, in many locations, flood fre-
quency estimates from USGS gauging
stations have been correlated with cer-
tain channel geometry characteristics.
These correlations produce a set of re-
gression equations relating some chan-
nel feature, usually active channel
width, to flood magnitudes for various
return periods. A review of these equa-
tions is provided by Wharton (1995).
Again, the standard errors of the esti-
mate might be large.
Regardless of the procedure or source of
information chosen for obtaining flood
frequency information, estimates for
the 1.5, 2, 5, 10, 25, and (record per-
mitting) 50 and 100-year flood events
may be plotted on standard log-
probability paper, and a smooth curve
may be drawn between the points.
(Note that these are flood events with
probabilities of 67, 50, 20, 10, 4, 2, and
1 percent, respectively.) This plot be-
comes the flood frequency relationship
for the restoration site under considera-
tion. It provides the background infor-
mation for determining the frequency
of inundation of surfaces and vegeta-
tion communities along the channel.
Low-Flow Frequency Analysis
Guidelines for low-flow frequency analysis
are not as standardized as those for
flood frequency analysis. No single fre-
quency distribution or curve-fitting
method has been generally accepted.
Flood Frequency Estimates
Flood frequency estimates also may be generated using
precipitation data and applicable watershed runoff models
such as HEC-1, TR-20, and TR-55. The precipitation record
for various return-period storm events is used by the
watershed model to generate a runoff hydrograph and
peak flow for that event. The modeled rainfall may be
from historical data or from an assumed time distribution
of precipitation (e.g., a 2-year, 24-hour rainfall event). This
method of generating flood frequency estimates assumes
the return period of the runoff event equals the return
period of the precipitation event (e.g., a 2-year rainfall
event will generate a 2-year peak flow). The validity of this
assumption depends on antecedent moisture conditions,
basin size, and a number of other factors.
Vogel and Kroll (1989) provide a sum-
mary of the limited number of studies
that have evaluated frequency distribu-
tions and fitting methods for low flows.
The methodology used by USGS and
USEPA is described below.
The hypothetical daily hydrograph
shown in Figure 7.2 is typical of many
areas of the United States where the an-
nual minimum flows occur in late sum-
mer and early fall. The climatic year
(April 1 to March 31) rather than the
water year is used in low-flow analyses
so that the entire low-flow period is
contained within one year.
Data used in low-flow frequency analy-
ses are typically the annual minimum
average flow for a specified number of
consecutive days. The annual minimum
7- and 14-day low flows are illustrated
in Figure 7.2. For example, the annual
minimum 7-day flow is the annual
minimum value of running 7-day
means.
Hydrologic Processes
7-7
-------
40
30
w
£20
I 15
Q
1
lowest average
14-day flow ^
lowest
average 7-day flow
_l_
August September
October
Figure 7.2: Annual hydrograph displaying low
flows. The daily mean flows on the lowest part
of the annual hydrograph are averaged to give
the 7-day and 14-day low flows for that year.
USGS and USEPA recommend using
the Pearson Type III distribution to the
logarithms of annual minimum d-day
low flows to obtain the flow with a
nonexceedance probability p (or recur-
rence interval T = 1/p). The Pearson
Type III low-flow estimates are com-
puted from the following equation:
where:
XdT = the logarithm of the annual
minimum d-day low flow for
which the flow is not exceeded
in 1 of T years or which has a
probability of p = 1/T of not
being exceeded in any given year
the mean of the logarithms of
annual minimum d-day low
flows
the standard deviation of the
logarithms of the annual mini-
mum d-day low flows
KT = the Pearson Type III frequency
factor
The desired quantile, QdT, can be ob-
tained by taking the antilogarithm of
the equation.
The 7-day, 10-year low flow (Q7 m) is
used by about half of the regulatory
agencies in the United States for man-
aging water quality in receiving waters
Md =
sd =
(USEPA 1986, Riggs et al. 1980). Low
flows for other durations and frequen-
cies are used in some states.
Computer software for performing low-
flow analyses using a record of daily
mean flows is documented by Hutchi-
son (1975) and Lumb et al. (1990). An
example of a low-flow frequency curve
for the annual minimum 7-day low
flow is given in Figure 7.3 for Scott
River near Fort Jones, California, for the
same period (1951 to 1980) used in the
flood frequency analyses above.
From Figure 7.3, one can determine
that the Q7 io is about 20 cfs, which is
comparable to the 99th percentile
(daily mean flow exceeded 99 percent
of the time) of the flow duration curve
(Figure 7.1). This comparison is consis-
tent with findings of Fennessey and
Vogel (1990), who concluded that the
Q710 from 23 rivers in Massachusetts
was approximately equal to the 99th
flow duration percentile. The USGS rou-
tinely publishes low flow estimates at
gauged sites (Zalants 1991, Telis 1991,
Atkins and Pearman 1994).
Following are discussions of different
ways to look at the flows that tend to
form and maintain streams. Restora-
tions that include alterations of flows or
changes in the dimensions of the
stream must include engineering analy-
ses as described in Chapter 8.
Channel-forming Flow
The channel-forming or dominant dis-
charge is a theoretical discharge that if
constantly maintained in an alluvial
stream over a long period of time
would produce the same channel geom-
etry that is produced by the long-term
natural hydrograph. Channel-forming
discharge is the most commonly used
single independent variable that is
found to govern channel shape and
form. Using a channel-forming dis-
charge to design channel geometry is
7-8
Chapter 7: Analysis of Corridor Condition
-------
io2
2
ns
U
10
7-day low flow
Log-Pearson Type
I
I
I
95 90 80 70 50 30 20
Annual Nonexceedance Probability (percent)
10
not a universally accepted technique, al-
though most river engineers and scien-
tists agree that the concept has merit, at
least for perennial (humid and temper-
ate) and perhaps ephemeral (semiarid)
rivers. For arid channels, where runoff is
generated by localized high-intensity
storms and the absence of vegetation
ensures that the channel will adjust to
each major flood event, the channel-
forming discharge concept is generally
not applicable.
Natural alluvial rivers experience a wide
range of discharges and may adjust
their geometry to flow events of differ-
ent magnitudes by mobilizing either
bed or bank sediments. Although Wol-
man and Miller (1960) noted that "it is
logical to assume that the channel
shape is affected by a range of flows
rather than a single discharge," they
concurred with the view put forward
earlier by civil engineers working on
"regime theory" that the channel-
forming or dominant discharge is the
steady flow that produces the same
gross channel shapes and dimensions
Figure 7.3: Annual minimum 7-day low flow
frequency curve. The Q,,, on this graph is about
20 cfs. The annual minimum value of 7-day
running means for this gauge is about W
percent.
as the natural sequence of events (Inglis
1949). Wolman and Miller (I960) de-
fined "moderate frequency" as events
occurring "at least once each year or
two and in many cases several or more
times per year." They also considered
the sediment load transported by a
given flow as a percentage of the total
amount of sediment carried by the river
during the period of record. Their re-
sults, for a variety of American rivers lo-
cated in different climatic and
physiographic regions, showed that the
greater part (that is, 50 percent or
more) of the total sediment load was
carried by moderate flows rather than
catastrophic floods. Ninety percent of
the load was carried by events with a re-
turn period of less than 5 years. The
precise form of the cumulative curve ac-
tually depends on factors such as the
Hydrologic Processes
7-9
-------
predominant mode of transport (bed
load, suspended load, or mixed load)
and the flow variability, which is influ-
enced by the size and hydrologic char-
acteristics of the watershed. Small
watersheds generally experience a wider
range of flows than large watersheds,
and this tends to increase the propor-
tion of sediment load carried by infre-
quent events. Thorough reviews of
arguments about the conceptual basis
of channel-forming discharge theory
can be found in textbooks by Richards
(1982), Knighton (1984), and Summer-
field (1991).
Researchers have used various discharge
levels to represent the channel-forming
discharge. The most common are (1)
bankfull discharge, (2) a specific dis-
charge recurrence interval from the an-
nual peak or partial duration frequency
curves, and (3) effective discharge.
These approaches are frequently used
and can produce a good approximation
of the channel-forming discharge in
many situations; however, as discussed
in the following paragraphs, consider-
able uncertainties are involved in all
three of these approaches. Many practi-
tioners are using specific approaches to
determine channel-forming discharge
and the response of stream corridors.
Bibliographic information on these
methods is available later in the
document.
Because of the spatial variability within
a given geographical region, the re-
sponse of any particular stream corridor
within the region can differ from that
expected for the region as a whole. This
is especially critical for streams draining
small, ungauged drainage areas. There-
fore, the expected channel-forming dis-
charge of ungauged areas should be
estimated by more than one alternative
method, hopefully leading to consistent
estimates.
Bankfull Discharge
The bankfull discharge is the discharge
that fills a stable alluvial channel up to
the elevation of the active floodplain.
In many natural channels, this is the
discharge that just fills the cross section
without overtopping the banks, hence
the term "bankfull." This discharge is
considered to have morphological sig-
nificance because it represents the
breakpoint between the processes of
channel formation and floodplain for-
mation. In stable alluvial channels,
bankfull discharge corresponds closely
with effective discharge and channel-
forming discharge.
The stage vs. discharge or rating curve
presented in Figure 7.4 was developed
for a hypothetical stream by computing
the discharge for different water surface
elevations or stages. Since discharges
greater than bankfull spread across the
active floodplain, stage increases more
gradually with increasing discharge
above bankfull than below bankfull,
when flows are confined to the channel.
Another method for determining the
bankfull stage and discharge is to deter-
mine the minimum value on a plot re-
lating water surface elevation to the
ratio of surface width to area. The fre-
quency of the bankfull discharge can be
determined from a frequency distribu-
tion plot like Figure 7.1.
Bankfull stage can also be identified
from field indicators of the elevation of
the active floodplain. The correspond-
ing bankfull discharge is then deter-
mined from a stage vs. discharge
relationship.
Field Indicators of Bankfull Discharge
Various field indicators can be used for
estimating the elevation of the stage as-
sociated with bankfull flow. Although
the first flat depositional surface is
often used, the identification of deposi-
tional surfaces in the field can be diffi-
7-10
Chapter 7: Analysis of Corridor Condition
-------
cult and misleading and, at the very
least, requires trained, experienced field
personnel. After an elevation is selected
as the bankfull, the stage vs. discharge
curve can be computed to determine
the magnitude of the discharge corre-
sponding to that elevation.
The above relationships seldom work in
incised streams. In an incised stream,
the top of the bank might be a terrace
(an abandoned floodplain), and indica-
tors of the active floodplain might be
found well below the existing top of
bank. In this situation, the elevation of
the channel-forming discharge will be
well below the top of the bank. In addi-
tion, the difference between the ordi-
nary use of the term "bankfull" and the
geomorphic use of the term can cause
major communication problems.
Field identification of bankfull eleva-
tion can be difficult (Williams 1978),
but is usually based on a minimum
width/depth ratio (Wolman 1955), to-
gether with the recognition of some dis-
continuity in the nature of the channel
banks such as a change in its sedimen-
tary or vegetative characteristics. Others
have defined bankfull discharge as
follows:
Nixon (1959) defined the bankfull
stage as the highest elevation of a
river that can be contained within
the channel without spilling water
on the river floodplain or washlands.
Wolman and Leopold (1957)
defined bankfull stage as the eleva-
tion of the active floodplain.
Woodyer (1968) suggested bankfull
stage as the elevation of the middle
bench of rivers having several over-
flow surfaces.
Pickup and Warner (1976) defined
bankfull stage as the elevation at
which the width/depth ratio
becomes a minimum.
-------
The reader is
cautioned that
the indicators
used to define
the bankfull
condition must
be spelled out
each time a
bankfull dis-
charge is used
in a project
plan or design.
gauge is located near the reach of inter-
est. Otherwise, discharge must be calcu-
lated using applicable hydraulic
resistance equations and, preferably,
standard hydraulic backwater tech-
niques. This approach typically requires
that an estimation of channel rough-
ness be made, which adds to the uncer-
tainty associated with calculated
bankfull discharge.
Because of its convenience, bankfull
discharge is widely used to represent
channel-forming discharge. There is no
universally accepted definition of bank-
full stage or discharge that can be consis-
tently applied, has general application,
and integrates the processes that create
the bankfull dimensions of the river.
The reader is cautioned that the indica-
tors used to define the bankfull condi-
tion must be spelled out each time a
bankfull discharge is used in a project
plan or design.
Determining Channel-Forming
Discharge from Recurrence Interval
To avoid some of the problems related
to field determination of bankfull stage,
the channel-forming discharge is often as-
sumed to be represented by a specific
recurrence interval discharge. Some re-
searchers consider this representative
discharge to be equivalent to the bank-
full discharge. Note that "bankfull dis-
charge" is used synonymously with
"channel-forming discharge" in this
document. The earliest estimate for
channel-forming discharge was the
mean annual flow (Leopold and Mad-
dock 1953). Wolman and Leopold
(1957) suggested that the channel-
forming discharge has a recurrence in-
terval of 1 to 2 years. Dury (1973)
concluded that the channel-forming
discharge is approximately 97 percent
of the 1.58-year discharge or the most
probable annual flood. Hey (1975)
showed that for three British gravel-bed
rivers, the 1.5-year flow in an annual
maximum series passed through the
scatter of bankfull discharges measured
along the course of the rivers. Richards
(1982) suggested that in a partial dura-
tion series bankfull discharge equals the
most probable annual flood, which has
a 1 year return period. Leopold (1994)
stated that most investigations have
concluded that the bankfull discharge
recurrence intervals ranged from 1.0 to
2.5 years. Pickup and Warner (1976)
determined bankfull recurrence inter-
vals ranged from 4 to 10 years on the
annual series.
However, there are many instances
where the bankfull discharge does not
fall within this range. For example,
Williams (1978) determined that ap-
proximately 75 percent of 51 streams
that he analyzed appeared to have recur-
rence intervals for the bankfull discharge
of between 1.03 and 5.0 years. Williams
used the elevation of the active flood-
plain or the valley flat, if no active
floodplain was defined at a station, as
the elevation of the bankfull surface in
his analyses. He did not establish
whether these streams were in equilib-
rium, so the validity of using the top of
the streambank as the bankfull elevation
is in question, especially for those sta-
tions with valley flats. This might ex-
plain the wide range (1.02 to 200 years)
he reported for bankfull discharge re-
turn intervals for streams with valley
flats as opposed to active floodplains.
The range in return intervals for 19 of
the 28 streams with active floodplains
was from 1.01 to 32 years. Nine of the
28 streams had bankfull discharge recur-
rence intervals of less than 1.0 year. It
should be noted that only 3 of those 28
streams had bankfull discharge recur-
rence intervals greater than 4.8 years.
About one-third of the active floodplain
stations had bankfull discharges near
the 1.5-year recurrence interval.
7-12
Chapter 7: Analysis of Corridor Condition
-------
effective discharge
Discharge
Figure 7.5: Effective discharge determination
from sediment rating and flow duration curves.
The peak of curve C marks the discharge that is
most effective in transporting sediment.
Source: Wolman and Miller (1960).
Although the assumption that the chan-
nel-forming flow has a recurrence inter-
val of 1 to 3 years is sufficient for
reconnaissance-level studies, it should
not be used for design until verified
through inspection of reference reaches,
data collection, and analysis. This is es-
pecially true in highly modified streams
such as in urban or mined areas, as well
as ephemeral streams in arid and semi-
arid areas.
Effective Discharge
The effective discharge is defined as the
increment of discharge that transports
the largest fraction of the sediment load
over a period of years (Andrews 1980).
The effective discharge incorporates the
principle prescribed by Wolman and
Miller (1960) that the channel-forming
discharge is a function of both the mag-
nitude of the event and its frequency of
occurrence. An advantage of using the
effective discharge is that it is a calcu-
lated rather than field-determined
value. The effective discharge is calcu-
lated by numerically integrating the
flow duration curve (A) and the sedi-
ment transport rating curve (B). A
graphical representation of the relation-
ship between sediment transport, fre-
quency of the transport, and the
effective discharge is shown in Figure
7.5. The peak of curve C marks the dis-
charge that is most effective in trans-
porting sediment and, therefore, does
the most work in forming the channel.
For stable alluvial streams, effective dis-
charge has been shown to be highly
correlated with bankfull discharge. Of
the various discharges related to chan-
nel morphology (i.e., dominant, bank-
full, and effective discharges), effective
discharge is the only one that can be
computed directly. The effective dis-
charge has morphological significance
since it is the discharge that transports
the bulk of the sediment.
The effective discharge represents the
single flow increment that is responsi-
ble for transporting the most sediment
over some time period. However, there
is a range of flows on either side of the
effective discharge that also carry a sig-
nificant portion of the total annual sed-
iment load.
Biedenharn and Thorne (1994) used
a graphical relationship between the
Hydrologic Processes
7-13
-------
cumulative percentage of sediment
transported and the water discharge
to define a range of effective discharges
responsible for the majority of the sedi-
ment transport on the Lower Mississippi
River. They found that approximately
70 percent of the total sediment was
moved in a range of flows between
500,000 cfs and 1,200,000 cfs, which
corresponds to the flow that is equaled
or exceeded 40 percent of the time and
3 percent of the time, respectively.
Thorne et al. (1996) used a similar ap-
proach to define the range of effective
discharges on the Brahmaputra River.
A standard procedure should be used
for the determination of the effective
discharge to ensure that the results for
different sites can be compared. To be
practical, it must either be based on
readily available gauging station data or
require only limited additional infor-
mation and computational procedures.
The basic components required for cal-
culation of effective discharge are (1)
flow duration data and (2) sediment
load as a function of water discharge.
The method most commonly adopted
for determining the effective discharge
is to calculate the total bed material
sediment load (tons) transported by
each flow increment over a period of
time by multiplying the frequency of
occurrence for the flow increment
(number of days) by the sediment load
(tons/day) transported by that flow
level. The flow increment with the
largest product is the effective discharge.
Although this approach has the merit of
simplicity, the accuracy of the estimate
of the effective discharge is clearly de-
pendent on the calculation procedure
adopted.
Values of mean daily discharges are
usually used to compute the flow dura-
tion curve, as discussed above and pre-
sented in Figure 7.1. However, on flashy
Design Discharge and
Ecological Function
Although a channel-forming or domi-
nant discharge is important for design,
it is often not sufficient for channel
restoration initiatives. An assessment
of a wider range of discharges might
be necessary to ensure that the func-
tional objectives of the project are met
For example, a restoration initiative
targeting low-flow habitat conditions
must consider the physical conditions
in the channel during low flows.
streams, mean daily values can underes-
timate the influence of the high flows,
and, therefore, it might be necessary to
reduce the discharge averaging period
from 24 hours (mean daily) to 1 hour,
or perhaps 15 minutes.
A sediment rating curve must be devel-
oped to determine the effective dis-
charge. (See the Sediment Yield and
Delivery section in Chapter 8 for more
details.) The bed material load should
be used in the calculation of the effec-
tive discharge. This sediment load can
be determined from measured data or
computed using an appropriate sedi-
ment transport equation. If measured
suspended sediment data are used, the
wash load should be subtracted and
only the suspended bed material por-
tion of the suspended load used. If the
bed load is a significant portion of the
load, it should be calculated using an
appropriate sediment transport func-
tion and added to the suspended bed
material load to provide an estimate of
the total bed material load. If bed load
measurements are available, these data
can be used.
7-14
Chapter 7: Analysis of Corridor Condition
-------
Determination of effective discharge
using flow and sediment data is further
discussed by Wolman and Miller
(1960) and Carling (1988).
Determining Channel-Forming
Discharge from Other Watershed
Variables
When neither time nor resources permit
field determination of bankfull dis-
charge or data are unavailable to calcu-
late the effective discharge, indirect
methods based on regional hydrologic
analysis may be used (Ponce 1989). In
its simplest form, regional analysis en-
tails regression techniques to develop
empirical relationships applicable to
homogeneous hydrologic regions. For
example, some workers have used wa-
tershed areas as surrogates for discharge
(Brookes 1987, Madej 1982, Newbury
and Gaboury 1993). Regional relation-
ships of drainage area with bankfull
discharge can provide good starting
points for selecting the channel-forming
discharge.
Within hydrologically homogeneous re-
gions where runoff varies with con-
tributing area, runoff is proportional to
watershed drainage area. Dunne and
Leopold (1978) and Leopold (1994) de-
veloped average curves relating bankfull
discharge to drainage area for widely
separated regions of the United States.
For example, relationships between
bankfull discharge and drainage area for
Brandywine Creek in Pennsylvania and
the upper Green River basin in
Wyoming are shown in the Figure 7.6.
Two important points are immediately
apparent from Figure 7.6. First, humid
regions that have sustained, widely dis-
tributed storms yield higher bankfull
discharges per unit of drainage area
than semiarid regions where storms of
high intensity are usually localized. Sec-
ond, bankfull discharge is correlated
with drainage area, and the general rela-
Regional Relationship Between
Bankfull and Mean Annual Discharge
Because the mean annual flow for each stream gauge
operated by the USGS is readily available, it is useful to
establish regional relationships between bankfull and
mean annual discharges so that one can be estimated
whenever the other is available. This information can be
compared to the bankfull discharge estimated for any
given ungauged site within a U.S. region. The user is
cautioned, however, that regional curve values
have a high degree of error and can vary signifi-
cantly for specific sites or reaches to be restored.
tionship can be represented by func-
tions of the form:
Qbf = aAb
where Qbf is the bankfull discharge in
cfs, A is the drainage area in square
miles, and a and b are regression coeffi-
cients and exponents given in Table 7.1.
Establishing similar parametric relation-
ships for other rivers of interest is useful
because the upstream area draining into
a stream corridor can be easily deter-
mined from either maps or digital ter-
rain analysis tools. Once the area is
determined, an estimate of the expected
bankfull discharge for the corridor can
be made from the above equation.
Mean Annual Flow
Another frequently used surrogate for
channel-forming discharge in empirical
regression equations is the mean annual
flow. The mean annual flow, Qm, is
equivalent to the constant discharge
that would yield the same volume of
water in a water year as the sum of all
continuously measured discharges. Just
as in the case of bankfull discharge, Qm
varies proportionally with drainage area
within hydrologically homogeneous
Hydrologic Processes
7-15
-------
100
Drainage Area (square miles)
1000
Figure 7.6: Regional relationships for bankfull and mean annual discharge as a function of
drainage area. The mean annual flow is normally less than the bankfull flow.
Source: Dunne and Leopold 1978.
Table 7.1: Functional parameters used in
regional estimates of bankfull discharge.
In column a are regression coefficients
and in column b are exponents that can
be used in the bankfull discharge equation.
Source: Dunne and Leopold 1978.
River Basin
Southeastern PA
Upper Salmon River, ID
Upper Green River, WY
San Francisco Bay Region, CA
Qbf = aA"
61 0.82
36 0.68
28 0.69
53 0.93
basins. Given that both Qbf and Qm ex-
hibit a similar functional dependence
on A, a consistent proportionality is to
be expected between these discharge
measures within the same region. In
fact, Leopold (1994) gives the following
average values of the ratio Qbf/Qm for
three widely separated regions of the
United States: 29.4 for 21 stations in
the Coast Range of California, 7.1 for
20 stations in the Front Range of Col-
orado, and 8.3 for 13 stations in the
Eastern United States.
7-16
Chapter 7: Analysis of Corridor Condition
-------
Stage vs. Discharge
Relationships
Surveys of stream channel cross sections
are useful for analyzing channel form,
function, and processes. Use of survey
data to construct relationships among
streamflow, channel geometry, and vari-
ous hydraulic characteristics provides
information that serves a variety of ap-
plications. Although stage-discharge
curves often can be computed from
such cross section data, users should be
cautioned to verify their computations
with direct discharge measurements
whenever possible.
Information on stream channel geome-
try and hydraulic characteristics is use-
ful for channel design, riparian area
restoration, and instream structure
placement. Ideally, once a channel-
forming discharge is defined, the chan-
nel is designed to contain that flow and
higher flows are allowed to spread over
the floodplain. Such periodic flooding
is extremely important for the forma-
tion of channel macrofeatures, such as
point bars and meander bends, and for
establishing certain kinds of riparian
vegetation. A cross section analysis also
may help in optimal design and place-
ment of items such as culverts and fish
habitat structures.
Additionally, knowledge of the relation-
ships between discharge and channel
geometry and hydraulics is useful for re-
constructing the conditions associated
with a particular flow rate. For example,
in many channel stability analyses, it is
customary to relate movement of bed
materials to some measure of stream
power or average bed shear stress. If the
relationships between discharge and
certain hydraulic variables (e.g., mean
depth and water surface slope) are
known, it is possible to estimate stream
power and average bed shear as a func-
tion of discharge. A cross section analy-
sis therefore makes it possible to
estimate conditions of substrate move-
ment at various levels of streamflow.
Continuity Equation
Discharge at a cross section is com-
puted using the simplified form of the
continuity equation:
Q = AV
where:
Q = discharge
A = cross sectional area of the
flow
V = average velocity in the down-
stream direction
Computing the cross-sectional area is a
geometry problem. The area of interest
is bounded by the channel cross section
and the water surface elevation (stage)
(Figure 7.7). In addition to cross-
sectional area, the top width, wetted
perimeter, mean depth, and hydraulic
radius are computed for selected stages
(Figure 7.7).
Uniform flow equations may be used
for estimating mean velocity as a
function of cross section hydraulic
parameters.
Manning's Equation
Manning's equation was developed for
conditions of uniform flow in which
the water surface profile and energy
grade line are parallel to the streambed,
and the area, hydraulic radius, and aver-
age depth remain constant throughout
the reach. The energy grade line is a
theoretical line whose elevation above
the streambed is the sum of the water
surface elevation and a term that repre-
sents the kinetic energy of the flow
(Chow 1959). The slope of the energy
grade line represents the rate at which
energy is dissipated through turbulence
and boundary friction. When the water
surface slope and the energy grade line
Hydrologic Processes
7-17
-------
Manning's equation for mean velocity,
V (in feet per second or meters per sec-
ond), is given as:
area
mean depth =topwidth
hydraulic radius = wetted
Figure 7.7: Hydraulic parameters. Streams have
specific cross-sectional and longitudinal profile
characteristics.
parallel the streambed, the slope of the
energy grade line is assumed to equal
the water surface slope. When the slope
of the energy grade line is known, vari-
ous resistance formulas allow comput-
ing mean cross-sectional velocity.
The importance of Manning's equation
in stream restoration is that it provides
the basis for computing differences in
flow velocities and elevations due to
differences in hydraulic roughness.
Note that the flow characteristics can be
altered to meet the goals of the restora-
tion either by direct intervention or by
changing the vegetation and roughness
of the stream. Manning's equation is
also useful in determining bankfull dis-
charge for bankfull stage.
Manning's equation is also used to cal-
culate energy losses in natural channels
with gradually varied flow. In this case,
calculations proceed from one cross sec-
tion to the next, and unique hydraulic
parameters are calculated at each cross
section. Computer models, such as
HEC-2, perform these calculations and
are widely used analytical tools.
V = - R2/3S1/2
n
where:
k = 1.486 for English units (1 for metric
units)
n = Manning's roughness coefficient
R = hydraulic radius (feet or meters)
S = energy slope (water surface slope).
Manning's roughness coefficient may be
thought of as an index of the features of
channel roughness that contribute to
the dissipation of stream energy. Table
7.2 shows a range of n values for vari-
ous boundary materials and conditions.
Two methods are presented for estimat-
ing Manning's roughness coefficient for
natural channels:
Direct solution of Manning's equa-
tion for n.
Comparison with computed n values
for other channels.
Each method has its own limitations
and advantages.
Direct Solution for Determining
Manning's n
Even slightly nonuniform flow can be
difficult to find in natural channels. The
method of direct solution for Man-
ning's n does not require perfectly uni-
form flow. Manning n values are
computed for a reach in which multiple
cross sections, water surface elevations,
and at least one discharge have been
measured. A series of water surface pro-
files are then computed with different n
values, and the computed profile that
matches the measured profile is
deemed to have an n value that most
nearly represents the roughness of that
stream reach at the specific discharge.
7-18
Chapter 7: Analysis of Corridor Condition
-------
Table 7.2: Manning roughness coefficients for various boundaries.
Source: Ven te Chow 1964.
Boundary
Smooth concrete
Ordinary concrete lining
Vitrified clay
Shot concrete, untroweled, and earth channels in best condition
Straight unlined earth canals in good condition
Rivers and earth canals in fair conditionsome growth
Winding natural streams and canals in poor conditionconsiderable
moss growth
Mountain streams with rocky beds and rivers with variable sections and
some vegetation along banks
Alluvial channels, sand bed, no vegetation
1. Lower regime
Ripples
Dunes
Manning Roughness, n Coefficient
0.012
0.013
0.015
0.017
0.020
0.025
0.035
0.040-0.050
2. Washed-out dunes or transition
3. Upper regime
Plane bed
Standing waves
Antidunes
0.017-0.028
0.018-0.035
0.014-0.024
0.011-0.015
0.012-0.016
0.012-0.020
Using Manning's n Measured at
Other Channels
The second method for estimating n
values involves comparing the reach to
a similar reach for which Manning's n
has already been computed. This proce-
dure is probably the quickest and most
commonly used for estimating Man-
ning's n. It usually involves using values
from a table or comparing the study
reach with photographs of natural
channels. Tables of Manning's n values
for a variety of natural and artificial
channels are common in the literature
on hydrology (Chow 1959, Van Hav-
eren 1986) (Table 7.2). Photographs
of stream reaches with computed n
values have been compiled by Chow
(1959) and Barnes (1967). Estimates
should be made for several stages, and
the relationship between n and stage
should be defined for the range of flows
of interest.
When the roughness coefficient is esti-
mated from table values, the chosen n
value (nj is considered a base value
that may need to be adjusted for addi-
tional resistance features. Several publi-
cations provide procedures for adjusting
base values of n to account for channel
irregularities, vegetation, obstructions,
and sinuosity (Chow 1959, Benson and
Dalrymple 1967, Arcement and Schnei-
der 1984, Parsons and Hudson 1985).
The most common procedure uses the
following formula, proposed by Cowan
(1959) to estimate the value of n:
11 = K + n, + n2 + ^ + nJ m
where
nb = base value of n for a straight,
uniform, smooth channel in
natural materials
n: = correction for the effect of sur-
face irregularities
Hydrologic Processes
7-19
-------
Uniform Flow
Under conditions of constant width, depth, area,
and velocity, the water surface slope and energy
grade line approach the slope of the streambed,
producing a condition known as "uniform flow."
One feature of uniform flow is that the streamlines
are parallel and straight (Roberson and Crowe
1996). Perfectly uniform flow is rarely realized in
natural channels, but the condition is approached
in some reaches where the geometry of the chan-
nel cross section is relatively constant throughout
the reach.
Conditions that tend to disrupt uniform flow include
bends in the stream course; changes in cross-section-
al geometry; obstructions to flow caused by large
(d)
(c)
roughness elements, such as channel bars, large
boulders, and woody debris; or other features that
cause convergence, divergence, acceleration, or
deceleration of flow (Figure 7.8). Resistance equa-
tions may also be used to evaluate these nonuniform
flow conditions (gradually varied flow); however,
energy-transition considerations (backwater calcula-
tions) must then be factored into the analysis. This
requires the use of multiple-transect models (e.g.,
HEC-2 and WSP2; HEC-2 is a water surface profile
computer program developed by the U.S. Army
Corps of Engineers, Hydrologic Engineering Center, in
Davis, California; WSP2 is a similar program devel-
oped by the USDA Natural Resources Conservation
Service.)
width constriction
Figure 7.8:
Streamflow
paths for chan-
nels with
constrictions or
obstructions.
(a) Riffle or bar,
Nisqually,
Washington.
Source: J. McShane.
(b) Stream width
restriction.
(c) Sweeper log.
(d) Stream lines
through a reach.
7-20
Chapter 7: Analysis of Corridor Condition
-------
n2 = correction for variations in cross
section size and shape
n3 = correction for obstructions
n4 = correction for vegetation and
flow conditions
m = correction for degree of channel
meandering
Table 7.3 is taken from Aldridge and
Garrett (1973) and may be used to esti-
mate each of the above correction fac-
tors to produce a final estimated n.
Energy Equation
The energy equation is used to calculate
changes in water-surface elevation be-
tween two relatively similar cross sec-
tions. A simplified version of this
equation is:
where:
z =
d =
V =
g =
h =
minimum elevation of
streambed
maximum depth of flow
average velocity
acceleration of gravity
energy loss between the two sec-
tions
Subscript 1 indicates that the variable is
at the upstream cross section, and sub-
script 2 indicates that the variable is at
the downstream cross section.
This simplified equation is applicable
when hydraulic conditions between the
two cross sections are relatively similar
(gradually varied flow) and the channel
slope is small (less than 0.18).
Energy losses between the two cross sec-
tions occur due to channel boundary
roughness and other factors described
above. These roughnesses may be repre-
sented by a Manning's roughness coeffi-
cient, n, and then energy losses can be
computed using the Manning equation.
Manning's n in Relation to Channel
Bedforms
Just as Manning's n may vary significantly with changes
in stage (water level), channel irregularities, obstructions,
vegetation, sinuosity, and bed-material size distribution,
n may also vary with bedforms in the channel. The
hydraulics of sand and mobile-bed channels produce
changes in bedforms as the velocity, stream power, and
Froude number increase with discharge. The Froude
number is a dimensionless number that represents the
ratio of inertia I forces to gravitational force. As velocity
and stream power increase, bedforms evolve from rip-
ples to dunes, to washed-out dunes, to plane bed, to
antidunes, to chutes and pools. A stationary plane bed,
ripples, and dunes occur when the Froude number (long
wave equation) is less than 1 (subcritical flow); washed-
out dunes occur at a Froude number equal to 1 (critical
flow); and a plane bed in motion, antidunes, and chutes
and pools occur at a Froude number greater than 1
(supercritical flow). Manning's n attains maximum values
when dune bedforms are present, and minimum values
when ripples and plane bedforms are present (Parsons
and Hudson 1985).
2/312
hc = L [Qn/kAR
where:
L = distance between cross sections
Q = discharge
n = Manning's roughness coefficient
A = channel cross-sectional area
R = hydraulic radius (Area/wetted
perimeter)
k = 1 (SI units)
k = 1.486 (ft-lb-sec units)
Computer models (such as HEC-2 and
others) are available to perform these
calculations for more complex cross-
sectional shapes, including floodplains,
and for cases where roughness varies
laterally across the cross section
(USAGE 1991).
Hydrologic Processes
7-21
-------
Table 7.3: "n" value adjustments.
Source: Aldridge and Garrett (1973).
Channel I n Value I Example
Conditions I Adjustment!' I
Degree of
irregularity (n,)
Variation in
channel cross
section (n2)
Effect of
obstruction (n3)
Amount of
vegetation (n4)
Degree of meandering1
(adjustment values
apply to flow confined
in the channel and do
not apply where
downvalley flow
crosses meanders) (m)
Smooth 0.000
Minor 0.001-0.005
Moderate 0.006-0.010
Severe 0.011-0.020
Gradual 0.000
Alternating 0.001-0.005
occasionally
Alternating 0.010-0.015
frequently
Negligible 0.000-0.004
Minor
0.005-0.015
Appreciable 0.020-0.030
Severe 0.040-0.050
Small 0.002-0.010
Medium 0.010-0.025
Large 0.025-0.050
Very Large 0.050-0.100
Minor
Appreciable
Severe
1.00
1.15
1.30
Compares to the smoothest channel attainable in a given bed material.
Compares to carefully dredged channels in good condition but having
slightly eroded or scoured side slopes.
Compares to dredged channels having moderate to considerable bed
roughness and moderately sloughed or eroded side slopes.
Badly sloughed or scalloped banks of natural streams; badly eroded or
sloughed sides of canals or drainage channels; unshaped, jagged, and
irregular surfaces of channels in rock.
Size and shape of channel cross sections change gradually.
Large and small cross sections alternate occasionally, or the main flow
occasionally shifts from side to side owing to changes in cross-
sectional shape.
Large and small cross sections alternate frequently, or the main flow
frequently shifts from side to side owing to changes in cross-sectional
shape.
A few scattered obstructions, which include debris deposits, stumps,
exposed roots, logs, piers, or isolated boulders, that occupy less than
5 percent of the cross-sectional area.
Obstructions occupy less than 15 percent of the cross-sectional area and
the spacing between obstructions is such that the sphere of influence
around one obstruction does not extend to the sphere of influence
around another obstruction. Smaller adjustments are used for curved
smooth-surfaced objects than are used for sharp-edged angular objects.
Obstructions occupy from 15 to 20 percent of the cross-sectional area
or the space between obstructions is small enough to cause the effects
of several obstructions to be additive, thereby blocking an equivalent
part of a cross section.
Obstructions occupy more than 50 percent of the cross-sectional area
or the space between obstructions is small enough to cause turbulence
across most of the cross section.
Dense growths of flexible turf grass, such as Bermuda, or weeds
growing where the average depth of flow is at least two times the
height of the vegetation; supple tree seedlings such as willow,
cottonwood, arrowweed, or saltcedar growing where the average
depth of flow is at least three times the height of the vegetation.
Turf grass growing where the average depth of flow is from one to
two times the height of the vegetation; moderately dense stemmy
grass, weeds, or tree seedlings growing where the average depth of
the flow is from two to three times the height of the vegetation;
brushy, moderately dense vegetation, similar to 1-to 2-year-old willow
trees in the dormant season, growing along the banks and no
significant vegetation along the channel bottoms where the hydraulic
radius exceeds 2 feet.
Turf grass growing where the average depth of flow is about equal to
the height of vegetation; 8- to 10-year-old willow or cottonwood trees
intergrown with some weeds and brush (none of the vegetation in
foliage) where the hydraulic radius exceeds 2 feet; bushy willows
about 1 year old intergrown with some weeds along side slopes (all
vegetation in full foliage) and no significant vegetation along channel
bottoms where the hydraulic radius is greater than 2 feet.
Turf grass growing where the average depth of flow is less than half
the height of the vegetation; bushy willow trees about 1 year old
intergrown with weeds along side slopes (all vegetation in full foliage)
or dense cattails growing along channel bottom; trees intergrown
with weeds and brush (all vegetation in full foliage).
Ratio of the channel length to valley length is 1.0 to 1.2.
Ratio of the channel length to valley length is 1.2 to 1.5.
Ratio of the channel length to valley length is greater than 1.5.
1 Adjustments for degree of irregularity, variations in cross section, effect of obstructions, and vegetation are added to the base n value before multiplying by the
adjustment for meander.
7-22
Chapter 7: Analysis of Corridor Condition
-------
Backwater Effects
Straight channel reaches with perfectly uniform flow are rare in nature and, in most
cases, may only be approached to varying degrees. If a reach with constant cross-sec-
tional area and shape is not available, a slightly contracting reach is acceptable, provid-
ed there is no significant backwater effect from the constriction. Backwater occurs
where the stage vs. discharge relationship is controlled by the geometry downstream of
the area of interest (e.g., a high riffle controls conditions in the upstream pool at low
flow). Manning's equation assumes uniform flow conditions. Manning's equation used
with a single cross section, therefore, will not produce an accurate stage vs. discharge
relationship in backwater areas. In addition, expanding reaches also should be avoided
since there are additional energy losses associated with channel expansions. When no
channel reaches are available that meet or approach the condition of uniform flow, it
might be necessary to use multitransect models (e.g., HEC-2) to analyze cross section
hydraulics. If there are elevation restrictions corresponding to given flows (e.g., flood
control requirements), the water surface profile for the entire reach is needed and use
of a multitransect (backwater) model is required.
Analyzing Composite and
Compound Cross Sections
Natural channel cross sections are rarely
perfectly uniform, and it may be neces-
sary to analyze hydraulics for very irreg-
ular cross sections (compound
channel). Streams frequently have over-
flow channels on one or both sides that
carry water only during unusually high
flows. Overflow channels and overbank
areas, which may also carry out-of-bank
flows at various flood stages, usually
have hydraulic properties significantly
different from those of the main chan-
nel. These areas are usually treated as
separate subchannels, and the discharge
computed for each of these subsections
is added to the main channel to com-
pute total discharge. This procedure ig-
nores lateral momentum losses, which
could cause n values to be underesti-
mated.
A composite cross section has rough-
ness that varies laterally across the sec-
tion, but the mean velocity can still be
computed by a uniform flow equation
without subdividing the section. For ex-
ample, a stream may have heavily vege-
tated banks, a coarse cobble bed at its
lowest elevations, and a sand bar vege-
tated with small annual willow sprouts.
A standard hydraulics text or reference
(such as Chow 1959, Henderson 1986,
USAGE 1991, etc.) should be consulted
for methods of computing a composite
n value for varying conditions across a
section and for varying depths of flow.
Reach Selection
The intended use of the cross section
analysis plays a large role in locating
the reach and cross sections. Cross sec-
tions can be located in either a short
critical reach where hydraulic character-
Hydrologic Processes
7-23
-------
istics change or in a reach that is con-
sidered representative of some larger
area. The reach most sensitive to change
or most likely to meet (or fail to meet)
some important condition may be con-
sidered a critical reach. A representative
reach typifies a definable extent of the
channel system and is used to describe
that portion of the system (Parsons and
Hudson 1985).
Once a reach has been selected, the
channel cross sections should be mea-
sured at locations considered most
suitable for meeting the uniform flow
requirements of Manning's equation.
The uniform flow requirement is ap-
proached by siting cross sections where
channel width, depth, and cross-
sectional flow area remain relatively
constant within the reach, and the
water surface slope and energy grade
line approach the slope of the stream-
bed. For this reason, marked changes in
channel geometry and discontinuities
in the flow (steps, falls, and hydraulic
jumps) should be avoided. Generally,
sections should be located where it
appears the streamlines are parallel to
the bank and each other within the se-
lected reach. If uniform flow conditions
cannot be met and backwater computa-
tions are required, defining cross sec-
tions located at changes in channel
geometry is essential.
Field Procedures
The basic information to be collected
in the reach selected for analysis is a
survey of the channel cross sections
and water surface slope, a measure-
ment of bed-material particle size
distribution, and a discharge measure-
ment. The U.S. Forest Service has pro-
duced an illustrated guide to field
techniques for stream channel refer-
ence sites (Harrelson et al. 1994) that
is a good reference for conducting field
surveys.
Standard Step Backwater
Computation
Many computer programs (e.g., HEC-2)
are available to compute water surface
profiles. The standard step method of
Chow (1959, p. 265) can be used to
determine the water surface elevation
(depth) at the upstream end of the reach
by iterative approximations. This method
uses trial water surface elevations to
determine the elevation that satisfies the
energy and Manning equations written
for the end sections of the reach. In
using this method, cross sections should
be selected so that velocities increase or
decrease continuously throughout the
reach (USACE 1991).
Survey of Cross Section and
Water Surface Slope
The cross section is established perpen-
dicular to the flow line, and the points
across the section are surveyed relative
to a known or arbitrarily established
benchmark elevation. The distance/ele-
vation paired data associated with each
point on the section may be obtained
by sag tape, rod-and-level survey, hydro-
graphic surveys, or other methods.
Water surface slope is also required for
a cross section analysis. The survey of
water surface slope is somewhat more
complicated than the cross section sur-
vey in that the slope of the water sur-
face at the location of the section (e.g.,
pool, run, or riffle) must be distin-
guished from the more constant slope
of the entire reach. (See Grant et al.
1990 for a detailed discussion on recog-
nition and characteristics of channel
7-24
Chapter 7: Analysis of Corridor Condition
-------
units.) Water surface slope in individual
channel reaches may vary significantly
with changes in stage and discharge.
For this reason, when water surface
slopes are surveyed in the field, the
low-water slope may be approximated
by the change in elevation over the in-
dividual channel unit where the cross
section is located, approximately 1 to 5
channel widths in length, while the
high-water slope is obtained by mea-
suring the change in elevation over a
much longer reach of channel, usually
at least 15 to 20 channel widths in
length.
Bed Material Particle Size Distribution
Computing mean velocity with resis-
tance equations based on relative
roughness, such as the ones suggested
byThorne and Zevenbergen (1985), re-
quires an evaluation of the particle size
distribution of the bed material of the
stream. For streams with no significant
channel armor and bed material finer
than medium gravel, bed material sam-
plers developed by the Federal Inter-
agency Sedimentation Project (FISP
1986) may be used to obtain a repre-
sentative sample of the streambed,
which is then passed through a set of
standard sieves to determine percent
by weight of particles of various sizes.
The cumulative percent of material
finer than a given size may then be
determined.
Particle size data are usually reported
in terms of d., where i represents some
nominal percentile of the distribution
and d. represents the particle size, usu-
ally expressed in millimeters, at which
i percent of the total sample by weight
is finer. For example, 84 percent of the
total sample would be finer than the
d84 particle size. For additional guidance
on bed material sampling in sand-bed
streams, refer to Ashmore et al. (1988).
For estimating velocity in steep moun-
tain rivers with substrate much coarser
than the medium-gravel limitation of
FISP samplers, a pebble count, in which
at least 100 bed material particles are
manually collected from the streambed
and measured, is used to measure sur-
face particle size (Wolman 1954). At
each sample point along a cross section,
a particle is retrieved from the bed, and
the intermediate axis (not the longest
or shortest axis) is measured. The mea-
surements are tabulated as to number
of particles occurring within predeter-
mined size intervals, and the percentage
of the total number in each interval is
then determined. Again, the percentage
in each interval is accumulated to give a
particle size distribution, and the parti-
cle size data are reported as described
above. Additional guidance for bed ma-
terial sampling in coarse-bed streams is
provided in Yuzyk (1986). If an armor
layer or pavement is present, standard
techniques may be employed to charac-
terize bed sediments, as described by
Hey and Thorne (1986).
Discharge Measurement
If several discharge measurements can
be made over a wide range of flows,
relationships among stage, discharge,
and other hydraulic parameters may be
developed directly. If only one dis-
charge measurement is obtained, it
likely will occur during low water and
will be useful for defining the lower
end of the rating table. If two measure-
ments can be made, it is desirable to
have a low-water measurement and a
high-water measurement to define both
ends of the rating table and to establish
the relationship between Manning's n
and stage. If high water cannot be mea-
sured directly, it may be necessary to es-
timate the high-water n (see the
discussion earlier in the chapter).
Hydrologic Processes
7-25
-------
The Bureau of Reclamation Water Mea-
surement Manual (USDI-BOR 1997) is
an excellent source of information for
measuring channel and stream dis-
charge (Figure 7.9). Buchanan and
Somers (1969) and Rantz et al. (1982)
also provide in-depth discussions of
discharge measurement techniques.
When equipment is functioning prop-
erly and standard procedures are fol-
lowed correctly, it is possible to
measure streamflow to within 5 percent
of the true value. The USGS considers
a "good" measurement of discharge to
account for plus or minus 5 percent
and an "excellent" discharge measure-
ment to be within plus or minus 3 per-
cent of the true value.
Figure 7.9: Station
measuring discharge.
Permanent stations
provide measure-
ments for a wide
range of flow, but
the necessary mea-
surements can be
made in other ways.
Source: C. Zabawa.
7.B Geomorphic Processes
In planning a project along a river or
stream, awareness of the fundamentals
of fluvial geomorphology and channel
processes allows the investigator to see
the relationship between form and
process in the landscape. The detailed
study of the fluvial geomorphic
processes in a channel system is often
referred to as a geomorphic assessment.
The geomorphic assessment provides
the process-based framework to define
past and present watershed dynamics,
develop integrated solutions, and assess
the consequences of restoration activi-
ties. A geomorphic assessment generally
includes data collection, field investiga-
tions, and channel stability assessments.
It forms the foundation for analysis and
design and is therefore an essential first
step in the design process, whether
planning the treatment of a single reach
or attempting to develop a comprehen-
sive plan for an entire watershed.
Stream Classification
The use of any stream classification sys-
tem is an attempt to simplify what are
complex relationships between streams
and their watersheds.
Although classification can be used as a
communications tool and as part of the
overall restoration planning process, the
use of a classification system is not re-
quired to assess, analyze, and design
stream restoration initiatives. The de-
sign of a restoration does, however, re-
quire site-specific engineering analyses
and biological criteria, which are cov-
ered in more detail in Chapter 8.
Restoration designs range from simple
to complex, depending on whether "no
action," only management techniques,
direct manipulation, or combinations
of these approaches are used. Complete
stream corridor restoration designs re-
quire an interdisciplinary approach as
7-26
Chapter 7: Analysis of Corridor Condition
-------
discussed in Chapter 4. A poorly de-
signed restoration might be difficult to
repair and can lead to more extensive
problems.
More recent attempts to develop a com-
prehensive stream classification system
have focused on morphological forms
and processes of channels and valley
bottoms, and drainage networks. Classi-
fication systems might be categorized as
systems based on sediment transport
processes and systems based on channel
response to perturbation.
Stream classification methods are re-
lated to fundamental variables and
processes that form streams. Streams are
classified as either alluvial or non-
alluvial. An alluvial stream is free to
adjust its dimensions, such as width,
depth, and slope, in response to changes
in watershed sediment discharge. The
bed and banks of an alluvial stream are
composed of material transported by
the river under present flow conditions.
Conversely, a non-alluvial river, like a
bedrock-controlled channel, is not free
to adjust. Other conditions, such as a
high mountain stream flowing in very
coarse glacially deposited materials or
streams which are significantly con-
trolled by fallen timber, would suggest
a non-alluvial system.
Streams may also be classified as either
perennial, intermittent, or ephemeral,
as discussed in Chapter 1. A perennial
stream is one that has flow at all times.
An intermittent stream has the potential
for continued flow, but at times the en-
tire flow is absorbed by the bed mater-
ial. This may be seasonal in nature.
An ephemeral stream has flow only fol-
lowing a rainfall event. When carrying
flow, intermittent and ephemeral
streams both have characteristics very
similar to those of perennial streams.
Advantages of Stream
Classification Systems
The following are some advantages of
stream classification systems:
Classification systems promote com-
munication among persons trained
in different resource disciplines.
They also enable extrapolation of
inventory data collected on a few
channels of each stream class to a
much larger number of channels over
a broader geographical area.
Classification helps the restoration
practitioner consider the landscape
context and determine the expected
range of variability for parameters
related to channel size, shape, and
pattern and composition of bed and
bank materials.
Stream classification also enables the
practitioner to interpret the channel-
forming or dominant processes active
at the site, providing a base on which
to begin the process of designing
restoration.
Classified reference reaches can be
used as the stable or desired form of
the restoration.
A classification system is also very
useful in providing an important
cross-check to verify if the selected
design values for width/depth ratio,
sinuosity, etc., are within a reason-
able range for the stream type being
restored.
Limitations of Stream
Classification Systems
All stream classification systems have
limitations that are inherent to their ap-
proaches, data requirements, and range
of applicabilities. They should be used
cautiously and only for establishing
some of the baseline conditions on
Geomorphic Processes
7-27
-------
which to base initial restoration plan-
ning. Standard design techniques
should never be replaced by stream
classification alone.
Some limitations of classification sys-
tems are as follows:
Determination of bankfull or channel-
forming flow depth may be difficult
or inaccurate. Field indicators are
often subtle or missing and are not
valid if the stream is not stable and
alluvial.
The dynamic condition of the stream
is not indicated in most classification
systems. The knowledge of whether
the stream is stable, aggrading, or
degrading or is approaching a critical
geomorphic threshold is important
for a successful restoration initiative.
River response to a perturbation or
restoration action is normally not
determined from the classification
system alone.
Biological health of a stream is usual-
ly not directly determined through a
stream classification system.
A classification system alone should
not be used for determining the type,
location, and purpose of restoration
activities. These are determined
through the planning steps in Part II
and the design process in Chapter 8.
When the results of stream classifica-
tion will be used for planning or de-
sign, the field data collection should be
performed or directed by persons with
experience and training in hydrology,
hydraulics, terrestrial and aquatic ecol-
ogy, sediment transport, and river me-
chanics. Field data collected by
personnel with only limited formal
training may not be reliable, particu-
larly in the field determination of bank-
full indicators and the assessment of
channel instability trends.
Stream Classification Systems
Stream Order
Designation of stream order, using the
Strahler (1957) method, described in
Chapter 1, is dependent on the scale of
maps used to identify first-order
streams. It is difficult to make direct
comparisons of the morphological
characteristics of two river basins ob-
tained from topographic maps of differ-
ent scales. However, the basic
morphological relationships defined by
Horton (1945) and Yang (1971) are
valid for a given river basin regardless
of maps used, as shown in the case
study of the Rogue River Basin (Yang
and Stall 1971, 1973).
Horton (1945) developed some basic
empirical stream morphology relations,
i.e., Horton's law of stream order,
stream slope, and stream length. These
show that the relationships between
stream order, average stream length,
and slope are straight lines on semilog
paper.
Yang (1971) derived his theory of aver-
age stream fall based on an analogy
with thermodynamic principles. The
theory states that the ratio of average fall
(change in bed elevation) between any
two stream orders in a given river basin
is unity. These theoretical results were
supported by data from 14 river basins
in the United States with an average fall
ratio of 0.995. The Rogue River basin
data were used by Yang and Stall
(1973) to demonstrate the relationships
between average stream length, slope,
fall, and number of streams.
Stream order is used in the River Contin-
uum Concept (Vannote et al. 1980),
described in Chapter 1, to distinguish
different levels of biological activity.
However, stream order is of little help
to planners and designers looking for
clues to restore hydrologic and geomor-
phic functions to stream corridors.
7-28
Chapter 7: Analysis of Corridor Condition
-------
Schumm
Other classification schemes combine
morphological criteria with dominant
modes of sediment transport. Schumm
(1977) identified straight, meandering,
and braided channels and related both
channel pattern and stability to modes
of sediment transport (Figure 7.10).
Schumm recognized relatively stable
straight and meandering channels, with
predominantly suspended sediment
load and cohesive bank materials. On
the other end of the spectrum are rela-
tively unstable braided streams charac-
terized by predominantly bedload
sediment transport and wide, sandy
channels with noncohesive bank mate-
rials. The intermediate condition is gen-
erally represented by meandering
mixed-load channels.
Montgomery and Buffington
Schumm's classification system primar-
ily applies to alluvial channels; Mont-
gomery and Buffington (1993) have
proposed a similar classification system
for alluvial, colluvial, and bedrock
streams in the Pacific Northwest that
addresses channel response to sediment
inputs throughout the drainage net-
work. Montgomery and Buffington rec-
ognize six classes of alluvial
channelscascade, step-pool, plane-
bed, riffle-pool, regime, and braided
(Figure 7.11).
The stream types are differentiated on
the basis of channel response to sedi-
ment inputs, with steeper channels
(cascade and step-pool) maintaining
their morphology while transmitting
increased sediment loads, and low-
gradient channels (regime and pool-
riffle) responding to increased sediment
through morphological adjustments. In
general, steep channels act as sediment-
delivery conduits connecting zones of
sediment production with low-gradient
response channels.
Rosgen Stream Classification System
One comprehensive stream classifica-
tion system in common use is based on
morphological characteristics described
by Rosgen (1996) (Figure 7.12). The
Rosgen system uses six morphological
measurements for classifying a stream
reachentrenchment, width/depth
ratio, sinuosity, number of channels,
slope, and bedmaterial particle size.
These criteria are used to define eight
major stream classes with about 100
individual stream types.
Rosgen uses the bankfull discharge
to represent the stream-forming dis-
charge or channel-forming flow. Bank-
full discharge is needed to use this
classification system because all of the
morphological relationships are related
to this flow condition: width and depth
of flow are measured at the bankfull
elevation, for example.
Except for entrenchment and
width/depth ratio (both of which de-
pend on a determination of bankfull
depth), the parameters used are rela-
tively straightforward measurements.
The problems in determining bankfull
depth were discussed earlier in Chapter
1. The width/depth ratio is taken at
bankfull stage and is the ratio of top
width to mean depth for the bankfull
channel. Sinuosity is the ratio of stream
length to valley length or, alternatively,
valley slope to stream slope. The bed
material particle size used in the classi-
fication is the dominant bed surface
particle size, determined in the field by
a pebble-count procedure (Wolman
1954) or as modified for sand and
smaller sizes. Stream slope is measured
over a channel reach of at least 20
widths in length.
Entrenchment describes the relation-
ship between a stream and its valley
and is defined as the vertical contain-
ment of the stream and the degree to
Geomorphic Processes
7-29
-------
Suspended Load
Channel Type
Mixed Load
Bed Load
gi
'ro
II
£
re
c
(0
01
T3
g
ill
1 "
00 Ol O)
channel boundary
flow
bars
01
X
-Q
ro
_ro
0)
High ^B Relative Stability
(3%>) low r bed load/total load ratio
small sediment size
small sediment load
low 4" flow velocity
low stream power
Low
Figure 7.10: Classification of alluvial channels.
Schumm's classification system relates channel
stability to kind of sediment load and channel
type.
Source: Schumm, The Fluvial System. © 1977.
Reprinted by permission of John Wiley and Sons, Inc.
which it is incised in the valley floor. It
is, therefore, a measure of how accessi-
ble a floodplain is to the stream. The
entrenchment ratio used in the Rosgen
classification system is the flood-prone
width of the valley divided by the bank-
full width of the channel. Flood-prone
width is determined by doubling the
maximum depth in the bankfull chan-
nel and measuring the width of the val-
ley at that elevation. If the flood-prone
width is greater than 2.2 times the
bankfull width, the stream is consid-
ered to be slightly entrenched or con-
fined and the stream has ready access to
its floodplain. A stream is classified as
high (>11%)
large
large
high
high
entrenched if its flood-prone width is
less than 1.4 times the bankfull width.
A sample worksheet for collecting data
and classifying a stream using the Ros-
gen system is shown in Figure 7.13. A
field book for collecting reference reach
information is available (Leopold et al.
1997).
Channel Evolution Models
Conceptual models of channel evolution
describe the sequence of changes a
stream undergoes after certain kinds
of disturbances. The changes can in-
clude increases or decreases in the
width/depth ratio of the channel and
also involve alterations in the flood-
plain. The sequence of changes is some-
what predictable, so it is important that
the current stage of evolution be identi-
fied so appropriate actions can be
planned.
7-30
Chapter 7: Analysis of Corridor Condition
-------
Figure 7.11: Suggested stream classification
system for Pacific Northwest. Included are
classifications for nonalluvial streams.
Source: Montgomery and Buffington 1993.
tolluvia. | Braided | Regime | Poo.-Riffle
^^H Braided
Typical Bed Variable
Material
Bedform Laterally
Pattern oscillary
Reach Type Response
Dominant Bedforms
Roughness (bars,
Elements pools)
Dominant Fluvial,
Sediment bank
Sources failure,
Transport Limited
1 Regime 1 Pool-Riffle 1 Plane-Bed
Sand Gravel Gravel,
cobble
Multi- Laterally None
layered oscillary
Response Response Response
Sinuosity, Bedforms Grains,
bedforms (bars, pools), banks
(dunes, grains, LWD,
ripples, bars) sinuosity,
banks banks
Fluvial, Fluvial, Fluvial,
bank failure, bank failure, bank
inactive inactive failure,
Plane-Bed I Step-Pool I Cascade
Supply Limit
| Bedrock ^^H
ed
| Step-Pool | Cascade 1 Bedrock 1 Colluvial 1
Cobble, Boulder N/A
boulder
Variable
Vertically None Variable
oscillary
Transport Transport Transport Source
Bedforms Grains, Boundaries Grains,
(steps, banks (bed & LWD
pools), banks)
grains, LWD,
banks
Fluvial, Fluvial, Fluvial, Hillslope,
hillslope, hillslope, hillslope, debris
debris flow debris flow debris flow flow
debris flow channel channel, debris flow
debris flows
Sediment Overbank, Overbank, Overbank, Overbank,
Storage bedforms
Elements
bedforms, bedforms, inactive
inactive inactive channel
Bedforms Lee & stoss Bed
sides of flow
obstructions
channel channel
Typical Slope S < 0.03
(m/m)
S < 0.001 0.001
and
0.20
and and
S < 0.08 S < 0.30
Confined Confined Confined Confined
1 to 4 < 1 Variable Variable
7-31
-------
Entrench
Ratio
Width/I
Sinuosity
Channel
Material
Single-Threaded Channels
Entrenched (Ratio: < 1.4)
Low
width/depth ratio
murn
moderate Moderate
to High w/d width/depth ratio
Multiple Channels
Very Low moderate to High very High
width/depth
width/depth width/depth
(>40)
Low Moderate Moderate Moderate
Sinuosity Sinuosity Sinuosity Sinuosity
Very High High
Sinuosity Sinuosity
©
© ©
(
Low
Sinuosity
'
© ©
slope range slope range slope range slope range
>0.10 0.04- 0.02- <0.02 0.02- <0.02 .04- 0.02- <0.02
0.099 0.039 0.039 0.099 0.039
slope range slope range
slope range
0.02- <0.02 .02- .001- <.001 .02- .001- <.001
0.039 0.039 0.02 0.039 0.02
Low
w/d
(<40)
I
Low-Hi
Sinuosity
(1.2-1.5 )
slope
<.005
Schumm et al. (1984), Harvey and Wat-
son (1986), and Simon (1989) have
proposed similar channel evolution
models due to bank collapse based on a
"space-for-time" substitution, whereby
downstream conditions are interpreted
as preceding (in time) the immediate
location of interest and upstream con-
ditions are interpreted as following (in
time) the immediate location of inter-
est. Thus, a reach in the middle of the
watershed that previously looked like
the channel upstream will evolve to
look like the channel downstream.
Downs (1995) reviews a number of
classification schemes for interpreting
channel processes of lateral and vertical
adjustment (i.e., aggradation, degrada-
tion, bend migration, and bar forma-
tion). When these adjustment processes
are placed in a specific order of occur-
rence, a channel evolution model
(GEM) is developed. Although a num-
ber of CEMs have been suggested, two
models (Schumm et al. 1984 and
Figure 7.12: Rosgen's stream channel classifica-
tion system (Level II). This classification system
includes a recognition of specific characteristics
of channel morphology and the relationship
between the stream and its floodplain.
Source: Rosgen 1996. Published by permission of
Wildland Hydrology.
Simon 1989, 1995) have gained wide
acceptance as being generally applicable
for channels with cohesive banks.
Both models begin with a pre-
disturbance condition, in which the
channel is well vegetated and has
frequent interaction with its flood-
plain. Following a perturbation in the
system (e.g., channelization or change
in land use), degradation occurs, usu-
ally as a result of excess stream power
in the disturbed reach. Channel degra-
dation eventually leads to oversteep-
ening of the banks, and when critical
bank heights are exceeded, bank fail-
ures and mass wasting (the episodic
7-32
Chapter 7: Analysis of Corridor Condition
-------
STREAM CLASSIFICATION WORKSHEET
Bankfull Measurements:
Width
Party:
State:
Stream:
Depth
Date:
County:
Lat/Long
W/D
Sinuosity (Stream Length/Valley Length) or (Valley Slope/Channel Slope):
Strm. Length Valley Slope
Valley Length Channel Slope _
SL Ys.
Sinuosity VL Sinuosity Cs
Entrenchment Ratio (Floodprone Width/Bankfull Width):
Floodprone width is water level at 2x maximum depth in bankfull cross-section,
or width of intermediate floodplain (10-50 yr. event)
Bankfull Width Floodprone Width
Entrenchment Ratio
Slight = 2.2+ Moderate + 1.41-2.2 Entrenched = 1.0-1.4
Dominant Channel Soils:
Bed Material Left Bank Right Bank
Description of Soil Profiles (from base of bank to top)
Left:
Right:
Riparian Vegetation:
Left Bank:
% Total Area (Mass) L.
% Total Htw/RootsL_
Right Bank
R
R
Ratio of Actual Bank Height to Bankfull Height
Bank Slope (Horizontal to Vertical): L
STREAM TYPE
Remarks
PEBBLE COUNT Site
Metric
(mm)
<.062
.062-0.25
0.25-.5
.5-1.0
1.0-2.0
2-8
8-16
16-32
32-64
64-128
128-256
256-512
512-1024
1024-2048
2048-4096
English
(inches)
<.002
.002-. 01
.01 -.02
.02-.04
.04-.08
.08-.32
.32-. 63
.63-1.26
1.26-2.51
2.51-5.0
5.0-10.1
10.1-20.2
20.2-40.3
40.3-80.6
80.6-161
Particle
Silt/Clay
Fine Sand
Med Sand
Coarse Sand
Vy Coarse Sand
Fine Gravel
Med Gravel
Coarse Gravel
Vy Coarse Gravel
Small Cobbles
Large Cobbles
Sm Boulders
Med Boulders
Lg Boulders
Vy Lg Boulders
Count
Tot
#
%
Tot
%
Cum
Count
Tot
#
%
Tot
%
Cum
Count
Tot
#
%
Tot
%
Cum
Figure 7.13: Example of stream classification worksheet used with Rosgen methods.
Source: NRCS 1994 (worksheet) and Rosgen 1996 (pebble count). Published by permission of Wildland Hydrology.
Geomorphic Processes
7-33
-------
downslope movement of soil and rock)
lead to channel widening. As channel
widening and mass wasting proceed up-
stream, an aggradation phase follows in
which a new low-flow channel begins
to form in the sediment deposits.
Upper banks may continue to be unsta-
ble at this time. The final stage of evolu-
tion is the development of a channel
within the deposited alluvium with di-
mensions and capacity similar to those
of the predisturbance channel (Downs
1995). The new channel is usually
lower than the predisturbance channel,
and the old floodplain now functions
primarily as a terrace.
Once streambanks become high, either
by downcutting or by sediment deposi-
tion on the floodplain, they begin to
fail due to a combination of erosion at
the base of the banks and mass wasting.
The channel continues to widen until
flow depths do not reach the depths re-
quired to move the sloughed bank ma-
terials. Sloughed materials at the base
of the banks may begin to be colonized
by vegetation. This added roughness
helps increase deposition at the base of
the banks, and a new small-capacity
channel begins to form between the sta-
bilized sediment deposits. The final
stage of channel evolution results in a
new bankfull channel and active flood-
plain at a new lower elevation. The
original floodplain has been aban-
doned due to channel incision or exces-
sive sediment deposition and is now
termed a terrace.
Schumm et al. (1984) applied the basic
concepts of channel evolution to the
problem of unstable channelized
streams in Mississippi. Simon (1989)
built on Schumm's work in a study of
channelized streams in Tennessee.
Simon's CEM consisted of six stages
(Figure 7.14). Both models use the
cross section, longitudinal profile, and
geomorphic processes to distinguish
stages of evolution. Both models were
developed for landscapes dominated by
streams with cohesive banks. However,
the same physical processes of evolu-
tion can occur in streams with nonco-
hesive banks but not necessarily in the
same well-defined stages.
Table 7.4 and Figure 7.15 show the
processes at work in each of Simon's
stages.
Advantages of Channel
Evolution Models
CEMs are useful in stream corridor
restoration in the following ways
(Note: Stages are from Simon's 1989
six-stage CEM):
CEMs help to establish the direction
of current trends in disturbed or con-
structed channels. For example, if a
reach of stream is classified as being
in Stage IV of evolution (Figure
7.14), more stable reaches should
occur downstream and unstable
reaches should occur upstream.
Once downcutting or incision occurs
in a stream (Stage III), the headcut
will advance upstream until it reach-
es a resistant soil layer, the drainage
area becomes too small to generate
erosive runoff, or the slope flattens to
the point that the stream cannot
generate enough energy to downcut.
Stages IV to VI will follow the head-
cut upstream.
CEMs can help to prioritize restora-
tion activities if modification is
planned. By stabilizing a reach of
stream in early Stage III with grade
control measures, the potential
degradation of that reach and
upstream reaches can be prevented.
It also takes less intensive efforts to
successfully restore stream reaches in
Stages V and VI than to restore those
in Stages III and IV
7-34
Chapter 7: Analysis of Corridor Condition
-------
Class I. Sinuous, Premodified
hhc
slumped material
Class V. Aggradation and Widening
h>hc
Class VI. Quasi Equilibrium
h
-------
CEMs can help match solutions to the
problems. Downcutting in Stage III
occurs due to the greater capacity of
the stream created by construction, or
earlier incision, in Stage II. The down-
cutting in Stage III requires treat-
ments such as grade control aimed at
modifying the factors causing the bot-
tom instability. Bank stability prob-
lems are dominant in Stages IV and V,
so the approaches to stabilization
required are different from those for
Stage III. Stages I and VI typically
require only maintenance activities.
Table 7.4: Dominant hillslope and instream
processes, characteristic cross section shape
and bedforms, and condition of vegetation in
the various stages of channel evolution.
Source: Simon 1989.
CEMs can help provide goals or
models for restoration. Reaches of
streams in Stages I and VI are graded
streams, and their profile, form, and
pattern can be used as models for
restoring unstable reaches.
Limitations of Channel Evolution
Models
The chief limitations in using CEMs for
stream restoration are as follows:
Future changes in base level eleva-
tions and watershed water and sedi-
ment yield are not considered when
predicting channel response.
Multiple adjustments by the stream
simultaneously are difficult to pre-
dict.
Dominant Processes
No. I Name
I Premodified
II Constructed
III Degradation
IV Threshold
Hillslope
Aggradation
VI Restabilization
Sediment transport - mild
aggradation; basal erosion
on outside bends;
deposition on inside
bends.
Degradation; basal
erosion on banks.
Degradation; basal
erosion on banks.
Aggradation;
development of
meandering thalweg;
initial deposition of
alternate bars; reworking
of failed material on
lower banks.
Aggradation; further
development of
meandering thalweg;
further deposition of
alternate bars; reworking
of failed material; some
basal erosion on outside
bends deposition of flood-
plain and bank surfaces.
Pop-out
failures.
Slab,
rotational and
pop-out
failures.
Slab,
rotational and
pop-out
failures; low-
angle slides of
previously
failed
material.
Low-angle
slides; some
pop-out
failures near
flow line.
Characteristic Forms
Stable, alternate channel bars;
convex top-bank shape; flow
line high relative to top bank;
channel straight or meandering.
Trapezoidal cross section; linear
bank surfaces; flow line lower
relative to top bank.
Heightening and steepening of
banks; alternate bars eroded;
flow line lower relative to top
bank.
Large scallops and bank retreat;
vertical face and upper-bank
surfaces; failure blocks on
upper bank; some reduction in
bank angles; flow line very low
relative to top bank.
Large scallops and bank retreat;
vertical face, upper bank, and
slough line; flattening of bank
angles; flow line low relative to
top bank; development of new
floodplain.
Stable, alternate channel bars;
convex-short vertical face on
top bank; flattening of bank
angles; development of new
floodplain; flow line high
relative to top bank.
Geobotanical
Evidence
Vegetated banks to
flow line.
Removal of vegetation.
Riparian vegetation
high relative to flow
line and may lean
toward channel.
Riparian vegetation
high relative to flow
line and may lean
toward channel.
Tilted and fallen
riparian vegetation;
reestablishing
vegetation on slough
line; deposition of
material above root
collars of slough line
vegetation.
Reestablishing
vegetation extends up
slough line and upper
bank; deposition of
material above root
collars of slough-line
and upper-bank
vegetation; some
vegetation
establishing on bars.
7-36
Chapter 7: Analysis of Corridor Condition
-------
Applications of Geomorphic
Analysis
Stream classification systems and chan-
nel evolution models may be used to-
gether in resource inventories and
analysis to characterize and group
streams. Although many classification
systems are based on morphological pa-
rameters, and channel evolution models
are based on adjustment processes, the
two approaches to stream characteriza-
tion complement each other. Both indi-
cate the present condition of a stream
reach under investigation, but character-
ization of additional reaches upstream
and downstream of the investigation
area can provide an understanding of
the overall trend of the stream.
Stream classification systems and chan-
nel evolution models also provide in-
Figure 7.15: Simon's channel evolution stages
related to streambank shape. The cross-
sectional shape of the streambank may be a
good indicator of its evolutionary stage.
Source: Simon 1989. Published by permission of the
American Water Resources Association.
Class I. Premodified Class II. Constructed Class III. Degradation Class Ilia. Degradation
under-
cutting
Class IV. Threshold
Class IVa. Threshold
slab and
rotational
failures
pop-out
failures
vertical
face 70-90°
upper bank
25-50°
previous
profile
degraded
channel
bottom
Class V. Aggradation
vertical
slough line 20-25
fluvial
deposition
Class VI. Restabilization
Class Via. Restabilization
vertical
face
70-90°
£-r substantial
bed-level
recovery
slough line 20
non-dispersive
materials
fluvial
deposition
substantial
bed-level
recovery
moderately
dispersive
materials
fluvial
deposition
Geomorphic Processes
7-37
-------
400.0
100.0
£
o
1
ce
f
-------
usually prevented even by mature
woody vegetation. Conversely, estab-
lishing and managing perennial grasses
and woody vegetation is critical to pro-
tecting streams that are already func-
tioning properly.
Proper Functioning
Condition (PFC)
The Bureau of Land Management (BLM)
has developed guidelines and proce-
dures to rapidly assess whether a stream
riparian area is functioning properly in
terms of its hydrology, landform/soils,
channel characteristics, and vegetation
(Prichard et al. 1993, rev. 1995). This
assessment, commonly called PFC, is
useful as a baseline analysis of stream
condition and physical function, and it
can also be useful in watershed analysis.
It is essential to do a thorough analysis
of the stream corridor and watershed
conditions prior to development of
restoration plans and selection of
restoration approaches to be used.
There are many cases where selection
of the wrong approach has led to
complete failure of stream restoration
efforts and the waste of costs of restora-
tion. In many cases, particularly in
wildland situations, restoration through
natural processes and control of land
uses is the preferred and most cost-ef-
fective method. If hydrologic conditions
are rapidly changing in a drainage, no
restoration might be the wisest course
until equilibrium is restored.
Identifying streams and drainages
where riparian areas along streams are
not in proper functioning condition,
and those at risk of losing function, is
an important first step in restoration
analysis. Physical conditions in riparian
zones are excellent indicators of what is
happening in a stream or the drainage
above.
With the results of PFC analysis, it is
possible to begin to determine stream
corridor and watershed restoration
needs and priorities. PFC results may
also be used to identify where gathering
more detailed information is needed
and where additional data are not
needed.
PFC is a methodology for assessing the
physical functioning of a riparian-
wetland area. It provides information
critical to determining the "health" of a
riparian ecosystem. PFC considers both
abiotic and biotic components as they
relate to the physical functioning of ri-
parian areas, but it does not consider
the biotic component as it relates to
habitat requirements. For habitat analy-
sis, other techniques must be employed.
The PFC procedure is currently a stan-
dard baseline assessment for stream/ri-
parian surveys for the BLM, and PFC is
beginning to be used by the U.S. Forest
Service in the West. This technique is
not a substitute for inventory or moni-
toring protocols designed to yield de-
tailed information on the habitat or
populations of plants or animals depen-
dent on the riparian-stream ecosystem.
PFC is a useful tool for watershed
analysis. Although the assessment is
conducted on a stream reach basis, the
ratings can be aggregated and analyzed
at the watershed scale. PFC, along with
other watershed and habitat condition
information, provides a good picture of
watershed "health" and causal factors
affecting watershed "health." Use of
PFC will help to identify watershed-
scale problems and suggest manage-
ment remedies.
The following are definitions of proper
function as set forth in TR 1737-9:
Proper Functioning Condition
Riparian-wetland areas are function-
ing properly when adequate vegeta-
Geomorphic Processes
7-39
-------
tion, landform, or large woody
debris is present to:
1. Dissipate stream energy associated
with high waterflows, thereby
reducing erosion and improving
water quality.
2. Filter sediment, capture bedload,
and aid floodplain development.
3. Improve floodwater retention and
ground water storage.
4. Develop root masses that stabilize
streambanks against cutting
action.
5. Develop diverse ponding and
channel characteristics to provide
the habitat and the water depth,
duration, and temperature neces-
sary for fish production, waterfowl
breeding, and other uses.
6. Support greater biodiversity.
Functional-at RiskRiparian-wetland
areas that are in functional condi-
tion, but an existing soil, water, or
vegetation attribute makes them sus-
ceptible to degradation.
NonfunctionalRiparian-wetland
areas that clearly are not providing
adequate vegetation, landform, or
large debris to dissipate stream ener-
gy associated with high flow and
thus are not reducing erosion, im-
proving water quality, or performing
other functions as listed above under
the definition of proper function.
The absence of certain physical
attributes, such as absence of a
floodplain where one should be,
is an indicator of nonfunctioning
conditions.
Assessing functionality with the PFC
technique involves procedures for deter-
mining a riparian-wetland area's capa-
bility and potential, and comparing
that potential with current conditions.
Although the PFC procedure defines
streams without floodplains (when a
floodplain would normally be present)
as nonfunctional, many streams that
lose their floodplains through incision
or encroachment still retain ecological
functions. The importance of a flood-
plain needs to be assessed in view of
the site-specific aquatic and riparian
community.
When using the PFC technique, it is
important not to equate "proper func-
tion" with "desired condition." Proper
function is intended to describe the
state in which the stream channel and
associated riparian areas are in a rela-
tively stable and self-sustaining condi-
tion. Properly functioning streams can
be expected to withstand intermediate
flood events (e.g., 25- to 30-year flood
events) without substantial damage to
existing values. However, proper func-
tioning condition will often develop
well before riparian succession provides
shrub habitat for nesting birds. Put an-
other way, proper functioning condition
is a prerequisite to a variety of desired
conditions.
Although based on sound science, the
PFC field technique is not quantitative.
An advantage of this approach is that
it is less time-consuming than other
techniques because measurements are
not required. The procedure is per-
formed by an interdisciplinary team
and involves completing a checklist
evaluating 17 factors dealing with hy-
drology, vegetation, and erosional/
depositional characteristics. Training in
the technique is required, but the tech-
nique is not difficult to learn. With
training, the functional determinations
resulting from surveys are reproducible
to a high degree.
7-40
Chapter 7: Analysis of Corridor Condition
-------
Other advantages of the PFC technique
are that it provides an easy-to-under-
stand "language" for discussing stream
conditions with a variety of agencies
and publics, PFC training is readily
available, and there is growing intera-
gency acceptance of the technique.
Hydraulic Geometry: Streams
in Cross Section
Stream corridor restoration initiatives
frequently involve partial or total recon-
struction of channels that have been se-
verely degraded. Channel
reconstruction design requires criteria
for channel size and alignment. The fol-
lowing material presents an overview of
hydraulic geometry theory and provides
some sample hydraulic geometry rela-
tionships for relating bankfull dimen-
sions to bankfull discharge.
Correlations between certain planform
dimensions (e.g., meander characteris-
tics) of stable alluvial stream channels
to bankfull discharge and channel
width also are discussed.
Hydraulic geometry theory is based on
the concept that a river system tends to
develop in a way that produces an ap-
proximate equilibrium between the
channel and the in-flowing water and
sediment (Leopold and Maddock
1953). The theory typically relates an
independent or driving variable, such as
drainage area or discharge, to depen-
dent variables such as width, depth,
slope, and velocity. Hydraulic geometry
relations are sometimes stratified ac-
cording to bed material size or other
factors. These relationships are empiri-
cally derived, and their development re-
quires a relatively large amount of data.
Figure 7.17 presents hydraulic geome-
try relations based on the mean annual
discharge rather than the bankfull dis-
charge. Similar hydraulic geometry rela-
tionships can be determined for a
watershed of interest by measuring
channel parameters at numerous cross
sections and plotting them against a
discharge. Such plots can be used with
care for planning and preliminary de-
sign. The use of hydraulic geometry re-
lationships alone for final design is not
recommended.
Careful attention to defining stable
channel conditions, channel-forming
discharge, and streambed and bank
characteristics are required in the data
collection effort. The primary role of
discharge in determining channel cross
sections has been clearly demonstrated,
but there is a lack of consensus about
which secondary factors such as sedi-
ment loads, bank materials, and vegeta-
tion are significant, particularly with
respect to width. Hydraulic geometry re-
lationships that do not explicitly con-
sider sediment transport are applicable
mainly to channels with relatively low
bed-material loads (USAGE 1994).
Hydraulic geometry relations can be de-
veloped for a specific river, watershed,
or for streams with similar physio-
graphic characteristics. Data scatter is
expected about the developed curves
even in the same river reach. The more
dissimilar the stream and watershed
characteristics are, the greater the ex-
pected data scatter is. It is important to
recognize that this scatter represents a
valid range of stable channel configura-
tions due to variables such as geology,
vegetation, land use, sediment load and
gradation, and runoff characteristics.
Figures 7.18 and 7.19 show hydraulic
geometry curves developed for the
upper Salmon River watershed in Idaho
(Emmett 1975). The scatter of data for
stable reaches in the watershed indicates
that for a drainage area of 10 square
miles, the bankfull discharge could rea-
sonably range from 100 to 250 cfs and
the bankfull width could reasonably
range from 10 to 35 feet. These relations
Geomorphic Processes
7-41
-------
were developed for a relatively homoge-
neous watershed, yet there is still quite a
bit of natural variation in the data. This
illustrates the importance of viewing
the data used to develop any curve (not
just the curve itself), along with statisti-
cal parameters such as R2 values and
confidence limits. (Refer to a text on
statistics for additional information.)
Given the natural variation related to
stream and watershed characteristics,
Figure 7.17: Channel morphology related to
average annual discharge. Width, depth, and
velocity in relation to mean annual discharge
as discharge increases downstream on 79 rivers
in Wyoming and Montana.
Source: Leopold and Maddock 1953.
500 i
200 -
100 -
the preferred source of data for a hy-
draulic geometry relationship would be
the restoration initiative reach. This
choice may be untenable due to channel
instability. The second preferred choice
is the project watershed, although care
must be taken to ensure that data are
acquired for portions of the watershed
with physiographic conditions similar
to those of the project reach.
Statistically, channel-forming discharge
is a more reliable independent variable
for hydraulic geometry relations than
drainage area. This is because the mag-
nitude of the channel forming discharge
is the driving force that creates the ob-
served channel geometry, and drainage
£ 1.0 -
a
a>
a
18
17
-------
10,000
~ 1000
00
2
HI
Ol
c
ro
CO
100
10
.
08 = 28.3DAO.69
il
uJ
10 100 1000
Drainage Area (DA) (square miles)
10,000
Figure 7.18: Bankfull discharge versus drainage
areaUpper Salmon River area. Curves based
on measured data such as this can be valuable
tools for designing restorations (Emmett T975).
1000i
a»
0)
3 100
ro
t
3
U1
5 10
5
c
IB
to
v.
Road Creek
i i i i i i 11
10 100
Drainage Area (DA) (square miles)
1000
10,000
Figure 7.19: Bankfull surface width versus
drainage areaUpper Salmon River area.
Local variations in bankfull width may be
significant. Road Creek widths are narrower
because of lower precipitation.
Geomorphic Processes
7-43
-------
Hydraulic Geometry and Stability
Assessment
Regime Theory and Hydraulic
Geometry
Regime theory was developed about a century ago by
British engineers working on irrigation canals in what is
now India and Pakistan. Canals that required little main-
tenance were said to be "in regime," meaning that they
conveyed the imposed water and sediment loads in a
state of dynamic equilibrium, with width, depth, and
slope varying about some long-term average. These
engineers developed empirical formulas linking low-
maintenance canal geometry and design discharge by
fitting data from relatively straight canals carrying near-
constant discharges (Blench 1957, 1969; Simons and
Albertson 1963). Since few streams will be restored to
look and act as canals, the regime relationships are not
presented here.
About 50 years later, hydraulic geometry formulas similar
to regime relationships were developed by geomorphol-
ogists studying stable, natural rivers. These rivers, of
course, were not straight and had varying discharges. A
sample of these hydraulic geometry relationship is pre-
sented in the table on the following page. In general,
these formulas take the form:
1 " 50
~ 4 ^ SO
S = k7 Qk* D5;>
where w and D are reach average width and depth in
feet, S is the reach average slope, Dso is the median bed
sediment size in millimeters, and Q is the bankfull dis-
charge in cubic feet per second. These formulas are
most reliable for width, less reliable for depth, and least
reliable for slope.
area is merely a surrogate for discharge.
Typically, channel-forming discharge
correlates best with channel width. Cor-
relations with depth are somewhat less
reliable. Correlations with slope and ve-
locity are the least reliable.
The use of hydraulic geometry relations
to assess the stability of a given channel
reach requires two things. First, the wa-
tershed and stream channel characteris-
tics of the reach in question must be
the same as (or similar to) the data set
used to develop the hydraulic geometry
relations. Second, the reasonable scatter
of the data in the hydraulic geometry
relations must be known. If the data for
a specific reach fall outside the reason-
able scatter of data for stable reaches in
a similar watershed, there is reason to
believe that the reach in question may
be unstable. This is only an indicator,
since variability in other factors (geol-
ogy, land use, vegetation, etc.) may
cause a given reach to plot high or low
on a curve. For instance, in Figure 7.17,
the data points from the Road Creek
subbasin plot well below the line (nar-
rower bankfull surface width) because
the precipitation in this subbasin is
lower. These reaches are not unstable;
they have developed smaller channel
widths in response to lower discharges
(as one would expect).
In summary, the use of hydraulic geom-
etry relations requires that the actual
data be plotted and the statistical coeffi-
cients known. Hydraulic geometry rela-
tions can be used as a preliminary
guide to indicate stability or instability
in stream reaches, but these indications
should be checked using other tech-
niques due to the wide natural variabil-
ity of the data (see Chapter 8 for more
information on assessment of channel
stability).
Regional Curves
Dunne and Leopold (1978) looked at
similar relationships from numerous
watersheds and published regional
curves relating bankfull channel dimen-
7-44
Chapter 7: Analysis of Corridor Condition
-------
sions to drainage area (Figure 7.20).
Using these curves, the width and
depth of the bankfull channel can be
approximated once the drainage area of
a watershed within one of these regions
is known. Obviously, more curves such
as these are needed for regions that ex-
perience different topographic, geo-
logic, and hydrologic regimes; there-
fore, additional regional relationships
should be developed for specific areas
of interest. Several hydraulic geometry
formulas are presented in Table 7.5.
Regional curves should be used only as
indicators to help identify the channel
geometry at a restoration initiative site
500
100
?
01
lu 50
re
3
CT
1/1
ra
s
10
o
-------
Table 7.5: Limits of data sets used to derive regime formulas.
Source: Hey 1988, 1990.
Reference
Lacey1958
Data Source
Indian canals
Median Bed
Material Size
(mm)
0.1 to 0.4
Discharge
(ft3/s)
Cohesive to 100 to
slightly 10,000
cohesive
Sediment
Concentration
(ppm)
<500
Bedforms
Blench 1969
Simons and
Albertson 1963
Nixon 1959
Kellerhals 1967
Bray 1982
Parker 1982
Hey and
Thorne 1986
Indian canals
U.S. and Indian
canals
U.K. rivers
U.S., Canadian, and
Swiss rivers of low
sinuousity, and lab
Sinuous Canadian
rivers
Single channel
Canadian rivers
Meandering U.K.
rivers
0.1 to 0.6
0.318 to
0.465
0.06 to 0.46
Cohesive,
0.029 to 0.36
gravel
7 to 265
1.9 to 145
14to 176
Cohesive 1 to 100,000
Sand 100 to 400
Cohesive 5 to 88,300
Cohesive 137 to 510
700 to
18,050
Noncohesive 1.1 to
70,600
194 to
138,400
Little 353 to
cohesion 211,900
138 to
14,970
<301
<500
< 500
<500
Not measured
Negligible
"Mobile" bed
Qs computed
to range up
to 114
Not
specified
.0001 35 to
.000388
.000059 to
.00034
.000063 to
.000114
.000 17 to
.0131
.00022 to
.015
.0011 to
.021
Ripples to
dunes
Ripples to
dunes
Ripples to
dunes
Plane
Plane
1 Blench (1969) provides adjustment factors for sediment concentrations between 30 and 100 ppm.
because of the large degree of natural
variation in most data sets. Published
hydraulic geometry relationships usu-
ally are based on stable, single-thread
alluvial channels. Channel geometry-
discharge relationships are more com-
plex for multithread channels.
Exponents and coefficients for hydraulic
geometry formulas are usually deter-
mined from data sets for a specific
stream or watershed. The relatively
small range of variation of the expo-
nents k2, k5, and ks is impressive, con-
sidering the wide range of situations
represented. Extremes for the data sets
used to generate the hydraulic geometry
formulas are given in Tables 7.6 and
7.7. Because formula coefficients vary,
applying a given set of hydraulic geom-
etry relationships should be limited to
channels similar to the calibration sites.
This principle severely limits applying
the Lacey, Blench, and Simons and Al-
bertson formulas in channel restoration
work since these curves were developed
using canal data. Additionally, hydraulic
geometry relationships developed for
pristine or largely undeveloped water-
sheds should not be applied to urban
watersheds.
As shown in Table 7.5, hydraulic geom-
etry relationships for gravel-bed rivers
are far more numerous than those for
sand-bed rivers. Gravel-bed relation-
ships have been adjusted for bank soil
characteristics and vegetation, whereas
sand-bed formulas have been modified
to include bank silt-clay content
(Schumm 1977). Parker (1982) argues
in favor of regime-type relationships
based on dimensionless variables. Ac-
cordingly, the original form of the
Parker formula was based on dimen-
sionless variables.
7-46
Chapter 7: Analysis of Corridor Condition
-------
Table 7.6: Coefficients for selected hydraulic geometry formulas.
Author I Year I Data
Nixon
Leopold
etal.
1959 U.K. rivers
Gravel-bed
rivers
1964 Midwestern
U.S.
Ephemeral
streams in
semiarid U.S.
Kellerhals 1967 Field (U.S., Gravel-bed
Canada, and rivers with
Switzerland) paved beds
Schumm
0.5
1.65 0.5
0.5
1.8
Bray
Parker
Hay and
Thorne
1977
1982
1982
and
laboratory
U.S. (Great
Plains) and
Australia
(Riverine
Plains of
New South
Wales)
Canadian
rivers
Single-
channel
Alberta
rivers
and small bed
material
concentration
Sand-bed 37k,
rivers with
properties
shown in
Table 6
Gravel-bed 3.1
rivers
Gravel-bed 6.06
rivers, banks
with little
cohesion
1986 U.K. rivers
1-5% tree/
shrub cover
Greater than
5-50% tree/
shrub cover
0.5
0.545 0.33
0.4
0.3
0.33 0.4
1.258n2b -0.11
-0.49
-0.12^ 0.00062
-0.95
-0.4
0.92a
0.38
0.6k,* 0.29 -0.12a 0.01136k7* -0.32
0.53 -0.07 0.304 0.33 -0.03 0.00033 -0.33
0.444 -0.11 0.161 0.401 -0.0025 0.00127 -0.394
0.59
0.985
Gravel-bed rivers with:
Grassy banks 2.39 0.5
with no trees
or shrubs
0.41
0.37 -0.11
1.84 0.5
1.51 0.5
0.41 0.37 -0.11
-0.09
-0.43 -0.09
Greater than 1.29 0.5
50% shrub
cover or
incised flood
plain
0.41
0.41
0.37 -0.11 0.00296k7** -0.43 -0.09
0.37 -0.11
-0.43 -0.09
material size in Kellerhals' equation is D90
Manning n.
M"0-39, where M is the percent of bank materials finer than 0.074 mm. The discharge used in this equation is mean annual rather than bankfull.
M0'432, where M is the percent of bank materials finer than 0.074 mm. The discharge used in this equation is mean annual rather than bankfull.
M"0-36, where M is the percent of bank materials finer than 0.074 mm. The discharge used in this equation is mean annual rather than bankfull.
D54°'84 Qx°-10, where Qx = bed material transport rate in kg s'1 at water discharge Q, and D54 refers to bed material and is in mm.
Planform and Meander
Geometry: Stream Channel
Patterns
Meander geometry variables are shown
in Figure 7.21. Channel planform
parameters may be measured in the
field or from aerial photographs and
may be compared with published rela-
tionships, such as those identified in
the box. Developing regional relation-
ships or coefficients specific to the site
of interest is, however, preferable to
using published relationships that may
span wide ranges in value. Figure 7.22
shows some planform geometry rela-
tions by Leopold (1994). Meander
geometries that do not fall within the
range of predicted relationships may
indicate stream instability and deserve
attention in restoration design.
Geomorphic Processes
7-47
-------
Table 7.7: Meander geometry equations.
Source: Williams 1986.
(Equation 1 Equation
1 Applicable Range
Number 1
Interrelations between meander features
2
3
1
*
'
8
*
10
o
12
13
Lm=1.25Lb
Lm = 1.63B
Lm = 4.53RC
Lb = 0.8Lm
Lb=1.29B
Lb = 3.77RC
B = 0.61Lm
B = 0.78Lb
B = 2.88RC
RC = 0.22Lm
Rc = 0.26Lb
RC = 0.35B
Relations of channel size to
14 A = 0.0094LJ 53
15
16
"
18
19
20
21
22
23
24
«
A = 0.0149Lb1-53
A = 0.021B1-53
A = 0.117Rc1-53
W = 0.019Lm°-89
W = 0.026Lb°-89
W = 0.031B°-89
W = 0.81R°-89
D = 0.040LrnO-66
D = 0.054Lb°-66
D = 0.0556° 66
D = 0.127Rc°-i>6
1 8.0
-------
Meander Geometry Formulas
Reviews of meander geometry formulas are provided by Nunnally and Shields (1985,
Table 3) and Chitale (1973). Ackers and Charlton (1970) developed a typical formula
that relates meander wavelength and bankfull discharge, Q (cfs), using laboratory data
and checking against field data from a wide range of stream sizes:
L = 38Q0467
There is considerable scatter about this regression line; examination of the plotted data
is recommended. Other formulas, such as this one by Schumm (1977), also incorporate
bed sediment size or the fraction of silt-clay in the channel perimeter:
L= 1890Qm°34/M°74
where d is average discharge (cfs) and M is the percentage of silt-clay in the perimeter
of the channel. These types of relationships are most powerful when developed from
regional data sets with conditions that are typical of the area being restored. Radius of
curvature, r, is generally between 1.5 and 4.5 times the channel width, w, and more
commonly between 2w and 3w, while meander amplitude is 0.5 to 1.5 times the
meander wavelength, L (USACE 1994). Empirical (Apmann 1972, Nanson and Hickin
1983) and analytical (Begin 1981) results indicate that lateral migration rates are
greatest for bends with radii of curvature between 2w and 4w.
Adjustment processes that affect entire
fluvial systems often include channel
incision (lowering of the channel bed
with time), aggradation (raising of the
channel bed with time), planform
geometry changes, channel widening or
narrowing, and changes in the magni-
tude and type of sediment loads. These
processes differ from localized
processes, such as scour and fill, which
can be limited in magnitude and extent.
In contrast, the processes of channel
incision and aggradation can affect long
reaches of a stream or whole stream
systems. Long-term adjustment
processes, such as incision, aggradation,
and channel widening, can exacerbate
local scour problems. Whether
streambed erosion occurs due to local
scour or channel incision, sufficient bed
level lowering can lead to bank instabil-
ity and to changes in channel planform.
It is often difficult to differentiate be-
tween local and systemwide processes
without extending the investigation up-
stream and downstream of the site in
question. This is because channels mi-
grate over time and space and so may
affect previously undisturbed reaches.
For example, erosion at a logjam ini-
tially may be attributed to the deflec-
tion of flows caused by the woody
debris blocking the channel. However,
the appearance of large amounts of
woody debris may indicate upstream
channel degradation related to instabil-
ity of larger scope.
Geomorphic Processes
7-49
-------
1,000,000
100,000
01
01
01
o>
0)
2
10,000
1000
100
10
meanders of rivers and in flumes
meanders of Gulf Stream
meanders on glaciers
I I l
100,000
*:
1 10 100 1000 5 10 100 1000 10,000 100,000
Channel Width (feet) Mean Radius of Curvature (feet)
Figure 7.22: Planform geometry relationships.
Meander geometries that do not plot dose to
the predicted relationship may indicate stream
instability.
Source: Leopold 1994.
Figure 7.23: Bank instability. Determining if
instability is localized or systemwide is impera-
tive to establish a correct path of action.
Determining Stream
Instability: Is It Local or
Systemwide?
Stage of channel evolution is the pri-
mary diagnostic variable for differentiat-
ing between local and systemwide
channel stability problems in a dis-
turbed stream or constructed channel.
During basinwide adjustments, stage of
channel evolution usually varies system-
atically with distance upstream. Down-
stream sites might be characterized by
aggradation and the waning stages of
widening, whereas upstream sites might
be characterized (in progressive up-
stream order) by widening and mild
degradation, then degradation, and if
the investigation is extended far enough
upstream, the stable, predisturbed con-
dition (Figure 7.23). This sequence of
stages can be used to reveal systemwide
instabilities. Stream classification can be
applied in a similar manner to natural
streams. The sequence of stream types
can reveal systemwide instabilities.
Restoration measures often fail, not as
the result of inadequate structural de-
7-50
Chapter 7: Analysis of Corridor Condition
-------
sign, but rather because of the failure of
the designers to incorporate the existing
and future channel morphology into
the design. For this reason, it is impor-
tant for the designer to have some gen-
eral understanding of stream processes
to ensure that the selected restoration
measures will work in harmony with
the existing and future river conditions.
This will allow the designer to assess
whether the conditions at a particular
site are due to local instability processes
or are the result of some systemwide in-
stability that may be affecting the entire
watershed.
Systemwide Instability
The equilibrium of a stream system can
be disrupted by various factors. Once
this occurs, the stream will attempt to
regain equilibrium by making adjust-
ments in the dependent variables. These
adjustments in the context of physical
processes are generally reflected in
aggradation, degradation, or changes in
planform characteristics (meander
wavelength, sinuosity, etc.). Depending
on the magnitude of the change and
the basin characteristics (bed and bank
materials, hydrology, geologic or man-
made controls, sediment sources, etc.),
these adjustments can propagate
throughout the entire watershed and
even into neighboring systems. For this
reason, this type of disruption of the
equilibrium condition is referred to as
system instability. If system instability is
occurring or expected to occur, it is im-
perative that the restoration initiative
address these problems before any bank
stabilization or instream habitat devel-
opment is considered.
Local Instability
Local instability refers to erosion and
deposition processes that are not symp-
tomatic of a disequilibrium condition
in the watershed (i.e., system instabil-
ity). Perhaps the most common form of
local instability is bank erosion along
the concave bank in a meander bend
that is occurring as part of the natural
meander process. Local instability can
also occur in isolated locations as the
result of channel constriction, flow ob-
structions (ice, debris, structures, etc.),
or geotechnical instability. Local insta-
bility problems are amenable to local
bank protection. Local instability can
also exist in channels where severe sys-
tem instability exists. In these situa-
tions, the local instability problems will
probably be accelerated due to the sys-
tem instability, and a more comprehen-
sive treatment plan will be necessary.
Caution must be exercised if only local
treatments on one site are implemen-
ted. If the upstream reach is stable
and the downstream reach is unstable,
a systemwide problem may again be
indicated. The instability may continue
moving upstream unless the root cause
of the instability at the watershed level
is removed or channel stabilization at
and downstream of the site is imple-
mented.
Local channel instabilities often can be
attributed to redirection of flow caused
by debris, structures, or the approach
angle from upstream. During moderate
and high flows, obstructions often re-
sult in vortices and secondary-flow cells
that accelerate impacts on channel
boundaries, causing local bed scour,
erosion of bank toes, and ultimately
bank failures. A general constriction of
the channel cross section from debris
accumulation or a bridge causes a back-
water condition upstream, with acceler-
ation of the flow and scour through the
constriction.
Bed Stability
In unstable channels, the relationship
between bed elevation and time (years)
Geomorphic Processes
7-51
-------
Figure 7.24:
Changes in bed
elevations over
time. Plotting river
bed elevations at
a point along the
river over time can
indicate whether
a major phase of
channel incision is
ongoing or has
passed.
270
265
260
255
South Fork Forked Deer River
river mile = 7.9
_l l_
- 1964 1968 1972 1976 1980 198
S 292
>
« 288
%
1^^^
II 1 1 1 1 1
1958 1962 1986 1970 1974 1978 1982 1986
295
South Fork Obion River
290 L *_ river mile = 5.9
285
280
275
270
1962 1966 1970 1974 1978 1982 1986
Year
can be described by nonlinear func-
tions, where change in response to a
disturbance occurs rapidly at first and
then slows and becomes asymptotic
with time (Figure 7.24). Plotting bed
elevations against time permits evaluat-
ing bed-level adjustment and indicates
whether a major phase of channel inci-
sion has passed or is ongoing. Various
mathematical forms of this function
have been used to characterize bed-level
adjustment at a site and to predict fu-
ture bed elevations. This method also
can provide valuable information on
trends of channel stability at gauged
locations where abundant data from
discharge measurements are available.
Specific Gauge Analysis
Perhaps one of the most useful tools
available to the river engineer or geo-
morphologist for assessing the histori-
cal stability of a river system is the
specific gauge record. A specific gauge
record is a graph of stage for a specific
discharge at a particular stream gauging
location plotted against time (Blench
1969). A channel is considered to be in
equilibrium if the specific gauge record
shows no consistent increasing or de-
creasing trends over time, while an in-
creasing or decreasing trend is
indicative of an aggradational or degra-
dational condition, respectively. An ex-
ample of a specific gauge record is
shown in Figure 7.25.
The first step in a specific gauge analysis
is to establish the stage vs. discharge re-
lationship at the gauge for the period of
record being analyzed. A rating curve is
developed for each year in the period of
record. A regression curve is then fitted
to the data and plotted on the scatter
plot. Once the rating curves have been
developed, the discharges to be used in
the specific gauge record must be se-
lected. This selection depends largely
on the objectives of the study. It is usu-
ally advisable to select discharges that
encompass the entire range of observed
flows. A plot is then developed showing
the stage for the given flow plotted
against time.
Specific gauge records are an excellent
tool for assessing the historical stability
at a specific location. However, specific
gauge records indicate only the condi-
tions in the vicinity of the particular
gauging station and do not necessarily
reflect river response farther upstream
or downstream of the gauge. Therefore,
even though the specific gauge record is
one of the most valuable tools used by
river engineers, it should be coupled
with other assessment techniques to
7-52
Chapter 7: Analysis of Corridor Condition
-------
270 r
265
en 260
o
0)
Ol
ro
255
250
60,000 cfs
40,000 cfs
26,000 cfs
11,000 cfs
6000 cfs
3800 cfs
j_
1930
1940
1950
1960
Year
1970
1980
1990
Figure 7.25: Specific gauge plot for Red River
at Index, Arkansas. Select discharges from the
gauge data that represent the range of flows.
Source: Biedenharn et al. 1997.
assess reach conditions or to make pre-
dictions about the ultimate response on
a river.
Comparative Surveys and Mapping
One of the best methods for directly as-
sessing channel changes is to compare
channel surveys (thalweg and cross
section).
Thalweg surveys are taken along the
channel at the lowest point in the cross
section. Comparison of several thalweg
surveys taken at different points in time
allows the engineer or geomorphologist
to chart the change in the bed elevation
through time (Figure 7.26).
Certain limitations should be consid-
ered when comparing surveys on a
river system. When comparing thalweg
profiles, it is often difficult, especially
on larger streams, to determine any
distinct trends of aggradation or degra-
dation if there are large scour holes,
particularly in bendways. The existence
of very deep local scour holes may
completely obscure temporal variations
in the thalweg. This problem can some-
times be overcome by eliminating the
pool sections and focusing only on the
crossing locations, thereby allowing
aggradational or degradational trends
to be more easily observed.
Although thalweg profiles are a useful
tool, it must be recognized that they re-
flect only the behavior of the channel
bed and do not provide information
about the channel as a whole. For this
reason it is usually advisable to study
changes in the cross-sectional geometry.
Cross-sectional geometry refers to
width, depth, area, wetted perimeter,
hydraulic radius, and channel con-
veyance at a specific cross section.
If channel cross sections are surveyed
at permanent monumented range
locations, the cross-sectional geometry
at different times can be compared
Geomorphic Processes
7-53
-------
340
320
300
S
E 280
260
1977 thalweg
1985 thalweg
county road bridge
j_
260+00 280+00 300+00 320+00
Stationing (100 feet)
340+00
360+00 380+00
Figure 7.26: Comparative thalweg profiles.
Changes in bed elevation over the length of
a stream can indicate areas of transition and
reaches where more information is needed.
Source: Biedenharn et al., USAGE 1997.
directly. The cross section plots for each
range at the various times can be over-
laid and compared. It is seldom the
case, however, that the cross sections are
located in the exact same place year
after year. Because of these problems, it
is often advisable to compare reach-
average values of the cross-sectional
geometry parameters. This requires the
study area to be divided into distinct
reaches based on geomorphic character-
istics. Next, the cross-sectional parame-
ters are calculated at each cross section
and then averaged for the entire reach.
Then the reach-average values can be
compared for each survey. Cross-
sectional variability between bends
(pools) and crossings (riffles) can ob-
scure temporal trends, so it is often
preferable to use only cross sections
from crossing reaches when analyzing
long-term trends of channel change.
Comparison of time-sequential maps
can provide insight into the planform
instability of the channel. Rates and
magnitude of channel migration (bank
caving), locations of natural and man-
made cutoffs, and spatial and temporal
changes in channel width and planform
geometry can be determined from
maps. With these types of data, channel
response to imposed conditions can be
documented and used to substantiate
predictions of future channel response
to a proposed alteration. Planform data
can be obtained from aerial photos,
maps, or field investigations.
Regression Functions for Degradation
Two mathematical functions have been
used to describe bed level adjustments
with time. Both may be used to predict
channel response to a disturbance, sub-
ject to the caution statements below.
The first is a power function (Simon
1989a):
E - a tb
where E = elevation of the channel bed,
in feet; a = coefficient, determined by
7-54
Chapter 7: Analysis of Corridor Condition
-------
regression, representing the premodi-
fied elevation of the channel bed, in
feet; t = time since beginning of adjust-
ment process, in years, where t0 = 1.0
(year prior to onset of the adjustment
process); and b = dimensionless expo-
nent, determined by regression and in-
dicative of the nonlinear rate of channel
bed change (negative for degradation
and positive for aggradation).
The second function is a dimensionless
form of an exponential equation
(Simon 1992):
where
z = the elevation of the channel bed
(at time t)
z =
a =
b-
k =
the elevation of the channel bed
atto
the dimensionless coefficient,
determined by regression and
equal to the dimensionless ele-
vation (z/zj when the equation
becomes asymptotic, a>l =
aggradation, a
-------
obtained using interpolated coefficient
a values and tfl. For channels down-
stream from dams without significant
tributary sediment inputs, the shape of
the a-value curve would be similar but
inverted; maximum amounts of degra-
dation (minimum a values) occur im-
mediately downstream of the dam and
attenuate nonlinearly with distance far-
ther downstream.
Caution: If one of the above mathemati-
cal functions is used to predict future
bed elevations, the assumption is made
that no new disturbances have occurred
to trigger a new phase of channel
change. Downstream channelization,
construction of a reservoir, formation of
a large woody debris jam that blocks
the channel, or even a major flood are
examples of disturbances that can trig-
ger a new period of rapid change.
Figure 7.27:
Coefficient a and b
values for regression
functions for esti-
mating bed level
adjustment versus
longitudinal distance
along stream. Future
bed elevations can
be estimated by
using empirical
equations.
Source: Simon 1989,
1992.
-0.010
Of\f\ T-
.005
-0.000
-0.005
-0.010
-0.015
-0.020
-0.025
-0.030
0 .0
; 'V
\
b-values from equation
F - atb A
U O L ^p
t~
^
fs/
~ 1 1 1 1 1 1
1st adjustment
2nd adjustment
S *
area of maximum
disturbance and
^ mouth of Obion
River forks
i i i
20 30 40 50 60 70 80
Distance Upstream from Mouth (miles)
90
100
1.06
1.04
1.02
jo 1.00
.98
a-values from equation
z/z0 = a + be(-kt)
1st adjustment
2nd adjustment
area of maximum
disturbance and
.96
.94
- 0
A^
-
i i i i i i
^^' mouth of Obion
River forks
i i
i
20 30 40 50 60 70 80
Distance Upstream from Mouth (miles)
90
100
7-56
Chapter 7: Analysis of Corridor Condition
-------
The investigator is cautioned that the
use of regression functions to compute
aggradation and degradation is an em-
pirical approach that might be appro-
priate for providing insight into the
degradational and aggradational
processes during the initial planning
phases of a project. However, this pro-
cedure does not consider the balance
between supply and transport of water
and sediment and, therefore, is not ac-
ceptable for the detailed design of
restoration features.
Sediment Transport Processes
This document does not provide com-
prehensive coverage of sedimentation
processes and analyses critical to stream
restoration. These processes include
erosion, entrainment, transport, deposi-
tion, and compaction. Refer to standard
texts and reference on sediment, includ-
ing Vanoni (1975), Simons and Senturk
(1977), Chang (1988), Richards
(1982), and USAGE (1989a).
Numerical Analyses and Models
to Predict Aggradation and
Degradation
Numerical analyses and models such as
HEC-6 are used to predict aggradation
and degradation (incision) in stream
channels, as discussed in Chapter 8.
Bank Stability
Streambanks can be eroded by moving
water removing soil particles or by col-
lapse. Collapse or mass failure occurs
when the strength of bank materials is
too low to resist gravity forces. Banks
that are collapsing or about to collapse
are referred to as being geotechnically
unstable (Figure 7.28). The physical
properties of bank materials should be
described to aid characterization of po-
tential stability problems and identifica-
tion of dominant mechanisms of bank
instability.
The level of intensity of geotechnical
investigations varies in planning and
design. During planning, enough infor-
mation must be collected to determine
the feasibility of alternatives being con-
sidered. For example, qualitative de-
scriptions of bank stratigraphy
obtained during planning may be all
that is required for identifying domi-
nant modes of failure in a study reach.
Thorne (1992) describes stream recon-
naissance procedures particularly for
recording streambank data.
Qualitative Assessment of Bank
Stability
Natural Streambanks frequently are
composed of distinct layers reflecting
the depositional history of the bank
materials. Each individual sediment
layer can have physical properties quite
different from those of other layers. The
bank profile therefore will respond ac-
cording to the physical properties of
each layer. Since the stability of stream-
Figure 7.28: Bank erosion by undercutting.
Removal of toe slope support leads to instability
requiring geotechnical solutions.
Geomorphic Processes
7-57
-------
banks with respect to failures due to
gravity depends on the geometry of the
bank profile and the physical properties
of the bank materials, dominant failure
mechanisms tend to be closely associ-
ated with characteristic stratigraphy or
succession of layers (Figure 7.29).
A steep bank consisting of uniform lay-
ers of cohesive or cemented soils gener-
ally develops tension cracks at the top
of the bank parallel to the bank align-
ment. Slab failures occur when the
weight of the soil exceeds the strength
of the grain-to-grain contacts within the
soil. As clay content or cementing agent
decreases, the slope of the bank de-
creases; vertical failure planes become
more flat and planar failure surfaces de-
velop. Rotational failures occur when
the bank soils are predominantly cohe-
sive. Block-type failures occur when a
weak soil layer is eroded away and the
layers above the weak layer lose struc-
tural support.
The gravity failure processes described
in Figure 7.29 usually occur after the
banks have been saturated due to pre-
cipitation or high stream stages. The
water adds weight to the soil and re-
duces grain-to-grain contacts and cohe-
sion forces while increasing the pore
pressure. Pore pressure occurs when soil
water in the pore spaces is under pres-
sure from overlying soil and water. Pore
pressure therefore is internal to the soil
mass. When a stream is full, the flowing
Figure 7.29: Relationship of dominant bank
failure mechanisms and associated stratigraph-
ies, (a) Uniform bank undergoing planar type
failure (b) Uniform shallow bank undergoing
rotational type failure (c) Cohesive upper bank,
noncohesive lower bank leads to cantilever
type failure mechanism (d) Complex bank
stratigraphy may lead to piping or sapping
type failures.
Source: Hagerty 1991. \nJournalofHydraulic
Engineering. Vol. 117 Number 8. Reproduced by
permission of ASCE.
A.
steep bank
profile v
planar
failure surface
c.
overhang
generated on
upper bank \
arcuate or
rotational
failure surface
incipient failure plane
m
preferential
retreat of
erodible i
basal layer ~
fine-grained cohesive
upper bank
coarse non-cohesive
lower bank
D.
outflow of
sand and
water
/
fine-grained soil layer
sandy pervious
soil layer
fine-grained
soil layers
1. Seepage Outflow Initiates Soil Loss
outflow
continues
ijiiKjU^i^uji^yjj^jMu
fine-grained soil layer
--° -.4 * ** --- +-f'-~'^-f-
I sandy pervious
~~
soil layer
fine-grained
soil layers
2. Undermined Upper Layer Falls,
Blocks Detached
outflow
continues
~\~ sandy pervious
~~ soil layer
fine-grained
soil layers
3. Failed Blocks Topple or Slide
7-58
Chapter 7: Analysis of Corridor Condition
-------
water provides some support to the
streambanks. When the stream level
drops, the internal pore pressure pushes
out from within and increases the po-
tential for bank failure.
The last situation described in Figure
7.29 involves ground water sapping or
piping. Sapping or piping is the erosion
of soil particles beneath the surface by
flowing ground water. Dirty or sediment-
laden seepage from a streambank indi-
cates ground water sapping or piping is
occurring. Soil layers above the areas of
ground water piping eventually will col-
lapse after enough soil particles have
been removed from the support layer.
Quantitative Assessment of Bank
Stability
When restoration design requires more
quantitative information on soil prop-
erties, additional detailed data need to
be collected (Figure 7.30). Values of co-
hesion, friction angle, and unit weight
of the bank material need to be quanti-
fied. Because of spatial variability, care-
ful sampling and testing programs are
required to minimize the amount of
data required to correctly characterize
the average physical properties of indi-
vidual layers or to determine a bulk av-
erage statistic for an entire bank.
Care must be taken to characterize soil
properties not only at the time of mea-
surement but also for the "worst case"
conditions at which failure is expected
(Thorne et al. 1981). Unit weight, cohe-
sion, and friction angle vary as a func-
tion of moisture content. It usually is
not possible to directly measure bank
materials under worst-case conditions,
due to the hazardous nature of unstable
sites under such conditions. A qualified
geotechnical or soil mechanics engineer
should estimate these operational
strength parameters.
Quantitative analysis of bank instabili-
ties is considered in terms of force and
resistance. The shear strength of the
bank material represents the resistance
of the boundary to erosion by gravity.
Shear strength is composed of cohesive
strength and frictional strength. For the
case of a planar failure of unit length,
the Coulomb equation is applicable
Sr = c + (N - u) tan <|)
where Sr = shear strength, in pounds per
square foot; c = cohesion, in pounds
per square foot; N = normal stress, in
pounds per square foot; u = pore pres-
sure, in pounds per square foot; and (|) =
friction angle, in degrees.Also:
N = W cos 9
where W = weight of the failure block,
in pounds per square foot; and 0 =
angle of the failure plane, in degrees.
bank
Explanation
H = bank height
L = failure plane length
c = cohesion
$ = friction angle
Y = bulk unit weight
W = weight of failure block
soil
' properties
Sr =
N =
e =
bank angle
Wsine (driving force)
cL + Ntan0 (resisting force)
Wcose
(0.51 = 0.50) (failure plane angle)
for the critical case Sa = Sr and:
4c sin I cos0
Hc =
Y(1 -COS [1-0])
Figure 7.30: Forces acting on a channel bank
assuming there is zero pore-water pressure.
Bank stability analyses relate strength of bank
materials to bank height and angles, and to
moisture conditions.
Geomorphic Processes
7-59
-------
The gravitational force acting on the
bank is:
S =Wsin0
a
Factors that decrease the erosional resis-
tance (Sr), such as excess pore pressure
from saturation and the development
of vertical tension cracks, favor bank in-
stabilities. Similarly, increases in bank
height (due to channel incision) and
bank angle (due to undercutting) favor
bank failure by increasing the gravita-
tional force component. In contrast,
vegetated banks generally are drier and
provide improved bank drainage, which
enhances bank stability. Plant roots
provide tensile strength to the soil re-
sulting in reinforced earth that resists
mass failure, at least to the depth of
roots (Yang 1996).
Bank Instability and Channel
Widening
Channel widening is often caused by
increases in bank height beyond the
critical conditions of the bank material.
Simon and Hupp (1992) show that
there is a positive correlation between
the amount of bed level lowering by
degradation and amounts of channel
widening. The adjustment of channel
width by mass-wasting processes repre-
sents an important mechanism of chan-
nel adjustment and energy dissipation in
alluvial streams, occurring at rates cover-
ing several orders of magnitude, up to
hundreds of feet per year (Simon 1994).
Present and future bank stability may be
analyzed using the following procedure:
Measure the current channel geome-
try and shear strength of the channel
banks.
Estimate the future channel geome-
tries and model worst-case pore pres-
sure conditions and average shear
strength characteristics.
For fine-grained soils, cohesion and
friction angle data can be obtained
from standard laboratory testing (triax-
ial shear or unconfined compression
tests) or by in situ testing with a bore-
hole shear test device (Handy and Fox
1967, Luttenegger and Hallberg 1981,
Thorne et al. 1981, Simon and Hupp
1992). For coarse-grained, cohesionless
soils, estimates of friction angles can be
obtained from reference manuals. By
combining these data with estimates of
future bed elevations, relative bank sta-
bility can be assessed using bank stabil-
ity charts.
Bank Stability Charts
To produce bank stability charts such as
the one following, a stability number
(NJ representing a simplification of the
bank (slope) stability equations is used.
The stability number is a function of
the bank-material friction angle (([>) and
the bank angle (i) and is obtained from
a stability chart developed by Chen
(1975) (Figure 7.31) or from Lohnes
and Handy (1968):
Ns = (4 sin i cos ()))/[!- cos (i - ()))]
The critical bank height H, where dri-
ving force S = resisting force Sr for a
given shear strength and bank geometry
is then calculated (Carson and Kirkby
1972):
Hc = N(c/y)
where c =cohesion, in pounds per
square foot, and y = bulk unit weight of
soil in pounds per cubic foot.
Equations are solved for a range of
bank angles using average or ambient
soil moisture conditions to produce the
upper line "Ambient field conditions,
unsaturated." Critical bank height for
worst-case conditions (saturated banks
and rapid decline in river stage) are ob-
tained by solving the equations, assum-
ing that (() and the frictional component
of shear strength goes to 0.0 (Lutton
7-60
Chapter 7: Analysis of Corridor Condition
-------
01
-Q
£
100
80
60
40
20
10
I1
ID
re
2
9
i
0
i i i
75
i 1 i
60
i 1 i
45
i 1 i
30
i 1
15
Figure 7.31: Stability
number (N) as a
function of bank
angle (i) for a failure
surface passing
through the bank
toe. Critical bank
height for worst-case
condition can be
computed.
Source: Chen 1975.
Slope Angle I (degrees)
1974) and by using a saturated bulk-
unit weight. These results are repre-
sented by the lower line, "saturated
conditions."
The frequency of bank failure for the
three stability classes (unstable, at-risk,
and stable) is subjective and is based
primarily on empirical field data (Fig-
ure 7.32). An unstable channel bank
can be expected to fail at least annually
and possibly after each major storm-
flow in which the channel banks are
saturated, assuming that there is at least
one major stoonflow in a given year.
At-risk conditions translate to a bank
failure every 2 to 5 years, again assum-
ing that there is a major flow event to
saturate the banks and to erode toe ma-
terial. Stable banks by definition do not
fail by mass wasting processes. How-
ever, channel banks on the outside of
meander bends may experience erosion
of the bank toe, leading to oversteepen-
ing of the bank profile and eventually
to bank caving episodes.
Generalizations about critical bank
heights (HJ and angles can be made
Geomorphic Processes
with knowledge of the variability in co-
hesive strengths. Five categories of
mean cohesive strength of channel
banks are identified in Figure 7.33.
Critical bank heights above the mean
low-water level and saturated condi-
tions were used to construct the figure
because bank failures typically occur
during or after the recession of peak
flows. The result is a nomograph giving
critical bank heights for a range of bank
angles and cohesive strengths that can
be used to estimate stable bank config-
urations for worst-case conditions, such
as saturation during rapid decline in
river stage. For example, a saturated
bank at an angle of 55 degrees and a
&
U
40
30
r 20
unstable
^v
at risk
ambient field
conditions,
unsaturated
c
TO
CD
u
V-»
10
8
7
b
1
1
stable
"
w
N^ saturated
conditions
i i i
90 80 70 60 50
Bank Angle (degrees)
40
Figure 7.32:
Example of a bank
stability chart for
estimating critical
bank height (H).
Existing bank
stability can be
assessed, as well
as potential stable
design heights
and slopes.
7-61
-------
100
j? 10
: c = cohesion, in pounds per square
inch
(D
DQ
u
100 90 80 70 60 50 40 30
Bank Angle (degrees)
Figure 7.33: Critical bank-slope configurations
for various ranges of cohesive strengths under
saturated conditions. Specific data on the
cohesive strength of bank materials can be
collected to determine stable configurations.
cohesive strength of 1.75 pounds per
square inch would be unstable when
bank heights exceed about 10 feet.
Predictions of Bank Stability and
Channel Width
Bank stability charts can be used to
determine the following:
The timing of the initiation of gener-
al bank instabilities (in the case of
degradation and increasing bank
heights).
original floodplain surface
.,uU4bUJh
E
3
M
ro
Q
-O
OJ
5
10
15
20
25
m
" 30
I 35
5
v 40
future
channel
widening by
mass-wasting
process
I
projection
of slough-line angle
I
channel centerline
I i I
100 80 60 40 20 0
Distance from Centerline of Channel (feet)
Figure 7.34: Method to estimate future channel widening
(10-20 years) for one side of the channel. The ultimate bank
width can be predicted so that the future stream morphology
can be visualized.
m The timing of renewed bank stability
(in the case of aggradation and
decreasing bank heights).
The bank height and angle needed
for a stable bank configuration under
a range of moisture conditions.
Estimates of future channel widening
also can be made using measured
channel-width data over a period of
years and then fitting a nonlinear func-
tion to the data (Figure 7.34). Williams
and Wolman (1984) used a dimension-
less hyperbolic function of the follow-
ing form to estimate channel widening
downstream from dams:
where:
W. = initial channel width, in feet
Wt = channel width at t years after
Wj, in feet
t = time, in years
}i = intercept
j2 = slope of the fitted straight line on a
plot of W./ Wt versus 1/t
Wilson and Turnipseed (1994) used a
power function to describe widening
after channelization and to estimate fu-
ture channel widening in the loess area
of northern Mississippi:
W = x t"
where:
W = channel width, in feet
x = coefficient, determined by regres-
sion, indicative of the initial channel
width
t = time, in years
d = coefficient, determined by regres-
sion, indicative of the rate of channel
widening.
7-62
Chapter 7: Analysis of Corridor Condition
-------
7.C Chemical Characteristics
Assessing water chemistry in a stream
restoration initiative can be one of the
ways to determine if the restoration was
successful. A fundamental understand-
ing of the chemistry of a given system is
critical for developing appropriate data
collection and analysis methods. Al-
though data collection and analysis are
interdependent, each has individual
components. It is also critical to have a
basic understanding of the hydrologic
and water quality processes of interest
before data collection and analysis
begin. Averett and Schroder (1993) dis-
cuss some fundamental concepts used
when determining a data collection and
analysis program.
Data Collection
Constituent Selection
Hundreds of chemical compounds can
be used to describe water quality. It is
typically too expensive and too time-
consuming to analyze every possible
chemical of interest in a given system.
In addition to selecting a particular
constituent to sample, the analytical
techniques used to determine the con-
stituent also must be considered. An-
other consideration is the chemistry of
the constituent; for example, whether
the chemical is typically in the dis-
solved state or sorbed onto sediment
makes a profound difference in the
methods used for sampling and analy-
sis, as well as the associated costs.
Often it is effective to use parameters
that integrate or serve as indicators for a
number of other variables. For instance,
dissolved oxygen and temperature mea-
surements integrate the net impact of
many physical and chemical processes
on a stream system, while soluble reac-
tive phosphorus concentration is often
taken as a readily available indicator of
the potential for growth of attached
algae. Averett and Schroder (1993)
discuss additional factors involved in
selecting constituents to sample.
Sampling Frequency
The needed frequency of sampling de-
pends on both the constituent of inter-
est and management objectives. For
instance, a management goal of reduc-
ing average instream nutrient concentra-
tions may require monitoring at regular
intervals, whereas a goal of maintaining
adequate dissolved oxygen (DO) during
summer low flow and high temperature
periods may require only targeted mon-
itoring during critical conditions. In
general, water quality constituents that
are highly variable in space or time re-
quire more frequent monitoring to be
adequately characterized.
In many cases, the concentration of a
constituent depends on the flow condi-
tion. For example, concentrations of a
hydrophobic pesticide, which sorbs
strongly to paniculate matter, are likely
to be highest during scouring flows or
erosion washoff events, whereas con-
centrations of a dissolved chemical that
is loaded to the stream at relatively
steady rates will exhibit highest concen-
trations in extremely low flows.
In fact, field sampling and water quality
analyses are time-consuming and ex-
pensive, and schedule and budget con-
straints often determine the frequency
of data collection. Such constraints
make it even more important to design
data collection efforts that maximize
the value of the information obtained.
Statistical tools often are used to help
determine the sampling frequency. Sta-
tistical techniques, such as simple ran-
Chemical Characteristics
7-63
-------
dom sampling, stratified random sam-
pling, two-stage sampling, and system-
atic sampling, are described in Gilbert
(1987) and Averett and Schroder
(1993). Sanders et al. (1983) also de-
scribe methods of determining sam-
pling frequency.
Sire Selection
The selection of sampling sites is the
third critical part of a sampling design.
Most samples represent a point in space
and provide direct information only on
what is happening at that point. A key
objective of site selection is to choose a
site that gives information that is repre-
sentative of conditions throughout a
particular reach of stream. Because most
hydrologic systems are very complex, it
is essential to have a fundamental un-
derstanding of the area of interest to
make this determination.
External inputs, such as tributaries or ir-
rigation return flow, as well as output,
such as ground water recharge, can dras-
tically change the water quality along
the length of a stream. It is because of
these processes that the hydrologic sys-
tem must be understood to interpret
the data from a particular site. For ex-
ample, downstream from a significant
lateral source of a load, the dissolved
constituent(s) might be distributed uni-
formly in the stream channel. Partial -
late matter, however, typically is
stratified. Therefore, the distribution of
a constituent sorbed onto paniculate
matter is not evenly distributed. Averett
and Schroder (1993) discuss different
approaches to selecting sites to sample
both surface water and ground water.
Sanders et al. (1983) and Stednick
(1991) also discuss site selection.
Finally, practical considerations are an
important part of sample collection.
Sites first must be accessible, preferably
under a full range of potential flow and
weather conditions. For this reason,
sampling is often conducted at bridge
crossings, taking into consideration the
degree to which artificial channels at
bridge crossings may influence sample
results. Finally, where constituent loads
and concentrations are of interest, it is
important to align water quality sample
sites with locations at which flow can
be accurately gauged.
Sampling Techniques
This section provides a brief overview of
water quality sampling and data collec-
tion techniques for stream restoration
efforts. Many important issues can be
treated only cursorily within the context
of this document, but a number of ref-
erences are available to provide the
reader with more detailed guidance.
Key documents describing methods of
water sample collection for chemical
analysis are the U.S. Geological Survey
(USGS) protocol for collecting and pro-
cessing surface water samples for deter-
mining inorganic constituents in
filtered water (Horwitz et al. 1994), the
field guide for collecting and processing
stream water samples for the National
Water Quality Assessment program
(Shelton 1994), and the field guide for
collecting and processing samples of
streambed sediment for analyzing trace
elements and organic contaminants for
the National Water Quality Assessment
program (Shelton and Capel 1994). A
standard reference document describing
methods of sediment collection is the
USGS Techniques for Water-Resource In-
vestigations, Field Methods for Measure-
ment of Fluvial Sediment (Guy and
Norman 1982). The USGS is preparing
a national field manual that describes
techniques for collecting and processing
water quality samples (Franceska Wilde,
personal communication, 1997).
7-64
Chapter 7: Analysis of Corridor Condition
-------
Sampling Protocols for
Water and Sediment
Stream restoration monitoring may in-
volve sampling both water and sedi-
ment quality. These samples may be
collected by hand (manual samples), by
using an automated sampler (automatic
samples), as individual point-in-time
samples (grab or discrete samples), or
combined with other samples (compos-
ite samples). Samples collected and
mixed in relation to the measured vol-
ume within or flow through a system
are commonly termed volume- or flow-
weighted composite samples, whereas
equal-volume samples collected at regu-
lar vertical intervals through a portion
or all of the water column may be
mixed to provide a water column com-
posite sample.
Manual Sampling and Grab Sampling
Samples collected by hand using vari-
ous types of containers or devices to
collect water or sediment from a receiv-
ing water or discharge often are termed
grab samples. These samples can re-
quire little equipment and allow record-
ing miscellaneous additional field
observations during each sampling visit.
Manual sampling has several advan-
tages. These approaches are generally
uncomplicated and often inexpensive
(particularly when labor is already
available). Manual sampling is required
for sampling some pollutants. For ex-
ample, according to Standard Methods
(APHA 1995), oil and grease, volatile
compounds, and bacteria must be ana-
lyzed from samples collected using
manual methods. (Oil, grease, and bac-
teria can adhere to hoses and jars used
in automated sampling equipment,
causing inaccurate results; volatile com-
pounds can vaporize during automated
sampling procedures or can be lost
from poorly sealed sample containers;
and bacteria populations can grow and
community compositions change dur-
ing sample storage.)
Disadvantages of grab sampling include
the potential for personnel to be avail-
able around the clock to sample during
storms and the potential for personnel
to be exposed to hazardous conditions
during sampling. Long-term sampling
programs involving many sampling lo-
cations can be expensive in terms of
labor costs.
Grab sampling is often used to collect
discrete samples that are not combined
with other samples. Grab samples can
also be used to collect volume- or flow-
weighted composite samples, where
several discrete samples are combined
by proportion to measured volume or
flow rates; however, this type of sam-
pling is often more easily accomplished
using automated samplers and flow me-
ters. Several examples of manual meth-
ods for flow weighting are presented in
USEPA (1992a). Grab sampling also
may be used to composite vertical water
column or aerial composite samples of
water or sediment from various kinds of
water bodies.
Automatic Sampling
Automated samplers have been im-
proved greatly in the last 10 years and
now have features that are useful for
many sampling purposes. Generally,
such sampling devices require larger
initial capital investments or the pay-
ment of rental fees, but they can reduce
overall labor costs (especially for long-
running sampling programs) and in-
crease the reliability of flow-weighted
compositing.
Some automatic samplers include an
upper part consisting of a microproces-
sor-based controller, a pump assembly,
and a filling mechanism, and a lower
part containing a set of glass or plastic
sample containers and a well that can
be filled with ice to cool the collected
Chemical Characteristics
7-65
-------
samples. More expensive automatic
samplers can include refrigeration
equipment in place of the ice well; such
devices, however, require a 120-volt
power supply instead of a battery. Also,
many automatic samplers can accept
input signals from a flowmeter to acti-
vate the sampler and to initiate a flow-
weighting compositing program. Some
samplers can accept input from a rain
gauge to activate a sampling program.
Most automatic samplers allow collect-
ing multiple discrete samples or single
or multiple composited samples. Also,
samples can be split between sample
bottles or can be composited into a sin-
gle bottle. Samples can be collected on
a predetermined time basis or in pro-
portion to flow measurement signals
sent to the sampler.
In spite of the obvious advantages of
automated samplers, they have some
disadvantages and limitations. Some
pollutants cannot be sampled by auto-
mated equipment unless only qualita-
tive results are desired. Although the
cleaning sequence provided by most
such samplers provide reasonably sepa-
rate samples, there is some cross-conta-
mination of the samples since water
droplets usually remain in the tubing.
Debris in the sampled receiving water
can block the sampling line and pre-
vent sample collection. If the sampling
line is located in the vicinity of a
flowmeter, debris caught on the sam-
pling line can also lead to erroneous
flow measurements.
While automatic samplers can reduce
manpower needs during storm and
runoff events, these devices must be
checked for accuracy during these
events and must be regularly tested and
serviced. If no field checks are made
during a storm event, data for the entire
event may be lost. Thus, automatic sam-
plers do not eliminate the need for field
personnel, but they can reduce these
needs and can produce flow-weighted
composite samples that might be te-
dious or impossible using manual
methods.
Discrete versus Composite Sampling
Flow rates, physical conditions, and
chemical constituents in surface waters
often vary continuously and simultane-
ously. This presents a difficulty when
determining water volumes, pollutant
concentrations, and masses of pollu-
tants or their loads in the waste dis-
charge flows and in receiving waters.
Using automatic or continuously
recording flowmeters allows obtaining
reasonable and continuous flow rate
measurements for these waters. Pollu-
tant loads can then be computed by
multiplying these flow volumes over the
period of concern by the average pollu-
tant concentration determined from the
discrete or flow-composited samples.
When manual (instantaneous) flow
measurements are used, actual volume
flows over time can be estimated only
for loading calculations, adding addi-
tional uncertainty to loading estimates.
Analyzing constituents of concern in a
single grab sample collection provides
the minimum information at the mini-
mum cost. Such an approach, however,
could be appropriate where conditions
are relatively stable; for example, during
periods without rainfall or other poten-
tial causes of significant runoff and
when the stream is well-mixed. Most
often, the usual method is to collect a
random or regular series of grab sam-
ples at predefined intervals during
storm or runoff events.
When samples are collected often
enough, such that concentration
changes between samples are mini-
mized, a clear pattern or time series for
the pollutant's concentration dynamics
can be obtained. When sampling inter-
7-66
Chapter 7: Analysis of Corridor Condition
-------
vals are spaced too far apart in relation
to changes in the pollutant concentra-
tion, less clear understanding of these
relationships is obtained. Mixing sam-
ples from adjacent sampling events or
regions (compositing) requires fewer
samples to be analyzed; for some as-
sessments, this is a reasonable ap-
proach. Sample compositing provides a
savings, especially related to costs for
water quality analyses, but it also results
in loss of information. For example, in-
formation on maximum and minimum
concentrations during a runoff event is
usually lost. But compositing many
samples collected through multiple pe-
riods during the events can help ensure
that the samples analyzed do not in-
clude only extreme conditions that are
not entirely representative of the event.
Even though analytical results from
composited samples rarely equal aver-
age conditions for the event, they can
still be used, when a sufficient distribu-
tion of samples is included, to provide
reasonably representative conditions for
computing loading estimates. In some
analyses, however, considerable errors
can be made when using analytical re-
sults from composited samples in com-
pleting loading analyses. For example,
when maximum pollutant concentra-
tions accompany the maximum flow
rates, yet concentrations in high and
low flows are treated equally, true load-
ings can be underestimated.
Consequently, when relationships be-
tween flow and pollutant concentra-
tions are unknown, it is often
preferable initially to include in the
monitoring plan at least three discrete
or multiple composite sample collec-
tions: during the initial period of in-
creasing flow, during the period of the
peak or plateau flow, and during the pe-
riod of declining flow.
The most useful method for sample
compositing is to combine samples in
relation to the flow volume occurring
during study period intervals. There are
two variations for accomplishing flow-
weighted compositing:
1. Collect samples at equal time inter-
vals at a volume proportional to the
flow rate (e.g., collect 100 mL of sam-
ple for every 100 gallons of flow that
passed during a 10-minute interval)
or
2. Collect equal-volume samples at
varying times proportional to the
flow (e.g., collect a 100-mL sample
for each 100 gallons of flow, irrespec-
tive of time).
The second method is preferable for es-
timating load accompanying wet
weather flows, since it results in sam-
ples being collected most often when
the flow rate is highest.
Another compositing method is time-
composited sampling, where equal
sample volumes are collected at equally
spaced time intervals (e.g., collect 100
mL of sample every 10 minutes during
the monitored event). This approach
provides information on the average
conditions at the sampling point during
the sampling period. It should be used,
for example, to determine the average
toxic concentrations to which resident
aquatic biota are exposed during the
monitored event.
Field Analyses of Water Quality
Samples
Concentrations of various water quality
parameters may be monitored both in
the field and in samples submitted to a
laboratory (Figure 7.35). Some parame-
ters, such as water temperature, must be
obtained in the field. Parameters such
as concentrations of specific synthetic
organic chemicals require laboratory
analysis. Other parameters, such as nu-
Chemical Characteristics
7-67
-------
Figure 7.35: Field sampling. Sampling can also
be automated.
trient concentrations, can be measured
by both field and laboratory analytical
methods. For chemical constituents,
field measurements generally should be
considered as qualitative screening val-
ues since rigorous quality control is not
possible. In addition, samples collected
for compliance with Clean Water Act re-
quirements must be analyzed by a labo-
ratory certified by the appropriate
authority, either the state or the USEPA.
The laboratories must use analytic tech-
niques listed in the Code of Federal Regu-
lations (CFR), Title 40, Part 136,
"Guidelines Establishing Test Proce-
dures for Analysis of Pollutants Under
the Clean Water Act."
The balance of this subsection notes
special considerations regarding those
parameters typically sampled and ana-
lyzed in the field, including pH, tem-
perature, and dissolved oxygen (DO).
PH
Levels of pH can change rapidly in sam-
ples after collection. Consequently, pH
often is measured in the field using a
hand-held pH electrode and meter.
Electrodes are easily damaged and con-
taminated and must be calibrated with
a standard solution before each use.
During calibrations and when site mea-
surements are conducted, field instru-
ments should be at thermal equilibrium
with the solutions being measured.
Temperature
Because water temperature changes
rapidly after collection, it must be mea-
sured either in the field (using in situ
probes) or immediately after collecting
a grab sample. EPA Method 170.1 de-
scribes procedures for thermometric de-
termination of water temperature.
Smaller streams often experience wide
diurnal variations in temperature, as
well as pH and DO. Many streams also
experience vertical and longitudinal
variability in temperature from shading
and flow velocity. Because of the effect
of temperature on other water quality
factors, such as dissolved oxygen con-
centration, temperatures always should
be recorded when other field measure-
ments are made.
Dissolved Oxygen
When multiple DO readings are re-
quired, a DO electrode and meter (EPA
method 360.1) are typically used. To
obtain accurate measurements, the Win-
kler titration method should be used to
calibrate the meter before and after each
day's use. Often it is valuable to recheck
the calibration during days of intensive
use, particularly when the measure-
ments are of critical importance.
Oxygen electrodes are fragile and sub-
ject to contamination, and they need
7-68
Chapter 7: Analysis of Corridor Condition
-------
frequent maintenance. Membranes cov-
ering these probes must be replaced
when bubbles form under the mem-
brane, and the electrode should be kept
full of fresh electrolyte solution. If the
meter has temperature and salinity
compensation controls, they should be
used carefully, according to the manu-
facturer's instructions.
Water Quality Sample
Preparation and Handling for
Laboratory Analysis
Sample collection, preparation, preser-
vation, and storage guidelines are de-
signed to minimize altering sample
constituents. Containers must be made
of materials that will not interact with
pollutants in the sample, and they
should be cleaned in such a way that
neither the container nor the cleaning
agents interfere with sample analysis.
Sometimes, sample constituents must
be preserved before they degrade or
transform prior to analysis. Also, speci-
fied holding times for the sample must
not be exceeded. Standard procedures
for collecting, preserving, and storing
samples are presented in APHA (1995)
and at 40 CFR Part 136. Useful material
also is contained in the USEPA NPDES
Storm Water Sampling Guidance Docu-
ment (1992a).
Most commercial laboratories provide
properly cleaned sampling containers
with appropriate preservatives. The lab-
oratories also usually indicate the maxi-
mum allowed holding periods for each
analysis. Acceptable procedures for
cleaning sample bottles, preserving
their contents, and analyzing for appro-
priate chemicals are detailed in various
methods manuals, including APHA
(1995) and USEPA (1979a). Water sam-
plers, sampling hoses, and sample stor-
age bottles always should be made of
materials compatible with the goals of
the study. For example, when heavy
metals are the concern, bottles should
not have metal components that can
contaminate the collected water sam-
ples. Similarly, when organic contami-
nants are the concern, bottles and caps
should be made of materials not likely
to leach into the sample.
Sample Preservation, Handling,
and Storage
Sample preservation techniques and
maximum holding times are presented
in APHA (1995) and 40 CFR Part 136.
Cooling samples to a temperature of
4 degrees Celsius (°C) is required for
most water quality variables. To accom-
plish this, samples are usually placed in
a cooler containing ice or an ice substi-
tute. Many automated samplers have a
well next to the sample bottles to hold
either ice or ice substitutes. Some more
expensive automated samplers have re-
frigeration equipment requiring a
source of electricity. Other preservation
techniques include pH adjustment and
chemical fixation. When needed, pH
adjustments are usually made using
strong acids and bases, and extreme
care should be exercised when handing
these substances.
Bacterial analysis may be warranted,
particularly where there are concerns re-
garding inputs of sewage and other
wastes or fecal contamination. Bacterial
samples have a short holding time and
are not collected by automated sampler.
Similarly, volatile compounds must be
collected by grab sample, since they are
lost through volatilization in automatic
sampling equipment.
Sample Labeling
Samples should be labeled with water-
proof labels. Enough information
should be recorded to ensure that each
sample label is unique. The information
recorded on sample container labels
also should be recorded in a sampling
notebook kept by field personnel. The
Chemical Characteristics
7-69
-------
label typically includes the following
information:
Name of project.
Location of monitoring.
Specific sample location.
Date and time of sample collection.
Name or initials of sampler.
Analysis to be performed.
Sample ID number.
Preservative used.
Type of sample (grab, composite).
Sample Packaging and Shipping
It is sometimes necessary to ship sam-
ples to the laboratory. Holding times
should be checked before shipment to
ensure that they will not be exceeded.
Although wastewater samples are not
usually considered hazardous, some
samples, such as those with extreme
pH, require special procedures. If the
sample is shipped through a common
carrier or the U.S. Postal Service, it must
comply with Department of Transporta-
tion Hazardous Material Regulations
(49 CFR Parts 171-177). Air shipment
of samples defined as hazardous may
be covered by the requirements of the
International Air Transport Association.
Samples should be sealed in leakproof
bags and padded against breakage.
Many samples must be packed with an
ice substitute to maintain a temperature
of 4 degrees C during shipment. Plastic
or metal recreational coolers make ideal
shipping containers because they pro-
tect and insulate the samples. Accompa-
nying paperwork, such as the
chain-of-custody documentation,
should be sealed in a waterproof bag in
the shipping container.
Chain of Custody
Chain-of-custody forms document each
change in possession of a sample, start-
ing at its collection and ending when it
is analyzed. At each transfer of posses-
sion, both the relinquisher and the re-
ceiver of the samples are required to
sign and date the form. The form and
the procedure document possession of
the samples and help prevent tamper-
ing. The container holding samples also
can be sealed with a signed tape or seal
to help ensure that samples are not
compromised.
Copies of the chain-of-custody form
should be retained by the sampler and
by the laboratory. Contract laboratories
often supply chain-of-custody forms
with sample containers. The form is
also useful for documenting which
analyses will be performed on the sam-
ples. These forms typically contain the
following information:
Name of project and sampling loca-
tions.
Date and time that each sample is
collected.
Names of sampling personnel.
Sample identification names and
numbers.
Types of sample containers.
Analyses performed on each sample.
Additional comments on each
sample.
Names of all those transporting the
samples.
Collecting and Handling
Sediment Quality Samples
Sediments are sinks for a wide variety
of materials. Nonpoint source dis-
charges typically include large quanti-
ties of suspended material that settle
out in sections of receiving waters hav-
ing low water velocities. Nutrients,
metals, and organic compounds can
bind to suspended solids and settle to
the bottom of a water body when flow
7-70
Chapter 7: Analysis of Corridor Condition
-------
velocity is insufficient to keep them in
suspension. Contaminants bound to
sediments may remain separated from
the water column, or they may be resus-
pended in the water column.
Flood scouring, bioturbation (mixing
by biological organisms), desorption,
and biological uptake all promote the
release of adsorbed pollutants. Organ-
isms that live and feed in sediment are
especially vulnerable to contaminants
in sediments. Having entered the food
chain, contaminants can pass to feeders
at higher food (trophic) levels and can
accumulate or concentrate in these or-
ganisms. Humans can ingest these con-
taminants by eating fish.
Sediment deposition also can physically
alter benthic (bottom) habitats and af-
fect habitat and reproductive potentials
for many fish and invertebrates. Sedi-
ment sampling should allow all these
impact potentials to be assessed.
Collection Techniques
Sediment samples are collected using
hand- or winch-operated dredges. Al-
though a wide variety of dredges are
available, most operate in the following
similar fashion:
1. The device is lowered or pushed
through the water column by hand
or winch.
2. The device is released to allow clo-
sure, either by the attached line or by
a weighted messenger that is
dropped down the line.
3. The scoops or jaws of the device
close either by weight or spring
action.
4. The device is retrieved to the surface.
Ideally, the device disturbs the bottom
as little as possible and closes fully so
that fine particles are not lost. Com-
mon benthic sampling devices include
the Ponar, Eckman, Peterson, Orange-
peel, and Van Veen dredges. When in-
formation is needed about how chemi-
cal depositions and accumulations have
varied through time, sediment cores can
be collected with a core sampling de-
vice. Very low density or very coarse
sediments can be sampled by freeze
coring. A thorough description of sedi-
ment samplers is included in Klemm et
al. (1990).
Sediment sampling techniques are use-
ful for two types of investigations re-
lated to stream assessments:
(1) chemical analysis of sediments and
(2) investigation of benthic macroinver-
tebrate communities. In either type of
investigation, sediments from reference
stations should be sampled so that they
can be compared with sediments in the
affected receiving waters. Sediments
used for chemical analyses should be
removed from the dredge or core sam-
ples by scraping back the surface layers
of the collected sediment and extracting
sediments from the central mass of the
collected sample. This helps to avoid
possible contamination of the sample
by the sample device. Sediment samples
for toxicological and chemical examina-
tion should be collected following
method E 1391 detailed in ASTM
(1991). Sediments for benthic popula-
tion analyses may be returned in total
for cleaning and analysis or may receive
a preliminary cleaning in the field using
a No. 30 sieve.
Sediment Analyses
There are a variety of sediment analysis
techniques, each designed with inherent
assumptions about the behavior of sed-
iments and sediment-bound contami-
nants. An overview of developing
techniques is presented in Adams et al.
(1992). EPA has evaluated 11 of the
methods available for assessing sedi-
ment quality (USEPA 1989b). Some of
the techniques may help to demonstrate
Chemical Characteristics
7-71
-------
attainment of narrative requirements of
some water quality standards. Two of
these common analyses are introduced
briefly in the following paragraphs.
Bulk sediment analyses analyze the
total concentration of contaminants
that are either bound to sediments or
present in pore water. Results are re-
ported in milligrams or micrograms per
kilogram of sediment material. This
type of testing often serves as a screen-
ing analysis to classify dredged material.
Results of bulk testing tend to overesti-
mate the mass of contaminants that
will be available for release or for bio-
logical uptake because a portion of the
contaminants are not biologically avail-
able or likely to dissolve.
Elutriate testing estimates the amount of
contaminants likely to be released from
sediments when mixed with water. In
an elutriate test, sediment is mixed with
water and then agitated. The standard
elutriate test for dredge material mixes
four parts water from the receiving
water body with one part sediment
(USEPA 1990). After vigorous mixing,
the sample is allowed to settle before
the supernatant is filtered and analyzed
for contaminants. This test was de-
signed to estimate the amount of mate-
rial likely to enter the dissolved phase
during dredging; however, it is also use-
ful as a screening test for determining
whether further testing should be per-
formed and as a tool for comparing
sediments upstream and downstream of
potential pollutant sources.
Data Management
All monitoring data should be orga-
nized and stored in a readily accessible
form. The potentially voluminous and
diverse nature of the data, and the vari-
ety of individuals who can be involved
in collecting, recording, and entering
data, can easily lead to the loss of data
or the recording of erroneous data. Lost
or erroneous data can severely damage
the quality of monitoring programs. A
sound and efficient data management
program for a monitoring program
should focus on preventing such prob-
lems. This requires that data be man-
aged directly and separately from the
activities that use them.
Data management systems include tech-
nical and managerial components. The
technical components involve selecting
appropriate computer equipment and
software and designing the database, in-
cluding data definition, data standard-
ization, and a data dictionary. The
managerial components include data
entry, data validation and verification,
data access, and methods for users to
access the data.
To ensure the integrity of the database,
it is imperative that data quality be con-
trolled from the point of collection to
the time the information is entered into
the database. Field and laboratory per-
sonnel must carefully enter data into
proper spaces on data sheets and avoid
transposing numbers. To avoid tran-
scription errors, entries into a database
should be made from original data
sheets or photocopies. As a preliminary
screen for data quality, the database de-
sign should include automatic parame-
ter range checking. Values outside the
defined ranges should be flagged by the
program and immediately corrected or
included in a follow-up review of the
entered data. For some parameters, it
might be appropriate to include auto-
matic checks to disallow duplicate val-
ues. Preliminary database files should
be printed and verified against the orig-
inal data to identify errors.
Additional data validation can include
expert review of the verified data to
identify possible suspicious values.
Sometimes, consultation with the indi-
7-72
Chapter 7: Analysis of Corridor Condition
-------
viduals responsible for collecting or en-
tering original data is required to resolve
problems. After all data are verified and
validated, they can be merged into the
monitoring program's master database.
To prevent loss of data from computer
failure, at least one set of duplicate
(backup) database files should be
maintained at a location other than
where the master database is kept.
Quality Assurance and Quality
Control (QAIQC)
Quality assurance (QA) is the manage-
ment process to ensure the quality of
data. In the case of monitoring projects,
it is managing environmental data col-
lection to ensure the collection of high-
quality data. QA focuses on systems,
policies, procedures, program structures,
and delegation of responsibility that
will result in high-quality data. Quality
control (QC) is a group of specific pro-
cedures designed to meet defined data
quality objectives. For example, equip-
ment calibration and split samples are
QC procedures. QA/QC procedures are
essential to ensure that data collected in
environmental monitoring programs are
useful and reliable.
The following are specific QA plans re-
quired of environmental monitoring
projects that receive funding from EPA:
State and local governments receiving
EPA assistance for environmental
monitoring projects must complete a
quality assurance program plan
acceptable to the award official.
Guidance for producing the program
plan is contained in USEPA (1983d).
Environmental monitoring projects
that receive EPA funding must file a
quality assurance project plan, or
QAPP, (40 CFR 30.503), the purpose
of which is to ensure quality of a spe-
cific project. The QAPP describes
quality assurance practices designed
to produce data of quality sufficient
to meet project objectives. Guidance
for producing the QAPP (formerly
termed the QAPjP) is contained in
USEPA (1983e). The plan must
address the following items:
Title of project and names of
principal investigators.
Table of contents.
Project description.
Project organization and QA/QC
responsibility.
Quality assurance objectives and
criteria for determining precision,
accuracy, completeness, representa-
tiveness, and comparability of data.
Sampling procedures.
Sample custody.
Calibration procedures.
Analytical procedures.
Data reduction, validation, and
reporting.
Internal quality control checks.
Performance and system audits.
Preventive maintenance proce-
dures.
Specific routine procedures to
assess data precision, accuracy,
representativeness, and compara-
bility.
Corrective action.
Quality assurance reports.
Sample and Analytical Quality Control
The following quality control tech-
niques are useful in assessing sampling
and analytic performance (see also
USEPA 1979b, Horwitz et al. 1994):
Duplicate samples are independent
samples collected in such a manner
that they are equally representative of
the contaminants of interest. Dupli-
Chemical Characteristics
7-73
-------
cate samples, when analyzed by the
same laboratory, provide precision
information for the entire measure-
ment system, including sample
collection, homogeneity, handling,
shipping, storage, preparation, and
analysis.
Split samples have been divided into
two or more portions at some point
in the measurement process. Split
samples that are divided in the field
yield results relating precision to
handling, shipping, storage, prepara-
tion, and analysis. The split samples
may be sent to different laboratories
and subjected to the same measure-
ment process to assess interlaborato-
ry variation. Split samples serve an
oversight function in assessing the
analytical portion of the measure-
ment system, whereas error due to
sampling technique may be estimat-
ed by analyzing duplicate versions of
the same sample.
Spiked samples are those to which a
known quantity of a substance is
added. The results of spiking a sam-
ple in the field are usually expressed
as percent recovery of the added
material. Spiked samples provide a
check of the accuracy of laboratory
and analytic procedures.
Sampling accuracy can be estimated by
evaluating the results obtained from
blanks. The most suitable types of
blanks for this appraisal are equipment,
field, and trip blanks.
Equipment blanks are samples obtained
by running analyte-free water through
sample collection equipment, such as
a bailer, pump, or auger, after decon-
tamination procedures are complet-
ed. These samples are used to deter-
mine whether variation is introduced
by sampling equipment.
Field blanks are made by transferring
deionized water to a sample contain-
er at the sampling site. Field blanks
test for contamination in the deion-
ized water and contamination intro-
duced through the sampling proce-
dure. They differ from trip blanks,
which remain unopened in the field.
Trip blanks test for cross-contamina-
tion during transit of volatile con-
stituents, such as many synthetic
organic compounds and mercury. For
each shipment of sample containers
sent to the analytical laboratory, one
container is filled with analyte-free
water at the laboratory and is sealed.
The blanks are transported to the site
with the balance of the sample con-
tainers and remain unopened.
Otherwise, they are handled in the
same manner as the other samples.
The trip blanks are returned to the
laboratory with the samples and are
analyzed for the volatile constituents.
Field Quality Assurance
Errors or a lack of standardization in
field procedures can significantly de-
crease the reliability of environmental
monitoring data. If required, a quality
assurance project plan should be fol-
lowed for field measurement proce-
dures and equipment. If the QAPP is
not formally required, a plan including
similar material should be developed to
ensure the quality of data collected.
Standard operating procedures should
be followed when available and should
be developed when not.
It is important that quality procedures
be followed and regularly examined.
For example, field meters can provide
erroneous values if they are not regu-
larly calibrated and maintained.
Reagent solutions and probe electrolyte
solutions have expiration periods and
should be refreshed periodically.
7-74
Chapter 7: Analysis of Corridor Condition
-------
7.D Biological Characteristics
Nearly all analytical procedures for as-
sessing the condition of biological re-
sources can be used in stream corridor
restoration. Such procedures differ,
however, in their scale and focus and in
the assumptions, knowledge, and effort
required to apply them. These proce-
dures can be grouped into two broad
classessynthetic measures of system
condition and analyses based on how
well the system satisfies the life history
requirements of target species or species
groups.
The most important difference between
these classes is the logic of how they are
applied in managing or restoring a
stream corridor system. This chapter fo-
cuses on metrics of biological condi-
tions and does not describe, for
example, actual field methods for
counting organisms.
Synthetic Measures of System
Condition
Synthetic measures of system condition
summarize some aspect of the struc-
tural or functional status of a system at
a particular point in time. Complete
measurement of the state of a stream
corridor system, or even a complete
census of all of the species present, is
not feasible. Thus, good indicators of
system condition are efficient in the
sense that they summarize the health of
the overall system without having to
measure everything about the system.
Use of indicators of system condition in
management or restoration depends
completely on comparison to values of
the indicator observed in other systems
or at other times. Thus, the current
value of an indicator for a degraded
stream corridor can be compared to a
previously measured preimpact value
for the corridor, a desired future value
for the corridor, a value observed at an
"unimpacted" reference site, a range of
values observed in other systems, or a
normative value for that class of stream
corridors in a stream classification sys-
tem. However, the indicator itself and
the analysis that establishes the value
of the indicator provide no direct infor-
mation about what has caused the sys-
tem to have a particular value for the
indicator.
Deciding what to change in the system
to improve the value of the indicator
depends on a temporal analysis in
which observed changes in the indica-
tor in one system are correlated with
various management actions or on a
spatial analysis in which values of the
indicator in different systems are corre-
lated with different values of likely con-
trolling variables. In both cases, no
more than a general empirical correla-
tion between specific causal factors and
the indicator variable is attempted.
Thus, management or restoration based
on synthetic measures of system condi-
tion relies heavily on iterative monitor-
ing of the indicator variable and trial
and error, or adaptive management, ap-
proaches. For example, an index of
species composition based on the pres-
ence or absence of a set of sensitive
species might be generally correlated
with water quality, but the index itself
provides no information on how water
quality should be improved. However,
the success of management actions in
improving water quality could be
tracked and evaluated through iterative
measurement of the index.
Synthetic measures of system condition
vary along a number of important di-
mensions that determine their applica-
bility. In certain situations, single
species might be good indicators of
Biological Characteristics
7-75
-------
Stream Visual Assessment Protocol
This is another assessment tool that provides a basic
level of stream health evaluation. It is intended to be the
first level in a four-part hierarchy of assessment protocols
that facilitate planning stream restorations. Scores are
assigned by the planners for the following:
Channel condition
Hydrologic alteration
Riparian zone width
Bank stability
Canopy cover
Water appearance
Nutrient enrichment
Manure presence
Salinity
Barriers to fish movement
Instream fish cover
Pools
Riffle quality
Invertebrate habitat
Macroinvertebrates observed
The planning assessment concludes with narratives of
the suspected causes of observed problems, as well as
recommendations or further steps in the planning
process (USDA-NRCS 1998).
some aspect of a stream corridor sys-
tem; in others, community metrics,
such as diversity, might be more suit-
able. Some indicators incorporate phys-
ical variables, and others do not.
Measurements of processes and rates,
such as primary productivity and chan-
nel meandering rates, are incorporated
into some and not into others. Each of
these dimensions must be evaluated rel-
ative to the objectives of the restoration
effort to determine which, if any, indi-
cator is most appropriate.
Indicator Species
Landres et al. (1988) define an indicator
species as an organism whose character-
istics (e.g., presence or absence, popula-
tion density, dispersion, reproductive
success) are used as an index of attrib-
utes too difficult, inconvenient, or ex-
pensive to measure for other species or
environmental conditions of interest.
Ecologists and management agencies
have used aquatic and terrestrial indica-
tor species for many years as assessment
tools, the late 1970s and early 1980s
being a peak interest period. During that
time, Habitat Evaluation Procedures
(HEP) were developed by the U.S. Fish
and Wildlife Service, and the U.S. Forest
Service's use of management indicator
species was mandated by law with pas-
sage of the National Forest Management
Act in 1976. Since that time, numerous
authors have expressed concern about
the ability of indicator species to meet
the expectations expressed in the above
definition. Most notably, Landres et al.
(1988) critically evaluated the use of
vertebrate species as ecological indica-
tors and suggested that rigorous justifi-
cation and evaluation are needed before
the concept is used. The discussion of
indicator species below is largely based
on their paper.
The Good and Bad of Indicator Species
Indicator species have been used to pre-
dict environmental contamination,
population trends, and habitat quality;
however, their use in evaluating water
quality is not covered in this section.
The assumptions implicit in using indi-
cators are that if the habitat is suitable
for the indicator it is also suitable for
other species (usually in a similar eco-
logical guild) and that wildlife popula-
tions reflect habitat conditions.
However, because each species has
unique life requisites, the relationship
between the indicator and its guild may
7-76
Chapter 7: Analysis of Corridor Condition
-------
not be completely reliable, although the
literature is inconsistent in this regard
(see Riparian Response Guilds subsec-
tion below). It is also difficult to in-
clude all the factors that might limit a
population when selecting a group of
species that an indicator is expected to
represent. For example, similarities in
breeding habitat between the indicator
and its associates might appear to
group species when in fact differences
in predation rates, disease, or winter
habitat actually limit populations.
Some management agencies use verte-
brate indicators to track changes in
habitat condition or to assess the influ-
ence of habitat alteration on selected
species. Habitat suitability indices and
other habitat models are often used for
this purpose, though the metric chosen
to measure a species' response to its
habitat can influence the outcome of
the investigation. As Van Home (1983)
pointed out, density and other abun-
dance metrics may be misleading indi-
cators of habitat quality. Use of
diversity and other indices to estimate
habitat quality also creates problems
when the variation in measures yields
an average value for an index that
might not represent either extreme.
Selecting Indicators
Landres et al. (1988) suggest that if the
decision is made to use indicators, then
several factors are important to consider
in the selection process:
Sensitivity of the species to the envi-
ronmental attribute being evaluated.
When possible, data that suggest a
cause-and-effect relationship are pre-
ferred to correlates (to ensure the
indicator reflects the variable of inter-
est and not a correlate).
Indicator accurately and precisely
responds to the measured effect.
High variation statistically limits the
ability to detect effects. Generalist
species do not reflect change as well
as more sensitive endemics. However,
because specialists usually have lower
populations, they might not be the
best for cost-effective sampling.
When the goal of monitoring is to
evaluate on-site conditions, using
indicators that occur only within the
site makes sense. However, although
permanent residents may better
reflect local conditions, the goal of
many riparian restoration efforts is to
provide habitat for neotropical
migratory birds. In this case, resi-
dents such as cardinals or woodpeck-
ers might not serve as good indica-
tors for migrating warblers.
Size of the species home range. If
possible, the home range should be
larger than that of other species in
the evaluation area. Management
agencies often are forced to use high-
profile game or threatened and
endangered species as indicators.
Game species are often poor indica-
tors simply because their populations
are highly influenced by hunting
mortality, which can mask environ-
mental effects. Species with low pop-
ulations or restrictions on sampling
methods, such as threatened and
endangered species, are also poor
indicators because they are difficult
to sample adequately, often due to
budget constraints. For example,
Verner (1986) found that costs to
detect a 10 percent change in a ran-
domly sampled population of pileat-
ed woodpeckers would exceed a mil-
lion dollars per year.
Response of an indicator species to
an environmental stressor cannot be
expected to be consistent across vary-
ing geographic locations or habitats
without corroborative research.
Biological Characteristics
7-77
-------
Riparian Response Guilds
Vertebrate response guilds as indicators
of restoration success in riparian ecosys-
tems may be a valuable monitoring tool
but should be used with the same cau-
tions presented above. Croonquist and
Brooks (1991) evaluated the effects of
anthropogenic disturbances on small
mammals and birds along Pennsylvania
waterways. They evaluated species in
five different response guilds, including
wetland dependency, trophic level,
species status (endangered, recreational,
native, exotic), habitat specificity, and
seasonality (birds).
They found that community coefficient
indices were better indicators than
species richness. The habitat specificity
and seasonality response guilds for birds
were best able to distinguish those
species sensitive to disturbance from
those which were not affected or were
benefited. Neotropical migrants and
species with specific habitat require-
ments were the best predictors of distur-
bance. Edge and exotic species were
greater in abundance in the disturbed
habitats and might serve as good indica-
tors there. Seasonality analysis showed
migrant breeders were more common in
undisturbed areas, which, as suggested
by Verner (1984), indicates the ability of
guild analysis to distinguish local im-
pacts. Mammalian response guilds did
not exhibit any significant sensitivity to
disturbance and were considered unsuit-
able as indicators.
In contrast, Mannan et al. (1984)
found that in only one of the five avian
guilds tested was the density of birds
consistent across managed and undis-
turbed forests. In other words, popula-
tion response to restoration might not
be consistent across different indicator
guilds. Also, periodically monitoring
restoration initiatives is necessary to
document when, during the recovery
stage, the more sensitive species out-
compete generalists.
Aquatic Invertebrates
Aquatic invertebrates have been used as
indicators of stream and riparian health
for many years. Perhaps more than
other taxa, they are closely tied to both
aquatic and riparian habitat. Their life
cycles usually include periods in and
out of the water, with ties to riparian
vegetation for feeding, pupation, emer-
gence, mating, and egg laying (Erman
1991).
It is often important to look at the en-
tire assemblage of aquatic invertebrates
as an indicator group. Impacts to a
stream often decrease diversity but
might increase the abundance of some
species, with the size of the first species
to be affected often larger (Wallace and
Gurtz 1986). In summary, a good indi-
cator species should be low on the food
chain to respond quickly, should have a
narrow tolerance to change, and should
be a native species (Erman 1991).
Diversity and Related Indices
Biological diversity refers to the number
of species in an area or region and in-
cludes a measure of the variety of
species in a community that takes into
account the relative abundance of each
species (Ricklefs 1990). When measur-
ing diversity, it is important to clearly
define the biological objectives, stating
exactly what attributes of the system are
of concern and why (Schroeder and
Keller 1990). Different measures of di-
versity can be applied at various levels
of complexity, to different taxonomic
groups, and at distinct spatial scales.
Several factors should be considered
in using diversity as a measure of sys-
tem condition for stream corridor
restoration.
7-78
Chapter 7: Analysis of Corridor Condition
-------
Levels of Complexity
Diversity can be measured at several
levels of complexitygenetic, popula-
tion/species, community/ecosystem,
and landscape (Noss 1994). There is no
single correct level of complexity to use
because different scientific or manage-
ment issues are focused on different
levels (Meffe et al. 1994). The level of
complexity chosen for a specific stream
corridor restoration initiative should be
determined based on careful considera-
tion of the biological objectives of the
project.
Subsets of Concern
Overall diversity within any given level
of complexity may be of less concern
than diversity of a particular subset of
species or habitats. Measures of overall
diversity include all of the elements of
concern and do not provide informa-
tion about the occurrence of specific el-
ements. For example, measures of
overall species diversity do not provide
information about the presence of indi-
vidual species or species groups of man-
agement concern.
Any important subsets of diversity
should be described in the process of
setting biological objectives. At the
community level, subsets of species of
interest might include native, endemic,
locally rare or threatened, specific
guilds (e.g., cavity users), or taxonomic
groups (e.g., amphibians, breeding
birds, macroinvertebrates). At the terres-
trial landscape level, subsets of diversity
could include forest types or serai stages
(Noss 1994). Thus, for a specific stream
corridor project, measurement of diver-
sity may be limited to a target group of
special concern. In this manner, com-
parison of diversity levels becomes
more meaningful.
Spatial Scale
Diversity can be measured within the
bounds of a single community, across
community boundaries, or in large
areas encompassing many communi-
ties. Diversity within a relatively
homogeneous community is known
as alpha diversity. Diversity between
communities, described as the amount
of differentiation along habitat gradi-
ents, is termed beta diversity. The total
diversity across very large landscapes
is gamma diversity. Noss and Harris
(1986) note that management for
alpha diversity may increase local
species richness, while the regional
landscape (gamma diversity) may be-
come more homogeneous and less
diverse overall. They recommend a
goal of maintaining the regional species
pool in an approximately natural rela-
tive abundance pattern. The specific
size of the area of concern should be
defined when diversity objectives are
established.
Measures of Diversity
Magurran (1988) describes three main
categories of diversity measuresrich-
ness indices, abundance models, and
indices based on proportional abun-
dance. Richness indices are measures
of the number of species (or other
element of diversity) in a specific sam-
pling unit and are the most widely used
indices (Magurran 1988). Abundance
models account for the evenness (equi-
tability) of distribution of species and
fit various distributions to known mod-
els, such as the geometric series, log se-
ries, lognormal, or broken stick. Indices
based on the proportional abundance
of species combine both richness and
evenness into a single index. A variety
of such indices exist, the most common
of which is the Shannon-Weaver diver-
sity index (Krebs 1978):
H = -Zp. loge p.
Biological Characteristics
7-79
-------
where
H = index of species diversity
S = number of species
p. = proportion of total sample
belonging to the ith species
Results of most studies using diversity
indices are relatively insensitive to the
particular index used (Ricklefs 1979).
For example, bird species diversity in-
dices from 267 breeding bird censuses
were highly correlated (r = 0.97) with
simple counts of bird species richness
(Tramer 1969). At the species level, a
simple measure of richness is most
often used in conservation biology
studies because the many rare species
that characterize most systems are gen-
erally of greater interest than the com-
mon species that dominate in diversity
indices and because accurate popula-
tion density estimates are often not
available (Meffe et al. 1994).
Simple measures of species richness,
however, are not sensitive to the actual
species composition of an area. Similar
richness values in two different areas
may represent very different sets of
species. The usefulness of these mea-
sures can be increased by considering
specific subsets of species of most con-
cern, as mentioned above. Magurran
(1988) recommends going beyond the
use of a single diversity measure and ex-
amining the shape of the species abun-
dance distribution as well. Breeding
bird census data from an 18-hectare
(ha) riparian deciduous forest habitat
in Ohio (Tramer 1996) can be used to
illustrate these different methods of
presentation (Figure 7.36). Breeding
bird species richness in this riparian
habitat was 38.
Pielou (1993) recommends the use of
three indices to adequately assess diver-
sity in terrestrial systems:
A measure of plant species diversity.
A measure of habitat diversity.
A measure of local rarity.
Other indices used to measure various
aspects of diversity include vegetation
measures, such as foliage height diver-
sity (MacArthur and MacArthur 1961),
and landscape measures, such as fractal
dimension, fragmentation indices, and
juxtaposition (Noss 1994).
Related Integrity Indices
Karr (1981) developed the Index of Bi-
otic Integrity to assess the diversity and
health of aquatic communities. This
index is designed to assess the present
status of the aquatic community using
fish community parameters related to
species composition, species richness,
and ecological factors. Species composi-
tion and richness parameters may in-
clude the presence of intolerant species,
the richness and composition of spe-
cific species groups (e.g., darters), or the
proportion of specific groups (e.g., hy-
brid individuals). Ecological parameters
may include the proportion of top car-
nivores, number of individuals, or pro-
portion with disease or other
anomalies. Key parameters are devel-
oped for the stream system of interest,
and each parameter is assigned a rating.
The overall rating of a stream is used to
evaluate the quality of the aquatic
biota.
Rapid Bioassessment
Rapid bioassessment techniques are
most appropriate when restoration
goals are nonspecific and broad, such
as improving the overall aquatic com-
munity or establishing a more balanced
and diverse community in the stream
corridor. Bioassessment often refers to
use of biotic indices or composite
analyses, such as those used by Ohio
EPA (1990), and rapid bioassessment
protocols (RBP), such as those docu-
mented by Plafkin et al. (1989). Ohio
7-80
Chapter 7: Analysis of Corridor Condition
-------
EPA evaluates biotic integrity by using
an invertebrate community index (ICI)
that emphasizes structural attributes of
invertebrate communities and com-
pares the sample community with a ref-
erence or control community. The ICI is
based on 10 metrics that describe differ-
ent taxonomic and pollution tolerance
relationships within the macroinverte-
brate community. The RBP established
by USEPA (Plafkin et al. 1989) were de-
veloped to provide states with the tech-
nical information necessary for
conducting cost-effective biological as-
sessments. The RBP are divided into five
sets of protocols (RBP I to V), three for
macroinvertebrates and two for fish
(Table 7.8).
Algae
Although not detailed by Plafkin et al.
(1989), algal communities are useful
for bioassessment. Algae generally have
short life spans and rapid reproduction
rates, making them useful for evaluating
short-term impacts. Sampling impacts
are minimal to resident biota, and col-
lection requires little effort. Primary
productivity of algae is affected by phys-
ical and chemical impairments. Algal
communities are sensitive to some pol-
lutants that might not visibly affect
other aquatic communities. Algal com-
munities can be examined for indicator
species, diversity indices, taxa richness,
community respiration, and coloniza-
tion rates. A variety of nontaxonomic
evaluations, such as biomass and
chlorophyll, may be used and are sum-
marized in Weitzel (1979). Rodgers et
al. (1979) describe functional measure-
ments of algal communities, such as
primary productivity and community
respiration, to evaluate the effects of
nutrient enrichment.
Although collecting algae in streams re-
quires little effort, identifying for met-
rics, such as diversity indices and taxa
1 Species
Species
^^^^^^^^^^^1 Sequence 1
20 p
15 -
O)
u
c
re
-010-
3
5 -
0
III
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
American robin
House wren
Gray catbird
Song sparrow
Northern cardinal
Baltimore oriole
Warbling vireo
Wood thrush
Common grackle
Eastern wood-pewee
Red-eyed vireo
Indigo bunting
Red-winged blackbird
Mourning dove
Northern flicker
Blue jay
Tufted titmouse
White-breasted nuthatch
American redstart
Rose-breasted grosbeak
Downy woodpecker
Great crested flycatcher
Black-capped chickadee
Carolina wren
European starling
Yellow warbler
Brown-headed cowbird
American goldfinch
Wood duck
Ruby-throated hummingbird
Red-bellied woodpecker
Hairy woodpecker
Tree swallow
Blue-gray gnatcatcher
Prothonotary warbler
Common yellowthroat
Eastern phoebe
N. rough-winged swallow
Abundance
in 18-ha Plot 1
18.5
13
10.5
9.5
7.5
7
6
4.5
4.5
4
4
4
4
3
3
3
3
3
3
3
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
Illllllllllllllll
, ,
i
i i i i
I
10 15 20 25 30 35 40
Species Sequence
Figure 7.36: Breeding bird census data. Species
abundance curve in a riparian deciduous forest
habitat.
Source: Tramer 1996.
Biological Characteristics
7-81
-------
Table 7.8: Five tiers of the rapid bioassessment protocols. RBPs are used to conduct cost-effective
biological assessments,
Source: Plafkin et al. 1989.
Level
or Tier
1
II
III
IV
V
(Organism
Group
Benthk
invertebrates
Benthic
invertebrates
Benthic
invertebrates
Fish
Fish
I Relative Level of Effort
Low; 1-2 hr per site (no
standardized sampling)
Intermediate; 1.5-2.5 hr
per site (all taxonomy
performed in field)
Most rigorous; 3-5 hr per
site (2-3 hr of total are for
lab taxonomy)
Low; 1-3 hr per site (no
fieldwork involved)
Most rigorous; 2-7 hr per
site (1-2 hr per site are for
data analysis)
I Level of Taxonomy/
Where Performed
Order, family/field
Family/field
Genus or
species/laboratory
Not applicable
Species/field
I Level of Expertise
Required
One highly-trained
biologist
One highly-trained biologist
and one technician
One highly-trained biologist
and one technician
One highly-trained
biologist
One highly-trained biologist
and 1-2 technicians
richness, may require considerable ef-
fort. A great deal of effort may be ex-
pended to document diurnal and
seasonal variations in productivity.
Benthic Macroinvertebrates
The intent of the benthic rapid
bioassessment is to evaluate overall bio-
logical condition, optimizing the use of
the benthic community's capacity to re-
flect integrated environmental effects
over time. Using benthic macroinverte-
brates is advantageous for the following
reasons:
They are good indicators of localized
conditions.
They integrate the effects of short-
term environmental variables.
Degraded conditions are easily
detected.
Sampling is relatively easy.
They provide food for many fish of
commercial or recreational impor-
tance.
Macroinvertebrates are generally
abundant.
Many states already have background
data.
As indicated above, the RBP are divided
into three sets of protocols (RBP I to
III) for macroinvertebrates. RBP I is a
"screening" or reconnaissance-level
analysis used to discriminate obviously
impaired and nonimpaired sites from
potentially affected areas requiring fur-
ther investigation. RBP II and III use a
set of metrics based on taxon tolerance
and community structure similar to the
ICI used by the state of Ohio. Both are
more labor-intensive than RBP I and in-
corporate field sampling. RBP II uses
family-level taxonomy to determine the
following set of metrics used in describ-
ing the biotic integrity of a stream:
Taxa richness.
Hilsenhoff biotic index (Hilsenhoff
1988).
Ratio of scrapers to filtering collectors.
Ratio of Ephemeroptera/Plecoptera/
Trichoptera (EPT) and chironomid
abundances.
Percent contribution of dominant
taxa.
EPT index.
Community similarity index.
Ratio of shredders to total number of
individuals.
7-82
Chapter 7: Analysis of Corridor Condition
-------
RBP III further defines the level of bi-
otic impairment and is essentially an
intensified version of RBP II that uses
species-level taxonomy. As with ICI, the
RBP metrics for a site are compared to
metrics from a control or reference site.
Fish
Hocutt (1981) states "perhaps the most
compelling ecological factor is that
structurally and functionally diverse fish
communities both directly and indi-
rectly provide evidence of water quality
in that they incorporate all the local en-
vironmental perturbations into the sta-
bility of the communities themselves."
The advantages of using fish as bioindi-
cators are as follows:
They are good indicators of long-
term effects and broad habitat condi-
tions.
Fish communities represent a variety
of trophic levels.
Fish are at the top of the aquatic
food chain and are consumed by
humans.
Fish are relatively easy to collect and
identify.
Water quality standards are often
characterized in terms of fisheries.
Nearly one-third of the endangered
vertebrate species and subspecies in
the United States are fish.
The disadvantages of using fish as
bioindicators are as follows:
The cost.
Statistical validity may be hard to
attain.
It is difficult to interpret findings.
Electrofishing is the most commonly
used field technique. Each collecting
station should be representative of the
study reach and similar to other reaches
sampled; effort between reaches should
be equal. All fish species, not just game
species, should be collected for the fish
community assessment (Figure 7.37).
Karr et al. (1986) used 12 biological
metrics to assess biotic integrity using
taxonomic and trophic composition
and condition and abundance of fish.
Although the Index of Biological In-
tegrity (IBI) developed by Karr was de-
signed for small midwestern streams, it
has been modified for many regions of
the country and for use in large rivers
(see Plafkinetal. 1989).
Establishing a Standard of
Comparison
With stream restoration activities, it is
important to select a desired end condi-
tion for the proposed management ac-
tion. A predetermined standard of
comparison provides a benchmark
against which to measure progress. For
example, if the chosen diversity mea-
sure is native species richness, the stan-
dard of comparison might be the
maximum expected native species rich-
ness for a defined geographic area and
time period.
Figure 7.37: Fish samples. Water quality
standards are often characterized in terms
of fisheries.
Biological Characteristics
7-83
-------
Historical conditions in the region
should be considered when establishing
a standard of comparison. If current
conditions in a stream corridor are
degraded, it may be best to establish
the standard at a period in the past that
represented more natural or desired
conditions. Knopf (1986) notes that for
certain western streams, historical diver-
sity might have been less than current
due to changes in hydrology and en-
croachment of native and exotic ripar-
ian vegetation in the floodplain. Thus,
it is important to agree on what condi-
tions are desired prior to establishing
the standard of comparison. In addi-
tion, the geographic location and size
of the area should be considered. Pat-
terns of diversity vary with geographic
location, and larger areas are typically
more diverse than smaller areas.
The IBI is scaled to a standard of com-
parison determined through either pro-
fessional judgment or empirical data,
and such indices have been developed
for a variety of streams (Leonard and
Orth 1986, Bramblett and Fausch 1991,
Lyons et al. 1996).
Evaluating the Chosen Index
For a hypothetical stream restoration
initiative, the following biological diver-
sity objective might be developed. As-
sume that a primary concern in the area
is conserving native amphibian species
and that 30 native species of amphib-
ians have been known to occur histori-
cally in the 386m2 watershed. The
objective could be to manage the
stream corridor to provide and main-
tain suitable habitat for the 30 native
amphibian species.
Stream corridor restoration efforts must
be directed toward those factors that
can be managed to increase diversity to
the desired level. Those factors might be
the physical and structural features of
the stream corridor or possibly the pres-
ence of an invasive species in the com-
munity. Knowledge of the important
factors can be obtained from existing
literature and from discussions with
local and regional experts.
Diversity can be measured directly or
predicted from other information. Di-
rect measurement requires an actual in-
ventory of the element of diversity, such
as counting the amphibian species in
the study area. The IBI requires sam-
pling fish populations to determine the
number and composition of fish
species. Measures of the richness of a
particular animal group require counts.
Determining the number of species in a
community is best accomplished with a
long-term effort because there can be
much variation over short periods. Vari-
ation can arise from observer differ-
ences, sampling design, or temporal
variation in the presence of species.
Direct measures of diversity are most
helpful when baseline information is
available for comparing different sites.
It is not possible, however, to directly
measure certain attributes, such as
species richness or the population level
of various species, for various future
conditions. For example, the IBI cannot
be directly computed for a predicted
stream corridor condition, following
management action.
Predictions of diversity for various fu-
ture conditions, such as with restora-
tion or management, require the use of
a predictive model. Assume the diver-
sity objective for a stream corridor
restoration effort is to maximize native
amphibian species richness. Based on
knowledge of the life history of the
species, including requirements for
habitat, water quality, or landscape
configuration, a plan can be developed
to restore a stream corridor to meet
these needs. The plan could include a
set of criteria or a model to describe
the specific features that should be
7-84
Chapter 7: Analysis of Corridor Condition
-------
included to maximize amphibian rich-
ness. Examples of indirect methods to
assess diversity include habitat models
(Schroeder and Allen 1992, Adamus
1993) and cumulative impact assess-
ment methods (Gosselink et al. 1990,
Brooks etal. 1991).
Predicting diversity with a model is
generally more rapid than directly mea-
suring diversity. In addition, predictive
methods provide a means to analyze
alternative future conditions before im-
plementing specific restoration plans.
The reliability and accuracy of diversity
models should be established before
their use.
Classification Systems
Classification is an important compo-
nent of many of the scientific disci-
plines relevant to stream
corridorshydrology, geomorphology,
limnology, plant and animal ecology.
Table 7.9 lists some of the classification
systems that might be useful in identify-
ing and planning riverine restoration
activities. It is not the intent of this sec-
tion to exhaustively review all classifica-
tion schemes or to present a single rec-
ommended classification system. Rather,
we focus on some of the principal dis-
tinctions among classification systems
and factors to consider in the use of
classification systems for restoration
planning, particularly in the use of a
classification system as a measure of
biological condition. It is likely that
multiple systems will be useful in most
actual riverine restoration programs.
The common goal of classification
systems is to organize variation. Impor-
tant dimensions in which riverine clas-
sification systems differ include the
following:
Geographic domain. The range of sites
being classified varies from rivers of
the world to local differences in the
composition and characteristics of
patches within one reach of a single
river.
Variables considered. Some classifica-
tions are restricted to abiotic vari-
Table 7.9: Selected riverine and riparian classi-
fication systems. Classification systems are
useful in characterizing biological conditions.
Classification System
Riparian vegetation of Yampa,
San Miguel/Dolores River Basins
Riparian and scrubland
communities of Arizona and
New Mexico
Classification of Montana
riparian and wetland sites
Integrated riparian evaluation
guide
Streamflow cluster analysis
River Continuum
World-wide stream
classification
Rosgen's river classification
Hydrogeomorphic wetland
classification
Recovery classes following
channelization
Subject
Plant communities
Plant communities
Plant communities
Hydrology, geomorphology, soils,
vegetation
Hydrology with correlations to
fish and invertebrates
Hydrology, stream order, water
chemistry, aquatic communities
Hydrology, water chemistry,
substrate, vegetation
Hydrology, geomorphology:
stream and valley types
Hydrology, geomorphology,
vegetation
Hydrology, geomorphology,
vegetation
Geographic I Citation
Domain
Colorado
Arizona and
New Mexico
Montana
Kittel and Lederer
(1993)
Szaro(1989)
Hansen et al.
(1995)
Intermountain U.S. Forest Service
(1992)
National
Pott and Ward
(1989)
International, Vannote et al.
national (1980)
International Pennak(1971)
National Rosgen (1996)
National Brinson (1993)
Tennessee Hupp (1992)
Biological Characteristics
7-85
-------
ables of hydrology, geomorphology,
and aquatic chemistry. Other com-
munity classifications are restricted
to biotic variables of species compo-
sition and abundance of a limited
number of taxa. Many classifications
include both abiotic and biotic vari-
ables. Even purely abiotic classifica-
tion systems are relevant to biologi-
cal evaluations because of the impor-
tant correlations (e.g., the whole con-
cept of physical habitat) between abi-
otic structure and community com-
position.
Incorporation of temporal relations.
Some classifications focus on
describing correlations and similari-
ties across sites at one, perhaps ideal-
ized, point in time. Other classifica-
tions identify explicit temporal tran-
sitions among classes, for example,
succession of biotic communities or
evolution of geomorphic landforms.
Focus on structural variation or func-
tional behavior. Some classifications
emphasize a parsimonious descrip-
tion of observed variation in the clas-
sification variables. Others use classi-
fication variables to identify types
with different behaviors. For exam-
ple, a vegetation classification can be
based primarily on patterns of
species co-occurrence, or it can be
based on similarities in functional
effect of vegetation on habitat value.
The extent to which management alter-
natives or human actions are explicitly
considered as classification variables.
To the extent that these variables are
part of the classification itself, the
classification system can directly
predict the result of a management
action. For example, a vegetation
classification based on grazing in-
tensity would predict a change from
one class of vegetation to another
class based on a change in grazing
management.
Use of Classification Systems in
Restoring Biological Conditions
Restoration efforts may apply several
national and regional classification sys-
tems to the riverine site or sites of inter-
est because these are efficient ways to
summarize basic site description and
inventory information and they can fa-
cilitate the transference of existing in-
formation from other similar systems.
Most classification systems are generally
weak at identifying causal mechanisms.
To varying degrees, classification sys-
tems identify variables that efficiently
describe existing conditions. Rarely do
they provide unequivocal assurance
about how variables actually cause the
observed conditions. Planning efficient
and effective restoration actions gener-
ally requires a much more mechanistic
analysis of how changes in controllable
variables will cause changes toward de-
sired values of response variables. A sec-
ond limitation is that application of a
classification system does not substitute
for goal setting or design. Comparison
of the degraded system to an actual
unimpacted reference site, to the ideal
type in a classification system, or to a
range of similar systems can provide a
framework for articulating the desired
state of the degraded system. However,
the desired state of the system is a
management objective that ultimately
comes from outside the classification of
system variability.
Analyses of Species
Requirements
Analyses of species requirements in-
volve explicit statements of how vari-
ables interact to determine habitat or
how well a system provides for the life
requisites of fish and wildlife species.
Complete specification of relations be-
tween all relevant variables and all
species in a stream corridor system is
not possible. Thus, analyses based on
7-86
Chapter 7: Analysis of Corridor Condition
-------
species requirements focus on one or
more target species or groups of species.
In a simple case, this type of analysis
may be based on an explicit statement
of the physical factors that distinguish
good habitat for a species (places where
it is most likely to be found or where it
best reproduces) from poor habitat
(places where it is unlikely to be found
or reproduces poorly). In more compli-
cated cases, such approaches incorpo-
rate variables beyond those of purely
physical habitat, including other species
that provide food or biotic structure,
other species as competitors or preda-
tors, or spatial or temporal patterns of
resource availability.
Analyses based on species requirements
differ from synthetic measures of sys-
tem condition in that they explicitly in-
corporate relations between "causal"
variables and desired biological attri-
butes. Such analyses can be used di-
rectly to decide what restoration actions
will achieve a desired result and to eval-
uate the likely consequences of a pro-
posed restoration action. For example,
an analysis using the habitat evaluation
procedures might identify mast produc-
tion (the accumulation of nuts from a
productive fruiting season which serves
as a food source for animals) as a factor
limiting squirrel populations. If squir-
rels are a species of concern, at least
some parts of the stream restoration ef-
fort should be directed toward increas-
ing mast production. In practice, this
logical power is often compromised by
incomplete knowledge of the species
habitat requirements.
The complexity of these methods varies
along a number of important dimen-
sions, including prediction of habitat
suitability versus population numbers,
analysis for a single place and single
time versus a temporal sequence of
spatially complex requirements, and
analysis for a single target species versus
a set of target species involving trade-
offs. Each of these dimensions must be
carefully considered in selecting an
analysis procedure appropriate to the
problem at hand.
The Habitat Evaluation
Procedures (HEP)
Habitat evaluation procedures (HEP)
can be used for several different types of
habitat studies, including impact assess-
ment, mitigation, and habitat manage-
ment. HEP provides information for
two general types of habitat compar-
isonsthe relative value of different
areas at the same point in time and the
relative value of the same area at differ-
ent points in time. Potential changes in
wildlife (both aquatic and terrestrial)
habitat due to proposed projects are
characterized by combining these two
types of comparisons.
Basic Concepts
HEP is based on two fundamental eco-
logical principleshabitat has a defin-
able carrying capacity, or suitability, to
support or produce wildlife popula-
tions (Fretwell and Lucas 1970), and
the suitability of habitat for a given
wildlife species can be estimated using
measurements of vegetative, physical,
and chemical traits of the habitat. The
suitability of a habitat for a given
species is described by a habitat suit-
ability index (HSI) constrained between
0 (unsuitable habitat) and 1 (optimum
habitat). HSI models have been devel-
oped and published by the U.S. Fish
and Wildlife Service (Schamberger et al.
1982; Terrell and Carpenter, in press),
and USFWS (1981) provides guidelines
for use in developing HSI models for
specific projects. HSI models can be
developed for many of the previously
described metrics, including species,
guilds, and communities (Schroeder
andHaire 1993).
Biological Characteristics
7-87
-------
The fundamental unit of measure in
HEP is the Habitat Unit, computed as
follows:
HU = AREA x HSI
where HU is the number of habitat
units (units of area), AREA is the areal
extent of the habitat being described
(units of area), and HSI is the index of
suitability of the habitat (unitless).
Conceptually, an HU integrates the
quantity and quality of habitat into a
single measure, and one HU is equiva-
lent to one unit of optimal habitat.
Use of HEP to Assess Habitat Changes
HEP provides an assessment of the net
change in the number of HUs attribut-
able to a proposed future action, such
as a stream restoration initiative. A HEP
application is essentially a two-step
processcalculating future HUs for a
particular project alternative and calcu-
lating the net change as compared to a
base condition.
The steps involved in using and apply-
ing HEP to a management project are
outlined in detail in USFWS (1980a).
However, some early planning decisions
often are given little attention although
they may be the most important part of
a HEP study. These initial decisions in-
clude forming a study team, defining
the study boundaries, setting study ob-
jectives, and selecting the evaluation
species. The study team usually consists
of individuals representing different
agencies and viewpoints. One member
of the team is generally from the lead
project planning agency and other
members are from resources agencies
with an interest in the resources that
would be affected.
One of the first tasks for the team is to
delineate the study area boundaries.
The study area boundaries should be
drawn to include any areas of direct im-
pact, such as a flood basin for a new
reservoir, and any areas of secondary
impact, such as a downstream river
reach that might have an altered flow,
increased turbidity, or warmer tempera-
ture, or riparian or upland areas subject
to land use changes as a result of an in-
creased demand on recreational lands.
Areas such as an upstream spawning
ground that are not contiguous to the
primary impact site also might be af-
fected and therefore should be included
in the study area.
The team also must establish project
objectives, an often neglected aspect of
project planning. Objectives should
state what is to be accomplished in the
project and specify an endpoint to the
project. An integral aspect of objective
setting is selecting evaluation species,
the specific wildlife resources of con-
cern for which HUs will be computed
in the HEP analysis. These are often in-
dividual species, but they do not have
to be. Depending on project objectives,
species' life stages (e.g., juvenile
salmon), species' life requisites (e.g.,
spawning habitat), guilds (e.g., cavity-
nesting birds), or communities (e.g.,
avian richness in riparian forests) can
be used.
Instream Flow Incremental
Methodology
The Instream Flow Incremental
Methodology (IFIM) is an adaptive sys-
tem composed of a library of models
that are linked to describe the spatial
and temporal habitat features of a given
river. IFIM is described in Chapter 5
under Supporting Analysis for Selecting
Restoration Alternatives.
Physical Habitat Simulation
The Physical Habitat Simulation
(PHABSIM) model was designed by the
U.S. Fish and Wildlife Service primarily
for instream flow analysis (Bovee
1982). It represents the habitat evalua-
7-88
Chapter 7: Analysis of Corridor Condition
-------
tion component of a larger instream
flow incremental methodology for in-
corporating fish habitat consideration
into flow management, presented in
Chapter 5. PHABSIM is a collection of
computer programs that allows evalua-
tion of available habitat within a study
reach for various life stages of different
fish species. The two basic components
of the model are hydraulic simulation
(based on field-measured cross-sec-
tional data) and several standard hy-
draulic methods for predicting water
surface elevations and velocities at un-
measured discharges (e.g., stage vs. dis-
charge relations, Manning's equation,
step-backwater computations). Habitat
simulation integrates species and life-
stage-specific habitat suitability curves
for water depth, velocity, and substrate
with the hydraulic data. Output is a
plot of weighted usable area (WUA)
against discharge for the species and life
stages of interest. (Figure 7.38)
The stream hydraulic component pre-
dicts depths and water velocities at un-
observed flows at specific locations on a
cross section of a stream. Field measure-
ments of depth, velocity, substrate ma-
terial, and cover at specific sampling
points on a cross section are taken at
different observable flows. Hydraulic
measurements, such as water surface el-
evations, also are collected during the
field inventory. These data are used to
calibrate the hydraulic simulation mod-
els. The models then are used to predict
depths and velocities at flows different
from those measured.
The habitat component weights each
stream cell using indices that assign a
relative value between 0 and 1 for each
habitat attribute (depth, velocity, sub-
strate material, cover), indicating how
suitable that attribute is for the life
stage under consideration. These at-
tribute indices are usually termed habi-
tat suitability indices and are developed
from direct observations of the attrib-
utes used most often by a life stage,
from expert opinion about what the life
requisites are, or a combination. Vari-
ous approaches are taken to factor as-
sorted biases out of these suitability
data, but they remain indices that are
used as weights of suitability. In the last
step of the habitat component, hy-
draulic estimates of depth and velocity
at different flow levels are combined
with the suitability values for those at-
tributes to weight the area of each cell
at the simulated flows. The weighted
values for all cells are summed to pro-
duce the WUA.
There are many variations on the basic
approach outlined above, with specific
analyses tailored for different water
management phenomena (such as hy-
dropeaking and unique spawning habi-
tat needs), or for special habitat needs
(such as bottom velocity instead of
mean column velocity) (Milhous et al.
1989). However, the fundamentals of
hydraulic and habitat modeling remain
the same, resulting in a WUA versus dis-
charge function. This function should
be combined with the appropriate hy-
drologic time series (water availability)
to develop an idea of what life states
might be affected by a loss or gain of
available habitat and at what time of
the year. Time series analysis plays this
role and also factors in any physical
and institutional constraints on water
management so that alternatives can be
evaluated (Milhous et al. 1990).
Several things must be remembered
about PHABSIM. First, it provides an
index to microhabitat availability; it is
not a measure of the habitat actually
used by aquatic organisms. It can be
used only if the species under consider-
ation exhibit documented preferences
for depth, velocity, substrate material,
cover, or other predictable microhabitat
attributes in a specific environment of
REVERSE
Review Chapter
5's Supporting
Analysis for
Selecting
Restoration
Alternatives
Biological Characteristics
7-89
-------
A. Site-Specific Microhabitat Data
cross section B
V2 V3 velocity
iD2D3.. dePth
cover
area
B. Habitat
Suitability 0.8
Criteria _ 0 6
1/1
0.4
1.0
0.8
_ 0.6
0.4
0.2
(
0.2
\
-
°0 1 234
Velocity (ft/sec)
; _
L I
\
-
-
V
, / \
) 1 23401 234
Depth (ft) Cover
C. Seasonal Relation Between Discharge and
Microhabitat for Each Life Stage
100,000
Discharge
100
Figure 7.38: Conceptualization of how PHAB-
SIM calculates habitat values as a function of
discharge. A. First, depth (Di), velocity (Vi),
cover conditions (Ci), and area (Ai) are mea-
sured or simulated for a given discharge. B.
Suitability index (SI) criteria are used to weight
the area of each cell for the discharge. The
habitat values for all cells in the study reach
are summed to obtain a single habitat value
for the discharge. C. The procedure is repeated
for a range of discharges.
Modified from Nestler et al. 1989.
competition and predation. The typical
application of PHABSIM assumes rela-
tively steady flow conditions such that
depths and velocities are comparably
stable within the chosen time step.
PHABSIM does not predict the effects of
flow on channel change. Finally, the
field data and computer analysis re-
quirements can be relatively large.
Two-dimensional Flow Modeling
Concern about the simplicity of the
one-dimensional hydraulic models used
in PHABSIM has led to current research
interest in the use of more sophisticated
two-dimensional hydraulic models to
7-90
Chapter 7: Analysis of Corridor Condition
-------
simulate physical conditions of depth
and velocity for use in fish habitat
analysis. A two-dimensional hydraulic
model can be spatially adjusted to rep-
resent the scale of aquatic habitat and
the variability of other field data. For
example, the physical relationship be-
tween different aquatic habitat types is
often a key parameter when considering
fish habitat use. The spatial nature of
two-dimensional flow modeling allows
for the analysis of these relationships.
The model can also consider the drying
and wetting of intermittent stream
channels.
Leclerc et al. (1995) used two-dimen-
sional flow modeling to study the effect
of a water diversion on the habitat of
juvenile Atlantic salmon (Salmo solar)
in the Moisie River in Quebec, Canada.
Average model error was reduced when
compared with traditional one-dimen-
sional models. Output from the two-di-
mensional modeling was combined
with habitat suitability indexes with fi-
nite element calculation techniques.
Output from the analysis included
maps displaying the spatial distribution
of depth, velocity, and habitat suitabil-
ity intervals.
Physical data collection for this model-
ing tool is intensive. Channel contour
and bed material mapping is required
along with discharge relationships and
the upstream and downstream bound-
aries of each study reach. Velocity and
water-surface measurements for various
discharges are required for model cali-
bration. Two-dimensional modeling
does not address all of the issues related
to hydrodynamics and flow modeling.
Mobile bed systems and variability in
Manning's coefficient are still problem-
atic using this tool (Leclerc et al. 1995).
Moderate to large rivers with a stable
bedform are most suited to this
methodology.
Riverine Community Habitat
Assessment and Restoration
Concept Model (RCHARC)
Another modeling approach to aquatic
habitat restoration is the Riverine Com-
munity Habitat Assessment and
Restoration (RCHARC) concept. This
model is based on the assumption that
aquatic habitat in a restored stream
reach will best mimic natural condi-
tions if the bivariate frequency distribu-
tion of depth and velocity in the subject
channel is similar to a reference reach
with good aquatic habitat. Study site
and reference site data can be measured
or calculated using a computer model.
The similarity of the proposed design
and reference reach is expressed with
three-dimensional graphs and statistics
(Nestler et al. 1993, Abt 1995).
RCHARC has been used as the primary
tool for environmental analysis on
studies of flow management for the
Missouri River and the Alabama-Coosa-
Tallapoosa Apalachicola-Chatta-
hoochee-Flint Basin.
Time Series Simulations
A relatively small number of applica-
tions have been made of time series
simulations of fish population or indi-
vidual fish responses to riverine habitat
changes. Most of these have used
PHABSIM to accomplish hydraulic
model development and validation and
hydraulic simulation, but some have
substituted time-series simulations of
individual or population responses for
habitat suitability curve development
and validation, and habitat suitability
modeling. PHABSIM quantifies the rela-
tionship of hydraulic estimates (depth
and velocity) and measurements (sub-
strate and cover) with habitat suitability
for target fish and invertebrate life
stages or water-related recreation suit-
ability. It is useful when relatively
steady flow is the major determinant
Biological Characteristics
7-91
-------
controlling riverine resources. Use of
PHABSIM is generally limited to river
systems in which dissolved oxygen, sus-
pended sediment, nutrient loading,
other chemical aspects of water quality,
and interspecific competition do not
place the major limits on populations
of interest. These limitations to the use
of PHABSIM can be abated or removed
with models that simulate response of
individual fish or fish populations.
Individual-based Models
The Electric Power Research Institute
(EPRI) program on compensatory
mechanisms in fish populations
(CompMech) has the objective of im-
proving predictions of fish population
response to increased mortality, loss of
habitat, and release of toxicants (EPRI
1996). This technique has been applied
by utilities and resource management
agencies in assessments involving direct
mortality due to entrainment, impinge-
ment, or fishing; instream flow; habitat
alteration (e.g., thermal discharge,
water-level fluctuations, water diver-
sions, exotic species); and ecotoxicity.
Compensation is defined as the capac-
ity of a population to self-mitigate de-
creased growth, reproduction, or
survival of some individuals in the pop-
ulation by increased growth, reproduc-
tion, or survival of the remaining
individuals. The CompMech approach
over the past decade has been to repre-
sent in simulation models the processes
underlying daily growth, reproduction,
and survival of individual fish (hence
the classification of individual-based
models) and then to aggregate over in-
dividuals to the population level.
The models can be used to make short-
term predictions of survival, growth,
habitat utilization, and consumption
for critical life stages. For the longer
term, the models can be used to project
population abundance through time to
assess the risk that abundance will fall
below some threshold requiring mitiga-
tion. For stream situations, several
CompMech models have been devel-
oped that couple the hydraulic simula-
tion method of PHABSIM directly with
an individual-based model of reproduc-
tion and young-of-year dynamics,
thereby eliminating reliance on the
habitat-based component of PHABSIM
(lager et al. 1993). The CompMech
model of smallmouth bass is being
used to evaluate the effects of alterna-
tive flow regimes on nest success,
growth, mortality, and ultimately year
class strength in a Virginia stream to
identify instream flows that protect fish-
eries with minimum impact on hy-
dropower production.
A model of coexisting populations of
rainbow and brown trout in California
is being used to evaluate alternative in-
stream flow and temperature scenarios
(Van Winkle et al. 1996). Model predic-
tions will be compared with long-term
field observations before and after ex-
perimental flow increases; numerous
scientific papers are expected from this
intensive study.
An individual-based model of smolt
production by Chinook salmon, as part
of an environmental impact statement
for the Tuolumne River in California,
considered the minimum stream flows
necessary to ensure continuation and
maintenance of the anadromous fishery
(FERC 1996). That model, the Oak
Ridge Chinook salmon model (ORCM),
predicts annual production of salmon
smolts under specified reservoir mini-
mum releases by evaluating critical fac-
tors, including influences on upstream
migration of adults, spawning and incu-
bation of eggs, rearing of young, and
predation and mortality losses during
the downstream migration of smolts.
Other physical habitat analyses were
used to supplement the population
7-92
Chapter 7: Analysis of Corridor Condition
-------
model in evaluating benefits of alterna-
tive flow patterns. These habitat evalua-
tions are based on data from an
instream flow study; a stream tempera-
ture model was used to estimate flows
needed to maintain downstream tem-
peratures within acceptable limits for
salmon.
SALMOD
The conceptual and mathematical mod-
els for the Salmonid Population Model
(SALMOD) were developed for Chi-
nook salmon in concert with a 12-year
flow evaluation study in the Trinity
River of California using experts on the
local river system and fish species in
workshop settings (Williamson et al.
1993, Bartholow et al. 1993). SALMOD
was used to simulate young-of-year pro-
duction, assuming that the flow sched-
ules to be evaluated were released from
Lewiston Reservoir in every year from
1976 to 1992 (regardless of observed
reservoir inflow, storage, and release
limitations).
The structure of SALMOD is a middle
ground between a highly aggregated
classical population model that tracks
cohorts/size groups for a generally large
area without spatial resolution, and an
individual-based model that tracks indi-
viduals at a great level of detail for a
generally small area. The conceptual
model states that fish growth, move-
ment, and mortality are directly related
to physical hydraulic habitat and water
temperature, which in turn relate to the
timing and amount of regulated stream-
flow. Habitat capacity is characterized by
the hydraulic and thermal properties of
individual mesohabitats, which are the
model's spatial computational units.
Model processes include spawning
(with redd superimposition), growth
(including maturation), movement
(freshet-induced, habitat-induced, and
seasonal), and mortality (base, move-
ment-related, and temperature-related).
The model is limited to freshwater
habitat for the first 9 months of life; es-
tuarine and ocean habitats are not in-
cluded. Habitat area is computed from
flow/habitat area functions developed
empirically. Habitat capacity for each
life stage is a fixed maximum number
per unit of habitat available. Thus, a
maximum number of individuals for
each computational unit is calculated
for each time step based on streamflow
and habitat type. Rearing habitat capac-
ity is derived from empirical relations
between available habitat area and
number of individual fish observed.
Partly due to drought conditions, most
of the flow alternatives to be evaluated
did not actually occur during the flow
evaluation study. When there is insuffi-
cient opportunity to directly observe
and evaluate impacts of flow alterna-
tives on fish populations, SALMOD can
be used to simulate young-of-the-year
production that may result from pro-
posed flow schedules to be released or
regulated by a control structure such as
a reservoir or diversion.
Other physical habitat analyses can be
used to supplement population models
in evaluating benefits of alternative flow
patterns. In the Trinity River Flow
Study, a stream temperature model was
used to estimate flows needed to main-
tain downstream temperatures within
acceptable limits for salmon. Both the
ORCM (FERC 1996) and SALMOD
models concentrated on development,
growth, movement, and mortality of
young-of-year Chinook salmon but
with different mechanistic inputs, spa-
tial resolution, and temporal precision.
Biological Characteristics
7-93
-------
FAST
FORWARD
Preview
Chapter 8's
information on
vegetation-
hydroperiod
model.
Vegetation-Hydroperiod
Modeling
In most cases, the dominant factor that
makes the riparian zone distinct from
the surrounding uplands, and the most
important gradient in structuring varia-
tion within the riparian zone, is site
moisture conditions, or hydroperiod
(Figure 7.39). Hydroperiod is defined
as the depth, duration, and frequency
of inundation and is a powerful deter-
minant of what plants are likely to be
found in various positions in the ripar-
ian zone. Formalizing this relation as a
vegetation-hydroperiod model can pro-
vide a powerful tool for analyzing exist-
ing distributions of riparian vegetation,
casting forward or backward in time to
alternative distributions, and designing
new distributions. The suitability of site
conditions for various species of plants
can be described with the same concep-
tual approach used to model habitat
suitability for animals. The basic logic
of a vegetation-hydroperiod model is
straightforward. How wet a site is has a
lot to do with what plants typically
grow on the site. It is possible to mea-
sure how wet a site is and, more impor-
tantly, to predict how wet a site will be
based on the relation of the site to a
stream. From this, it is possible to esti-
mate what vegetation is likely to occur
on the site.
Components of a Vegetation-
hydroperiod Model
The two basic elements of the vegeta-
tion-hydroperiod relation are the physi-
cal conditions of site moisture at
various locations and the suitability of
those sites for various plant species. In
the simplest case of describing existing
patterns, site moisture and vegetation
can be directly measured at a number
of locations. However, to use the vege-
tation-hydroperiod model to predict or
design new situations, it is necessary to
predict new site moisture conditions.
The most useful vegetation-hydroperiod
models have the following three com-
ponents:
Characterization of the hydrology or pat-
tern of stream/low. This can take the
form of a specific sequence of flows,
a summary of how often different
flows occur, such as a flow duration
or flood frequency curve, or a repre-
sentative flow value, such as bankfull
discharge or mean annual discharge.
A relation between streamflow and mois-
ture conditions at sites in the riparian
zone. This relation can be measured
as the water surface elevation at a
variety of discharges and summarized
as a stage vs. discharge curve. It can
also be calculated by a number of
hydraulic models that relate water
surface elevations to discharge, taking
into account variables of channel
geometry and roughness or resistance
to flow. In some cases, differences in
simple elevation above the channel
bottom may serve as a reasonable
approximation of differences in
inundating discharge.
A relation between site moisture condi-
tions and the actual or potential vegeta-
tion distribution. This relation express-
es the suitability of a site for a plant
species or cover type based on the
moisture conditions at the site. It can
be determined by sampling the dis-
tribution of vegetation at a variety of
sites with known moisture condi-
tions and then deriving probability
distributions of the likelihood of
finding a plant on a site given the
moisture conditions at the site.
General relations are also available
from the literature for many species.
The nature and complexity of these
components can vary substantially and
still provide a useful model. However,
the components must all be expressed
7-94
Chapter 7: Analysis of Corridor Condition
-------
in consistent units and must have a do-
main of application that is appropriate
to the questions being asked of the
model (i.e., the model must be capable
of changing the things that need to be
changed to answer the question). In
many cases, it may be possible to for-
mulate a vegetation-hydroperiod model
using representations of stream hydrol-
ogy and hydraulics that have been de-
veloped for other analyses such as
channel stability, fish habitat suitability,
or sediment dynamics.
Identifying Non-equilibrium
Conditions
In altered or degraded stream systems,
current moisture conditions in the ri-
parian zone may be dramatically un-
suitable for the current, historical, or
desired riparian vegetation. Several con-
ditions can be relatively easily identi-
fied by comparing the distribution of
vegetation to the distribution of vegeta-
tion suitabilities.
The hydrology of the stream has
been altered; for example, if stream-
flow has diminished by diversion or
flood attenuation, sites in the ripari-
an zone may be drier and no longer
suitable for the historic vegetation or
for current long-lived vegetation that
was established under a previous
hydrologic regime.
The inundating discharges of plots in
the riparian zone have been altered
so that streamflow no longer has the
same relation to site moisture condi-
tions; for example, levees, channel
modifications, and bank treatments
may have either increased or
decreased the discharge required to
inundate plots in the riparian zone.
The vegetation of the riparian zone
has been directly altered, for exam-
ple, by clearing or planting so that
the vegetation on plots no longer
corresponds to the natural vegetation
for which the plots are suitable.
In many degraded stream systems all of
these things have happened. Under-
standing how the moisture conditions
of plots correspond to the vegetation in
the current system, as well as how they
will correspond in the restored system,
is an important element of formulating
reasonable restoration objectives and
designing a restoration plan.
Vegetation Effects of System
Alterations
In a vegetation-hydroperiod model,
vegetation suitability is determined by
streamflow and the inundating dis-
charges of plots in the riparian zone.
The model can be used to predict ef-
fects of alteration in streamflow or the
relations of streamflow to plot moisture
conditions on the suitability of the ri-
parian zone for different types of vege-
tation. Thus, the effects of flow
alterations and changes in channel or
bottomland topography proposed as
part of a stream restoration plan can be
examined in terms of changes in the
suitability of various locations in the ri-
parian zone for different plant species.
Figure 7.39:
Vegeta tion/water
relationship. Soil
moisture conditions
often determine the
plant communities
in riparian areas.
Source: C. Zabawa.
Biological Characteristics
7-95
-------
L
Flooding Toler
There is a large body of information on the flooding
tolerances of various plant species. Summaries of
this literature include Whitlow and Harris (1979) and
the mult/volume Impact of Water Level Changes on
Woody Riparian and Wetland Communities (Teskey
and Hinckley 1978, Walters et al. 1978, Lee and
Hinckley 1982, Chapman et al. 1982). This type of
information can be coupled to site moisture condi-
tions predicted by applying discharge estimates or
flood frequency analyses to the inundating dis-
charges of sites in the riparian zone. The resulting
relation can be used to describe the suitability of
sites for various plant species, e.g., relatively flood-
prone sites will likely have relatively flood-tolerant
plants. Inundating discharge is strongly related to
relative elevation within the floodplain. Other things
being equal (i.e., within a limited geographic area
and with roughly equivalent hydrologic regimes),
elevation relative to a representative water surface
line, such as bankfull discharge or the stage at mean
annual flow, can thus provide a reasonable surro-
gate for site moisture conditions. Locally determined
vegetation suitability can then be used to determine
the likely vegetation in various elevation zones.
Extreme Events and Disturbance
Requirements
Temporal variability is a particularly im-
portant characteristic of many stream
ecosystems. Regular seasonal differences
in biological requirements are examples
of temporal variability that are often
incorporated into biological analyses
based on habitat suitability and time
series simulations. The need for
episodic extreme events is easy to
Zonation of Vegetation
There are a number of statistical procedures for estimat-
ing the frequency and magnitude of extreme events
(see flood frequency analysis section of chapter 8) and
describing various aspects of hydrologic variation.
Changing these flow characteristics will likely change
some aspect of the distribution and abundance of organ-
isms. Analyzing more specific biological changes generally
requires defining the requirements of target species;
defining requirements of their food sources, competitors,
and predators; and considering how those requirements
are influenced by episodic disturbance events.
ignore because these are so widely per-
ceived as destructive both of biota and
of constructed river features. In reality,
however, these extreme events seem to
be essential to physical channel mainte-
nance and to the long-term suitability
of the riverine ecosystem for distur-
bance-dependent species. Cottonwood
in western riparian systems is one well-
understood case of a disturbance-de-
pendent species. Cottonwood
regeneration from seed is generally re-
stricted to bare, moist sites. Creating
these sites depends heavily on channel
movement (meandering, narrowing,
avulsion) or new flood deposits at high
elevations. In some western riparian
systems, channel movement and depo-
sition tend to occur infrequently in as-
sociation with floods. The same events
are also responsible for destroying
stands of trees. Thus maintaining good
conditions for existing stands, or fixing
the location of a stream's banks with
structural measures, tends to reduce the
regeneration potential and the long-
term importance of this disturbance-
dependent species in the system as a
whole.
7-96
Chapter 7: Analysis of Corridor Condition
-------
Restoration
Design
-------
8.A Valley Form, Connectivity, and Dimension
How do you incorporate all the spatial dimensions of the landscape into stream corridor
restoration design?
« What criteria can be applied to facilitate good design decisions for stream
corridor restoration?
8.B Soil Properties
How do soil properties impact the design of restoration activities?
What are the major functions of soils in the stream corridor?
How are important soil characteristics, such as soil microfauna and soil salinity, accounted for
in the design process?
8.C Vegetative Communities
What is the role of vegetative communities in stream corridor restoration?
What functions do vegetative communities fulfill in a stream corridor?
What are some considerations in designing plant community restoration to ensure that all
landscape functions are addressed?
What is soil bioengineering and what is its role in stream corridor restoration?
8.D Riparian / Terrestrial Habitat Recovery
What are some specific tools and techniques that can be used to ensure recovery of riparian
and terrestrial habitat recovery?
8.E Stream Channel Restoration
When is stream channel reconstruction an appropriate restoration option?
How do you delineate the stream reach to be reconstructed?
How is a stream channel designed and reconstructed?
What are important factors to consider in the design of channel reconstruction
(e.g., alignment and average slope, channel dimensions)?
Are there computer models that can assist with the design of channel reconstruction?
8.F Streambank Restoration Design
When should Streambank stabilization be included in a restoration?
How do you determine the performance criteria for Streambank treatment, including the
methods and materials to be used?
What are some Streambank stabilization techniques that can be considered for use?
8.G In-Stream Habitat Recovery
What are the principal factors controlling the quality of instream habitat?
How do you determine if an instream habitat structure is needed, and what type of structure
is most appropriate?
What procedures can be used to restore instream habitat?
What are some examples of instream habitat structures?
What are some important questions to address before designing, selecting or installing an
instream habitat structure?
8.H Land Use Scenarios
What role does land use play in stream corridor degradation and restoration?
What design approaches can be used to address the impacts of various land use?(e.g., dams,
agriculture, forestry, grazing, mining, recreation, urbanization)?
What are some disturbances that are often associated with specific land uses?
What restoration measures can be used to mitigate the impacts of various land uses?
What are the potential effects of the restoration measures?
-------
Restoration
Design
8.A Valley Form, Connectivity, and
Dimension
8.B Soil Properties
8.C Plant Communities
Habitat Measures
Stream Channel Restoration
Streambank Restoration
8.D
8.E
8.F
8.G Instream Habitat Recovery
8.H Land Use Scenarios
Design can be defined as the inten-
tional shaping of matter, energy, and
process to meet an expressed need. Plan-
ning and design connect natural processes
and cultural needs through exchanges of
materials, flows of energy, and choices
of land use and management. One test
of a successful stream corridor design is
how well the restored system sustains
itself over time while accommodating
identified needs.
To achieve success, those carrying out
restoration design and implementation
in variable-land-use settings must under-
stand the stream corridor, watershed,
and landscape as a complex of
working ecosystems that
influence and are influenced
by neighboring ecosystems
(Figure 8.1). The probability
of achieving long-term, self-
sustaining functions across this
spatial complex increases with
Figure 8.1: Stream running through a
wet meadow. Restoration design must
consider site-specific conditions as an
integral part of larger systems.
-------
"Leave It Alone / Let It Heal Itself"
There is a renewed emphasis on recovering damaged rivers (Barinaga
1996). Along with this concern, however, people should be reminded
periodically that they serve as stewards of watersheds, not just tinkerers
with stream sites. Streams in pristine condition, for example, should not
be artificially "improved" by active rehabilitation methods.
At the other end of the spectrum, and particularly where degradation is
caused by off-stream activities, the best solution to a river management
problem might be to remove the problem source and "let it heal itself."
Unfortunately, in severely degraded streams this process can take a long
time. Therefore the "leave it alone" concept can be the most difficult
approach for people to accept (Gordon et al. 1992).
an understanding of these relation-
ships, a common language for ex-
pressing them, and subsequent
response. Designing to achieve
stream- or corridor-specific solu-
tions might not resolve problems
or recognize opportunities in the
landscape.
Stream corridor restoration design
is still largely in an experimental
stage. It is known however, that
restoration design must consider
site-specific or local conditions to
be successful. That is, the design
criteria, standards, and specifica-
tions should be for the specific pro-
ject in a specific physical, climatic,
and geographic location. These ini-
tiatives, however, can and should
work with, rather than against, the
larger systems of which they are an
integral part.
This approach produces multiple
benefits, including:
m A healthy, sustainable pattern of
land uses across the landscape.
Improved natural resource quality
and quantity.
m Restored and protected stream
corridors and associated ecosys-
tems.
m A diversity of native plants and
animals.
m A gene pool that promotes har-
diness, disease resistance, and
adaptability.
m A sense of stewardship for pri-
vate landowners and the public.
m Improved management measures
that avoid narrowly focused and
fragmented land treatment.
8-2
Chapter 8: Restoration Design
-------
Building on information presented
in Parts I and II, this chapter con-
tains design guidance and tech-
niques to address changes caused
by major disturbances and to re-
store stream corridor structure and
function to a desired level. It begins
with larger-scale influences that
design may have on stream corridor
ecosystems, offers design guidance
primarily at the stream corridor and
stream scales, and concludes with
land use scenarios.
The chapter is divided into seven
sections.
Section 8.A: Valley Form,
Connectivity, and Dimension
This section focuses on restoring
structural characteristics that prevail
at the stream corridor and land-
scape scales.
Section 8.B: Soil Properties
The restoration of soil properties
that are critical to stream corridor
structure and functions are ad-
dressed in this section.
Section 8.C: Plant Communities
Restoring vegetative communities
is a highly visible and integral
component of a functioning
stream corridor.
Section 8.D: Habitat Measures
This section presents design guid-
ance for some habitat measures.
They are often integral parts of
stream corridor structure and
functions.
Section 8.E: Stream Channel
Restoration
Restoring stream channel structure
and functions is often a fundamen-
tal step in restoring stream corridors.
Section 8.F: Stream bank
Restoration
This section focuses on design
guidelines and related techniques
for streambank stabilization. These
measures can help reduce surface
runoff and sediment transport to
the stream.
Section 8.G: Instream Habitat
Recovery
Restoring instream habitat structure
and functions is often a key com-
ponent of stream corridor restora-
tion.
Section 8.H: Land Use Scenarios
This final section offers broad
design concepts in the context
of major land use scenarios.
Restoration Design
8-3
-------
8.A Valley Form, Connectivity, and Dimension
Valley form, connectivity, and dimen-
sion are variable structural characteris-
tics that determine the interrelationship
of functions at multiple scales. Valley
intersections (nodes) with tributary
stream corridors, slope of valley sides,
and floodplain gradient are characteris-
tics of valley form that influence many
functions (Figure 8.2).
Figure 8.2: Stream corridors, (a) Stream valley
side slopes and (b) floodplain gradients
influence stream corridor function.
The broad concept of connectivity, as
opposed to fragmentation, involves
linkages of habitats, species, communi-
ties, and ecological processes across
multiple scales (Noss 1991). Dimension
encompasses width, linearity, and edge
effect, which are critical for movement
of species, materials, and energy within
the stream corridor and to or from
ecosystems in the surrounding land-
scape. Design should therefore address
these large-scale characteristics and their
effect on functions.
Valley Form
In some cases, entire stream valleys
have changed to the point of obscuring
geomorphic boundaries, making stream
corridor restoration difficult. Volcanoes,
earthquakes, and landslides are exam-
ples of natural disturbances that cause
changes in valley form. Encroachment
and filling of floodplains are among the
human-induced disturbances that mod-
ify valley shape.
Stream Corridor Connectivity
and Dimension
Connectivity and dimensions of the
stream corridor present a set of design-
related decisions to be made. How
wide should the corridor be? How long
should the corridor be? What if there
are gaps in the corridor? These struc-
tural characteristics have a significant
impact on corridor functions. The
width, length, and connectivity of exist-
ing or potential stream corridor vegeta-
tion, for example, are critical to habitat
functions within the corridor and adja-
cent ecosystems.
Generally, the widest and most contigu-
ous stream corridor which achieves
habitat, conduit, filter, and other func-
tions (see Chapter 2) should be an
Chapter 8: Restoration Design
-------
ecologically derived goal of restoration.
Thresholds for each function are likely
found at different corridor widths. The
appropriate width varies according to
soil type, with steep slopes requiring a
wider corridor for filter functions. A
conservative indicator of effective corri-
dor width is whether a stream corridor
can significantly prevent chemical con-
taminants contained in runoff from
reaching the stream (Forman 1995).
As discussed in Chapter 1, the corridor
should extend across the stream, its
banks, the floodplain, and the valley
slopes. It should also include a portion
of upland for the entire stream length
to maintain functional integrity (For-
man and Godron 1986).
A contiguous, wide stream corridor
might not be achievable, however, par-
ticularly where competing land uses
prevail. In these cases, a ladder pattern
of natural habitat crossing the flood-
plain and connecting the upland seg-
ments might facilitate sediment
trapping during floods and provide
hydraulic storage and organic matter
for the stream system (Dramstad et al.
1996).
Figure 8.3 presents an example of these
connections. The open areas within the
ladder pattern are representative of
areas that are unavailable for restora-
tion because of competing land uses.
Innovative management practices that
serve the functions of the corridor be-
yond land ownership boundaries can
often be prescribed where land owners
are supportive of restoration. Altering
land cover, reducing chemical inputs,
carefully timed mowing, and other
management practices can reduce dis-
turbance in the corridor.
Practical considerations may restrict
restoration to a zone of predefined
width adjacent to the stream. Although
often unavoidable, such restrictions
transitional
upland fringe
Figure 8.3: Connections across a stream corridor. A ladder pattern of
natural habitat can restore structure and functions where competing
land uses prevail.
Adapted from Ecology of Greenways: Design and Function of Linear
Conservation Areas. Edited by Smith and Hellmund. © University of
Minnesota Press 1993.
tend to result in underrepresentation of
older, off-channel environments that
support vegetation different from that
in stream-front communities. Restrict-
ing restoration to a narrow part of the
stream corridor usually does not restore
the full horizontal diversity of broad
floodplains, nor does it fully accommo-
date functions that occur during flood
events, such as use of the floodplain by
aquatic species (Wharton et al. 1982).
In floodplains where extensive subsur-
face hydrologic connections exist, limit-
ing restoration to streamside buffer
zones is not recommended since signifi-
cant amounts of energy, nutrient trans-
formation, and invertebrate activities
can occur at great distances from the
stream channel outside the buffer areas
(Sedell et al. 1990). Similarly, failure to
anticipate channel migration or peri-
odic beaver activity might result in a
corridor that does not accommodate
Valley Form, Connectivity, and Dimension
8-5
-------
Corridor Width Variables
The minimum width of stream corridors based on ecological criteria (Figure 8.4).
Five basic situations in a river system are identified, progressing from seepage to river.
The key variables determining minimum corridor width are listed under each.
Figure 8.4: Factors for determining minimum corridor widths. Stream corridor functions are
directly influenced by corridor width.
Source: Forman 1-995. Reprinted with permission of Cambridge University Press.
Seepage
1. Sponge effect for hydrologic flows, mimimizing
downstream flooding
2. Control of dissolved-substance inputs from matrix
1st Order Stream
1. Same as for seepage
2nd to 4th Order Stream with Closed Canopy
1. Conduit for upland interior species; both sides of
stream so species readily crossing floodplain have
alternate routes
Control of dissolved-substance inputs from matrix
Conduit for streambank and floodplain species,
where beaver activities maintain water across the
floodplain and alter hillslope vegetation
4. Minimize hillslope erosion
5. Sponge effect for hydrologic flows, minimizing
downstream flooding
6. Friction effect, minimizing downstream sedimentation
7. Protect high habitat diversity and species
richness of floodplain
2nd to 4th Order Stream with Open Canopy
1. Same as for 2nd to ca. 4th order stream, closed canopy
2. Provide interior habitat for species conduit, as
migrating open stream intersects hillslopes
causing them to be open habitat
5th to 10th Order River
1. Conduit for upland interior species, on both sides
of river so species that rarely can cross the
floodplain have a route on each side
2. Provide interior habitat for species conduit, as
migrating open river intersects hillslopes
causing them to be open habitat
3. Minimize hillslope erosion
4. Shade and logs provide fish habitat where
river is adjacent to hillslope
5. Source of soil organic matter, an important base
of the river food chain
6. Shade and logs provide fish habitat wherever
river is as it migrates across the floodplain
7. Genetic benefit to upland species that can use
habitat continuity to infrequently cross floodplain
8. Sponge effect for hydrologic flows, minimizing
downstream flooding
9. Friction effect minimizing downstream sedimentation
10.Protect high habitat diversity and species
richness of floodplain
11.Conduit for semiaquatic and other organisms
dependent on river channel resources
matrix
edge portion of corridor in upland
interior portion of corridor in upland
hillslope
floodplain
meander band
interior of patch of natural floodplain vegetation
edge of patch of natural floodplain vegetation
other ecologically-compatible land use
8-6
Chapter 8: Restoration Design
-------
fundamental dynamic processes
(Malanson 1993).
As previously discussed, restoration of
an ecologically effective stream corridor
requires consideration of uplands adja-
cent to the channel and floodplain.
Hillslopes might be a source area for
water maintaining floodplain wetlands,
a sediment source for channels on
bedrock, and the principal source of or-
ganic debris in high-gradient streams.
Despite these considerations, stream
corridors are often wrongly viewed as
consisting of only the channel and an
adjacent vegetative buffer. The width
of the buffer is determined by specific
objectives such as control of agricultural
runoff or habitat requirements of par-
ticular animal species. This narrow
definition obviously does not fully
accommodate the extent of the func-
tions of a stream corridor; but where
the corridor is limited by immovable
resource uses, it often becomes a part
of a restoration strategy.
Cognitive Approach: The
Reference Stream Corridor
Ideal stream corridor widths, as previ-
ously defined, are not always achievable
in the restoration design. A local refer-
ence stream corridor might provide di-
mensions for designing the restoration.
Examination of landscape patterns is
beneficial in identifying a reference
stream corridor. The reference should
provide information about gap width,
landform, species requirements, vegeta-
tive structure, and boundary characteris-
tics of the stream corridor (Figure 8.5).
Restoration objectives determine the de-
sired levels of functions specified by the
restoration design. If a nearby stream
corridor in a similar landscape setting
and with similar land use variables pro-
vides these functions adequately, it can
be used to indicate the connectivity and
Figure 8.5: A maple in a New Mexico floodplain.
A rare occurrence of a remnant population may
reflect desired conditions in a reference stream
corridor.
width attributes that should be part of
the design.
Analytical Approach: Functional
Requirements of a Target Species
The restoration plan objectives can be
used to determine dimensions for the
stream corridor restoration. If, for ex-
ample, a particular species requires that
the corridor offer interior habitat, the
corridor width is sized to provide the
necessary habitat. The requirements of
the most sensitive species typically are
used for optimum corridor dimensions.
When these dimensions extend beyond
the land base available for restoration,
management of adjacent land uses be-
comes a tool for making the corridor
effectively wider than the project para-
meters.
Optimum corridor dimensions can be
achieved through collaboration with in-
dividuals and organizations who have
management authority over adjacent
lands. Dimensions include width of
Valley Form, Connectivity, and Dimension
8-7
-------
edge effect associated with boundaries
of the corridor and pattern variations
within the corridor, maximum accept-
able width of gaps within the corridor,
and maximum number of gaps per unit
length of corridor.
Designing for Drainage and
Topography
The stream corridor is dependent on in-
teractions with the stream to sustain its
character and functions (see Chapter 2).
Therefore, to the extent feasible, the
restoration process should include
blockage of artificial drainage systems,
removal or setback of artificial levees,
and restoration of natural patterns of
floodplain topography, unless these ac-
tions conflict with other social or envi-
ronmental objectives (e.g., flooding or
habitat).
Restoration of microrelief is particularly
important where natural flooding has
been reduced or curtailed because a
topographically complex floodplain
supports a mosaic of plant communi-
ties and ecosystem functions as a result
of differential ponding of rainfall and
interception of ground water. Microre-
lief restoration can be accomplished by
selective excavation of historic features
within the floodplain such as natural
wetlands, levees, oxbows, and aban-
doned channels. Aerial photography
and remotely sensed data, as well as ob-
servations in reference corridors, pro-
vide an indication of the distribution
and dimensions of typical floodplain
microrelief features.
8.B Soil Properties
Stream corridor functions depend not
only on the connectivity and dimen-
sions of the stream corridor, but also
on its soils and associated vegetation.
The variable nature of soils across and
along stream corridors results in diverse
plant communities (Figure 8.6). When
designing stream corridor restoration
measures, it is important to carefully
analyze the soils and their related
potentials and limitations to support
diverse native plant and animal com-
munities, as well as for restoration
involving channel reconstruction.
Where native floodplain soils remain
in place, county soil surveys should be
used to determine basic site conditions
and fertility and to verify that the pro-
posed plant species to be restored are
appropriate. Most sites with fine-
textured alluvium will not require sup-
plemental fertilization, or fertilizers
might be required only for initial estab-
lishment. In these cases excessive fertil-
Figure 8.6: Distinct vegetation zones along
a mountain stream. Variable soils result in
diverse plant communities.
8-8
Chapter 8: Restoration Design
-------
ization could encourage competing
weed species or exotics. Soil should al-
ways be tested before making any fertil-
izer design recommendations.
County soil surveys can provide basic
information such as engineering limita-
tions or suitabilities. Site-specific soil
samples should, however, be collected
and tested when the restoration in-
volves alternatives that include stream
reconstruction.
The connections and feedback loops
between runoff and the structure and
functions of streams are described in
Chapter 2. The functions of soil and
the connection between soil quality,
runoff, and water quality are also
established in that chapter. These
connections need to be identified and
considered in any stream corridor
restoration plan and design. For all
land uses, emphasis needs to be placed
on implementing conservation land
treatment that promotes soil quality
and the ability of the soils to carry out
four major functions:
Regulating and partitioning the
flow of water (a conduit and filter
function).
Storing and cycling nutrients and
other chemicals (a sink and filter
function).
Filtering, buffering, degrading,
immobilizing, and detoxifying
organic and inorganic materials
(a filter, sink, and barrier function).
Supporting biological activity in
the landscape (a source and habitat
function).
References such as Field Office Technical
Guide (USDA-NRCS) contain guidance
on the planning and selection of con-
servation practices and are available at
most county offices.
Figure 8.7: Compaction of streamside soil.
Compact soils may require deep plowing,
ripping, or vegetative practices to break up the
impermeable layer.
Compaction
Soils that have been in row crops or
have undergone heavy equipment traffic
(such as that associated with construc-
tion) can develop a relatively imperme-
able compacted layer (plow pan or hard
pan) that restricts water movement and
root penetration (Figure 8.7). Such
soils might require deep plowing, rip-
ping, or vegetative practices to break up
the pan, although even these are some-
times ineffective. Deep plowing is usu-
ally expensive and, at least in the East,
should be used only if the planting of a
species that is able to penetrate the pan
layer is not a viable option.
Soil Microfauna
On new or disturbed substrates, or on
row-cropped sites, essential soil mi-
croorganisms (particularly mycorrhizal
fungi) might not exist. These are most
effectively replaced by using rooted
plant material that is inoculated or nat-
urally infected with appropriate fungi.
Stockpiling and reincorporating local
Soil Properties
8-9
-------
topsoils into the substrate prior to
planting is also effective (Allen 1995).
Particular care should be taken to avoid
disturbing large trees or stumps since
the soils around and under them are
likely source areas for reestablishment
of a wide variety of microorganisms. In-
oculation can be useful in restoring
some soil mycorrhizal fungi for particu-
lar species when naturally infected
plant stock is unavailable.
Soil Salinity
Soil salinity is another important con-
sideration in restoration because salt
accumulation in the soil can restrict
plant growth and the establishment of
riparian species. High soil salinity is
not common in healthy riparian eco-
systems where annual spring floods
remove excess salts. Soil salinity can
also be altered by leaching salts through
the soil profile with irrigation (Ander-
son et al. 1984). Because of agricultural
drainage and altered flows due to dam
construction, salt accumulation often
contributes to riparian plant commu-
nity declines.
Soil sampling throughout a restoration
site may be necessary since salinity can
vary across a floodplain, even on sites of
less than 20 acres. If salinity is a prob-
lem, one must select plant materials
adapted to a saline soil environment.
8.C Plant Communities
Vegetation is a fundamental controlling
factor in stream corridor function.
Habitat, conduit, filter/barrier, source,
and sink functions are all critically tied
to the vegetative biomass amount, qual-
ity, and condition (Figure 8.8). Restora-
tion designs should protect existing
native vegetation and restore vegetative
structure to result in a contiguous and
connected stream corridor.
Restoration goals can be general (e.g.,
returning an area to a reference condi-
tion) or specific (e.g., restoring habitats
for particular species of interest such as
the least Bell's vireo, Vireo bellii [Baird
and Rieger 1988], or yellow-billed
cuckoo, Coccyzus americana [Anderson
and Laymon 1988]).
Numerous shrubs and trees have been
evaluated as restoration candidates, in-
cluding willows (Svejcar et al. 1992,
Hoag 1992, Conroy and Svejcar 1991,
Anderson et al. 1978); alder, service-
berry, oceanspray, and vine maple
(Flessner et al. 1992); cottonwood and
poplar (Hoag 1992); Sitka and thinleaf
alder (Java and Everett 1992); palo
verde and honey mesquite (Anderson
et al. 1978); and many others. Selec-
tion of vegetative species may be based
on the desire to provide habitat for a
particular species of interest. The cur-
rent trend in restoration, however, is
to apply a multispecies or ecosystem
approach.
Figure 8.8: Stream corridor vegetation.
Vegetation is a fundamental controlling
factor in the functioning of stream corridors.
8-10
Chapter 8: Restoration Design
-------
Riparian Buffer Strips
Managers of riparian systems have long
recognized the importance of buffer
strips, for the following reasons
(USAGE 1991):
Provide shade that reduces water
temperature.
Cause deposition of (i.e., filter)
sediments and other contaminants.
Reduce nutrient loads of streams.
Stabilize streambanks with vegeta-
tion.
Reduce erosion caused by uncon-
trolled runoff.
Provide riparian wildlife habitat.
Protect fish habitat.
Maintain aquatic food webs.
Provide a visually appealing green-
belt.
Provide recreational opportunities.
Although the value of buffer strips is
well recognized, criteria for their sizing
are variable. In urban stream corridors a
wide forest buffer is an essential com-
ponent of any protection strategy. Its
primary value is to provide physical
protection for the stream channel from
future disturbance or encroachment. A
network of buffers acts as the right-of-
way for a stream and functions as an in-
tegral part of the stream ecosystem.
Often economic and legal considera-
tions have taken precedence over eco-
logical factors. For Vermont, USAGE
(1991) suggests that narrow strips
(100 ft. wide) may be adequate to
provide many of the functions listed
above. For breeding bird populations
on Iowa streams, Stauffer and Best
(1980) found that minimum strip
widths varied from 40 ft. for cardinals
to 700 ft. for scarlet tanagers, American
redstarts, and rufous-sided towhees.
In urban settings buffer sizing criteria
may be based on existing site controls
as well as economic, legal, and ecologi-
cal factors. Practical performance crite-
ria for sizing and managing urban
buffers are presented in the box Design-
ing Urban Stream Buffers. Clearly, no
single recommendation would be suit-
able for all cases.
Because floodplain/riparian habitats are
often small in area when compared to
surrounding uplands, meeting the mini-
mum area needs of a species, guild, or
community is especially important.
Minimum area is the amount of habitat
required to support the expected or ap-
propriate use and can vary greatly
across species and seasons. For example,
Skagen (USGS, Biological Resources Di-
vision, Ft. Collins, Colorado; unpubl.
data) found that, contrary to what
might be considered conventional wis-
dom, extensive stream corridors in
southeastern Arizona were not more
important to migrating birds than iso-
lated patches or oases of habitat. In
fact, oases that were <2.5 miles long
and <30 ft. in width had more species
and higher numbers of nonbreeding
migrants than did corridors. Skagen
found that the use of oases, as well as
corridors, is consistent with the ob-
served patterns of long distance mi-
grants, where migration occurs along
broad fronts rather than north-south
corridors. Because small and/or isolated
patches of habitat can be so important
to migrants, riparian restoration efforts
should not overlook the important op-
portunities they afford.
Existing Vegetation
Existing native vegetation should be re-
tained to the extent feasible, as should
woody debris and stumps (Figure 8.9).
In addition to providing habitat and
erosion and sediment control, these fea-
tures provide seed sources and harbor a
Plant Communities
8-11
-------
Designing Urban Stream Buffers
The ability of an urban stream buffer to realize its
many benefits depends to a large degree on how
well it is planned, designed, and maintained. Ten
practical performance criteria are offered to gov-
ern how a buffer is to be sized, managed, and
crossed. The key criteria include:
Criteria 1: Minimum total buffer width.
Most local buffer criteria require that development
be set back a fixed and uniform distance from the
stream channel. Nationally, urban stream buffers
range from 20 to 200 ft. in width from each side
of the stream according to a survey of 36 local
buffer programs, with a median of 100 ft.
(Schueler 1995). In general, a minimum base
width of at least 100 feet is recommended to pro-
vide adequate stream protection.
Criteria 2: Three-zone buffer system.
Effective urban stream buffers have three lateral
zonesstream side, middle core, and outer zone.
Each zone performs a different function, and has a
different width, vegetative target and manage-
ment scheme. The stream side zone protects the
physical and ecological integrity of the stream
ecosystem. The vegetative target is mature riparian
forest that can provide shade, leaf litter, woody
debris, and erosion protection to the stream. The
middle zone extends from the outward boundary
of the stream side zone, and varies in width,
depending on stream order, the extent of the 100-
yr floodplain, adjacent steep slopes, and protected
wetland areas. Its key functions are to provide fur-
ther distance between upland development and
the stream. The vegetative target for this zone is
also mature forest, but some clearing may be
allowed for storm water management, access, and
recreational uses.
The outer zone is the buffer's "buffer," an addi-
tional 25-ft. setback from the outward edge of the
middle zone to the nearest permanent structure.
In most instances, it is a residential backyard. The
vegetative target for the outer zone is usually turf
or lawn, although the property owner is encour-
aged to plant trees and shrubs, and thus increase
the total width of the buffer. Very few uses are
restricted in this zone. Indeed, gardening, compost
piles, yard wastes, and other common residential
activities often will occur in the outer zone.
Criteria 3: Predevelopment vegetative target.
The ultimate vegetative target for urban stream
buffers should be specified as the predevelopment
riparian plant communityusually mature forest.
Notable exceptions include prairie streams of the
Midwest, or arroyos of the arid West, that may
have a grass or shrub cover in the riparian zone. In
general, the vegetative target should be based on
the natural vegetative community present in the
floodplain, as determined from reference riparian
zones. Turf grass is allowed for the outer zone of
the buffer.
Criteria 4: Buffer expansion and contraction.
Many communities require that the minimum
width of the buffer be expanded under certain
conditions. Specifically, the average width of the
middle zone can be expanded to include:
the full extent of the 100-yr floodplain;
all undevelopable steep slopes (greater than
sfeep slopes (5 to 25% slope, at four additional
ft. of slope per one percent increment of slope
above 5%); or
any adjacent delineated wetlands or critical
habitats.
Criteria 5: Buffer delineation.
Three key decisions must be made when delineat-
ing the boundaries of a buffer. At what mapping
scale will streams be defined? Where does the
stream begin and the buffer end? And from what
8-12
Chapter 8: Restoration Design
-------
point should the inner edge of the buffer be mea-
sured? Clear and workable delineation criteria
should be developed.
Criteria 6: Buffer crossings.
Major objectives for stream buffers are to main-
tain an unbroken corridor of riparian forest and to
allow for upstream and downstream fish passage
in the stream network. From a practical stand-
point, however, it is not always possible to try to
meet these goals everywhere along the stream
buffer network. Some provision must be made for
linear forms of development that must cross the
stream or the buffer, such as roads, bridges, fair-
ways, underground utilities, enclosed storm drains
or outfall channels.
Criteria 7: Storm water runoff.
Buffers can be an important component of the
storm water treatment system at a development
site. They cannot, however, treat all the storm
water runoff generated within a watershed (gen-
erally, a buffer system can only treat runoff from
less than 10% of the contributing watershed to
the stream). Therefore, some kind of structural
BMP must be installed to treat the quantity and
quality of storm water runoff from the remaining
90% of the watershed.
Criteria 8: Buffers during plan review and
construction.
The limits and uses of the stream buffer systems
should be well defined during each stage of the
development processfrom initial plan review,
through construction.
Criteria 9: Buffer education and enforcement.
The future integrity of a buffer system requires a
strong education and enforcement program. Thus,
it is important to make the buffer "visible" to the
community, and to encourage greater buffer
awareness and stewardship among adjacent resi-
dents. Several simple steps can be taken to accom-
plish this.
Mark the buffer boundaries with permanent
signs that describe allowable uses
Educate buffer owners about the benefits and
uses of the buffer with pamphlets, stream walks,
and meetings with homeowners associations
Ensure that new owners are fully informed
about buffer limits/uses when property is
sold or transferred
Engage residents in a buffer stewardship
program that includes reforestation and
backyard "bufferscaping" programs
Conduct annual buffer walks to check
on encroachment
Criteria 10: Buffer flexibility.
In most regions of the country, a hundred-foot
buffer will take about 5% of the total land area
in any given watershed out of use or production.
While this constitutes a relatively modest land
reserve at the watershed scale, it can be a signifi-
cant hardship for a landowner whose property is
adjacent to a stream. Many communities are legiti-
mately concerned that stream buffer requirements
could represent an uncompensated "taking" of
private property. These concerns can be eliminated
if a community incorporates several simple mea-
sures to ensure fairness and flexibility when
administering its buffer program. As a general
rule, the intent of the buffer program is to modify
the location of development in relation to the
stream but not its overall intensity. Some flexible
measures in the buffer ordinance include:
Maintaining buffers in private ownership
Buffer averaging
Density compensation
Variances
Conservation easements
Plant Communities
8-13
-------
Figure 8.9: Remnant vegetation and woody
debris along a stream. Attempts should be
made to preserve existing vegetation within
the stream corridor.
variety of microorganisms, as described
above. Old fencerows, vegetated stumps
and rock piles in fields, and isolated
shade trees in pastures should be re-
tained through restoration design, as
long as the dominant plant species are
native or are unlikely to be competitors
in a matrix of native vegetation (e.g.,
fruit trees).
Nonnative vegetation can prevent estab-
lishment of desirable native species or
become an unwanted permanent com-
ponent of stream corridor vegetation.
For example, kudzu will kill vegetation.
Generally, forest species planted on
agricultural land will eventually shade
out pasture grasses and weeds, although
some initial control (disking, mowing,
burning) might be required to ensure
tree establishment.
Plant Community Restoration
An objective of stream corridor restora-
tion work might be to restore natural
patterns of plant community distribu-
tion within the stream corridor. Numer-
ous publications describe general
distribution patterns for various geo-
morphic settings and flow conditions
(e.g., Brinson et al. 1981, Wharton et al.
1982), and county soil surveys generally
describe native vegetation for particular
soils. More detailed and site-specific
plant community descriptions may be
available from state Natural Heritage
programs, chapters of The Nature Con-
servancy, or other natural resources
agencies and organizations.
Examination of the reference stream
corridor, however, is often the best way
to develop information on plant com-
munity composition and distribution.
Once reference plant communities are
defined, design can begin to detail the
measures required to restore those
communities (Figure 8.10). Rarely is
it feasible or desirable to attempt to
plant the full complement of appropri-
ate species on a particular site. Rather,
the more typical approach is to plant
the dominant species or those species
unlikely to colonize the site readily.
For example, in the complex bottom-
I
Figure 8.10: A thriving and diverse plant com-
munity within a stream corridor. Examination
of reference plant communities is often the
best way to develop information on the com-
position and distribution of plant communities
at the restoration site.
8-14
Chapter 8: Restoration Design
-------
land hardwood forests of the Southeast,
the usual focus is on planting oaks.
Oaks are heavy-seeded, are often shade-
intolerant, and may not be able to read-
ily invade large areas for generations
unless they are introduced in the initial
planting plan, particularly if flooding
has been reduced or curtailed. It is as-
sumed that lighter-seeded and shade-
tolerant species will invade the site at
rates sufficient to ensure that the result-
ing forest is adequately diverse. This
process can be accelerated by planting
corridors of fast-growing species (e.g.,
cottonwoods) across the restoration
area to promote seed dispersal.
In areas typically dominated by cotton-
woods and willows, the emphasis might
be to emulate natural patterns of colo-
nization by planting groves of particular
species rather than mixed stands, and by
staggering the planting program over a
period of years to ensure structural vari-
ation. Where conifers tend to eventually
succeed riparian hardwoods, some
restoration designs may include scat-
tered conifer plantings among blocks of
pioneer species, to accelerate the transi-
tion to a conifer-dominated system.
Large-scale restoration work sometimes
includes planting of understory species,
particularly if they are required to meet
specific objectives such as providing es-
sential components of endangered spe-
cies habitat. However, it is often difficult
to establish understory species, which
are typically not tolerant to full sun, if
the restoration area is open. Where par-
ticular understory species are unlikely
to establish themselves for many years,
they can be introduced in adjacent
forested sites, or planted after the initial
tree plantings have matured sufficiently
to create appropriate understory condi-
tions. This may also be an appropriate
approach for introducing certain over-
story species that might not survive
planting in full sun (Figure 8.11).
Figure 8.11: Restoration of understory plant
species. Understory species can be introduced
at the restoration site after the initial tree
plantings have matured sufficiently.
The concept of focusing restoration ac-
tions on a limited group of overstory
species to the exclusion of understory
and other overstory species has been
criticized. The rationale for favoring
species such as oaks has been to ensure
that restored riparian and floodplain
areas do not become dominated by op-
portunistic species, and that wildlife
functions and timber values associated
with certain species will be present as
soon as possible. It has been docu-
mented that heavy-seeded species such
as oaks may be slow to invade a site
unless planted (see Tennessee Valley
Authority Floodplain Reforestation
Projects50 Years Later), but differen-
tial colonization rates probably exclude
a variety of other species as well. Cer-
tainly, it would be desirable to intro-
duce as wide a variety of appropriate
species as possible; however, costs and
the difficulties of doing supplemental
plantings over a period of years might
preclude this approach in most
instances.
Plant Communities
8-15
-------
Low Water Availability
In areas where water levels are low, artificial plantings will not survive if their
roots cannot reach the zone of saturation. Low water availability was associ-
ated with low survival rates in more than 80 percent of unsuccessful revege-
tation work examined in Arizona (Briggs 1992). Planting long poles (20 ft.)
of Fremont cottonwood (Populus fremontii) and Gooding willow in augered
holes has been successful where the ground water is more than 10 ft. below
the surface (Swenson and Mullins 1985). In combination with an irrigation
system, many planted trees are able to reach ground water 10 ft. below the
surface when irrigated for two seasons after planting (Carothers et al. 1990).
Sites closest to ground water, such as secondary channels, depressions, and
low sites where water collects, are the best candidates for planting, although
low-elevation sites are more prone to flooding and flood damage to the
plantings. Additionally, the roots of many riparian species may become
dormant or begin to die if inundated for extended periods of time (Burrows
andCarr 1969).
Plant species should be distributed
within a restoration site with close at-
tention to microsite conditions. In addi-
tion, if stream meandering behavior or
scouring flows have been curtailed, spe-
cial effort is required to maintain com-
munities that normally depend on such
behavior for natural establishment.
These may include oxbow and swale
communities (bald cypress, shrub wet-
lands, emergent wetlands), as well as
communities characteristic of newly de-
posited soils (cottonwoods, willows,
alders, silver maple, etc.). It is important
to recognize that planting vegetation on
sites where regeneration mechanisms no
longer operate is a temporary measure,
and long-term management and peri-
odic replanting is required to maintain
those functions of the ecosystem.
In the past, stream corridor planting
programs often included nonnative
species selected for their rapid growth
rates, soil binding characteristics, ability
to produce abundant fruits for wildlife,
or other perceived advantages over na-
tive species. These actions sometimes
have unintended consequences and
often prove to be extremely detrimental
(Olson and Knopf 1986). As a result,
many local, county, state, and federal
agencies discourage or prohibit planting
of nonnative species within wetlands or
streamside buffers. Stream corridor
restoration designs should emphasize
native plant species from local sources.
It may be feasible in some cases to focus
restoration actions on encouraging the
success of local seedfall to ensure that
locally adapted populations of stream
corridor vegetation are maintained on
the site (Friedmann et al. 1995).
Plant establishment techniques vary
greatly depending on site conditions
and species characteristics. In arid re-
gions, the emphasis has been on using
poles or cuttings of species that sprout
readily, and planting them to depths
that will ensure contact with moist soil
during the dry season (Figure 8.12).
Where water tables have declined pre-
cipitously, deep auguring and tempo-
8-16
Chapter 8: Restoration Design
-------
rary irrigation are used to establish cut-
tings and rooted or container-grown
plants. In environments where precipi-
tation or ground water is adequate to
sustain planted vegetation, prolonged
irrigation is less common, and bare-
root or container-grown plants are
often used, particularly for species that
do not sprout reliably from cuttings.
On large floodplains of the South and
East, direct seeding of acorns and plant-
ing of dormant bare-root material have
been highly successful. Other options,
such as transplanting of salvaged plants,
have been tried with varying degrees of
success. Local experience should be
sought to determine the most reliable
and efficient plant establishment ap-
proaches for particular areas and
species, and to determine what prob-
lems to expect.
It is important to protect plantings
from livestock, beaver, deer, small
mammals, and insects during the estab-
lishment period. Mortality of vegetation
from deer browsing is common and can
be prevented by using tree shelters to
protect seedlings.
Figure 8.12: Revegetation with the use of
deeply planted live cuttings. In arid regions,
poles or cuttings of species that sprout
readily are often planted to depths that
assure contact with moist soil.
Horizontal Diversity
Stream corridor vegetation, as viewed
from the air, would appear as a mosaic
of diverse plant communities that runs
from the upland on one side of the
stream corridor, down the valley slope,
across the floodplain, and up the oppo-
site slope to the upland. With such
broad dimensional range, there is a
large potential for variation in vegeta-
tion. Some of the variation is a result of
hydrology and stream dynamics, which
will be discussed later in this chapter.
Three important structural characteris-
tics of horizontal diversity of vegetation
are connectivity, gaps, and boundaries.
Connectivity and Caps
As discussed earlier, connectivity is an
important evaluation parameter of
stream corridor functions, facilitating
the processes of habitat, conduit, and
filter/barrier. Stream corridor restora-
tion design should maximize connec-
tions between ecosystem functions.
Habitat and conduit functions can be
enhanced by linking critical ecosystems
to stream corridors through design that
emphasizes orientation and proximity.
Designers should consider functional
connections to existing or potential fea-
tures such as vacant or abandoned land,
rare habitat, wetlands or meadows, di-
verse or unique vegetative communities,
springs, ecologically innovative residen-
tial areas, movement corridors for flora
and fauna, or associated stream systems.
This allows for movement of materials
and energy, thus increasing conduit
functions and effectively increasing
habitat through geographic proximity.
Generally, a long, wide stream corridor
with contiguous vegetative cover is fa-
vored, though gaps are commonplace.
The most fragile ecological functions de-
termine the acceptable number and size
of gaps. Wide gaps can be barriers to mi-
Stream corri-
dor restoration
designs should
emphasize
native plant
species from
local sources.
Plant Communities
8-17
-------
Tennessee Valley Authority Floodplain Reforestation Projects
50 Years Later
The oldest known large-scale restoration of forest-
ed wetlands in the United States was undertaken
by the Tennessee Valley Authority in conjunction
with reservoir construction projects in the South
during the 1940s. Roads and railways were relo-
cated outside the influence of maximum pool
elevations, but where they were placed on
embankments, TVA was concerned that they
would be subject to wave erosion during periods
of extreme high water. To reduce that possibility,
agricultural fields between the reservoir and the
embankments were planted with trees (Figure
8.13) At Kentucky Reservoir in Kentucky and
Tennessee, approximately 1,000 acres were plant-
Figure 8.13: Kentucky Reservoir watershed, 1943.
Planting abandoned farmland with trees.
ed, mostly on hydric soils adjacent to tributaries
of the Tennessee River. Detailed records were kept
regarding the species planted and survival rates.
Some of these stands were recently located and
studied to evaluate the effectiveness of the origi-
nal reforestation effort, and to determine the
extent to which the planted forests have come to
resemble natural stands in the area.
Because the purpose of the plantings was erosion
control, little thought was given to recreating nat-
ural patterns of plant community composition and
structure. Trees were evenly spaced in rows, and
planted species were apparently chosen for maxi-
mum flood tolerance. As a result, the studied
stands had an initial composition dominated by
bald cypress, green ash, red maple, and similarly
8-18
Chapter 8: Restoration Design
-------
water-tolerant species, but they did not originally
contain many of the other common bottomland
forest species, such as oaks.
Shear et al. (in press) compared the plant commu-
nities of the planted stands with forests on similar
sites that had been established by natural invasion
of abandoned fields. They also looked at older
stands that had never been converted to agricul-
ture. The younger planted and natural stands were
similar to the older stands with regard to understo-
ry composition, and measures of stand density and
biomass were consistent with patterns typical for
the age of the stands. Overstory composition of the
planted stands was very different from that of the
others, reflecting the original plantings. However,
both the planted sites and the fields that had been
naturally invaded had few individuals of heavy-
seeded species (oaks and hickories), which made
up 37 percent of the basal area of the older stands.
Figure 8.14: Kentucky Reservoir watershed in 1991.
Thriving bottomland hardwood forest.
Oaks are an important component of southern
bottomlands and are regarded as particularly
important to wildlife. In most modern restoration
plantings, oaks are favored on the assumption that
they will not guickly invade agricultural fields. The
stands at Kentucky Reservoir demonstrate that
planted bottomland forests can develop structural
and understory conditions that resemble those of
natural stands within 50 years (Figure 8.14).
Stands that were established by natural invasion
of agricultural fields had similar characteristics.
The major compositional deficiency in both of the
younger stands was the lack of heavy-seeded
species. The results of this study appear to support
the practice of favoring heavy-seeded species in
bottomland forest restoration initiatives.
Plant Communities
8-19
-------
Restored plant
communities
should be de-
signed to ex-
hibit structural
diversity and
canopy closure
similar to that
of the refer-
ence stream
corridor.
gration of smaller terrestrial fauna and
indigenous plant species. Aquatic fauna
may also be limited by the frequency or
dimension of gaps. The width and fre-
quency of gaps should therefore be de-
signed in response to planned stream
corridor functions. Bridges have been
designed to allow migration of animals,
along with physical and chemical con-
nections of river and wetland flow. In
Florida, for example, underpasses are
constructed beneath roadways to serve
as conduits for species movement
(Smith and Hellmund 1993). The
Netherlands has experimented with ex-
tensive species overpasses and under-
passes to benefit particular species
(Figure 8.15). Although not typically
equal to the magnitude of an undis-
turbed stream corridor lacking gaps,
these measures allow for modest func-
tions as habitat and conduit.
The filtering capacity of stream corridors
is affected by connectivity and gaps. For
example, nutrient and water discharge
flowing overland in sheet flow tends to
concentrate and form rills. These rills in
turn often form gullies. Gaps in vegeta-
tion offer no opportunity to slow over-
land flow or allow for infiltration.
Where reference dimensions are similar
and transferable, restored plant commu-
bridge
road
Figure 8.15: Underpass design. Underpasses
should be designed to accommodate both
vehicular traffic and movement of small fauna.
nities should be designed to exhibit
structural diversity and canopy closure
similar to that of the reference stream
corridor. The reference stream corridor
can provide information regarding plant
species and their frequency and distribu-
tion. Design should aim to maintain the
filtering capacity of the stream corridor
by minimizing gaps in the corridor's
width and length.
Buffer configuration and composition
have also received attention since they
influence wildlife habitat quality, in-
cluding suitability as migration corri-
dors for various species and suitability
for nesting habitat. Reestablishment of
linkages among elements of the land-
scape can be critically important for
many species (Noss 1983, Harris 1984).
However, as noted previously, funda-
mental considerations include whether
a particular vegetation type has ever
existed as a contiguous corridor in an
area, and whether the predisturbance
corridor was narrow or part of an
expansive floodplain forest system.
Establishment of inappropriate and
narrow corridors can have a net detri-
mental influence at local and regional
scales (Knopf et al. 1988). Local
wildlife management priorities should
be evaluated in developing buffer width
criteria that address these issues.
Boundaries
The structure of the edge vegetation
between a stream corridor and the adja-
cent landscape affects the habitat, con-
duit, and filter functions. A transition
between two ecosystems in an undis-
turbed environment typically occurs
across a broad area.
Boundaries between stream corridors
and adjacent landscapes may be straight
or curvilinear. A straight boundary al-
lows relatively unimpeded movement
along the edge, thereby decreasing
8-20
Chapter 8: Restoration Design
-------
species interaction between the two
ecosystems. Conversely, a curvilinear
boundary with lobes of the corridor
and adjoining areas reaching into one
another encourages movement across
boundaries, resulting in increased inter-
action. The shape of the boundary can
be designed to integrate or discourage
these interactions, thus affecting the
habitat, conduit, and filter functions.
Species interaction may or may not be
desirable depending on the project
goals. The boundary of the restoration
initiative can, for example, be designed
to capture seeds or to integrate animals,
including those carrying seeds. In some
cases, however, this interaction is dic-
tated by the functional requirements of
the adjacent ecosystem (equipment tol-
erances within an agricultural field, for
instance).
Vertical Diversity
Heterogeneity within the stream corri-
dor is an important design considera-
tion. The plants that make up the
stream corridor, their form (herbs,
shrubs, small trees, large trees), and
their diversity affect function, especially
at the reach and site scales. Stratifica-
tion of vegetation affects wind, shading,
avian diversity, and plant growth (For-
man 1995). Typically, vegetation at the
edge of the stream corridor is very dif-
ferent from the vegetation that occurs
within the interior of the corridor. The
topography, aspect, soil, and hydrology
of the corridor provide several naturally
diverse layers and types of vegetation.
The difference between edge and interior
vegetative structure are important design
considerations (Figure 8.16). An edge
that gradually changes from the stream
corridor into the adjacent ecosystems
will soften environmental gradients and
minimize any associated disturbances.
These transitional zones encourage
species diversity and buffer variable nu-
trient and energy flows. Although
human intervention has made edges
more abrupt, the conditions of naturally
occurring edge vegetation can be re-
stored through design. The plant com-
munity and landform of a restored edge
should reflect the structural variations
found in the reference stream corridor.
To maintain a connected and contigu-
ous vegetative cover at the edge of small
gaps, taller vegetation should be de-
signed to continue through the gap. If
the gap is wider than can be breached
by the tallest or widest vegetation, a
more gradual edge may be appropriate.
Vertical structure of the corridor interior
tends to be less diverse than that of the
Figure 8.16: Edge vegetative
structure. Edge characteristics
can be abrupt or gradual, with
the gradual boundary typically
encouraging more interaction
between ecosystems.
interior
Plant Communities
8-21
-------
edge. This is typically observed when
entering a woodlot: edge vegetation is
shrubby and difficult to traverse,
whereas inner shaded conditions pro-
duce a more open forest floor that al-
lows for easier movement. Snags and
downed wood may also provide impor-
tant habitat functions. When designing
to restore interior conditions of stream
corridor vegetation, a vegetation struc-
ture should be used that is less diverse
than the vegetation structure used at the
edge. The reference stream corridor will
yield valuable information for this as-
pect of design.
Influence of Hydrology and
Stream Dynamics
Natural floodplain plant communities
derive their characteristic horizontal di-
versity primarily from the organizing
influence of stream migration and
flooding (Brinson et al. 1981). As dis-
cussed earlier, when designing restora-
tion of stream corridor vegetation,
nearby reference conditions are gener-
ally used as models to identify the ap-
propriate plant species and
communities. However, the original
cover and older existing trees might
have been established before stream
regulation or other changes in the wa-
tershed that affect flow and sediment
characteristics.
A good understanding of current and
projected flooding is necessary for de-
sign of appropriately restored plant
communities within the floodplain.
Water management and planning agen-
cies are often the best sources of such
data. In wildland areas, stream gauge
data may be available, or on-site inter-
pretation of landforms and vegetation
may be required to determine whether
floodplain hydrology has been altered
through channel incision, beaver activ-
ity, or other causes. Discussions with
local residents and examination of aer-
ial photography may also provide infor-
mation on water diversions, ground
water depletion, and similar changes in
the local hydrology.
A vegetation-hydroperiod model can be
used to forecast riparian vegetation dis-
tribution (Malanson 1993). The model
identifies the inundating discharges of
various locations in the riparian zone
and the resulting suitability of moisture
conditions for desired plants. Grading
plans, for example, can be adjusted to
alter the area inundated by a given dis-
charge and thus increase the area suit-
able for vegetation associated with a
particular frequency and duration of
flooding. A focus on the vegetation-
hydroperiod relationship will demon-
strate the following:
The importance of moisture condi-
tions in structuring vegetation of the
riparian zone;
The existence of reasonably well
accepted physical models for calcu-
lating inundation from streamflow
and the geometry of the bottomland.
The likelihood that streamflow and
inundating discharges have been
altered in degraded stream systems or
will be modified as part of a restora-
tion effort.
Generally, planting efforts will be easier
when trying to restore vegetation on
sites that have suitable moisture condi-
tions for the desired vegetation, such as
in replacing historical vegetation on
cleared sites that have unaltered stream-
flow and inundating discharges. Mois-
ture suitability calculations will support
designs. Sometimes the restoration ob-
jective is to restore more of the desired
vegetation than the new flow condi-
tions would naturally support. Direct
manipulation by planting and control-
ling competition can often produce the
desired results within the physiological
tolerances of the desired species. How-
8-22
Chapter 8: Restoration Design
-------
ever, the vegetation on these sites will
be out of balance with the site moisture
conditions and might require continued
maintenance. Management of vegeta-
tion can also accelerate succession to a
more desirable state.
Projects that require long-term supple-
mental watering should be avoided due
to high maintenance costs and de-
creased potential for success. Inversely,
there may be cases where the absence of
vegetation, especially woody vegetation,
is desired near the stream channel. Al-
teration of streamflow or inundating
discharges might make moisture condi-
tions on these sites unsuitable for
woody vegetation.
The general concept of site suitability for
plant species can be extended from
moisture conditions determined by in-
undation to other variables determining
plant distribution. For example, Ohmart
and Anderson (1986) suggests that
restoration of native riparian vegetation
in arid southwestern river systems may
be limited by unsuitable soil salinities.
In many arid situations, depth to ground
water might be a more direct measure of
the moisture effects of streamflow on ri-
parian sites than actual inundation.
Both inundating discharge and depth to
ground water are strongly related to ele-
vation. However, depth to ground water
may be the more appropriate causal
variable for these rarely inundated sites,
and a physical model expressing the de-
pendence of alluvial ground water levels
on streamflow might therefore be more
important than a hydraulic model of
surface water elevations.
Some stream corridor plant species have
different requirements at different life
stages. For example, plants tolerating
extended inundation as adults may re-
quire a drawdown for establishment,
and plants thriving on relatively high
and dry sites as adults may be estab-
lished only on moist surfaces near the
water's edge. This can complicate what
constitutes suitable moisture conditions
and may require separate consideration
of establishment requirements, and per-
haps consideration of how sites might
change over time. The application of
simulation models of plant dynamics
based on solving sets of explicit rules
for how plant composition will change
over time may become necessary as in-
creasingly complex details of different
requirements at different plant life his-
tory stages are incorporated into the
evaluation of site suitability. Examples
of this type of more sophisticated plant
response model include van der Valk
(1981) for prairie marsh species and
Pearlstine et al. (1985) for bottomland
hardwood tree species.
Soil Bioengineering for
Floodplains and Uplands
Soil bioengineering is the use of live and
dead plant materials, in combination
with natural and synthetic support ma-
terials, for slope stabilization, erosion
reduction, and vegetative establishment.
There are many soil bioengineering sys-
tems, and selection of the appropriate
system or systems is critical to success-
ful restoration. Reference documents
should be consulted to ensure that the
principles of soil bioengineering are un-
derstood and applied. The NRCS Engi-
neering Field Handbook, Part 650
[Chapter 16, Streambank and Shoreline
Protection (USDA-NRCS 1996) and
Chapter 18, Soil Bioengineering for Up-
land Slope Protection and Erosion Re-
duction (USDA-NRCS 1992)] offers
background and guidelines for applica-
tion of this technology. A more detailed
description of soil bioengineering sys-
tems is offered in Section 8.F, Stream-
bank Stabilization Design, of this
chapter and in Appendix A.
FAST
FORWARD
Preview Chap-
ter 8, Section F
for more infor-
mation on soil
bioengineering
techniques.
Plant Communities
8-23
-------
8.D Habitat Measures
Figure 8.17: Bottom-
land hardwoods
serving as a green-
tree reservoir. Proper
management of
greentree reservoirs
requires knowledge
of the local system.
Other measures may be used to provide
structure and functions. They may be
implemented as separate actions or as
an integral part of the restoration plan
to improve habitat, in general, or for
specific species. Such measures can pro-
vide short-term habitat until overall
restoration results reach the level of
maturity needed to provide the desired
habitat. These measures can also pro-
vide habitat that is in short supply.
Greentree reservoirs, nest structures,
and food patches are three examples.
Beaver are also presented as a restora-
tion measure.
Greentree Reservoirs
Short-term flooding of bottomland
hardwoods during the dormant period
of tree growth enhances conditions for
some species (e.g., waterfowl) to feed on
mast and other understory food plants,
like wild millet and smartweed. Acorns
are a primary food source in stream cor-
ridors for a variety of fauna, including
ducks, nongame birds and mammals,
turkey, squirrel, and deer. Greentree
reservoirs are shallow, forested flood-
plain impoundments usually created by
building low levees and installing outlet
structures (Figure 8.17). They are usu-
ally flooded in early fall and drained
during late March to mid-April. Drain-
ing prevents damage to overstory hard-
woods (Rudolph and Hunter 1964).
Most existing greentree reservoirs are in
the Southwest.
The flooding of greentree reservoirs, by
design, differs from the natural flood
regime. Greentree reservoirs are typi-
cally flooded earlier and at depths
greater than would normally occur
under natural conditions. Over time,
modifications of natural flood condi-
tions can result in vegetation changes,
lack of regeneration, decreased mast
production, tree mortality, and disease.
Proper management of green tree reser-
voirs requires knowledge of the local
systemespecially the natural flood
regimeand the integration of manage-
ment goals that are consistent with
system requirements. Proper manage-
ment of greentree reservoirs can provide
8-24
Chapter 8: Restoration Design
-------
quality habitat on an annual basis, but
the management plan must be well
designed from construction through
management for waterfowl.
Nest Structures
Loss of riparian or terrestrial habitat in
stream corridors has resulted in the de-
cline of many species of birds and
mammals that use associated trees and
tree cavities for nesting or roosting. The
most important limiting factor for
cavity-nesting birds is usually the avail-
ability of nesting substrate (von Haart-
man 1957), generally in the form of
snags or dead limbs in live trees (Sedg-
wick and Knopf 1986). Snags for nest
structures can be created using explo-
sives, girdling, or topping of trees. Arti-
ficial nest structures can compensate
for a lack of natural sites in otherwise
suitable habitat since many species of
birds will readily use nest boxes or
other artificial structures. For example,
along the Mississippi River in Illinois
and Wisconsin, where nest trees have
become scarce, artificial nest structures
have been erected and constructed for
double-crested cormorants using utility
poles (Yoakum et al. 1980). In many
cases, increases in breeding bird density
have resulted from providing such struc-
tures (Strange et al. 1971, Brush 1983).
Artificial nest structures can also im-
prove nestling survival (Cowan 1959).
Nest structures must be properly de-
signed and placed, meeting the biologi-
cal needs of the target species. They
should also be durable, predator-proof,
and economical to build. Design speci-
fications for nest boxes include hole di-
ameter and shape, internal box volume,
distance from the floor of the box to
the opening, type of material used,
whether an internal "ladder" is neces-
sary, height of placement, and habitat
type in which to place the box. Other
types of nest structures include nest
platforms for waterfowl and raptors;
nest baskets for doves, owls, and water-
fowl; floating nest structures for geese;
and tire nests for squirrels. Specifica-
tions for nest structures for riparian and
wetland nesting species (including nu-
merous Picids, passerines, waterfowl,
and raptors) can be found in many
sources including Yoakum et al. (1980),
Kalmbach et al. (1969), and various
state wildlife agency and conservation
publications.
Food Patches
Food patch planting is often expensive
and not always predictable, but it can
be carried out in wetlands or riparian
systems mostly for the benefit of water-
fowl. Environmental requirements of
the food plants native to the area,
proper time of year of introduction,
management of water levels, and soil
types must all be taken into considera-
tion. Some of the more important food
plants in wetlands include pondweed
(Potamogeton spp.), smartweed (Poly-
go num spp.), duck potato, spike sedges
(Carex spp.), duckweeds (Lemna spp.),
coontail, alkali bulrush (Scirpus palu-
dosus), and various grasses. Two com-
monly planted native species include
wild rice (Zizania) and wild millet. De-
tails on suggested techniques for plant-
ing these species can be found in
Yoakum et al. (1980).
Habitat Measures
8-25
-------
Importance of Beaver to Riparian
Ecosystems
Beaver have long been recognized for their poten-
tial to influence riparian systems. In rangelands,
where loss of riparian functional value has been
most dramatic, the potential role of beaver in
restoring degraded streams is least understood.
Beaver dams on headwater streams can positively
influence riparian function in many ways, as summa-
rized by Olson and Hubert (1994) (Figure 8.18). They
improve water quality by trapping sediments behind
dams and by reducing stream velocity, thereby
reducing bank erosion (Parker 1986). Beaver ponds
Figure 8.18: Beaver dam on a headwater stream. Beavers
have many positive impacts on headwater streams.
can alter water chemistry by changing adsorption
rates for nitrogen and phosphorus (Maret 1985) and
by trapping coliform bacteria (Skinner et al. 1984).
The flow regime within a watershed can also be
influenced by beaver. Beaver ponds create a sponge-
like effect by increasing the area where soil and
water meet (Figure 8.19). Headwaters retain more
water from spring runoff and major storm events,
which is released more slowly, resulting in a higher
water table and extended summer flows. This
increase in water availability, both surface and subsur-
face, usually increases the width of the riparian zone
and, consequently, favors wildlife communities that
depend on that vegetation. There can be negative
impacts as well, including loss of spawning habitat,
increase in water temperatures beyond optimal levels
for some fish species, and loss of riparian habitat.
Richness, diversity, and abundance of birds, her-
petiles, and mammals can be increased by the activ-
ities of beaver (Baker et al. 1992, Medin and Clary
1990). Beaver ponds are important waterfowl pro-
duction areas and can also be used during migra-
tion (Call 1970, Ringelman 1991). In some high-ele-
vation areas of the Rocky Mountains, beaver are
solely responsible for the majority of local duck pro-
duction. In addition, species of high interest, such as
trumpeter swans, sandhill cranes, moose, mink, and
river otters, use beaver ponds for nesting or feeding
areas (Collins 1976).
Transplanting Beaver to Restore
Stream Functions
Beaver have been successfully transplanted into
many watersheds throughout the United States dur-
ing the past 50 years. This practice was very com-
mon during the 1950s after biologists realized the
loss of ecological function resulting from overtrap-
ping of beaver by fur traders before the turn of the
century. Reintroduction of beaver has restored the
U.S. beaver population to 6-12 million, compared to
a pre-European level of 60-400 million (Naiman et
al. 1986). Much unoccupied habitat or potential
habitat still remains, especially in the shrub-steppe
ecosystem.
In forested areas, where good beaver habitat already
exists, reintroduction techniques are well established.
The first question asked should be "If the habitat is
suitable, why are beaver absent?" In the case of
newly restored habitat or areas far from existing
populations, reintroduction without habitat improve-
ment might be warranted (Figure 8.20). Beavers are
livetrapped from areas
that have excess popu-
lations or from areas
where they are a nui-
sance. It is advisable to
obtain beavers from
habitat that is similar to
where they will be
introduced to ensure
Figure 8.19: A beaver
pond. Beaver ponds cre-
ate a sponge-like effect.
8-26
Chapter 8: Restoration Design
-------
Figure 8.20: Beaver habitat. It is advisable to obtain
beaver from habitat that is similar to where they will
be introduced.
they are familiar with available food and building
materials (Smith and Prichard 1992). This is particu-
larly important in shrub-steppe habitats.
Reintroduction into degraded riparian areas within
the shrub-steppe zone is controversial. Convention-
al wisdom holds that a yearlong food supply must
be present before introducing beaver. In colder cli-
mates, this means plants with edible bark, such as
willow, cottonwood, or aspen, must be present to
provide a winter food supply for beaver (Figure
8.21). But often these species are the goal of
restoration. In some cases willows or other species
can be successfully planted as described in other
sections of this document. In other areas, condi-
tions needed to sustain planted cuttings, such as a
high water table and minimal competition with
other vegetation, might preclude successful estab-
lishment. Transplanting beaver before willows are
established may create the conditions needed to
both establish and maintain riparian shrubs or trees.
In these cases it may be helpful to provide beaver
with a pickup truck load of aspen or other trees to
use as building material at or near the reintroduc-
tion site. This may encourage beaver to stay near
the site and strengthen dams built of sagebrush or
other shrubs (Apple et al. 1985).
Nuisance Beaver
Unfortunately, beaver are not beneficial in all situa-
tions, which is all too obvious to those managing
damage control. In many cases where they live in
dose proximity to humans or features important to
humans, beaver need to be removed or their dam-
age controlled. Common problems include cutting
or eating desirable vegetation, flooding roads or
irrigation ditches by plugging culverts, and increas-
ing erosion by burrowing into the banks of streams
or reservoirs. In addition, beaver carry Giardia
species pathogens, which can infect drinking water
supplies and cause human health problems.
Control of nuisance beaver usually involves remov-
ing the problem animals directly or modifying their
habitat. Beaver can be livetrapped (Bailey or Han-
cock traps) and relocated to a more acceptable
location or killed by dead-traps (e.g., Conibear
#330) or shooting (Miller
1983). In cases where the
water level in a dam must
be controlled to prevent
flooding, a pipe can be
placed through the dam
with the upstream side per-
forated to allow water flow.
Figure 8.21: A beaver lodge.
The living chamber in a beaver
lodge is above water and used
year-round. Deep entrances
enable beavers to obtain
food from underwater caches
in winter.
Habitat Measures
8-27
-------
8.E Stream Channel Restoration
Review Chapter
4's Data Collec-
tion Planning
section.
Some disturbances to stream channels
(e.g., from surface mining activities, ex-
treme weather events, or major highway
construction) are so severe that restora-
tion within a desired time frame re-
quires total reconstruction of a new
channel. Selecting dimensions (width,
depth, cross-sectional shape, pattern,
slope, and alignment) for such a recon-
structed channel is perhaps the most
difficult component of stream restora-
tion design. In the case of stream chan-
nel reconstruction, stream corridor
restoration design can proceed along
one of two broad tracks:
1. A single-species restoration that
focuses on habitat requirements of
certain life stages of species (for
example, rainbow trout spawning).
The existing system is analyzed in
light of what is needed to provide a
given quantity of acceptable habitat
for the target species and life stage,
and design proceeds to remedy any
deficiencies noted.
2. An "ecosystem restoration" or
"ecosystem management" approach
that focuses design resources on the
chemical, hydrologic, and geomor-
phic functions of the stream corridor.
This approach assumes that commu-
nities will recover to a sustainable
level if the stream corridor structure
and functions are adequate. The
strength of this approach is that it
recognizes the complex interdepen-
dence between living things and the
totality of their environments.
Although methods for single-species
restoration design pertaining to treat-
ments for aquatic habitat are included
elsewhere in this chapter, the second
track is emphasized in this section.
Procedures for Channel
Reconstruction
If watershed land use changes or other
factors have caused changes in sediment
yield or hydrology, restoration to an
historic channel condition is not rec-
ommended. In such cases, a new chan-
nel design is needed. The following
procedures are suggested:
1. Describe physical aspects of the
watershed and characterize its hydro-
logic response.
This step should be based on data
collected during the planning phase,
as described in Chapter 4.
2. Considering reach and associated
constraints, select a preliminary
right-of-way for the restored stream
channel corridor and compute the
valley length and valley slope.
3. Determine the approximate bed
material size distribution for the new
channel.
Many of the channel design procedures
described below require the designer to
supply the size of bed sediments. If the
project is not likely to modify bed sedi-
ments, the existing channel bed may be
sampled using procedures reviewed in
Chapter 7. If predisturbance conditions
were different from those of the existing
channel, and if those conditions must
be restored, the associated sediment
size distribution must be determined.
This can be done by collecting represen-
tative samples of bed sediments from
nearby, similar streams; by excavating to
locate the predisturbance bed; or by ob-
taining the information from historic
resources.
Like velocity and depth, bed sediment
size in natural streams varies continu-
8-28
Chapter 8: Restoration Design
-------
ously in time and space. Particularly
troublesome are streams with sediment
size distributions that are bimodal mix-
tures of sand and gravel, for example.
The median (D ) of the overall distrib-
ution might be virtually absent from
the bed. However, if flow conditions
allow development of a well-defined
armor layer, it might be appropriate to
use a higher percentile than the median
(e.g., the D75 ) to represent the bed ma-
terial size distribution. In some cases, a
new channel excavated into a heteroge-
neous mixture of noncohesive material
will develop an armor layer. In such a
case, the designer must predict the
likely size of the armor layer material.
Methods presented by Helwig (1987)
and Griffiths (1981) could prove help-
ful in such a situation.
4. Conduct a hydrologic and hydraulic
analysis to select a design discharge
or range of discharges.
Conventional channel design has re-
volved around selecting channel dimen-
sions that convey a certain discharge at
or below a certain elevation. Design dis-
charge is usually based on flood fre-
quency or duration or, in the case of
canals, on downstream supply needs.
Channel restoration, on the other hand,
implies designing a channel similar to
one that would develop naturally under
similar watershed conditions.
Therefore, the first step in selecting a de-
sign discharge for restoration is not to
determine the controlling elevation for
flood protection but to determine what
discharge controls channel size. Often
this will be at or close to the 1- to 3-year
recurrence interval flow. See Chapters 1
and 7 for discussions of channel-form-
ing, effective, and design discharges. Ad-
ditional guidance regarding streamflow
analysis for gauged and ungauged sites
is presented in Chapter 7. The designer
should, as appropriate to the stream sys-
tem, compute effective discharge or esti-
mate bankfull discharge.
A sediment rating curve must be devel-
oped to integrate with the flow dura-
tion curve to determine the effective
discharge. The sediment load that is re-
sponsible for shaping the channel (bed
material load) should be used in the
calculation of the effective discharge.
This sediment load can be determined
from measured data or computed using
an appropriate sediment transport
equation. If measured suspended sedi-
ment data are used, the wash load, typi-
cally consisting of particles less than
0.062 mm, should be deleted and only
the suspended bed material portion of
the suspended load used. If the bed
load in the stream is considered to be
only a small percentage of the total bed
material load, it might be acceptable to
simply use the measured suspended
bed material load in the effective dis-
charge calculations. However, if the bed
load is a significant portion of the load,
it should be calculated using an appro-
priate sediment transport function and
then added to the suspended bed mate-
rial load to provide an estimate of the
total bed material load. If bed load
measurements are available, which sel-
dom is the case, these observed data
can be used.
Flow levels and frequencies that cause
flooding also need to be identified to
help plan and design out-of-stream
restoration measures in the rest of the
stream corridor. If flood management is
a constraint, additional factors that are
beyond the scope of this document
enter the design. Environmental fea-
tures for flood control channels are de-
scribed elsewhere (Hey 1995, Shields
and Aziz 1992, USAGE 1989a, Brookes
1988).
Channel reconstruction and stream cor-
ridor restoration are most difficult for
REVERSE
Review Chapter
1 and Chapter
7's channel-
forming,
effective,
and design
discharges
sections.
Stream Channel Restoration
8-29
-------
REVERSE
Review Chapter
7's hydrologic
analysis and
stage-discharge
relationships
sections.
incised streams, and hydrologic analy-
ses must consider several additional fac-
tors. Incised stream channels are
typically much larger than required to
convey the channel-forming discharge.
Restoration of an incised channel may
involve raising the bottom of a stream
to restore overbank flow and ecological
functions of the floodplain. In this type
of restoration, compatibility of restored
floodplain hydrology with existing land
uses must be considered.
A second option in reconstructing in-
cised channels is to excavate one or
both sides to create a new bankfull
channel with a floodplain (Hey 1995).
Again, adjacent land uses must be able
to accommodate the new, excavated
floodplain/channel.
A third option is to stabilize the incised
channel in place, and to enhance the
low-flow channel for environmental
benefits. The creation of a floodplain
might not be necessary or possible as
part of a stream restoration.
In cases where channel sizing, modifi-
cation, or realignment are necessary, or
where structures are required to en-
hance vertical or lateral stability, it is
critical that restoration design also in-
clude consideration of the range of
flows expected in the future. In urbaniz-
ing watersheds, future conditions may
be quite different from existing condi-
tions, with higher, sharper, peak flows.
If certain instream flow levels are re-
quired to meet restoration objectives, it
is imperative that those flows be quan-
tified on the basis of a thorough under-
standing of present and desired
conditions. Good design practice also
requires checking stream channel hy-
draulics and stability at discharges well
above and below the design condition.
Stability checks (described below) may
be quite simple or very sophisticated.
Additional guidance on hydrologic
analysis and development of stage-
discharge relationships are presented
in Chapter 7.
5. Predict stable planform type
(straight, meandering, or braided).
Channel planform may be classified as
straight, braided, or meandering, but
thresholds between categories are arbi-
trary since channel form can vary contin-
uously from straight to single-channel
meanders to multiple braids. Naturally
straight, stable alluvial channels are rare,
but meandering and braided channels
are common and can display a wide
range of lateral and vertical stability.
Relationships have been proposed that
allow prediction of channel planform
based on channel slope, discharge, and
bed material size (e.g., Chang 1988),
but they are sometimes unreliable (Chi-
tale 1973, Richards 1982) and give
widely varying estimates of the slope
threshold between meandering and
braiding. As noted by Dunne (1988),
"The planform aspects of rivers are the
most difficult to predict," a sentiment
echoed by USAGE (1994), "... available
analytical techniques cannot determine
reliably whether a given channel modi-
fication will be liable to meander devel-
opment, which is sensitive to
difficult-to-quantify factors like bank
vegetation and cohesion."
Stable channel bed slope is influenced
by a number of factors, including sedi-
ment load and bank resistance to ero-
sion. For the first iteration, restoration
designers may assume a channel plan-
form similar to stable reference chan-
nels in similar watersheds. By
collecting data for stable channels and
their valleys in reference reaches, in-
sight can be gained on what the stable
configuration would be for the restora-
tion area. The morphology of those
stream types can also provide guidance
or additional converging lines of evi-
8-30
Chapter 8: Restoration Design
-------
dence that the planform selected by the
designer is appropriate.
After initial completion of these five
steps, any one of several different paths
may be taken to final design. Three ap-
proaches are summarized in Table 8.1.
The tasks are not always executed se-
quentially because trial and error and
reiteration are often needed.
Alignment and Average Slope
In some cases, it might be desirable
to divert a straightened stream into a
meandering alignment for restoration
purposes. Three approaches for mean-
der design are summarized in the adja-
cent box.
For cases where the design channel will
carry only a small amount of bed mate-
(Approach A
Task !
Determine
meander
geometry
and channel
alignment.1
Compute
sinuosity,
channel
length, and
slope.
Compute
mean flow
width and
depth at
design
discharge."
Compute
riffle spacing
(if gravel
bed), and add
detail to
design.
Check
channel
stability and
reiterate as
needed.
(Approach B (Hey 1994)
Empirical formulas
for meander
wavelength, and
adaptation of
measurements from
predisturbed
conditions or nearly
undisturbed reaches.
Channel length =
sinuosity X valley
length. Channel
slope= valley slope/
sinuosity.
Regime or hydraulic
geometry formulas
with regional
coefficients, and
resistance equations
or analytical
methods (e.g.
tractive stress, Ikeda
and Izumi, 1990, or
Chang, 1988).
Empirical formulas.
observation of
similar streams,
habitat criteria.
Check stability.
I Task
Determine bed
material
discharge to be
carried by design
channel at design
discharge.
compute bed
material sediment
concentration.
Compute mean
flow, width,
depth, and slope
at design
discharge."
Compute
sinuosity and
channel length.
Determine
meander
geometry and
channel
alignment.
Compute riffle
spacing (if gravel
bed), and add
detail to design.
Check channel
stability and
reiterate as
needed.
Tools
Analyze measured
data or use
appropriate
sediment transport
function2 and
hydraulic properties
of reach upstream
from design reach.
Regime or hydraulic
geometry formulas
with regional
coefficients, or
analytical methods
(e.g. White, et.al..
1982, orCopeland,
1994).3
Sinuosity = valley
slope/ channel
slope.
Channel length=
sinuosity X valley
length.
Lay out a piece of
string scaled to
channel length on a
map (or equivalent
procedure) such
that meander arc
lengths vary from 4
to 9 channel widths.
Empirical formulas,
observation of
similar streams,
habitat criteria.
Check stability.
(Approach C (Fogg 1995) I
Task
Compute
mean flow,
width, depth,
and slope at
design
discharge.4
Compute or
estimate flow
resistance
coefficient at
design
discharge.
Compute
mean channel
slope and
depth
required to
pass design
discharge.
Compute
velocity or
boundary
sheer stress at
design
discharge.
Compute
sinuosity and
channel
length.
Compute
sinuosity and
channel
length.
Check channel
stability and
reiterate as
needed.
I Tools I
Regime or hydraulic
geometry formulas
with regional
coefficients.
Appropriate
relationship between
depth, bed sediment
size, and resistance
coefficient, modified
based on expected
sinuosity and
bank/berm vegetation.
Uniform flow equation
(e.g. Manning, Chezy)
continuity equation,
and design channel
cross-sectional shape;
numerical water
surface profile models
may be used instead of
uniform flow equation.
Allowable velocity or
shear stress criteria
based on channel
boundary materials.
Sinuosity = valley
slope/ channel slope.
Channel length=
sinuosity X valley
length.
Lay out a piece of
string scaled to
channel length on a
map (or equivalent
procedure) such that
meander arc lengths
vary from 4 to 9
channel widths.
Check stability.
Table 8.1 .-Three
approaches to
achieving final
design. There are
variations of the
final steps to a
restoration design,
after the first five
steps described in
the text are done.
1 Assumes meandering planform would be stable. Sinuosity and arc-length are known.
2 Computation of sediment transport without calibration against measured data may give highly unreliable results for a specific channel
(USAGE, 1994, Kuhnle, etal., 1989).
3 The two methods listed assume a straight channel. Adjustments would be needed to allow for effects of bends.
4 Mean flow width and depth at design discharge will give channel dimensions since design discharge is bankfull. In some situations channel may be increased to
allow for freeboard. Regime and hydraulic geometry formulas should be examined to determine if they are mean width or top width.
Stream Channel Restoration
8-31
-------
USAGE Channel Restoration
Design Procedure
A systematic design methodology has been developed fo>
use in designing restoration projects that involve channel
reconstruction (USACE, WES). The methodology includes
use of hydraulic geometry relationships, analytical determi-
nation of stable channel dimensions, and a sediment
impact assessment. The preferred geometry is a compound
channel with a primary channel designed to carry the effec-
tive or "channel forming" discharge and an overbank area
designed to carry the additional flow for a specified flood
discharge. Channel width may be determined by analogy
methods, hydraulic geometry predictors, or analytically.
Currently under development are hydraulic geometry pre-
dictors for various stream types. Once a width is determined
for the effective discharge, depth and channel slope are
determined analytically by balancing sediment inflow from
upstream with sediment transport capacity through the
restored channel. Meander wavelength is determined by
analogy or hydraulic geometry relationships. Assumption of
a sine-generated curve then allows calculation of channel
planform. The stability of the channel design is then evalu-
ated for the full range of expected discharges by conduct-
ing a sediment impact assessment. Refinements to the
design include variation of channel widths at crossings and
pools, variable lateral depths in pools, coarsening of the
channel bed in riffles, and bank protection.
rial load, bed slope and channel dimen-
sions may be selected to carry the de-
sign discharge at a velocity that will be
great enough to prevent suspended sed-
iment deposition and small enough to
prevent erosion of the bed. This ap-
proach is suitable only for channels
with beds that are stationary or move
very infrequentlytypically stable
cobble- and gravel-bed streams.
Once mean channel slope is known,
channel length can be computed by
multiplying the straight line down-
valley distance by the ratio of valley
slope to channel slope (sinuosity).
Meanders can then be laid out using a
piece of string on a map or an equiva-
lent procedure, such that the meander
arc length L (the distance between in-
flection points, measured along the
channel) ranges from 4 to 9 channel
widths and averages 7 channel widths.
Meanders should not be uniform.
The incised, straightened channel of the
River Blackwater (Norfolk, United King-
dom) was restored to a meandering
form by excavating a new low-level
floodplain about 50 to 65 feet wide
containing a sinuous channel about 16
feet wide and 3 feet deep (Hey 1995).
Preliminary calculations indicated that
the bed of the channel was only slightly
mobile at bankfull discharge, and sedi-
ment loads were low. A carbon copy de-
sign process was used, recreating
meander geometry from the mid-19th
century (Hey 1994). The River Neath
(Wales, United Kingdom), an active
gravel-bed stream, was diverted at five
locations into meandering alignments
to allow highway construction. Existing
slopes were maintained through each
diversion, effectively illustrating a
"slope-first" design (Hey 1994).
Channel Dimensions
Selection of channel dimensions in-
volves determining average values for
width and depth. These determinations
are based on the imposed water and
sediment discharge, bed sediment size,
bank vegetation, resistance, and average
bed slope. However, both width and
depth may be constrained by site fac-
tors, which the designer must consider
once stability criteria are met. Channel
width must be less than the available
corridor width, while depth is depen-
dent on the upstream and downstream
controlling elevations, resistance, and
the elevation of the adjacent ground
surface. In some cases, levees or flood-
walls might be needed to match site
constraints and depth requirements.
Average dimensions determined in this
8-32
Chapter 8: Restoration Design
-------
step should not be applied uniformly.
Instead, in the detailed design step de-
scribed below, nonuniform slopes and
cross sections should be specified to
create converging and diverging flow
and resulting physical diversity.
The average cross-sectional shape of
natural channels is dependent on dis-
charge, sediment inflow, geology, rough-
ness, bed slope, bank vegetation, and
bed and bank materials. Although bank
vegetation is considered when using
some of the empirical tools presented
below, many of the analytical ap-
proaches do not consider the influence
of bank material and vegetation or make
unrealistic assumptions (e.g., banks are
composed of the same material as the
bed). These tools should be used with
care. After initial selection of average
channel width and depth, designers
should consider the compatibility of
these dimensions with reference reaches.
Reference Reaches
Perhaps the simplest approach to select-
ing channel width and depth is to use
dimensions from stable reaches else-
where in the watershed or from similar
reaches in the region. The difficulty in
this approach is finding a suitable refer-
ence reach. A reference reach is a reach
of stream outside the project reach that
is used to develop design criteria for the
project reach.
A reference reach used for stable chan-
nel design should be evaluated to make
sure that it is stable and has a desirable
morphological and ecological condi-
tion. In addition, the reference reach
must be similar enough to the desired
project reach so that the comparison is
valid. It must be similar to the desired
project reach in hydrology, sediment
load, and bed and bank material.
The term reference reach has several
meanings. As used above, the reference
reach is a reach that will be used as a
template for the geometry of the re-
stored channel. The width, depth, slope,
and planform characteristics of the refer-
ence reach are transferred to the design
reach, either exactly or by using analyti-
cal or empirical techniques to scale
them to fit slightly different characteris-
tics of the project reach (for example, a
larger or smaller drainage area).
It is impossible to find an exact replica
of the watershed in which the restora-
tion work is located, and subjective
judgement may play a role in determin-
ing what constitutes similarity. The level
of uncertainty involved may be reduced
by considering a large number of stable
reaches. By classifying the reference
streams, width and depth data can be
grouped by stream type to reduce the
scatter inherent in regional analyses.
A second common meaning of the term
reference reach is a reach with a desired
biological condition, which will be
used as a target to strive for when com-
paring various restoration options. For
instance, for a stream in an urbanized
area, a stream with a similar drainage
area in a nearby unimpacted watershed
might be used as a reference reach to
show what type of aquatic and riparian
community might be possible in the
project reach. Although it might not be
possible to return the urban stream to
predevelopment conditions, the charac-
teristics of the reference reach can be
used to indicate what direction to move
toward. In this use of the term, a refer-
ence reach defines desired biological
and ecological conditions, rather than
stable channel geometry. Modeling
tools such as IFIM and RCHARC (see
Chapter 7) can be used to determine
what restoration options come closest
to replicating the habitat conditions of
the reference reach (although none of
the options may exactly match it).
Stream Channel Restoration
8-33
-------
Meander Design
Five approaches to meander design are described
below, not in any intended order of priority. The
first four approaches result in average channel
slope being determined by meander geometry.
These approaches are based on the assumption
that the controlling factors in the stream channel
(water and sediment inputs, bed material grada-
tion, and bank erosional resistance) will be similar
to those in the reference reach (either the restora-
tion reach before disturbance or undisturbed
reaches). The fifth approach requires determina-
tion of stream channel slope first. Sinuosity follows
as the ratio of channel slope to valley slope, and
meander geometry (Figure 8.22) is developed to
obtain the desired sinuosity.
1. Replacement of meanders exactly as found
before disturbance (the carbon copy tech-
nique). This method is appropriate if hydrology
and bed materials are very similar or identical to
predisturbance conditions. Old channels are
often filled with cohesive soils and may have
cohesive boundaries. Accordingly, channel sta-
bility may be enhanced by following a previous
channel alignment.
2. Use of empirical relationships that allow
computation of meander wavelength, L,
and amplitude based on channel width or
discharge. Chang (1988) presents graphical
and algebraic relationships between meander
wavelength, width-depth ratio, and friction
factor. In addition to meander wavelength,
specification of channel alignment requires
meander radius of curvature (Hey 1976) and
meander amplitude or channel slope. Hey
(1976) also suggests that L is not usually
uniquely determined by channel width or dis-
charge. Rechard and Schaefer (1984) provide
an example of development of regional formu-
las for meander restoration design. Chapter 7
includes a number of meander geometry rela-
tionships developed from regional data sets.
Newbury and Gaboury (1993) designed mean-
ders for a straightened stream (North Pine River)
by selecting meander amplitude to fit between
floodplain terraces. Meander wavelength was
set at 12.4 times the channel width (on the
high end of the literature range), and radius
of curvature ranged from 1.9 to 2.3 times the
channel width.
L meander wavelength
ML meander arc length
w average width at bankfull discharge
MA meander amplitude
rc radius of curvature
e arc angle
Figure 8.22: Variables used to describe and design
meanders. Consistent, clear terminology is used in
meander design.
Adapted from Williams 1986.
8-34
Chapter 8: Restoration Design
-------
3. Basin-wide analysis to determine funda-
mental wavelength, mean radius of curva-
ture, and meander belt width in areas "rea-
sonably free of geologic control." This
approach has been used for reconstruction of
streams destroyed by surface mining in subhu-
mid watersheds of the western United States.
Fourier analysis may be used with data digitized
from maps to determine fundamental meander
wavelength (Hasfurther 1985).
4. Use of undisturbed reaches as design mod-
els. If the reach targeted for restoration is close-
ly bounded by undisturbed meanders, dimen-
sions of these undisturbed reaches may be stud-
ied for use in the restored reach (Figure 8.23).
Hunt and Graham (1975) describe successful
use of undisturbed reaches as models for design
and construction of two meanders as part of
river relocation for highway construction in
Montana. Brookes (1990) describes restoration
of the Elbaek in Denmark using channel width,
depth, and slope from a "natural" reach down-
stream, confirmed by dimensions of a river in a
neighboring watershed with similar area, geolo-
gy, and land use.
5. Slope first. Hey (1994) suggests that meanders
should be designed by first selecting a mean
channel slope based on hydraulic geometry for-
mulas. However, correlation coefficients for
regime slope formulas are always much smaller
than those for width or depth formulas, indicat-
ing that the former are less accurate. Channel
slope may also be determined by computing the
value required to convey the design water and
sediment discharges (White et al. 1982,
Cope/and 1994). The main weakness of this
approach is that bed material sediment dis-
charge is required by analytical techniques and
in some cases (e.g., Hey and Thome 1986) by
hydraulic geometry formulas. Sediment dis-
charges computed without measured data for
calibration may be unreliable.
Site-specific bed material samples and
channel geometries are needed to apply
these analytical techniques and to achieve
confidence in the resulting design.
Figure 8.23: The natural meander
of a stream. Rivers meander to
increase length and reduce gradi-
ent. Stream restorations often
attempt to reconstruct the chan-
nel to a previous meandering con-
dition or one "copied" from a ref-
erence reach.
Stream Channel Restoration
8-35
-------
Application of Regime and
Hydraulic Geometry Approaches
Typical regime and hydraulic geometry
relationships are presented in Chapter
7. These formulas are most reliable for
width, less reliable for depth, and least
reliable for slope.
Exponents and coefficients for hydraulic
geometry formulas are usually deter-
mined from data for the same stream,
the same watershed, streams of a simi-
lar type, or the same physiographic re-
gion. Because formula coefficients vary,
application of a given set of hydraulic
geometry or regime relationships
should be limited to channels similar
to the calibration sites. Classifying
streams can be useful in refining regime
relationships (See Chapter 7's section
on Stream Classification).
Published hydraulic geometry relation-
ships are usually based on stable, sin-
gle-thread alluvial channels. Hydraulic
geometry relationships determined
through stream classification of refer-
ence reaches can also be valuable for
designing the stream restoration. Chan-
nel geometry-discharge relationships
are more complex for multithread chan-
nels. Individual threads may fit the rela-
tionships if their partial bankfull
discharges are used in place of the total
streamflow. Also, hydraulic geometry re-
lationships for gravel-bed rivers are far
more numerous in the literature than
those for sand-bed rivers.
A trial set of channel properties (aver-
age width, depth, and slope) can be
evaluated by using several sets of
regime and hydraulic geometry formu-
las and comparing results. Greatest
weight should be given to formulas
based on sites similar to the project
reach. A logical second step is to use
several discharge levels in the best-
suited sets of formulas. Because hy-
draulic geometry relationships are
most compatible with single-channel
sand and gravel streams with low bed-
material sediment discharge, unstable
channels (aggrading or degrading pro-
files) can depart strongly from pub-
lished relationships.
Literature references to the use of hy-
draulic geometry formulas for sizing
restored channels are abundant. Initial
estimates for width and depth for the
restored channel of Seminary Creek,
which drains an urban watershed in
Oakland, California, were determined
using regional hydraulic geometry for-
mulas (Riley and MacDonald 1995).
Hey (1994, 1995) discusses use of hy-
draulic geometry relationships deter-
mined using regression analyses of data
from gravel bed rivers in the United
Kingdom for restoration design. New-
bury and Gaboury (1993) used regional
hydraulic geometry relations based on
drainage area to check width and depth
of restored channels in Manitoba.
Hydraulic geometry formulas for sizing
stream channels in restoration efforts
must be used with caution since a num-
ber of pitfalls are associated with their
use:
The formulas represent hydraulic
geometry only at bankfull or mean
annual discharge. Designers must
also select a single statistic to
describe bed sediment size when
using hydraulic geometry relation-
ships. (However, refinements to the
Hey and Thorne [1986] formulas for
slope in Table 7.5 should be noted.)
Downstream hydraulic geometry for-
mulas are usually based on the bank-
full discharge, the elevation of which
can be extremely difficult to identify
in vertically unstable channels.
Exponents and coefficients selected
for design must be based on streams
with slopes, bed sediments, and bank
8-36
Chapter 8: Restoration Design
-------
materials similar to the one being
designed.
The premise is that the channel
shape is dependent on only one or
two variables.
Hydraulic geometry relationships are
power functions with a fair degree of
scatter that may prove too great for
reliable engineering design. This scat-
ter is indicative of natural variability
and the influence of other variables
on channel geometry.
In summary, hydraulic geometry rela-
tionships are useful for preliminary or
trial selection of design channel proper-
ties. Hydraulic and sediment transport
analyses are recommended for final de-
sign for the restoration.
Analytical Approaches for
Channel Dimensions
Analytical approaches for designing
stream channels are based on the idea
that a channel system may be described
by a finite number of variables. In most
practical design problems, a few vari-
ables are determined by site conditions
(e.g., valley slope and bed material
size), leaving up to nine variables to be
computed. However, designers have
only three governing equations avail-
able: continuity, flow resistance (such as
Manning, Chezy, and Darcy-Weisbach),
and sediment transport (such as Ackers-
White, Einstein, and Brownlie). Since
this leaves more unknowns than there
are equations, the system is indetermi-
nate. Indeterminacy of the stable chan-
nel design problem has been addressed
in the following ways:
Using empirical relationships to
compute some of the unknowns
(e.g., meander parameters).
Assuming values for one or more of
the unknown variables.
Using structural controls to hold one
or more unknowns constant (e.g.,
controlling width with bank revet-
ments).
Ignoring some unknown variables by
simplifying the channel system. For
example, a single sediment size is
sometimes used to describe all
boundaries, and a single depth is
used to describe water depth rather
than mean and maximum depth as
suggested by Hey (1988).
Adopting additional governing equa-
tions based on assumed properties of
streams with movable beds and banks.
The design methods based on "ex-
tremal hypotheses" fall into this cate-
gory. These approaches are discussed
below under analytical approaches
for channels with moving beds.
Table 8.2 lists six examples of analytical
design procedures for sand-bed and
gravel channels. These procedures are
data-intensive and would be used in
high-risk or large-scale channel recon-
struction work.
Review Chapter
7's section on
hydraulic
geometry
relationships.
Stable Channel
Method
Copeland
Chang
Chang
Abou-Saida
and Saleh
White et al.
Griffiths
1994
1988
1988
1987
1981
1981
1 Domain
Sand-bed rivers
Sand-bed rivers
Gravel-bed rivers
Sand-bed canals
Sand-bed rivers
Gravel-bed rivers
1 Resistance
Equation
Brownlie
Various
Bray
Liu-Hwang
White et al.
Griffiths
1 Sediment
Transport Equation
Brownlie
Various
Chang (similar in
form to Parker,
Einstein)
Einstein-Brown
Ackers-White
Shields
entrainment
Third Relation
Left to designer's discretion
Minimum stream power
Minimum slope
Left to designer's discretion
Maximum sediment transport
Empirical stability index
Table 8.2: Selected
analytical procedures
for stable channel
design.
Stream Channel Restoration
8-37
-------
Figure 8.24: Low
energy system with
small bank angles.
Bank angles need to
be considered when
using the tractive
stress approach.
Tractive Stress (No Bed Movement)
Tractive stress or tractive force analysis
is based on the idea that by assuming
negligible bed material discharge
(Qs = 0) and a straight, prismatic chan-
nel with a specified cross-sectional
shape, the inequality in variables and
governing equations mentioned above
is eliminated. Details are provided in
many textbooks that deal with stable
channel design (e.g., Richards 1982, Si-
mons and Senturk 1977, French 1985).
Because the method is based on the
laws of physics, it is less empirical and
region-specific than regime or hydraulic
geometry formulas. To specify a value
for the force "required to initiate mo-
tion," the designer must resort to empir-
ical relationships between sediment size
and critical shear stress. In fact, the only
difference between the tractive stress ap-
proach for design stability analysis and
the allowable stress approach is that the
effect of cross-sectional shape (in partic-
ular, the bank angles) is considered in
the former (Figure 8.24). Effects of tur-
bulence and secondary currents are
poorly represented in this approach.
Tractive stress approaches typically pre-
sume constant discharge, zero bed ma-
terial sediment transport, and straight,
prismatic channels and are therefore
poorly suited for channels with moving
beds. Additional limitations of the trac-
tive stress design approach are discussed
by Brookes (1988) and USAGE (1994).
Tractive stress approaches are appropri-
ate for designing features made of rock
or gravel (artificial riffles, revetments,
etc.) that are expected to be immobile.
Channels with Moving Beds and
Known Slope
More general analytical approaches for
designing channels with bed material
discharge reduce the number of vari-
ables by assuming certain constant val-
ues (such as a trapezoidal
cross-sectional shape or bed sediment
size distribution) and by adding new
equations based on an extremal hy-
pothesis (Bettess and White 1987). For
example, in a refinement of the tractive
stress approach, Parker (1978) assumed
that a stable gravel channel is character-
ized by threshold conditions only at the
junction point between bed and banks.
Using this assumption and including
lateral diffusion of longitudinal mo-
mentum due to fluid turbulence in the
analysis, he showed that points on the
bank experience stresses less than
threshold while the bed moves.
Following Parker's work, Ikeda et al.
(1988) derived equations for stable
width and depth (given slope and bed
material gradation) of gravel channels
with unvegetated banks composed of
noncohesive material and flat beds in
motion at bankfull. Channels were as-
sumed to be nearly straight (sinuosity
< 1.2) with trapezoidal cross sections
free of alternate bars. In a subsequent
paper Ikeda and Izumi (1990) extended
the derivation to include effects of rigid
bank vegetation.
Extremal hypotheses state that a stable
channel will adopt dimensions that lead
to minimization or maximization of
some quantity subject to constraints im-
8-38
Chapter 8: Restoration Design
-------
posed by the two governing equations
(e.g., sediment transport and flow resis-
tance). Chang (1988) combined sedi-
ment transport and flow resistance
formulas with flow continuity and mini-
mization of stream power at each cross
section and through a reach to generate
a numerical model of flow and sedi-
ment transport. Special relationships for
flow and transverse sediment transport
in bends were also derived. The model
was used to make repeated computa-
tions of channel geometry with various
values for input variables. Results of the
analysis were used to construct a family
of design curves that yield d (bankfull
depth) and w (bankfull width), given
bankfull Q, S, and D5o. Separate sets of
curves are provided for sand and gravel
bed rivers. Regime-type formulas have
been fit to the curves, as shown in Table
8.3. These relationships should be used
with tractive stress analyses to develop
converging data that increase the de-
signer's confidence that the appropriate
channel dimensions have been selected.
Subsequent work by Thorne et al. (1988)
modified these formulas to account for
effects of bank vegetation along gravel-
bed rivers. The Thorne et al. (1988) for-
mulas in Table 8.3 are based on the data
presented by Hey and Thorne (1986) in
Table 7.6.
Channels with Moving Beds and
Known Sediment Concentration
White et al. (1982) present an analyti-
cal approach based on the Ackers and
White sediment transport function, a
companion flow resistance relationship,
and maximization of sediment trans-
port for a specified sediment concentra-
tion. Tables (White et al. 1981) are
available to assist users in implement-
ing this procedure. The tables contain
entries for sediment sizes from 0.06 to
100 millimeters, discharges up to
35,000 cubic feet per second, and sedi-
Table 8.3: Equa-
tions for river
width and depth.
Author I Year I Data
Chang
1988
Thorne
etal.
1988
Equiwidth point-bar
streams and stable canals
Straight braided streams
Braided point-bar and
wide-bend point-bar
streams; beyond upper limit
lie steep, braided streams
Same as for Thorne and Hey
1986
Adjustments for bank
vegetation3
Meandering or braided sand-bed rivers with:
0.00238 < SD50-°-5 Q-°-51 and 3.49k, *
SD50-° 5 Q-°-55 < 0.05
0.05 < SD50-°-5 Q-°-55 and
SD50-°-5 Q-°-51 < 0.047
0.047 < SD50-° 5
indefinite upper limit
Unknown and
unusual
33.2k,**
Gravel-bed rivers
Grassy banks with no trees w=1.46wc-
or shrubs 0.8317
1-5% tree and shrub cover w = 1.306 wc-
8.7307
5-50% tree and shrub cover
Greater than 50% tree and
shrub cover, or incised into
flood plain
w = 1.161 wc-
16.8307
w = 0.9656 wc-
10.6102
3.51k4*
0.93 1.0k4**
d = 0.8815dc +
0.2106
d = 0.5026 dc +
1.7553
d = 0.5413 dc +
2.7159
d = 0.7648 dc +
1.4554
0.47
0.45
1.905+ k,*** 0.47 0.2077 + k4*** 0.42
Chang equations for determining river width and depth. Coefficients for equations of the form w = kjQ1^; d = K4QK5; where w is mean bankfull width (ft), Q is the bankfull
or dominant discharge (ft3/s), d is mean bankfull depth (ft), D50 is median bed-material size (mm), and S is slope (ft/ft).
a wc and dc in these equations are calculated using exponents and coefficients from the row labeled "gravel-bed rivers".
= exp[-0.38(420.17SD50-°'5Q-°51 -1)°-4].
* = (S DM-°'5 )0-S4
* = 0.015-0.025 In Q-0.049 In (SD50-°-5).
**= 0.2490I ln(0.0010647D50'-15/SQ°-42)]2.
** = 0.2418 ln(0.0004419Dsol'l5/SQ°'42 ).
Stream Channel Restoration
8-39
-------
ment concentrations from 10 to 4,000
parts per million. However, this proce-
dure is not recommended for gravel bed
channels (USAGE 1994). Sediment con-
centration at bankfull flow is required
as an input variable, which limits the
usefulness of this procedure. Procedures
for computing sediment discharge, Qs,
are outlined in Chapter 7. Copeland
(1994) found that the White et al.
(1982) method for channel design was
not robust for cohesive bed materials,
artificial grade controls, and disequilib-
rium sediment transport. The method
was also found inappropriate for an un-
stable, high-energy ephemeral sand-bed
stream (Copeland 1994). However, Hey
(1990) found the Ackers-White sedi-
ment transport function performed well
when analyzing stability of 18 flood
control channels in Britain.
The approach described by Copeland
(1994) features use of the Brownlie
(1981) flow-resistance and sediment-
transport relations, in the form of the
software package "SAM" (Thomas et al.
1993). Additional features include the
determination of input bed material
concentration by computing sediment
concentration from hydraulic parame-
ters for an upstream "supply reach" rep-
resented by a bed slope, a trapezoidal
cross section, bed-material gradation,
and a discharge. Bank and bed rough-
ness are composited using the equal ve-
locity method (Chow 1959) to obtain
roughness for a cross section. A family
of slope-width solutions that satisfy the
flow resistance and sediment transport
relations are then computed. The de-
signer then selects any combination of
channel properties that are represented
by a point on the slope-width curve. Se-
lection may be based on minimum
stream power, maximum possible slope,
width constraint due to right-of-way, or
maximum allowable depth. The current
(1996) version of the Copeland proce-
dure assumes a straight channel with a
trapezoidal cross section and omits the
portion of the cross section above side
slopes when computing sediment dis-
charge. Effects of bank vegetation are
considered in the assigned roughness
coefficient.
The Copeland procedure was tested by
application to two existing stream chan-
nels, the Big and Colewa Creeks in
Louisiana and Rio Puerco in New Mex-
ico (Copeland 1994). Considerable pro-
fessional judgment was used in selection
of input parameters. The Copeland
method was found inapplicable to the
Big and Colewa Creeks (relatively stable
perennial streams with sand-clay beds),
but applicable to Rio Puerco (high-en-
ergy, ephemeral sand-bed stream with
stable profile and unstable banks). This
result is not surprising since all stable
channel design methods developed to
date presume alluvial (not cohesive or
bedrock) beds.
Use of Channel Models for
Design Verification
In general, a model can be envisioned
as a system by whose operation the
characteristics of other similar systems
may be predicted. This definition is
general and applies to both hydraulic
(physical) and computational (math-
ematical) models. The use and opera-
tion of computer models has improved
in recent years as a result of better
knowledge of fluvial hydraulics and the
development of sophisticated digital
control and data acquisition systems.
Any stream corridor restoration design
needs careful scrutiny because its long-
term impact on the stream system is not
easy to predict. Sound engineering
often dictates the use of computer mod-
els or physical models to check the va-
lidity of a proposed design. Since most
practitioners do not have easy access to
physical modeling facilities, computer
8-40
Chapter 8: Restoration Design
-------
models are much more widely used.
Computer models can be run in a qual-
itative mode with very little data or in a
highly precise quantitative mode with a
great deal of field data for calibration
and verification.
Computer models can be used to easily
and cheaply test the stability of a restora-
tion design for a range of conditions, or
for a variety of alternative channel con-
figurations. A "model" can vary in cost
from several hundred dollars to several
hundred thousand dollars, depending
on what model is used, the data input,
the degree of precision required, and the
length and complexity of the reach to be
modeled. The decision as to what mod-
els are appropriate should be made by a
hydraulic engineer with a background in
sediment transport.
The costs of modeling could be small
compared to the cost of redesign or re-
construction due to failure. If the conse-
quences of a project failure would result
in a high risk of catastrophic damage or
death, and the site-specific conditions
result in an unacceptable level of uncer-
tainty when applying computer models,
a physical model is the appropriate tool
to use for design.
Physical Models
In some instances, restoration designs
can become sufficiently complicated to
exceed the capabilities of available com-
putational models. In other situations,
time might be of the essence, thus pre-
cluding the development of new com-
putational modeling capabilities. In
such cases the designer must resort to
physical modeling for verification.
Depending on the scaling criteria used
to achieve similitude, physical models
can be classified as distorted, fixed, or
movable-bed models. The theory and
practice of physical modeling are cov-
ered in detail by French (1985), Jansen
et al. (1979), and Yalin (1971) and are
beyond the scope of this document.
Physical modeling, like computational
modeling, is a technology that requires
specialized expertise and considerable
experience. The U.S. Army Waterways
Experiment Station, Vicksburg, Missis-
sippi, has extensively developed the
technique of designing and applying
physical models of rivers.
Computer Models
Computer models are structured and
operated in the same way as a physical
model (Figure 8.25). One part of the
code defines the channel planform, the
bathymetry, and the material properties
of transported constituents. Other parts
of the code create conditions at the
boundaries, taking the place of the lim-
iting walls and flow controls in the
physical model. At the core of the com-
puter code are the water and sediment
transport solvers. "Turning on" these
solvers is equivalent to running the
physical model. At the end of the simu-
lation run the new channel bathymetry
and morphology are described by the
model output. This section summarizes
computational channel models that can
be useful for evaluation of stream corri-
dor restoration designs. Since it is not
possible to include every existing model
set up
model of
prototype
select model
to evaluate
design
execute
model
model
results
new
restoration
design
evaluate
results
accept
or revise
design
Figure 8.25: Use of
models for design
evaluation.
Modeling helps
evaluate economics
and effectiveness of
alternative designs.
Stream Channel Restoration
8-41
-------
Table 8.4: Examples of computational models.
CHARIMA I Fluvial-12 I HEC-6 I TABS-2 I Meander I USGS I D-OT I GSTARS
Discretization and formulation:
Unsteady flow | stepped hydrograph
One-dimensional | quasi-two-dimensional
Two-dimensional | depth-average flow
Deformable bed | banks
Graded sediment load
Nonuniform grid
Variable time stepping
Numerical solution scheme:
Standard step method
Finite difference
Finite element
Modeling capabilities:
Upstream water and sediment hydrographs
Downstream stage specification
Floodplain sedimentation
Suspended | total sediment transport
Bedload transport
Cohesive sediments
Bed armoring
Hydraulic sorting of substrate material
Fluvial erosion of streambanks
Bank mass failure under gravity
Straight | irregular nonprismatic reaches
Branched | looped channel network
Channel beds
Meandering belts
Rivers
Bridge crossings
Reservoirs
Y|Y
Y| N
N
Y|N
Y
Y
Y
Y|Y
Y| Y
N
Y|Y
Y
Y
N
N|Y
Y| N
N
Y|N
Y
Y
Y
Y|Y
N | N
Y
Y|N
Y
Y
IM
N|Y
N | N
Y
Y|N
Y
Y
N
Y|Y
N
Y| Y
Y|N
N
Y
N
N|Y
Y| Y
N
Y|Y
Y
Y
N
User support:
Model documentation
User guide | hot-line support
Y
Y
N
Y| N
Y
N
Y
Y
N
N
Y|N
Y| Y
N
N
Y
N
N
Y
Y
N
Y| N
Y
N
Y
Y
Y
N
Y|N
Y|N
Y
N
Y
N
Y
Y
Y
N
N | Y
Y
Y
Y
Y
N
N
Y| N
Y| N
N
N
Y
N
Y
Y
Y
Y
Y| N
IM
Y
N
N
N
N
Y|Y
Y|Y
Y
N
Y
Y
N
Y
Y
N
N | N
Y
N
N
N
N
N
N|N
N IN
Y
N
Y
N
N
Y
N
N
N | Y
N
Y
N
N
N
N
N|N
N|N
N
Y
Y
N
N
Y
N I N
Y
Yl N
Note: Y = Yes; N = No.
N | Y
Y|Y
N | Y
Y|Y
Y
Y
Y
d N
Y
N
Y
N
N
Y
Y
N
N
N
Y
N
Y
N
N
Y
N
Y
Y
N
Y
Y
N
Y
Y
N
N | Y
N
N
Y
Y
Y
Y
Y| Y
N|N
Y
N
Y
N
N
Y
Y
N
N | Y
Y
Y
Y
Y
Y
N
Y| Y
N | N
N
N
Y
N
Y
in the space available, the discussion
here is limited to a few selected models
(Table 8.4). In addition, Garcia et al.
(1994) review mathematical models of
meander bend migration.
These models are characterized as hav-
ing general applicability to a particular
class of problems and are generally
available for desktop computers using
DOS operating systems. Their concep-
tual and numerical schemes are robust,
having been proven in field applica-
tions, and the code can be successfully
used by persons without detailed
knowledge of the core computational
techniques. Examples of these models
and their features are summarized in
Table 8.4. The acronyms in the column
8-42
Chapter 8: Restoration Design
-------
titles identify the following models:
CHARIMA (Holly et al. 1990),
FLUVIAL-12 (Chang 1990), HEC-6,
TABS-2 (McAnally and Thomas 1985),
MEANDER (Johannesson and Parker
1985), the Nelson/Smith-89 model
(Nelson and Smith 1989), D-O-T
(Darby and Thorne 1996, Osman and
Thorne 1988), GSTARS (Molinas and
Yang 1996) and GSTARS 2.0 (Yang et al.
1998). GSTARS 2.0 is an enhanced
and improved PC version of GSTARS.
HEC-6, TABS-2, and USGS are federal,
public domain models, whereas
CHARIMA, FLUVIAL-12, MEANDER,
and D-O-T are academic, privately
owned models.
With the exception of MEANDER, all
the above models calculate at each
computational node the fractional sedi-
ment load and rate of bed aggradation
or degradation, and update the channel
topography. Some of them can simulate
armoring of the bed surface and hy-
draulic sorting (mixing) of the underly-
ing substrate material. CHARIMA,
FLUVIAL-12, HEC-6, and D-O-T can
simulate transport of sands and gravels.
TABS-2 can be applied to cohesive sedi-
ments (clays and silts) and sand sedi-
ments that are well mixed over the
water column. USGS is specially de-
signed for gravel bed-load transport.
FLUVIAL-12 and HEC-6 can be used for
reservoir sedimentation studies.
GSTARS 2.0 can simulate bank failure.
Comprehensive reviews on the capabili-
ties and performance of these and other
existing channel models are provided in
reports by the National Research Coun-
cil (1983), Fan (1988), Darby and
Thorne (1992), and Fan and Yen (1993).
Detailed Design
Channel Shape
Natural stream width varies continu-
ously in the longitudinal direction, and
depth, bed slope, and bed material size
vary continuously along the horizontal
plane. These variations give rise to nat-
ural heterogeneity and patterns of veloc-
ity and bed sediment size distribution
that are important to aquatic ecosystems.
Widths, depths, and slopes computed
during design should be adopted as
reach mean values, and restored chan-
nels should be constructed with asym-
metric cross sections (Hunt and Graham
1975, Keller 1978, Iversen et al. 1993,
MacBroom 1981) (Figure 8.26). Simi-
larly, meander planform should vary
from bend to bend about average values
of arc length and radius. A reconstructed
floodplain should not be perfectly flat
(Figure 8.27).
Channel Longitudinal Profile and
Riffle Spacing
In stream channels with significant
amounts of gravel (D50 > 3 mm) (Hig-
ginson and Johnston 1989), riffles
should be associated with steep zones
near meander inflection points. Riffles
are not found in channels with beds of
finer materials. Studies conducted by
Keller and Melhorn (1978) and con-
firmed by Hey and Thorne (1986) indi-
cate pool-riffle spacing should vary
between 3 and 10 channel widths and
average about 6 channel widths even in
bedrock channels. More recent work by
Roy and Abrahams (1980) and Higgin-
son and Johnston (1989) indicates that
pool-riffle spacing varies widely within
a given channel.
Average riffle spacing is often (but not
always) half the meander length since
riffles tend to occur at meander inflec-
tion points or crossovers. Riffles some-
times appear in groups or clusters. Hey
and Thorne (1986) analyzed data from
62 sites on gravel-bed rivers in the
United Kingdom and found riffle spac-
ing varied from 4 to 10 channel widths
Stream Channel Restoration
8-43
-------
Plan
Figure 8.26: Example
plan and profile of a
naturally meandering
stream. Channel cross
sections vary based
on width, depth, and
slope.
Station
with the least squares best fit at 6.31
channel widths. Riffle spacing tends to
be nearer 4 channel widths on steeper
gradients and 8 to 9 channel widths on
more gradual slopes (R.D. Hey, per-
sonal communication, 1997). Hey and
Thorne (1986) also developed regres-
sion formulas for riffle width, mean
depth, and maximum depth.
Stability Assessment
The risk of a restored channel being
damaged or destroyed by erosion or de-
position is an important consideration
for almost all restoration work. Design-
ers of restored streams are confronted
with rather high levels of uncertainty. In
some cases, it may be wise for designers
to compute risk of failure by calculating
the joint probability of design assump-
tions being false, design equation inac-
curacy, and occurrence of extreme
hydrologic events during project life.
Good design practice also requires
checking channel performance at dis-
charges well above and below the de-
sign condition. A number of
approaches are available for checking
both the vertical (bed) and horizontal
(bank) stability of a designed stream.
These stability checks are an important
part of the design process.
Vertical (Bed) Stability
Bed stability is generally a prerequisite
for bank stability. Aggrading channels
are liable to braid or exhibit accelerated
lateral migration in response to middle
or point bar growth. Degrading chan-
nels widen explosively when bank
heights and angles exceed a critical
threshold specific to bank soil type. Bed
aggradation can be addressed by stabi-
8-44
Chapter 8: Restoration Design
-------
lizing eroding channels upstream, con-
trolling erosion on the watershed, or in-
stalling sediment traps, ponds (Haan et
al. 1994), or debris basins (USAGE
1989b). If aggradation is primarily due
to deposition of fines, it can be ad-
dressed by narrowing the channel,
although a narrower channel might
require more bank stabilization.
If bed degradation is occurring or ex-
pected to occur, and if modification is
planned, the restoration initiative
should include flow modification,
grade control measures, or other ap-
proaches that reduce the energy gradi-
ent or the energy of flow. There are
many types of grade control structures.
The applicability of a particular type of
structure to a specific restoration de-
pends on a number of factors, such as
hydrologic conditions, sediment size
and loading, channel morphology,
floodplain and valley characteristics,
availability of construction materials,
ecological objectives, and time and
funding constraints. For more informa-
tion on various structure designs, refer
to Neilson et. al. (1991), which pro-
vides a comprehensive literature review
on grade control structures with an an-
notated bibliography. Grouted boulders
can be used as a grade control structure.
They are a key component in the suc-
cessful restoration of the South Platte
River corridor in Denver, Colorado
(McLaughlin Water Engineers, Ltd.,
1986).
Grade control structure stilling basins
can be valuable habitats in severely de-
graded warm water streams (Cooper
and Knight 1987, Shields and Hoover
1991). Newbury and Gaboury (1993)
describe the construction of artificial rif-
fles that serve as bed degradation con-
trols. Kern (1992) used "river bottom
ramps" to control bed degradation in a
River Danube meander restoration ini-
tiative. Ferguson (1991) reviews creative
designs for grade control structures that
improve streamside habitat and aes-
thetic resources (Figure 8.28).
Horizontal (Bank) Stability
Bank stabilization may be necessary in
restored channels due to floodplain
land uses or because constructed banks
are more prone to erosion than "sea-
soned" ones, but it is less than ideal if
ecosystem restoration is the objective.
Figure 8.27: A stream
meander and raised
floodplain. Natural
floodplains rise
slightly between a
crossover and an
apex of a meander.
Figure 8.28: Grade control structure. Control measures can
double as habitat restoration devices and aesthetic features.
Stream Channel Restoration
8-45
-------
Floodplain plant communities owe
their diversity to physical processes that
include erosion and deposition associ-
ated with lateral migration (Henderson
1986). Bank erosion control methods
must be selected with the dominant
erosion mechanisms in mind (Shields
and Aziz 1992).
Bank stabilization can generally be
grouped into one of the following
three categories: (1) indirect methods,
(2) surface armor, and (3) vegetative
methods. Armor is a protective material
in direct contact with the streambank.
Armor can be categorized as stone,
other self-adjusting armor (sacks,
blocks, rubble, etc.), rigid armor (con-
crete, soil cement, grouted riprap, etc.)
and flexible mattress (gabions, concrete
blocks, etc.). Indirect methods extend
into the stream channel and redirect the
flow so that hydraulic forces at the
channel boundary are reduced to a
nonerosive level. Indirect methods can
be classified as dikes (permeable and
impermeable) and other flow deflectors
such as bendway weirs, stream "barbs,"
and Iowa vanes. Vegetative methods can
function as either armor or indirect pro-
tection and in some applications can
function as both simultaneously. A
fourth category is composed of tech-
niques to correct problems caused by
geotechnical instabilities.
Guidance on selection and design of
bank protection measures is provided
by Hemphill and Bramley (1989) and
Henderson (1986). Coppin and
Richards (1990), USDA-NRCS (1996),
and Shields et al. (1995) provide addi-
tional detail on the use of vegetative
techniques (see following section).
Newly constructed channels are more
susceptible to bank erosion than older
existing channels, with similar inflows
and geometries, due to the influence of
vegetation, armoring, and the seasoning
effect of clay deposition on banks
(Chow 1959). In most cases, outer
banks of restored or newly constructed
meanders will require protection. Struc-
tural techniques are needed (e.g.,
Thome et al. 1995) if immediate stabil-
ity is required, but these may incorpo-
rate living components. If time permits,
the new channel may be constructed
"in the dry" and banks planted with
woody vegetation. After allowing the
vegetation several growing seasons to
develop, the stream may be diverted in
from the existing channel (R.D. Hey,
personal communication, 1997).
Bank Stability Check
Outer banks of meanders erode, but
erosion rates vary greatly from stream
to stream and bend to bend. Observa-
tion of the project stream and similar
reaches, combined with professional
judgment, may be used to determine
the need for bank protection, or ero-
sion may be estimated by simple rules
of thumb based largely on studies that
relate bend migration rates to bend
geometry (e.g., Apmann 1972 and re-
view by Odgaard 1987) (Figure 8.29).
More accurate prediction of the rate of
erosion of a given streambank is at or
beyond the current state of the art. No
standard methods exist, but several re-
cently developed tools are available.
None of these have been used in ex-
tremely diverse settings, and users
should view them with caution.
Tools for predicting bank erosion may
be divided into two groups: (1) those
which predict erosion primarily due to
the action of water on the streambank
surface and (2) those which focus on
subsurface geotechnical characteristics.
Among the former is an index of
streambank erodibility based on field
observations of emergency spillways
(Moore et al. 1994, Temple and Moore
1997). Erosion is predicted for sites
8-46
Chapter 8: Restoration Design
-------
Figure 8.29: Channel exhibiting accelerated
lateral migration. Erosion of an outer bank
on the Missouri River is a natural process;
however, the rate of erosion should be
monitored.
unreliable
unstable
stable
where a power number based on veloc-
ity, depth, and bend geometry exceeds
an credibility index computed from
tabulated values of streambank material
properties. Also among this group are
analytical models such as the one devel-
oped by Odgaard (1989), which con-
tain rather sophisticated representations
of flow fields, but require input of an
empirical constant to quantify soil and
vegetation properties. These models
should be applied with careful consid-
eration of their limitations. For exam-
ple, Odgaard's model should not be
applied to bends with "large curvature."
The second group of predictive tools fo-
cuses on banks that undergo mass fail-
ure due to geotechnical processes. Side
slopes of deep channels may be high
and steep enough to be geotechnically
unstable and to fail under the influence
of gravity. Fluvial processes in such a
situation serve primarily to remove
blocks of failed material from the bank
toe, leading to a resteepened bank pro-
file and a new cycle of failure, as shown
in Figure 8.30. Study of bank failure
processes along incised channels has
unreliable
unstable
tt
10° 45° 90°
Bank Angle (deg)
Stage II
10° 45° 90°
Bank Angle (deg)
Stage
Figure 8.30: Bank failure stages. Stability of
a bank will vary from stable to unstable
depending on bank height, bank angle, and
soil conditions.
Stream Channel Restoration
8-47
-------
led to a procedure for relating bank
geometry to stability for a given set of
soil conditions (Osman and Thorne
1988). If banks of a proposed design
channel are to be higher than about 10
feet, stability analysis should be con-
ducted. These analyses are described in
detail in Chapter 7. Bank height esti-
mates should allow for scour along the
outside of bends. High, steep banks are
also susceptible to internal erosion, or
piping, as well as streambanks of soils
with high dispersion rates.
Allowable Velocity Check
Fortier and Scobey (1926) published ta-
bles regarding the maximum nonscour-
ing velocity for given channel boundary
materials. Different versions of these ta-
bles have appeared in numerous subse-
quent documents, notably Simons and
Senturk (1977) and USAGE (1991). The
applicability of these tables is limited to
relatively straight silt and sand-bed
channels with depths of flow less than
3 feet and very low bed material loads.
Adjustments to velocities have been
suggested for situations departing from
those specified. Although slight refine-
ments have been made, these data still
form the basis of the allowable velocity
approach.
Figure 8.31 contains a series of graphs
that summarize the tables and aid in
selecting correction factors for flow
depth, sediment concentration, flow
frequency, channel curvature, bank
slope, and channel boundary soil
properties. Use of the allowable velo-
city approach is not recommended
for channels transporting a significant
load of material larger than 1 mm.
The restoration design, however,
should also consider the effects of
hydraulic roughness and the protec-
tion afforded by vegetation.
Perhaps because of its simplicity, the
allowable velocity method has been
used directly or in slightly modified
form for many restoration applications.
Miller et al. (1983) used allowable ve-
locity criteria to design man-made
gravel riffles located immediately down-
stream of a dam releasing a constant
discharge of sediment-free water.
Shields (1983) suggested using allow-
able velocity criteria to size individual
boulders placed in channels to serve as
instream habitat structures. Tarquin and
Baeder (1983) present a design ap-
proach based on allowable velocity for
low-order ephemeral streams in
Wyoming landscapes disturbed by sur-
face mining. Velocity of the design
event (10-year recurrence interval) was
manipulated by adjusting channel
length (and thus slope), width, and
roughness. Channel roughness was ad-
justed by adding meanders, planting
shrubs, and adding coarse bed material.
The channel width-to-depth ratio de-
sign was based on the pre-mining chan-
nel configuration.
Allowable Stress Check
Since boundary shear stress is more ap-
propriate than velocity as a measure of
the forces driving erosion, graphs have
also been developed for allowable shear
stress. The average boundary shear
stress acting on an open channel con-
veying a uniform flow of water is given
by the product of the unit weight of
water (y, lb/ft3) times the hydraulic ra-
dius (R, ft) times the bed slope S:
Figure 8.32 is an example of allowable
shear stress criteria presented in graphi-
cal form. The most famous graphical
presentation of allowable shear stress
criteria is the Shields diagram, which
depicts conditions necessary for initial
movement of noncohesive particles on
8-48
Chapter 8: Restoration Design
-------
ro
alignment
1.0
16 14 12 10 8 6 4
Curve Radius * Water Surface Width
3456789 10 o
Flood Frequency (percent chance) S 0.8
1.2
1.1
0.9
I 0.6
C
0)
t 0.4
bank slope
5 "' 1.5 2.0 2.5 3.0
Notes:
In no case should the
allowable velocity be
exceeded when the 10%
chance discharge occurs,
regardless of the design
flow frequency.
depth of design flow
4 6 8 10 12 14 16 18 20
Water Denth (feet)
0,1.2
& 1.1
U
c 1.0
1.5 2.0 2.5 3.0
Cotangent of Slope Angle (z)
0.9
O I V I £
Water Depth (feet)
> 0.8
density
\ e
38
Basic Velocities for Coherent Earth Materials (vb)
7.0
Racii
0.2 0.4 0.6 0.8 1.0 1.2 1.4
Void Ratio (e)
w
Basic Velocity for Discrete Particles of Earth Materials (vh)
.-, FineS Sand Gravel Cobble
3.5
sediment laden flow
Ts 20 22 24
10 12 14 16 . ^
Plasticity Index
5.5
5.0
£4.5
H-
.~ 4.0
u
_0
£ 3.5
u
OQ '
2.5
2.0
13.0
12.0
11.0
10.0
* 8.0
£7.0
f 6.0
u 5.0
| 4-°
3.0
2.0
1.0
0.0
Enter chart with D75 particle size
to determine basic velocity.
sediment laden
sediment free
_i I
Grain Size (inches)
2 4681015
Allowable Velocities for Unprotected Earth Channels
Channel Boundary Materials Allowable Velocity
10 12 14 16 18 20 22 24
Plasticity Index
Discrete Particles
Sediment Laden Flow
Dys > 0.4mm
Dy; < 0.4mm
Sediment Free Flow
Dys > 0.2mm
Dys < 0.2mm ^.u ipb
Coherent Earth Materials
PI > 10 basic velocity chart value xDxAxFxCe
Pl<10 2.0 fps
basic velocity chart value x D x A x B
2.0 fps
basic velocity chart value x D x A x B
2.0 fps
Figure 8.31: Allowable velocities for unprotected earth channels. Curves reflect practical experience in
design of stable earth channels.
Source: USDA Soil Conservation Service 1977.
Stream Channel Restoration
8-49
-------
Figure 8.32:
Allowable mean
shear stress for
channels with
boundaries of non-
cohesive material
larger than 5 mm
carrying negligible
bed material load.
Shear stress
diminishes with
increased suspend-
ed sediment con-
centrations.
Source: Lane 1955.
1.00
0.70
0.40
0.20
0.10
n
01
0.02
0.01
C = fine suspended sediment
concentration
C>20
i i i
0.1 0.2 0.3 0.5 0.7 1
D50 (mm)
345
a flat bed straight channel in terms of
dimensionless variables (Vanoni 1975).
The Shields curve and other allowable
shear stress criteria (e.g., Figure 10.5,
Henderson 1966; Figure 7.7, Simons
and Senturk 1977) are based on labora-
tory and field data. In simplest form,
the Shields criterion for channel stabil-
ity is (Henderson 1966):
RS/[(SS-1)DJ < a constant
for Ds > ~ 6 mm
where Ss is the specific gravity of the
sediment and DS is a characteristic bed
sediment size, usually taken as the me-
dian size, D50, for widely graded mater-
ial. Note that the hydraulic radius, R,
and the characteristic bed sediment size,
DS, must be in the same units for the
Shields constant to be dimensionless.
The dimensionless constant is based on
measurements and varies from 0.03 to
0.06 depending on the data set used to
determine it and the judgment of the
user (USAGE 1994).
These constant values are for straight
channels with flat beds (no dunes or
other bedforms). In natural streams,
bedforms are usually present, and val-
ues of this dimensionless constant re-
quired to cause entrainment of bed
material may be greater than 0.06. It
should be noted that entrainment does
not imply channel erosion. Erosion will
occur only if the supply of sediment
from upstream is less than that trans-
ported away from the bed by the flow.
However, based on a study of 24 gravel-
bed rivers in the Rocky Mountain re-
gion of Colorado, Andrews (1984)
concluded that stable gravel-bed chan-
nels cannot be maintained at values of
the Shields constant greater than about
0.080. Smaller Shields constant values
are more conservative with regard to
channel scour, but less conservative
with regard to deposition. If Ss = 2.65,
and the constant is assumed to be 0.06,
the equation above simplifies to D50 =
10. IRS.
Allowable shear stress criteria are not
very useful for design of channels with
beds dominated by sand or finer mate-
rials. Sand beds are generally in motion
at design discharge and have dunes, and
their shear stress values are much larger
than those indicated by the Shields cri-
terion, which is for incipient motion on
a plane bed. Allowable shear stress data
for cohesive materials show more scat-
ter than those for sands and gravels
(Grissinger et al. 1981, Raudkivi and
Tan 1984), and experience and observa-
tion with local channels are preferred to
published charts like those shown in
Chow (1959). Models of cohesive soil
erosion require field or laboratory eval-
uation of model parameters or con-
stants. Extrapolation of laboratory
flume results to field conditions is diffi-
cult, and even field tests are subject to
site-specific influences. Erosivity of co-
hesive soils is affected by the chemical
composition of the soil, the soil water,
and the stream, among other factors.
However, regional shear stress criteria
may be developed from observations of
channels with sand and clay beds. For
example, USAGE (1993) determined
that reaches in the Coldwater River Wa-
8-50
Chapter 8: Restoration Design
-------
tershed in northwest Mississippi should
be stable with an average boundary
shear stress at channel-forming (2-year)
discharge of 0.4 to 0.9 lb/ft2.
The value of the Shields constant also
varies with bed material size distribu-
tion, particularly for paved or armored
beds. Andrews (1983) derived a regres-
sion relationship that can be expressed
as:
RS/[(SS-1)DJ< 0.0834 (DJDJ
When the left side of the above expres-
sion equals the right, bed-sediment par-
ticles of size D. are at the threshold of
motion. The D50 value in the above ex-
pression is the median size of subsur-
face material. Therefore, if D50 = 30 mm,
particles with a diameter of 100 mm
will be entrained when the left side of
the above equation exceeds 0.029. This
equation is for self-formed rivers that
have naturally sorted gravel and cobble
bed material. The equation holds for
values of D./D5o between 0.3 and 4.2. It
should be noted that R and D on the
i
left side of the above equation must be
expressed in the same units.
Practical Guidance: Allowable
Velocity and Shear Stress
Practical guidance for application of
allowable velocity and shear stress
approaches is provided by the Natural
Resources Conservation Service (USDA-
NRCS), formerly the U.S. Soil Conser-
vation Service (SCS)(1977), and USAGE
(1994). See Figure 8.31.
Since form roughness due to sand
dunes, vegetation, woody debris, and
large geologic features in streams dissi-
pates energy, allowable shear stress for
bed stability may be higher than indi-
cated by laboratory flume data or data
from uniform channels. It is important
to compute cross-sectional average ve-
locities or shear stresses over a range of
discharges and for seasonal changes in
the erosion resistance of bank materials,
rather than for a single design condition.
Frequency and duration of discharges
causing erosion are important factors in
stability determination. In cobble- or
boulder-bed streams, bed movement
sometimes occurs only for discharges
with return periods of several years.
Computing velocity or shear stress from
discharge requires design cross sections,
slope, and flow resistance data. If the
design channel is not extremely uni-
form, typical or average conditions for
rather short channel reaches should be
considered. In channels with bends,
variations in shear stress across the sec-
tion can lead to scour and deposition
even when average shear stress values
are within allowable limits. The NRCS
(formerly SCS) (1977) gives adjustment
factors for channel curvature in graphi-
cal form that are based on very limited
data (see Figure 8.31). Velocity distribu-
tions and stage-discharge relations for
compound channels are complex
(Williams and Julien 1989, Myers and
Lyness 1994).
Allowable velocity or shear stress crite-
ria should be applied to in-channel
flow for a compound cross section with
overbank flow, not cross-sectional aver-
age conditions (USAGE 1994). Channel
flow resistance predictors that allow for
changing conditions with changing dis-
charge and stage should be used rather
than constant resistance values.
If the existing channel is stable, design
channel slope, cross section, and rough-
ness may be adjusted so that the current
and proposed systems have matching
curves of velocity versus discharge
(USAGE 1994). This approach, while
based on allowable velocity concepts,
releases the procedure from published
empirical values collected in other
rivers that might be intrinsically differ-
ent from the one in question.
Stream Channel Restoration
8-51
-------
Figure 8.33:
Brookes' stream
power stability
criteria. Stream
power is the prod-
uct of bankfull
velocity and shear
stress.
Allowable Stream Power or
Slope
Brookes (1990) suggested the product
of bankfull velocity and shear stress,
which is equal to the stream power per
unit bed area, as a criterion for stability
in stream restoration initiatives. This is
based on experience with several
restoration initiatives in Denmark and
the United Kingdom with sandy banks,
beds of glacial outwash sands, and a
rather limited range of bankfull dis-
charges (~15 to 70 cfs). These data are
plotted as squares, triangles, and circles
in Figure 8.33.
Brookes suggested that a stream power
value of 2.4 ft-lb/sec/ft2 discriminated
well between stable and unstable chan-
nels. Projects with stream powers less
than about 1.0 ft-lb/sec/ft2 failed
through deposition, whereas those with
stream powers greater than about 3.4 ft-
lb/sec/ft2 failed through erosion.
Since these criteria are based on obser-
vation of a limited number of sites, ap-
plication to different stream types (e.g.,
cobble-bed rivers) should be avoided.
0.1
However, similar criteria may be devel-
oped for basins of interest. For example,
data points representing stable reaches
in the Coldwater River watershed of
northwestern Mississippi are shown in
Figure 8.34 as stars. This watershed is
characterized by incised, straight (chan-
nelized) sand-bed channels with cohe-
sive banks. Slopes for stable reaches
were measured in the field, and 2-year
discharges were computed using a wa-
tershed model (HEC-1) (USAGE 1993).
Brookes' stream power criterion is one of
several region-specific stability tests. Oth-
ers include criteria based on slope and
shear stress. Using empirical data and
observation, the Corps of Engineers has
developed relationships between slope
and drainage area for various watersheds
in northwestern Mississippi (USAGE
1989c). For example, stable reaches in
three watersheds had slopes that clus-
tered around the regression line:
S = 0.0041 A'0365
where A is the contributing drainage
area in square miles. Reaches with much
steeper slopes tended to be degra-
0.01
HI
Q.
_0
l/l
c
c
(0
u
0.001
0.0001
o
failure through erosion
generally successful
failure through deposition
lines of constant stream power
stable reaches, Coldwater
River basin, Mississippi
-
10
100
Bankfull Discharge per Unit Width, ft2 s'1
8-52
Chapter 8: Restoration Design
-------
Allowable Shear Stress
The shape of the bed material size distribution is an
important parameter for determining the threshold
of motion of individual sediment sizes in a bed con-
taining a mixture of sand and gravel. Beds com-
posed of unimodal (particle-size distribution shows
no secondary maxima) mixtures of sand and gravel
were found to have a narrow range of threshold
shear stresses for all sizes present on the bed sur-
face. For unimodal beds, the threshold of motion of
all grain sizes on the bed was found to be estimated
adequately by using the Shields curve for the medi-
an grain size. Bed sediments composed of bimodal
(particle-size distribution shows one secondary maxi-
mum) mixtures of sands and gravels were found to
have threshold shear stresses that are still a function
of grain size, although much less so than predicted
by the Shields curve. For bed material with bimodal
size distributions, using the Shields curve on individ-
ual grain sizes greater than the median size overesti-
mates the threshold of motion and underestimates
the threshold of motion for grain sizes less than the
median size. Critical shear stresses for gravel beds
may be elevated if gravels are tightly interlocked or
imbedded.
Jackson and Van Haveren (1984) present an itera-
tive technique for designing a restored channel
based on allowable shear stress. Separate calcula-
tions were performed for channel bed and banks.
Channel design included provision for gradual
channel narrowing as the bank vegetation devel-
ops, and bank cohesion and resistance to erosion
increase. Newbury and Gaboury (1993) use an
allowable tractive force graph from Lane (1955) to
check stability of channel restoration initiatives in
Manitoba streams with cobble and gravel beds.
Brookes (1991) gives an example of the application
of this method for designing urban channels near
London. From a practical standpoint, boundary
shear stresses can be more difficult to measure and
conceptualize than velocities (Brookes 1995).
Allowable shear stress criteria may be converted to
allowable velocities by including mean depth as a
parameter.
The computed shear stress values are averages for
the reach in question. Average values are exceeded
at points, for example, on the outside of a bend.
dational, while those with more gradual
slopes tended to be aggradational.
Downs (1995) developed stability crite-
ria for channel reaches in the Thames
Basin of the United Kingdom based
entirely on slope: channels straightened
during the 20th century were deposi-
tional if slopes were less than 0.005 and
erosional if slopes were greater.
Sediment Yield and Delivery
Sediment Transport
If a channel is designed using an empiri-
cal or a tractive stress approach, compu-
tation of sediment-transport capacity
allows a rough check to determine
whether deposition is likely to be a
problem. Sediment transport relation-
ships are heavily dependent on the data
used in their development. Inaccuracy
may be reduced by selecting transport
functions appropriate to the stream type
and bed sediment size in question. Addi-
tional confidence can be achieved by ob-
taining calibration data; however,
calibration data are not available from a
channel yet to be constructed. If the ex-
isting channel is reasonably stable, de-
signers can compute a sediment
discharge versus streamflow relationship
for the existing and proposed design
channels using the same sediment trans-
port function and try to match the curves
as closely as possible (USAGE 1994).
Stream Channel Restoration
8-53
-------
If information is available regarding
sediment inflows into the new channel,
a multiyear sediment budget can be
computed to project likely erosion and
deposition and possible maintenance
needs. Sediment load can also be com-
puted, using the hydraulic properties
and bed material gradations of the up-
stream supply reach and a suitable sedi-
ment transport function. The USAGE
software SAM (Copeland 1994) in-
cludes routines that compute hydraulic
properties for uniform flow and sedi-
ment discharge for single cross sections
of straight channels using any of 13 dif-
ferent sediment transport functions.
Cross sections may have complex geom-
etry and boundary materials that vary
along the section. Output can be com-
bined with a hydrograph or a flow du-
ration curve to obtain sediment load.
HEC-6 (USAGE 1993) is a one-
dimensional movable-boundary,
open-channel-flow numerical model
designed to simulate and predict
changes in river profiles resulting from
scour and deposition over moderate
time periods, typically years, although
applications to single flood events are
possible. A continuous discharge record
is partitioned into a series of steady
flows of variable discharge and dura-
tion. For each discharge, a water surface
profile is calculated, providing energy
slope, velocity, depth, and other vari-
ables at each cross section. Potential
sediment transport rates are then com-
puted at each section. These rates,
combined with the duration of the flow,
permit a volumetric accounting of sedi-
ment within each reach. The amount of
scour or deposition at each section is
then computed, and the cross section
geometry is adjusted for the changing
sediment volume. Computations then
proceed to the next flow in the sequence,
and the cycle is repeated using the up-
dated cross section geometry. Sediment
calculations are performed by grain size
fractions, allowing the simulation of
hydraulic sorting and armoring.
HEC-6 allows the designer to estimate
long-term response of the channel to a
predicted series of water and sediment
supply. The primary limitation is that
HEC-6 is one-dimensional, i.e., geome-
try is adjusted only in the vertical direc-
tion. Changes in channel width or
planform cannot be simulated. Another
Federal sediment routing model is the
GSTARS 2.0 (Yang et al. 1998). GSTARS
2.0 can be used for a combination of
subcritical and supercritical flow com-
putations without interruption in a
semi-two-dimensional manner. The use
of stream tube concept in sediment
routing enables GSTARS 2.0 to simulate
channel geometry changes in a semi-
three-dimensional manner.
The amount and type of sediment sup-
plied to a stream channel is an impor-
tant consideration in restoration
because sediment is part of the balance
(i.e., between energy and material load)
that determines channel stability. A gen-
eral lack of sediment relative to the
amount of stream power, shear stress,
or energy in the flow (indexes of trans-
port capacity) usually results in erosion
of sediment from the channel boundary
of an alluvial channel. Conversely, an
oversupply of sediment relative to the
transport capacity of the flow usually
results in deposition of sediment in
that reach of stream.
Bed material sediment transport analy-
ses are necessary whenever a restoration
initiative involves reconstructing a
length of stream exceeding two mean-
der wavelengths. A reconstruction that
modifies the size of a cross section and
the sinuosity for such a length of chan-
nel should be analyzed to ensure that
upstream sediment loads can be trans-
ported through the reconstructed reach
with minimal deposition or erosion.
Different storm events and the average
8-54
Chapter 8: Restoration Design
-------
annual transported bed material load
also should be examined.
Sediment Discharge Functions
The selection of an appropriate dis-
charge formula is an important consid-
eration when attempting to predict
sediment discharge in streams. Numer-
ous sediment discharge formulas have
been proposed, and extensive sum-
maries are provided by Alonso and
Combs (1980), Brownlie (1981), Yang
(1996), Bathurst (1985), Gomez and
Church (1989), and Parker (1990).
Sediment discharge rates depend on
flow velocity; energy slope; water
temperature; size, gradation, specific
gravity, and shape of the bed material
and suspended-sediment particles;
channel geometry and pattern; extent of
bed surface covered by coarse material;
rate of supply of fine material; and bed
configuration. Large-scale variables such
as hydrologic, geologic, and climatic
conditions also affect the rate of sedi-
ment transport. Because of the range
and number of variables, it is not possi-
ble to select a sediment transport for-
mula that satisfactorily encompasses all
the conditions that might be encoun-
tered. A specific formula might be more
accurate than others when applied to
a particular river, but it might not be
accurate for other rivers.
Selection of a sediment transport for-
mula should include the following
considerations (modified from Yang 1996):
Type of field data available or mea-
surable within time, budget, and
work hour limitations.
Independent variables that can be
determined from available data.
Limitations of formulas versus field
conditions.
If more than one formula can be used,
the rate of sediment discharge should
be calculated using each formula. The
formulas that best agree with available
measured sediment discharges should
be used to estimate the rate of sediment
discharge during flow conditions when
actual measurements are not available.
The following formulas may be consid-
ered in the absence of any measured
sediment discharges for comparison:
Meyer-Peter and Muller (1948)
formula when the bed material is
coarser than 5 mm.
Einstein (1950) formula when bed
load is a substantial part of the total
sediment discharge.
Toffaleti (1968) formula for large
sand-bed rivers.
Colby (1964) formula for rivers with
depths less than 10 feet and median
bed material values less than 0.8 mm.
Yang (1973) formula for fine to
coarse sand-bed rivers.
Yang (1984) formula for gravel trans-
port when most of the bed material
ranges from 2 to 10 mm.
Ackers and White (1973) or
Engelund and Hansen (1967) formu-
la for sand-bed streams having sub-
critical flow.
Laursen (1958) formula for shallow
rivers with fine sand or coarse silt.
Available sediment data from a gaging
station may be used to develop an em-
pirical sediment discharge curve in the
absence of a satisfactory sediment dis-
charge formula, or to verify the sedi-
ment discharge trend from a selected
formula. Measured sediment discharge
or concentration should be plotted
against streamflow, velocity, slope,
depth, shear stress, stream power, or
unit stream power. The curve with the
least scatter and systematic deviation
should be selected as the sediment rat-
ing curve for the station.
Stream Channel Restoration
8-55
-------
Sediment Budgets
A sediment budget is an accounting of
sediment production in a watershed.
It attempts to quantify processes of ero-
sion, deposition, and transport in the
basin. The quantities of erosion from all
sources in a watershed are estimated
using various procedures. Typically, the
tons of erosion from the various sources
are multiplied by sediment delivery ra-
tios to estimate how much of the
eroded soil actually enters a stream.
The sediment delivered to the streams
is then routed through the watershed.
The sediment routing procedure in-
volves estimating how much of the sed-
iment in the stream ends up being
deposited in lakes, reservoirs, wetlands,
or floodplains or in the stream itself.
An analysis of the soil textures by ero-
sion process is used to convert the tons
of sediment delivered to the stream into
tons of silt and clay, sand, and gravel.
Sediment transport processes are ap-
plied to help make decisions during the
sediment routing analysis. The end re-
sult is the sediment yield at the mouth
of the watershed or the beginning of a
project reach.
Table 8.5 is a summary sediment budget
for a watershed. Note that the informa-
tion in the table may be from measured
values, from estimates based on data
from similar watersheds, or from model
outputs (AGNPS, SWRRBWQ, SWAT,
WEPP, RUSLE, and others. Contact the
NRCS National Water and Climate Data
Center for more information on these
models). Sediment delivery ratios are
determined for watershed drainage
areas, based on sediment gauge data
and reservoir sedimentation surveys.
The watershed is subdivided into sub-
watersheds at points where significant
sediment deposition occurs, such as at
bridge or road fills; where stream cross-
ings cause channel and floodplain
constrictions; and at reservoirs, lakes,
significant flooded areas, etc. Sediment
budgets similar to the table are con-
structed for each subwatershed so the
sediment yield to the point of deposi-
tion can be quantified.
A sediment budget has many uses, in-
cluding identification of sediment
sources for treatment (Figure 8.34). If
the goal for a restoration initiative is to
reduce sedimentation from a watershed,
it is critical to know what type of ero-
sion is producing the most sediment
and where that erosion is occurring. In
stream corridor restoration, sediment
yield (both in terms of quantity and
average grain size diameter) to a stream
and its floodplain need to be identified
and considered in designs. In channel
stability investigations, the amount of
sand and gravel sediment entering the
stream from the watershed needs to be
quantified to refine bed material trans-
port calculations.
Example of a Sediment Budget
A simple application of a sediment
transport equation in a field situation
illustrates the use of a sediment budget.
Figure 8.35 shows a stream reach being
evaluated for stability prior to develop-
ing a stream corridor restoration plan.
Five representative channel cross sec-
tions (A, B, C, D, and E) are surveyed.
Locations of the cross sections are se-
lected to represent the reach above
and below the points where tributary
streams, D and E, enter the reach. Addi-
tional cross sections would need to be
surveyed if the stream at A, B, C, D,
or E is not typical of the reach.
An appropriate sediment transport
equation is selected, and the transport
capacity at each cross section for bed
material is computed for the same flow
conditions. Figure 8.35 shows the sedi-
ment loads in the stream and the trans-
port capacities at each point.
8-56
Chapter 8: Restoration Design
-------
Table 8.5: Example of a sediment budget for a watershed.
Protection I Erosion
Level I Source
Acres I Average
Annual I Sediment I Sediment I Sediment
Sediment Delivered
Adequate
Inadequate
Adequate
Inadequate
Adequate
Inadequate
Adequate
Inadequate
Adequate
Inadequate
or I Erosion Rate Erosion I Delivery
Miles I (tons/acre/year (tons/ I Ratio
I or tons/bank year) I (percent)
I mile/year)
Deposited I to Blue Stem Lake
Sheet, rill, and
ephemeral gully
Cropland
Cropland
Pasture/hayland
Pasture/hayland
Forestland
Forestland
Parkland
Parkland
Other
Other
Classic gully
Streambank
Slight 14
Moderate 10.5
Severe 3.5
6000
1500
3400
600
1200
300
700
0
420
0
N/A
3.0
6.5
1.0
6.0
0.5
5.5
1.0
0
2.0
0
N/A
18,000
9750
3400
3600
600
1650
700
0
840
0
600
50
150
600
Total erosic
100
1580
2100
30
30
20
20
20
20
30
30
20
20
700
100
100
Streams I Uplands & I I
I Floodplains I (tons/ I (percent)
I (tons/year) I year)
5400
2930
680
720
120
330
210
0
170
0
5400
1580
2100
14,380
7790
2940
3120
520
1430
560
0
730
0
| 440
3620
1960
460
480
80
220
140
0
110
0
160
140
320
420
560
1260
1680
10,730
33.7
18.3
4.3
4.5
0.7
2.1
1.3
0.0
1.0
0.0
5.2
11.7
15.7
The transport capacities at each point
are compared to the sediment load at
each point. If the bed material load ex-
ceeds the transport capacity, deposition
is indicated. If the bed material trans-
port capacity exceeds the coarse sedi-
ment load available, erosion of the
channel bed or banks is indicated.
Figure 8.35 compares the loads and
transport capacities within the reach.
The stream might not be stable below
B due to deposition. The 50 tons/day
deposition is less than 10 percent of the
total bed material load in the stream.
This small amount of sediment is prob-
ably within the area of uncertainty in
such analyses. The stream below C
probably is unstable due to the excess
energy (transport capacity) causing ei-
ther the banks or bottom to be eroded.
After this type of analysis is complete,
the stream should be inspected for
Figure 8.34: Eroded upland area. Upland
sediment sources should be identified in
a sediment budget.
Stream Channel Restoration
8-57
-------
Figure 8.35:
Sediment budget.
Stream reaches
should be evaluated
for stability prior
to developing a
restoration plan.
tributary D
Bed Material Load Routing Computations
Bed material load transport capacity at A
Bed material load transport capacity at B
Bed material load transport capacity at C
Bed material load transport capacity at D
Bed material load transport capacity at E
400 tons/day
BOO tons/day
900 tons/day
150 tons/day
250 tons/day
Transport capacity at A
Load to B
Transport capacity at B
400 tons
400 tons transported below A
+ 150 tons from tributary D
550 tons to B
500 tons
) tons deposition below B (550 - 500 = 50)
Load to C
500 tons transported below B
+ 250 tons from tributary E
750 tons to C
Transport capacity at C 900 tons
150 tons erosion below C (750 - 900 = -150 tons)
Note:
Numbers represent
tons/day bed material
load in stream.
areas where sediment is building up or
where the stream is eroding. If these
problem areas do not match the predic-
tions from the calculations, the sedi-
ment transport equation may be
inappropriate, or the sediment budget,
the hydrology, or the channel surveys
may be inaccurate.
Single Storm versus Average Annual
Sediment Discharge
The proceeding example predicts the
amount of erosion and deposition that
can be expected to occur over one day
at one discharge. The bed material
transport equation probably used one
grain size of sediment. In reality, a vari-
ety of flows over varying lengths of time
move a variety of sediment particle
sizes. Two other approaches should be
used to help predict the quantity of bed
material sediment transported by a
stream during a single storm event or
over a typical runoff year.
To calculate the amount of sediment
transported by a stream during a single
storm event, the hydrograph for the
event is divided into equal-length seg-
ments of time. The peak flow or the
average discharge for each segment is
determined. A spreadsheet can be devel-
oped that lists the discharges for each
segment of a hydrograph in a column
(Table 8.6). The transport capacity from
the sediment rating curve for each dis-
charge is shown in another column
(Figure 8.36). Since the transport ca-
pacity is in tons/day, a third column
should include the length of time repre-
sented by each segment of the hydro-
8-58
Chapter 8: Restoration Design
-------
Table 8.6: Sediment discharges for segments
of a hydrograph. The amount of sediment
discharged through a reach varies with time
during a stream flow event.
I Column 1
Column 2
I Column 3
1 Column 4
600
500
£400
o>
?300
(D
.E
1 Column 5 K
-------
graph. This column is multiplied by
the transport capacity to create a final
column that represents the amount of
sediment that could be transported over
each segment of the hydrograph. Sum-
ming the values in the last column
shows the total bed material transport
capacity generated by that storm.
Average annual sediment transport in
a stream can be determined using a
procedure very similar to the storm
prediction. The sediment rating curve
can be developed from predictive equa-
tions or from physical measurements.
The annual flow duration curve is sub-
stituted for the segmented hydrograph.
The same type of spreadsheet described
above can be used, and the sum of the
values in the last column is the annual
sediment-transport capacity (based on
predictive equations) or the actual an-
nual sediment transport if the rating
curve is based on measured data.
Sediment Discharge After Restoration
After the sediment transport analysis
results have been field-checked to en-
sure that field conditions are accurately
predicted, the same analyses are re-
peated for the new cross sections and
slope in a reconstructed stream or
stream reach. Plans and designs may be
modified if the second analysis indi-
cates significant deposition or erosion
could occur in the modified reach. If
potential changes in runoff or sedi-
ment yield are predicted to occur in the
watershed above a potential restoration
site, the sediment transport analyses
should be done again based on these
potential changes.
Stability Controls
The risk of a restored channel's being
damaged or destroyed by erosion or
deposition can be reduced if economic
considerations permit installation of
control measures. Control measures
are also required if "natural" levels
of channel instability (e.g., meander
migration) are unacceptable in the
restored reach.
In many cases, control measures double
as habitat restoration devices or aesthetic
features (Nunnally and Shields 1985,
Newbury and Gaboury 1993). Control
measures may be categorized as bed sta-
bilization devices, bank stabilization de-
vices, and hydrologic measures. Reviews
of control measures are found in Vanoni
(1975), Simons and Senturk (1977),
Petersen (1986), Chang (1988), and
USAGE (1989b, 1994), and are treated
only briefly here. Haan et al. (1994) pro-
vide design guidance for sediment con-
trol on small watersheds. In all cases,
sediment control systems should be
planned and designed with the geomor-
phic evolution of the watershed in mind.
8-60
Chapter 8: Restoration Design
-------
8.F Streambank Restoration
Even where streams retain relatively
natural patterns of flow and flooding,
stream corridor restoration might re-
quire that streambanks be temporarily
(years to decades) stabilized while
floodplain vegetation recovers. The ob-
jective in such instances is to arrest the
accelerated erosion often associated
with unvegetated banks, and to reduce
erosion to rates appropriate for the
stream system and setting. In these situ-
ations, the initial bank protection may
be provided primarily with vegetation,
wood, and rock as necessary (refer to
Appendix A).
In other cases, land development or
modified flows may dictate the use of
hard structures to ensure permanent
stream stability, and vegetation is used
primarily to address specific ecological
deficiencies such as a lack of channel
shading. In either case (permanent or
temporary bank stabilization), stream-
flow projections are used (as described
in Chapter 7) to determine the degree
to which vegetation must be supple-
mented with more resistant materials
(natural fabrics, wood, rock, etc.) to
achieve adequate stabilization.
The causes of excessive erosion may be
reversible through changes in land use,
livestock management, floodplain
restoration, or water management. In
some cases, even normal rates of bank
erosion and channel movement might
be considered unacceptable due to adja-
cent development, and vegetation
might be used primarily to recover
some habitat functions in the vicinity
of "hard" bank stabilization measures.
In either case, the considerations dis-
cussed above with respect to soils, use
of native plant species, etc., are applica-
ble within the bank zone. However, a
set of specialized techniques can be em-
ployed to help ensure plant establish-
ment and improve habitat conditions.
As discussed earlier in this chapter, inte-
gration of woody vegetative cuttings, in-
dependently or in combination with
other natural materials, in streambank
erosion control projects is generally re-
ferred to as soil bioengineering. Soil-
bioengineered bank stabilization
systems have not been standardized for
general application under particular
flow conditions, and the decision as to
whether and how to use them requires
careful consideration of a variety of fac-
tors. On larger streams or where erosion
is severe, an effective approach involves
a team effort that includes expertise in
soils, biology, plant sciences, landscape
architecture, geology, engineering, and
hydrology.
Soil bioengineering approaches usually
employ plant materials in the form of
live woody cuttings or poles of readily
sprouting species, which are inserted
deep into the bank or anchored in vari-
ous other ways. This serves the dual
purposes of resisting washout of plants
during the early establishment period,
while providing some immediate ero-
sion protection due to the physical re-
sistance of the stems. Plant materials
alone are sufficient on some streams
or some bank zones, but as erosive
forces increase, they can be combined
with other materials such as rocks, logs
or brush, and natural fabrics (Figure
8.37). In some cases, woody debris is
incorporated specifically to improve
habitat characteristics of the bank and
near-bank channel zones.
Preliminary site investigations (see
Figure 8.38) and engineering analyses
must be completed, as described in
Chapter 7, to determine the mode of
bank failure and the feasibility of using
Streambank Restoration
8-61
-------
vegetation as a component of bank sta-
bilization work. In addition to the tech-
nical analyses of flows and soils,
preliminary investigations must include
consideration of access, maintenance,
urgency, and availability of materials.
Generalizations regarding water levels
and flow velocities should be taken
only as indications of the experiences
reported from various bank stabiliza-
tion projects. Any particular site must
Figure 8.37: A stabilized streambank. Plant
materials can be combined with other materi-
als such as rocks, logs or brush, and natural
fabrics, [(a) during and (b) after.]
be evaluated to determine how vegeta-
tion can or cannot be used. Soil cohe-
siveness, the presence of gravel lenses,
ice accumulation patterns, the amount
of sunlight reaching the bank, and the
ability to ensure that grazing will be
precluded are all considerations in as-
sessing the suitability of vegetation to
achieve bank stabilization. In addition,
modified flow patterns may make por-
tions of the bank inhospitable to plants
because of inappropriate timing of in-
undation rather than flow velocities
and durations (Klimas 1987). The need
to extend protection well beyond the
immediate focus of erosion and to pro-
tect against flanking is an important
design consideration.
As noted in Section 8.E, streambank sta-
bilization techniques can generally be
classified as armor, indirect methods, or
vegetative methods. The selection of the
appropriate stabilization technique is ex-
tremely important and can be expressed
in terms of the factors discussed below.
Effectiveness of Technique
The inherent factors in the properties
of a given bank stabilization technique,
and in the physical characteristics of a
proposed work site, influence the suit-
ability of that technique for that site.
Effectiveness refers to the suitability
and adequacy of the technique. Many
techniques can be designed to ade-
quately solve a specific bank stability
problem by resisting erosive forces and
geotechnical failure. The challenge is
to recognize which technique matches
the strength of protection against the
strength of attack and therefore per-
forms most efficiently when tested by
the strongest process of erosion and
most critical mechanism of failure. En-
vironmental and economic factors are
integrated into the selection procedure,
generally making soil bioengineering
methods very attractive. The chosen so-
8-62
Chapter 8: Restoration Design
-------
CASEStlJ^Y Careless Creek, Montana
In the Big Snowy Mountains of central Montana,
Careless Creek begins to flow through range-
lands and fields until it reaches the Musselshell
River. At the beginning of the century, the stream
was lined with a riparian cover, primarily of wil-
low. This stream corridor was home to a diversity
of wildlife such as pheasant, beaver, and deer.
In the 1930s, a large reservoir was constructed to
the west with two outlets, one connected to
Careless Creek. These channels were meant to
carry irrigation water to the area fields and on to
the Musselshell River. Heavy flows during the
summer months began to erode the banks
(Figure 8.39a). In the following years, ranchers
began clearing more and more brush for pasture,
sometimes burning it out along a stream.
"My Dad carried farmer's matches in his pocket.
There was a worn spot on his pants where he
would strike a match on his thigh," said Jessie
Zeier, who was raised on a ranch near Careless
Creek, recalling how his father often cleared
brush.
Any remaining willows or other species were
eliminated in the following years as ranchers
began spraying riparian areas to control sage-
brush. This accelerated the streambank erosion
as barren, sometimes vertical, banks began
sloughing off chunks of salted gs devel-
oped to help the planning effort. Many organiza-
tions took part, including the Upper and Lower
Musselshell Conservation Districts; Natural
Resources Conservation Service; Montana
Department of Natural Resources and
Conservation; Montana Department of Fish;
Wildlife and Parks; Deadman's Basin Water
Users Association; U.S. Bureau of Reclamation;
Central Montana RC&D; City of Roundup;
Roundup Sportsmen; county commissioners;
and local landowners.
As part of the planning effort, a geographic
information system resource inventory was
begun in 1993. The inventory revealed about
50 percent of the banks along the 18 miles of
Careless Creek were eroding. The inventory
helped to locate the areas causing the most
problems. Priority was given to headquarters,
corrals, and croplands, where stabilization of
approximately 5,000 feet of streambank has
taken place, funded by EPA monies.
Passive efforts have also begun to stabilize the
banks. Irrigation flows in Careless Creek have
been decreased for the past 5 years, enabling
some areas, such as the one pictured, to begin
to self-heal (Figure 8.39b). Vegetation has been
given a chance to root as erosion has begun to
stabilize. Other practices, such as fencing, are
being implemented, and future treatments are
planned to provide a long-term solution.
Figure 8.39: Careless Creek, (a) Eroded streambank
(May 1995) and (b) streambank in recovery (December
1997).
Streambank Restoration
8-63
-------
Figure 8.38: Eroded bank. Preliminary site
investigation and analyses are critical to
successful streambank stabilization design.
lution, however, must first fulfill the re-
quirement of being effective as bank
stabilization; otherwise, environmental
and economic attributes will be irrele-
vant. Soil bioengineering can be a useful
tool in controlling streambank erosion,
but it should not be considered a
panacea. It must be performed in a judi-
cious manner by personnel experienced
in channel processes, biology, and
streambank stabilization techniques.
Stabilization Techniques
Plants may be established on upper
bank and floodplain areas by using tra-
ditional techniques for seeding or by
planting bare-root and container-grown
plants. However, these approaches pro-
vide little initial resistance to flows, and
plantings may be destroyed if subjected
to high water before they are fully es-
tablished. Cuttings, pole plantings, and
live stakes taken from species that
sprout readily (e.g., willows) are more
resistant to erosion and can be used
lower on the bank (Figure 8.40). In
addition, cuttings and pole plantings
can provide immediate moderation of
flow velocities if planted at high densi-
ties. Often, they can be placed deep
enough to maintain contact with ade-
quate soil moisture levels, thereby elim-
inating the need for irrigation. The
reliable sprouting properties, rapid
growth, and general availability of cut-
tings of willows and other pioneer
species makes them particularly appro-
priate for use in bank revegetation pro-
jects, and they are used in most of the
integrated bank protection approaches
described here (see Figure 8.41).
Anchored Cutting Systems
Several techniques are available that
employ large numbers of cuttings
arranged in layers or bundles, which
can be secured to streambanks and par-
tially buried. Depending on how these
systems are arranged, they can provide
direct protection from erosive flows,
prevent erosion from upslope water
sources, promote trapping of sediments,
and quickly develop dense roots and
sprouts. Brush mattresses and woven
mats are typically used on the face of a
bank and consist of cuttings laid side by
side and interwoven or pinned down
with jute cord or wire held in place by
stakes. Brush layers are cuttings laid on
terraces dug into the bank, then buried
so that the branch ends extend from the
bank. Fascines or wattles are bundles of
cuttings tied together, placed in shallow
trenches arranged horizontally on the
bank face, partially buried, and staked
in place. A similar system, called a reed
roll, uses partially buried and staked
burlap rolls filled with soil and root
material or rooted shoots to establish
herbaceous species in appropriate habi-
tats. Anchored bundles of live cuttings
also have been installed perpendicular
to the channel on newly constructed
gravel floodplain areas to dissipate
floodwater energy and encourage depo-
sition of sediment (Karle and Dens-
more 1994).
8-64
Chapter 8: Restoration Design
-------
dead stout stake
wire secured
to stakes
brush mattress
live and dead stout stake spacing
2 feet on center
16 gauge
wire
branch
cuttings
live stake
geotextile fabric
dead stout stake driven on 2-foot centers
each way, minimum length 2 1/2 feet
Figure 8.40: Cutting systems. Details of brush mattress technique.
Source: USDA-NRCS 1996a.
Note: Rooted/leafed condition of the living plant material is not representative at the time of installation.
Geotextile Systems
Geotextiles have been used for erosion
control on road embankments and
other upland settings, usually in combi-
nation with seeding, or with plants
placed through slits in the fabric. In
self-sustaining streambank applications,
only natural, biodegradable materials
should be used, such as jute or coconut
fiber (Johnson and Stypula 1993). The
typical streambank use for these materi-
als is in the construction of vegetated
geogrids, which are similar to brush lay-
ers except that the fill soils between the
layers of cuttings are encased in fabric,
allowing the bank to be constructed of
successive "lifts" of soil, alternating
with brush layers. This approach allows
reconstruction of a bank and provides
considerable erosion resistance (see
Green River case study). Natural fibers
are also used in "fiber-schines," which
are sold specifically for streambank ap-
plications. These are cylindrical fiber
bundles that can be staked to a bank
with cuttings or rooted plants inserted
through or into the material.
Vegetated plastic geogrids and other
nondegradable materials can also be
used where geotechnical problems re-
quire drainage or additional strength.
Streambank Restoration
8-65
-------
Figure 8.41: Results of live staking along a
streambank. Pioneer species are often most
appropriate for use in bank revegetation
projects.
Integrated Systems
A major concern with the use of struc-
tural approaches to streambank stabi-
lization is the lack of vegetation in the
zone directly adjacent to the water. De-
spite a long-standing concern that vege-
tation destabilizes stone revetments,
there has been little supporting evi-
dence and even some evidence to the
contrary (Shields 1991). Assuming that
loss of conveyance is accounted for, the
addition of vegetation to structures
should be considered. This can involve
placement of cuttings during construc-
tion, or insertion of cuttings and poles
between stones on existing structures.
Timber cribwalls may also be con-
structed with cuttings or rooted plants
extending through the timbers from the
backfill soils.
Trees and Logs
Tree revetments are made from whole
tree trunks laid parallel to the bank,
and cabled to piles or deadman an-
chors. Eastern red cedar (Juniperus vir-
giniana) and other coniferous trees are
used on small streams, where their
springy branches provide interference to
flow and trap sediment. The principal
objective to these systems is the use of
large amounts of cable and the poten-
tial for trees to be dislodged and cause
downstream damage.
Some projects have successfully used
large trees in conjunction with stone to
provide bank protection as well as im-
proved aquatic habitat (see case study).
Large logs with intact root wads are
placed in trenches cut into the bank,
such that the root wads extend beyond
the bank face at the toe (Figure 8.42).
The logs are overlapped and/or braced
with stone to ensure stability, and the
protruding rootwads effectively reduce
flow velocities at the toe and over a
range of flow elevations (Figure 8.43).
A major advantage of this approach is
that it reestablishes one of the natural
roles of large woody debris in streams
by creating a dynamic near-bank envi-
ronment that traps organic material and
provides colonization substrates for in-
vertebrates and refuge habitats for fish.
The logs eventually rot, resulting in a
more natural bank. The revetment sta-
bilizes the bank until woody vegetation
has matured, at which time the channel
can return to a more natural pattern.
In most cases, bank stabilization pro-
jects use combinations of the tech-
niques described above in an integrated
approach. Toe protection often requires
the use of stone, but amounts can be
greatly reduced if large logs can also be
used. Likewise, stone blankets on the
bank face can be replaced with geogrids
or supplemented with interstitial plant-
ings. Most upper bank areas can usually
be stabilized using vegetation alone,
although anchoring systems might be
required. The Green River bank restor-
ation case study illustrates one success-
ful application of an integrated approach
on a moderate-sized river in Washing-
ton State.
8-66
Chapter 8: Restoration Design
-------
existing vegetation, plantings or
soil bioengineering systems
Figure 8.42: Revet-
ment system. Details
of rootwad and
boulder technique.
Source: USDA-NRCS
1996a.
thalweg channel
footer log
boulder 1 1/2 times
diameter of log
Figure 8.43: Installation of logs with intact
root wads. An advantage to using tree revet-
ments is the creation of habitat for inverte-
brates and fish along the streambank.
Streambank Restoration
8-67
-------
CASE51UPY Green River Bank Restoration Initiative
f^J King County, Washington
The King County, Washington, Surface Water
Management Division initiated a bank
restoration initiative in 1994 that illustrates a vari-
ety of project objectives and soil bioengineering
approaches (Figure 8.44). The project involved
stabilization of the bank of the Green River along
a 500-foot section of a meander bend that was
rapidly migrating into the adjacent farm field.
The project objectives included improvement of
Typical Cross-Section of Restored Bank
Section View
(a)
Typical Detail Log Pattern
Plan View
EXtSTiHCr TOS.
OF &A*tfi *r L.OVJ M
(b)
Figure 8.44: Construction details.
Source: King County Surface Water Management Division.
fish and wildlife habitat, particularly for
salmonids.
Site investigations included surveys of stream
cross sections, velocity measurements at two dis-
charge levels, soil characterizations, and assess-
ment of fish use of existing habitat features in
the area. The streambank was vertical, 5 to 10
feet high, and composed of silty-clay-loam alluvi-
um with gravel lenses. Flow velocities were 2 to 5
fps for flows of 200 and 550 cfs. Fish were pri-
marily observed in areas of low velocities and/or
near woody debris, and along the channel mar-
gins.
In August, large woody debris was installed along
the toe of the bank. The logs were cedar and fir,
25 feet long and 28 to 36 inches in diameter,
with root wads 6 to 8 feet in diameter. The logs
were placed in trenches cut 15 feet back into the
bank so that the root wads extended into the
channel, and large (3- to 4-foot diameter) boul-
ders were placed among the logs at the toe. Log
and boulder placement was designed to interlock
and brace the logs and prevent movement. The
project used approximately 10 logs and 20 boul-
ders per 100 lineal feet of bank. In September,
vegetated geogrids were installed above the toe
zone to stabilize the high bank (Figure 8.45)
The project was completed with installation of a
variety of plants, including container-grown
conifers and understory species, in a minimum
25-foot buffer along the top of the bank.
Within 2 months of completion, the site was sub-
jected to three high flows, including an 8,430-cfs
event in December 1994. Measured velocities
along the bank were less than 2 fps at the sur-
face and less than 1 fps 2 feet below the surface,
indicating the effectiveness of the root wads in
moderating flow velocities (Figure 8.46). Some
surface erosion and washout of plants along the
top bank occurred, and a subsequent event
caused minor damage to the geogrid at one loca-
tion. The maintenance repairs consisted of
replanting and placement of additional logs to
8-68
Chapter 8: Restoration Design
-------
Figure 8.45: Partially installed vegetated geogrid.
Installed above the toe to stabilize high bank.
Figure 8.46: Completed system. Note calm water
along bankline during high flow.
halt undermining of the geogrid. The 1995 grow-
ing season produced dramatic growth of the wil-
low cuttings in the geogrid, although many of
the planted trees in the overbank zone died
(Figure 8.47). Initial observations have document-
ed extensive fish use of the slow-water habitats
among the root wads at the toe of the bank, and
in scour holes created by flows deflected toward
the channel bottom.
The site continues to be carefully monitored, and
the effectiveness of the approach has led to the
implementation of similar designs elsewhere in
the region. The project designers have concluded
that future projects of this type should use small
plants rather than large rooted material in the
overbank zone to reduce costs, improve survival,
and minimize damage due to equipment access
for maintenance or repair. Based on their obser-
vations of fish response along the restored bank
and in nearby stream reaches, they also recom-
mend that future projects incorporate a greater
variety of woody debris, including brushy material
and tree tops, along the toe and lower bank.
Figure 8.47: Completed system after one year. Note
dramatic willow growth from vegetated geogrid.
Streambank Restoraton
8-69
-------
8.G Instream Habitat Recovery
As described in Chapter 2, habitat is the
place where a population lives and in-
cludes living and nonliving compo-
nents. For example, fish habitat is a
place, or set of places, in which a single
fish, a population, or an assemblage of
fish can find the physical, chemical,
and biological features needed for life,
including suitable water quality, passage
routes, spawning grounds, feeding and
resting sites, and shelter from predators
and adverse conditions (Figure 8.48).
Principal factors controlling the quality
of the available aquatic habitat include:
Streamflow conditions.
Physical structure of the channel.
Water quality (e.g., temperature, pH,
dissolved oxygen, turbidity, nutrients,
alkalinity).
The riparian zone.
Other living components.
The existing status of aquatic habitats
within the stream corridor should be
assessed during the planning stage
(Part II). Design of channels, structures,
or restoration features can be guided
and fine tuned by assessing the quality
and quantity of habitats provided by
the proposed design. Additional guid-
ance on assessing the quantity and qual-
ity of aquatic habitat is provided in
Chapter 7.
This section discusses the design of in-
stream habitat structures for the pur-
pose of enhancing physical aquatic
habitat quality and quantity. It should
be noted, however, that the best ap-
proach to habitat recovery is to restore a
fully functional, well-vegetated stream
corridor within a well-managed water-
shed. Man-made structures are less sus-
tainable and rarely as effective as a
stable channel. Over the long term,
design should rely on natural fluvial
processes interacting with floodplain
vegetation and associated woody debris
to provide high-quality aquatic habitat.
Structures have little effect on popula-
tions that are limited by factors other
than physical habitat.
Figure 8.48: Instream habitat. Suitable water quality, passage routes, and spawning grounds are
some of the characteristics of fish habitat.
8-70
Chapter 8: Restoration Design
-------
Instream Habitat Features
The following procedures to restore in-
stream habitat are adapted from New-
bury and Gaboury (1993) and Garcia
(1995).
Select stream. Give priority to reaches
with the greatest difference between
actual (low) and potential (high) fish
carrying capacity and with a high
capacity for natural recovery processes.
Evaluate fish populations and their
habitats. Give priority to reaches with
habitats and species of special inter-
est. Is this a biological, chemical,
or physical problem? If a physical
problem:
Diagnose physical habitat problems.
Drainage basin. Trace watershed
lines on topographical and geolog-
ical maps to identify sample and
rehabilitation basins.
Profiles. Sketch main stem and
tributary long profiles to identify
discontinuities that might cause
abrupt changes in stream charac-
teristics (falls, former base levels,
etc.).
Flow. Prepare flow summary for
rehabilitation reach using existing
or nearby records if available
(flood frequency, minimum flows,
historical mass curve). Correct for
drainage area differences. Compare
magnitude and duration of flows
during spawning and incubation
to year class strength data to deter-
mine minimum and maximum
flows required for successful repro-
duction.
Channel geometry survey. Select
and survey sample reaches to
establish the relationship between
channel geometry, drainage area,
and bankfull channel-forming dis-
charge (Figure 8.49). Quantify
hydraulic parameters at design
discharge.
Rehabilitation reach survey. Survey
rehabilitation reaches in sufficient
detail to prepare channel cross
section profiles and construction
drawings and to establish survey
reference markers.
Preferred habitat. Prepare a sum-
mary of habitat factors for biologi-
cally preferred reaches using
regional references and surveys.
Identify multiple limiting factors
for the species and life stages of
greatest concern. Where possible,
undertake reach surveys in refer-
ence streams with proven popula-
tions to identify local flow condi-
tions, substrate, refugia, etc.
Design a habitat improvement plan.
Quantify the desired results in terms
of hydraulic changes, habitat im-
provement, and population increas-
es. Integrate selection and sizing of
rehabilitation works with instream
flow requirements.
Select potential schemes and struc-
tures that will be reinforced by the
Man-made
structures are
less sustain-
able and rarely
as effective as
a stable
channel.
Figure 8.49: Surveying a stream. Channel
surveys establish baseline information
needed for restoration design.
Instream Habitat Recovery
8-71
-------
FAST
FORWARD
Preview Chap-
ter 9 for an
introduction to
construction
and monitoring
follow-up
activities.
existing stream dynamics and
geometry. The following section
provides additional detail on use
of habitat structures.
Test designs for minimum and
maximum flows and set target
flows for critical periods derived
from the historical mass curve.
Implement planned measures.
Arrange for on-site location and
elevation surveys and provide
advice for finishing details in the
stream.
Monitor and evaluate results.
Arrange for periodic surveys of the
rehabilitated reach and reference
reaches, to improve the design,
as the channel ages.
Instream Habitat Structures
Aquatic habitat structures (also called
instream structures and stream im-
provement structures) are widely used
in stream corridor restoration. Com-
mon types include weirs, dikes, random
rocks, bank covers, substrate reinstate-
ment, fish passage structures, and off-
channel ponds and coves. Institutional
factors have favored their use over more
holistic approaches to restoration. For
example, it is often easier to obtain au-
thority and funding to work within a
channel than to influence riparian or
watershed land use. Habitat structures
have been used more along cold water
streams supporting salmonid fisheries
than along warm water streams, and the
voluminous literature is heavily
weighted toward cold water streams.
In a 1995 study entitled Stream Habitat
Improvement Evaluation Project, 1,234
structures were evaluated according to
their general effectiveness, the habitat
quality associated with the given struc-
ture type, and actual use of the struc-
tures by fish (Bio West 1995). The study
determined approximately 18 percent
of the structures need maintenance.
Where inadequate flows and excessive
sediment delivery occur, structures have
a brief lifespan and limited value in
terms of habitat improvement. Further-
more, the study concluded that in-
stream habitat structures generally
provided increased fish habitat.
Before structural habitat features are
added to a stream corridor restoration
design, project managers should care-
fully determine whether they address
the real need and are appropriate.
Major caveats include the following:
Structures should never be viewed as
a substitute for good riparian and
upland management.
Defining the ecological purpose of a
structure and site selection are as
important as construction technique.
Scour and deposition are natural
stream processes necessary to create
fish habitat. Overstabilization there-
fore limits habitat potential, whereas
properly designed and sited struc-
tures can speed ecological recovery.
Use of native materials (stone and
wood) is strongly encouraged.
Periodic maintenance of structures
will be necessary and must be incor-
porated into project planning.
Instream Habitat Structure
Design
Design of aquatic habitat structures
should proceed following the steps pre-
sented below (Shields 1983). However,
the process should be viewed as itera-
tive, and considerable recycling among
steps should be expected.
Plan layout.
Select types of structures.
Size the structures.
Investigate hydraulic effects.
8-72
Chapter 8: Restoration Design
-------
Consider effects on sediment trans-
port.
Select materials and design structures.
Each step is described below. Construc-
tion and monitoring follow-up activi-
ties are described in Chapter 9.
Plan Layout
The location of each structure should
be selected. Avoid conflicts with bridges,
riparian structures, and existing habitat
resources (e.g., stands of woody vegeta-
tion). The frequency of structures should
be based on the habitat requirements
previously determined, within the con-
text of the stream morphology and
physical characteristics (see Chapter 7).
Care should be taken to place structures
where they will be in the water during
baseflow. Structures should be spaced
to avoid large areas of uniform condi-
tions. Structures that create pools
should be spaced five to seven channel
widths apart. Weirs placed in series
should be spaced and sized carefully to
avoid placing a weir within the backwa-
ter zone of the downstream structure,
since this would create a series of pools
with no intervening riffles or shallows.
Select Types of Structures
The main types of habitat structures are
weirs, dikes (also called jetties, barbs,
deflectors (Figure 8.50), spurs, etc.),
random rocks (also called boulders),
and bank covers (also called lunkers).
Substrate reinstatement (artificial rif-
fles), fish passage structures, and off-
channel ponds and coves have also
been widely employed. Fact sheets on
several of these techniques are provided
in the Techniques Appendix, and numer-
ous design web sites are available
(White and Brynildson 1967, Seehorn
1985, Wesche 1985, Orsborn et al.
1992, Orth and White 1993, Flosi and
Reynolds 1994).
Cross Section
not to scale
rock riprap
Front Elevation
not to scale
key into
streambed
approx.
Figure 8.50: Instream habitat structure.
Wing deflector habitat structure.
Source: USDA-NRCS 1996a.
Instream Habitat Recovery
8-73
-------
Evidence suggests that traditional de-
sign criteria for widespread bank and
bed stabilization measures (e.g., con-
crete grade control structures, homoge-
neous riprap) can be modified, with no
functional loss, to better meet environ-
mental objectives and improve habitat
diversity. Table 8.7 may be used as a
general guide to relate structural type to
habitat requirement. Weirs are generally
more failure-prone than deflectors.
Deflectors and random rocks are mini-
mally effective in environments where
higher flows do not produce sufficient
local velocities to produce scour holes
near structures. Random rocks (boul-
ders) are especially susceptible to un-
dermining and burial when placed in
sand-bed channels, although all types
of stone structures experience similar
problems. Additional guidance for eval-
uating the general suitability of various
fish habitat structures for a wide range
of morphological stream types is pro-
vided by Rosgen (1996). Seehorn
(1985) provides guidance for small
streams in the eastern United States.
The use of any of these guides should
also consider the relative stability of
the stream, including aggradation
and incision trends, for final design.
Size the Structures
Structures should be sized to produce
the desired aquatic habitats at the nor-
mal range of flows from baseflow to
bankfull discharge. A hydrological
analysis can provide an estimate of the
normal range of flows (e.g., a flow du-
ration curve), as well as an estimate of
extreme high and low flows that might
be expected at the site (see Chapter 7).
In general, structures should be low
enough that their effects on the water
surface profile will be slight at bankfull
discharge. Detailed guidance by struc-
tural type is presented in the Tech-
niques Appendix. For informal design,
empirical equations like those pre-
sented by Heiner (1991) can be used to
roughly estimate the depth of scour
holes at weirs and dikes.
Investigate Hydraulic Effects
Hydraulic conditions at the design flow
should provide the desired habitat;
however, performance should also be
evaluated at higher and lower flows.
Barriers to movement, such as ex-
tremely shallow reaches or vertical
drops not submerged at higher flows,
should be avoided. If the conveyance of
the channel is an issue, the effect of the
proposed structures on stages at high
flow should be investigated. Structures
may be included in a standard backwa-
ter calculation model as contractions,
low weirs, or increased flow resistance
(Manning) coefficients, but the amount
of increase is a matter of judgment or
limited by National Flood Insurance
Program ordinances. Scour holes should
be included in the channel geometry
downstream of weirs and dike since a
major portion of the head loss occurs
in the scour hole. Hydraulic analysis
should include estimation or computa-
tion of velocities or shear stresses to be
experienced by the structure.
Consider Effects on Sediment
Transport
If the hydraulic analysis indicates a
shift in the stage-discharge relation-
ship, the sediment rating curve of the
restored reach may change also, lead-
ing to deposition or erosion. Although
modeling analyses are usually not cost-
effective for a habitat structure design
effort, informal analyses based on as-
sumed relationships between velocity
and sediment discharge at the bankfull
discharge may be helpful in detecting
potential problems. An effort should
be made to predict the locations and
magnitude of local scour and deposi-
8-74
Chapter 8: Restoration Design
-------
Table 8.7: Fish habitat improvement structuressuitability for stream types.
Source: Rosgen 1996.
1 Channel
Type
A1
B1-1
B1
B2
B3
B4
C1-1
C2
OEZ]
C4
C6
D1
D2
Channel I
Type
A1
~A2 |
B1-1
B1
B2
Low St.
Check Dam
N/A
N/A
Poor
Excellent
Excellent
Fair
Fair
Fair
Poor
Good
Excellent
Fair
Fair
Fair
N/A
Fair
Fair
Half Log
Cover
N/A
N/A
Good
Good
Excellent
B3 Poor
B4 Poor
B5 Poor
C1-1 Good
C1 Good
C2 Good
~C3~~ Fair
C4
C5
C6
D1
D2
Key:
Excellent
Good
Fair
Poor
Poor
N/A
1 Medium St.
| Check Dam
N/A
N/A
Poor
Excellent
Good
Poor
Poor
Poor
Poor
Fair
Good
Poor
Poor
Poor
N/A
Poor
Poor
(Floating
Log Cover
N/A
N/A
Good
Excellent
Excellent
Fair
Fair
Fair
Good
Good
Excellent
Good
Good
Good
N/A
1 Boulder
Placement
N/A
N/A
Good
N/A
Excellent
Poor
Poor
Poor
Fair
Fair
Good
Poor
Poor
Poor
N/A
Poor
Poor
IBank Boulder
Placement
N/A
N/A
Excellent
N/A
Excellent
Good
Good
Good
Excellent
Excellent
Excellent
Good
Good
Good
N/A
Fair
Fair
(Submerged Shelter
Meander
N/A
N/A
Good
Excellent
Good
Fair
Fair
Fair
Good
Good
Excellent
Fair
Fair
Fair
N/A
Straight
N/A
N/A
Excellent
Excellent
Excellent
Fair
Fair
Fair
Excellent
Excellent
Excellent
Good
Good
Good
N/A
Single Wing
Deflector
N/A
N/A
Poor
Excellent
Excellent
Poor
Poor
Poor
Poor
Good
Good
Fair
Poor
Poor
N/A
Fair
Fair
Migration
Excellent
Excellent
Fair
Excellent
Good
Poor
Poor
Poor
Poor
Poor
Poor
Poor
Poor
Poor
Poor
Double Wing
Deflector
N/A
N/A
Poor
Excellent
Excellent
Poor
Poor
Poor
Poor
Good
Excellent
Fair
Poor
Poor
N/A
Fair
Fair
Gravel Traps
"V" Shaped
Good
Excellent
Good
Excellent
Good
Poor
Poor
Poor
Fair
Fair
Good
N/A
Poor
Poor
Poor
Poor Poor Poor Poor Poor Poor
Poor Poor Poor Poor Poor N/A
No limitation to location of structure placement or special modification in design.
Under most conditions, very effective. Minor modification of design or placement required.
Serious limitation which can be overcome by placement location, design modification, or stabilization techniques.
Channel
Constrictor
N/A
N/A
Poor
N/A
Excellent
Poor
Poor
Poor
Poor
Fair
Excellent
Fair
Poor
Poor
N/A
Fair
Fair
Log
Poor
Excellent
Good
Excellent
Good
Poor
Poor
Poor
Fair
Good
Excellent
N/A
Poor
Poor
Fair
N/A
Poor
IBank
Cover
N/A
N/A
Good
Excellent
Excellent
Poor
Poor
Poor
Good
Good
Good
Good
1
j
D
_j
H
1
Fair
Poor
N/A
Poor
Poor
^ Gravel
Poor
Poor
Fair
fair
Good
Poor
Poor
Poor
Fair
Fair
Excellent
N/A
Poor
Poor
Fair
Poor
Poor
1
3
3
I
3
i
Generally not recommended due to difficulty of offsetting potential adverse consequences and high probability of reduced effectiveness.
Poor - Not recommended due to morphological character of stream type and very low probability of success.
Not Applicable- Generally not considered since habitat components are not limiting.
Note : A3, A3-a, A4, A4-a, AS, A5-a channel types are not evaluated due to limited fisheries value.
Instream Habitat Recovery
8-75
-------
tion. Areas projected to experience sig-
nificant scour and deposition should
be prime sites for visual monitoring
after construction.
Select Materials
Materials used for aquatic habitat struc-
tures include stone, fencing wire, posts,
and felled trees. Priority should be
given to materials that occur on site
under natural conditions. In some
cases, it may be possible to salvage rock
or logs generated from construction of
channels or other project features. Logs
give long service if continuously sub-
merged. Even logs not continuously wet
can give several decades of service if
chosen from decay-resistant species.
Logs and timbers must be firmly fas-
tened together with bolts or rebar and
must be well anchored to banks and
bed. Stone size should be selected
based on design velocities or shear
stress.
8.H Land Use Scenarios
As discussed in Chapter 3, most stream
corridor degradation is directly attribut-
able to land use practices and/or hydro-
logic modifications at the watershed
level that cause fundamental disruption
of ecosystem functions (Beschta et al.
1994) (Figure 8.51). Ironically, land
use practices, including hydrologic
modifications, can offer the opportu-
nity for restoring these same degraded
stream corridors. Where feasible, the
Figure 8.51: Sediment-laden stream. Most
stream corridor degradation can be attributed
to impacts resulting from surrounding land
uses.
objective of the restoration design
should be to eliminate or moderate
disruptive influences sufficiently to
allow recovery of dynamic equilibrium
overtime (NRG 1992).
If chronic land use impacts on the
stream or riparian system cannot be
controlled or moderated, or if some
elements of the stream network (e.g.,
headwaters) are not included in the
restoration design, it must be recog-
nized that the restoration action may
have limited effectiveness in the long-
term.
Restoration measures can be designed
to address particular, site-specific de-
ficiencies (an eroding bank, habitat
features), but if they do not restore
self-maintaining processes and the
functions of a stream corridor, they
must be regarded as a focused "fix"
rather than an ecosystem restoration.
In cases where land use practices are
the direct cause of stream corridor
degradation and there is a continuing
downward trend in landscape condi-
tion, there is little point in expending
resources to address symptoms of the
problem rather than the problem itself
(DeBano and Schmidt 1989).
8-76
Chapter 8: Restoration Design
-------
Design Approaches for
Common Effects
Agriculture, forestry, grazing, mining,
recreation, and urbanization are some
of the principal land uses that can re-
sult in disturbance of stream corridor
structure and functions. A watershed
analysis will help prioritize and coordi-
nate restoration actions (Platts and
Rinne 1985, Swanson 1989) and may
indicate critical or chronic land use ac-
tivities causing disturbance both inside
and outside the stream corridor. Ad-
dressing these in the restoration plan
and design, may greatly improve the
effectiveness and success of restoration
work.
Restoration measures designed in re-
sponse to these effects may be similar
across land uses. Sediment and nutrient
management in urban, agricultural, and
forest settings, for instance, may require
the use of buffer strips. Although the
buffer strips have many common design
characteristics, each setting has site-
specific factors.
Dams
Dams alter the flow of water, sediment,
organic matter, and nutrients, resulting
in both direct physical and indirect bio-
logical effects in tailwaters and down-
stream riparian and floodplain areas
(see Chapter 3). Stream corridors below
dams can be partially restored by modi-
fying operation and management ap-
proaches. Impacts from the operation
of dams on surface water quality and
aquatic and riparian habitat should be
assessed and the potential for improve-
ment evaluated. The modification of
operation approaches, where possible,
in combination with the application of
properly designed and applied best
management practices, can reduce the
impacts caused by dams on down-
stream riparian and floodplain habitats.
Best management practices can be ap-
plied individually or in combination to
protect and improve surface water qual-
ity and aquatic habitat in reservoirs as
well as downstream. Several approaches
have been designed for improving or
maintaining acceptable levels of dis-
solved oxygen (DO), temperature, and
other constituents in reservoirs and tail-
waters. One design approach uses
pumps, air diffusers, or air lifts to in-
duce circulation and mixing of the
oxygen-poor but cold hypolimnion
with the oxygen-rich but warm epil-
imnion, resulting in a more thermally
uniform reservoir with increased DO.
Another design approach for improving
water quality in tailwaters for trout fish-
eries involves mixing of air or oxygen
with water passing through the turbines
at hydropower dams to improve con-
centrations of DO. Reservoir waters can
also be aerated by venting turbines to
the atmosphere or by injecting com-
pressed air into the turbine chamber
(USEPA 1993).
Modification to the intakes, the spill-
way, or the tailrace of a dam can also be
designed to improve temperature or
DO levels in tailwaters. Installing vari-
ous types of weirs downstream of a
dam achieves similar results. These de-
sign practices rely on agitation and tur-
bulence to mix reservoir releases with
atmospheric air to increase levels of DO
(USEPA 1993).
Adequate fish passage around dams, di-
versions, and other obstructions may be
a critically important component of
restoring healthy fish populations to
previously degraded rivers and streams.
A fact sheet in Appendix A shows an
example for fish passages. However,
designing, installing, and operating fish
passage facilities at dams are beyond
the scope of this handbook. Further,
the type of fish passage facility and the
flows necessary for operation are gener-
Land Use Scenarios
8-77
-------
ally site specific. Further information
on fish passage technology can be
found in other references, including
Environmental Mitigation at Hydroelec-
tric Projects - Volume II. Benefits and
Costs of Fish Passage and Protection
(Francfort et al., 1994); and Fish Passage
Technologies: Protection at Hydropower
Facilities (Office of Technology Assess-
ment, Congress of the United States,
Washington DC, OTA-ENV-641).
Adjusting operation procedures at some
dams can also result in improved qual-
ity of reservoir releases and downstream
conditions. Partial restoration of stream
corridors below dams can be achieved
by designing operation procedures that
mimic the natural hydrograph, or desir-
able aspects of the hydrograph. Modifi-
cations include scheduling releases or
the duration of shutoff periods, institut-
ing procedures for the maintenance of
minimum flows, and making seasonal
adjustments in pool levels and in the
timing and variation of the rates of
drawdowns (USEPA 1993).
Modifying operation and management
approaches, in combination with the
application of properly designed best
management practices, can be an effec-
tive approach to partially restoring
stream corridors below dams. However,
dam removal is the only way to begin
to fully restore a stream to its natural
condition. It is important to note, how-
ever, that unless accomplished very
carefully, with sufficient studies and
modeling and at significant cost, re-
moving a dam can cause more damage
downstream (and upstream) than the
dam is currently causing until a state of
dynamic equilibrium is reached. Dam
removal lowers the base level of up-
stream tributaries, which can cause reju-
venation, bed and bank instability, and
increased sediment loads. Dam removal
can also result in the loss of wetlands
and habitat in the reservoir and tribu-
tary deltas.
Three options should be considered
complete removal, partial removal, and
staged breaching. The option is selected
based on the condition of the dam and
future maintenance required if not
completely removed, and on the best
way to deal with the sediment now
stored behind the dam. The following
elements must be considered in manag-
ing sediment:
Removing features of dams necessary
to restore fish passage and ensure
safety.
Revegetation of the reservoir areas.
Long-term monitoring of sediment
transport and river channel topo-
graphy, water quality, and aquatic
ecology.
Long-term protection of municipal
and industrial water supplies.
Mitigation of flood impacts caused
by long-term river aggradation.
Quality of sediment, including iden-
tification of the lateral and vertical
occurrence of toxic or otherwise
poor-quality sediment.
Water quality issues are primarily re-
lated to suspended sediment concentra-
tion and turbidity. These are important
to municipal, industrial, and private
water users, as well as to aquatic com-
munities. Water quality will primarily
be affected by any silt and clay released
from the reservoirs and by reestablish-
ment of the natural sediment loads
downstream. During removal of the
dam and draining of the lake, the un-
vegetated reservoir bottoms will be ex-
posed. Lakebeds will be expected to
have large woody debris and other or-
ganic material. A revegetation program
is necessary to control dust, surface
runoff, and erosion and to restore habi-
8-78
Chapter 8: Restoration Design
-------
tat and aesthetic values. A comprehen-
sive sediment management plan is
needed to address the following:
Sediment volume and physical prop-
erties.
Sediment quality and associated dis-
posal requirements.
Hydraulic and biological characteris-
tics of the reservoir and downstream
channel.
Alternative measures for sediment
management.
Impacts on downstream environ-
ment and channel hydraulics.
Recommended measures to manage
sediment properly and economically.
Objectives of sediment management
should include flood control, water
quality, wetlands, fisheries, habitat, and
riparian rights.
For hydropower dams, the simplest de-
commissioning program is to dismantle
the turbine-generator and seal the water
passages, leaving the dam and water-
retaining structures in place. No action
is taken concerning the sediments since
they will remain in the reservoir and the
hydraulic and physical characteristics of
the river and reservoir will remain essen-
tially unchanged. This approach is vi-
able only if there are no deficiencies in
the water-retaining structures (such as
inadequate spillway capacity or inade-
quate factors of safely for stability) and
long-term maintenance is ensured. In
some cases, decommissioning can in-
clude partial removal of water-retaining
structures. Partial removal involves de-
molition of a portion of the dam to
create a breach so that it no longer
functions as a water-retaining structure.
For additional information, see Guide-
lines for the Retirement of Hydroelectric
Facilities published by the American So-
ciety of Civil Engineers (ASCE) in 1997.
Channelization and Diversions
Channelization and flow diversions
represent forms of hydrologic modifica-
tion commonly associated with most
principal land uses, and their effects
should be considered in all restoration
efforts (see Chapter 3). In some cases,
restoration design can include the re-
moval or redesign of channel modifica-
tions to restore preexisting ecological
and flow characteristics.
Modifications of existing projects, in-
cluding operation and maintenance or
management, can improve some nega-
tive effects without changing the exist-
ing benefits or creating additional
problems. Levees may be set back from
the stream channel to better define the
stream corridor and reestablish some or
all of the natural floodplain functions.
Setback levees can be constructed to
allow for overbank flooding, which pro-
vides surface water contact with stream-
side areas such as floodplains and
wetlands.
Instream modifications such as uniform
cross sections or armoring associated
with channelization or flow diversions
may be removed, and design and place-
ment of meanders can be used to
reestablish more natural channel char-
acteristics. In many cases, however, ex-
isting land uses might limit or prevent
the removal of existing channel or
floodplain modifications. In such cases,
restoration design must consider the ef-
fects of existing channel modifications
or flow diversions, in the corridor and
the watershed.
Exotic Species
Exotic species are another common
problem of stream corridor restoration
and management. Some land uses have
actually introduced exotics that have be-
come uncontrolled, while others have
merely created an opportunity for such
Land Use Scenarios
8-79
-------
CASE5IUDY The Multispecies Riparian Buffer
JS System in the Bear Creek, IA
* Watershed
Introduction
The Bear Creek Watershed in central Iowa is a
small (26.8 mi2) drainage basin located with-
in the Des Moines Lobe subregion of the Western
Com Belt Plains ecoregion, one of the youngest
and flattest ecological subregions in Iowa. In gen-
eral, the land is level to gently rolling with a poor-
ly developed stream network. Soils of the region
are primarily developed in glacial till and alluvial,
lacustrine, and windblown deposits. Prior to
European settlement of the region (ca 1847) the
watershed consisted of the vast tallgrass prairie
ecosystem, interspersed with wet prairie marshes
in topographic lows and gallery forests along
larger order streams and rivers. Native forest was
limited to the Skunk River corridor into which
Bear Creek flows.
Subsequent conversion of the land, including the
riparian zone, from native vegetation to row
crops, extensive subsurface drainage tile installa-
tion, dredge ditching, and grazing of fenced
riparian zones have resulted in substantial stream
channel modification. Records suggest that artifi-
cial drainage of marshes and low prairies in the
upper reaches of the Bear Creek watershed was
completed about 1902, with ditch dredging com-
pleted shortly thereafter. While the main stream
pattern appears to have remained about the
same since that time, significant channelization
continued into the 1970s. Additional intermittent
channels have developed in association with new
drainage tile and grass waterway installation.
Present land use in the Bear Creek watershed is
typical of the region, with over 87% of the land
area devoted to row crop agriculture.
Landscape modifications and present land-use
practices have produced nonpoint source pollu-
tion in the watershed, which landowners have
addressed by implementing soil conservation
practices (e.g. reduced tillage, terracing, grass
waterways) and better chemical input manage-
ment (e.g. more accurate and better timed appli-
cations). It has only been recently that placement
or enhancement of riparian vegetation or
"streamside filter strips" has been recommended
to reduce sediment and chemical loading, modify
flow regime by reducing discharge extremes,
improve structural habitat, and restore energy
relationships through the addition of organic
matter and reduction in temperature and dis-
solved oxygen extremes.
The Riparian Management System
(RiMS)
The Agroecology Issue Team of the Leopold
Center for Sustainable Agriculture, Iowa State
University, Ames, IA, is conducting research on
the design and establishment of an integrated
riparian management system (RiMS) to demon-
strate the benefits of properly functioning riparian
buffers in the heavily row-cropped landscape of
the midwestern U.S. The purpose of the RiMS is
to restore the essential ecological functions that
riparian ecosystems once provided. Specific objec-
tives of such buffers are to intercept eroding soil
and agricultural chemicals from adjacent crop
fields, slow floodwaters, stabilize streambanks,
provide wildlife habitat, and improve the biologi-
cal integrity of aquatic ecosystems. The regional-
ization of this system has been accomplished by
designing it with several components, each of
which can be modified to fit local landscape con-
ditions and landowner objectives.
The Agroecology Issue Team is conducting
detailed studies of important biological and physi-
cal processes at both the field and watershed
scale to provide the necessary data to allow
resource managers to make credible recommen-
dations of buffer placement and design in a wide
variety of landscapes. In addition, socioeconomic
data collected from landowners in the watershed
are being used to identify landowner criteria for
accepting RiMS. The team also is quantifying the
non-market value placed on the improvement in
surface and ground water quality.
8-80
Chapter 8: Restoration Design
-------
The actual development and establishment of the
RIMS along Bear Creek was initiated in 1990
along a 0.6-mile length of Bear Creek on the Ron
and Sandy Risdal Farm. The buffer strip system
has subsequently been planted along 3.5 miles of
Bear Creek upstream from this original site. The
RiMS consists of three components: 1) a multi-
species riparian buffer (MRB), 2) soil bioengineer-
ing technologies for streambank stabilization, and
3) constructed wetlands to intercept and process
nonpoint source pollutants in agricultural
drainage tile water.
Multi-species Riparian Buffer (MRB)
The general MRB consists of three zones. The
rapid growth of this buffer community can
change a heavily impacted riparian zone into a
functioning riparian ecosystem in a few short
years. The combinations of trees, shrubs, and
native grasses can be modified to fit site condi-
tions (e.g. soils, slope), major buffer biological
and physical function(s), owner objectives, and
cost-share program requirements.
Soil Bioengineering
It has been estimated that greater than 50% of
the stream sediment load in small watersheds in
the Midwest is the result of channel erosion. This
problem has been worsened by the increased ero-
sive power of streams resulting from stream
channelization and loss of riparian vegetation.
Several different soil bioengineering techniques
have been employed in the Bear Creek water-
shed. These include the use of willow posts and
stakes driven into the bank, live willow fascines,
live willow brush mattresses, and biodegradable
geotextile anchored with willow stakes on bare
slopes. Alternatives used to stabilize the base of
the streambank include rock and anchored dead
plant material such as cedar or bundled maple.
Constructed Wetlands
Small, constructed wetlands which are integrated
into the riparian buffer have considerable poten-
tial to remove nitrate and other chemicals from
the extensive network of drain tile in the
Midwest. To demonstrate this technology, a small
(600y ) wetland was constructed to process
drainage tile water from a 12-acre cropped field.
The wetland was constructed by excavating a
depressional area near the creek and constructing
a low berm. The subsurface drainage tile was
rerouted to enter the wetland at a point that
maximizes residence time of drainage tile water
within the wetland. A simple gated water level
control structure at the wetland outlet provides
control of the water level maintained within the
wetland. Cattail rhizomes (Typha glauca Godr.)
collected from a local marsh and road ditch were
planted within the wetland and native grasses
and forbs planted on the constructed berm.
Future plans include the construction of addition-
al tile drainage wetlands within the Bear Creek
watershed.
System Effectiveness
Long-term monitoring has demonstrated the sig-
nificant capability of the RiMS to intercept erod-
ing soil from adjacent cropland, intercept and
process agricultural chemicals moving in shallow
subsurface water, stabilize stream channel move-
ment, and improve instream environments, while
also providing wildlife habitat and quality timber
products. The buffer traps 70-80% of the sedi-
ment carried in surface runoff and has reduced
nitrate and atrazine moving in the soil solution to
levels well below the maximum contaminant lev-
els specified by the USE PA. Streambank bioengi-
neering systems have virtually stopped bank ero-
sion along treated reaches and are now trapping
channel sediment. The constructed wetland has
reduced nitrate in the tile drainage water by as
much as 80% depending on the season of the
year. Wildlife benefits have also appeared in a
very short time, with a nearly fivefold increase in
bird species diversity observed within the buffer
strip versus an adjacent, unprotected stream
reach.
While the RiMS function is being assessed through
experimental plot work with intensive process
monitoring, economic benefits and costs to
landowners and society also are being deter-
mined. Landowners surveys, focus groups, and
one-on-one interviews have identified the concern
that water quality should be improved by reduc-
ing chemical and sediment inputs by as much as
50%. Landowners are willing to pay for this
improved water quality as well as volunteer their
time to help initiate the improvements.
Land Use Scenarios
8-81
-------
CASESTU^Y The Multispecies Riparian Buffer
Jy System in the Bear Creek, IA
Watershed (continued)
While the RiMS can effectively intercept and treat
nonpoint source pollution from the uplands, it
should be stressed that a riparian management
system cannot replace upland conservation prac-
tices. In a properly functioning agricultural land-
scape, both upland conservation practices and an
integrated riparian system contribute to achieving
environmental goals and improved ecosystem
functioning.
Support for this work is from the Leopold Center
for Sustainable Agriculture, the Iowa Department
of Natural Resources through a grant from the
USEPA under the Federal Nonpoint Source
Management Program (Section 319 of the Clean
Water Act), and the USDA (Cooperative State
Research Education and Extension Service),
National Research Initiative Competitive Grants
Program, and the Agriculture in Concert with the
Environment Program.
exotics to spread. Again, control of ex-
otic species has some common aspects
across land uses, but design approaches
are different for each land use.
Control of exotics in some situations
can be extremely difficult and may be
impractical if large acreages or well-
established populations are involved.
Use of herbicides may be tightly regu-
lated or precluded in many wetland and
streamside environments, and for some
exotic species there are no effective con-
trol measures that can be easily imple-
mented over large areas (Rieger and
Kreager 1990). Where aggressive exotics
are present, every effort should be made
to avoid unnecessary soil disturbance or
disruption of intact native vegetation,
and newly established populations of
exotics should be eradicated.
Nonnative species such as salt cedar
(Tamarix spp.) and Russian olive
(Elaeagnus angustifolia) can outcom-
pete native plantings and negatively
affect their establishment and growth.
The likelihood of successful reestablish-
ment often increases when artificial
flows created by impoundments are al-
tered to favor native species and when
exotics such as salt cedar are removed
before revegetation is attempted (Briggs
etal. 1994).
Salt cedar is an aggressive, exotic colo-
nizer in the West due to its long period
and high rate of seed production, as well
as its ability to withstand long periods of
inundation. Salt cedar can be controlled
either by clearing with a bulldozer or by
direct application of herbicide (Sudbrock
1993); however, improper treatments
may actually increase the density of salt
cedar (Neill 1990).
Controlling exotics and weeds can be
important because of potential compe-
tition with established native vegeta-
tion, colonized vegetation, and
artificially planted vegetation in restora-
tion work. Exotics compete for mois-
ture, nutrients, sunlight, and space and
can adversely influence establishment
rates of new plantings. To improve the
effectiveness of revegetation work, ex-
otic vegetation should be cleared prior
to planting; nonnative growth must also
8-82
Chapter 8: Restoration Design
-------
be controlled after planting. General
techniques for control of exotics and
weeds are mechanical (e.g., scalping or
tilling), chemical (herbicides), and fire.
For a review of treatment methods and
equipment, see U.S. Forest Service
(1965) and Yoakum et al. (1980).
Agriculture
America's Private LandA Geography
of Hope (USDA-NRCS 1996b) chal-
lenges all of us to "regain our sense of
place and renew our commitment to
private landowners and the public."
It suggests that as we learn more about
the complexity of our environment,
harmony with ecological processes that
extend across all landscapes becomes
more of an imperative than an ideal.
Furthermore, conservation provisions
of the 1996 Farm Bill and accompany-
ing endeavors such as the National
Conservation Buffer Initiative (USDA-
NRCS 1997) offer flexibility to care for
the land as never before. The following
land use scenario attempts to express
this flexibility in the context of com-
prehensive, locally led conservation
work, including stream corridor
restoration.
This scenario offers a brief glimpse into
a hypothetical agricultural setting where
the potential results of stream corridor
restoration might begin to take form.
Computer-generated simulations are
used to graphically illustrate potential
changes brought about by restoration
work and associated comprehensive,
on-farm conservation planning. It fo-
cuses, conceptually, on vegetative clear-
ing, instream modifications, soil
exposure and compaction, irrigation
and drainage, and sediment or contami-
nants as the most disruptive activities
associated with agricultural land use.
Although an agricultural landscape
typical of the Midwest was selected
for illustrative purposes, the concepts
shown can apply in different agricul-
tural settings.
Hypothetical Existing
Conditions
Reminiscent of the highly disruptive
agricultural activities discussed in
Chapter 3, Figure 8.52 illustrates hypo-
thetical conditions that focus primarily
on production agriculture. Although
functionally isolated contour terraces
and a waterway have been installed in
the nearby cropland, the scene depicts
an ecologically deprived landscape.
Many of the potential disturbance
Figure 8.52:
Hypothetical condi-
tions. Activities caus-
ing change in this
agricultural setting.
orridor
e Clearing
annelization
oil Compaction
Soil Exposure
Drainage
Controlled Oi
Grassed Waterway
Contour Terraces
Uplands
Vegetative Clearing
Soil Compaction
Soil Exposure
Drainage
Controlled Outlets
Exotic Species
Contaminants
Landscape/
Watershed
Fragmentation
Homogenization
Contaminants
Exotic Invasion
Land Use Scenarios
8-83
-------
Figure 8.53: Hypothetical restoration response. Possible results of stream
corridor restoration are presented in this computer-altered photograph.
Introduced Vegetation Upland Corridor
and Wetlands fenceraw
. Habitat (interior/edge) Field Border
Connectivity
Width (corridor)
Windbrffilk/Sheltfrbelt-
- Upland Corridor,
Native Plant Cover
Habitat
Wetland Filter
Farmstead Management
Vegetative Buffer
Wetland Buffer (fil
Restored Wetland
Sediment Sink
Restored Wetland and
Riparian Habitat
Filter Runoff
Nutrient Management
Channel Restoration
- Re-instate Meande
Width/Depth
Aquatic Habitat
Remineant Channel Connections
Native Plant Recovery
Upland BMP's for Agriculture
Conservation Cover
Contour Farming
Field Borders
Foresttand Erosion Control
Hedgerow Planting
Nutrient Management
Pest Management
Residue Management
Strip Cropping
Tree/Shrub Planting
Water Spreading
Wildlife Upland Habitat Management
Windbreak/Shelterbelt Establishment
and Renovation
activities and subsequent changes
outlined in Chapter 3 come to mind.
Those hypothetically reflected in the
figure are highlighted in Table 8.8.
Hypothetical Restoration
Response
Previous sections of this chapter and
earlier chapters identified connectivity
and dimension (width) as important
structural attributes of stream corridors.
Nutrient and water flow, sediment trap-
ping during floods, water storage,
movement of flora and fauna, species
diversity, interior habitat conditions,
and provision of organic materials to
aquatic communities were described as
just a few of the functional conditions
affected by these structural attributes.
Continuous indigenous vegetative
cover across the widest possible stream
corridor was generally identified as the
most conducive to serving the broadest
range of functions. This discussion
went on to suggest that a long, wide
stream corridor with contiguous vegeta-
tive cover is a favored overall character-
istic. A contiguous, wide stream
corridor may be unachievable, however,
where competing land uses prevail.
Furthermore, gaps caused by distur-
bances (utility crossings, highways and
access lanes, floods, wind, fire, etc.)
are commonplace.
Restoration design should establish
functional connections within and ex-
ternal to stream corridors. Landscape
elements such as remnant patches of
riparian vegetation, prairie, or forest
exhibiting diverse or unique vegetative
communities; productive land that can
support ecological functions; reserve or
abandoned land; associated wetlands or
meadows; neighboring springs and
stream systems; ecologically innovative
residential areas; and movement corri-
dors for flora and fauna (field borders,
windbreaks, waterways, grassed terraces,
etc.) offer opportunities to establish
these connections. An edge (transition
zone) that gradually changes from one
land use into another will soften envi-
ronmental gradients and minimize
disturbance.
With these and the broad design guide-
lines presented in previous sections of
this chapter in mind, Figure 8.53 pre-
sents a conceptual computer-generated
illustration of hypothetical restoration
8-84
Chapter 8: Restoration Design
-------
Existing
Disturbance Activities
Table 8.8: Summary of prominent agriculturally
related disturbance activities and potential effects.
I
Potential Effects
Decreased landscape diversity
Point source pollution
Nonpoint source pollution
Dense compacted soil
Increased upland surface runoff
Increased sheetflow with surface erosion rill and gully flow
Increased levels of fine sediment and contaminants in stream corridor
Increased soil salinity
Increased peak flood elevation
Increased flood energy
Decreased infiltration of surface runoff
Decreased interflow and subsurface flow to and within the stream corridor
Reduced ground water recharge and aquifer volumes
Increased depth to ground water
Decreased ground water inflow to stream
Increased flow velocities
Reduced stream meander
Increased or decreased stream stability
Increased stream migration
Channel widening and downcutting
Increased stream gradient and reduced energy dissipation
Increased flow frequency
Reduced flow duration
Decreased capacity of floodplain and upland
Increased sediment and contaminants
Decreased capacity of stream
Reduced stream capacity to assimilate nutrients/pesticides
Confined stream channel with little opportunity for habitat development
Increased streambank erosion and channel scour
Increased bank failure
llfj
IE
]*JL*j[.*j[ ll"li |
_
IHH
JHHt
Jl
Loss of instream organic matter and related decomposition
Increased instream sediment, salinity, or turbidity
Increased instream nutrient enrichment, sedimentation, and contaminants
leading to eutrophication
Activity has potential for direct impact.
Activity has potential for indirect impact.
Land Use Scenarios
8-85
-------
Existing
Disturbance Activities
Table 8.8: Summary of prominent agriculturally
related disturbance activities and potential effects
(continued).
II
Potential Effects
Highly fragmented stream corridor with reduced linear distribution of habitat
and edge effect
Loss of edge and interior habitat
Decreased connectivity and dimension (width) within corridor and to associated
ecosystems
Decreased movement of flora and fauna species for seasonal migration,
dispersal repopulation
Reduced stream capacity to assimilate nutrients/pesticides
Increase of opportunistic species, predators
,
JLJLJLJ
IB
Increased exposure to solar radiation, weather, and temperature
Magnified temperature and moisture extremes in corridor
Loss of riparian vegetation
Decreased source of instream shade, detritus, food, and cover
Loss of edge diversity
Increased water temperature
Impaired aquatic habitat
HHEBHE
Reduced invertebrate population
Loss of wetland function
Reduced instream oxygen
Invasion of exotic species
Reduced gene pool
Reduced species diversity
Activity has potential for direct impact.
Activity has potential for indirect impact.
results. Table 8.9 identifies some of
the restoration measures hypothetically
implemented and their potential
effects on restoring conditions within
the stream corridor and surrounding
landscape.
Forestry
Stream corridors are a source of large
volumes of timber. Timber harvesting
and related forest management prac-
tices in riparian corridors often necessi-
tate stream corridor restoration. Forest
management may be an on-going land
use and part of the restoration effort.
Regardless, accessing and harvesting
timber affects streams in many ways
including:
Alteration of soil conditions.
Removal of the forest canopy.
Reduction in the potential supply
of large organic (woody) debris
(Beltetal. 1992).
8-86
Chapter 8: Restoration Design
-------
Restoration Measures
Table 8.9: Summary of prominent restoration
measures and potential resulting effects.
Increased landscape diversity
Increased stream order
Reduced point source pollution
Reduced nonpoint source pollution ] |«| \m\ \m\ \m\ \m\ \m\ jjij
Increased soil friability
Decreased upland surface runoff
I... . .. - I.......... I t .. I I i I I t . Ml III J I I I ' ....I I I
Decreased sheetflow, width, surface erosion, rill and gully flow
Decreased levels of fine sediment and contaminants in stream corridor
Decreased soil salinity
Decreased peak flood elevation
Decreased flood energy
Increased infiltration of surface runoff
L_ II 1 !§ ^M ^» ^M
Increased interflow and subsurface flow to and within stream corridor
Increased ground water recharge and aquifer volumes
Decreased depth to ground water
Increased ground water inflow to stream
Decreased flow velocities
Increased stream meander
Increased stream stability
Reduced channel widening and downcutting
Decreased stream gradient and increased energy dissipation
Decreased flow frequency
Increased flow duration
Increased capacity of floodplain and upland
Decreased sediment and contaminants
Increased capacity of stream
Increased stream capacity to assimilate nutrients/pesticides
Enhanced stream channel with more opportunity for habitat development
Decreased streambank erosion and channel scour
Decreased bank failure
Gain of instream organic matter and related decomposition
Decreased instream sediment, salinity, or turbidity
Measure contributes directly to resulting effect.
Measure contributes little to resulting effect.
Land Use Scenarios
8-87
-------
Restoration Measures
Table 8.9: Summary of prominent restoration measures
and potential resulting effects (continued).
Decreased instream nutrient enrichment, siltation, and contaminants
leading to eutrophication
Connected stream corridor with increased linear distribution of habitat anc
edge effect
Gain of edge and interior habitat
Increased connectivity and dimension (width) within corridor and tc
associated ecosystems
1QQQQ0QB
Increased movement of flora and fauna species for seasonal migration,
dispersal repopulation
Decrease of opportunistic species, predate
Decreased exposure to solar radiation, weather, and temperature
Decreased temperature and moisture extremes in corridor
Increased riparian vegetation
Increased source of in stream shade, detritus, food, and cover
Increase of edge diversity
Decreased water temperature
Enhanced aquatic habitat
Increased invertebrate population
Increased wetland function
Increased instream oxygen
Decrease of exotic species
Increased gene pool
Increased species diversity
Measure contributes directly to resulting effect.
Measure contributes little to resulting effect.
Forest Roads
The vast majority of the restoration de-
sign necessary following timber harvest
is usually devoted to the road system,
where the greatest alteration of soil con-
ditions has taken place. Inadequate
drainage, poor location, improperly
sized and maintained culverts, and lack
of erosion control measures on road
prisms, cut-and-fill slopes, and ditches
are problems common to a poor road
design (Stoner and McFall 1991). The
most extreme road system rehabilita-
tion requires full road closure. Full road
closure involves removal of culverts and
restoration of the streams that were
crossed. It can also involve the ripping
or tilling of road surfaces to allow plant
establishment. If natural vegetation has
not already invaded areas of exposed
soils, planting and seeding might be
necessary.
Full closure might not be a viable alter-
native if roads are needed to provide
8-88
Chapter 8: Restoration Design
-------
access for other uses. In these circum-
stances a design to restrict traffic might
be appropriate. Voluntary traffic control
usually cannot be relied on, so traffic
barriers like gates, fences, or earth
berms could be necessary. Even with
traffic restriction, roads require regular
inspection for existing or potential
maintenance needs. The best time for
inspection is during or immediately
after large storms or snowmelt episodes
so the effectiveness of the culverts and
road drainage features can be witnessed
first-hand. Design should address regu-
lar maintenance activities including
road grading, ditch cleaning, culvert
cleaning, erosion control vegetation
establishment, and vegetation manage-
ment.
Buffer Strips in Forestry
Forested buffer strips are generally more
effective in reducing sediment and
chemical loadings in the stream corri-
dor than vegetated filter strips (VFS).
However, they are susceptible to similar
problems with concentrated flows.
Buffers constructed as part of a conser-
vation system increase effectiveness.
A stiff-stemmed grass hedge could be
planted upslope of either a VFS or a
woody riparian forest buffer. The stiff-
stemmed grass hedge keeps sediment
out of the buffer and increases shallow
sheet flow through the buffer.
Most state BMPs also have special sec-
tions devoted to limitations for forest
management activities in riparian
"buffer strips" (also referred to as
Streamside Management Zones or
Streamside Protection Zones).
Budd et al. (1987) developed a proce-
dure for determining buffer widths for
streams within a single watershed in the
Pacific Northwest. They focused their
attention primarily on maintenance of
fish and wildlife habitat quality (stream
BMP Implementation and Section 319 of
the Clean Water Act
Section 319 of the Clean Water Act of 1987 required the
states to identify and submit BMPs for USEPA approval to
help control nonpoint sources of pollution. As of 1993, 41
of 50 states had EPA-approved voluntary or regulatory BMP
programs dealing with silvicultural (forest management)
activities. The state BMPs are all similar; the majority deal
with roads. Montana, for example, has a total of 55 specif-
ically addressed forest practices. Of those 55 practices, 35
deal with road planning and location, road design, road
maintenance, road drainage, road construction, and stream
crossings.
temperature, food supply, stream struc-
ture, sediment control) and found that
effective buffer widths varied with the
slope of adjacent uplands, the distribu-
tion of wetlands, soil and vegetation
characteristics, and land use. They con-
cluded that practical determinations of
stream buffer width can be made using
such analyses, but it is clear that a
generic buffer width which would pro-
vide habitat maintenance while satisfy-
ing human demands does not exist.
The determination of buffer widths
involves a broad perspective that inte-
grates ecological functions and land
use. The section on design approaches
to common effects at the beginning of
this chapter also includes some discus-
sion on stream buffer width.
Stream corridors have varied dimen-
sions, but stream buffer strips have
legal dimensions that vary by state
(Table 8.10). The buffer may be only
part of the corridor or it may be all of it.
Unlike designing stream corridors for
recreation features or grazing use, de-
signing for timber harvest and related
forest management activities is quite
Land Use Scenarios
8-89
-------
regimented by law and regulation. Spe-
cific requirements vary from state to
state; the state Forester's office or local
Extension Service can provide guidance
on regulatory issues. USDA Natural Re-
source Conservation Service offices and
Soil and Water Conservation District of-
fices also are sources of information.
Refer to Belt et al. (1992) and Welsch
(1991) for guidance on riparian buffer
strip design, function, and management.
Salo and Cundy (1987) provide infor-
mation on forestry effects on fisheries.
Grazing
The closer an ecosystem is managed to
allow for natural ecological processes to
function, the more successful a restora-
tion strategy will be. In stream corridors
that have been severely degraded by
grazing, rehabilitation should begin
with grazing management to allow for
vegetative recovery.
Vegetative recovery is often more effec-
tive than installing a structure. The veg-
etation maintains itself in perpetuity,
allows streams to function in ways that
artificial structures cannot replicate, and
provides resiliency that allows riparian
systems to withstand a variety of envi-
ronmental conditions (Elmore and
Beschta 1987)
Designs that promote vegetative recov-
ery after grazing are beneficial in a
number of ways. Woody species can
provide resistance to channel erosion
and improve channel stability so that
other species can become established.
As vegetation becomes established,
channel elevation will increase as sedi-
ment is deposited within and along the
banks of the channel (aggradation),
and water tables will rise and may reach
the root zone of plants on former ter-
races or floodplains. This aggradation of
the channel and the rising water table
Table 8.10: Buffer
strip requirements
by state.
1 State 1 Stream
1 Class
Idaho Class 1*
Class II**
Washington Type 1, 2,
and 3*
Type 4**
California Class I and
Class II*
Class III**
Oregon Class I**
I
[Buffer Strip Requirements
Width
Fixed minimum
(75 feet)
Fixed minimum
(5 feet)
Variable by
stream width
(5 to 100 feet)
None
Variable by slope
and stream class
(50 to 200 feet)
Noneb
Variable, 3 times
stream width
(25 to 100 feet)
1 Shade or Canopy
75% current shade3
None
50%, 75% if
temperature > 60°F
None
50% overstory and/or
understory; dependent
on slope and stream class
50% understory6
50% existing canopy,
75% existing shade
1 Leave Trees
Yes, number per 1000 feet,
dependent on stream
widthb
None
Yes, number per 1000 feet,
dependent on stream width
and bed material
25 per 1000 feet,
6 inches diameter
Yes; number to be
determined by canopy
density
None6
Yes; number per 1000 feet
and basal area per 1000
feet by stream width
Class II special None'
protection**
75% existing shade
None
* Human water supply or fisheries use.
** Streams capable of sediment transport (CA) or other influences (ID and WA) or significant impact (OR) on downstream waters.
a In ID, the shade requirement is designed to maintain stream temperatures.
b In ID, the leave tree requirement is designed to provide for recruitment of large woody debris.
c May range as high as 300 feet for some types of timber harvest.
d To be determined by field inspection.
e Residual vegetation must be sufficient to prevent degradation of downstream beneficial uses.
f In eastern OR, operators are required to "leave stabilization strips of undergrowth... sufficient to prevent washing of sediment into
Class I streams below."
8-90
Chapter 8: Restoration Design
-------
Pacific Northwest Floods of 1996
Floods, Landslides, and Forest Management
'The Rest of The Story'
Warm winds, intense rainfall, and rapid snowmelt
during the winter of 1995-96 and again in the
winter of 1996-97 caused major flooding, land-
slides, and related damage throughout the Pacific
Northwest (Figure 8.54). Such flooding had not
been seen for more than 30 years in hard-hit
areas. Damage to roads, campgrounds, trails,
watersheds, and aquatic resources was wide-
spread on National Forest Service lands. These
events offered a unique opportunity to investi-
gate the effects of severe weather, examine the
influence and effectiveness of various forest man-
agement techniques, and implement a repair
strategy consistent with ecosystem management
principles.
The road network in the National Forests was
heavily damaged during the floods. Decisions
about the need to replace roads are based on
long-term access and travel requirements.
Relocation of roads to areas outside floodplains is
a measure being taken. Examination of road
crossings at streams concluded with design rec-
ommendations to keep the water moving, align
culverts horizontally and longitudinally with the
stream channel, and minimize changes in stream
channel cross section at inlet basins to prevent
debris plugs.
Many river systems were also damaged. In some
systems, however, stable, well-vegetated slopes
and streambanks combined with fully functioning
floodplains buffered the effects of the floods.
Restoration efforts will focus on aiding natural
processes in these systems. Streambank stabiliza-
tion and riparian plantings will be commonly
used. Examination of instream structure durability
concluded that structures are more likely to
remain in place if they are in fourth-order or
smaller streams and are situated in a manner that
maintains a connection between the structure
and the streambank. They will be most durable
in watersheds with low landslide/debris torrent
frequency.
Figure 8.54: 1996 Landslides, (a) April landslide:
debris took out the track into the Greenwater River
and (b) July landslide: debris took out the road and
deposited debris into the river.
Land Use Scenarios
8-91
-------
allow more water to be stored during
wet seasons, thereby prolonging flow
even during periods of drought (Elmore
and Beschta 1987).
Kauffman et al. (1993) observed that
fencing livestock out of the riparian
zone is the only grazing strategy that
consistently results in the greatest rate
of vegetative recovery and the greatest
improvement in riparian function.
However, fencing is very expensive, re-
quires considerable maintenance, and
can limit wildlife accessa negative
impact on habitat or conduit functions.
Some specialized grazing strategies hold
promise for rehabilitating less severely
impacted riparian and wetland areas
without excluding livestock for long pe-
riods of time. The efficiency of a num-
ber of grazing strategies with respect to
fishery needs are summarized in
Tables 8.11 and 8.12 (from Platts
1989). They summarize the influence of
grazing systems and stream system char-
acteristics on vegetation response, pri-
marily from a western semiarid
perspective. Some general design rec-
ommendations for selecting a strategy
include the following (Elmore and
Kauffmann 1994):
Each strategy must be tailored to a
particular stream or stream reach.
Management objectives and compo-
nents of the ecosystem that are of
critical value must be identified (i.e.,
woody species recovery, streambank
restoration, increased habitat diversi-
ty, etc.). Other information that
should be identified includes present
vegetation, potential of the site for
recovery, the desired future condi-
tion, and the current factors causing
habitat degradation or limiting its
recovery.
The relationships between ecological
processes that must function for
riparian recovery should be
described. Factors affecting present
condition (i.e., management stress vs.
natural stress) and conditions
required for the stream to resume
natural functions need to be
assessed. Anthropogenic factors caus-
ing stream degradation must be iden-
tified and changed.
Design and implementation should
be driven by attainable goals, objec-
tives, and management activities that
will achieve the desired structure and
functions.
Implementation should include a
monitoring plan that will evaluate
management, allowing for correc-
tions or modifications as necessary,
and a strong compliance and use
supervision program.
The main consideration for selecting a
grazing system is to have an adequate
vegetative growing season between the
period of grazing and timing of high-
energy runoff. It is impossible to pro-
vide a cookie-cutter grazing strategy for
every stream corridor; designs have to
be determined on the ground, stream
by stream, manager by manager. Simply
decreasing the number of livestock is
not a solution to degraded riparian con-
ditions; rather, restoring these degraded
areas requires fundamental changes in
the ways that livestock are grazed
(Chaneyetal. 1990).
Clearly, the continued use of grazing
systems that do not include the func-
tional requirements of riparian vegeta-
tion communities will only perpetuate
riparian problems (Elmore and Beschta
1987). Kinch (1989) and Clary and
Webster (1989) provide greater detail
on riparian grazing management and
designing alternative grazing strategies.
Chaney et al. (1990) present photo his-
tories of a number of interesting graz-
ing restoration case studies, and of the
8-92
Chapter 8: Restoration Design
-------
Table 8.11: Evaluation and rating of grazing strategies.
Strategy3
Continuous season-long
(cattle)
Holding (sheep or cattle)
Short duration-high
intensity (cattle)
Three herd-four pasture
(cattle)
Holistic (cattle or sheep)
Deferred (cattle)
Seasonal suitability
(cattle)
Deferred-rotation (cattle)
Stuttered deferred-
rotation (cattle)
Winter (sheep or cattle)
Rest-rotation (cattle)
Double rest-rotation
(cattle)
Seasonal riparian
preference
(cattle or sheep)
Riparian pasture
(cattle or sheep)
Corridor fencing
(cattle or sheep)
Rest-rotation with
seasonal preference
(sheep)
Rest or closure
(cattle or sheep)
Level to Which
Riparian
Vegetation is
Commonly Used
Heavy
Heavy
Heavy
Heavy to
moderate
Heavy to light
Moderate to
heavy
Heavy
Heavy to
moderate
Heavy to
moderate
Moderate to
heavy
Heavy to
moderate
Moderate
Moderate to
light
As prescribed
None
Light
None
Control of
Animal
Distribution
(Allotment)
Poor
Excellent
Excellent
Good
Good
Fair
Good
Good
Good
Fair
Good
Good
Good
Good
Excellent
Good
Excellent
Streambank
Stability
Poor
Poor
Poor
Poor
Poor to
good
Poor
Poor
Fair
Fair
Good
Fair to
good
Good
Good
Good
Good to
excellent
Good to
excellent
Excellent
Brushy
Species
Condition
Poor
Poor
Poor
Poor
Poor
Poor
Poor
Fair
Fair
Fair
Fair
Fair
Good
Good
Good to
excellent
Good to
excellent
Excellent
Seasonal
Plant
Regrowth
Poor
Fair
Poor
Poor
Good
Fair
Fair
Fair
Fair
Fair to
good
Fair to
good
good
Fair
Good
Good
Good
Excellent
I Stream
I Riparian
I Rehabilitation
I Potential
Poor
Poor
Poor
Poor
Poor to
excellent
Fair
Fair
Fair
Fair
Good
Fair
Good
Fair
Good
Excellent
Excellent
Excellent
Fishery
Needs
Ratingb
1
1
1
2
2-9
3
3
4
4
5
5
6
6
8
9
9
10
a Jacoby (1989) and Platts (1989) define these management strategies
b Rating scale based on 1 (poorly compatible) to 10 (highly compatible with fishery needs)
Land Use Scenarios
8-93
-------
Table 8.12: Generalized relationships between grazing systems, stream system characteristics, and riparian vegetation
response.
1 Grazing
System
No grazing
Winter or
dormant
season
Early growing
season
Deferred or
late season
Three-pasture
rest rotation
Deferred
rotation
Early rotation
Rotation
Season-long
Spring and fall
Spring and
summer
1 Steep
Low Sediment
Load
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
+
+
0
~^T~
+
0
+
+
0
_
+
Oto-
_
+
Oto-
_
+
Oto-
+
+
Oto-
_
+
Oto-
_
-
Oto-
_
_
Oto-
_
-
Oto-
1 Steep
High Sediment
Load
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
+
+
Oto +
T~
+
Oto +
+
+
Oto +
_
+
Oto-
_
+
Oto-
_
+
Oto-
+
+
Oto +
_
+
Oto-
_
-
Oto-
_
-
Oto-
_
-
Oto-
1 Moderate
Low Sediment
Load
Shrubs +
Herbs +
Banks 0
Shrubs +
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs
Herbs +
Banks 0 to +
Shrubs
Herbs +
Banks 0 to +
Shrubs
Herbs +
Banks +toO
Shrubs +
Herbs +
Banks + to 0
Shrubs
Herbs +
Banks Oto +
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Moderate
High Sediment
Load
Shrubs +
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks -toO
Flat
Low Sediment
Load
Shrubs +
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks -toO
Shrubs
Herbs
Banks -toO
Flat
High Sediment
Load
Shrubs +
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs +
Herbs +
Banks +
Shrubs
Herbs +
Banks +
Shrubs
Herbs
Banks
Shrubs
Herbs
Banks Oto +
Shrubs
Herbs
Banks 0 to +
Note: - = decrease; + = increase; 0 = no change. Stream gradient: 0 to 2% = flat; 2 to 4% = moderate; > 4% = steep. Banks refers to bank stability.
8-94
Chapter 8: Restoration Design
-------
CASESUI^Y Oven Run, Pennsyl
vania
The effects of abandoned mines draining
into the surrounding lands cause dramatic
changes in the area (Figure 8.55(a)). Runoff with
high levels of minerals and acidity can denude
the ground of vegetation, expose the soil, and
allow erosion with the sediment further stressing
streams and wetland. Any efforts to restore
streams in this environment must deal with the
problem if any success is to be likely.
The Natural Resources Conservation Service, for-
merly known as the Soil Conservation Service,
has been working on the Oven Run project
along with the Stonycreek Conemaugh River
Improvement (SCRIP) to improve water quality in
a 4-mile reach above the Borough of Hooversville.
SCRIP is a group of local and state government
as well as hundreds of individuals interested in
improving the water quality in an area on
Pennsylvania's Degraded Watersheds list.
The initial goal of improving water quality result-
ed in improving habitat and aesthetic qualities.
The water coming into Hooversville had higher-
than-desired levels of iron, manganese, alu-
minum, sulfate, and acidity. Six former strip
mines, which had a range of problems, were
identified. They included deep mine openings
that have large flows of acid mine drainage, acid
mine seepage into streams, eroding spoil areas,
areas of ponded water that infiltrate into ground
water (adding to the acid mine drainage), and
areas downhill of seepage and deep mine
drainage that are denuded and eroding.
Control efforts included grading and vegetating
the abandoned mine to reduce infiltration
through acid-bearing layers and reduce erosion
and sedimentation, surface water controls to
carry water around the sites to safer outlets, and
treating discharge flow with anoxic limestone
drains and chambered passive wetland treatments
(Figure 8.55(b)). Additionally, 1,000 feet of trees
were planted along one of the site streams to
shade the Stoneycreek River. Average annual
costs for the six sites were estimated to be
$503,000 compared to average annual benefits
of $513,000.
The sites are being monitored on a monthly
basis, and 4 years after work was begun the
treatments have had a measurable success. The
acid influent has been neutralized, and the efflu-
ent is now a net alkaline. Iron, aluminum, and
manganese levels have been reduced, with iron
now at average levels of 0.5 mg/L from average
levels of 35 mg/L.
Figure 8.55: Stream corridor (a) before and (b) after
restoration.
Land Use Scenarios
8-95
-------
short-term results of some of the avail-
able grazing strategies.
Mining
Post-mining reclamation of stream cor-
ridors must begin with restoration of a
properly functioning channel. Because
many of the geologic and geomorphic
controls associated with the pre-distur-
bance channel may have been obliter-
ated by mining operations, design of
the post-mining channel often requires
approaches other than mimicking the
pre-disturbance condition. Channel
alignment, slope, and size may be de-
termined on the basis of empirical rela-
tions developed from other streams in
the same hydrologic and physiographic
settings (e.g., Rechard and Schaefer
1984, Rosgen 1996). Others (e.g., Has-
further 1985) have used a combination
of empirical and theoretical approaches
for design of reclaimed channels. Total
reconstruction of stream channels is
treated at length in Section 8.E. Other
sections of the chapter address stabiliza-
tion of streambanks, revegetation of
floodplains and terraces, and restora-
tion of aquatic and terrestrial habitats.
Additional guidance is available in In-
terfluve, Inc. (1991).
Surface mining is usually associated
with large-scale disturbances in the con-
tributing watershed, therefore, a rigor-
ous hydrological analysis of pre- and
post-mining conditions is critical for
stream corridor restoration of disturbed
systems. The hydrologic analysis should
include a frequency analysis of extreme
high- and low-flow events to assess
channel performance in the post-
mining landscape.
Hydrologic modeling may be required
to generate runoff hydrographs for the
post-mining channel because watershed
geology, soils, vegetation, and topogra-
phy may be completely altered by min-
ing operations. Thus, channel design
and stability assessments will be based
on modeled runoff rates reflecting ex-
pected watershed conditions. The hy-
drologic analysis for post-mining
restoration should also address sedi-
ment production from the reclaimed
landscape. Sediment budgets (see Chap-
ter 7) will be needed for both the pe-
riod of vegetation establishment and
the final revegetated condition.
The hydrologic analyses will provide
restoration practitioners with the flow
and sediment characteristics needed for
restoration design. The analyses may
also indicate a need for at least tempo-
rary runoff detention and sediment re-
tention during the period of vegetation
establishment. However, the post-min-
ing channel should be designed for
long-term equilibrium with the fully re-
claimed landscape.
Water quality issues (e.g., acid mine
drainage) often control the feasibility of
stream restoration in mined areas and
should be considered in design.
Recreation
Both concentrated and dispersed recre-
ational use of stream corridors can
cause damage and ecological change.
Ecological damage primarily results
from the need for access for the recre-
ational user. A trail often will develop
along the shortest or easiest route to
the point of access on the stream.
Additional resource damage may be a
function of the mode of access to the
stream: motorcycles and horses cause
far more damage to vegetation and
trails than do pedestrians. Control of
streambank access in developed recre-
ation sites must be part of a restora-
tion design. On undeveloped or
unmanaged sites, such control is
more difficult but still very necessary
(Figure 8.56).
8-96
Chapter 8: Restoration Design
-------
Rehabilitation of severely degraded
recreation areas may require at least
temporary use restrictions. Even actively
eroding trails, camp and picnic sites,
and stream access points can be stabi-
lized through temporary site closure
and combinations of soil and vegeta-
tion restoration (Wenger 1984, Marion
and Merriam 1985, Hammitt and Cole
1987). Closure will not provide a long-
term solution if access is restored with-
out addressing the cause of the original
problem. Rather, new trails and recre-
ation sites should be located and con-
structed based on an understanding of
vegetation capabilities, soil limitations,
and other physical site characteristics.
Basically, the keys to a successful design
are:
Initially locating or moving use to
the most damage-resistant sites.
Influencing visitor use.
Hardening use areas to make them
more resistant.
Rehabilitating closed sites.
Urbanization
Few land uses have the capacity to alter
water and sediment yield from a
drainage as much as the conversion of
a watershed from rural to urban condi-
tions; thus, few land uses have greater
potential to affect the natural environ-
ment of a stream corridor.
As a first step in hydrologic analyses,
designers should characterize the nature
of existing hydrologic response and the
likelihood for future shifts in water and
sediment yield. Initially, construction
activities create excess sediment that can
be deposited in downstream channels
and floodplains. As impervious cover
increases, peak flows increase. Water be-
comes cleaner as more area is covered
with landscaping or impervious mater-
ial. The increased flows and cleaner
Figure 8.56: Controlled access. Control of
streambank access is an important part
of the restoration design.
Source: J. McShane.
water enlarge channels, which increases
sediment loads downstream.
Determine if the watershed is (a) fully
urbanized, (b) undergoing a new phase
of urbanization, or (c) is in the begin-
ning stages of urbanization (Riley,
1998).
An increase in the amount of impervi-
ous cover in a watershed leads to in-
creased peak flows and resulting
channel enlargement (Figure 8.57).
Research has shown that impervious
cover of as little as 10 to 15 percent of
a watershed can have significant adverse
effects on channel conditions (Schueler
1996). Magnitudes of channel-forming
or bankfull flood events (typically 1-
to 3-year recurrence intervals) are in-
creased significantly, and flood events
that previously occurred once every
year or two may occur as often as one
or two times a month.
Enlargement of streams with subse-
quent increases in downstream sedi-
ment loads in urbanized watersheds
should be expected and accommodated
in the design of restoration treatments.
Land Use Scenarios
8-97
-------
Figure 8.57: Storm water flow on a paved
surface. Impervious surfaces increase peak
flows and can result in channel enlargement.
Source: M. Corrigan.
Procedures for estimating peak dis-
charges are described in Chapter 7, and
effects of urbanization on magnitude of
peak flows must be incorporated into
the analysis. Sauer et al. (1983) investi-
gated the effect of urbanization on peak
flows by analyzing 199 urban water-
sheds in 56 cities and 31 states. The ob-
jective of the analysis was to determine
the increase in peak discharges due to
urbanization and to develop regression
equations for estimating design floods,
such as the 100-year or 1 percent
chance annual flood, for ungauged
urban watersheds. Sauer et al. (1983)
developed regression equations based
on watershed, climatic, and urban char-
acteristics that can be used to estimate
the 2, 5, 10, 25, 50, 100, and 500-year
urban annual peak discharges for un-
gauged urban watersheds. The equation
for the 100-year flood in cubic feet per
second (UQ100) is provided as an ex-
ample:
UQ100 = 2.50 A" SL15 (RI2+3)126
(ST+8) 52 (13-BDF) 28 IA06 RQ10063
where the explanatory variables are
drainage area in square miles (A), chan-
nel slope in feet per mile (SL), the 2-
year, 2-hour rainfall in inches (RI2),
basin storage in percent (ST), basin
development factor (BDF), which is a
measure of the extent of development
of the drainage system (dimensionless,
ranging from 0 to 12), percent impervi-
ous area (IA), and the equivalent rural
peak discharge in cubic feet per second
(RQ100) in the example equation
above.
Sauer et al. (1983) provide the allow-
able range for each variable. The two
indices of urbanization in the equation
are BDF and IA. They can be used to
adjust the rural peak discharge RQ100
(either estimated or observed) to urban
conditions.
Sauer et al. (1983) provide equations
like the one above and graphs that re-
late the ratio of the urban to rural peak
discharge (UQx/RQx) for recurrence in-
tervals x = 2, 10, and 100 years. The 2-
year peak ratio varies from 1.3 to 4.3,
depending on the values of BDF and IA;
the 10-year ratio varies from 1.2 to 3.1;
and the 100-year ratio varies from 1.1
to 2.6. These ratios indicate that urban-
ization generally has a lesser effect on
higher-recurrence-interval floods be-
cause watershed soils are more satu-
rated and floodplain storage more fully
depleted in large floods, even in the
rural condition.
More sophisticated hydrologic analyses
than the above are often used, includ-
ing use of computer models, regional
regression equations, and statistical
analyses of gauge data. Hydrologic
models, such as HEC-1 orTR-20, are
often already developed for some urban
watersheds.
Once the flood characteristics of the
stream are adjusted for urbanization,
new equilibrium channel dimensions
8-98
Chapter 8: Restoration Design
-------
can be estimated from hydraulic geom-
etry relationships developed using data
from stable, alluvial channels in similar
(soils, slope, degree of urbanization)
watersheds, or other analytical ap-
proaches. Additional guidance for de-
sign of restored channels is provided
earlier in this chapter in the section on
channel reconstruction.
Changes in flooding caused by urban-
ization of a watershed can be mitigated
during urban planning through prac-
tices designed to control storm runoff.
These practices emphasize the use of
vegetation and biotechnical methods, as
well as structural methods, to maintain
or restore water quality and dampen
peak runoff rates. Strategies for control-
ling runoff include the following:
Increasing infiltration of rainfall and
streamflow to reduce runoff and to
remove pollutants.
Increasing surface and subsurface
storage to reduce peak flows and
induce sediment deposition.
Filtration and biological treatment of
suspended and soluble pollutants
(i.e., constructed wetlands).
Establishment arid/or enhancement
of forested riparian buffers.
Management of drainage from the
transportation network.
Introduction of trees, shrubs, etc., for
various restoration purposes.
In addition to changes in water yield,
urbanization of a watershed frequently
generates changes in its sediment yield.
In humid climates, vegetative cover
prior to urbanization often is adequate
to protect soil resources and minimize
natural erosion, and the combination
of impervious area and vegetation of a
fully urban watershed might be ade-
quate to minimize sediment yield. Dur-
ing the period of urbanization,
however, sediment yields increase sig-
nificantly as vegetation is cleared and
bare soil is exposed during the con-
struction process. In more arid climates,
sediment yield from an urban water-
shed may actually be lower than the
yield from a rural watershed due to the
increased impervious area and vegeta-
tion associated with landscaping, but
the period of urbanization (i.e., con-
struction) is still the time of greatest
sediment production.
The effect of urbanization on sediment
discharge is illustrated in Figure 8.58,
which contains data from nine sub-
basins in a 32-square-mile area in the
Rock Creek and Anacostia River Basins
north of Washington, DC (Yorke and
Herb 1978). During the period of data
collection (1963-74), three subbasins
remained virtually rural while the oth-
ers underwent urban development. In
1974, urban land represented from 0 to
60 percent of land use in the nine sub-
basins. These data were used to develop
a relation between suspended sediment
yield and the percentage of land under
construction. This relation indicated
that suspended sediment yield in-
creased about 3.5 times for watersheds
with 10 percent of the land area under
construction. However, suspended-sedi-
ment yields for watersheds where sedi-
ment controls (primarily sediment
basins) were employed for 50 percent
of the construction area were only
about one-third of these for areas with-
out controls. The effect of controls is
seen in the figure. The three curves pre-
sent growing season data for three peri-
ods of increasing sediment control:
1963-67, when no controls were used
on construction sites; 1968-71, when
controls were mandatory; and 1972-74,
when controls were mandatory and
subject to inspection by county officials.
It further illustrates that storm runoff is
not the only factor affecting storm sedi-
Land Use Scenarios
8-99
-------
10,000
5000
o 1000
500
01
01
H
1/1
S 100
in
50
10
1963-67
1968-71
1972-74
00
O
I
10
50 100
Storm Runoff (cfs-days)
500 1000
Figure 8.58: Sediment-transport curves for
growing season storms. The effect of urban-
ization on sediment discharge is illustrated
from data collected in a 32-square-mile area.
ment discharge as evidenced by the sig-
nificant scatter about each relation.
In addition to sediment basins, man-
agement practices for erosion and sedi-
ment control focus on the following
objectives:
Stabilizing critical areas along and
on highways, roads, and streets.
Siting and placement of sediment
migration barriers.
Design and location of measures to
divert or exclude flow from sensitive
areas.
Protection of waterways and outlets.
Stream and corridor protection and
enhancement.
All of these objectives emphasize the
use of vegetation for sediment control.
Additional information on BMPs for
controlling runoff and sediment in
urban watersheds can be found in the
Techniques Appendix.
In theory, a local watershed manage-
ment plan might be the best tool to
protect a stream corridor from the cu-
mulative impact of urban development;
however, in practice, few such plans
have realized this goal (Schueler 1996).
To succeed, such plans must address the
amount of bare ground exposed during
construction and the amount of imper-
vious area that will exist during and
after development of the watershed.
More importantly, success will depend
on using the watershed plan to guide
development decisions, and not merely
archiving it as a one-time study whose
recommendations were read once but
never implemented (Schueler 1996).
Key Tools of Urban Stream
Restoration Design
Restoration design for streams degraded
by prior urbanization must consider
pre-existing controls and their effects on
restoration objectives. Seven restoration
tools can be applied to help restore
urban streams. (Schereler,1996) These
tools are intended to compensate for
stream functions and processes that
have been diminished or degraded by
prior watershed urbanization. The best
results are usually obtained when the
following tools are applied together.
Tool 1. Partially restore the predevelopment
hydrological regime. The primary objec-
tive is to reduce the frequency of bank-
full flows in the contributing watershed.
This is often done by constructing up-
stream storm water retrofit ponds that
capture and detain increased storm
8-100
Chapter 8: Restoration Design
-------
water runoff for up to 24 hours before
release (i.e., extended detention). A
common design storm for extended de-
tention is the one-year, 24 hour storm
event. Storm water retrofit ponds are
often critical in the restoration of small
and midsized streams, but may be im-
practical in larger streams and rivers.
Tool 2. Reduce urban pollutant pulses.
A second need in urban stream restora-
tion is to reduce concentrations of nutri-
ents, bacteria and toxics in the stream,
as well as trapping excess sediment
loads. Generally, three tools can be ap-
plied to reduce pollutant inputs to an
urban stream: storm water retrofit
ponds or wetlands, watershed pollution
prevention programs, and the elimina-
tion of illicit or illegal sanitary connec-
tions to the storm sewer network
Tool 3. Stabilize channel morphology. Over
time, urban stream channels enlarge
their dimensions, and are subject to
severe bank and bed erosion. Therefore,
it is important to stabilize the channel,
and if possible, restore equilibrium
channel geometry. In addition, it is also
useful to provide undercuts or overhead
cover to improve fish habitat. Depend-
ing on the stream order, watershed im-
pervious cover and the height and angle
of eroded banks, a series of different
tools can be applied to stabilize the
channel, and prevent further erosion.
Bank stabilization measures include
imbricated rip-rap, brush bundles, soil
bioengineering methods such as willow
stakes and bio-logs, lunker structures
and rootwads. Grade stabilization mea-
sures are discussed earlier in this chap-
ter and in Appendix A.
Tool 4. Restore Instream habitat structure.
Most urban streams have poor instream
habitat structure, often typified by in-
distinct and shallow low flow channels
within a much larger and unstable
storm channel. The goal is to restore
instream habitat structure that has
been blown out by erosive floods. Key
restoration elements include the cre-
ation of pools and riffles, confinement
and deepening of the low flow chan-
nels, and the provision of greater struc-
tural complexity across the streambed.
Typical tools include the installation of
log checkdams, stone wing deflectors
and boulder clusters along the stream
channel.
Tool 5. Reestablish Riparian Cover. Ripar-
ian cover is an essential component of
the urban stream ecosystem. Riparian
cover stabilizes banks, provides large
woody debris and detritus, and shades
the stream. Therefore, the fifth tool in-
volves reestablishing the riparian cover
plant community along the stream net-
work. This can entail active reforesta-
tion of native species, removal of exotic
species, or changes in mowing opera-
tions to allow gradual succession. It is
often essential that the riparian corridor
be protected by a wide urban stream
buffer.
Tool 6. Protect critical stream substrates.
A stable, well sorted streambed is often
a critical requirement for fish spawning
and secondary production by aquatic
insects. The bed of urban streams, how-
ever, is often highly unstable and
clogged by fine sediment deposits. It is
often necessary to apply tools to restore
the quality of stream substrates at
points along the stream channel. Often,
the energy of urban storm water can be
used to create cleaner substrates
through the use of tools such as double
wing deflectors and flow concentrators.
If thick deposits of sediment have accu-
mulated on the bed, mechanical sedi-
ment removal may be needed.
Tool 7. Allow for recolonization of the
stream community. It may be difficult to
reestablish the fish community in an
urban stream if downstream fish barri-
Land Use Scenarios
8-101
-------
ers prevent natural recolonization.
Thus, the last urban stream restoration
tool involves the judgment of a fishery
biologist to determine if downstream
fish barriers exist, whether they can be
removed, or whether selective stocking
of native fish are needed to recolonize
the stream reach.
8-102 Chapter 8: Restoration Design
-------
Restoration
Implementation,**
Monitoring, and
Management
:'
-------
9.A Restoration Implementation
What are passive forms of restoration and how are they "implemented" ?
What happens after the decision is made to proceed with an active rather than a passive
restoration approach?
What type of activities are involved when installing restoration measures?
How can impact on the stream channel and corridor be minimized when installing resto-
ration measures (e.g, water quality, air quality, cultural resources, noise)?
What types of equipment are needed for installing restoration measures?
What are some important considerations regarding construction activities in the
stream corridor?
How do you inspect and evaluate the quality and impact of construction activities in the
stream corridor?
What types of maintenance measures are necessary to ensure the ongoing success of
a restoration?
9.B Monitoring Techniques Appropriate for Evaluating Restoration
What methods are available for monitoring biological attributes of streams?
What can assessment of biological attributes tell you about the status of the
stream restoration?
What physical parameters should be included in a monitoring management plan?
How are the physical aspects of the stream corridor evaluated?
How is a restoration monitoring plan developed, and what issues should be addressed in
the plan?
What are the sampling plan design issues that must be addressed to adequately detect
trends in stream corridor conditions?
How do you ensure that the monitoring information is properly collected, analyzed, and
assessed (i.e., quality assurance plans)?
9.C Restoration Management
What are important management priorities with ongoing activities and resource uses
within the stream corridor?
What are some management decisions that can be made to support stream restoration?
What are some example impacts and management options with various types of resource
use within the stream corridor (e.g., forest management, grazing, mining, fish and wild-
life, urbanization)?
When is restoration complete?
-------
Restoration
Implementation!
Monitoring, and
Management
9.A Restoration Implementation
9.B Monitoring Techniques Appropriate for
Evaluating Restoration
9.C Restoration Management
Completion of the restoration design
marks the beginning of several impor-
tant tasks for the stream restoration prac-
titioner. Emphasis must now be placed on
prescribing or implementing restoration
measures, monitoring and assessing the
effectiveness of the restoration, and man-
aging the design to achieve the desired
stream corridor conditions (Figure 9.1).
Implementation, management, and moni-
toring/evaluation may proceed as part of
a larger setting, or they may be considered
components of a corridor-specific restora-
tion effort. In either case, they require
full planning and commitment before
the restoration plan is implemented. The
technical complexity of a project must be
determined by the restoration practitioner
based on available resources, technology,
and what is necessary to achieve restora-
tion goals. There must be reasonable
assurance that there
will be continuing
access for ongoing
inspection, mainte-
Figure 9.1: A restored stream.
Stream corridor restoration
measures must be properly
installed, monitored, and man-
aged to be successful.
-------
nance, emergency repairs, manage-
ment, and monitoring activities as
well. All cooperators should be
aware that implementation, moni-
toring, and management might re-
quire unanticipated work, and that
plans and objectives might change
over time as knowledge improves
or as changes occur.
This chapter builds on the discus-
sion of restoration implementation,
monitoring, evaluation, and adap-
tive management presented in
Chapter 6. Specifically, it moves be-
yond the planning components as-
sociated with these key restoration
activities and discusses some of the
technical issues and elements that
restoration practitioners must con-
sider when installing, monitoring,
and managing stream corridor
restoration measures.
The discussion that follows is di-
vided into three major sections.
Section 9.A: Restoration
Implementation
This first section describes the im-
plementation of restoration mea-
sures beyond just removing
disturbance factors and taking
other passive approaches that allow
the stream corridor to restore itself
over time.
Technical considerations relating to
site preparation, site clearing, con-
struction, inspection, and mainte-
nance are discussed in this section.
Section 9.6: Monitoring Techniques
Appropriate for Evaluating
Restoration
The purpose of restoration monitor-
ing is to gather data that will help
to determine the success of the
restoration effort. This section pre-
sents some of the monitoring tech-
niques appropriate for evaluating
restoration.
Section 9.C: Restoration
Management
Management of the restoration be-
gins with the implementation of
the plan. The "adaptive manage-
ment" approach was presented in
Chapter 6 as an important part of
the planning process. It provides
the flexibility to detect when
changes are needed to achieve suc-
cess and to be able to make the
necessary midcourse, short-term
corrections.
Ideally, the long-term management
of a successful restoration will in-
volve only periodic monitoring to
check that the system is sustaining
itself through natural processes.
However, this is rarely the case for
stream corridors in human-inhab-
ited landscapes.
New crops, markets, and govern-
ment programs can rapidly and sig-
nificantly alter the physical,
chemical, and biological character-
istics of stream corridors and their
watersheds, destroying restoration
efforts. Conversion of rural lands
9-2
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
and wildlands to urban uses and
exploitation of natural resources
can change the landscape and
cause natural processes to become
unbalanced, leaving the stream cor-
ridor with no way to sustain itself.
Additionally, natural imbalances can
occur due to local and regional cli-
matic changes, predation, disease,
fire, genetic changes, and catastro-
phes like earthquakes, hurricanes,
tornadoes, volcanic eruptions, land-
slides, and floods. Long-term man-
agement of the restored stream
corridor will therefore require vigi-
lance, anticipation, and reaction to
future changes.
9.A Restoration Implementation
Implementation of stream corridor
restoration must be preceded by careful
planning. Such planning should in-
clude the following (at a minimum):
Determining a schedule.
Obtaining necessary permits.
Conducting preimplementation
meetings.
Informing and involving property
owners.
Securing site access and easements.
Locating existing utilities.
Confirming sources of materials and
ensuring standards of materials.
The careful execution of each planning
step will help ensure the success of the
restoration implementation. Full
restoration implementation, however,
involves several actions that require
careful execution as well as the coopera-
tion of several participants. See Chap-
ters 4 and 5 for specific guidance on
planning a stream corridor initiative.
Site Preparation
Site preparation is the first step in the
implementation of restoration mea-
sures. Preparing the site requires that
the following actions be taken.
Delineating Work Zones
The area in which restoration occurs is
defined by many disparate factors. This
area is determined most fundamentally
by the features of the landscape that
must be affected to achieve restoration
goals. Boundaries of property owner-
ship, restrictions imposed by permit re-
quirements, and natural or cultural
features that might have special signifi-
cance can also determine the work zone.
A heavy-equipment operator or crew
supervisor cannot be expected to be
aware of the multiple requirements that
govern where work can occur. Thus,
delineation of those zones in the field
Major Elements of
Restoration Implementation
Review of Plans
m Site Preparation
m Site Clearing
m Installation and Construction
m Site Reclamation/Cleanup
Inspection
m Maintenance
Restoration Implementation
9-3
-------
should be the first activity conducted
on the site. The zones should be
marked by visible stakes and more
preferably by temporary fencing (usu-
ally a bright-colored sturdy plastic net-
ting). This delineation should conform
to any special restrictions noted or tem-
porary stakes placed during the precon-
struction meeting between the project
manager and field inspector.
Preparing Access and Staging
Areas
A site is often accessed from a public
road in an upland portion of the site.
Ideally, for convenience, a staging area
for crew, equipment, and materials can
be located near an access road close to
the restoration site but out of the
stream corridor and away from wet-
lands or areas with highly erodible
soils. The staging area should also be
out of view from public thoroughfares,
if possible, to increase security.
Although property ownership, topogra-
phy, and preexisting roads make access
to every site unique, several principles
should guide design, placement, and
construction of site access:
Avoid any sensitive wildlife habitat
or plant areas or threatened and
endangered species and their desig-
nated critical habitat.
Avoid crossing the stream if at all
possible; where crossing is unavoid-
able, a bridge is almost mandatory.
Minimize slope disturbance since
effective erosion control is difficult
on a sloped roadway that will be
heavily used.
Construct roadways with low gradi-
ents; ensure that storm water runoff
drains to outlets; install an adequate
roadbed; and, if possible, set up a
truck-washing station at the entrance
of the construction site to reduce off-
site transport of mud and sediment
by vehicles.
In the event of damage to any private
or public access roads used to trans-
port equipment or heavy materials to
and from the site, those responsible
should be identified and appropriate
repairs should be made.
Taking Precautions to Minimize
Disturbance
Every effort should be made to mini-
mize and, where possible, avoid site
disturbance. Emphasis should be placed
on addressing protection of existing
vegetation and sensitive habitat, erosion
and sediment control, protecting air
and water quality, protecting cultural re-
sources, minimizing noise, and provid-
ing for solid waste disposal and
worksite sanitation.
Protection of Existing Vegetation and
Sensitive Habitat
Fencing can be an effective way to en-
sure protection of areas within the con-
struction site that are to remain
undisturbed (e.g., vegetation designated
to be preserved, sensitive terrestrial
habitat, or sensitive wetland habitat).
As in delineating work zones, fencing
should be placed around all protected
areas during initial site preparation,
even before the access road is fully con-
structed, if possible, but certainly before
wholesale earthmoving begins. Fencing
material should be easy to see, and
areas should be labeled as protection
areas. Caution should always be exer-
cised when grading is planned adjacent
to a protected area.
Erosion
Many well-established principles of ef-
fective erosion and sediment control
can be readily applied to stream corri-
dor restoration (Goldman et al. 1986).
Every effort should be made to prevent
9-4
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
erosion because prevention is always
more effective than having to trap al-
ready-eroded sediment particles in
runoff. Erosion and sediment controls
should be installed during initial site
preparation.
The most basic method of control is
physical screening of areas to remain
undisturbed. Properly chosen, installed,
and maintained sediment control mea-
sures can provide a significant degree of
filtration for sediment-bearing runoff
(Figure 9.2).
Where undisturbed areas lie downslope
of implementation activities, one
method of controlling sediment is the
use of a silt fence, which is normally
made of filter fabric. Silt fences can pro-
vide a significant degree of filtration for
sediment-bearing runoff, but only if
correctly chosen, installed, and main-
tained. Design guidelines for silt fences
include the following:
Drainage area of 1 acre or less.
Maximum contributing slope gradi-
ent of 2 horizontal to 1 vertical.
Maximum upslope distance of 100 ft.
Maximum flow velocity of 1 ft./sec.
Installation is even more critical than
material type; most fabric fences fail be-
cause either runoff carves a channel be-
neath them or sediment accumulates
against them, causing them to collapse.
To help prevent failure, the lower edge
of the fabric should be placed in a 4-
to 12-inch-deep trench, which is then
backfilled with native soil or gravel, and
wire fencing should be used to support
the fabric.
Figure 9.3 presents example silt fence
installation guidelines. Properly in-
stalled silt fences commonly fail due to
lack of maintenance. One rainfall event
can deposit enough sediment that fail-
ure will occur during the next rainfall
Figure 9.2: Silt fence at a construction site.
Properly chosen and installed silt fences can
provide a significant degree of off-site sedi-
ment control.
event if the sediment against the fence
is not removed.
Straw bales are also common sediment
control measures. Bales should be
placed in trenches about 4 inches deep,
staked into the ground, and placed with
their ends (not just corners) abutting
each other. Figure 9.4 presents example
straw bale installation guidelines. The
limitations on siting are the same as for
silt fences, but straw bales are typically
less durable and might need to be re-
placed.
Where the scope of a project is so small
that no official erosion control plans
have been prepared, control measures
should be appropriate to the site, in-
stalled promptly, and maintained ap-
propriately.
Proper restoration implementation re-
quires managers to prepare for "unex-
pected" failure of erosion control
measures. By the time moderate to
heavy rains can be expected, the follow-
Erosion and
sediment con-
trols should be
installed dur-
ing initial site
preparation.
Restoration Implementation
9-5
-------
Joints in filter fabric shall be spliced
at posts. Use staples, wire rings, or
equivalent to attach fabric to posts.
2"x2" 14 ga. wire
mesh or equivalent, if
standard strength
fabric used
filter fabric
Post spacing may be increased
to 8' if wire backing is used.
Minimum
4"x 4" trench.
Backfill trench with
native soil or 3/4"-1/5
washed gravel.
2"x 4" wood posts, steel
fence posts, rebar, or equivalent
Note: Filter fabric fences shall be installed along contour whenever possible.
Figure 9.3: Silt fence installation guidelines.
Erosion control measures must be installed
properly.
Source: King County, Washington.
Figure 9.4: Straw
bale installation
guidelines. Straw
bales are common
sediment control
measures.
Source: King County,
Washington.
o
baled hay
or straw
1
Notes:
Embed bales 4" to 6".
Drive stakes min. 12"
into ground surface.
centerline of
swale or ditch
I
B
2-2"x 2"x 3" pegs
each bale
overlap
edges
ing preparations should have been
made:
Additional erosion control materials
should be stockpiled on site, includ-
ing straw bales, filter fabric and wire
backing, posts, sand and burlap bags,
and channel lining materials (rock,
geotextile fabric or grids, jute netting,
coconut fabric material, etc.).
Inspection of the construction site
should occur during or immediately
after a rain storm or other significant
runoff event to determine the effec-
tiveness of sediment control mea-
sures.
A telephone number for the site
superintendent or project manager
should be made available to neigh-
boring residents if they witness any
problems on or coming from the
site. Residents should be educated on
what to watch for, such as sediment-
laden runoff or failed structures.
Water Quality
Although sediment is the major source
of water quality impairment on con-
struction sites, it is not the only source.
Motorized vehicles and equipment or
improperly stored containers can leak
9-6
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
petroleum products. Vehicles should be
steam-cleaned off site on a regular basis
and checked for antifreeze leaks and re-
paired. (Wildlife can be attracted to the
sweet taste of most antifreeze and poi-
soned.) Various other chemicals such as
fertilizers and pesticides can be washed
off by rain. Most of these problems can
be minimized or avoided entirely by
thoughtful siting storage areas for
chemicals and equipment and staging
areas. Gradients should not favor rapid
overland flow from these areas into ad-
jacent streams and wetlands. Distances
should be as great as possible and the
intervening vegetation as dense as site
traffic will allow.
Occasionally, implementation activities
will require the entry or crossing of
heavy equipment into the stream chan-
nel (Figure 9.5). Construction site
planning and layout should always seek
to avoid these intrusions. When these
intrusions are absolutely necessary, they
should be infrequent. Gravelly
streambeds are best able to receive traf-
fic; finer substrates should be reinforced
with a geoweb network backfilled with
gravel. In addition, any equipment used
in these activities should be thoroughly
steam-cleaned prior to stream entry.
Application of fertilizers and pesticides
can also be a source of pollution into
water bodies, and their use may be
closely regulated in restoration settings.
Where their use is permitted, the site
manager should closely monitor the
quantity applied, the local wind condi-
tions, and the likelihood of rainfall.
Potential water quality impacts are a
function of the characteristics of the se-
lected pesticide, its form, mode of appli-
cation, and soil conditions. Pesticides
and fertilizers must be stored in a
locked and protected storage unit that
provides adequate protection from leaks
and spills. Pesticides must be prepared
or mixed far from streams and, where
Figure 9.5: Heavy equipment. Avoid heavy
equipment in stream channels unless absolutely
necessary.
possible, off site. All containers should
be rinsed and disposed of properly.
Air Quality
Air quality in the vicinity of a restora-
tion site can be affected by vehicle
emissions and dust. Rarely, however,
will either be a major concern during
implementation activities. Vehicle emis-
sions are regulated at the source (the
vehicle), and dust is usually associated
primarily with haul roads or major
earthmoving during dry periods. The
need for dust control should be evalu-
ated during initial restoration imple-
mentation and road planning (if not
previously determined during the plan-
ning phase of the restoration initiative).
Site conditions, duration of construc-
tion activities, prevailing winds, and
proximity to neighbors should be con-
sidered when making decisions on dust
control. Temporary road surfaces or pe-
riodic water spraying of the road surface
are both effective in controlling dust.
Covered loads and speed limits on all
temporary roads will also reduce the
Restoration Implementation
9-7
-------
potential for construction-related dust
and debris leaving the site (Hunt
1993). Where appropriate, use of vol-
unteer labor in lieu of diesel-powered
equipment will help to protect air qual-
ity in and surrounding the site. Due to
safety concerns, it is recommended that
volunteers not be used on a site where
heavy equipment will also be used.
Cultural Resources
Since stream corridors have been a
powerful magnet for human settlement
throughout history, it is not uncommon
for historic and prehistoric resources to
be buried by sediment or obscured by
vegetation along stream corridors. It is
quite possible to discover cultural re-
sources during restoration implementa-
tion (particularly during restoration
that requires earth-disturbing activities).
(See Figure 9.6.)
Prior to implementation, any potential
cultural resources should be identified
in compliance with section 106 of the
National Historic Preservation Act. An
archaeological record search should be
Figure 9.6: Archaeological site. Cultural
resources, such as those at this site in South
Dakota, are commonly found near streams.
conducted during the planning process
in accordance with the State Historic
Preservation Officer (SHPO). If a site is
uncovered unexpectedly, all activity that
might adversely affect the historic prop-
erty must cease, and the responsible
agency official must notify the U.S. De-
partment of the Interior (USDI) Na-
tional Park Service and the SHPO.
Upon notification, the SHPO deter-
mines whether the activity will cause an
irreparable loss or degradation of signif-
icant data. This might require on-site
consultation with a 48-hour response
time for determining significance and
appropriate mitigation actions so as not
to delay implementation activities inor-
dinately.
If the property is determined not to be
significant or the action will not be ad-
verse, implementation activities may
continue after documenting consulta-
tion findings. If the resource is signifi-
cant and the on-site activity is
determined to be an adverse action that
cannot be avoided, implementation ac-
tivities are delayed until appropriate ac-
tions can be taken (i.e., detailed survey,
recovery, protection, or preservation of
the cultural resources). Under the His-
torical and Archaeological Data Preser-
vation Act of 1974, USDI may assume
liability for delays in implementation.
Noise
Noise from restoration sites is regulated
at the state or local level. Although cri-
teria can vary widely, most establish
reasonable and fairly consistent stan-
dards.
The U.S. Housing and Urban Develop-
ment (HUD) agency has set a maxi-
mum acceptable construction noise
emission of 65 A-weighted decibels
(dBA) at the property line. Numerous
studies conducted since the late 1960s
suggest that community complaints rise
dramatically above 55 dBA (Thumann
9-8
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
and Miller 1986). Meeting the HUD
standard (65 dBA) requires that typical
construction equipment be over 300
feet away from the listener; avoiding the
chance of any significant complaints re-
quires about 500 feet of separation or
more. The project manager should con-
tact surrounding neighbors prior to
restoration implementation. Public
awareness of and appreciation for the
project goals help improve tolerance for
off-site noise impacts. (Impacts from
noise on equipment operators is usu-
ally not significant since most construc-
tion equipment meets the noise
standards imposed by the U.S. General
Services Administration of 75 dBA at 50
feet.)
High noise levels might be a concern to
wildlife as well, particularly during the
breeding season. Any sensitive species
that inhabit the project vicinity should
be identified and appropriate actions
taken to reduce noise levels that could
adversely affect these species.
Solid Waste Disposal
Debris is an inevitable by-product of
implementation activities. The manage-
ment of debris is a matter of job site
safety, function, and aesthetics. From
the first day, the locations of equipment
storage, vehicle unloading, stockpiled
materials, and waste should be identi-
fied. At the end of each workday, all
scattered construction debris, plant ma-
terials, soil, and tools should be gath-
ered up and brought to their respective
holding areas. The site should be left as
neat and well organized as possible at
the end of each day. Even during the
workday, sites in close proximity to
business or residential districts should
be kept as well organized and "sightly"
as possible to avoid complaints and de-
lays initiated by unhappy neighbors.
The importance of these measures to
the safety and efficiency of the restora-
tion effort as a whole is sometimes evi-
dent only to the project manager.
Under such conditions, achieving ade-
quate job site cleanliness is almost im-
possible because the manager alone
does not have time to tidy up trash and
debris. Meetings with work crews to
emphasize this element of the work
should occur early in the construction
process and be repeated as often as re-
quired. People working on site, whether
contractors, volunteers, or government
personnel, need to be reminded of
these needs as an unavoidable part of
doing their jobs.
Worksite Sanitation
Sanitation facilities for work crews
should be identified before construc-
tion begins. Particularly in remote
areas, the temptation to allow ad hoc
arrangements will be high. In urban
areas, the existing facilities of a neigh-
boring business might be offered. In
most settings, however, one or more
portable toilets should be provided and
might be required by local building or
grading permits. Although normally
self-contained, any facilities should be
located to minimize the risk of contam-
ination of surface water bodies by leak-
age or overflow.
Obtaining Appropriate
Equipment
Standard earthmoving and planting
equipment is appropriate for most
restoration work. Small channels or
wetland pool areas can be excavated
with backhoes or track-mounted exca-
vators or trackhoes. Trackhoes are mo-
bile over rough or steep terrain (Figure
9.7). They have adequate reach and
power to work at a distance from the
stream channel; with an opposing
"thumb" on the bucket, they can ma-
neuver individual rocks and logs with
remarkable precision. Logs can also be
Restoration Implementation
9-9
-------
Figure 9.7: Backhoe
in operation at a
restoration site.
Backhoes are
mobile in rough
terrain and can
move rocks and
logs with remark-
able precision.
Source: M. Landin.
placed by a helicopter's cable. Although
the hourly rate is about that of the daily
cost of ground-based equipment, the
ability to reach a stream channel with-
out use of an access road is sometimes
indispensable.
Where access is good but the riparian
corridor is intact, instream modifica-
tions can be made with a telescoping
crane. This equipment comes in a vari-
ety of sizes. A fairly large, fully mobile
unit can extend across a riparian zone
100 feet wide to deliver construction
materials to a waiting crew without dis-
turbing the intervening ground or vege-
tation. Where operational constraints
permit their use, bulldozers and scrap-
ers can be very useful, particularly for
earthmoving activities that are ab-
solutely necessary to get the job done.
In addition, loaders are excellent tools
for transporting rocks, transplanting
large plants, and digging and placing
sod.
For planting, standard farm equipment,
such as tractors with mounted disks or
harrows, are generally suitable unless
the ground is extremely wet and soft.
Under these circumstances, light-track-
ing equipment with low-pressure tires
or rubber tracks might work. Seeds
planted on restoration sites are com-
monly broadcast by hydroseeding, re-
quiring a special tank truck with a
pump and nozzle for spraying the mix-
ture of seeds, fertilizer, binder, and
water (Figure 9.8). A wider range of
seed species can be planted more effec-
tively with a seed drill towed behind a
tractor (e.g., Haferkamp et al. 1985).
Where access is limited, hand planting
or aerial spreading of seeds might be
feasible.
Site Clearing
Once the appropriate construction
equipment has been acquired and site
preparation has been completed, any
necessary site clearing can begin. Site
clearing involves setting the geographic
limits, removing undesirable plant
species, addressing site drainage issues,
and protecting and managing desirable
existing vegetation.
Geographic Limits
Site clearing should not proceed unless
the limits of activity have been clearly
marked in the field. Where large trees
are present, each should be marked
with colored and labeled flagging to en-
sure that the field crew understands
what is to be cut and what is to remain
and be protected from damage.
Removal of Undesirable Plant
Species
Undesirable plant species include non-
native and invasive species that might
threaten the survival of native species.
Undesirable plants are normally re-
moved by mechanical means, but the
specific method should be tailored to
the species of concern if possible. For
example, simply cutting the top growth
9-10
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
Figure 9.8: Hydroseeding of a streambank.
Special tank trucks carrying seed, water, and
fertilizer can be used in revegetation efforts.
might be adequate management for
some plants, but others might resprout
rapidly. Where herbicides are selected
(and permitted), their use might need
to precede clearing of the top growth
by up to 2 weeks to allow full absorp-
tion of certain chemicals used for this
purpose.
For initial brush removal, a variety of
track-mounted and towed equipment
is available. Bulldozers are most com-
monly used because of their ready
availability, but other equipment can
often work more rapidly or more
effectively with minimal site distur-
bance.
Hand clearing with portable tools
might be the only appropriate method
in some sensitive or difficult areas.
Drainage
Sites that are very wet and poorly
drained might require extra prepara-
tion. However, many of the traditional
efforts to improve drainage are in par-
tial or direct conflict with wetland-pro-
tection regulations and might conflict
with the restoration goals of the project
as a whole. Standard engineering ap-
proaches should be reviewed for appro-
priateness, as well as the timing and
schedule of the restoration activities.
Specific techniques for improving the
workability of a wet construction site de-
pend on the particular access, storage
needs, and site characteristics. Load-bear-
ing mats can provide stable areas for
equipment and the unloading of plant
materials. Surface water may be inter-
cepted above the working area by a shal-
low ditch and temporarily routed
around the construction area. Subsurface
water can sometimes be intercepted by a
perforated pipe set in a shallow trench,
such as a French drain, but the topogra-
phy must be favorable to allow positive
drainage of the pipe to a surface outlet.
Restoration Implementation
9-11
-------
Protection and Management of
Existing Vegetation
Protecting existing vegetation on a
restoration site requires a certain degree
of attention and advanced planning. An
area on a site plan that is far from all
earthmoving activity might appear to
the site foreman as the ideal location
for parking idle equipment or stockpil-
ing excess soil. Only a careless minute
with heavy equipment, however, can re-
duce a vegetated area to churned earth
(Figure 9.9). Vegetation designed for a
protection zone should be clearly
marked in the field.
Existing vegetation might also require
temporary protection if it occupies a
part of the site that will be worked, but
only late in the implementation se-
quence. Before that time, it is best left
undisturbed to improve the level of
overall erosion control. To save mobi-
lization costs, most earthmoving con-
tractors normally begin construction by
clearing every part of the site that will
eventually require it. If clearing is to be
phased instead, this requirement must
Figure 9.9: Lessons to be learned. Heavy equip-
ment can quickly reduce a vegetated area to
churned earth.
be specified in the contract documents
and discussed at a preimplementation
meeting.
When identifying and marking vegeta-
tion protection zones, the rooting ex-
tent of the vegetation should be
respected. Fencing and flagging of pro-
tected vegetation should be sturdy and
maintained. Despite the cool shade and
fencing, vegetation protection zones are
neither a picnic area nor a storage/stag-
ing area. They are zones of no distur-
bance.
When working in riparian corridors
with mature conifers, it is especially im-
portant to protect them from mechani-
cal operations which can cause severe
damage.
Installation and Construction
Following site preparation and clearing,
restoration installation activities such as
earthmoving, diversion of flow, and the
installation of plant materials can pro-
ceed.
Earthmoving
Fill Placement and Disposal
How and where fill is placed on a site
should be determined by the final
placement of restoration measures. Fills
adjacent to retaining walls or similar
structures need to meet the criteria for
structural fill.
Where plants will be the final treatment
of a fill slope, the requirements for soil
materials and compaction are not as se-
vere. Loose soil on a steep slope is still
prone to erosion or landsliding, how-
ever. Where fill is to be placed on
slopes steeper than about 2:1, a soils
engineer should determine whether any
special measures are appropriate (Fig-
ure 9.10). Even on gentler slopes, sur-
face runoff from above should not be
allowed to saturate the new material
9-12
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
typical face angle
for rockeries,
gabions, etc.
soil engineer review
or supervision
advisable
biotechnical: combination of
stabilization structures, soil
bioengineering, and geotechnical
methods often needed
failure likely
in unreinforced
cuts
roughen,
airstep, or
e slope for
failure likely
unreinforced
fills -""plantin
optimal range for
soil bioengineering
plantings/seedings
horizontal
Figure 9.10: Treatment of cuts and fills. Slope
gradient is an important factor in determining
appropriate restoration measures.
since the stability of noncompacted fills
is generally quite low.
To reduce grading expenses, the cut and
fill should be balanced so no material
needs to be transported to or from the
site. If the volume of material resulting
from cuts exceeds that from fills, some
of the soil must be disposed of off-site.
Disposal sites can be difficult to locate
and might require an additional grad-
ing permit from the local jurisdiction.
These possibilities should be planned
for far enough in advance to avoid
unanticipated delays during implemen-
tation.
As a general rule, topsoil removed from
the site should be properly stockpiled
for reuse during the final stages of im-
plementation. Even if undesirable
species are present, the topsoil will pro-
vide a growth medium suitable for the
plant community appropriate to the
site. It will also be a source of native
species that can reestablish the desired
diversity most rapidly (Liebrand and
Sykora 1992). Stockpiled soil also can
be vegetated with species that will be
used at the restoration site to protect
the soil from erosion and noxious
weeds.
Contouring
The erosive power of water flowing
down a slope should be recognized
during earthmoving. The steepest direc-
tion down a hillside is also the direc-
tion of greatest erosion by overland or
channelized flow. The overall topogra-
phy of the graded surface should be de-
signed to minimize the uncontrolled
flow of runoff in this direction. Chan-
nelized flow should be diverted to
ditches cut into the soil that more
closely follow the level contours of the
land. Dispersed sheet flow should be
broken up by terraces or benches along
the slope that also follow topographic
contours. On a fine scale, the ground
surface can be roughened by the tracks
of a bulldozer driven up and down the
slope, or by a rake or harrow pulled
perpendicularly to the slope. In either
case, the result is a set of parallel ridges,
spaced only a few inches apart, that fol-
low the contours of the land surface
and greatly reduce on-site erosion.
Earthmoving
should result
in a slope that
is stable, mini-
mizes surface
erosion by
virtue of
length and
gradient, and
provides a fa-
vorable envi-
ronment for
plant growth.
Restoration Implementation
9-13
-------
Figure 9.11: Track-
roughened area.
Rough-textured
slopes provide a
much better environ-
ment for seedlings
than do smooth-
packed surfaces.
Final Grading
Earthmoving should result in a slope
that is stable, minimizes surface erosion
by virtue of length and gradient, and
provides a favorable environment for
plant growth. The first two criteria are
generally determined by plans and can
be modified only minimally by varia-
tions in grading techniques. Where
plans specify a final slope gradient
steeper than about 1:1, however, vegeta-
tion reestablishment will be very diffi-
cult, and a combination of stabilization
structures, soil bioengineering, and ge-
otechnical methods will probably be
necessary. The shape at the top of the
slope is also important: if it forms a
straight abrupt edge, plant regrowth will
be nearly impossible. A rounded edge
that forms a gradual transition between
upland and slope will be much more
suitable for growth (Animoto 1978).
Providing a favorable environment for
plant growth requires attention to the
small-scale features of the slope. Rough-
textured slopes, resulting from vehicle
tracks or serrated blades, provide a
much better environment for seedlings
than do smooth-packed surfaces (Fig-
ure 9.11). Small terraces should be cut
into slopes steeper than about 3:1 to
create sites of moisture accumulation
and enhanced plant growth. Com-
paction by excessive reworking from
earthmoving equipment can result in a
lower rate of rainfall infiltrating the soil
and, consequently, a higher rate of ero-
sive surface runoff. The result is a loss
of the topsoil needed to support plant
growth and less moisture available for
the plants that remain.
Diversion of Flow
Channelized flow (from stream chan-
nels, ditches, ravines, or swales) might
need to be diverted, impounded, or
otherwise controlled during implemen-
tation of restoration measures. In some
cases, this need might be temporary,
until final grading is complete or plant-
ings have become established. In other
cases, the diversion is a permanent part
of the restoration. Permanent facilities
frequently replace temporary measures
at the same location but are often con-
structed of different materials.
Temporary dikes, lined or grassed water-
ways, or pipes can be used to divert
channelized flow. Runoff can also be
impounded in ponds or sediment
basins to allow sediment to settle out.
Most temporary measures are not engi-
neered and are constructed from mate-
rials at hand. Dikes (ridges of soil up to
a few feet high) are compacted to
achieve some stability and are some-
times armored to resist erosion. They
are used to keep water from washing
over a newly graded or planted slope
where erosion is otherwise likely, and
to divert runoff into a natural or artifi-
cial channel. The loosened soil from
swales can be readily compacted into
an adjacent dike, improving the
efficiency and capacity of the runoff di-
version. Pipes or rock-lined ditches can
carry channelized water down a slope
that is steep enough to otherwise suffer
erosion; they can also be used to halt
erosion that has already occurred from
9-14
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
uncontrolled discharges. Flexible plastic
pipe is most commonly used in these
situations, although the outlet must be
carefully located or well armored with
rocks or sandbags to avoid merely shift-
ing the point of erosion farther down-
slope.
Sediment ponds and traps are basins ei-
ther dug into the soil with a rock-ar-
mored overflow or impounded by an
embankment with an outlet. A fraction
of the sediment carried by the site
runoff will settle out in the trap, de-
pending on the ratio of surface area or
storage volume to inflow rate. The util-
ity of sediment ponds may be limited
depending on the sediment-trapping ef-
ficiency. A sediment pond can also re-
lease nearly as much sediment as is
ultimately trapped if the pond is not
built to handle maximum surface water
flows or is not maintained properly.
Several techniques are available where
the active streamflow must be tem-
porarily isolated from installation activ-
ities. Most common are temporary
dams, constructed of sandbags, geotex-
tile fences, water control structures, or
sheet piles. All may be suitable in cer-
tain situations, but have drawbacks.
Sandbags are inexpensive, but sub-
merged burlap sacks rot quickly and the
sand used to fill them might not be ap-
propriate for the stream. Fabric fences
can be used in conjunction with sand-
bags, but they will not withstand high
flows. Water control structures, such as
long water-filled tubes available com-
mercially, can be very effective, but need
ample lateral space and carry a high ini-
tial cost. They also can be swept away
by high flows. Sheet piles are effective if
heavy equipment is already on site, but
their installation and removal can mo-
bilize much fine sediment.
Alternatively, water can be diverted into
a bypass pipe, normally made of large
flexible plastic (unless anticipated dis-
charges are very great), and the con-
struction area can be kept totally and
reliably dry. A dam must be constructed
at the pipe inlet to shunt the water, and
an adequate apron of nonerosive mater-
ial must be provided at the discharge.
Both of these structures can themselves
lead to instream damage, but with care
the problems are only temporary. Since
fish passage and migration are generally
precluded with such a diversion, its ap-
plicability is limited.
In some situations unexpectedly erosive
conditions will demand better outlet or
channel protection than that originally
specified in the plans. Erosion control
in these settings might require a thick
blanket of angular rocks and geotextiles
(cloth, plastic grids, or netting) used
with plantings. New types of geotextiles
are becoming widely available and can
serve a wide range of flow conditions.
Where possible, channels and spillways
should be stabilized using soil bioengi-
neering or other appropriate techniques.
Installation of Plant Materials
Plant establishment is an important
part of most restoration initiatives that
require active restoration. Detailed local
standards and specifications that de-
scribe planting techniques and estab-
lishment procedures should be
developed. Native species should be
used where possible to achieve the
restoration goals. Vegetation can be in-
stalled by seeding; planting vegetative
cuttings; or using nursery-grown bare-
rooted, potted, and burlap-wrapped
specimens. If natural colonization and
succession is appropriate, techniques
may include controlling exotic species
and establishing an initial plant com-
munity to hasten succession.
Plant establish-
ment is an
important
part of most
restoration
initiatives that
require active
restoration.
Restoration Implementation
9-15
-------
Timing
The optimum conditions for successful
plant installations are broad and vary
from region to region. As a general rule,
temperature, moisture, and sunlight
must be adequate for germination and
establishment. In the eastern and mid-
western United States, these conditions
are met beginning in late winter or
early spring, after ground thawing, and
continuing through mid-autumn. In the
West, the typical summertime dryness
normally limits successful seedings to
late summer or early autumn. Where
arid conditions persist through most of
the year, plants and seedings must take
advantage of whatever rainfall occurs,
typically in late autumn or winter, or
supplemental irrigation must be pro-
vided. Because the requirements can
vary so much for different species, the
local supplier or a comprehensive refer-
ence text (e.g., Schopmeyer 1974, Ford-
ham and Spraker 1977, Hartmann and
Kester 1983, Dirr and Heuser 1987)
should be consulted early in the
restoration design phase. If rooted stock
is to be propagated from seed before it
is planted at the restoration site, 1 to 2
years (including seed-collection time)
should be allowed.
Plants should be installed when dor-
mant for the highest rate of survival.
Survival is further influenced by species
used and how well they are matched to
site conditions, available moisture, and
time of installation. In mild climates,
the growth of roots occurs throughout
the winter, improving survival of fall
plantings. Where high wintertime flows
are anticipated, however, first-season
cuttings might not survive unless given
some physical protection from scour.
Alternatively, planting can occur in the
spring before dormancy ends, but sup-
plemental irrigation might be needed
even in areas of abundant summertime
rainfall. Irrigation might be necessary in
some regions of the country to ensure
successful establishment of vegetation.
Acquisition
Native plant species are preferred over
exotic ones, which might result in un-
foreseen problems. Some plant materi-
als can be obtained from commercial
sources, but many will need to be col-
lected. When attempting to restore na-
tive plant communities, it is desirable
to use appropriate genotypes. This re-
quires the collection of seeds and plants
from local sources. Early contact with
selected sources of rooted stock and
seed can ensure that appropriate species
in adequate quantities will be available
when needed.
The site itself might also be a good
source of salvageable plants. Live cut-
tings can be collected from healthy na-
tive vegetation at the donor site. Sharp,
clean equipment must be used to har-
vest the plant material. Vegetation is
normally cut at a 40 to 50 degree angle
using loppers, pruners, or saws. If the
whole plant is being used, the cut is
made about 10 inches above the
ground, which encourages rapid regen-
eration in most species. Cuttings typi-
cally range from 0.4 to 2 inches in
diameter and 2 to 7 feet long.
After harvesting, the donor site should
be left in a clean condition. This will
avoid the potential for landowner com-
plaints and facilitate potential reuse of
the site at some time in the future.
Large unused material can be cut for
firewood, piled for wildlife cover, or
scattered to hasten decomposition. Any
diseased material should be burned, per
local ordinances.
Transportation and Storage
The requirements for the transport and
storage of plant materials vary, depend-
ing on the type of material being used.
Depending on species, seeds may require
a minimum period of dormancy of sev-
9-16
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
eral weeks or months, with specific tem-
perature requirements during that time.
Some seeds may also require scarifying
or other special treatment. Nurseries that
specialize in native plants are recom-
mended because they should be cog-
nizant of any special requirements.
Although the necessary information for
any chosen species should be readily
available from local seed sources or agri-
cultural extension offices, this interval
must be recognized and accounted for in
the overall implementation schedule.
Live cuttings present rather severe limi-
tations on holding time. In most cases,
they should be installed on the day they
are harvested, unless refrigerated storage
areas are secured. Thus, donor sites must
be close to the restoration site, and ac-
cess and transportation must be orches-
trated to coincide with the correct stage
of construction. Live cuttings should be
tied in manageable bundles, with the
cut ends all lying in the same direction.
Since drying is the major threat to sur-
vival at this stage, cuttings should be
covered with damp burlap during trans-
port and storage (Figure 9.12). They
Figure 9.12: Live cuttings covered with damp
burlap to prevent drying during transport.
Drying is a major threat to survival of live
cuttings during transport and storage.
should always be shaded from direct
sun. On days with low humidity and
temperatures above 60 degrees Fahren-
heit, the need for care and speed is par-
ticularly great. Where temperatures are
below this level, "day-after" installation
is acceptable, although not optimal. Any
greater delay in installation will require
refrigeration, reliably cold weather on
site, or storage in water.
Rooted stock is also prone to drying,
particularly if pots or burlap-wrapped
roots are exposed to direct sun. Sub-
mergence of the roots in water is not
recommended for long periods, but 1
to 2 hours of immersion immediately
prior to planting is a common practice
to ensure the plant begins its in-place
growth without a moisture deficit. On-
site storage areas should be chosen with
ample shade for pots. Bare-rooted or
burlap-wrapped stock should be heeled
into damp ground or mulch while
awaiting final installation.
Planting Principles
The specific types of plants and plant
installations are generally specified in
the construction plans and therefore
will have been determined long before
implementation. A project manager or
site foreman should also know the
basic installation principles and tech-
niques for the area.
The type of soil used should be deter-
mined by the types of plants to be sup-
ported. Ideally, the plants have been
chosen to match existing site condi-
tions, so stockpiled topsoil can be used
to cover the plant material following
layout. However, part of the rehabilita-
tion of a severely disturbed site might
require the removal of unsuitable top-
soil or the import of new topsoil. In
these situations, the requirements of the
chosen plant species should be deter-
mined carefully and the soil procured
from suitable commercial or field sites
Restoration Implementation
9-17
-------
that have no residual chemicals and un-
desirable plant species.
When using seeds, planting should be
preceded by elimination of competing
plants and by preparation of the
seedbed (McGinnies 1984). The most
common methods of seeding in a
restoration setting are hand broadcast-
ing and hydroseeding. Hydroseeding
and other methods of mechanical seed-
ing might be limited by vehicular access
to the restoration site.
When using either cuttings or rooted
stock, the soil and the roots must make
good contact. This requires compaction
of the soil, either by foot or by equip-
ment, to avoid air pockets. It also re-
quires that the soil be at the right
moisture content. If it is too dry (a rare
condition), the soil particles cannot
"slip" past each other to fill in voids. If
it is too wet (far more common, espe-
cially in wetland or riparian environ-
ments), the water cannot squeeze out of
the soil rapidly enough to allow com-
paction to occur.
Another aspect to consider is that quite
frequently after planting, the resulting
soil is too rough and loose to support
vigorous seed growth. The roughness
promotes rapid drying, and the loose-
ness yields poor seed-to-soil contact
and also erratic planting depths where
mechanical seed drills are used. As a re-
sult, some means of compaction should
be employed to return the soil to an ac-
ceptable state for planting.
Special problems may be encountered
in arid or semiarid areas (Anderson et
al. 1984). The salt content of the soil in
these settings is critical and should be
tested before planting. Deep tillage is
advisable, with holes augured for
saplings extended to the water table if
at all possible. First-year irrigation is
mandatory; ongoing fertilization and
weeding will also improve survival.
Competing Plants
Although a well-chosen and established
plant community should require no
human assistance to maintain vigor and
function, competition from other plants
during establishment might be a prob-
lem. Competing plants commonly do
not provide the same long-term benefits
for stability, erosion control, wildlife
habitat, or food supply. The restoration
plan therefore must include some
means to suppress or eliminate them
during the first year or two after con-
struction.
Competing plants may be controlled
adequately by mechanical means. Cut-
ting the top growth of competing plants
can slow their development long
enough for the desired plants to be-
come established. Hand weeding is also
very effective, although it is usually fea-
sible only for small sites or those with
an ongoing source of volunteer labor.
Unfortunately, some species can survive
even the most extreme mechanical
treatment. They will continue to
reemerge until heavily shaded or
crowded out by dense competing
stands. In such cases the alternatives are
limited. The soil containing the roots of
the undesired vegetation can be exca-
vated and screened or removed from
the site, relatively mature trees can be
planted to achieve near-instantaneous
shading, or chemical fertilizers or herbi-
cides can be applied.
Use of Chemicals
In situations where mechanical controls
are not enough, the application of fer-
tilizers and the use of herbicides to sup-
press undesirable competing species
may be necessary.
Herbicides can eliminate undesirable
species more reliably, but they may
eliminate desirable species. Their use
near watercourses may also be severely
9-18
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
curtailed by local, state, and federal per-
mit requirements. Several herbicides are
approved for near-stream use and de-
grade quickly, but their use should be
considered a last resort and the effects
of excessive spray or overspray carefully
controlled.
If herbicide use is both advisable and
permitted, the specific choice is based
first on whether the herbicide is ab-
sorbed by the leaves or by the roots
(e.g., Jacoby 1987). The most common
foliar-absorbed herbicide is 2,4-D, man-
ufactured by numerous companies and
particularly effective on broadleaf weeds
and some shrubs. Other foliar herbi-
cides have become available more re-
cently and are commonly mixed with
2,4-D for broad-spectrum control. Root-
absorbed herbicides are either sprayed
(commonly mixed with dye to show
the area of application) or spread in
granular form. They persist longer than
most foliar herbicides, and some are
formulated to kill newly sprouted
weeds for some time after application.
Since herbicides and fertilizers may be
problematic near surface water, they
should be used only if other alterna-
tives are not available.
Mulches
Mulching limits surface erosion, sup-
presses weeds, retains soil moisture, and
can add some organic material to the
soil following decomposition. A variety
of mulches are available with different
benefits and limitations, as shown in
Table 9.1.
Organic mulches, particularly those
based on wood (chips or sawdust),
have a high nitrogen demand because
of the chemical reactions of decomposi-
tion. If nitrogen is not supplied by fer-
tilizers, it will be extracted from the
soil, which can have detrimental effects
on the vegetation that is mulched. Cer-
tain species of wood, such as redwood
and cedar, are toxic to certain species of
seedlings and should not be used for
mulch.
Straw is a common mulch applied on
construction and revegetation sites be-
cause it is inexpensive, available, and ef-
fective for erosion control. Appropriate
application rates range from about
3,000 to 8,000 Ib/acre. Straw can be
spread by hand or broadcast by
machine, although uniform application
is difficult in windy conditions. Straw
must be anchored for the same reason:
it is easily transported by wind. It can
be punched or crimped into the soil
mechanically, which is rapid and inex-
pensive, but requires high application
rates. It can be covered with jute or plas-
tic netting, or it can be covered with a
sprayed tackifier (usually asphalt emul-
sion at rates of about 400 gal/acre).
Straw or hay can also be a source of un-
Since herbi-
cides and
fertilizers may
be problematic
near surface-
water, they
should be used
only if other
alternatives are
not available.
Benefits
Limitations
Chipped wood Readily available; inexpensive;
judged attractive by most
Rock May be locally available and
inexpensive
Straw or hay Available and inexpensive; may
add undesirable seeds
Hydraulic Blankets soil rapidly and
mulches inexpensively
Fabric mats Relatively (organic) or very (inorganic)
durable; works on steep slopes
Commercial Excellent soil amendment at
compost moderate cost
High nitrogen demand; may inhibit seedlings;
may float offsite in surface runoff
Can inhibit plant growth; adds no nutrients;
suppresses diverse plant community; high cost
where locally unsuitable or unavailable
May need anchoring; may include undesirable
seeds
Provides only shallow-rooted grasses, but may
out compete woody vegetation
High costs; suppresses most plant growth;
inorganic materials harmful to wildlife
Limited erosion-control effectiveness; expensive
over large areas
Table 9.1: Types
of mulches.
Restoration Implementation
9-19
-------
The value of
an effective
mulch to the
final success
of an initiative
is generally
well in excess
of its cost,
even when
the most ex-
pensive treat-
ment is used.
desirable weed seed and should be in-
spected prior to application.
Wood fibers provide the primary me-
chanical protection in hydraulic
mulches (usually applied during hy-
droseeding). Rates of 1 to 1.5 tons/acre
are most effective. They can also be ap-
plied as the tackifier over straw at about
one-third the above rate. Hydraulic
mulches are adequate, but not as effec-
tive as straw, for controlling erosion in
most settings. However, they can be ap-
plied on slopes steeper than 2:1, at dis-
tances of 100 feet or more, and in the
wind. On typical earthmoving and con-
struction projects, they are favored be-
cause of the speed at which they can be
applied and the appearance of the re-
sulting slopetidy, smooth, and faintly
green. The potential drawbacksintro-
ducing fertilizers and foreign grasses
that are frequently mixed into hydraulic
mulchesshould be carefully evalu-
ated.
An appropriate mulch in many restora-
tion settings is a combination of straw
and organic netting, such as jute or
coconut fibers (Figure 9.13). It is the
most costly of the commonly used sys-
tems, but erosion control and moisture
retention are highly effective, and the
problems with undesirable seeds and
excess fertilizers are reduced. The value
of an effective mulch to the final suc-
cess of an initiative is generally well in
excess of its cost, even when the most
expensive treatment is used.
Irrigation
In any restoration that involves replant-
ing, the need for irrigation should be
carefully evaluated. Irrigation might not
be needed in wetland and near-stream
riparian sites or where rainfall is well
distributed throughout the year. Irriga-
tion may be essential to ensure success
on upland sites, in riparian zones where
seasonal construction periods limit in-
stallation to dry months, or where a
wet-weather planting may have to en-
dure a first-year drought. Initial costs
are lowest with a simple overhead
spraying system. Spray systems, how-
ever, have inefficient water delivery and
have heightened potential for vandal-
ism. Drip-irrigation systems are there-
fore more suitable at many sites
(Goldner 1984). There is also a greater
potential for undesirable species with
spray irrigation since the area between
individual plants receives moisture.
Fencing
If the plant species chosen for the site
are suitable, little or no special effort
will be necessary for survival and estab-
lishment. During the initial construc-
tion and postconstruction phases,
however, plants will commonly need
some measure of physical protection.
Construction equipment, work crews,
onlookers, grazing horses and cattle,
and browsing deer and other herbivores
can reduce a new plant installation to
barren or crushed twigs in very short
order. Vandalism is also a potential
problem in populated areas. Fencing is
an effective, low-cost method to provide
Figure 9.13: A well-mulched site. Mulching is
an effective method for improving the final
outcome of stream corridor restoration.
9-20
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
physical protection from these types of
hazards and should be included in vir-
tually any restoration.
The type of fencing should be chosen
for the type of hazard anticipated. Inex-
pensive, fluorescent orange plastic fenc-
ing is very effective for controlling
people and equipment during construc-
tion, but it rarely makes a suitable long-
term barrier. Domestic cattle can be
controlled by a variety of wood and
wire fences (Figure 9.14). Depending
on the density of grazing animals, these
fences are best assumed to be perma-
nent installations and their design cho-
sen accordingly. Electric fences can also
be effective, and the higher cost of the
electrification equipment can be offset
by lower costs for materials and instal-
lation. Where deer are a known prob-
lem, fencing must be robust, but it
probably will not need to remain in
place permanently after well-chosen
plants have matured. Damage from
small mammals may be halted with
chicken wire alone, surrounding indi-
vidual saplings, or below-ground col-
lars. Individual wire cages or other
control devices might be necessary to
protect trees.
Inspection
Frequent, periodic inspection of work,
whether done by a landowner, contrac-
tor, volunteer group, or government
personnel, is mandatory. Defects such
as poor planting methods, stressed
plant materials, inadequate soil com-
paction, or sloppy erosion control, may
become evident only weeks or months
after completion of work unless the ac-
tivities on the site are regularly re-
viewed. Some of those activities may
require specialized testing, such as the
degree of compaction of a fill slope.
Most require little more than observa-
tions by an inspector familiar with all
elements of the design.
In the case of contracted work, it is the
responsibility of the construction in-
spector to monitor installation activities
to ensure that the contractor completes
work according to the contract plans
and specifications. At key points during
construction, the inspector should con-
sult with clients and design team(s) for
assistance. The inspector should create
comprehensive documentation of the
construction history in anticipation of
any future audit or quantity dispute. All
inspections should result in a written
record that includes at least the infor-
mation shown in Figure 9.15.
Daily and weekly reports are invaluable
to maintain clear communication about
billable days, progress, and anticipated
problems. These written reports estab-
lish the authority to release payment to
the contractor and provide the main
documentation in case of a dispute be-
tween the client and contractor. Com-
pleteness, timeliness, and clarity of
documentation are critical.
Inspection of restoration elements that
involve management actions (i.e., land-
use controls, grazing restrictions, etc.)
require follow-up communication with
the resource manager or landowner. A
Figure 9.14: A perma-
nent livestock fence.
Fencing is an effec-
tive, low-cost method
of providing physical
protection to restora-
tion sites.
Restoration Implementation
9-21
-------
Inspector's Daily Report
Date:
Project:
Contractor:
Inspector:
Temperature: H_
Work Done .
L Precip: Hours: Workable
Nonworkable
Contractor Equipment On-Site
Personnel On-Site
Materials Used and Location
Remarks
Inspection Time
Inspector's Signature.
Figure 9.15:
Sample of an
inspector's daily
report. Frequent,
periodic inspection
is a mandatory
part of restoration
implementation.
review of the action against the plan
and applicable standards should be
conducted. For example, rotational
grazing may be a critical plan element
to achieve restoration of the stream cor-
ridor. Inspection of this plan element
would involve a review of the rotation
scheme, condition of individual pas-
tures or ranges, and condition of fenc-
ing and related watering devices.
Keep in mind that although plans and
specifications should be specific to the
conditions of the site, they might have
been developed from generic sets or
from those implemented elsewhere.
On-Site Inspection Following
Installation
The final inspection after installation
determines the conditions under which
the contractor(s) can be paid and the
contract finalized. It must occur
promptly and should determine
whether all elements of the contract
have been fulfilled satisfactorily. Before
scheduling this final inspection, the
project manager and inspector, together
with any other necessary members of
the restoration team, inspect the work
and prepare a list of all items requiring
completion by the contractor. This "pre-
final" inspection is in fact the most
comprehensive review of the work that
will occur, so it must be conducted with
care and after nearly all of the work has
been completed. The final inspection
should occur with representatives of
both the client and the contractor pre-
sent after completion of all required
work and after site cleanup, but before
equipment is removed from the site to
facilitate additional work if necessary. It
must address removal of protection
measures no longer needed, such as silt
fences. These are an eyesore and might
inhibit restoration. A written report
should state the complete or provi-
sional acceptance of the work, the basis
on which that judgment has been
made, and any additional work that is
needed prior to final acceptance and
payment.
Follow-up Inspections
Planning for successful implementation
should always look beyond the period
of installation to the much longer inter-
val of plant establishment. Twelve or
more additional site visits are advisable
over a period of many months or years.
Such inspections will generally require
a separate budget item that must be an-
ticipated during restoration planning. If
they are included in the specifications,
they may be the responsibility of the
contractor. A sample inspection sched-
ule is shown in Table 9.2. Although this
level of activity after installation might
seem beyond the scope of a project, any
restoration work that depends on the
9-22
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
growth of vegetation will benefit greatly
from periodic review, particularly dur-
ing the first two years.
Documentation of follow-up inspec-
tions is important, both to justify rec-
ommendations and to provide a record
from which chronic problems can be
identified. Documentation can include
standard checklists, survey data, cross
sections, data sheets, data summaries,
and field notes. Sketches, maps, and
permanent photo points can be used to
document vegetation development.
Videotape can be particularly useful to
document the performance of structures
during various flows, to illustrate
wildlife use and floodplain storage of
floodwaters, and otherwise to record
the performance and functions of the
corridor system.
Inspection reports are primarily in-
tended to address maintenance issues.
Problems discovered in the inspection
process should be documented in a re-
port that details deficiencies, recom-
mends specific maintenance, and
explains the consequences of not ad-
dressing the problems. Postplanting in-
spections to ensure survival require
documentation and immediate action.
Consequently, the reporting and re-
sponse loop should be simple and di-
rect so that inspections indicating the
need for emergency structural repairs
can be reported and resolved without
delay.
General Inspection
To the extent feasible, the entire stream
corridor should be inspected annually
to detect areas of rapid bank erosion
or debris accumulation (Figure 9.16).
A general inspection can also identify
inappropriate land uses, such as en-
croachments of roads near banks or
uncontrolled irrigation water returns,
that might jeopardize restoration mea-
sures, affect water quality, or otherwise
Table 9.2: Sample inspection schedule.
Time Since Installation I Inspection Interval
2 Months
6 Months
2 Years
2 weeks (4 total)
1 month (5 total)
6 months (3 total)
interfere with restoration objectives.
The integrity of fences, water access,
crossings, and other livestock control
measures should be inspected (Figure
9.17). Lack of compliance with agreed-
upon best management practices
should be noted as well. Aerial photos
are particularly useful in the overview
inspection, but inspections by boat or
on foot can be more informative in
many cases.
Bank and Channel Structures
Special inspections should be con-
ducted following high flows, particu-
larly after the first flood event following
installation. Soil bioengineering mea-
sures should be assessed during pro-
longed drought and immediately after
high flows during the first few years fol-
Figure 9.16: Flood debris. The entire corridor
should be inspected annually to detect areas of
debris accumulation from flood flows.
Restoration Implementation
9-23
-------
Figure 9.17: Fencing.
The integrity of
fencing should be
inspected periodi-
cally.
lowing installation until the system is
well established.
Most routine inspections of bank and
channel measures should be conducted
during low-water conditions to allow
viewing of the measure as well as chan-
nel bed changes that might threaten its
future integrity. This is particularly true
of bank stabilization works where the
principal mechanism of bank failure is
undermining at the toe. A low water in-
spection should involve looking for dis-
placed rock, settling or tilting,
undermining, and similar problems
(Johnson and Stypula 1993).
In the past, bank stabilization measures
were routinely cleared of vegetation to
facilitate inspection and prevent dam-
age such as displacement of rock by
trees uprooted from a revetment during
a flood. However, evidence that vegeta-
tion compromises revetment integrity
has not been documented (Shields
1987, 1988). Leaving vegetation in
place or planting vegetation through
rock blankets has been encouraged to
realize the environmental benefits of
vegetated streambanks. Consequently,
agencies have modified inspection and
maintenance guidelines accordingly in
some areas.
Vegetation
Streambanks that have been stabilized
using plantings alone or soil bioengi-
neering techniques require inspections,
especially in the first year or two after
planting (Figure 9.18). It is important
that the planted material be checked
frequently to ensure that the material is
alive and growing satisfactorily. Any
dead material should be replaced and
the cause of mortality determined and
corrected if possible. If the site requires
watering, rodent control, or other reme-
dial actions, the problem must be de-
tected and resolved immediately or the
damage may become severe enough to
require extensive or complete replant-
ing. Competition from weeds should be
noted if it is likely to suppress new
plantings. If nonnative plants capable
of invading and outcompeting native
species are known to be present in the
area, both plantings and existing native
vegetation should be inspected. Any
newly established nonnative popula-
tions should be eradicated quickly.
After the first growing season, semi-
annual to annual evaluations should be
sufficient in most cases. At the end of a
2-year period, 50 percent or more of the
originally installed plant material
should be healthy and growing well
(Figure 9.19). If not, determining the
cause of die-off and subsequent replant-
ing will probably be necessary. If the in-
stallation itself is determined to have
been improper, any warranty or dis-
pute-resolution clauses in the plant in-
stallation contract might need to be
invoked.
The effectiveness of bank protection is
based largely on the development of
the plants and their ability to bind soils
at moderate flow velocities. The bank
protection measures should be in-
spected immediately after high-flow
events in the first few years, particularly
9-24
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
if the plantings have not fully estab-
lished. Washouts, slumping of geogrids,
and similar problems require detection
and correction, since they might be-
come the sites of further deterioration
and complete failure if left uncorrected.
Floodplain and other off-channel plant-
ings might be important components of
the corridor restoration plan as well. In-
spection requirements are similar to
those on streambank sites but are less
critical to the integrity of the project in
terms of preventing additional damage.
Nevertheless, several site visits are ap-
propriate during the first growing sea-
son to detect problems due to
browsing, insects, too much or too little
water, and other causes. Inspection of
plantings that require irrigation during
establishment, as well as of the irriga-
tion system, may be needed on a
weekly or more frequent basis.
Techniques for inspecting vegetation
survival are fairly straightforward. Satis-
factory survival rates may be deter-
mined using stem counts within sample
plots or estimates of cover percentages,
depending on the purpose of the plant-
ings. For example, Johnson and Stypula
(1993) suggest that woody plantings es-
tablished for streambank protection
should not include open spaces more
than 2 feet in dimension. In most cases,
such criteria can be established in ad-
vance based on common-sense deci-
sions regarding the adequacy of
establishment relative to the objectives.
Where more detailed monitoring is ap-
propriate to document development of
habitat quality or similar objectives,
more rigorous monitoring techniques
can be used. (See Section 9.B).
Urban Features
Stream corridor objectives may require
periodic inspections of features other
than the stream, streambank, and corri-
dor vegetation. In urban areas, these
features may be a major focus of the in-
spection program. Facilities, nest boxes,
trails, roads, storm water systems, and
similar features must be inspected to
ensure they are in satisfactory condition
and are not contributing to degradation
of the stream corridor. Access points re-
quired to accomplish maintenance and
emergency repairs should be checked
for serviceability. Popular public use
areas, particularly stream access points,
should be evaluated to determine
Figure 9.18: Revege-
tation project. It is
important that the
planted material be
inspected frequently
to ensure that it is
alive and growing
satisfactorily.
Figure 9.19: Revegetation project, 1 to 2 years
postconstruction. At the end of a 2-year peri-
od, 50 percent or more of the original plant-
ings should be healthy and growing well.
Source: King County, Washington.
Restoration Implementation
9-25
-------
FAST
FORWARD
Preview Section
9.B, Monitoring
Techniques
Appropriate
for Evaluation
Restoration.
whether measures are being damaged,
erosion is being initiated, or project ob-
jectives are otherwise being impeded.
Inspection should reveal whether signs,
trail closures, and other traffic-control
measures are in place and effective.
Trash and debris dumping, off-road ve-
hicle damage, vandalism, and a wide
variety of other detrimental occurrences
may be noted during routine inspec-
tions.
Maintenance
Maintenance encompasses those repairs
to restoration measures which are based
on problems noted in annual inspec-
tions, are part of regularly scheduled
upkeep, or arise on an emergency basis.
Remedial maintenance is triggered by
the results of the annual inspection
(Figure 9.20). The inspection report
should identify and prioritize main-
tenance needs that are not emergen-
cies, but that are unlikely to be
addressed through normal scheduled
maintenance.
Scheduled maintenance is performed at
intervals that are preestablished dur-
ing the design phase or based on
project-specific needs. Such mainte-
nance activities as clearing culverts or
regrading roads can be anticipated,
scheduled, and funded well in
advance. In many instances, the
scheduled maintenance fund can be
a tempting source for emergency
funds, but this can result in neglect
of routine maintenance, which may
eventually produce a new, more cost-
ly, emergency.
Emergency maintenance requires
immediate mobilization to repair or
prevent damage. It may include mea-
sures such as replacement of plants
that fail to establish in a soil bioengi-
neered bank stabilization, or repair
of a failing revetment. Where there is
a reasonable probability that repair
or replacement might be required
(e.g., anything that depends on vege-
tation establishment), sources of
funding, labor, and materials should
be identified in advance as part of
the contingency planning process.
However, there should be some
general strategy for allowing rapid
response to any emergency.
Figure 9.20:
Remedial mainte-
nance. Soil bio-
engineering used
to repair failing
revetment.
9-26
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
Many maintenance actions will require
permits, and such requirements should
be identified well in advance to accom-
modate permitting delays. Similarly,
access to areas likely to require main-
tenance (e.g., bank stabilization struc-
tures) should be guaranteed at the time
of construction, and the serviceability
of access roads verified periodically.
Various agencies and utilities may have
maintenance responsibilities that in-
volve portions of the stream corridor,
such as road and transmission line
crossings. This work should be coordi-
nated as necessary to ensure there are
no conflicts with corridor objectives.
Channels and Floodplains
Corridor restoration that includes re-
configuration of the channel and flood-
plain may require remedial action if the
system does not perform as expected in
the first few years after work has been
completed. Any repairs or redesign,
however, should be based on a careful
analysis of the failure. Some readjust-
ment is to be expected, and a continu-
ing dynamic behavior is fundamental
to successful restoration. Because estab-
lishment of a dynamic equilibrium
condition is usually the intent, main-
tenance should be limited to actions
that promote self-sustainability
Many traditional channel maintenance
actions may be inappropriate in the
context of stream corridor restoration.
In particular, removal of woody debris
may be contrary to restoration objec-
tives (Figure 9.21). Appropriate levels
of woody debris loading should be a
design specification of the project, and
the decision to remove or reposition
particular pieces should be based on
specific concerns, such as unacceptably
accelerated bank erosion due to flow
deflection, creation of ice jams causing
an increased chance for flooding, or
concerns about safety in streams with
high recreational use. In cases where
woody debris sources have been de-
pleted, periodic addition of debris may
be a prescribed maintenance activity.
(See next page for story on engineered
log jams.)
Protection/Enhancement
Measures
Measures intended to enhance fish
habitat, deflect flows, or protect banks
are likely to require periodic mainte-
nance. If failure occurs soon after instal-
lation, the purpose and design of the
measure should be reevaluated before it
is repaired, and the mechanism of fail-
ure should be identified. Early failure is
an inherent risk of soil- bioengineered
systems that are not fully effective until
the plants are well rooted and the stems
reach a particular size and density. Al-
though a design weakness may be iden-
tifiable and should be corrected, more
often the mechanism of failure will be
that the measure has not yet developed
Figure 9.21: Accumulated woody debris.
Removal of woody debris may be contrary
to restoration objectives.
Restoration Implementation
9-27
-------
full resistance to high-flow velocities or
saturation of bank soils. Replanting
should be an anticipated potential
maintenance need in this situation.
In many stream corridor restoration
areas, the intent of streambank and
channel measures is to provide tempo-
rary stabilization until riparian vegeta-
tion develops and assumes those
functions. In such cases, maintenance of
some structures might become less im-
portant over time, and they might even-
tually be allowed to deteriorate. They
can be wholly or partially removed if
they represent impediments to natural
patterns of channel migration and con-
figuration, or if some components (ca-
bles, stone, geofabrics) become hazards.
Vegetation
Routine maintenance of vegetation in-
cludes removal of hazardous trees and
branches that threaten safety, buildings,
fences, and other structures, as well as
maintenance of vegetation along road
shoulders, trails, and similar features.
Planted vegetation may require irriga-
tion, fertilization, pest control, and sim-
ilar measures during the first few years
of establishment. In large-scale planting
efforts, such as floodplain reforestation
efforts, maintenance may be precluded.
Occasionally, replanting will be needed
because of theft.
Maintenance plans should anticipate
the need to replant in case soil- bio-
engineered bank protection structures
are subjected to prolonged high water
or drought before the plants are fully
established. Techniques using numer-
ous cuttings establish successfully, it
might be desirable to thin the dense
brush that develops to allow particular
trees to grow more rapidly, especially if
channel shading is a restoration objec-
tive. Often, bank protection measures
become popular points for people to
access the stream (for fishing, etc.).
Plantings can be physically removed or
trampled. Replanting, fencing, posting
signs, or taking other measures might
be needed.
Other Features
A wide variety of other restoration fea-
tures will require regular maintenance
or repair. Rural restoration efforts might
require regular maintenance and peri-
odic major repair or replacement of
fences and access roads for manage-
ment and fire control. Public use areas
and recreational facilities require up-
keep of roads, trails, drainage systems,
signs, and so forth (Figure 9.22). Main-
tenance of urban corridors may be in-
tensive, requiring trash removal,
lighting, and other steps. An adminis-
trative contact should be readily avail-
able to address problems as they
develop. As the level of public use in-
creases, contracting of maintenance ser-
vices might become necessary, and
administration of maintenance duties
will become an increasingly important
component of corridor management.
Restoration measures placed to benefit
fish and wildlife (e.g., nest boxes and
platforms, waterers) need annual clean-
ing and repair. These maintenance ac-
tivities can be as time-consuming as the
original installation, and structures that
are in bad condition might draw public
attention and criticism. The mainte-
nance commitment should be recog-
nized before such structures are
installed. Special wildlife management
units, such as moist-soil-management
impoundments and green-tree reser-
voirs, require close attention to be man-
aged effectively.
Flooding and drawdown schedules
must be fine-tuned based on site-
specific conditions (Fredrickson and
Taylor 1982). Special equipment might
be needed to maintain levees, to work
9-28
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
on soft ground, to repair drainage struc-
tures, and to pump out facilities, all of
which might incur substantial fuel
costs. The maintenance needs in these
kinds of situations require that profes-
sional resource managers be on site reg-
ularly. Not operating the restoration
attentively can create nuisance or haz-
ardous conditions, have severe detri-
mental effects on existing resources, and
fail to produce the desired results.
Mosquito control may also be a mainte-
nance concern near inhabited areas,
particularly if the restoration encour-
ages the development of slack-water
areas, such as beaver ponds, backwaters,
and floodplain depressions. In some
cases, control techniques may directly
interfere with restoration objectives, but
threats to people and livestock might
make them necessary.
Figure 9.22: Streamside trail. Public use areas
and recreational facilities require upkeep of
roads, trails, and signs.
9.B Monitoring Techniques Appropriate for
Evaluating Restoration
As discussed in Chapter 6, the comple-
tion of implementation does not mark
the end of the restoration process.
Restoration practitioners must plan for
and invest in the monitoring of stream
corridor restoration. The type and ex-
tent of monitoring will depend on spe-
cific management objectives developed
as a result of stream corridor characteri-
zation and condition analysis. Monitor-
ing may be conducted for a number of
different purposes including:
Performance evaluation: Assessed in
terms of project implementation and
ecological effectiveness. Ecological
relationships used in monitoring and
assessment are validated through col-
lection of field data.
Trend assessment: Includes longer term
sampling to evaluate changing eco-
logical conditions at various spatial
and temporal scales.
Risk assessment: Used to identify caus-
es and sources of impairment within
ecosystems.
Baseline characterization: Used to
quantify ecological processes operat-
ing in a particular area.
This section examines monitoring from
the perspective of evaluating the perfor-
mance of a restoration initiative. Such
initiatives seek to restore the structure
and functions discussed in earlier chap-
ters. Designing a monitoring program
that directly relates to those valued
functions requires careful planning to
ensure that a sufficient amount of infor-
mation is collected. Such monitoring
uses measurements of physical, biologi-
cal, and chemical parameters to evalu-
Review previ-
ous chapters
for an introduc-
tion to the
restoration of
stream corridor
structure and
functions.
Restoration Implementation
9-29
-------
CASESnjDY Engineered Log Jams for Bank
^^^ ^^T ^^ Prrvtartirm anrl Uahi+at Roctrkr;
/^
Protection and Habitat Restoration
Mosf riverbank protection measures are
not designed to improve aquatic or
riparian habitat, and many restoration initiatives
lack sufficient engineering and geomorphic
analysis to effectively restore natural functions
of riparian and aquatic ecosystems. The ecolog-
ical importance of instream woody debris (WD)
has been well documented. Woody debris with-
in a stream can often influence the instream
channel structure by increasing the occurrence
of pools and riffles. As a result, streams with
WD typically have less erosion, slower routing
of organic detritus (the main food source for
aquatic invertebrates), and greater habitat
diversity than straight, even-gradient streams
with no debris. Woody debris also provides
habitat cover for aquatic species and character-
istics ideally suited for fish spawning.
Reintroduction of WD (or logjams) in many
parts of the United States has been extensive,
but limited understanding of WD stability has
hampered many of these efforts. Engineered log
jams (EUs) can restore riverine habitat and in
some situations can provide effective bank pro-
tection (Figure 9.23). Although WD is often
considered a hazard because of its apparent
mobility, research in Olympic National Park has
documented that stable WD jams can occur
throughout a drainage basin (Abbe et al. 1997).
Even in large alluvial channels that migrate at
rates of 30 ft./yr, jams can persist for centuries,
creating a mosaic of stable sites that in turn
host the large trees necessary to initiate stable
jams. Engineered log jams are designed to emu-
late natural jams and can meet management or
restoration objectives such as bank protection
and debris retention.
After learning about the uncertainty and poten-
tial risks of creating man-made logjams,
landowners near Packwood, Washington, decid-
ed the potential environmental, economic, and
aesthetic benefits outweighed the risks. An
experimental project consisting of three EUs
was implemented to control severe erosion
along 1,400 ft. of the upper Cowlitz River. The
channel at the site was 645 ft. wide and had
an average bank erosion rate of 50 ft./yr from
1990 to 1995. Five weeks after constructing the
logjams, the project experienced a 20-year
recurrence flow (30,000 ft3Is). Each EU
remained intact and met design objectives by
transforming an eroding shoreline into a local
depositional environment (i.e., accreting shore-
line). Approximately 93 tons of WD that was
in transport during the flood was trapped by the
EUs, alleviating downstream hazards and
enhancing structure stability. Improvements in
physical habitat included creation of complex
scour pools at each EU (Abbe et al. 1997).
Landowners have been delighted by the experi-
ment. The EUs have remained intact, increased
in size, and reclaimed some of the formerly
eroded property even after being subjected to
major floods in February 1996 and March
1997. When compared to traditional bank
stabilization methods, which typically employ
the extensive use of exotic materials such as
rock rarely found in low-gradient alluvial chan-
nels, EUs can offer an effective and low-cost
alternative for erosion control, flood control,
and habitat enhancement. The cumulative
effect of most traditional bank stabilization
methods over time results in progressive chan-
nel confinement and detachment of the ripari-
an environment from the channel (e.g., loss of
streamside vegetation). In stark contrast, the
cumulative effects of using EUs include long-
term protection of a significant flood plain,
improvement of instream and riparian habitat,
and bank stabilization (Abbe et al. 1997).
9-30
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
Comprehensive geomorphic and hydraulic
engineering analysis is required to deter-
mine the type of WD needed and the
appropriate size, position, spacing, and
type of ELJ structure for the particular
site(s) and project objectives. Inappropriate
design and application of ELJs can result in
negative impacts such as local accelerated
bank erosion, unstable debris, or channel
avulsion. Acknowledging the potential risks
and uncertainties of ELJs, their use should
be limited to well-documented experimen-
tal situations. Continued research and
development of ELJs involving field applica-
tion in a variety of physiographic and cli-
matic conditions is needed. ELJs can pro-
vide a means to meet numerous objectives
in the management and restoration of
rivers and riparian corridors throughout the
United States.
Figure 9.23:
Engineered log jams.
Engineered log jams
(ELJs) can restore
riverine habitat and
in some situations
provide effective
bank protection.
Restoration Implementation
9-31
-------
Review Chapter
7D's section on
analytical
methods for
evaluating
biological
attributes.
Adaptive
management
provides the
opportunity
for course cor-
rection through
evaluation and
action.
ate the effectiveness of the restoration
and to facilitate adaptive management
where needed. Sampling locations,
measurements to be made, techniques
to be used, and how the results will be
analyzed are important considerations
in monitoring.
Adaptive Management
The implementation, effectiveness, and
validation components of performance
monitoring provide a vehicle to deter-
mine the need for adaptive manage-
ment. Adaptive management is the
process of establishing checkpoints to
determine whether proper actions have
been taken and are effective in provid-
ing desired results. Adaptive manage-
ment provides the opportunity for
course correction through evaluation
and action.
Implementation Monitoring
Implementation monitoring answers the
question, "Were restoration measures
done and done correctly?" Evaluating
the effectiveness of restoration through
physical, biological, and/or chemical
monitoring can be time-consuming,
expensive, and technically challenging.
Time and partnerships are needed to
build the capability for evaluating pro-
ject effectiveness based on changes in
ecological condition. Therefore, an
important interim step to this goal is
implementation monitoring. This com-
paratively simple process of document-
ing what was done and whether or not
it was done properly can yield valuable
information that promotes refinement
of restoration practices.
Effectiveness Monitoring
Effective monitoring answers the ques-
tion "Did restoration measures achieve
the desired results?" or more simply
"Did the restoration initiative work?"
Effectiveness monitoring evaluates suc-
cess by determining whether the
restoration had the desired effect on the
ecosystem. Monitoring variables focus
on indicators that document achieve-
ment of desired conditions and are
closely linked with project goals. It is
important that indicators selected for
effectiveness monitoring are sensitive
enough to show change, are measur-
able, are detectable and have statistical
validity. This level of monitoring is
more time-consuming than implemen-
tation monitoring, making it more
costly. To save time and money, moni-
toring at this level is usually performed
on a sample population or portion of a
project with results extrapolated to the
whole population.
Validation Monitoring
Validation monitoring answers the
question "Are the assumptions used in
restoration design and cause-effect rela-
tionships correct?" Validation monitor-
ing considers assumptions made during
planning and execution of restoration
measures. This level of monitoring is
performed in response to nonachieve-
ment of desired results once proper
implementation is confirmed. A res-
toration initiative that fails to achieve
intended results could be the result of
improper assumptions relative to eco-
logical conditions or selection of in-
valid monitoring indicators. This level
of monitoring is always costly and re-
quires scientific expertise.
Evaluation Parameters
Physical Parameters
A variety of channel measurements are
appropriate for performance evaluation
(Figure 9.24). The parameters pre-
sented in Table 9.3 should be consid-
ered for measurement of physical
performance and stability. Stream pat-
tern and morphology are a result of the
9-32
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
interaction of eight measurable parame-
terswidth, depth, channel slope,
roughness of channel materials, dis-
charge, velocity, sediment loads, and
sediment size (Leopold et al. 1964).
These parameters and several other di-
mensionless ratios (including entrench-
ment, width/depth ratio, sinuosity, and
meander/width ratio) can be used to
group stream systems with similar form
and pattern. They have been used as
delineative criteria in stream classifica-
tion (Rosgen 1996). Natural streams are
not random in their variation.
A change in any of the primary stream
variables results in a series of channel
adjustments, resulting in alterations of
channel pattern and form, and atten-
dant changes in riparian and aquatic
habitat.
Biological Parameters
Biological monitoring can cover a broad
range of organisms, riparian conditions,
and sampling techniques. In most cases,
budget and staff will limit the diversity
and intensity of evaluation methods
chosen. Analytical methods for evaluat-
ing biological attributes are discussed in
Section 7.D of this document.
Table 9.4 provides examples of the bio-
logical attributes of stream ecosystems
that may be related to restoration goals.
Biological aspects of the stream corridor
that may be monitored as part of per-
formance goals include primary pro-
ductivity, invertebrate and fish
communities, riparian/terrestrial
wildlife, and riparian vegetation. This
may involve monitoring habitat or
fauna to determine the degree of suc-
cess of revegetation efforts or instream
habitat improvements.
Biological monitoring programs can in-
clude the use of chemical measures. For
example, if specific stressors within the
REVERSE
Figure 9.24: Measurement of a stream corridor.
Monitoring the physical aspects of the stream
corridor system is important in evaluating the
success of any restoration effort.
stream system, such as high water tem-
peratures and low dissolved oxygen,
limit biological communities, direct
monitoring of these attributes can pro-
vide an evaluation of the performance
of more intensive remedial practices, in-
cluding point source pollution reduc-
tion.
Chemical Parameters
Monitoring is necessary to determine if
a restoration initiative has had the de-
sired effect on water chemistry. The type
and extent of chemical monitoring de-
pends upon the goal of the monitoring
program. Major chemical parameters of
water and their sampling are discussed
in Chapters 2 and 7.
A factor in designing a chemical moni-
toring approach is the amount of
change expected in a system. If the
Review Chap-
ters 2 and 7 for
information on
chemical water
parameters and
their sampling.
Also, review
Chapter 8's sec-
tion on refer-
ence reaches.
Monitoring Techniques Appropriate for Evaluating Restoration
9-33
-------
Table 9.3: Physical parameters to be considered in establishing evaluation criteria for measure-
ment of physical performance and stability.
Plan view
Cross sectional profiles by reach
and features
Longitudinal profile
Classification of existing
streams (all reaches)
Assessment of hydrologic flow
regimes through monitoring
Channel evolutionary
track determination
Corresponding riparian
conditions
Corresponding watershed
trends-past 20 years and future
20 years
Sinuosity, width, bars, riffles, pools, boulders, logs
Sketch of full cross section
Bank response angle
Depth bankfull
Width
Width/depth ratio
Bed particle size distribution
Water surface slope
Bed slope
Pool size/shape/profile
Riffle size/shape/profile
Bar features
Varies with classification system
2-, 5-, 10-year storm hydrographs
Discharge and velocity of base flow
Decreased or increased runoff, flash flood flows
Incisement/degradation
Overwidening/aggradation
Sinuosity trendevolutionary state, lateral migration
Increasing or decreasing sinuosity
Bank erosion patterns
Saturated or ponded riparian terraces
Alluvium terraces and fluvial levees
upland/well-drained/sloped or terraced geomorphology
Riparian vegetation composition, community patterns and
successional changes
Land use/land cover
Land management
Soil types
Topography
Regional climate/weather
restoration goal, for example, is to re-
duce the salinity in a stream by 5 per-
cent, it would be much more difficult
to detect than a goal of reducing salin-
ity by 50 percent.
Chemical monitoring can often be used
in conjunction with biological monitor-
ing. There are pros and cons for using
chemical and biological parameters
when monitoring. Biological parame-
ters are often good integrators of several
water quality parameters. Biological in-
dicators are especially useful when de-
termining the bioaccumulation of a
chemical.
Water chemistry samples are typically
easier to replicate, can disclose slow
changes over time, and be used to pre-
vent catastrophic events when chemical
characteristics are near toxic levels. For
example, water quality monitoring
might detect a slow decrease in pH over
a period of time. Some aquatic organ-
isms, such as trout, might not respond
9-34
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
to this gradual change until the water
becomes toxic. However, water quality
monitoring could detect the change
and thereby avoid a catastrophic event.
An ideal monitoring program would
include both biological and chemical
parameters.
Important chemical and physical para-
meters that might have a significant in-
fluence on biological systems include
the following:
Temperature
Turbidity
Dissolved oxygen
pH
Natural toxics (mercury) and manu-
factured toxics
Flow
Nutrients
Organic loading (BOD, TOG, etc.)
Alkalinity/Acidity
Hardness
Dissolved and suspended solids
Channel characteristics
Spawning gravel
Instream cover
Shade
Pool/riffle ratio
Springs and ground water seeps
Bed material load
Amount and size distribution of
large woody debris (i.e., fallen trees)
These parameters may be studied inde-
pendently or in conjunction with bio-
logical measurements of the ecological
community.
Reference Sites
Understanding the process of change re-
quires periodic monitoring and mea-
Table 9.4: Examples of biological attributes
and corresponding parameters that may be
related to restoration goals and monitored as
part of performance evaluation.
Biological
Attribute
Primary
productivity
Parameter
Periphyton
Plankton
Vascular and nonvascular
macrophytes
Invertebrate
community
Zooplankton/diatoms
Species
Numbers
Diversity
Biomass
Macro/micro
Fish
community
Aquatic/terrestrial
Anadromous and resident species
Specific populations or life stages
Number of outmigrating smolts
Number of returning adults
Riparian wildlife/ Amphibians/reptiles
terrestrial
community Mammals
Birds
Riparian
vegetation
Structure
Composition
Condition
Function
Changes in time (succession,
colonization, extirpation, etc.)
surement and scientific interpretation
of the information as it relates to the
stream corridor. In turn, an evaluation
of the amount of change attributed to
restoration must be based on estab-
lished reference conditions developed
by the monitoring of reference sites.
The following are important considera-
tions in reference site selection:
What do we want to know about the
stream corridor?
Are identified sites minimally-
disturbed?
Are the identified sites representative
of a given ecological region, and do
they reflect the range of natural vari-
Monitoring Techniques Appropriate for Evaluating Restoration
9-35
-------
Performance Evaluation of Fish Barrier Modifications
Fish barrier modifications provide a good example
of a technically difficult performance evaluation.
The goal of the restoration is easily understood
and stated. Barrier modification provides one of
two optionsto increase populations (increase
upstream and downstream movement) or to
decrease populations (restrict movement).
In all cases, the specific target species should be
identified. If the goal is to restore historic runs of
commercial fishes, data for commercial landings
may be available to provide guidance. Habitat
models are available for species such as Atlantic
salmon and can provide insight into expected
carrying capacities of nursery habitat. Existing runs
in adjacent or nearby river(s) may be examined for
population levels and trends that can provide
insight into realistic goals. Barriers may be planned
for only short-term protect/on of some species
(e.g., protection against cannibalism) or for longer
term exclusion of problematic or undesirable
species.
Methodologies to evaluate the success of fish bar-
rier modifications can use a variety of field meth-
ods to count the number of adult spawners, to
determine the abundance of fry, to estimate the
size of the outmigrating juvenile population, or to
monitor the travel time between specific points
within a watershed (Table 9.5). However, consider-
ation needs to be given to factors that may influ-
ence the success of the population outside the
study area. Commercial fishing, disease, predation,
limited food supply, or carrying capacity of juvenile
or adult habitat may be more important control-
ling factors than access to spawning and nursery
habitat.
The performance evaluation must allow ample
time for the species to complete its life cycle. Many
anadromous species have life spans of 4 to 7
Table 9.5: Methods to evaluate effectiveness of
fish barrier modifications.
Modification
Method
Population
estimates
Fishway counts Observation windows
Hydroacoustics
Fish traps/weirs
Netting
Mark and recapture
Snorkel counts
Redd counts
Creel census
Direct counts of spawning adults
Radio tagging
Pit tags
Timing of
migration
between
observation
points
Dyes and other external marks
Computer-coded tags
years; sturgeon live for decades. Adequate homing
to natal areas may require several generations to
build a significant migrating population and to fill
all year classes. Floods or droughts can impact fry
and juvenile life stages and do not become appar-
ent in adult spawning populations until several
years have elapsed. Restoration and monitoring
goals need to be formulated to take these non-
restoration-limiting factors into account.
Examination of year-class structure of returning
adults might be useful, or investigations that aver-
age the size of spawning runs for multiple years
might be appropriate.
Performance evaluation study methodologies must
use appropriate monitoring techniques. Collecting
techniques need to be relatively nondestructive.
Collecting weirs, traps, or nets need to be
designed to limit injury or predation and should
function over a wide range of flow and debris lev-
els. Monitoring techniques should not extensively
9-36
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
limit movement. Weirs and traps should not cause
excessive delays in migration, and fish tags should
not encumber movement. Techniques are often
species- and life stage-specific. Fish tags, including
radio tags, may be appropriate for older, larger
individuals, whereas chemical marks, dyes, fin
clips, or internal microtags may be appropriate
for smaller organisms. Certain fish, such as alosids
(American shad and river herring), may be more
difficult to handle than others, such as salmonids
(trout and salmon), and appropriate handling
techniques need to be used. Avoiding extreme
environmental conditions (excessively high or low
water temperature or flow) may be important.
Nondestructive techniques, such as hydroacousitics
and radio tags, have several advantages, but care
needs to be taken to differentiate between back-
ground noise (mechanical, debris, entrained air,
nonlaminar flow), other species, and target
species.
Monitoring Techniques Appropriate for Evaluating Restoration
9-37
-------
Many human
interest-oriented
criteria used in
performance
evaluations can
serve the dual
function of
evaluating
elements of
human use and
ecological con-
dition together.
ability associated with a given stream
class?
What is the least number of sites
required to establish reference
conditions?
What are the impediments to refer-
ence site access?
Reference sites provide examples of a
properly functioning ecosystem. It is
from these reference sites that desired
conditions are determined and levels of
environmental indicators identified. En-
vironmental indicators become the per-
formance criteria to monitor the success
of a initiative.
Human Interest Factors
Human activities requiring use of a
healthy environment may often be im-
portant factors for evaluating stream
corridor restorations (Figure 9.25). In
these cases, the ability of the stream
corridor to support the activity indicates
benefits drawn from the stream corridor
as well as adding insight into stream
ecosystem condition. Many human in-
terest-oriented criteria used in perfor-
mance evaluations can serve the dual
function of evaluating elements of
human use and ecological condition
together:
Figure 9.25: Human interest in the stream corridor. Aesthetics are a highly valued benefit
associated with a healthy stream corridor.
9-38
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
Additional References for Monitoring
Averett, R.C., and L.J. Schroder. 1993. A guide to the design of surface-water-quality
studies: US Geological Survey Open-File Report 93-105, U.S. Geological Survey.
Karr, J.R., and W. Chu. 1997. Biological monitoring and assessment: Using Multimetric
Indexes Effectively. USEPA 235-R97-001. University of Washington, Seattle.
Kerchner, J.L 1997. Setting Riparian/Aquatic Restoration Objectives Within a Watershed
Context. In Restoration Ecology Vol. 5, No. 45.
Manley, PA., et al. 1995. Sustaining Ecosystems: A Conceptual Framework. USDA
Forest Service, Pacific Southwest Region, San Francisco, CA. 216 pp.
McDonald, L.H., eta/. 7997. Monitoring Guidelines to Evaluate Effects of Forestry
Activities on Streams in the Pacific Northwest and Alaska. USEPA, Region 10, Seattle,
WA. 166pp.
Sanders, T.G., R.C. Ward, J.C. Loftis, ID. Stee/e, D.D. Adrian, and V. Yevjevich. 1983,
Design of networks for monitoring water quality. Water Resources Publications,
Littleton, CO., 328 p.
Stednick, J.D. 1991. Wild/and water quality sampling and analysis. Academic Press,
San Diego.
Ward, R.C., J.C. Loftis, and G.B. McBride. 1990. Design of water quality monitoring
systems. Van Nostrand Reinhold, New York.
Human health (disease, toxic/fish
consumption advisories)
Aesthetics (odor, views, sound, litter)
Non-consumptive recreation (hiking,
birding, Whitewater rafting, canoeing,
outdoor photography)
Consumptive recreation (fishing,
hunting)
Research and educational uses
Protection of property (erosion con-
trol, floodwater retention)
Use surveys, which determine the suc-
cess of the restoration in terms of
human use, can provide additional bio-
logical data. Angler survey, creel census,
birding questionnaires, and sign-in trail
boxes that request observations of spe-
cific species can also provide biological
data. Citizens' groups can participate ef-
fectively, providing valuable assistance
at minimal cost.
Monitoring Techniques Appropriate for Evaluating Restoration
9-39
-------
9.C Restoration Management
Management
needs can
range from rel-
atively passive
approaches that
involve removal
of acute impacts
to intensive
efforts designed
to restore
ecosystem func-
tions through
active inter-
vention.
Management is the long-term manipu-
lation and protection of restoration re-
sources to achieve objectives.
Management priorities for the stream
corridor ecosystem are set during the
planning phase and refined during de-
sign. These priorities should also be
subject to ongoing revision based on
regular monitoring and analysis. Man-
agement needs can range from rela-
tively passive approaches that involve
removal of acute impacts to intensive
efforts designed to restore ecosystem
functions through active intervention.
Whereas a preceding section described
the need to provide adequate mainte-
nance for the restoration elements,
restoration management is the collec-
tive set of decisions made to guide the
entire restoration effort to success.
The restoration setting and the priori-
ties of participants can make manage-
ment a fairly straightforward process or
a complex process that involves numer-
ous agencies, landowners, and inter-
ested citizens. Development of a
management plan is less difficult when
the corridor and watershed are under
the control of a single owner or agency
that can clearly state objectives and pri-
orities. Some stream corridor restora-
tions have, in fact, involved extensive
land acquisition to achieve sufficient
management control to make restora-
tion feasible. Even then, competing in-
terests can exist. Decisions must be
made regarding which resource uses are
compatible with the defined objectives.
More commonly, stream corridor man-
agement decisions will be made in an
environment of conflicting interests,
overlapping mandates and regulatory
jurisdictions, and complex ownership
patterns, both in the corridor and in the
surrounding watershed. For example, in
a Charles River corridor project in Mass-
achusetts, the complex ownership pat-
tern along the river requires direct
active management in some areas and
easements in others. In the remainder,
management is largely a matter of en-
couraging appropriate use (Barron
1989). Many smaller restorations might
be similarly diversified with manage-
ment decisions involving a variety of
participants. Participation and adher-
ence to restoration best management
practices (BMPs) may be encouraged
through various programs, such as the
NRCS's Conservation Reserve Program,
multi-agency riparian buffer restoration
initiatives, and cost-sharing opportuni-
ties available under the EPA Section 319
Program.
Programs intended to reduce nonpoint
source pollution of waterways often
encourage the use of practices to ad-
dress problems such as agricultural
runoff or sediment generated by timber
harvest operations. Because many prac-
tices focus on activities within the
stream corridor, existing practices
should be reviewed to determine their
applicability to the stream corridor
restoration plan (Figure 9.26). Al-
though the ecological restoration objec-
tives for the corridor might require
more restrictive management, existing
practices can provide a good starting
point and establish a rationale for mini-
mum management prescriptions. In
stream corridor restoration efforts in-
volving numerous landowners, it might
be appropriate to develop a revised set
of practices specific to the restoration
area. Participants should have the op-
portunity to participate in developing
the practices and should be willing to
commit to compliance before the
restoration is implemented.
9-40
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
Regulatory controls influencing man-
agement options are increasingly com-
plex and require regular review as
management plans evolve and adapt. In
some areas, regulatory oversight of ac-
tivities in streamside areas and in the
vicinity of wetlands involves fairly rigid
rules that may conflict with specific
proposed management actions (e.g., se-
lective tree removals). Implementation
of management actions in such cases
will require coordination and approval
from the regulating agencies. Many state
and local jurisdictions vary their restric-
tions according to classification systems
reflecting the condition of the stream-
side area or wetland in terms of "natu-
ralness"; for example, sites with large
trees might receive a higher level of pro-
tection than sites that have been heavily
disturbed.
Restoration is intended specifically to
improve the condition of the stream
corridor; however, an activity that is al-
lowable initially might be regulated as
the corridor condition improves. These
changes should be anticipated to the
extent possible in developing long-term
management and use plans.
In effect, stream corridor restoration
and ongoing monitoring constitute
stream management. Many problems
detected during monitoring can be re-
solved by manipulation of the stream
corridor vegetation (Figure 9.27), land
uses, where possible, and only occa-
sionally, by direct physical manipula-
tion of the channel. If "resetting" of the
channel system is necessary, it essen-
tially becomes a redesign problem.
Where lateral erosion occurs in unantic-
ipated areas and poses an unacceptable
threat to function, property, or infra-
structure, another restoration approach
might have to be initiated.
Figure 9.26: Livestock fences used as a BMP. Reviewing existing BMPs
can be useful in establishing management prescriptions.
Figure 9.27: Pruning streamside vegetation. Monitoring might detect
the need for manipulation of streamside vegetation.
-------
In cases where streamflow control is an
option, it likely will be a significant
component of the management plan to
maintain baseflows, water temperatures,
and other attributes. However, appro-
priate flow patterns should have been
defined during the design phase, with
components of corridor management
prescribed accordingly. If hydrologic
patterns change after the restoration is
established, significant redesign or
management changes might be required
for the entire corridor. Ultimately, a
well-planned, prepared stream corridor
restoration design predicts and ad-
dresses the potential for hydrologic
change.
Forests
In forested environments, the planning
and design phases of stream corridor
restoration should set specific objectives
for forest structure and composition
within the corridor. If existing forests
are developing in the desired direction,
action may not be needed. In this case,
forest management consists of protec-
tion rather than intervention. In de-
graded stream corridor forests,
achieving desired goals requires active
forest management. In many corridors
economic return to private and public
landowners is an important objective of
the restoration plan. Stream corridor
restoration may accommodate eco-
nomic returns from forest management,
but management within the stream cor-
ridor should be driven primarily by eco-
logical objectives. If the basic goal is to
restore and maintain ecological func-
tions, silviculture should imitate natural
processes that normally occur in the
corridor.
Numerous forest management activities
can promote ecological objectives. For
example, some corridor forest types
might benefit from prescribed fire or
wildfire management programs that
maintain natural patterns of structural
and compositional diversity and regen-
eration. In other systems, fire might be
inappropriate or might be precluded if
the stream corridor is in an urban set-
ting. In the latter case, silvicultural treat-
ments might be needed to emulate the
effects of fire.
Recovery of degraded streamside forests
can be encouraged and accelerated
through silvicultural efforts. Active in-
tervention and management may be es-
sential to maintain the character of
native plant communities where river
regulation has contributed to hydrology
and sedimentation patterns that result
in isolation from seed sources (Klimas
1991, Johnson 1994). Streamside
forests used as buffers to prevent nutri-
ents from reaching streams may require
periodic harvests to remove biomass
and maintain net uptake (Lowrance et
al. 1984, Welsch 1991). However,
buffers intended to intercept and de-
grade herbicides might be most effec-
tive if they are managed to achieve
old-growth conditions (Entry et al.
1995).
Management of corridor forests should
not proceed in isolation from manage-
ment of adjacent upland systems (Fig-
ure 9.28). Upland harvests can result in
raised water tables and tree mortality in
riparian zones. Coordinated silvicul-
tural activities can reduce timber losses
as well as minimize the need for roads
(Oliver and Hinckley 1987).
Forests managed by government agen-
cies are usually subject to established
restrictions on activities in riparian
areas. Elsewhere, BMPs for forestry prac-
tices are designed to minimize non-
point source pollution and protect
water quality. BMPs typically include re-
strictions on road placement, equip-
ment use, timber removal practices, and
other similar considerations. Existing
9-42
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
Figure 9.28: Streamside forests and adjacent
uplands. Management of streamside forests
should not proceed in isolation from manage-
ment of adjacent upland systems.
state BMP guidelines may be appropri-
ate for application within the restora-
tion area but often require some
modification to reflect the objectives of
the restoration or other pre-identified
constraints on activities in the vicinity
of streams and wetlands.
Grazed Lands
Livestock grazing is a very important
stream corridor management issue in
most nonforested rangelands and in
many forested areas. Uncontrolled live-
stock grazing can have severe detrimen-
tal effects on streambanks, riparian
vegetation, and water quality, particu-
larly in arid and semiarid environ-
ments (Behnke and Raleigh 1978,
Elmore and Beschta 1987, Chaney et
al. 1990) (Figure 9.29). Livestock natu-
rally concentrate in the vicinity of
streams; therefore, special efforts must
be made to control or prevent access if
stream corridor restoration is to be
achieved.
In some cases, livestock may act as an
agent in restoration. Management of
livestock access is critical to ensure
their role is a positive one. Existing
state BMPs might be sufficient to pro-
mote proper grazing, but might not be
innovative or adaptive enough to meet
the restoration objectives of a corridor
management program.
Complete exclusion of livestock is an
effective approach to restore and main-
tain riparian zones that have been
badly degraded by grazing. In some
cases, exclusion may be sufficient to re-
verse the damage without additional in-
tervention. In some degraded systems,
removal of livestock for a period of
years followed by a planned manage-
ment program may allow recovery with-
Figure 9.29: Livestock
in stream. Uncontrolled
livestock grazing can
have severe detrimental
effects on streambanks,
riparian vegetation, and
water quality.
Restoration Management
9-43
-------
CASESTUDY Partners Working for the Big Spring
^^ y*? ^^ rvt*t*lf lAla+AHeUArl
Creek Watershed
The Big Spring Creek watershed occupies a
diverse, primarily agricultural landscape in cen-
tral Montana, where the nation's third largest
freshwater spring (Big Springs) provides untreated
drinking water for the 7,000 residents of
Lewistown and is the source of one of Montana's
best trout streams, Big Spring Creek.
Conservation work by federal, state, and local
agencies, private organizations, and citizens in the
255,000-acre Big Spring Creek watershed is not
new. Actually, various projects and developments
have occurred over the last several decades. For
example, the flood control project that protects
the city of Lewistown has its roots in the 1960s
when, after experiencing a series of floods, the city
of Lewistown and community leaders decided to
take action. The Fergus County Conservation
District, Fergus County Commissioners, City of
Lewistown, U.S. Natural Resources Conservation
Service, and many community leaders all worked
together on this project. The Big Spring Creek
Flood Control Project now protects the city of
Lewistown from recurrent flooding.
Conservation work now, though, goes beyond
flood control. It involves working to solve resource
problems on a watershed basis, recognizing that
what happens upstream has an effect on the
downstream resources. We should look beyond
property boundaries at the whole watershed, con-
sidering the "cumulative effects" of all our actions.
With that in mind, the Fergus County Conservation
District, with assistance from its citizen committee,
has been working the last few years to improve
and protect the watershed. With funding from the
Montana Department of Environmental Quality
(Section 319), the Big Spring Creek Watershed
Partnership was formed.
This project helps agricultural producers and other
landowners to plan and install conservation prac-
tices to prevent erosion and keep sediment and
other pollutants out of streams and lakes. Area
landowners are implementing conservation prac-
tices such as improving the riparian vegetation
(Figure 9.30), treating streambank erosion, and
developing water sources off the stream for live-
stock. Because the project has been well received
by the agricultural producers, it has been possible
for cooperating agencies to participate in addition-
al watershed improvements. The U.S. Fish and
Wildlife Service Partners for Wildlife program has
provided funding for several stream restoration
and riparian improvement projects. In addition, the
Montana Department of Fish, Wildlife and Parks is
actively participating in fisheries habitat projects,
including the Brewery Flats Stream Restoration.
Implementation of the Big Spring Creek Watershed
Partnership has brought many positive changes to
the predominantly agricultural Big Spring Creek
watershed. Since most of the agricultural opera-
tions are livestock or grain, the major emphasis is
on riparian/stream improvement and grazing man-
agement. Thus far, more than 30 landowners have
participated in the project by installing conservation
practices that include over 8 miles of fencing, and
13 off-stream water developments, with more
than 10 miles of stream/riparian area protected.
Studies show that stream characteristics and water
quality are the best indicators of watershed vitality.
Thus, an active monitoring strategy in the water-
shed provides feedback to measure any improve-
ments. Preproject and postproject fisheries (trout)
surveys are conducted in cooperation with the
Montana Department of Fish, Wildlife and Parks
on selected streams. On East Fork Spring Creek,
fencing and off-stream water development were
implemented on a riparian/stream reach that was
severely degraded from livestock use. Fish popula-
tions and size structure changed dramatically from
preproject to postproject work. Salmonid numbers
increased from 12 to 32 per 1,000 feet, and aver-
age size increased by 50 percent. In addition to
9-44
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
fisheries surveys, benthic macroinvertebrate com-
munities are collected and analyzed on a number
of streams. This analysis relates to the stream's bio-
logical health or integrity. Community structure,
function, and sensitivity to impact are compared to
baseline data. Habitat conditions on three of six
monitoring sites on Big Spring Creek from 1990 to
1997 have shown improved conditions from a sub-
optimal to an optimal rating. Monitoring will con-
tinue on major streams in the watershed, which
will help to provide important feedback as to the
project's effectiveness.
Although the major emphasis is on improving and
protecting the riparian areas and streams in the
watershed, other ongoing efforts include partic-
ipating in the "Managing Community Growth" ini-
tiative, preserving agriculture and open space, and
developing recreational and environmental
resources. An active committee of the group is
involved in one of the largest stream restoration
initiatives ever to be undertaken in Montana,
planned for 1998. Included in this project is an
environmental education trial site being developed
with the local schools.
Working with watersheds is a dynamic process,
and as a result new activities and partners are con-
tinually incorporated into the Big Spring Creek
Watershed Partnership. The following agencies and
organizations are currently working together with
the citizens of the watershed to protect this "very
special place."
Fergus County Conservation District
M.S.U.-Extension Service, Fergus County
U.S. Natural Resources Conservation Service
U.S. Fish and Wildlife Service
Montana Department of Fish, Wildlife and Parks
Montana Department of Environmental Quality
Montana Department of Natural Resources and
Conservation
MM
Figure 9.30: The Big Spring Creek watershed, (a) A heavily
impacted tributary within the Big Spring Creek watershed
and (b) the same tributary after restoration.
U.S. Forest Service
City Of Lewistown
Fergus County Commissioners
Snowy Mountain Chapter Trout Unlimited
Central Montana Pheasants Forever
Lewistown School District No. 1
Lewistown Visioning Group
Lewistown Area Chamber of Commerce
Restoration Management
9-45
-------
Corridors that
include grazing
or have live-
stock in adja-
cent areas
require vigi-
lance to ensure
that fences are
maintained
and herd man-
agement BMPs
are followed.
out permanent livestock exclusion (El-
more and Beschta 1987). Systems not
badly damaged might respond to graz-
ing management involving seasonal
and herd size restrictions, off-channel
or restricted-access watering, use of ri-
parian pastures, herding, and similar
techniques (Chaney et al. 1990). Re-
sponse to grazing is specific to channel
types and season.
In off-channel areas of the stream corri-
dor, grazing may require less intensive
management. Grazing might have lim-
ited potential to be used as a habitat
manipulation tool in certain ecosys-
tems, such as the Northern Plains,
where native grazing animals formerly
controlled ecosystem structure (Sever-
son 1990). However, where grazing oc-
curs within the stream corridor, it might
conflict directly with ecosystem restora-
tion objectives if not properly managed.
Corridors that include grazing or have
livestock in adjacent areas require vigi-
lance to ensure that fences are main-
tained and herd management BMPs are
followed.
Fish and Wildlife
Stream and vegetation care are the focus
of many fish and wildlife management
activities in the stream corridor. Hunt-
ing and fishing activities (Figure 9.31),
nuisance animal control, and protec-
tion of particular species may be ad-
dressed in some restoration plans.
Special management units, such as sea-
sonally flooded impoundments specifi-
cally designed to benefit particular
groups of species (Fredrickson and Tay-
lor 1982), might be appropriate com-
ponents of the stream corridor,
requiring special maintenance and
management. Numerous fish and
wildlife management tools and tech-
niques that address temporary defi-
ciencies in habitat availability are
available (e.g., Martin 1986). Inappro-
priate or haphazard use of some tech-
niques can have unintended
detrimental effects (for example, plac-
ing wood duck nest boxes in areas that
lack brood habitat). Programs intended
to manipulate fish and wildlife popula-
tions or habitats should be undertaken
in consultation with the responsible
state or federal resource agencies.
Restoration of a functional stream corri-
dor can be expected to attract beaver in
many areas. Where beaver control is
warranted because of possible damage
to private timberlands or roads, in-
creased mosquito problems, and other
concerns, controls should be placed as
soon as possible and not after the dam-
age is done. Techniques are available to
prevent beaver from blocking culverts
or drain pipes and destroying trees. In
some cases, effective beaver control re-
quires removal of problem animals
(Olson and Hubert 1994).
Human Use
Stream corridors in urban areas are usu-
ally used heavily by people and require
much attention to minimize, control, or
repair human impacts. In some cases,
human disturbance prevents some
stream corridor functions from being
restored. For example, depending on
the amount of degradation that has oc-
curred, urban streams might support
relatively few, if any, native wildlife
species. Other concerns, such as im-
proved water quality, might be ad-
dressed effectively through proper
restoration efforts. Addressing impacts
from surrounding developed areas
(such as uncontrolled storm water
runoff and predation by pets) requires
coordination with community agencies
and citizen groups to minimize, pre-
vent, or reverse damage. Management
of urban corridors might tend to em-
9-46
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
Y A Creek Ran Through It
Portland, Oregon, sprang up along the Willa-
mette River. As time went on and the city
grew, it came to occupy a sequestered spot
between the Willamette and Columbia Rivers and
the higher reaches of the Sylvan Hills. But before
the city expanded to this point, a creek ran
through itTanner Creek.
The Tanner Creek watershed, comprising approxi-
mately 1,600 acres, extended from the forested
hills through a canyon and across the valley floor
to the Willamette River. During summer months,
the creek was placid if not dry. But during the
heavy winter rains, the creek became a raging
torrent.
As the city of Portland expanded, the creek
was diverted into the sewer system and the creek
floodway was filled in to make way for develop-
ment. These combined sewers drained directly to
the Willamette River and the Columbia Slough
until a series of interceptor pipes and a municipal
sewage treatment plant were constructed in the
1940s and 1950s.
However, this new system did not have sufficient
capacity to handle the combined sewage and
storm water flows during periods of heavy rain,
which frequently occur during the winter months.
As a result, rather than flowing to the treatment
plant for processing and disinfection, the com-
bined sewage and storm water overflowed to
outfalls along the Willamette River and the
Columbia Slough. Tanner Creek became a part of
the cause of combined sewer overflows (CSOs).
In the early 1990s, the city of Portland began to
develop a plan to eliminate CSOs. The Tanner
Creek Stream Diversion Project was identified
early in the CSO planning process as a corner-
stone project, a relatively inexpensive method
of removing clean storm water from the com-
bined system, thereby reducing CSOs. Nearly
10 miles of pipe ranging from 84 inches to 60
inches in diameter will be constructed to once
again carry storm water directly to the river. In
addition, best management practices for storm
water management will be included. Finally,
opportunities for water feature enhancements
and educational and cultural opportunities will be
explored in partnership with the community and
other agencies.
Principal among these opportunities is daylighting
a portion of the stream in the city's River District.
In partnership with community leaders, special
interest groups, a private developer, and other
agencies, the city's Bureau of Environmental
Services is leading a study of possible design
alternatives. For more information contact: Nea
Lynn Robinson, Project Manager, Tanner Creek
Stream Diversion Project, City of Portland,
Oregon.
Restoration Management
9-47
-------
Figure 9.31: Local fisherman. Fishing and other
recreational activities must be considered in
restoration management.
Figure 9.32: Off-road
vehicle. Low- and
high-impact use areas
should be clearly
marked within public
stream corridors.
phasize recreation, educational oppor-
tunities, and community activities more
than ecosystem functions. Administra-
tive concerns may focus heavily on
local ordinances, zoning, and construc-
tion permit standards and limitations.
Community involvement can be an im-
portant aspect of urban stream corridor
restoration and management. Commu-
nity groups often initiate restoration
and maintain a feeling of ownership
that translates into monitoring input,
management oversight, and volunteer
labor to conduct maintenance and
management activities. It is essential
that community groups be provided
with professional technical guidance in-
cluding assistance in translating regula-
tory requirements. It is also important
that proposed management actions in
urban corridors be discussed in advance
with interested groups affected by tree
cutting or trail closures.
In nonurban areas, recreation can usu-
ally be accommodated without impair-
ing ecological functions if all concerned
parties consider ecosystem integrity to
be the priority objective (Johnson and
Carothers 1982). Strategies can be de-
vised and techniques are available to
minimize impacts from activities such
as camping, hiking (trail erosion),
and even the use of off-road vehicles
(Cole and Marion 1988) (Figure 9.32).
Recreationists should be educated on
methods to minimize impacts on the
ecosystem and on restoration structures
and vegetation. Location of areas desig-
nated for low-impact use and areas off-
limits to certain high-impact activities
(such as off-road vehicles, biking, horse-
back riding, etc.) should be clearly
marked. Access should be restricted to
areas where new vegetation has not yet
been fully established or where vegeta-
tion could be damaged beyond the
point of survival.
9-48
Chapter 9: Restoration Implementation, Monitoring, and Management
-------
All the flowers of all the tomorrows are in the seeds of today.
-Chinese proverb
There will come a time when you believe everything is finished.
That will be the beginning.
Louis L'Amour
Restoration Management
9-49
-------
-------
Appendixes
,
-------
-------
Appendix A
"The outstanding scientific discovery of the twentieth
century is not television, or radio, but rather the complex-
ity of the land organism. Only those who know the most
about it can appreciate how little we know about it. The
last word in ignorance is the man who says of an animal
or plant: "What good is it?" If the land mechanism as a
whole is good, then every part is good, whether we
understand it nor not. If the biota, in the course of aeons,
has built something we like but do not understand, then
who but a fool would discard seemingly useless parts?
To keep every cog and wheel is the first precaution of
intelligent tinkering."
Aldo Leopold 1953, pp. 145-146
The user of
this document
is cautioned not to
attempt to replicate
or apply any of
the techniques dis-
played without
determining their
appropriateness as
an integral part of
the restoration
plan.
Introduction
The following are presented as examples of the many
techniques that are being used in support of stream
corridor restoration. Only a limited number of techniques
by broad category are shown as examples. Neither the
number of examples nor their descriptions are intended to
be exhaustive. The examples are conceptual and contain lit-
tle design guidance. All restoration techniques, however,
should be designed; often through an interdisciplinary
approach discussed in Part II of this document. Limited
guidance is provided on applications, but local standards,
criteria, and specifications should always be used.
These and other techniques have specific ranges of
applicability in terms of physical and climate adaptation,
as well as for different physiographic regions of the
country. Techniques that are selected must be components
of a system designed to restore specific functions and
values to the stream corridor. The use of any single tech-
nique, without consideration of system functions and
values, may become a short-lived, ineffective fix laid on a
system-wide problem. All restoration techniques are most
effective when included as an integral part of a restoration
plan. Typically a combination of techniques are prescribed
to address prevailing conditions and desired goals.
Effective restoration will respond to goals and objectives
that are determined locally through the planning process
described in Chapters 4 though 6.
Appendix A
A-1
-------
The restoration plan may prescribe a variety of approaches
depending on the condition of the stream corridor and the
restoration goals:
No action. Simply remove disturbance factors and "let
nature heal itself."
Management. Modify disturbance factors to allow
continued use of the corridor, while the system recovers.
Manipulation. Change watershed, corridor, or stream
conditions through land use changes, intervention, and
designed systems ranging from installing practices to
altering flow conditions, to changing stream morpholo-
gy and alignment.
Regardless of the techniques applied, they should restore
the desired functions and achieve the goals of the restora-
tion plan. The following are general considerations that
apply to many or all of the techniques in this appendix:
The potential adverse impacts from failure of these and
other techniques should be assessed before they are
used.
Techniques that change the channel slope or cross
section have a high potential for causing channel insta-
bility upstream and downstream. They should therefore
be analyzed and designed by an interdisciplinary team
of professionals. These techniques include: weirs, sills,
grade control measures, channel realignment, and
meander reconstruction.
The potential impact on flood elevations should be
analyzed before these and other techniques are used.
Many techniques will not endure on streams subject to
headcuts or general bed degradation.
Some form of toe protection will be required for many
bank treatment techniques to endure where scour of the
streambank toe is anticipated.
Any restoration technique installed in or in contact with
streams, wetlands, floodplains, or other water bodies are
subject to various federal, state, and local regulatory
programs and requirements. Most techniques presented
in this appendix would require the issuance of permits
by federal, state, and local agencies prior to installation.
A-2 Stream Corridor
-------
Appendix A: Contents
INSTREAM PRACTICES
Boulder Clusters A- 5
Weirs or Sills A - 5
Fish Passages A - 6
Log/Brush/Rock Shelters A - 6
Lunker Structures A - 7
Migration Barriers A - 7
Tree Cover A - 8
Wing Deflectors A - 8
Grade Control Measures A - 9
STREAMBANK TREATMENT
Bank Shaping and Planting A- 10
Branch Packing A- 10
Brush Mattresses A- 11
Coconut Fiber Roll A- 11
Dormant Post Plantings A- 12
Vegetated Gabions A- 12
Joint Plantings A- 13
Live Cribwalls A- 13
Live Stakes A - 14
Live Fascines A - 14
Log, Rootwad, and Boulder Revetments A- 15
Riprap A - 15
Stone Toe Protection A - 16
Tree Revetments A- 16
Vegetated Geogrids A - 17
WATER MANAGEMENT
Sediment Basins A - 18
Water Level Control A- 18
CHANNEL RECONSTRUCTION
Maintenance of Hydraulic Connections A - 19
Stream Meander Restoration A- 19
STREAM CORRIDOR MEASURES
Livestock Exclusion or Management A-20
Riparian Forest Buffers A-20
Flushing for Habitat Restoration A - 21
Appendix A A-3
-------
WATERSHED MANAGEMENT PRACTICES
Best Management Practices: Agriculture A - 22
Best Management Practices: Forestland A - 22
Best Management Practices: Urban Areas A - 23
Flow Regime Enhancement A - 23
Streamflow Temperature Management A - 24
A-4 Stream Corridor
-------
Appendix A: Techniques
INSTREAM PRACTICES
Boulder Clusters
Groups of boulders placed in the base
flow channel to provide cover, create
scour holes, or areas of reduced velocity.
Applications and Effectiveness
Can be used in most stream habitat types including riffles, runs, flats,
glides and open pools.
Greatest benefits are realized in streams with average flows exceeding 2
feet per second.
Group placements are most desirable. Individual boulder placement
might be effective in very small streams.
Most effective in wide, shallow streams with gravel or rubble beds.
Also useful in deeper streams for providing cover and improving sub-
strate.
Not recommended for sand bed (and smaller bed materials) streams
because they tend to get buried.
Added erosive forces might cause channel and bank failures.
Not recommended for streams which are aggrading or degrading.
May promote bar formation in streams with high bed material load.
For More Information
Consult the following references: Nos. 11, 13, 21, 34, 39, 55, 60, 65, 69.
Weirs or Sills
Log, boulder, or quarrystone structures
placed across the channel and anchored
to the streambank and/or bed to create
pool habitat, control bed erosion, or
collect and retain gravel.
Applications and Effectiveness
Create structural and hydraulic diversity in uniform channels.
If placed in series, they should not be so close together that all riffle and
run habitat is eliminated.
Pools will rapidly fill with sediment in streams transporting heavy bed
material loads.
Riffles often are created in downstream deposition areas.
Weirs placed in sand bed streams are subject to failure by undermining.
Potential to become low flow migration barriers.
Selection of material is important.
- Boulder weirs are generally more permeable than other materials and
might not perform well for funneling low flows. Voids between
boulders may be chinked with smaller rock and cobbles to maintain
flow over the crest.
- Large, angular boulders are most desirable to prevent movement
during high flows.
- Log weirs will eventually decompose.
Design cross channel shape to meet specific need(s).
- Weirs placed perpendicular to flow work well for creating backwater.
- Diagonal orientations tend to redistribute scour and deposition
patterns immediately downstream.
- Downstream "V's" and "U's" can serve specific functions but caution
should be exercised to prevent failures.
- Upstream "V's" or "U's" provide mid-channel, scour pools below the
weir for fish habitat, resting, and acceleration maneuvers during fish
passage.
- Center at lower elevation than sides will maintain a concentrated low
flow channel.
For More Information
Consult the following references: Nos. 11, 13, 44, 55, 58, 60, 69.
Appendix A
A-5
-------
INSTREAM PRACTICES
Fish Passages
Any one of a number of instream
changes which enhance the
opportunity for target fish species to
freely move to upstream areas for
spawning, habitat utilization, and
other life functions.
Applications and Effectiveness
Can be appropriate in streams where natural or human placed obstruc-
tions such as waterfalls, chutes, logs, debris accumulations, beaver dams,
dams, sills, and culverts interfere with fish migration.
The aquatic ecosystem must be carefully evaluated to assure that fish
passages do not adversely impact other aquatic biota and stream corridor
functions.
Slopes, depths and relative positions of the flow profile for various flow
ranges are important considerations. Salmonids, for example, can easily
negotiate through vertical water drops where the approach pool depth is
1.25 times the height of the (drop subject to an overall species-specific
limit on height) (CA Dept. of Fish and Game, 1994).
The consequences of obstruction removal for fish passage must be
carefully evaluated. In some streams, obstructions act as barriers to
undesirable exotics (e.g. sea lamprey) and are useful for scouring and
sorting of materials, create important backwater habitat, enhance organic
material input, serve as refuge for assorted species, help regulate water
temperature, oxygenate water, and provide cultural resources.
Designs vary from simple to complex depending on the site and the
target species.
For More Information
Consult the following references: Nos., 11, 69, 81.
Log/Brush/Rock Shelters
Logs, brush, and rock structures
installed in the lower portion of
streambanks to enhance fish habitat,
encourage food web dynamics, prevent
streambank erosion, and provide
shading.
Applications and Effectiveness
Most effective in low gradient stream bends and meanders where open
pools are already present and overhead cover is needed.
Create an environment for insects and other organisms to provide an
additional food source.
Can be constructed from readily available materials found near the site.
Not appropriate for unstable streams which are experiencing severe bank
erosion and/or bed degradation unless integrated with other stabilization
measures.
Important in streams where aquatic habitat deficiencies exist.
Should, where appropriate, be used with soil bioengineering systems and
vegetative plantings to stabilize the upper bank and ensure a regenerative
source of streambank vegetation.
Not generally as effective on the inside of bendways.
For More Information
Consult the following references: Nos. 11, 13, 39, 55, 65.
A-6
Stream Corridor
-------
INSTREAM PRACTICES
Lunker Structures
Cells constructed of heavy wooden planks
and blocks which are imbedded into the
toe of streambanks at channel bed level
to provide covered compartments for fish
shelter, habitat, and prevention of
streambank erosion.
Applications and Effectiveness
Appropriate along outside bends of streams where water depths can be
maintained at or above the top of the structure.
Suited to streams where fish habitat deficiencies exist.
Should, where appropriate, be used with soil bioengineering systems and
vegetative plantings to stabilize the upper bank and ensure a regenerative
source of streambank vegetation.
Are often used in conjunction with wing deflectors and weirs to direct and
manipulate flows.
Are not recommended for streams with heavy bed material loads.
Most commonly used in streams with gravel-cobble beds.
Heavy equipment may be necessary for excavating and installing the
materials.
Can be expensive.
For More Information
Consult the following references: Nos. 10, 60, 65, 85.
Migration Barriers
Obstacles placed at strategic locations
along streams to prevent undesirable
species from accessing upstream areas.
Applications and Effectiveness
Effective for specific fishery management needs such as separating species
or controlling nuisance species by creating a barrier to migration.
Must be carefully evaluated to assure migration barriers do not adversely
impact other aquatic biota and stream corridor functions.
Both physical structures or electronic measures can be used as barriers.
- Structures can be installed across most streams, but in general they are
most practical in streams with baseflows depths under two feet and
widths under thirty feet.
- Temporary measures such as seines can also be used under the above
conditions.
- Electronic barriers can be installed in deeper channels to discourage
passage. Electronic barrier employs lights, electrical pulses or sound
frequencies to discourage fish from entering the area. This technique
has the advantage of not disturbing the stream and providing a
solution for control in deep water.
Barriers should be designed so that flood flows will not flank them and
cause failures.
For More Information
Consult the following references: Nos. 11, 55.
Appendix A
A-7
-------
INSTREAM PRACTICES
Tree Cover
Felled trees placed along the
streambank to provide overhead cover,
aquatic organism substrate and
habitat, stream current deflection,
scouring, deposition, and drift
catchment.
Applications and Effectiveness
Can provide benefits at a low installation cost.
Particularly advantageous in streams where the bed is unstable and felled
trees can be secured from the top of bank.
Channels must be large enough to accommodate trees without threaten-
ing bank erosion and limiting needed channel flow capacity.
Design of adequate anchoring systems is necessary.
Not recommended if debris jams on downstream bridges might cause
subsequent problems.
Require frequent maintenance.
Susceptible to ice damage.
For More Information
Consult the following references: Nos. 11, 55, 69.
Wing Deflectors
Structures that protrude from either
streambank but do not extend entirely
across a channel. They deflect flows
away from the bank, and scour pools
by constricting the channel and
accelerating flow.
Applications and Effectiveness
Should be designed and located far enough downstream from riffle areas
to avoid backwater effects that would drown out or otherwise damage the
riffle.
Should be sized based on anticipated scour.
The material washed out of scour holes is usually deposited a short
distance downstream to form a bar or riffle
area. These areas of deposition are often composed of clean gravels that
provide excellent habitat for certain species.
Can be installed in series on alternative streambanks to produce a
meandering thalweg and associated structural diversity.
Rock and rock-filled log crib deflector structures are most common.
Should be used in channels with low physical habitat diversity, particu-
larly those with a lack of stable pool habitat.
Deflectors placed in sand bed streams may settle or fail due to erosion of
sand, and in these areas a filter layer or geotextile might be needed
underneath the deflector.
For More Information
Consult the following references: Nos. 10, 11, 18, 21, 34, 48, 55, 59, 65,
69, 77.
A-8
Stream Corridor
-------
INSTREAM PRACTICES
Grade Control Measures
Rock, wood, earth, and other material
structures placed across the channel and
anchored in the streambanks to provide a
"hard point" in the streambed that resists
the erosion forces of the degradational
zone, and/or to reduce the upstream
energy slope to prevent bed scour.
Applications and Effectiveness
If a stable channel bed is essential to the design, grade control should be
considered as a first step before any restoration measures are imple-
mented (if degradational processes exist in channel system).
Used to stop headcutting in degrading channels.
Used to build bed of incised stream to higher elevation.
Can improve bank stability in an incised channel by reducing bank
heights.
Man-made scour holes downstream of structures can provide improved
aquatic habitat.
Upstream pool areas created by structures provide increased low water
depths for aquatic habitat.
Potential to become low flow migration barrier.
Can be designed to allow fish passage.
If significant filling occurs upstream of structure, then downstream
channel degradation may result.
Upstream sediment deposition may cause increased meandering
tendencies.
Siting of structures is critical component of design process, including soil
mechanics and geotechnical engineering.
Design of grade control structures should be accomplished by an experi-
enced river engineer.
For More Information
Consult the following references: Nos. 1, 4, 5, 6, 7, 12, 17, 18, 25, 26, 31,
37, 40, 63, 66, 84.
Appendix A
A-9
-------
STREAMBANK TREATMENT
Bank Shaping and Planting
Regrading streambanks to a stable slope,
placing topsoil and other materials
needed for sustaining plant growth, and
selecting, installing and establishing
appropriate plant species.
Applications and Effectiveness
Most successful on streambanks where moderate erosion and channel
migration are anticipated.
Reinforcement at the toe of the embankment is often needed.
Enhances conditions for colonization of native species.
Used in conjunction with other protective practices where flow velocities
exceed the tolerance range for available plants, and where erosion occurs
below base flows.
Streambank soil materials, probable groundwater fluctuation, and bank
loading conditions are factors for determining appropriate slope condi-
tions.
Slope stability analyses are recommended.
For More Information
Consult the following references: Nos. 11, 14, 56, 61, 65, 67, 68, 77, 79.
Branch Packing
Alternate layers of live branches and
compacted backfill which stabilize and
revegetate slumps and holes in
streambanks.
Applications and Effectiveness
Commonly used where patches of Streambank have been scoured out or
have slumped leaving a void.
Appropriate after stresses causing the slump have been removed.
Less commonly used on eroded slopes where excavation is required to
install the branches.
Produces a filter barrier that prevents erosion and scouring from
Streambank or overbank flows.
Rapidly establishes a vegetated Streambank.
Enhances conditions for colonization of native species.
Provides immediate soil reinforcement.
Live branches serve as tensile inclusions for reinforcement once installed.
Typically not effective in slump areas greater than four feet deep or four
feet wide.
For More Information
Consult the following references: Nos. 14, 21, 34, 79, 81.
A-10
Stream Corridor
-------
STREAMBANK TREATMENT
Brush Mattresses
Combination of live stakes, live
facines, and branch cuttings installed
to cover and physically protect
streambanks; eventually to sprout and
establish numerous individual plants.
Applications and Effectiveness
Form an immediate protective cover over the streambank.
Capture sediment during flood flows.
Provide opportunities for rooting of the cuttings over the streambank.
Rapidly restores riparian vegetation and streamside habitat.
Enhance conditions for colonization of native vegetation.
Limited to the slope above base flow levels.
Toe protection is required where toe scour is anticipated.
Appropriate where exposed streambanks are threatened by high flows
prior to vegetation establishment.
Should not be used on slopes which are experiencing mass movement or
other slope instability.
For More Information
Consult the following references: Nos. 14, 21, 34, 56, 65, 77, 79, 81.
Coconut Fiber Roll
Cylindrical structures composed of
coconut husk fibers bound together
with twine woven from coconut
material to protect slopes from erosion
while trapping sediment which
encourages plant growth within the
fiber roll.
Applications and Effectiveness
Most commonly available in 12 inch diameter by 20 foot lengths.
Typically staked near the toe of the streambank with dormant cuttings
and rooted plants inserted into slits cut into the rolls.
Appropriate where moderate toe stabilization is required in conjunction
with restoration of the streambank and the sensitivity of the site allows
for only minor disturbance.
Provide an excellent medium for promoting plant growth at the water's
edge.
Not appropriate for sites with high velocity flows or large ice build up.
Flexibility for molding to the existing curvature of the streambank.
Requires little site disturbance.
The rolls are buoyant and require secure anchoring.
Can be expensive.
An effective life of 6 to 10 years.
Should, where appropriate, be used with soil bioengineering systems and
vegetative plantings to stabilize the upper bank and ensure a regenerative
source of streamside vegetation.
Enhances conditions for colonization of native vegetation.
For More Information
Consult the following references: Nos. 65, 77.
Appendix A
A-11
-------
STREAMBANK TREATMENT
Dormant Post Plantings
Plantings of cottonwood, willow, poplar,
or other species embedded vertically into
streambanks to increase channel
roughness, reduce flow velocities near the
slope face, and trap sediment.
Applications and Effectiveness
Can be used as live piling to stabilize rotational failures on streambanks
where minor bank sloughing is occurring.
Useful for quickly establishing riparian vegetation, especially in arid
regions where water tables are deep.
Will reduce near bank stream velocities and cause sediment deposition in
treated areas.
Reduce streambank erosion by decreasing the near-bank flow velocities.
Generally self-repairing and will restem if attacked by beaver or livestock;
however, provisions should be made to exclude such herbivores where
possible.
Best suited to non-gravely streams where ice damage is not a problem.
Will enhance conditions for colonization of native species.
Are less likely to be removed by erosion than live stakes or smaller
cuttings.
Should, where appropriate, be used with soil bioengineering systems and
vegetative plantings to stabilize the upper bank and ensure a regenerative
source of streamside vegetation.
Unlike smaller cuttings, post harvesting can be very destructive to the
donor stand, therefore, they should be gathered as 'salvage' from sites
designated for clearing, or thinned from dense stands.
For More Information
Consult the following references: Nos. 65, 77, 79.
Vegetated Gabions
Wire-mesh, rectangular baskets filled with
small to medium size rock and soil and
laced together to form a structural toe or
sidewalk Live branch cuttings are placed
on each consecutive layer between the
rock filled baskets to take root,
consolidate the structure, and bind it to
the slope.
Applications and Effectiveness
Useful for protecting steep slopes where scouring or undercutting is
occurring or there are heavy loading conditions.
Can be a cost effective solution where some form of structural solution is
needed and other materials are not readily available or must be brought
in from distant sources.
Useful when design requires rock size greater than what is locally available.
Effective where bank slope is steep and requires moderate structural support.
Appropriate at the base of a slope where a low toe wall is needed to
stabilize the slope and reduce slope steepness.
Will not resist large, lateral earth stresses.
Should, where appropriate, be used with soil bioengineering systems and
vegetative plantings to stabilize the upper bank and ensure a regenerative
source of streambank vegetation.
Require a stable foundation.
Are expensive to install and replace.
Appropriate where channel side slopes must be steeper than appropriate
for riprap or other material, or where channel toe protection is needed,
but rock riprap of the desired size is not readily available.
Are available in vinyl coated wire as well as galvanized steel to improve
durability.
Not appropriate in heavy bedload streams or those with severe ice action
because of serious abrasion damage potential.
For More Information
Consult the following references: Nos. 11, 18, 34, 56, 77.
A-12
Stream Corridor
-------
STREAMBANK TREATMENT
Joint Plantings
Live stakes tamped into joints or openings
between rock which have previously been
installed on a slope or while rock is being
placed on the slope face.
Applications and Effectiveness
Appropriate where there is a lack of desired vegetative cover on the face
of existing or required rock riprap.
Root systems provide a mat upon which the rock riprap rests and prevents
loss of fines from the underlying soil base.
Root systems also improve drainage in the soil base.
Will quickly establish riparian vegetation.
Should, where appropriate, be used with other soil bioengineering
systems and vegetative plantings to stabilize the upper bank and ensure a
regenerative source of streambank vegetation.
Have few limitations and can be installed from base flow levels to top of
slope, if live stakes are installed to reach ground water.
Survival rates can be low due to damage to the cambium or lack of soil/
stake interface.
Thick rock riprap layers may require special tools for establishing pilot
holes.
For More Information
Consult the following references: Nos. 21, 34, 65, 77, 81.
Live Cribwalls
Hollow, box-like interlocking
arrangements of untreated log or timber
members filled above baseflow with
alternate layers of soil material and live
branch cuttings that root and gradually
take over the structural functions of the
wood members.
Applications and Effectiveness
Provide protection to the streambank in areas with near vertical banks
where bank sloping options are limited.
Afford a natural appearance, immediate protection and accelerate the
establishment of woody species.
Effective on outside of bends of streams where high velocities are present.
Appropriate at the base of a slope where a low wall might be required to
stabilize the toe and reduce slope steepness.
Appropriate above and below water level where stable streambeds exist.
Don't adjust to toe scour.
Can be complex and expensive.
Should, where appropriate, be used with soil bioengineering systems and
vegetative plantings to stabilize the upper bank and ensure a regenerative
source of streambank vegetation.
For More Information
Consult the following references: Nos. 11, 14, 21, 34, 56, 65, 77, 81.
Appendix A
A-13
-------
STREAMBANK TREATMENT
Live Stakes
Live, woody cuttings which are tamped
into the soil to root, grow and create a
living root mat that stabilizes the soil by
reinforcing and binding soil particles
together, and by extracting excess soil
moisture.
Applications and Effectiveness
Effective where site conditions are uncomplicated, construction time is
limited, and an inexpensive method is needed.
Appropriate for repair of small earth slips and slumps that are frequently
wet.
Can be used to stake down surface erosion control materials.
Stabilize intervening areas between other soil bioengineering techniques.
Rapidly restores riparian vegetation and streamside habitat.
Should, where appropriate, be used with other soil bioengineering
systems and vegetative plantings.
Enhance conditions for colonization of vegetation from the surrounding
plant community.
Requires toe protection where toe scour is anticipated.
For More Information
Consult the following references: Nos. 14, 21, 34, 56, 65, 67, 77, 79, 81.
Live Fascines
Dormant branch cuttings bound together
into long sausage-like, cylindrical bundles
and placed in shallow trenches on slopes
to reduce erosion and shallow sliding.
Applications and Effectiveness
Can trap and hold soil on streambank by creating small dam-like
structures and reducing the slope length into a series of shorter slopes.
Facilitate drainage when installed at an angle on the slope.
Enhance conditions for colonization of native vegetation.
Should, where appropriate, be used with other soil bioengineering
systems and vegetative plantings.
Requires toe protection where toe scour is anticipated.
Effective stabilization technique for streambanks, requiring a minimum
amount of site disturbance.
Not appropriate for treatment of slopes undergoing mass movement.
For More Information
Consult the following references: Nos. 14, 21, 34, 65, 77, 81.
A-14
Stream Corridor
-------
STREAMBANK TREATMENT
Log, Rootwad, and
Boulder Revetments
Boulders and logs with root masses
attached placed in and on streambanks to
provide streambank erosion, trap
sediment, and improve habitat diversity.
Applications and Effectiveness
Will tolerate high boundary shear stress if logs and rootwads are well
anchored.
Suited to streams where fish habitat deficiencies exist.
Should, where appropriate, be used with soil bioengineering systems and
vegetative plantings to stabilize the upper bank and ensure a regenerative
source of streambank vegetation.
Will enhance diversity in riparian areas when used with soil bioengineer-
ing systems.
Will have limited life depending on climate and tree species used. Some
species, such as cottonwood or willow, often sprout and accelerate
colonization.
Might need eventual replacement if colonization does not take place or
soil bioengineering systems are not used.
Use of native materials can sequester sediment and woody debris, restore
streambanks in high velocity streams, and improve fish rearing and
spawning habitat.
Site must be accessible to heavy equipment.
Materials might not be readily available at some locations.
Can create local scour and erosion.
Can be expensive.
For More Information
Consult the following references: Nos. 11, 34, 77.
Riprap
A blanket of appropriately sized stones
extending from the toe of slope to a
height needed for long term durability.
Applications and Effectiveness
Can be vegetated (see joint plantings).
Appropriate where long term durability is needed, design discharge are
high, there is a significant threat to life or high value property, or there is
no practical way to otherwise incorporate vegetation into the design.
Should, where appropriate, be used with soil bioengineering systems and
vegetative plantings to stabilize the upper bank and ensure a regenerative
source of streambank vegetation.
Flexible and not impaired by slight movement from settlement or other
adjustments.
Should not be placed to an elevation above which vegetative or soil
bioengineering systems are an appropriate alternative.
Commonly used form of bank protection.
Can be expensive if materials are not locally available.
For More Information
Consult the following references: Nos. 11, 14, 18, 34, 39, 56, 67, 70, 77.
Appendix A
A-15
-------
STREAMBANK TREATMENT
Stone Toe Protection
A ridge of quarried rock or stream cobble
placed at the toe of the streambank as an
armor to deflect flow from the bank,
stabilize the slope and promote sediment
deposition.
Applications and Effectiveness
Should be used on streams where banks are being undermined by toe
scour, and where vegetation cannot be used.
Stone prevents removal of the failed streambank material that collects at
the toe, allows revegetation and stabilizes the streambank.
Should, where appropriate, be used with soil bioengineering systems and
vegetative plantings to stabilize the upper bank and ensure a regenerated
source of streamside vegetation.
Can be placed with minimal disturbance to existing slope, habitat, and
vegetation.
For More Information
Consult the following references: Nos. 10, 21, 56, 67, 77, 81.
Tree Revetments
A row of interconnected trees attached to
the toe of the streambank or to deadmen
in the streambank to reduce flow
velocities along eroding streambanks, trap
sediment, and provide a substrate for
plant establishment and erosion control.
Applications and Effectiveness
Design of adequate anchoring systems is necessary.
Wire anchoring systems can present safety hazards.
Work best on streams with streambank heights under 12 feet and bankfull
velocities under 6 feet per second.
Use inexpensive, readily available materials.
Capture sediment and enhances conditions for colonization of native
species particularly on streams with high bed material loads.
Limited life and must be replaced periodically.
Might be severely damaged by ice flows.
Not appropriate for installation directly upstream of bridges and other
channel constrictions because of the potential for downstream damages
should the revetment dislodge.
Should not be used if they occupy more than 15 percent of the channel's
cross sectional area at bankfull level.
Not recommended if debris jams on downstream bridges might cause
subsequent problems.
Species that are resistant to decay are best because they extend the
establishment period for planted or volunteer species that succeed them.
Requires toe protection where toe scour is anticipated.
Should, where appropriate, be used with soil bioengineering systems and
vegetative plantings to stabilize the upper bank and ensure a regenerated
source of streamside vegetation.
For More Information
Consult the following references: Nos. 11, 21, 34, 56, 60, 77, 79.
A-16
Stream Corridor
-------
STREAMBANK TREATMENT
Vegetated Geogrids
Alternating layers of live branch cuttings
and compacted soil with natural or
synthetic geotextile materials wrapped
around each soil lift to rebuild and
vegetate eroded streambanks.
Applications and Effectiveness
Quickly establish riparian vegetation if properly designed and installed.
Can be installed on a steeper and higher slope and has a higher initial
tolerance of flow velocity than brush layering.
Can be complex and expensive.
Produce a newly constructed, well-reinforced streambank.
Useful in restoring outside bends where erosion is a problem.
Capture sediment and enhances conditions for colonization of native
species.
Slope stability analyses are recommended.
Can be expensive.
Require a stable foundation.
For More Information
Consult the following references: Nos. 10, 11, 14, 21, 34, 56, 65, 77.
Appendix A
A-17
-------
WATER MANAGEMENT
Sediment Basins
Barriers, often employed in conjunction
with excavated pools, constructed across a
drainage way or off-stream and connected
to the stream by a flow diversion channel
to trap and store waterborne sediment
and debris.
Applications and Effectiveness
Provide an interim means of reducing the sediment load from a stream.
Used occasionally to sort sediment sizes.
Temporarily reduce excessive sediment loads until the upstream water-
shed can be protected from accelerated erosion.
Can also be used to separate out sediment which may be causing dam-
ages downstream along reaches which are incapable of transporting the
sediment sizes.
Can be integrated with more permanent stormwater management ponds.
Can only trap the upper range of particle sizes (sand and gravel) and
allow finer particles (silt and clay) to pass through.
Require a high level of analysis.
Require periodic dredging and other maintenance.
For More Information
Consult the following references: Nos. 10, 13, 29, 45, 49, 69, 74, 80.
Water Level Control
Managing water levels within the
channel and adjoining riparian zone to
control aquatic plants and restore
desired functions, including aquatic
habitat.
Applications and Effectiveness
Appropriate where flow depth in the stream, adjoining wetland, or the
interdependent saturation zone in the adjoining riparian area is insuffi-
cient to provide desired functions.
Need will often vary by season and requires flexible control devices
which can be managed accordingly.
The complexities of maintaining sediment balances, temperature eleva-
tion, change in channel substrate, changes in flow regime, and a host of
other considerations must be factored into planning and design.
Requires a high level of analysis.
For More Information
Consult the following references: Nos. 11, 13, 15, 69, 75.
A-18
Stream Corridor
-------
CHANNEL RECONSTRUCTION
Maintenance of
Hydraulic Connections
Maintenance of hydraulic connectivity to
allow movement of water and biota
between the stream and abandoned
channel reaches.
Applications and Effectiveness
Used to prevent losses of aquatic habitat area and diversity.
Slackwater areas adjoining the main channel have potential for spawning
and rearing areas for many fish species and are a key component of
habitat for wildlife species that live in or migrate through the riparian
corridor.
Recreation value can be enhanced if connecting channels are deep enough
for small boats or canoes.
Effective along reaches of realigned channel where cutoffs have been
made.
Not effective in streams with insufficient stages or discharges to maintain
satisfactory hydraulic connections to the abandoned channel reaches.
May require maintenance if sedimentation is a problem.
May have limited life.
Require a high level of analysis.
For More Information
Consult the following references: Nos. 15, 56, 69, 75.
Stream Meander
Restoration
Transformation of a straightened stream
into a meandering one to reintroduce
natural dynamics improve channel
stability, habitat quality, aesthetics, and
other stream corridor functions or values.
Applications and Effectiveness
Used to create a more stable stream with more habitat diversity.
Requires adequate area where adjacent land uses may constrain locations.
May not be feasible in watersheds experiencing rapid changes in land
uses.
Streambank protection might be required on the outside of bends.
Significant risk of failure.
Requires a high level of analysis.
May cause significant increases in flood elevations.
Effective discharge should be computed for both existing and future
conditions, particularly in urbanized watersheds.
For More Information
Consult the following references: Nos. 13, 16, 22, 23, 24, 46, 47, 52, 53,
54, 56, 61, 72, 75, 77, 78, 79, 86.
Appendix A
A-19
-------
STREAM CORRIDOR MEASURES
Livestock Exclusion
or Management
Applications and Effectiveness
Appropriate where livestock grazing is negatively impacting the stream
corridor by reducing growth of woody vegetation, decreasing water
quality, or contributing to the instability of streambanks.
Once the system has recovered, rotational grazing may be incorporated
into the management plan.
Must be coordinated with an overall grazing plan.
For More Information
Consult the following references: Nos. 18, 39, 73.
Fencing, alternate sources of water and
shelter, and managed grazing to protect,
maintain, or improve riparian flora and
fauna and water quality.
Riparian Forest Buffers
Streamside vegetation to lower water
temperatures, provide a source of detritus
and large woody debris, improve habitat,
and to reduce sediment, organic material,
nutrients, pesticides and other pollutants
migrating to the stream.
Applications and Effectiveness
Applicable on stable areas adjacent to permanent or intermittent streams,
lakes, ponds, wetlands and areas with ground water recharge.
Unstable areas such as those with high surface erosion rates, mass soil
movement, or active gullies will require stabilization prior to establish-
ment of riparian forest buffers.
Tolerant plant species and supplemental watering may be needed in
some areas.
Sites in arid and semi-arid regions may not have sufficient soil moisture
throughout the growing season to support woody plants.
Concentrated flow erosion, excessive sheet and rill erosion, or mass soil
movement must be controlled in upland areas prior to establishment of
riparian forest buffers.
For More Information
Consult the following references: Nos. 20, 34, 49, 51, 70, 78, 79, 81, 82,
88, 89.
A-20
Stream Corridor
-------
STREAM CORRIDOR MEASURES
Flushing for Habitat
Restoration
A high-magnitude, short duration release
from a reservoir to scour fine-grained
sediments from the streambed and restore
suitable instream habitat.
Applications and Effectiveness
Appropriate as part of an overall watershed management plan.
May cause flooding of old floodplains below dams, depletion of gravel
substrates, and significant changes in channel geometry.
Flushing of fine sediments at one location may only move the problem
further downstream.
Seasonal discharge limits, rate of change of flow, and river stages down-
stream of impoundment should be considered to avoid undesirable
impacts to instream and riparian habitat.
Can be effective in improving gradation of streambed materials, suppres-
sion of aquatic vegetation, and maintenance of stream channel geometry
necessary for desired instream habitat.
Can induce floodplain scouring to provide suitable growing conditions
for riparian vegetation.
Requires high level of analysis to determine necessary release schedule.
May not be feasible in areas where water rights are fully allocated.
For More Information
Consult the following references: Nos. 11, 13, 32, 35, 41, 45, 57, 61, 73,
74, 81.
Appendix A
A-21
-------
WATERSHED MANAGEMENT
Best Management
Practices: Agriculture
Individual and systematic approaches
aimed at mitigating non-point source
pollution from agricultural land.
Applications and Effectiveness
Used where current management systems are causing problems on-site or
within farm or field boundaries and have a high potential to impact the
stream corridor.
Also applied where watershed management plans are being implemented
to improve environmental conditions.
Must fit within a comprehensive farm management plan, a watershed
action plan, or a stream corridor restoration plan.
Should consider the four season conservation of the soil, water, and
microbial resources base.
Tillage, seeding, fertility, pest management, and harvest operations should
consider environmental qualities and the potential to use adjacent lands
in water and soil conservation and management and pest management.
Grazing land management should protect environmental attributes,
including native species protection, while achieving optimum, long-term
resource use.
Where crops are raised and the land class allows, pastures should be
managed with crop rotation sequences to provide vigorous forage cover
while building soil and protecting water and wildlife qualities.
Orchards and nursery production should actively monitor pest and water
management techniques to protect ecosystem quality and diversity.
Farm woodlots, wetlands, and field borders should be part of an overall
farm plan that conserves, protects, and enhances native plants and
animals, soil, water, and scenic qualities.
BMPs may include: contour farming, conservation tillage, terracing,
critical area planting, nutrient management, sediment basins, filter strips,
waste storage management, and integrated pest management.
For More Information
Consult the following references: Nos. 73, 78, 81.
Best Management
Practices: Forestland
Individual and systematic approaches for
mitigating non-point source pollution
from forestland.
Applications and Effectiveness
Used where current management systems are causing problems in the
watershed and have a high potential to impact the stream corridor.
Also applied where management plans are being implemented to restore
one or more natural resource functions in a watershed.
Must consider how it fits within a comprehensive forestland management
plan, a watershed action plan, or a stream corridor restoration plan.
BMPs may include: preharvest planning, streamside management
measures, road construction or reconstruction, road management, timber
harvesting, site preparation and forest generation, fire management,
revegetation of disturbed areas, forest chemical management, and forest
wetland management.
For More Information
Consult the following references: Nos. 9, 20, 27, 30, 34, 42, 49, 51, 70,
78, 79, 81, 82, 83, 88, 89.
A-22
Stream Corridor
-------
WATERSHED MANAGEMENT
Best Management
Practices: Urban Areas
Individual or systematic approaches
designed to offset, reduce, or protect
against the impacts of urban development
and urban activities on the stream
corridor.
Applications and Effectiveness
Used to improve and/or restore ecological functions which have been
impaired by urban activities.
Needs to be integrated with BMPs on other lands in the landscape to
assure that stream restoration is applied along the entire stream corridor
to the extent possible.
The use of individual urban BMPs should be coordinated with an overall
plan for restoring the stream system.
Urban sites are highly variable and have a high potential for disturbance.
Applicability of the treatment to the site situation in terms of physical
layout, relationship to the overall system, arrangements for maintenance,
and protection from disturbances are often critical considerations.
BMPs may include: extended detention dry basins, wet ponds, con-
structed wetlands, oil-water separators, vegetated swales, filter strips,
infiltration basins and trenches, porous pavement, and urban forestry.
For More Information
Consult the following references: Nos. 29, 34, 43, 49, 78, 80, 81, 83.
Flow Regime Enhancement
Manipulation of watershed features (such
as changes in land use or construction of
impoundments) for the purpose of
controlling streamflow and improving
physical, chemical and biological
functions.
Applications and Effectiveness
Appropriate where human-induced changes have altered stream flow
characteristics to the extent that streams no longer support their former
functions.
Can restore or improve threatened functions (e.g., substrate materials or
distribution of flow velocities to support the natural food web).
Can require extensive changes over broad areas involving many land
users.
Can be expensive.
Has been used for remediation of depleted dissolved oxygen levels,
reduction in salinity levels, or to maintain a minimum flow level for
downstream users.
Must determine what impacts from historical changes in the flow regime
over time can be mitigated using flow enhancement techniques.
For More Information
Consult the following references: Nos. 32, 39, 45, 57, 75, 81.
Appendix A
A-23
-------
WATERSHED MANAGEMENT
Streamflow Temperature
Management
Streamside vegetation and upland
practices to reduce elevated streamflow
temperatures.
Applications and Effectiveness
Effective for smaller streams where bank vegetation can provide substan-
tial shading of the channel and on which much of the canopy has been
removed.
Appropriate practices are those that establish Streamside vegetation,
increase vegetative cover, increase infiltration and subsurface flow,
maintain base flow, and reduce erosion.
Turbid water absorbs more solar radiation than clear; therefore, erosion
control in watersheds can help in reducing thermal pollution.
Flow releases from cooler strata of reservoirs must be exercised with
caution. Although cooler, water from this source is generally low in
dissolved oxygen and must be aerated before discharging downstream.
Selective mixing of the reservoir withdrawal can moderate temperature as
may be required.
There might be opportunities in irrigated areas to cool return flows prior
to discharge to streams.
For More Information
Consult the following references: Nos. 32, 39, 45, 73, 80, 81, 88, 89.
A-24
Stream Corridor
-------
Appendix A: List of References
1. Abt, S.R., G.B. Hamilton, C.C. Watson,
and J.B. Smith. 1994. Riprap sizing for
modified ARS-Type basin. Journal of
Hydraulic Engineering, ASCE 120(2):
260-267.
2. Biedenharn, D.S., C.M. Elliott, and C.C.
Watson. 1997. The WES stream investi-
gation and streambank stabilization
handbook. Prepared for the U.S. Environ-
mental Protection Agency by the U.S.
Army Corps of Engineers Waterways
Experiment Station Vicksburg, Mississippi.
3. Blaisdell, F.W. 1948. Development and
hydraulic design, Saint Anthony Falls
stilling basin. American Society of Civil
Engineers, Trans. 113:483-561, Paper No.
2342.
4. Clay, C.H. 1961. Design of fishways and
other fish facilities. Department of
Fisheries and Oceans, Canada, Queen's
Printer, Ottawa.
5. Cooper, C.M., and S.S. Knight. 1987.
Fisheries in man-made pools below grade
control structures and in naturally occur-
ring scour holes of unstable streams.
Journal of Soil and Water Conservation 42:
370-373.
6. Darrach, A.G. et al. 1981. Building water
pollution control into small private forest and
ranchland roads. Publication R6-S&PF-
006-1980. U.S. Department of Agricul-
ture, Forest Service, Portland, Oregon.
7. DuPoldt, C.A., Jr. 1996. Compilation of
technology transfer information from the
XXVII conference of the International Erosion
Control Association. U.S. Department of
Agriculture, Natural Resources Conserva-
tion Service, Somerset, New Jersey.
8. Flosi, G., and F. Reynolds. 1991.
California salmonid stream habitat and
restoration manual. California Department
of Fish and Game.
9. Goitom, T.G., and M.E. Zeller. 1989.
Design procedures for soil-cement grade
control structures. In Proceedings of the
National Conference of Hydraulic Engineer-
ing, American Society of Civil Engineers,
New Orleans, Louisiana.
10. Gore, J.A., and F.D. Shields. 1995. Can
large rivers be restored? A focus on
rehabilitation. Bioscience 45 (3).
11. Gray, D.H., and A.T. Leiser. 1982.
Biotechnical slope protection and erosion
control. Van Nostrand Reinholm, New
York.
12. Hammer, D.A. 1992. Creating freshwater
wetlands. Lewis Publishers, Chelsea,
Michigan.
13. Harrelson, C.C., J.P. Potyondy, C.L.
Rawlins. 1994. Stream channel reference
sites: an illustrated guide to field technique.
General Technical Report RM-245. U.S.
Department of Agriculture, Forest Service,
Fort Collins, CO.
14. Harris, EC. 1901. Effects of dams and
like obstructions in silt-bearing streams.
Engineering News 46.
15. Henderson, J.E. 1986. Environmental
designs for streambank protection
projects. Water Resources Bulletin 22(4):
549-558.
16. Iowa State University, University
Extension. 1996. Buffer strip design,
establishment and maintenance. In
Stewards of Our Streams. Ames, Iowa.
Appendix A
A-25
-------
17. King County, Washington Department of
Public Works. 1993. Guidelines for bank
stabilization projects. Seattle, Washington.
18. Leopold, A. 1949. A Sand County almanac
and sketches here and there. Oxford Univer-
sity Press, New York.
19. Leopold, L.B., and D.L. Rosgen. 1991.
Movement of bed material clasts in gravel
streams. In Proceedings of the Fifth Federal
Interagency Sedimentation Conference. Las
Vegas, Nevada.
20. Leopold, L.B., and M.G. Wolman. 1957.
River and channel patterns: braided, mean-
dering, and straight. Professional Paper
282-B. LI.S. Geological Survey,
Washington, DC.
21. Linder, W.M. 1963. Stabilization of stream
beds with sheet piling and rock sills. Pre-
pared for Federal Interagency Sedimenta-
tion Conference, Subcommittee on
Sedimentation, ICWR, Jackson,
Mississippi.
22. Little, W.C., and J.B. Murphy. 1982.
Model study of low drop grade control
structures. Journal of the Hydraulic Division,
ASCE, Vol. 108, No. HY10, October, 1982,
pp. 1132- 1146.
23. Logan, R., and B. Clinch. 1991. Montana
forestry BMP's. Montana Department of
State Lands, Service Forestry Bureau.
Missoula, Montana.
24. Maryland Department of the Environ-
ment, Water Management Administration.
1994. 1994 Maryland standards and
specifications for soil erosion and sediment
control. In association with Soil Conserva-
tion Service and Maryland State Soil
Conservation Committee, Annapolis,
Maryland.
25. Maryland Department of Natural Re-
sources, Forest Service. 1993. Soil erosion
and sediment control guidelines for forest
harvest operations in Maryland. Annapolis,
Maryland.
26. McLaughlin Water Engineers, Ltd. 1986.
Evaluation of and design recommendations for
drop structures in the Denver metropolitan
area. A Report prepared for the Denver
Urban Drainage and Flood Control
District.
27. McMahon, T.A. 1993. Hydrologic design
for water use. In Handbook of Hydrology, ed.
D.R. Maidment. McGraw-Hill, New York.
28. Metropolitan Washington Council of
Governments. 1992. Watershed restoration
source book. Department of Environmental
Programs, Anacostia Restoration Team,
Washington, DC.
29. Milhous, R.T., and R. Dodge. 1995.
Flushing flow for habitat restoration. In
Proceedings of the First International Confer-
ence on Water Resources Engineering, ed.
W.H. Espey, Jr. and P.G. Combs. American
Society of Civil Engineers, New York.
30. Minnesota Department of Natural
Resources. 1995. Protecting water quality
and wetlands in forest management. St.
Paul, Minnesota.
31. Murphy, T.E. 1967. Drop structures for
Gering Valley project, Scottsbluff County,
Nebraska, Hydraulic Model investigation.
Technical Report No. 2-760. U.S. Army
Corps of Engineers Waterways Experiment
Station, Vicksburg, Mississippi.
32. National Research Council. 1992.
Restoration of aquatic ecosystems: science,
technology and public policy. National
Academy Press, Washington, DC.
A-26
Stream Corridor
-------
33. Neilson, P.M., T.N. Waller, and K.M.
Kennedy. 1991. Annotated bibliography on
grade control structures. Miscellaneous
Paper, HL-914. U.S. Army Corps of
Engineers Waterways Experiment Station,
Vicksburg, Mississippi.
34. Nelson, W.R., J.R. Dwyer, and W.E.
Greenberg. 1988. Flushing and scouring
flows for habitat maintenance in regulated
streams. U.S. Environmental Protection
Agency, Washington, DC.
35. New Hampshire Timberland Owners
Association. 1991. A pocket field guide for
foresters, landowners and loggers. Concord,
New Hampshire.
36. New York Department of Environmental
Conservation. 1992. Reducing the impacts
of stormwater runoff from new development.
Albany, New York.
37. Pennsylvania Fish Commission.
(Undated). Fish habitat improvement for
streams. Pennsylvania Fish Commission,
Harrisburg, Pennsylvania.
38. Reid, G.K., and R. D. Wood. 1976.
Ecology of inland waters and estuaries.
D. Van Nostrand Co., New York.
39. Rosgen, D.L. 1985. A stream classification
systemriparian ecosystems and their
management. First North American
Riparian Conference, Tucson, Arizona.
40. Rosgen, D.L. 1993. River restoration
using natural stability concepts. In
Proceedings of Watershed '93, A National
Conference on Watershed Management.
Alexandria, Virginia.
41. Saele, L.M. 1994. Guidelines for the design
of stream barbs. Streambank Protection
and Restoration Conference. U.S. Depart-
ment of Agriculture, Natural Resources
Conservation Service, Portland, Oregon.
42. Schueler, T.R. 1987. Controlling urban
runoff: a practical manual for planning and
designing urban BMPs. Metropolitan
Washington Council of Governments,
Washington, DC.
43. Schultz, R.C., J.P. Colletti, T.M. Isenhart,
W.W. Simpkings, C.W. Mize, and M.L.
Thompson. 1995. Design and placement
of a multi-species riparian buffer strip.
Agroforestry Systems 29: 201-225.
44. Schumm, S.A. 1963. A tentative classifica-
tion system of alluvial rivers. Circular 477.
U.S. Geological Survey, Washington, DC.
45. Schumm, S.A. 1977. The fluvial system.
John Wiley and Sons, New York.
46. Schumm, S.A., M.D. Harvey, and C.A.
Watson. 1984. Incised channels: morpholo-
gy, dynamics and control. Water Resources
Publications, Littleton, Colorado.
47. Seehorn, M.E. 1992. Stream habitat
improvement handbook. Technical Publica-
tion R8-TP 16. U.S. Department of
Agriculture, Forest Service, Atlanta,
Georgia.
48. Shields, F.D., Jr. 1982. Environmental
features for flood control channels. Water
Resources Bulletin, AWRA 18(5): 779-784.
49. Shields, F.D., Jr. 1983. Design of habitat
structures open channels. Journal of Water
Resources Planning and Management, ASCE
109: 4.
Appendix A
A-27
-------
50. Shields, F.D., Jr., and N.M. Aziz. 1992.
Knowledge-based system for environmen-
tal design of stream modifications. Applied
Engineering in Agriculture, ASCE 8:4.
51. Shields, F.D., Jr., and R.T. Milhous. 1992.
Sediment and aquatic habitat in river
systems. Final Report. American Society
of Civil Engineers Task Committee on
Sediment Transport and Aquatic Habitat.
Journal of Hydraulic Engineering 118(5).
52. Shields, F.D., Jr., C.M. Cooper, and S.S.
Knight. 1992. Rehabilitation of aquatic
habitats in unstable streams. Fifth Sympo-
sium on River Sedimentation. Karlsruhe.
53. Shields, F.D., Jr., S.S. Knight, and C.M.
Cooper. 1995. Incised stream physical
habitat restoration with stone weirs.
Regulated Rivers: Research and Management
10.
54. Tate, C.H., Jr. 1988. Muddy Creek grade
control structures, Muddy Creek, Mississippi
and Tennessee. Technical Report HL-88-11.
U.S. Army Corps of Engineers Waterways
Experiment Station, Vicksburg,
Mississippi.
55. Thompson, J.N., and D.L. Green. 1994.
Riparian restoration and streamside erosion
control handbook. Tennessee Department
of Environment and Conservation,
Nashville, Tennessee.
56. U.S. Army Corps of Engineers. 1970.
Hydraulic Design of Flood Control Channels.
EM-1110-1601, (Revision in press 1990).
57. U.S. Army Corps of Engineers. 1981.
Main report, Final report to Congress on
die streambank erosion control evaluation
and demonstration Act of 1974, Section
32, Public Law 93-251. U.S. Army Corps
of Engineers, Washington, DC.
A-28
58. U.S. Army Corps of Engineers. 1983.
Streambank protection guidelines. U.S.
Army Corps of Engineers, Washington,
DC.
59. U.S. Army Corps of Engineers. 1989.
Engineering and design: environmental
engineering for local flood control
channels. Engineer Manual No. 1110-2-
1205. Department of the Army, U.S. Army
Corps of Engineers, Washington, DC.
60. U.S. Department of Agriculture, Forest
Service. 1989. Managing grazing of
riparian areas in the Intermountain Region,
prepared by Warren P. Clary and Bert F.
Webster. General Technical Report INT-
263. Intermountain Research Station,
Ogden, UT.
61. U.S. Department of Agriculture, Soil
Conservation Service. 1977. Design of
open channels. Technical Release 25.
62. U.S. Department of Agriculture, Natural
Resources Conservation Service. (Con-
tinuously updated). National handbook
of conservation practices. Washington,
DC.
63. U.S. Department of Agriculture, Soil
Conservation Service. (1983). Sediment-
storage design criteria. In National
Engineering Handbook, Section 3. Sedi-
mentation, Chapter 8. Washington, DC.
64. U.S. Department of Agriculture, Natural
Resources Conservation Service. 1992.
Wetland restoration, enhancement or
creation. In Engineering Field Handbook.
Chapter 13. Washington, DC.
65. U.S. Department of Agriculture, Natural
Resources Conservation Service. 1992.
Soil bioengineering for upland slope
protection and erosion reduction. In
Engineering field handbook, Part 650,
Chapter 18.
Stream Corridor
-------
66. U.S. Department of Agriculture, Natural
Resources Conservation Service. 1995.
Riparian forest buffer, 391, model state
standard and general specifications. Water-
shed Science Institute, Agroforesters
and Collaborating Partners, Seattle,
Washington.
67. U.S. Department of Agriculture, Natural
Resources Conservation Service. c!995.
(Unpublished draft). Planning and design
guidelines for streambank protection. South
National Technical Center, Fort Worth,
Texas.
68. U.S. Department of Agriculture, Natural
Resources Conservation Service. 1996.
Streambank and shoreline protection. In
Engineering field handbook, Part 650,
Chapter 16.
69. U. S. Department of Agriculture, Natural
Resources Conservation Service, and
Illinois Environmental Protection Agency.
1994. Illinois Urban Manual. Champaign,
Illinois.
70. U.S. Environmental Protection Agency.
1993. Guidance specifying management
measures for sources of nonpoint pollution in
coastal waters. Publication 840-B-92-002.
U.S. Environmental Protection Agency,
Office of Water, Washington, DC.
71. U.S. Environmental Protection Agency.
1995. Water quality of riparian forest buffer
systems in the Chesapeake Bay Watershed.
EPA-903-R-95-004. Prepared by the
Nutrient Subcommittee of the Chesapeake
Bay Program.
72. U.S. Department of Transportation.
1975. Highways in the river environment
hydraulic and environmental design consider-
ations. Training and Design Manual.
73. Vanoni, V.A., and R.E. Pollack. 1959.
Experimental design of low rectangular drops
for alluvial flood channels. Report No. E-82.
California Institute of Technology,
Pasadena, California.
74. Vitrano, D.M. 1988. Unit construction of
trout habitat improvement structures for
Wisconsin Coulee streams. Administrative
Report No. 27. Wisconsin Department of
Natural Resources, Bureau of Fisheries
Management, Madison, Wisconsin.
75. Waldo, P. 1991. The geomorphic
approach to channel investigation. In
Proceedings of the Fifth Federal Interagency
Sedimentation Conference, Las Vegas,
Nevada.
76. Welsch, DJ. 1991. Riparian forest buffers.
Publication NA-PR-07-91. U.S. Depart-
ment of Agriculture, Forest Service,
Radnor, Pennsylvania.
77. Welsch, D.J., D.L. Smart et al. (Undated).
Forested wetlands: functions, benefits and the
use of best management practices. (Coordi-
nated with U.S. Natural Resources Conser-
vation Service, U.S. Army Corps of
Engineers, U.S. Environmental Protection
Agency, U.S. Fish and Wildlife Service,
U.S. Forest Service). Publication No. NA-
PR-01-95. U.S. Department of Agriculture,
Forest Service, Radnor, Pennsylvania.
Appendix A
A-29
-------
Additional Information:
Andrews, E.D. 1983. Entrainment of gravel
from naturally sorted riverbed material.
Geological Society of America 94: 1225-1231.
Arizona Riparian Council. 1990. Protection
and enhancement of riparian ecosystems (An
Annotated Bibliography). Phoenix, Arizona.
Coppin, N.J., and I.G. Richards. 1990. Use of
vegetation in civil engineering. Butterworths,
London, England.
Henderson, J.E., and F.D. Shields. 1984.
Environmental features for streambank protection
projects. Technical Report E-84-11. U.S. Army
Corps of Engineers Waterways Experiment
Station, Vicksburg, Mississippi.
Marble, A.D. 1992. A guide to wetland
functional design. Lewis Publishers, Boca
Raton, Florida.
Naiman, R.J. 1992. Watershed management.
Springer-Verlag, New York.
Pacific Rivers Council. 1993. Entering the
watershed. Washington, DC.
Schueler, T.R., P.A. Kumble, and M.A. Heraty.
1992. A current assessment of urban best
management practices. Washington
Metropolitan Council of Governments for
U.S. Environmental Protection Agency,
Washington, DC.
Short, H., and J. Ryan. 1995. The Winooski
River watershed evaluation project report.
AmericorpsCorporation for National and
Community Service, and U.S. Department of
Agriculture, Natural Resources Conservation
Service, Williston, Vermont.
U.S. Department of Agriculture, Soil Conserva-
tion Service. (Undated). Agriculture Informa-
tion Bulletin 460. Washington, DC.
U.S. Department of Agriculture, Natural
Resources Conservation Service. 1996.
Examining a 1930's case study summary:
restoration of the Winooski River watershed,
Vermont. Watershed Science Institute,
Burlington, Vermont.
Washington State Department of Ecology.
1992. Stormwater management manual for the
Puget Sound basin. Olympia, Washington.
Wisconsin Department of Natural Resources.
1995. Best management practices for water
quality. Bureau of Forestry, Madison, Wisconsin.
Wullstein, L.H., D. Duff, and J. McGurrin et al.
1995. Indexed bibliography on stream habitat
improvement. Trout Unlimited. U.S. Fish and
Wildlife Service, U.S. Forest Service, University
of Utah, Ogden, Utah.
A-30
Stream Corridor
-------
Appendix B
INCH-POUND / METRIC CONVERSION FACTORS
Length
Unit of measure
millimeter
centimeter
meter
kilometer
inch
foot
mile
Area
Unit of measure
square meter
hectare
square kilometer
square foot
acre
square mile
Volume
Unit of measure
cubic kilometer
cubic meter
liter
million U.S. gallons
acre-foot
cubic foot
gallon
Flow Rate
Unit of measure
cubic kilometers/year
cubic meters/second
liters/second
million U.S. gallons/day
U.S. gallons/minute
cubic feet/second
acre-feet/day
Temperature
Unit of measure
Fahrenheit
Celsius
Abbreviation
mm
cm
m
km
in
ft
mi
Abbreviation
rr,2
ha
km2
ft2
acre
mi2
Abbreviation
km3
rr,3
L
Mgal
acre-ft
ft3
gal
Abbreviation
km3/yr
m3/s (m3/sec)
Us (L/sec)
mgd (Mgal/d)
gpm (gal/min)
cfs (ft3/s)
acre-ft/day
Abbreviation
F
C
mm cm
1 0.1
10 1
1000 100
25.4 2.54
304.8 30.48
m2 ha
1
10000 1
1x106 100
0.093
4050 0.405
259
km3 m3
1 1x109
1
0.001
1233
0.0283
km3/yr m3/s
1 31.7
0.0316 1
0.001
0.044
0.0283
F
m
0.001
0.01
1
1000
0.0254
0.305
1609
km2
0.01
1
2.59
L
1000
1
28.3
3.785
L/s
1000
1
43.8
0.063
28.3
14.26
C
km
0.001
1
1.609
ft2
10.76
107600
1
43560
Mgal
1
0.3259
mgd
723
22.8
0.0228
1
0.647
0.326
in
0.0394
0.394
39.37
1
12
acre
2.47
247
1
640
acre-ft
811000
3.07
1
gpm
15800
15.8
694
1
449
226.3
ft
0.003
0.033
3.281
3281
0.083
1
5280
mfl
0.00386
0.386
0.00156
1
ft3
35.3
0.0353
134000
43560
1
0.134
cfs
1119
35.3
0.0353
1.547
0.0022
1
0.504
mi
0.621
1
gal
264
0.264
1x106
325848
7.48
1
acre-ft/day
2220
70.1
0.070
3.07
0.0044
1.985
1
.56 (after subtracting 32)
1.8 (then add 32)
Appendix B
A-31
-------
-------
Addendum
-------
-------
References
Abbe, IB., D.R. Montgomery, and C. Petroff.
1997. Design of stable in-channel wood debris
structures for bank protection and habitat
restoration: an example from the Cowlitz River,
WA. In Proceedings of the Conference on
Management of Landscape Disturbed by Channel
Incision, May 19-23.
Abt, S.R. 1995. Settlement and submergence
adjustments for Parshall flume. Journal of
Irrigation Drainage Engineering, ASCE 121(5):
317-321.
Ackers, P., and Charlton. 1970. Meandering
geometry arising from varying flows. Journal of
Hydrology 11 (3): 230-252.
Ackers P., and W.R. White. 1973. Sediment
transportnew approach and analysis. Ameri-
can Society of Civil Engineers Proc. Paper 10167.
Journal of the Hydraulics Division, ASCE
99(HY11): 2041 -2060.
Adams, W.J., R.A. Kimerle, and J. W. Barnett, Jr.
1992. Sediment quality and aquatic life
assessment. Environmental Science and
Technology 26(10): 1864-1875.
Adamus, PR. 1993. Irrigated wetlands of the
Colorado Plateau: information synthesis and
habitat evaluation method. EPA/600/R-93/071.
U.S. Environmental Protection Agency, Environ-
mental Research Laboratory, Corvallis, Oregon.
Aldridge, B.N., and J.M. Garrett. 1973. Roughness
coefficients for stream channels in Arizona. U.S.
Geological Survey Open-File Report. U.S.
Geological Survey.
Allan, J.D. 1995. Stream ecologystructure and
function of running waters. Chapman and Hall,
New York.
Allen, E.B. 1995. Mycorrhizal limits to rangeland
restoration: soil phosphorus and fungal species
composition. In Proceedings of the Fifth
International Rangeland Congress, Salt Lake
City, Utah.
Alonso, C.V., and ST. Combs. 1980. Channel
width adjustment in straight alluvial streams.
USDA-ARS: 5-31-5-40.
Alonso, C.V., F.D. Theurer, and D.W. Zachmann.
1996. Sediment Intrusion and Dissolved Oxygen
Transport ModelSIDO. Technical Report No. 5.
USDA-ARS National Sedimentation Laboratory,
Oxford, Mississippi.
American Public Health Association (APHA). 1995.
Standard methods for the examination of water
and wastewater. 19thed. American Public
Health Association, Washington, DC.
American Society for Testing Materials (ASTM).
1991. Standard methods for the examinations
of water and wastewater. 18th ed. American
Public Health Association, Washington, DC.
American Society of Civil Engineers (ASCE). 1997.
Guidelines for the retirement of hydroelectric
facilities.
Ames, C.R. 1977. Wildlife conflicts in riparian
management. In Importance, preservation and
management of riparian habitat, pp. 39-51.
USDA Forest Service General Technical Report
RM- 43. Rocky Mountain Forest and Range
Experiment Station. Fort Collins, Colorado.
Anderson, B.W., J. Dissano, D.L. Brooks, and R.D.
Ohmart. 1984. Mortality and growth of cotton-
wood on dredge-spoil. In California riparian
systems, eds. R.B. Warner and K.M. Hendrix,
pp. 438-444. University of California Press,
Berkeley.
Anderson, B.W., and S.A. Laymon. 1988. Creating
habitat for the Yellow-billed Cuckoo (Coccyzus
americana). In Proceedings of the California
riparian systems conference: protection,
management, and restoration for the 1990s,
coord. D.L. Abel, pp. 469-472. USDA Forest
Service General Technical Report PSW-110.
Pacific Southwest Forest and Range Experiment
Station, Berkeley, California. Pages 469-472.
Anderson, B.W., R.D. Ohmart, and J. Disano. 1978.
Revegetating the riparian floodplain for wildlife.
In Symposium on strategies for protection and
management of floodplain wetlands and other
riparian ecosystems, pp. 318-331. USDA Forest
Service General Technical Report WO-12.
References
B-1
-------
Andrews, E.D. 1980. Effective and bankfull
discharges of streams in the Yampa River Basin,
Colorado and Wyoming. Journal of Hydrology
46: 311-330.
Andrews, E.D. 1983. Entrainment of gravel from
natural sorted riverbed material. Geological
Society of America Bulletin 94: 1225-1231.
Andrews, E.D. 1984. Bed-material entrainment
and hydraulic geometry of gravel-bed rivers in
Colorado. Geological Society of America
Bulletin 97: 1012-1023.
Animoto, P.Y 1978. Erosion and sediment control
handbook. WPA 440/3-7-003. State of
California Department of Conservation,
Sacramento.
Apmann, R.P. 1972. Flow processes in open
channel bends. Journal of the Hydraulics
Division, ASCE 98(HY5): 795-810.
Apple, L.L., B.H. Smith, J.D. Dunder, and B.W.
Baker. 1985. The use of beavers for riparian/
aquatic habitat restoration of cold desert, gully-
cut stream systems in southwestern Wyoming.
G. Pilleri, ed. In Investigations on beavers,
G. Pilleri ed., vol. 4, pp. 123-130. Brain
Anatomy Institute, Berne, Switzerland.
Arcement, G.J., Jr., and V.R. Schneider. 1984.
Guide for selecting Manning's roughness
coefficients for natural channels and flood
plains. Federal Highway Administration
Technical Report No. FHWA-TS-4-204. U.S.
Department of Transportation, Federal Highway
Administration, Washington, DC.
Armour, C.L., and J.G. Taylor. 1991. Evaluation of
the Instream Flow Incremental Methodology by
U.S. Fish and Wildlife Service field users.
Fisheries 16(5).
Armour, C.L., and S.C. Williamson. 1988. Guid-
ance for modeling causes and effects in
environmental problem solving. U.S.. Fish and
Wildlife Service Biological Report 89(4).
Arnold, C, P. Boison, and P. Patton. 1982. Sawmill
Brook: an example of rapid geomorphic change
related to urbanization. Journal of Geology 90:
155-166.
Aronson, J.G., and S.L Ellis. 1979. Monitoring,
maintenance, rehabilitation and enhancement
of critical Whooping Crane habitat, Platte River,
Nebraska. In The mitigation symposium: a
national workshop on mitigating losses of fish
and wildlife habitats, tech. coord. G.A.
Swanson, pp. 168- 180. USDA Forest Service
General Technical Report. RM-65. Rocky
Mountain Forest and Range Experiment Station,
Fort Collins, CO.
Ashmore, P.E., T.R. Yuzyk, and R. Herrington. 1988.
Bed-material sampling in sand-bed streams.
Environment Canada Report IWD-HQ-WRB-SS-
88-4. Environment Canada, Inland Waters
Directorate, Water Resources Branch, Sediment
Survey Section.
Atkins, J.B., and J.L. Pearman. 1994. Low-flow
and flow-duration characteristics of Alabama
streams. U.S. Geological Survey Water-
Resources Investigations Report 93-4186.
U.S. Geological Survey.
Averett, R.C., and U. Schroder. 1993. A guide to
the design of surface-water-quality studies. U.S.
Geological Survey Open-File Report 93-105.
U.S. Geological Survey.
Baird, K.J. and J.P. Rieger. 1988. A restoration
design for Least Bell's Vireo habitat in San Diego
County. In Proceedings of the California riparian
systems conference: protection, management,
and restoration the 1990s, coord. D.L. Abell, pp.
462-467. USDA Forest Service General Technical
Report PSW-110. Pacific Southwest Forest and
Range Experiment Station, Berkeley, California.
Baker, B.W., D.L. Hawksworth, and J.G. Graham.
1992. Wildlife habitat response to riparian
restoration on the Douglas Creek watershed. In
Proceedings of the Fourth Annual Conference,
Colorado Riparian Association, Steamboat
Springs, Colorado.
Barinaga, M. 1996. A recipe for river recovery?
Science 273: 1648-1650.
Barnes, H. 1967. Roughness characteristics of
natural channels. U.S. Geological Survey Water
Supply paper 1849. U.S. Government Printing
Office, Washington, DC.
B-2
Stream Corridor
-------
Barron, R. 1989. Protecting the Charles River
corridor. National Wetlands Newsletter, May-
June: 8-10.
Bartholow, J.M., J.L Laake, C.B. Stalnaker, S.C.
Williamson. 1993. A salmonid population
model with emphasis on habitat limitations.
Rivers 4: 265-279.
Bathurst, J.C. 1985. Literature review of some
aspects of gravel-bed rivers. Institute of
Hydrology, Wallingford, Oxfordshire, U.K.
Bay ley, P. B. 1995. Understanding large river-
floodplain ecosystems. BioSdence 45(3): 154.
Bayley, P.B., and H.W. Li. 1992. Riverine fishes. In
The rivers handbook, ed. P. Calow and G.E.
Petts, vol. 1, pp. 251-281. Blackwell Scientific
Publications, Oxford, U.K.
Begin, Z.B. 1981. Stream curvature and bank
erosion: a model based on the momentum
equation. Journal of Ecology 89: 497-504.
Behmer, D.J., and C.P. Hawkins. 1986. Effects of
overhead canopy on macroinvertebrate produc-
tion in a Utah stream. Freshwater Biology 16(3):
287-300.
Behnke, R.J., and R.F. Raleigh. 1978. Grazing and
the riparian zone: impact and management
perspectives. In Strategies for protection of
floodplain wetlands and other riparian ecosys-
tems, tech. coords. R.R. Johnson and J.F.
McCormick, pp. 263-267. USDA Forest Service
General Technical Report WO-12. U.S. Depart-
ment of Agriculture, Forest Service.
Belt, G.H., J. O'Laughlin, and I Merrill. 1992.
Design of forest riparian buffer strips for the
protection of water quality: analysis of scientific
literature. Report No. 8. Idaho Forest, Wildlife
and Range Policy Analysis Group, Idaho Forest,
Wildlife and Range Experiment Station, Moscow,
Idaho.
Benke, A.C., T.C. Van Arsdall, Jr., D.M. Gillespie,
and F.K. Parrish. 1984. Invertebrate productivity
in a subtropical blackwater river: the importance
of habitat and life history. Ecological Mono-
graphs 54: 25-63.
Benson, M.A., and T. Dalrymple. 1967. General
field and office procedures for indirect discharge
measurements. In Techniques of water-resources
investigations of the United States Geological
Survey, Book 3, Chapter A1.
Beschta, R. 1984. TEMP84: A computer model for
predicting stream temperatures resulting from
the management of streamside vegetation.
Report WSDG-AD-00009, USDA Forest Service,
Watershed Systems Development Group, Fort
Collins, Colorado. U.S. Department of Agricul-
ture, Forest Service.
Beschta, R.L., W.S. Platts, J.B. Kauffman, and M.T.
Hill. 1994. Artificial stream restorationmoney
well spent or an expensive failure? In Proceed-
ings on Environmental Restoration, Universities
Council on Water Resources 1994 Annual
Meeting, August 2-5, Big Sky, Montana, pp. 76-
104.
Bettess, R., and W.R. White. 1987. Extremal
hypotheses applied to river regime. In Sediment
transport in gravel-bed rivers, ed. C.R. Thorne,
J.C. Bathurst, and R.D. Hey, pp. 767-789. John
Wiley and Sons, Inc., Chichester, U.K.
Biedenharn, D.S., C.M. Elliott, and C.C. Watson.
1997. The WES stream investigation and
streambank stabilization handbook. Prepared
for U.S. Environmental Protection Agency by
U.S. Army Corps of Engineers, Waterways
Experiment Station, Vicksburg, Mississippi.
Biedenharn, D.S., and C.R. Thorne. 1994.
Magnitude-frequency analysis of sediment
transport in the Lower Mississippi River. Regu-
lated Rivers: Research and Management 9(4):
237-251.
Bio West. 1995. Stream Habitat Improvement
Evaluation Projec. Bio West, Logan, Utah.
Bisson, R.A., R.E. Bilby, M.D. Bryant, C.A. Dolloff,
G.B. Grette, R.A. House, M.J. Murphy, K V.
Koski, and J.R. Sedell. 1987. Large woody
debris in forested streams in the Pacific North-
west: past, present, and future. In Streamside
management: forestry and fishery interactions,
ed. E.O. Salo and T.W. Cundy, pp. 143-190.
Institute of Forest Resources, University of
Washington, Seattle, Washington.
References
B-3
-------
Blench, T. 1957. Regime behavior of canals and
rivers. Butterworths Scientific Publications,
London.
Blench, T. 1969. Coordination in mobile-bed
hydraulics. Journal of the Hydraulics
Division,ASCE 95(HY6): 1871 -98.
Bond, C.E. 1979. Biology of Fishes. Saunders
College Publishing, Philadelphia, Pennsylvania.
Booth, D., and C. Jackson. 1997. Urbanization of
aquatic systems: degradation thresholds,
stormwater detection and the limits of mitiga-
tion. Journal AWRA 33(5): 1077-1089.
Booth, D., D. Montgomery, and J. Bethel. 1996.
Large woody debris in the urban streams of the
Pacific Northwest. In Effects of watershed
development and management on aquatic
systems, ed. L. Rosner, pp. 178-197. Proceed-
ings of Engineering Foundation Conference,
Snowbird, Utah, August 4-9.
Bourassa, N., and A. Morin. 1995. Relationships
between size structure of invertebrate assem-
blages and trophy and substrate composition in
streams. Journal of the North American
Benthological Society, 14: 393-403.
Bovee, K.D. 1982. A guide to stream habitat
analysis using the instream flow incremental
methodology. Instream Flow Information Paper
No. 12 FWS/OBS-82-26. U.S. Fish and Wildlife
Service, Biological Services Program, Fort Collins,
Colorado.
Bovee, K.D., T.J. Newcomb, and T.J. Coon. 1994.
Relations between habitat variability and
population dynamics of bass in the Huron River,
Michigan. National Biological Survey Biological
Report 22. National Biological Survey.
Bowie, G. L., W.B. Mills, D.B. Porcella, C.L.
Campbell, J.R. Pagenkopf, G.L. Rupp, K.M.
Johnson, P.W. H. Chan, and S.A. Gherini. 1985.
Rates, constants, and kinetics formulations in
surface water quality modeling, 2d ed. EPA/600/
3-85/040. U.S. Environmental Protection Agency,
Environmental Research Laboratory, Athens,
Georgia.
Brady, W., D.R. Patton, and J. Paxson. 1985. The
development of southwestern riparian gallery
forests. In Riparian ecosystems and their
management: reconciling conflicting uses, tech.
coords. R.R. Johnson et al., pp. 39-43. USDA
Forest. Service General Technical Report RM-120,
Rocky Mountain Forest and Range Experiment
Station, Fort Collins, Colorado.
Bramblett, R.G., and K.D. Fausch. 1991. Variable
fish communities and the Index of Biotic
Integrity in a western Great Plains river. Transac-
tions of the American Fisheries Society 120:
752-769.
Brazier, J.R., and G.W. Brown. 1973. Buffer strips
for stream temperature control. Research Paper
15, Paper 865. Oregon State University, School
of Forestry, Forest Research Laboratory, Corvallis.
Briggs, J.C. 1986. Introduction to the zoogeogra-
phy of North American fishes. In Zoogeography
of North American Freshwater Fishes, ed. C.H.
Hocuttand E.O. Wiley, pp. 1-16. Wiley
Interscience, New York.
Briggs, M.K. 1992. An evaluation of riparian
vegetation efforts in Arizona. Master's thesis,
University of Arizona, School of Renewable
Natural Resources.
Briggs, M.K., B.A. Roundy, and W.W. Shaw. 1994.
Trial and errorassessing the effectiveness of
riparian revegetation in Arizona. Restoration and
Management Notes 12(2): 160-167.
Brinson, M. 1995. The HGM approach explained.
National Wetlands Newsletter, November-
December 1995: 7-13.
Brinson, M.M., F.R. Hauer, L.C. Lee, W.L. Nutter,
R.D. Rheinhardt, R.D. Smith, and D. Whigham.
1995. A guidebook for application of
hydrogeomorphic assessments to riverine
wetlands. Technical Report WRP-DE-11. U.S.
Army Corps of Engineers, Waterways Experi-
ment Station, Vicksburg, Mississippi.
Brinson, M.M., B.L. Swift, R.C. Plantico, and J.S.
Barclay. 1981. Riparian ecosystems: their
ecology and status. FWS/OBS-81/17. U.S. Fish
and Wildlife Service, Office of Biological
Services, Washington, DC.
B-4
Stream Corridor
-------
Brookes, A. 1987. Restoring the sinuosity of
artificially straightened stream channels.
Environmental Geology Water Science 10(1):
33-41.
Brookes, A. 1988. Channelized rivers: perspectives
for environmental management. John Wiley and
Sons, Ltd., Chichester, U.K.
Brookes, A. 1990. Restoration and enhancement of
engineered river channels: some European
experiences. Regulated Rivers: Research &
Management 5(1): 45-56.
Brookes, A. 1991. Design practices for channels
receiving urban runoff: examples from the river
Thames catchment, UK. Paper given at Engineer-
ing Foundation Conference, Mt. Crested Butte,
Colorado, August.
Brookes, A. 1995. The importance of high flows for
riverine environments. In The ecological basis for
river management, ed. D.M. Harper and A.J.D.
Ferguson. John Wiley and Sons, Ltd.,
Chichester, U.K.
Brooks, R.P., E.D. Bellis, C.S. Keener, M.J.
Croonquist, and D.E. Arnold. 1991. A method-
ology for biological monitoring of cumulative
impacts on wetland, stream, and riparian
components of watershed. In Proceedings of an
international symposium: Wetlands and River
Corridor Management, July 5-9, 1989, Charles-
ton, South Carolina, ed. J.A. Kusler and S. Daly,
pp. 387-398.
Brown, G.W., and J.T. Krygier. 1970. Effects of
clear-cutting on stream temperature. Water
Resources Research 6: 1133-1139.
Brownlie, W.R. 1981. Prediction of flow depth and
sediment discharge in open channels. Report
No. KH-R-43A. California Institute of Technol-
ogy, W.M. Keck Laboratory of Hydraulics and
Water Resources, Pasadena.
Brouha, P. 1997. Good news for U.S. fisheries.
Fisheries 22: 4.
Brungs, W.S., and B.R. Jones. 1977. Temperature
Criteria for Freshwater Fish: Protocols and
Procedures. EPA-600/3-77-061. Environ.
Research Lab, Ecological Resource Service, U.S.
Environmental Protection Agency, Office of
Research and Development, Deluth, MN.
Brush, T. 1983. Cavity use by secondary cavity-
nesting birds and response to manipulations.
Condor 85: 461 -466.
Bryant, M.D. 1995. Pulsed monitoring for
watershed and stream restoration. Fisheries
Buchanan, T.J., and W.P. Somers. 1969. Discharge
measurements at gaging stations. Techniques of
water-resources investigations of the United
States Geological Survey, Book 3, Chapter A8.
Budd, W.W., PL. Cohen, PR. Saunders, and F.R.
Steiner. 1987. Stream corridor management in
the Pacific Northwest: I. determination of stream
corridor widths. Environmental Management 1 1 :
587-597.
Burrows, W.J., and D.J. Carr. 1969. Effects of
flooding the root system of sunflower plants on
the cytokinin content in the xylem sap.
Physiologia Plantarum 22: 1 105-1 1 12.
Call, M.W. 1970. Beaver pond ecology and beaver
trout relationships in southeastern Wyoming.
Ph.D. dissertation, University of Wyoming,
Laramie.
Carling, P. 1988. The concept of dominant
discharge applied to two gravel-bed streams in
relation to channel stability thresholds. Earth
Surface Processes and Landforms 13: 355-67.
Carothers, S.W. 1979. Distribution and abundance
of nongame birds in riparian vegetation in
Arizona. Final report to USDA Forest Service,
Rocky Mountain Forest and Range Experimental
Station, Tempe, Arizona.
Carothers, S.W., and R.R. Johnson. 1971. A
summary of the Verde Valley breeding bird
survey, 1970. Completion report FW 16-10:
46-64. Arizona Game and Fish Department.
References
B-5
-------
B-6
Carothers, S.W., R.R. Johnson, and S.W. Aitchison.
1974. Population structure and social
organization of southwestern riparian birds.
American Zoology 14: 97-108.
Carothers, S.W., G.S. Mills, and R.R. Johnson.
1990. The creation and restoration of riparian
habitats in southwestern arid and semi-arid
regions. Wetland creation and restoration: the
status of the science, vol. 1, regional reviews,
ed. J. A. Kusler and M. E. Kentula, pp. 359-376.
Island Press, Covelo, California.
Carson, M.A., and M.J. Kirkby. 1972. Hillslope
form and process. Cambridge University Press,
London.
Cavendish, M.G., and M.I. Duncan. 1986. Use of
the instream flow incremental methodology: a
tool for negotiation. Environmental Impact
Assessment Review 6: 347-363.
Center for Watershed Protection. 1995. Water-
shed protection techniques, vol. 1, no. 4.
Center for Watershed Protection, Silver Spring,
Maryland. Summer.
Chaney, E., W. Elmore, and W.S. Platts. 1990.
Livestock grazing on western riparian areas. U.S.
Environmental Protection Agency, Region 8.
Chang, H.H. 1988. Fluvial processes in river
engineering. John Wiley and Sons, Ltd., New
York.
Chang, H.H. 1990. Generalized computer
program FLUVIAL-12, mathematical model for
erodible channels, user's manual. April.
Chapman, D. W. 1988. Critical review of variables
used to define effects of fines in reeds of large
salmonids. Transactions American Fisheries
Society 1171-21.
Chapman, R.J., T.M. Hinckley, L.C. Lee, and R.O.
Teskey. 1982. Impact of water level changes on
woody riparian and wet/and communities, vol.
X. FWS/OBS-82/23. Fish and Wildlife Service.
Chen, W.F. 1975. Limit analysis and soil plasticity.
Elsevier Scientific Publishing Co., New York.
Chitale, S.V. 1973. Theories and relationships of
river channel patterns. Journal of Hydrology
19(4): 285-308.
Chow, V.T. 1959. Open channel hydraulics.
McGraw-Hill, Inc., New York.
Chow, Ven-te, 1964. Handbook of Applied
Hydrology, a Comparison of Water-Resources
Technology. McGraw Hill, New York.
Clary, W.P., and B.F. Webster. 1989. Managing
grazing of riparian areas in the intermountain
region. USDA Forest Service General Technical
Report INT-263. USDA Forest Service, Inter-
mountain Research Station, Ogden, Utah.
Colby, B.R. 1964. Practical computations of bed
material discharge. Journal of the Hydraulics
Division, ASCE 90(HY2).
Cole, G.A. 1994. Textbook of limnology, 4th ed.
Waveland Press, Prospect Heights, Illinois.
Cole, D.N., and J.L. Marion. 1988. Recreation
impacts in some riparian forests of the eastern
United States. Environmental Management 12:
99-107.
Collier, R.H. Webb, and J.C. Schmidt. 1996. Dams
and rivers: A primer on the downstream effects
of dams. U.S. Geological Survey Circular vol.
1126 (June).
Collins, T.C. 1976. Population characteristics and
habitat relationships of beavers, Castor
canadensis, in northwest Wyoming. Ph.D.
dissertation, University of Wyoming, Laramie.
Conroy, S. D., and T. J. Svejcar. 1991. Willow
planting success as influenced by site factors
and cattle grazing in northeastern California.
Journal of Range Management 44 (1): 59-63.
Cooper, A. C. 1965. The effect of transported
stream sediments on survival of sockeye and
pink salmon eggs and alevin. Int. Pac. Salmon
Fish. Comm., Bulletin No. 18.
Cooper, CM,, and S.S. Knight. 1987. Fisheries in
man-made pools below grade-control structures
and in naturally occurring scour holes of
unstable streams. Journal of Soil and Water
Conservation 42(5): 370-373.
Stream Corridor
-------
Copeland, R.R. 1994. Application of channel
stability methodscase studies. Technical Report
HL-94-11, U.S. Army Corps of Engineers,
Waterways Experiment Station, Vicksburg, MS.
Coppin, N.J., and I.G. Richards. 1990. Use of
vegetation in civil engineering. Construction
Industry Research and Information Association
(CIRIA), London. ISBN 0-408-03849-7.
Couch, C. 1997. Fish dynamics in urban streams
near Atlanta, Georgia. Technical Note 94.
Watershed Protection Techniques 2(4):511-514.
Covich. 1993. Water and ecosystems. In Water in
crisis: A guide to the World's Freshwater
resources, ed. P.M. Gleick. Oxford University
Press, Oxford, United Kingdom.
Cowan, J. 1959. 'Pre-fab'wire mesh cone gives
doves better nest than they can build them-
selves. Outdoor California 20: 10-11.
Cowardin, L.W., V. Carter, F.C. Golet, and E.T.
LaRoe. 1979. Classification of wetlands and
deep water habitats of the United States. U.S.
Fish and Wildlife Service, Washington, DC.
Crawford, J., and D. Lenat. 1989. Effects of land
use on water quality and the biota of three
streams in the Piedmont Province of North
Carolina. U.S. Geological Survey Water Re-
sources Investigations Report 89-4007. U.S.
Geological Survey, Raleigh, North Carolina.
Croonquist, M.J., and R.P. Brooks. 1991. Use of
avian and mammalian guilds as indicators of
cumulative impacts in riparian-wetland areas.
Environmental Management 15: 701-714.
Cross, S.P. 1985. Responses of small mammals to
forest perturbations. Pages 269-275 in R.R.
Herman, R.L. and F.P. Meyer. 1990. Fish Kills
Due to Natural Causes. In F.P. Field Manual for
the Investigation of Fish Kills. F.P. Meyer and
L.A. Barcaly (Eds.). United States Department of
the Interior, Fish and Wildlife Service, Arlington,
Virginia.
Cummins, K.W. 1974. The structure and function
of stream ecosystems. BioScience 24:631-641.
Darby, S.E., and C.R. Thorne. 1992. Approaches to
modelling width adjustment in curved alluvial
channels. Working Paper 20, Department of
Geography, University of Nottingham, U.K.
Darby, S.E., and C.R. Thorne. 1996. Numerical
simulation of widening and bed deformation of
straight sand-bed rivers. Journal of Hydraulic
Engineering 122:184-193. ISSN 0733-9429.
DeBano, L.F., and U. Schmidt. 1989. Improving
southwestern riparian areas through water and
management. USDA Forest Service, General
Technical Report RM-182. U.S. Department of
Agriculture, Forest Service.
Department of the Interior (DOI), Department of
Commerce, and Lower Elwha S'Klallam Tribe.
1994. The Elwha report: restoration of the
Elwha River ecosystem and native anadromous
fisheries. U.S. Government Printing Office 1994-
590-269.
Dickason, C. 1988. Improved estimates of ground
water mining acreage. Journal of Soil and
Water Conservation 43(1988): 239-240.
Dirr, M.A., and C.W. Heuser. 1987. The reference
manual of woody plant propagation. Varsity
Press, Athens, Georgia.
Dissmeyer, G.E. 1994. Evaluating the effectiveness
of forestry best management practices in
meeting water quality goals or standards. USDA
Forest Service Miscellaneous Publication 1520,
Southern Region, Atlanta, Georgia.
Dolloff, C.A., PA. Flebbe, and M.D. Owen. 1994.
Fish habitat and fish populations in a southern
Appalachian watershed before and after
Hurricane Hugo. Transactions of the American
Fisheries Society 123(4): 668-678.
Downs, P.W. 1995. River channel classification for
channel management purposes. In Changing
river channels, ed. A. Gurnell and G. Petts. John
Wiley and Sons, Ltd., New York.
Dramstad, W.E., J.D. Olson and R.T. Gorman.
1996. Landscape ecology principles in land-
scape architecture and land-use planning. Island
Press, Washington, DC.
References
B-7
-------
Dubos, R. 1981. Celebration of life. McGraw-Hill,
New York.
Dunne, I, and L.B. Leopold. 1978. Water in
environmental planning. W.H. Freeman Co.,
San Francisco.
Dunne, T. 1988. Geomorphologic contributions to
flood control planning. In Flood geomorphology,
pp. 421-438. John Wiley and Sons, Ltd., New
York.
Dunster, J., and K. Dunster. 1996. Dictionary of
natural resource management. University of
British Columbia. April. ISBN: 077480503X.
Dury, G.H. 1973. Magnitude-frequency analysis
and channel morphology. In Fluvial Geomor-
phology, ed. M. Morisaua, pp. 91-121. Allen &
Unwin.
Edminster, F.C., and W.S. Atkinson. 1949.
Streambank erosion control on the Winooski
River, Vermont. USDA Circular No. 837. U.S.
Department of Agriculture, Washington, DC.
Einstein, H.A. 1950. The bed-load function for
sediment transportation in open channel flows.
U.S. Department of Agriculture Technical
Bulletin 1026. U.S. Department of Agriculture,
Washington, DC.
Electric Power Research Institute (EPRI). 1996.
EPRI's CompMech suite of modeling tools
population-level impact assessment. Publication
W03221. Electric Power Research Institute, Palo
Alto, California.
Elmore, W., and R.L. Beschta. 1987. Riparian areas:
perceptions in management. Rangelands 9:
260-265.
Elmore, W., and J.B. Kauffman. 1994. Riparian and
watershed systems: degradation and restora-
tion. In Ecological implications of livestock
herbivory in the West, ed. M. Vavra, W.A.
Laycock, and R.D. Piper, pp. 211-232. Society
for Range Management, Denver, CO.
Emmett, W.M. 1975. The channels and waters of
the Upper Salmon River Area, Idaho. USGS
Professional Paper 870-A, Washington, D.C.
Engelund, F, and E. Hansen. 1967. A monograph
on sediment transport in alluvial streams. Danish
Technical Press (Teknisk Forlag).
Entry, J.A., P.K. Donnelly, and W.H. Emmingham.
1995. Atrazine and 2,4-D mineralization in
relation to microbial biomass in soils of young-,
second-, and old-growth riparian forests.
Applied Soil Ecology 2: 77-84.
Erman, N.A. 1991. Aquatic invertebrates as
indicators of biodiversity. In Proceedings of a
Symposium on Biodiversity of Northwestern
California, Santa Rosa, California. University of
California, Berkeley.
Fan, S.S., ed. 1988. Twelve selected computer
stream sedimentation models developed in the
United States. In Proceedings of the Interagency
Symposium on Computer Stream Sedimentation
Models, Denver, CO, October 1988. Federal
Energy Regulatory Commission, Washington,
DC.
Fan, S.S., and B.C. Yen, eds. 1993. Report on the
Second Bilateral Workshop on Understanding
Sedimentation Processes and Model Evaluation,
San Francisco, CA, July 1993. Proceedings
published by the Federal Energy Regulatory
Commission, Washington, DC.
Fausch, K.D., J.R. Karr, and PR. Yant. 1984.
Regional association of an Index of Biotic
Integrity based on stream fish communities.
Transactions of the American Fisheries Society
113: 39-55.
Federal Energy Regulatory Commission (FERC).
1996. Reservoir release requirements for fish at
the New Don Pedro Project, California. Final
Environmental Impact Statement. Office of
Hydropower Licensing, FERC-EIS-0081F.
Federal Interagency Sedimentation Project. 1986.
Catalog of instruments and reports for fluvial
sediment investigations. Federal Inter-Agency
Sedimentation Project, Minneapolis, Minnesota.
Feminella, J.W., and W.J. Matthews. 1984.
Intraspecific differences in thermal tolerance of
Etheostoma spectabile (Agassiz) in constant
versus fluctuating environments. Journal of
Fisheries Biology 25: 455-461.
B-8
Stream Corridor
-------
Fennessey, N.M., and R.M. Vogel. 1990. Regional
flow-duration curves for ungaged sites in
Massachusetts. Journal of Water Resources
Planning and Management, ASCE 116 (4):
530-549.
Ferguson, B.K. 1991. Urban stream reclamation.
Journal of Soil and Water Conservation 46(5):
324-328.
Flessner, T.R., D.C. Darris, and S.M. Lambert. 1992.
Seed source evaluation of four native riparian
shrubs for streambank rehabilitation in the
Pacific Northwest. In Symposium on ecology
and management of riparian shrub communi-
ties, pp. 155-162. USDA Forest Service General
Technical Report INT-289. U.S. Department of
Agriculture, Forest Service.
Flosi, G., and F.L. Reynolds. 1994. California
salmonid stream habitat restoration manual.
2nd ed. California Department of Fish and
Game, Sacramento.
Fogg, J.L. 1995. River channel restoration: guiding
principles for sustainable projects, ed. A.
Brookes and F.D. Shields. John Wiley and Sons.
ISBN: 0471961396.
Fordham, A.J., and L.S. Spraker. 1977. Propaga-
tion manual of selected gymnosperms. Arnoldia
37: 1-88.
Forman, R.T.T. 1995. Land mosaics: the ecology of
landscapes and regions. Cambridge University
Press, Great Britain.
Forman, R.T.T., and M. Godron. 1986. Landscape
ecology. John Wiley and Sons, New York.
Fortier, S., and F.C. Scobey. 1926. Permissible canal
velocities. Transactions of the ASCE 89:
940-956.
Francfort, J.E., G.F. Cada, D.D. Dauble, R.T. Hunt,
D.W. Jones, B.N. Rinehart, G.L Sommers, and
R.J. Costello. 1994. Environmental mitigation
at hydroelectric projects. Vol. II. Benefits and
costs of fish passage and protection. DOE/ID-
10360(V2). Prepared for U.S. Department of
Energy, Idaho Operations Office by Idaho
National Engineering Laboratory, EG&G Idaho,
Inc., Idaho Falls, Idaho.
Fredrickson, L.H. 1978. Lowland hardwood
wetlands: current status and habitat values for
wildlife. In Wetland functions and values: the
state of our understanding, ed. P.E. Greeson,
V.R. Clark, and J.E. Clark. American Water
Resources Association, Minneapolis, Minnesota.
Fredrickson, L.H., and T.S. Taylor. 1982. Manage-
ment of seasonally flooded impoundments for
wildlife. U.S. Fish and Wildlife Service Resource
Publication 148. U.S. Fish and Wildlife Service.
French, R.H. 1985. Open-channel hydraulics.
McGraw-Hill Publishing Co., New York.
Fretwell, S.D., and HI. Lucas. 1970. On territorial
behavior and other factors influencing habitat
distribution in birds. I. Theoretical development.
Acta Biotheoretica 19: 16-36.
Friedman, J.M., M.L. Scott, and W.M. Lewis, Jr.
1995. Restoration of riparian forests using
irrigation, disturbance, and natural seedfall.
Environmental Management 19: 547-557.
Frissell, C.A., W.L. Liss, C.E. Warren, and M.D.
Hurley. 1986. A hierarchial framework for
stream habitat classification: viewing streams in
a watershed context. Environmental Manage-
ment 10:199-214.
Galli, J. 1991. Thermal impacts associated with
urbanization and stormwater best management
practices. Metropolitan Washington Council of
Governments, Maryland Department of Environ-
ment, Washington, DC.
Garcia, M.H., L. Bittner, and Y. Nino. 1994.
Mathematical modeling of meandering streams
in Illinois: a tool for stream management and
engineering. Civil Engineering Studies, Hydraulic
Engineering Series No. 43, University of Illinois,
Urbana.
Garcia de Jalon, D. 1995. Management of physical
habitat for fish stocks. In The ecological basis
for river management, ed. D.M. Harper and J.D.
Ferguson, pp. 363-374. John Wiley & Sons,
Chichester.
Gebert, W.A., D.J. Graczyk, and W.R. Krug. 1987.
Average annual runoff in the United States,
1951-80. Hydrological Investigations Atlas.
HA-710. U.S. Geological Survey, Reston, Virginia.
References
B-9
-------
Glasgow, L. and R. Noble. 1971. The importance of
bottomland hardwoods to wildlife. Pages
30-43 in Proceedings of the Symposium on
Southeast Hardwoods, Dothan, Alabama, pp.
30-43. U.S. Department of Agriculture, Forest
Service.
Gilbert, R.O. 1987. Statistical methods for
environmental pollution monitoring.
VanNostrand Reinhold, New York.
Goldman, S.J., K. Jackson, and T.A. Bursztynsky.
1986. Erosion and sediment control handbook.
McGraw Hill Book Company, New York.
Goldner, B.H. 1984. Riparian restoration efforts
associated with structurally modified flood
control channels. In California riparian systems,
ed. R.B. Warner and K.M. Hendrix, pp. 445-451.
University of California Press, Berkeley.
Gomez, B. and M. Church. 1989. An assessment
of bedload transport formulae for gravel bed
rivers. Water Resources Research 25(6):
1161-1186.
Gordon, N.D., T.A. McMahon, and B.L. Finlayson.
1992. Stream hydrology: an introduction for
ecologists. John Wiley & Sons, Chichester, U.K.
Gosselink, J.G., G.P. Shaffer, L.L. Lee, D.M. Burdick,
D.L. Childres, N.C. Leibowitz, S.C. Hamilton, R.
Boumans, D. Cushman, S. Fields, M. Koch, and
J.M. Visser. 1990. Landscape conservation in a
forested watershed: can we manage cumulative
impacts? BioSdence 40(8): 588-600.
Grant, G.E., FJ. Swanson, and M.G. Wolman.
1990. Pattern and origin of stepped-bed
morphology in high-gradient streams, Western
Cascades, Oregon. Geological Survey of America
Bulletin 102:340-352.
Gregory, K., R. Davis and P. Downs. 1992. Identi-
fication of river channel change due to urbaniza-
tion. Applied Geography 12:299-318.
Gregory, S.V., FJ. Swanson, W.A.McKee, and K.W.
Cummins. 1991. An ecosystem perspective on
riparian zones. Bioscience 41:540-551.
Griffiths, G.A. 1981. Stable-channel design in
gravel-bed rivers. Journal of Hydrology 52(3/4):
291-305.
Grissinger, E.H., W.C. Little, and J.B. Murphey.
1981. Erodibility of streambank materials of low
cohesion. Transactions of the American Society
of Agricultural Engineers 24(3): 624-630.
Guy and Norman. 1982. Techniques for water-
resource investigations, field measures for
measurement of fluvial sediment. U.S.
Geological Survey.
Haan, C.T., B.J. Barfield, and J.C. Hayes. 1994.
Design hydrology and sedimentation for small
catchments. Academic Press, San Diego.
Hackney, C.T., S.M. Adams, and W.H. Martin, eds.
1992. Biodiversity of the southeastern United
states: aquatic communities. John Wiley and
Sons, New York.
Haferkamp, M.R., R.F. Miller, and FA. Sneva. 1985.
Seeding rangelands with a land imprinter and
rangeland drill in the Palouse Prairie and
sagebrush-bunchgrass zone. In Proceedings of
Vegetative Rehabilitation and Equipment
Workshop, U.S. Forest Service, 39th Annual
Report, Salt Lake City, Utah, pp. 19-22.
Hagerty, D.J. 1991. Piping/sapping erosion I: basic
considerations. Journal of Hydraulic Engineering
117(8): 997-998.
Hammitt, W.E., and D.N. Cole. 1987. Wildland
recreation: ecology and management. John
Wiley and Sons, New York.
Handy, R.L., and J.S. Fox. 1967. A soil borehole
direct-shear test device. Highway Research
News 27: 42-51.
Hansen, PL., R.D. Pfister, K. Boggs, B.J. Cook, J. Joy,
and D.K. Hinckley. 1995. Classification and
management of Montana's riparian and wetland
sites. Montana Forest and Conservation
Experiment Station, School of Forestry, University
of Montana. Miscellaneous Publication No. 54.
Missoula.
B-10
Stream Corridor
-------
Harrelson, C.C., C.L. Rawlins, and J.P. Potyondy.
1994. Stream channel reference sites: an
illustrated guide to field technique. General
Report No. RM-245. U.S. Department of
Agriculture, Forest Service, Fort Collins,
Colorado.
Harris, L.D. 1984. The fragmented forest. Univer-
sity of Chicago Press, Chicago, Illinois.
Hartmann, H., and D.E. Kester. 1983. Plant
propagation: principles and practice. Prentice-
Hall, Englewood Cliffs, New Jersey.
Hartman, G., J.C. Scrivener, L.B. Holtby, and
L. Powell. 1987. Some effects of different
streamside treatments on physical conditions
and fish population processes in Carnation
Creek, a coastal rain forest stream in British
Columbia. In Streamside management: forestry
and fishery interactions, ed. E.O. Salo and T.W.
Cundy, pp. 330-372. Inst. of Forest Resources,
University of Washington, Seattle.
Hasfurther, V.R. 1985. The use of meander
parameters in restoring hydrologic balance to
reclaimed stream beds. In The restoration of
rivers and streams: theories and experience, ed.
J.A. Gore. Butterworth Publishers, Boston.
Heiner, B.A. 1991. Hydraulic analysis and modeling
of fish habitat structures. American Fisheries
Society Symposium 10: 78-87.
Helwig, PC. 1987. Canal design by armoring
process. In Sediment transport in gravel-bed
rivers, ed. C.R. Thorne, J.C. Bathurst, and R.D.
Hey. John Wiley and Sons, Ltd., New York.
Hemphill, R.W., and M.E. Bramley 1989. Protection
of river and canal banks. Construction Industry
Research and Information Association/
Butterworths, London.
Henderson, P.M. 1966. Open channel flow. The
Macmillan Company, New York.
Henderson, J.E. 1986. Environmental designs for
streambank protection projects. Water
Resources Bulletin 22(4): 549-558.
Hey, R.D. 1975. Design discharge for natural
channels. In Science, Technology and Environ-
mental Management, ed. R.D. Hey and T.D.
Davies, pp. 73-88. Saxxon House, Farnborough.
Hey, R.D. 1976. Geometry of river meanders.
Nature 262: 482-484.
Hey, R.D. 1988. Mathematical models of channel
morphology. In Modeling geomorphological
systems, ed. M.G. Anderson, pp. 99-126. John
Wiley and Sons, Chichester
Hey, R.D. 1990. Design of flood alleviation
schemes: Engineering and the environment.
School of Environmental Sciences, University of
East Anglia, Norwich, United Kingdom.
Hey, R.D. 1994. Restoration of gravel-bed rivers:
principles and practice. In "Natural" channel
design: perspectives and practice, ed. D.
Shrubsole, pp. 157-173. Canadian Water
Resources Association, Cambridge, Ontario.
Hey, R.D. 1995. River processes and management.
In Environmental science for environmental
management, ed. T. O'Riordan, pp. 131-150.
Longman Group Limited, Essex, U.K., and John
Wiley, New York.
Hey, R.D., and C.R. Thorne. 1986. Stable channels
with mobile gravel beds. Journal of Hydraulic
Engineering 112(8): 671-689.
Hey, R.D. 1997. Personal communication.
Higginson, N.N.J., and H.T. Johnston. 1989. Riffle-
pool formations in northern Ireland rivers. In
Proceedings of the International Conference on
Channel Flow and Catchment Runoff, pp.
638-647.
Hilsenhoff, W.L. 1982. Using a biotic index to
evaluate water quality in streams. Department
of Natural Resources, Madison, Wisconsin.
Hoag, J.C. 1992. Planting techniques from the
Aberdeen, ID, plant materials center for
vegetating shorelines and riparian areas. In
Symposium on ecology and management of
riparian shrub communities, pp. 165-166.
USDA Forest Service General Technical Report
INT-289.
References
B-11
-------
Hocutt, C.H. 1981. Fish as indicators of biological
integrity. Fisheries 6(6): 28-31.
Hoffman, C.H., and B.D. Winter. 1996. Restoring
aquatic environments: a case study of the Elwha
River. In National parks and protected areas:
their role in environmental protection, ed. R.G.
Wright, pp. 303- 323. Blackwell Science,
Cambridge.
Hollis, F. 1975. The effects of urbanization on
floods of different recurrence intervals. Water
Resources Research 11: 431-435.
Holly, M.F. Jr., J.C. Yang, P. Schwarz, J. Schaefer,
S.H. Su, and R. Einhelling. 1990. CHARIMA -
Numerical simulation of unsteady water and
sediment movement in multiply connected
network of mobile-bed channels. IIHR Report
No. 343. Iowa Institute of Hydraulic Research,
The University of Iowa, Iowa City.
Holmes, N. 1991. Post-project appraisal of
conservation enhancements of flood defense
works. Research and Development Report 2857
1/A. National Rivers Authority, Reading, U.K.
Hoover, R.L., and D.L. Wills, eds. 1984. Managing
forested lands for wildlife. Colorado Division of
Wildlife, Denver.
Horton, R.E. 1933. The role of infiltration in the
hydrologic cycle. EOS, American Geophysical
Union Transactions 14: 446-460.
Horton, R.E. 1945. Erosional development of
streams and their drainage basins: hydrophysical
approach to quantitative morphology. Geologi-
cal Society of America Bulletin 56: 275-370.
Horwitz, R.J. 1978. Temporal variability patterns
and the distributional patterns of stream fishes.
Ecology Monographs 48: 301 -321.
Horwitz, A.J., Demas, C.R. Fitzgerald, K.K. Miller,
T.L., and Rickert, D.A. 1994. U.S. Geological
Survey protocol for the collection and process-
ing of surface-water samples for the subsequent
determination of inorganic constituents in
filtered water. U.S. Geological Survey Open-File
Report 94-539.
Howard, A.D. 1967. Drainage analysis in geologic
interpretation: a summation. Bulletin of the
American Association of Petroleum Geologists
51:2246-59.
Hunt, G.T. 1993. Concerns over air pollution
prompt more controls on construction. Engineer-
ing News-Record, pp. E-57 to E-58.
Hunt, W.A., and R.O. Graham. 1975. Evaluation of
channel changes for fish habitat. ASCE National
Convention meeting reprint (2535).
Hunter, C.J. 1991. Better trout habitat: a guide to
stream restoration and management. Island
Press. November. ISBN: 0933280777.
Huryn, A.D., and J.B. Wallace. 1987. Local geomor-
phology as a determinant of macrofaunal
production in a mountain stream. Ecology 68:
1932-1942.
Hutchison, N.E. 1975. WATSTORE User's Guide -
National Water Data Storage and Retrieval
System, vol. 1. U.S. Geological Survey Open-File
Report 75-426. U.S. Geological Survey.
Hynes, H.B.N. 1970. The ecology of running
waters. University of Liverpool Press, Liverpool,
England.
Ikeda, S., and N. Izumi. 1990. Width and depth of
self-formed straight gravel rivers with bank
vegetation. Water Resources Research 26(10):
2353-2364.
Ikeda, S., G. Parker, and Y. Kimura. 1988. Stable
width and depth of straight gravel rivers with
heterogeneous bed materials. Water Resources
Research 24(5): 713-722.
Inglis, C.C. 1949. The behavior and control of
rivers and canals. U.S. Army Corps of Engineers,
Waterways Experiment Station, Vicksburg,
Mississippi.
Interagency Advisory Committee on Water Data
(IACWD), Hydrology Subcommittee. 1982.
Guidelines for determining flood flow frequency.
Bulletin 17B of the Hydrology Subcommittee,
Office of Water Data Coordination, U.S.
Geological Survey, Reston, Virginia.
B-12
Stream Corridor
-------
Interagency Ecosystem Management Task Force.
1995. The ecosystem approach: healthy
ecosystems and sustainable economies, vol. I,
Overview. Council on Environmental Quality,
Washington, DC.
Iversen, T.M., B. Kronvang, B.L. Madsen, P.
Markmann, and M.B. Nielsen. 1993. Re-
establishment of Danish streams: restoration
and maintenance measures. Aquatic Conserva-
tion: Marine and Freshwater Ecosystems 3:
73-92.
Jackson, W.L., and B.P. Van Haveren. 1984. Design
for a stable channel in coarse alluvium for
riparian zone restoration. Water Resources
Bulletin, American Water Resources Association
20(5): 695-703.
Jacoby, P.W. 1987. Chemical control. Vegetative
Rehabilitation and Equipment Workshop, 41st
Annual Report. U.S. Forest Service, Boise, Idaho.
Jacoby, P.W. 1989. A glossary of terms used in
range management. 3d ed. Society for Range
Management, Denver, Colorado.
Jager, H.I., D.L. DeAngelis, M.J. Sale, W. Van
Winkle, D.D. Schmoyer, M.J. Sabo, D.J. Orth,
and J.A. Lukas. 1993. An individual-based
model for smallmouth bass reproduction and
young-of-year dynamics in streams. Rivers 4:
91-113.
Jansen, P., L. Van Bendegom, J. Van den Berg, M.
De Vries, and A. Zanen. 1979. Principles of
river engineering. Pitman Publishers Inc.,
Belmont, California.
Java, B.J., and R.L. Everett. 1992. Rooting
hardwood cuttings of Sitka and thinleaf alder.
Pages 138-141 in Symposium on ecology and
management of riparian shrub communities.
USDA Forest Service General Technical Report
INT-289. U.S. Department of Agriculture, Forest
Service.
Jennings, M.E., W.O. Thomas, Jr., and H.C. Riggs.
1994. Nationwide summary of U.S. Geological
Survey regional regression equations for
estimating magnitude and frequency of floods
for ungaged sites 1993. U.S. Geological Survey
Water-Resources Investigations Report 94-4002.
U.S. Geological Survey.
Jensen, M.E., R.D. Burmand, and R.G. Allen, eds.
1990. Evapotranspiration and irrigation water
requirements. American Society of Civil
Engineers.
Johannesson, H., and G. Parker. 1985. Computer
simulated migration of meandering rivers in
Minnesota. Project Report No. 242. St.
Anthony Falls Hydraulic Laboratory, University of
Minnesota.
Johnson, A.W., and J.M. Stypula, eds. 1993.
Guidelines for bank stabilization projects in
riverine environments of King County. King
County Department of Public Works, Surface
Water Management Division, Seattle,
Washington.
Johnson, C.D. Ziebell, D.R. Patton, P.F. Ffolliott, and
R.H. Hamre, tech. coords. 1977. Riparian
ecosystems and their management: reconciling
conflicting uses. General Technical Report RM-
120. U.S. Forest Service, Rocky Mountain Forest
and Range Experiment Station, Fort Collins,
Colorado.
Johnson, R.R. 1971. Tree removal along south-
western rivers and effects on associated
organisms. Amer. Phil. Soc. Yearbook 1970:
321-322.
Johnson, R.R., and S.W. Carothers. 1982. Riparian
habitats and recreation: Interrelationships and
impacts in the southwest and rocky mountain
region. USDA Forest Service, Rocky Mountain
Forest and Range Experiment Station,
Eisenhower Consortium, Bulletin 12.
Johnson, R.R., and C.H. Lowe. 1985. On the
development of riparian ecology. In Riparian
ecosystems and their management: Reconciling
conflicting uses, tech coords. R.R. Johnson et al.,
pp. 112-116. USDA Forest Service General
Technical Report RM-120. Rocky Mountain
Forestry and Range Experimental Station, Fort
Collins, Colorado.
Johnson, R.R., and J.M. Simpson. 1971. Important
birds from Blue Point Cottonwoods, Maricopa
County, Arizona. Condor 73: 379-380.
Johnson, W.C. 1994. Woodland expansion in the
Platte River, Nebraska: patterns and causes.
Ecological Monographs 64: 45-84.
References
B-13
-------
Junk, W.J., RB. Bayley, and R.E. Sparks. 1989. The
floodpulse concept in river-floodplain systems.
In Proceedings of the International Large River
Symposium, ed. D.P. Dodge, pp. 110-127. Can.
Spec. Publ. Fish. Aquat. Sci. 106.
Kalmbach, E.R., W.L. McAtee, F.R. Courtsal, and
R.E. Ivers. 1969. Home for birds. U.S. Depart-
ment of the Interior, Fish and Wildlife Service,
Conservation Bulletin 14.
Karle, K.F., and R.V. Densmore. 1994. Stream and
riparian floodplain restoration in a riparian
ecosystem disturbed by placer mining. Ecologi-
cal Engin eering 3: 121-133.
Karr, J.R. 1981. Assessment of biotic integrity
using fish communities. Fisheries 6(6): 21-27.
Karr, J.R., and W. Chu. 1997. Biological monitoring
and assessment: using multimetric indexes
effectively. EPA 235-R97-001. University of
Washington, Seattle.
Karr, J.R., K.D. Fausch, P.L. Angermeier, P.R. Yant,
and I.J. Schlosser. 1986. Assessing biological
integrity in running waters: a method and its
rationale. Illinois Natural History Survey Special
Publication No. 5.
Kasvinsky, J.R. 1968. Evaluation of erosion control
measures on the Lower Winooski River, Vermont.
Master's thesis, Graduate College, University of
Vermont, Burlington, Vermont.
Kauffman, J.B., R.L. Beschta, and W.S. Platts. 1993.
Fish habitat improvement projects in the
Fifteenmile Creek and Trout Creek basins of
Central Oregon: field review and management
recommendations. U.S. Department of Energy,
Bonneville Power Administration, Portland,
Oregon.
Kauffman, J.B., and W.D. Krueger. 1984. Livestock
impacts on riparian ecosystems and streamside
management implications: a review. Journal of
Range Management 37: 430-438.
Keller, E.A. 1978. Pools, riffles, and channelization.
Environmental Geology 2(2): 119-127.
Keller, E.A., and W.N. Melhorn. 1978. Rhythmic
spacing and origin of pools and riffles. Geologi-
cal Society of America Bulletin (89): 723-730.
Kentula, M.E., R.E. Brooks, S.E. Gwin, C.C. Holland,
A.D. Sherman, and J.C. Sinfeos. 1992. An
approach to improving decision making in
wetland restoration and creation. Island Press,
Washington, DC.
Kerchner, J.L. 1997. Setting riparian/aquatic
restoration objectives within a watershed
context. Restoration Ecology 5(45).
Kern, K. 1992. Restoration of lowland rivers: the
German experience. In Lowland floodplain
rivers: geomorphological perspectives, ed. P.A.
Carling and G.E. Petts, pp. 279-297. John Wiley
and Sons, Ltd., Chichester, U.K.
King, R. 1987. Designing plans for constructibility.
Journal of Construction and Management
113:1-5.
Klemm, D. J., P.A. Lewis, F. Fulk, and J. M.
Lazorchak. 1990. Macroinvertebrate field and
laboratory methods for evaluating the biological
integrity of surface waters. EPA/600/4-90-030.
Environmental Monitoring Systems Laboratory,
Cincinnati, Ohio.
Klimas, C.V. 1987. River regulation effects on
floodplain hydrology and ecology. Chapter IV in
The ecology and management of wetlands, ed.
D. Hook et al. Croom Helm, London.
Klimas, C.V. 1991. Limitations on ecosystem
function in the forested corridor along the lower
Mississippi River. In Proceedings of the Interna-
tional Symposium on Wetlands and River
Corridor Management, Association of State
Wetland Managers, Berne, New York,
pp. 61-66.
Knighton, David. 1984. Fluvial forms and process.
Edward Arnold, London.
Knopf, F.L. 1986. Changing landscapes and the
cosmopolitanism of the eastern Colorado
avifauna. Wildlife Society Bulletin 14: 132-142.
B-14
Stream Corridor
-------
Knopf, F.L., and R.W. Cannon. 1982. Structural
resilience of a willow riparian community to
changes in grazing practices. In Proceedings of
Wildlife-Livestock Relationships Symposium, pp.
198-210. University of Idaho Forest, Wildlife
and Range Experiment Station, Moscow, Idaho.
Knopf, F.L., R.R. Johnson, T. Rich, F.B. Samson, a*nd
R.C. Szaro. 1988. Conservation of riparian
systems in the United States. Wilson Bulletin
100: 272-284.
Knott, J.M., G.D. Glysson, B.A. Malo, and LJ.
Schroder. 1993. Quality assurance plan for the
collection and processing of sediment data by
the U.S. Geological Survey, Water Resources
Division. U.S. Geological Survey Open-File
Report 92-499. U.S. Geological Survey.
Knott, J.M., C.J. Sholar, and W.J. Matthes. 1992.
Quality assurance guidelines for the analysis of
sediment concentration by the U.S. Geological
Survey sediment laboratories. U.S. Geological
Survey Open-File Report 92-33. U.S. Geological
Survey.
Kohler, C.C., and W.A. Hubert. 1993. Inland
Fisheries Management in North America.
American Fisheries Society, Bethesda. Maryland.
Kohler, M.A., T.J. Nordenson, and D.R. Baker.
1959. Evaporation maps for the United States.
U.S. Weather Bureau Technical Paper 37.
Kondolf, G.M. 1995. Five elements for effective
evaluation of stream restoration. Restoration
Ecology 3(2): 133-136.
Kondolf, G.M., and E.R. Micheli. 1995. Evaluating
stream restoration projects. Environmental
Management 19(1): 1-15.
Krebs, C.J. 1978. Ecology: the experimental
analysis of distribution and abundance, 2d ed.
Harper and Row, New York.
Lamb, B.L. 1984. Negotiating a FERC license for
the Terror River Project. Water for Resource
Development, Proceedings of the Conference,
American Society of Civil Engineeers, August 14-
17, 1984, ed. D.L Schreiber, pp. 729-734.
Lamberti, G.A., and V.H. Resh. 1983. Stream
periphyton and insect herbivores: an experimen-
tal study of grazing by a caddisfly population.
£co/ogy64: 1124-1135.
Landin, M.C. 1995. The role of technology and
engineering in wetland restoration and creation.
In Proceedings of the National Wetland Engi-
neering Workshop, August 1993, ed. J.C.
Fischenich et al. Technical Report WRP-RE-8.
U.S. Army Engineer Waterways Experiment
Station, Vicksburg, Mississippi.
Landres, P.B., J. Verner, and J.W. Thomas. 1988.
Ecological uses of vertebrate indicator species: a
critique. Conservation Biology 2: 316-328.
Lane, E.W. 1955. The importance of fluvial
morphology in hydraulic engineering. Proceed-
ings of the American Society of Civil Engineers
81(745): 1-17.
Laursen, E.L. 1958. The total sediment load of
streams. Journal of the Hydraulics Division, ASCE
84(HY1 Proc. Paper 1530): 1-36.
Leclerc, M., A. Boudreault, J.A. Bechara, and G.
Corfa. 1995. Two-dimensional hydrodynamic
modeling: a neglected tool in the Instream Flow
Incremental Methodology. Transactions of the
America Fisheries Society. 124: 645-662.
Lee, L.C., and T.M. Hinckley. 1982. Impact of
water level changes on woody riparian and
wetland communities, vol. IX. FWS/OBS-82/22.
Fish and Wildlife Service.
Lee, L.C., T.A. Muir, and R.R. Johnson. 1989.
Riparian ecosystems as essential habitat for
raptors in the American West. In Proceedings of
the Western Raptor Management Symposium
and Workshop, ed. B.G. Pendleton, pp. 15-26.
Institute for Wildlife Research, National Wildlife
Federation. Sci. and Tech. Ser. No. 12.
Leonard, P.M., and D.J. Orth. 1986. Application
and testing of an Index of Biotic Integrity in
small, coolwater streams. Transactions of the
American Fisheries Society 115: 401 -14.
Leopold, A. 1933. The conservation ethic. Journal
of Forestry 31.
References
B-15
-------
Leopold, A. 1953. Round river. From the journals
of Aldo Leopold, ed. Luna Leopold. Oxford
University Press, New York.
Leopold, L.B., 1994. A view of the river. Harvard
University Press, Cambridge, Massachusetts.
Leopold, L.B., and I Maddock, Jr. 1953. The
hydraulic geometry of stream channels and
some physiographic implications. Geological
Survey Professional Paper 252. U.S. Geological
Survey, Washington, DC.
Leopold, L.B., HI. Silvey, and D.L Rosgen. 1997.
The reference reach field book. Wildland
Hydrology, Pagosa Springs, Colorado.
Leopold, L.B., M.G. Wolman, and J.P. Miller. 1964.
Fluvial processes in geomorphology. W. H.
Freeman and Company, San Francisco.
Liebrand, C.I., and K.V. Sykora. 1992. Restoration
of the vegetation of river embankments after
reconstruction. Aspects of Applied Biology 29:
249-256.
Livingstone, A.C., and C.F. Rabeni. 1991. Food-
habit relations that determine the success of
young-of-year smallmouth bass in Ozark
streams. In Proceedings of the First International
Symposium on Smallmouth Bass, ed. D.C.
Jackson. Mississippi Agriculture and Forest
Experiment Station, Mississippi State University.
Lodge, D.M. 1991. Herbivory on freshwater
macrophytes. Aquatic Botany 41: 195-224.
Loeb, S.L., and A. Spacie. 1994. Biological
monitoring of aquatic systems. Papers pre-
sented at a symposium held Nov. 29- Dec. 1,
1990, at Purdue University. Lewis Publishers,
Boca Raton, Florida.
Lohnes, R.A., and R.L. Handy. 1968. Slope angles
in friable loess. Journal of Geology 76(3):
247-258.
Lohoefener, R.R. 1997. Personal communication.
Deputy Chief, Division of Endangered Species,
U.S. Fish and Wildlife Service, Arlington, VA.
Lowe, C.H., ed. 1964. The vertebrates of Arizona.
University of Arizona Press, Tucson, Arizona.
Lowe, C.H., and F.A. Shannon. 1954. A new lizard
(genus Eumeces) from Arizona. Herpetologica
10: 185-187.
Lowrance, R.R., R.L. Todd, and L.E. Asmussen.
1984b. Nutrient cycling in an agricultural
watershed: I. Phreatic movement. Journal of
Environmental Quality 13: 22-27.
Lowrance, R.R., R. Todd, J. Fail, Jr., 0. Hendrickson,
Jr., R. Leonard, and L. Asmussen. 1984a.
Riparian forests as nutrient filters in agricultural
watersheds. BioScience 34: 374-377.
Lumb, A.M., J.L. Kittle, Jr., and K.M. Flynn. 1990.
Users manual for ANNIE, a computer program
for interactive hydrologic analyses and data
management. U.S. Geological Survey Water-
Resources Investigations Report 89-4080. U.S.
Geological Survey, Reston, Virginia.
Luttenegger, J.A., and B.R. Hallberg. 1981.
Borehole shear test in geotechnical investiga-
tions. American Society of Testing Materials
Special Publication No. 740.
Lutton, R.J. 1974. Use of loess soil for modeling
rock mechanics. Report S-74-28. U.S. Army
Corps of Engineers, Waterways Experiment
Station, Vicksburg, Mississippi.
Lynch, J.A., E.S. Corbett, and W.E. Sopper. 1980.
Evaluation of management practices on the
biological and chemical characteristics of
streamflow from forested watersheds. Technical
Completion Report A-041 -PA. Institute for
Research on Land and Water Resources, The
Pennsylvania State University, State College.
Lyons, J., L. Wang, and T.D. Simonson. 1996.
Development and validation of an index of biotic
integrity for coldwater streams in Wisconsin.
North American Journal of Fisheries Manage-
ment 16: 241-56.
MacArthur, R.H., and J.W. MacArthur. 1961. On
bird species diversity. Ecology 42: 594-598.
MacBroom, J.G. 1981. Open channel design
based on fluvial geomorphology. In Water
Forum '81, American Society of Civil Engineers,
New York, pp. 844-851.
B-16
Stream Corridor
-------
MacDonald, L.H., A.W. Smart, and R.C. Wissmar.
1991. Monitoring guidelines to evaluate the
effect of forestry activities in streams in the
Pacific Northwest. EPA/910/9-91-001. USEPA
Region 10, Seattle, Washington.
Mackenthun, K.M. 1969. The practice of water
pollution biology. U.S. Department of the
Interior, Federal Water Pollution Control
Administration, Division of Technical Support.
U.S. Government Printing Office, Washington,
DC.
Macrae, C. 1996. Experience from morphological
research on Canadian streams: Is control of the
two-year frequency runoff event the best basis
for stream channel protection? In Effects of
Foundation Conference Proceedings, Snowbird,
Utah, August 4-9, 1996, pp. 144-160.
Madej, M.A. 1982. Sediment transport and
channel changes in an aggrading stream in the
Puget Lowland, Washington. U.S. Forest Service
General Technical Report PNW-141. U.S.
Department of Agriculture, Forest Service.
Magnuson, J.J., L.B. Crowder, and RA. Medvick.
1979. Temperature as an ecological resource.
American Zoology 19: 331-343.
Magurran, A.E. 1988. Ecological diversity and its
measurement. Princeton University Press,
Princeton, New Jersey.
Malanson, G.P. 1993. Riparian landscapes.
Cambridge University Press, Cambridge.
Manley, P.A., et al. 1995. Sustaining ecosystems: a
conceptual framework. USDA Forest Service,
Pacific Southwest Region, San Francisco,
California.
Mann, C.C., and Ml. Plummer. 1995. Are wildlife
corridors the right path? Science 270:
1428-1430.
Mannan, R.W., Ml. Morrison, and E.C. Meslow.
1984. The use of guilds in forest bird manage-
ment. Wildlife Society Bulletin 12: 426-430.
Maret, T.J. 1985. The effect of beaver ponds in
the water quality of Currant Creek, Wyoming.
M.S. thesis, University of Wyoming, Laramie.
Marion, J.L., and L.C. Merriam. 1985. Predictability
of recreational impact on soils. Soil Science
Society of America Journal 49: 7 51 -7 53.
Martin, C.O., ed. 1986. U.S. Army Corps of
Engineers wildlife resources management
manual (serial technical reports dated 1986-
1995). U.S. Army Engineer Waterways Experi-
ment Station, Vicksburg, Mississippi.
Maser, C., and J.R. Sedell. 1994. From the forest
to the sea: the ecology of wood in streams,
rivers, estuaries, and oceans. St. Lucie Press,
Delray Beach, Florida.
Matthews W.J., and J.T. Styron. 1980. Tolerance of
headwater vs. mainstream fishes for abrupt
physicochemical changes. American Midland
Naturalist 105 149-158.
May, C., R. Horner, J. Karr, B. Mar, and E. Welch.
1997. Effects of urbanization on small streams
in the Puget Sound ecoregion. Watershed
Protection Technique 2(4): 483-494.
McAnally, W.H., and W.A. Thomas. 1985. User's
manual for the generalized computer program
system, open-channel flow and sedimentation,
TABS-2, main text. U.S. Army Corps of Engi-
neers, Waterways Experiment Station, Hydraulics
Lab, Vicksburg, Mississippi.
McClendon, D.D., and C.F. Rabeni. 1987. Physical
and biological variables useful for predicting
population characteristics of smallmouth bass
and rock bass in an Ozark stream. North Am. J.
Fish. Manag. 7: 46-56.
McDonald, L.H., et al. 1991. Monitoring guidelines
to evaluate effects of forestry activities on
streams in the Pacific Northwest and Alaska.
U.S. Environmental Protection Agency, Region
10, Seattle, Washington.
McGinnies, W.J. 1984. Seeding and planting. In
Vegetative rehabilitation and equipment
workshop, 38th Annual Report, pp. 23-25. U.S.
Forest Service, Rapid City, South Dakota.
McKeown, B.A. 1984. Fish migration. Timber
Press, Beaverton, Oregon.
References
B-17
-------
Mclaughlin Water Engineers, Ltd. 1986. Evaluation
of and design recommendations for drop
structures in the Denver Metropolitan Area. A
report prepared for the Denver Urban Drainage
and Flood Control District by Mclaughlin Water
Engineers, Ltd.
Medin, D.E., and W.P. Clary. 1990. Bird popula-
tions in and adjacent to a beaver pond ecosys-
tem and adjacent riparian habitat in Idaho.
USDA Forest Service, Intermountain Forest and
Range Experiment Station, Ogden, Utah.
Meffe, G.K., C.R. Carroll, and contributors. 1994.
Principles of conservation biology. Sinauer
Associates, Inc., Sunderland, Massachusetts.
Metropolitan Washington Council of Governments
(MWCOG). 1997. An existing source assess-
ment of pollutants to the Anacostis watershed,
ed. A. Warner, D. Shepp, K. Corish, and J. Galli.
Washington, DC.
Meyer-Peter, E., and R. Muller. 1948. Formulas for
bed-load transport. In International Association
for Hydraulic Structures Research, 2nd Meeting,
Stockholm, Sweden, pp. 39-64.
Milhous, R.T., J.M. Bartholow, M.A. Updike, and
A.R. Moos. 1990. Reference manual for
generation and analysis of habitat time series
Version II. U.S. Fish and Wildlife Service
Biological Report 90(16). U.S. Fish and Wildlife
Service.
Milhous, R.T., M.A. Updike, and D.M. Schneider.
1989. Physical Habitat Simulation System
Reference ManualVersion II. Instream Flow
Information Paper No. 26. U.S. Fish and Wildlife
Service Biological Report 89(16). U.S. Fish and
Wildlife Service.
Miller, J.E. 1983. Beavers. In Prevention and
control of wildlife damage, ed. R.M. Timm, pp.
B1-B11. Great Plains Agricultural Council and
Nebraska Cooperative Extension Service,
University of Nebraska, Lincoln.
Miller, G.T. 1990. Living in the environment: an
introduction to environmental science. 6th ed.
Wadsworth Publishing Company, Belmont,
California.
Miller, A.C., R.H. King, and J.E. Glover. 1983.
Design of a gravel bar habitat for the Tombigbee
River near Columbus, Mississippi. Miscellaneous
Paper EL-83-1. U.S. Army Corps of Engineers,
Waterways Experiment Station, Environmental
Laboratory, Vicksburg, Mississippi.
Mills, W.B., D.B. Porcella, M.J. Ungs, S.B. Gherini,
K.V. Summers, L. Mok, G.L. Rupp, G.L. Bowie
and D.A. Haith. 1985. Water quality assess-
ment: a screening procedure for toxic and
conventional pollutants in surface and ground
water. EPA/600/6-85/002a-b. U.S. Environmen-
tal Protection Agency, Office of Research and
Development, Athens, Georgia.
Minckley, W.L., and M.E. Douglas. 1991. Discov-
ery and extinction of western fishes: a blink of
the eye in geologic time. In Battle against
extinction: native fish management in the
American West, ed. W.L. Minckley and J.E.
Deacon, pp. 7-18. University of Arizona Press,
Tucson.
Minshall, G.W. 1978. Autotrophy in stream
ecosystems. BioScience 28: 767-771.
Minshall, G.W. 1984. Aquatic insect-substratum
relationships. In The ecology of aquatic insects,
ed. V.H. Resh and D.M. Rosenberg, pp. 358-400.
Praeger, New York.
Minshall, G.W., K.W. Cummins, R.C. Petersen, C.E.
Cushing, D.A. Bruns, J.R. Sedell, and R.L.
Vannote. 1985. Developments in stream
ecosystem theory. Canadian Journal of Fisheries
and Aquatic Sciences 42: 1045-1055.
Minshall, G.W., R.C. Petersen, K.W. Cummins, T.L.
Bott, J.R. Sedell, C.E. Cushing, and R.L. Vannote.
1983. Interbiome comparison of stream
ecosystem dynamics. Ecological Monographs
53: 1-25.
Molinas, A., and C.T. Yang. 1986. Computer
program user's manual for GSTARS (Generalized
Stream Tube model for Alluvial River Simulation).
U.S. Bureau of Reclamation Engineering and
Research Center, Denver, Colorado.
Montana Department of Environmental Quality
(MDEQ). 1996. Montana Streams Management
Guide, ed. C. Duckworth and C. Massman.
B-18
Stream Corridor
-------
Montgomery, D.R., and J.M.Buffington, 1993.
Channel classification, prediction of channel
response and assessment of channel condition.
Report TFW-SH10-93-002. Department of
Geological Sciences and Quaternary Research
Center, University of Washington, Seattle.
Moore, J.S., D.M. Temple, and H.A.D. Kirsten.
1994. Headcut advance threshold in earth
spillways. Bulletin of the Association of Engi-
neering Geologists 31(2): 277-280.
Morin, A., and D. Nadon. 1991. Size distribution
of epilithic lotic invertebrates and implications
for community metabolism. Journal of the North
American Benthological Society 10: 300-308.
Morris, L.A., A.V. Mollitor, K.J. Johnson, and A.L
Leaf. 1978. Forest management of floodplain
sites in the northeastern United States. In
Strategies for protection and management of
floodp/ain wetlands and other riparian ecosys-
tems, ed. R.R. Johnson, and J.F. McCormick, pp.
236-242. USDA Forest Service General Technical
Report WO-12. U.S. Department of Agriculture,
Forest Service.
Moss, B. 1988. Ecology of fresh waters: man and
medium. Blackwell Scientific Publication,
Boston.
Myers, W.R., and J.F. Lyness. 1994. Hydraulic
study of a two-stage river channel. Regulated
Rivers: Research and Management 9(4):
225-236.
Naiman, R.J., T.J. Beechie, I.E. Benda, D.R. Berg,
P.A. Bisson, L.H. MacDonald, M.D. O'Connor,
P.L Olson, and E.A. Steel. 1994. Fundamental
elements of ecologically healthy watersheds in
the Pacific northwest coastal ecoregion. In
Watershed management, ed. R. Naiman, pp.
127-188. Springer-Verlag, New York.
Naiman, R.J., J.M. Melillo, and J. E. Hobbie. 1986.
Ecosystem alteration of boreal forest streams by
streams by beaver (Castor canadensis). Ecology
67(5): 1254-1269.
Nanson, G.C., and E.J. Hickin. 1983. Channel
migration and incision on the Beatton River.
Journal of Hydraulic Engineering 109(3):
327-337.
National Academy of Sciences. 1995. Wetlands:
characteristics and boundaries. National
Academy Press, Washington, DC.
National Park Service (NPS). 1995. Final environ-
mental impact statement, Elwha River ecosystem
restoration. U.S. Department of the Interior,
National Park Service, Olympic National Park,
Port Angeles, Washington.
National Park Service (NPS). 1996. Final environ-
mental impact statement, Elwha River ecosystem
restoration implementation. U.S. Department of
the Interior, National Park Service, Olympic
National Park, Port Angeles, Washington.
National Research Council (NRC). 1983. An
evaluation of flood-level prediction using alluvial
river models. National Academy Press,
Washington, DC.
National Research Council (NRC). 1992. Restora-
tion of aquatic ecosystems: science, technology,
and public policy. National Academy Press,
Washington, DC.
Needham, P.R. 1969. Trout streams: conditions
that determine their productivity and sugges-
tions for stream and lake management. Revised
by C.F. Bond. Holden-Day, San Francisco.
Nehlsen, W., J.E. Williams, & J.A. Lichatowich.
1991. Pacific salmon at the crossroads: stocks
at risk from California, Oregon, Idaho, and
Washington. Fisheries (Bethesda) 16(2): 4-21.
Nehring, R.B., and R.M. Anderson. 1993. Determi-
nation of population-limiting critical salmonid
habitats in Colorado streams using the Physical
Habitat Simulation System. Rivers 4C\): 1-19.
Neill, W.M. 1990. Control of tamarisk by cut-
stump herbicide treatments. In Tamarisk control
in southwestern United States, pp. 91-98.
Cooperative National Park Research Studies
Unit, Special Report Number 9. School of
Renewable Natural Resources, University of
Arizona, Tucson.
Neilson, P.M., IN. Waller, and K.M. Kennedy. 1991.
Annotated bibliography on grade control
structures. Miscellaneous Paper HL-91-4. U.S.
Army Corps of Engineers, Waterways Experiment
Station, CE, Vicksburg, Mississippi.
References
B-19
-------
Nelson, J.M, and J.D. Smith. 1989. Evolution and
stability of erodible channel beds. In River
Meandering, ed. S. Ikeda and G. Parker. Water
Resources Monograph 12, American Geophysi-
cal Union, Washington, DC.
Nestler, J.M., R.T. Milhouse, and J.B. Layzer. 1989.
Instream habitat modeling techniques. Chapter
12 in Alternatives in regulated river manage-
ment, ed. J.A. Gore and G.E. Petts, Chapter 12.
CRC Press, Inc., Boca Raton, Florida.
Nestler, J., T. Schneider, and D. Latka. 1993.
RCHARC: A new method for physical habitat
analysis. Engineering Hydrology :294-99.
Newbury, R.W., and M.N. Gaboury. 1993. Stream
analysis and fish habitat design: a field manual.
Newbury Hydraulics Ltd., Gibsons, British
Columbia.
Nixon, M. 1959. A Study of bankfull discharges of
rivers in England and Wales. In Proceedings of
the Institution of Civil Engineers, vol. 12, pp.
157-175.
Noss, R.F. 1983. A regional landscape approach to
maintain diversity. BioScience 33: 700-706.
Noss, R.F. 1987. Corridors in real landscapes: a
reply to Simberloff and Cox. Conservation
Biology 1: 159-164.
Noss, R.F. 1991. Wilderness recovery: thinking big
in restoration ecology. Environmental Profes-
sional } 3(3): 225-234. Corvallis, Oregon.
Noss, R.F. 1994. Hierarchical indicators for
monitoring changes in biodiversity. In Principles
of conservation biology, G.K. Meffe, C.R.
Carroll, et al., pp. 79-80. Sinauer Associates,
Inc., Sunderland, Massachusetts.
Noss, R.F., and L.D. Harris. 1986. Nodes, net-
works, and MUMs: preserving diversity at all
scales. Environmental Management 10(3):
299-309.
Novotny and Olem. 1994. Water quality, preven-
tion, identification, and management of diffuse
pollution. Van Nostrand Reinhold, New York.
Nunnally, N.R., and F.D. Shields. 1985. Incorpora-
tion of environmental features in flood control
channel projects. Technical Report E-85-3. U.S.
Army Corps of Engineers, Waterways Experi-
ment Station, Vicksburg, MS.
Odgaard, J. 1987. Streambank erosion along two
rivers in Iowa. Water Resources Research 23(7):
1225-1236.
Odgaard, J. 1989. River-meander model I:
development. Journal of Hydraulic Engineering
115(11): 1433-1450.
Odum, E.P. 1959. Fundamentals of ecology.
Saunders, Philadelphia.
Odum, E.P. 1971. Fundamentals of ecology, 3d
ed. W.B. Saunders Company, Philadelphia, PA.
574 pp.
Odum, E.P. 1989. Ecology and our endangered
life-support systems. Sinauer Associates, Inc.,
Sunderland, Massachusetts.
Ohio EPA. 1990. Use of biocriteria in the Ohio EPA
surface water monitoring and assessment
program. Ohio Environmental Protection
Agency, Division of Water Quality Planning and
Assessment, Columbus, Ohio.
Ohmart, R.D., and B.W. Anderson. 1986. Riparian
habitat. In Inventory and monitoring of wildlife
habitat, ed. A.Y. Cooperrider, R.J. Boyd, and
H.R. Stuart, pp. 169-201. U.S. Department of
the Interior, Bureau of Land Management
Service Center, Denver, Colorado.
Olive, S.W., and B.L. Lamb. 1984. Conducting a
FERC environmental assessment: a case study
and recommendations from the Terror Lake
Project. FWS/OBS-84/08. U.S. Fish and Wildlife
Service.
Oliver, C.D., and T.M. Hinckley. 1987. Species,
stand structures and silvicultural manipulation
patterns for the streamside zone. In Streamside
management: forestry and fishery interactions,
ed. E.O. Salo and T.W. Cundy, pp. 259-276.
Institute of Forest Resources, University of
Washington, Seattle.
B-20
Stream Corridor
-------
Olson, R., and W.A. Hubert. 1994. Beaver: Water
resources and riparian habitat manager.
University of Wyoming, Laramie.
Olson, IE., and F.L. Knopf. 1986. Agency subsidi-
zation of a rapidly spreading exotic. Wildlife
Society Bulletin 14: 492-493.
Omernik, J.M. 1987. Ecoregions of the cotermi-
nous United States. Ann. Assoc. Am. Geol.
77(1): 118- 125.
Orsborn, J.F., Jr., R.T. Cullen, B.A. Heiner, C.M.
Garric, and M. Rashid. 1992. A handbook for
the planning and analysis of fisheries habitat
modification projects. Department of Civil and
Environmental Engineering, Washington State
University, Pullman.
Orth, D.J., and R.J. White. 1993. Stream habitat
management. Chapter 9 in Inland fisheries
management in North America, ed. C.C. Kohler
and W.A. Hubert. American Fisheries Society,
Bethesda, Maryland.
Osman, A.M., and C.R. Thorne. 1988. Riverbank
stability analysis; I: Theory. Journal of Hydraulic
Engineering, ASCE 114(2): 134-150.
Pacific Rivers Council. 1996. A guide to the
restoration of watersheds and native fish in the
pacific northwest, Workbook II, Healing the
Watershed series.
Parker, G. 1978. Self-formed straight rivers with
equilibrium banks and mobile bed, 2, the gravel
river. Journal of Fluid Mechanics 9(1): 127-146.
Parker, G. 1982. Discussion of Chapter 19:
Regime equations for gravel-bed rivers. In
Gravel-bed rivers: fluvial processes, engineering
and management, ed. R.D. Hey, J.C. Bathurst,
and C.R. Thorne, pp. 542-552. John Wiley and
Sons, Chichester, U.K.
Parker, G. 1990. Surface bedload transport
relation for gravel rivers. Journal of Hydraulic
Research 28(4): 417-436.
Parker, M. 1986. Beaver, water quality, and
riparian systems. In Wyoming's water doesn't
wait while we debate: proceedings of the
Wyoming water 1986 and streamside zone
conference, pp. 88-94. University of Wyoming,
Laramie.
Parsons, S., and S. Hudson. 1985. Channel cross-
section surveys and data analysis. TR-4341 -1.
U.S. Department of the Interior, Bureau of Land
Management Service Center, Denver, Colorado.
Payne, N.F., and F.C. Bryant. 1994. Techniques for
wildlife habitat management of Uplands, New
York. McGraw-Hill.
Pearlstine, L, H. McKellar, and W. Kitchens. 1985.
Modelling the impacts of a river diversion on
bottomland forest communities in the Santee
River floodplain, South Carolina. Ecological
Modelling 7: 283-302.
Peckarsky, B.L. 1985. Do predaceous stoneflies and
siltation affect the structure of stream insect
communities colonizing enclosures? Canadian
Journal of Zoology 63: 1519-1530.
Petersen, M.S. 1986. River engineering. Prentice-
Hall, Englewood Cliffs, New Jersey.
Pickup, G., and R.F. Warner. 1976. Effects of
hydrologic regime on the magnitude and
frequency of dominant discharge. Journal of
Hydrology 29: 51-75.
Pielou, E.C. 1993. Measuring biodiversity:
quantitative measures of quality. In Our living
legacy: Proceedings of a symposium on biologi-
cal diversity, ed. M.A. Fenger, E.H. Miller, J.A.
Johnson, and E.J.R. Williams, pp. 85-95. Royal
British Columbia Museum, Victoria, British
Columbia.
Plafkin, J.L., M.T. Barbour, K.D. Porter, S.K. Gross,
and R.M. Hughes. 1989. Rapid bioassessment
protocols for use in streams and rivers. EPA444/
4-89-001. U.S. Environmental Protection Agency,
Washington, DC.
Platts, W.S. 1979. Livestock grazing and riparian/
stream ecosystems. In Proceedings of the forum
on Grazing and Riparian/Stream Ecosystems, pp.
39-45. Trout Unlimited, Inc., Vienna, Virginia.
References
B-21
-------
Platts, W.S. 1987. Methods for evaluating riparian
habitats with applications to management.
General Technical Report INT-21. U.S. Depart-
ment of Agriculture, Forest Service, Intermountain
Research Station, Ogden, Utah.
Platts, W.S. 1989. Compatibility of livestock
grazing strategies with fisheries. In Proceedings
of an educational workshop on practical
approaches to riparian resource management,
pp. 103-110. BLM-MT-PT-89-001-4351. U.S.
Department of the Interior, Bureau of Land
Management, Billings, Montana.
Platts, W.S., and Rinne. 1985. Riparian and stream
enhancement management and research in the
Rocky Mountains. North American Journal of
Fishery Management 5: 115-125.
Poff, N., J.D. Allan, M.B. Bain, J.R. Karr, K.L.
Prestegaard, B.D. Richter, R.E. Sparks, and J.C.
Stromberg. 1997. The natural flow regime: a
paradigm for river conservation and restoration.
Bioscience (in press).
Ponce, V.M. 1989. Engineering hydrology:
principles and practices. Prentice-Hall,
Englewood Cliffs, New Jersey.
Prichard et al. 1993. rev. 1995. Process for
assessing proper conditions. Technical Refer-
ence 1737-9. U.S. Department of the Interior,
Bureau of Land Management Service Center,
Denver, Colorado.
Rabeni, C.F., and RB. Jacobson. 1993. The impor-
tance of fluvial hydraulics for fish-habitat
restoration in low-gradient alluvial streams.
Freshwater Biology 29: 211 -220.
Rantz, S.E., et al., 1982. Measurement and
computation of streamflow. USGS Water Supply
Paper 2175, 2 vols. U.S. Geological Survey,
Washington, DC.
Raudkivi, A.J., and S.K. Tan. 1984. Erosion of
cohesive soils. Journal of Hydraulic Research
22(4): 217-233.
Rechard, R.P., and R.G. Schaefer. 1984. Stripmine
streambed restoration using meander param-
eters. In River meandering, Proceedings of the
Conference Rivers '83, ed. C.M. Elliot, pp. 306-
317. American Society of Civil Engineers, New
York.
Reiser, D.W., M.P. Ramey, and T.A. Wesche. 1989.
Flushing flows. In Alternatives in regulated river
management, ed. M.A. Fenger, E.H. Miller, J.A.
Johnson, and E.J.R. Williams, pp. 91-135. CRC
Press, Boca Raton, Florida.
Resh, V.H., A.V. Brown, A.P. Covich, M.E. Gurtz,
H.W. Li, G.W. Minshall, S.R. Reise, A.L. Sheldon,
J.B. Wallace, and R.C. Wissmar. 1988. The role
of disturbance in stream ecology. Journal of the
North American Benthological Society 7:
433-455.
Reynolds, C.S. 1992. Algae. In The rivers hand-
book, vol. 1, ed. P. Calow and G.E. Petts, pp.
195-215. Blackwell Scientific Publications,
Oxford.
Richards, K.S. 1982. Rivers: form and process in
alluvial channels. Methuen, London.
Ricklefs, R.E. 1979. Ecology. 2d ed. Chiron Press,
New York.
Ricklefs, R.E. 1990. Ecology. W.H. Freeman, New
York.
Rieger, J.P., and D.A. Kreager. 1990. Giant reed
(Arundodonax): a climax community of the
riparian zone. In California riparian systems:
protection, management, and restoration for
the 1990's, tech. coord. D.L. Abel, pp. 222-225.
Pac. SW. For. and Range Exper. Stat., Berkeley,
California.
Ries, K.G. III. 1994. Estimation of Low-flow
duration discharges in Massachusetts. U.S.
Geological Survey Water-Supply Paper 2418.
U.S. Geological Survey.
Riggs, H.C., et al., 1980. Characteristics of low
flows. Journal of Hydraulic Engineering, ASCE
106(5): 717-731.
Riley, A.L. 1998. Restoring stream in cities: a guide
for planners, policy-makers, and citizens. Ireland
Press.
B-22
Stream Corridor
-------
Riley, A.L., and M. McDonald. 1995. Urban
waterways restoration training manual for Youth
and Conservation Corps. National Association of
Conservation Corps, Under agreement with the
U.S. Environmental Protection Agency, Office of
Policy, Planning, and Evaluation and the Natural
Resource Conservation Service, Washington, DC.
Ringelman, J.K. 1991. Managing beaver to benefit
waterfowl. Fish and Wildlife Leaflet 13.4.7.
U.S. Fish and Wildlife Service, Washington, DC.
Roberson, J.A., and C.T. Crowe. 1996. Engineer-
ing fluid mechanics, 6th ed. John Wiley and
Sons, New York. October. ISBN: 0471147354.
Rodgers, Jr., J.H., K.L Dickson, and J. Cairns, Jr.
1979. A review and analysis of some methods
used to measure functional aspects of periphy-
ton. In Methods and measurements of periphy-
ton communities: a review, ed. R.I. Weitzel.
Special publication 690. American Society for
Testing and Materials.
Rood, S.B., and J.M. Mahoney. 1990. Collapse of
riparian poplar forests downstream from dams
in western prairies: probable causes and
prospects for mitigation. Environmental
Management 14: 451-464.
Rosgen, D.L. 1996. Applied river morphology.
Wildland Hydrology, Colorado.
Roy, A.G., and A.D. Abrahams. 1980. Discussion
of rhythmic spacing and origin of pools and
riffles. Geological Society of America Bulletin
91: 248-250.
Rudolph, R.R., and C.G. Hunter. 1964. Green trees
and greenheads. In Waterfowl tomorrow, ed.
J.P. Linduska, pp. 611-618. U.S. Department
of the Interior, Fish and Wildlife Service,
Washington, DC.
Ruttner, F. 1963. Fundamentals of limnology.
Transl. D.G. Frey and F.E.J. Fry. University of
Toronto Press, Toronto.
Ryan, J., and H. Short. 1995. The Winooski River
Watershed evaluation project report. USDA-
Natural Resources Conservation Service/
Americorps Program, Williston, Vermont.
Salo, E.O., and T.W. Cundy. 1987. Streamside
management: forestry and fishery interactions.
Contribution No. 57. University of Washington
Institute of Forest Resources, Seattle.
Sanders, T.G., R.C. Ward, J.C. Loftis, T.D. Steele,
D.D. Adrian, and V. Yevjevich. 1983. Design of
networks for monitoring water quality. Water
Resources Publications, Littleton, Colorado.
Sauer, V.B., W.O. Thomas, Jr., V.A. Strieker, and K.V.
Wilson. 1983. Flood characteristics of urban
watersheds in the United States, U.S. Geologi-
cal Survey Water-Supply Paper 2207. U.S.
Geological Survey.
Schamberger, M., A.M. Farmer, and J.W. Terrell.
1982. Habitat Suitability Index models: intro-
duction. FWS/OBS-82/10. U.S Department of
the Interior, U.S. Fish and Wildlife Service,
Washington, DC.
Schopmeyer, C.S., ed. 1974. Seeds of woody
plants in the United States. U.S. Department of
Agriculture Agronomy Handbook 450. U.S.
Department of Agriculture, Forest Service,
Washington, DC.
Schreiber, K. 1995. Acidic deposition ("acid rain").
In Our living resources: a report to the nation
on the distribution, abundance, and health of
U.S. plants, animals, and ecosystems, ed. T.
LaRoe, G.S. Ferris, C.E. Puckett, P.O. Doran, and
MJ. Mac. U.S. Department of the Interior,
National Biological Service, Washington, DC.
Schroeder, R.L., and A.W. Allen. 1992. Assessment
of habitat of wildlife communities on the Snake
River, Jackson, Wyoming. U.S. Department of
the Interior, Fish and Wildlife Service.
Schroeder, R.L., and S.L. Haire. 1993. Guidelines
for the development of community-level habitat
evaluation models. Biological Report 8. U.S.
Department of the Interior, U.S. Fish and Wildlife
Service, Washington, DC.
Schroeder, R.L., and M.E. Keller. 1990. Setting
objectives: a prerequisite of ecosystem manage-
ment. New York State Museum Bulletin 471:1-4.
References
B-23
-------
Schueler, T. 1987. Controlling urban runoff: a
practical manual for planning and designing
urban best management practices. Metropolitan
Washington Council of Governments,
Washington, DC.
Schueler,!. 1995. The importance of impervious-
ness. Watershed Protection Techniques 1 (3):
100-111.
Schueler,! 1996. Controlling cumulative impacts
with sub-watershed plans. In Assessing the
cumulative impacts of watershed development
on aquatic ecosystems and water quality,
proceedings of 1996 symposium.
Schuett-Hames, D., A. Pleus, L. Bullchild, and S.
Hall, eds. 1993. Timber-Fish-Wildlife ambient
monitoring program manual. TFW-AM-93-001.
Northwest Indian Fisheries Commission,
Olympia, Washington.
Schumm, S.A. 1960. The shape of alluvial
channels in relation to sediment type. U.S
Geological Survey Professional Paper 352-B.
U.S. Geological Survey.
Schumm, S.A. 1977. The fluvial system. John
Wiley and Sons, New York.
Schumm, S.A., M.D. Harvey, and C.C. Watson.
1984. Incised channels: morphology, dynamics
and control. Water Resources Publications,
Littleton, Colorado.
Searcy, J.K. 1959. Manual of hydrology; pan 2,
Low-flow techniques. U.S. Geological Survey
Supply Paper W 1542-A.
Sedell J.S., G.H. Reeves, F.R. Hauer, J.A. Stanford,
and C.P. Hawkins. 1990. Role of refugia in
recovery from disturbances: modern fragmented
and disconnected river systems. Environmental
Management 14: 711-724.
Sedgwick, J.A., and F.L. Knopf. 1986. Cavity-
nesting birds and the cavity-tree resource in
plains cottonwood bottomlands. Journal of
Wildlife Management 50: 247-252.
Seehorn, M.E. 1985. Fish habitat improvement
handbook. Technical Publication R8-TP 7. U.S.
Department of Agriculture Forest Service,
Southern Region.
Severson, K.E. 1990. Summary: livestock grazing
as a wildlife habitat management tool. In Can
livestock be used as a tool to enhance wildlife
habitat? tech coord. K.E. Severson, pp. 3-6.
U.S. Department of Agriculture Forest Service,
Rocky Mountain Forest and Range Experiment
Station General Technical Report RM-194.
Shampine, W.J., L.M. Pope, and M.T. Koterba.
1992. Integrating quality assurance in project
work plans of the United States Geological
Survey. United States Geological Survey Open-
File Report 92- 162.
Shaver, E., J. Maxted, G. Curtis and D. Carter.
1995. Watershed protection using an inte-
grated approach. In Proceedings from
Stormwater NPDES-related Monitoring Needs,
ed, B. Urbonas and L. Roesner, pp. 168-178.
Engineering Foundation Conference, Crested
Butte, Colorado, August 7-12, 1994.
Shear, T.H., T.J. Lent, and S. Fraver. 1996. Com-
parison of restored and mature bottomland
hardwood forests of Southwestern Kentucky.
Restoration Ecology 4(2): 111 -123.
Shelton, L.R. 1994. Field guide for collecting and
processing stream-water samples for the
National Water Quality Assessment Program.
U.S. Geological Survey Open-File Report 94-455.
Shelton, L.R., and P.O. Capel. 1994. Field guide for
collecting and processing samples of stream bed
sediment for the analysis of trace elements and
organic contaminants for the National Water
Quality Assessment Program. U.S. Geological
Survey Open-File Report 94-458.
Shields, F.D., Jr. 1983. Design of habitat structures
for open channels. Journal of Water Resources
Planning and Management 109(4): 331-344.
Shields, F.D., Jr. 1987. Management of environ-
mental resources of cutoff bends along the
Tennessee- Tombigbee Waterway. Final report.
Miscellaneous Paper EL-87-12. U.S. Army Corps
of Engineers, Waterways Experiment Station,
Vicksburg, Mississippi.
B-24
Stream Corridor
-------
Shields, F.D., Jr. 1988. Effectiveness of spur dike
notching. Hydraulic engineering: proceedings of
the 1988 national conference, ed. S.R. Abt and
J. Gessler, 334-30.1256. American Society of
Civil Engineers, New York.
Shields, F.D., Jr. 1991. Woody vegetation and
riprap stability along the Sacramento River Mile
84.5-119. Water Resources Bulletin 27:
527-536.
Shields, F.D., Jr., and N.M. Aziz. 1992. Knowledge-
based system for environmental design of stream
modifications. Applied Engineering Agriculture,
ASCE 8(4): 553-562.
Shields, F.D., Jr., A.J. Bowie, and CM. Cooper.
1995. Control of streambank erosion due to
bed degradation with vegetation and structure.
Water Resources Bulletin 31(3): 475-489.
Shields, F.D., Jr., and J.J. Hoover. 1991. Effects of
channel restabilization on habitat diversity,
Twentymile Creek, Mississippi. Regulated Rivers:
Research and Management (6): 163-181.
Shields, F.D., Jr., S.S. Knight, and C.M. Cooper.
1994. Effects of channel incision on base flow
stream habitats and fishes. Environmental
Management 18: 43-57.
Short, HI. 1983. Wildlife guilds in Arizona desert
habitats. U.S. Bureau of Land Management
Technical Note 362. U.S. Department of the
Interior, Bureau of Land Management.
Simberloff, D., and J. Cox. 1987. Consequences
and costs of conservation corridors. Conserva-
tion Biology 1: 63-71.
Simmons, D., and R. Reynolds. 1982. Effects of
urbanization on baseflow of selected south
shore streams, Long Island, NY. Water Re-
sources Bulletin 18(5): 797-805.
Simon, A. 1989a. A model of channel response in
distributed alluvial channels. Earth Surface
Processes and Landforms 14(1): 11-26.
Simon, A. 1989b. The discharge of sediment in
channelized alluvial streams. Water Resources
Bulletin, American Water Resources Association
25(6): 1177-1188. December.
Simon, A. 1992. Energy, time, and channel
evolution in catastrophically disturbed fluvial
systems. In Geomophic systems: geomorphology
ed. J.D. Phillips and W.H. Renwick, vol. 5, pp.
345-372.
Simon, A. 1994. Gradation processes and channel
evolution in modified west Tennessee streams:
process, response, form. U.S. Government
Printing Office, Denver, Colorado. U.S. Geologi-
cal Survey Professional Paper 1470.
Simon, A., and P.W. Downs. 1995. An interdiscipli-
nary approach to evaluation of potential
instability in alluvial channels. Geomorphology
12: 215-32.
Simon, A., and C.R. Hupp. 1992. Geomorphic and
vegetative recovery processes along modified
stream channels of West Tennessee. U.S.
Geological Survey Open-File Report 91-502.
Simons, D.B., and Ml. Albertson. 1963. Uniform
water conveyance channels in alluvial material.
Transactions of the American Society of Civil
Engineers (ASCE) 128(1): 65-167.
Simons, D.B., and F. Senturk. 1977. Sediment
transport technology. Water Resources Publica-
tions, Fort Collins, Colorado.
Skagen. Unpublished data, U.S. Geological Survey,
Biological Resources Division, Fort Collins,
Colorado.
Skinner, Q.D., J.E. Speck, Jr., M. Smith, and J.C.
Adams. 1984. Stream quality as influenced by
beavers within grazing systems in Wyoming.
Journal of Range Management 37: 142-146.
Smith, D.S., and PC. Hellmund. 1993. Ecology of
greenways: design and function of linear
conservation areas. University of Minnesota
Press, Minnesota.
Smith, B.S., and D. Prichard. 1992. Management
techniques in riparian areas. BLM Technical
Reference 1737-6. U.S. Department of the
Interior, Bureau of Land Management.
Smock, L.A., E. Gilinsky, and D.L. Stoneburner.
1985. Macroinvertebrate production in a
southeastern United States blackwater stream.
Ecology 66: 1491-1503.
References
B-25
-------
Sparks, R. 1995. Need for ecosystem management
of large rivers and their flooodplains. BioScience
45(3): 170.
Spence, B.C., G.A. Lomnscky, R.M. Hughes, and
R.P. Novitski . 1996. An ecosystem approach to
salmonid conservation. TR-4501 -96-6057.
ManTech Environmental Research Services Corp.,
Corvallis, Oregon. (Available from the National
Marine Fisheries Service, Portland, Oregon.)
Stamp, N., and R.D. Ohmart. 1979. Rodents of
desert shrub and riparian woodland habitats in
the Sonoran Desert. Southwestern Naturalist
24: 279.
Stalnaker, C.B., K.D. Bovee, and TJ. Waddle. 1996.
Importance of the temporal aspects of habitat
hydraulics to fish population studies. Regulated
Rivers: Research and Management 12:145-153.
Stanford J.A., and J.V. Ward. 1988. The hyporheic
habitat of river ecosystems. Nature 335: 64-66.
Stanley, E.H., S.G. Fisher, and N.B. Grimm. 1997.
Ecosytem expansion and contraction in streams.
Biosdence 47(7): 427-435.
Stanley, S.J., and D.W. Smith. 1992. Lagoons and
ponds. Water Environment Research 64(4):
367-371, June.
Statzner, B., and B. Higler. 1985. Questions and
comments on the river continuum concept.
Can. J. Fish. Aquat. Sci. 42: 1038-1044.
Stauffer, D.F., and L.B. Best. 1980. Habitat
selection by birds of riparian communities:
evaluating effects of habitat alterations. Journal
of Wildlife Management 44(1): 1-15.
Stednick, J.D. 1991. Wildland water quality
sampling and analysis. Academic Press, San
Diego.
Steinman, A.D., C.D. Mclntire, S.V. Gregory, G.A.
Lamberti, and L.R. Ashkenas. 1987. Effects of
herbivore type and density on taxonomic
structure and physiognomy of algal assemblages
in laboratory streams. Journal of the North
American Benthoiogy Society 6: 175-188.
Stevens, I.E., B.T. Brown, J.M. Simpson, and R.R.
Johnson. 1977. The importance of riparian
habitat to migrating birds. In Proceedings of the
Symposium on Importance, Preservation and
Management of Riparian Habitat, tech coord.
R.R. Johnson and D.A. Jones, pp. 154-156. U.S.
Department of Agriculture Forest Service
General Technical Report RM-43, Rocky Mountain
Forest and Range Experimental Station, Ft.
Collins, Colorado.
Stoner, R., and T. McFall. 1991. Woods roads: a
guide to planning and constructing a forest
roads system. U.S. Department of Agriculture,
Soil Conservation Service, South National
Technical Center, Fort Worth, Texas.
Strahler, A.M. 1957. Quantitative analysis of
watershed geomorphology. American Geophysi-
cal Union Transactions 38: 913-920.
Strange, T.H., E.R. Cunningham, and J.W. Goertz.
1971. Use of nest boxes by wood ducks in
Mississippi. Journal of Wildlife Management 35:
786-793.
Sudbrock, A. 1993. Tamarisk control!: fighting
backan overview of the invasion, and a low-
impact way of fighting it. Restoration and
Management Notes 11: 31-34.
Summerfield, M.: 1991. Global geomorphology.
Longman, Harlow.
Svejcar, T.J., G.M. Riegel, S.D. Conroy, and J.D.
Trent. 1992. Establishment and growth
potential of riparian shrubs in the northern
Sierra Nevada. In Symposium on Ecology and
Management of Riparian Shrub Communities.
USDA Forest Service General Technical Report
INT-289. U.S. Department of Agriculture, Forest
Service.
Swanson, S. 1989. Using stream classification to
prioritize riparian rehabilitation after extreme
events. In Proceedings of the California Riparian
Systems Conference, pp. 96-101. U.S. Depart-
ment of Agriculture, Forest Service General
Technical Report PSW-110.
B-26
Stream Corridor
-------
Sweeney, B.W. 1984. Factors influencing life-
history patterns of aquatic insects. In The
ecology of aquatic insects, ed. V.H. Resh and
D.M. Rosenberg, pp. 56-100. Praeger, New York.
Sweeney, B.W. 1992. Streamside forests and the
physical, chemical, and trophic characteristics of
piedmont streams in eastern North America.
Water Science Technology 26: 1-12.
Sweeney, B.W. 1993. Effects of streamside
vegetation on macroinvertebrate communities
of White Clay Creek in eastern North America.
Stroud Water Resources Center, Academy of
Natural Sciences. Proceedings of the Academy of
Natural Sciences, Philadelphia 144: 291-340.
Swenson, E.A., and C.L. Mullins. 1985. Revegeta-
tion riparian trees in southwestern floodplains.
In Riparian ecosystems and their management:
reconciling conflicting uses, coord. R.R. Johnson,
C.D. Ziebell, D.R. Patton, PR Ffolliot, and R.H.
Hamre, pp. 135-139. First North American
Riparian Conference, USDA Forest Service
General Technical Report RM-120. Rocky
Mountain Forest and Range Experiment Station,
Fort Collins, Colorado.
Tarquin, P.A., and L.D. Baeder. 1983. Stream
channel reconstruction: the problem of designing
lower order streams. In Proceedings of
Symposium on Surface Mining, Hydrology,
Sedimentology and Reclamation, pp. 41-46.
Telis, PA. 1991. Low-flow and flow-duration
characteristics of Mississippi streams. U.S.
Geological Survey Water-Resources Investigations
Report 90-4087.
Temple, D.M., and J.S. Moore. 1997. Headcut
advance prediction for earth spillways. Transac-
tions ASAE 40(3): 557-562.
Terrell, J.W., and J. Carpenter, eds. In press.
Selected Habitat Suitability Index model evalua-
tions. Information and Technology Report, U.S
Department of the Interior, Washington, DC.
Teskey, R.O., and T.M. Hinckley. 1978. Impact of
water level changes on woody riparian and
wetland communities, vols. I, II, and III. FWS/
OBS-77/58, -77/59, and -77/60. U.S. Department
of Agriculture, Fish and Wildlife Service.
Theurer, F.D., K.A. Voos, and W.J. Miller. 1984.
Instream water temperature model. Instream
Flow Information Paper No. 16. USDA Fish and
Wildlife Service, Cooperative Instream Flow
Service Group, Fort Collins, Colorado.
Thomann, R.V., and J.A. Mueller. 1987. Principles
of surface water quality modeling and control.
Harper & Row, New York.
Thomas, J.W. ed. 1979. Wildlife habitat in
managed forests: the Blue Mountain of Oregon
and Washington. Ag. Handbook 553. U.S.
Department of Agriculture Forest Service.
Thomas and Bovee. 1993. Application and testing
of a procedure to evaluate transferability of
habitat suitability criteria. Regulated Rivers
Research and Management 8(3): 285-294,
August 1993.
Thomas, W.A., R.R. Copeland, N.K. Raphelt, and
D.N. McComas. 1993. User's manual for the
hydraulic design package for channels (SAM).
Draft report. U.S. Army Corps of Engineers
Waterways Experiment Station, Vicksburg,
Mississippi.
Thorne, C.R. 1992. Bend scour and bank erosion
on the meandering Red River, Louisiana. In
Lowland floodp/ain rivers: geopmorphological
perspectives, ed. P.A. Carling and G.E. Petts, pp.
95-115. John Wiley and Sons, Ltd., Chichester,
U.K.
Thorne, C.R., S.R. Abt, F.B.J. Barends, S.T. Maynord,
and K.W. Pilarczyk. 1995. River, coastal and
shoreline protection: erosion control using riprap
and armourstone. John Wiley and Sons, Ltd.,
Chichester, UK.
Thorne, C.R., R.G. Allen, and A. Simon. 1996.
Geomorphological river channel reconnaissance
for river analysis, engineering and management.
Transactions of the Institute for British Geography
21:469-483.
Thorne, C.R., H.H. Chang, and R.D. Hey. 1988.
Prediction of hydraulic geometry of gravel-bed
streams using the minimum stream power
concept. In Proceedings of the International
Conference on River Regime, ed. W.R. White.
John Wiley and Sons, New York.
References
B-27
-------
Thome, C.R., J.B. Murphey, and W.C. Little. 1981.
Bank stability and bank material properties in
the bluff line streams of North-west Mississippi.
Appendix D, Report to the Corps of Engineers
Vicksburg District under Section 32 Program,
Work unit 7, USDA-ARS Sedimentation Labora-
tory, Oxford, Mississippi.
Thorne, C.R., and A.M. Osman. 1988. River bank
stability analysis II: applications. Journal of
Hydraulic Engineering 114(2): 151-172.
Thorne, C.R., and L.W. Zevenbergen. 1985.
Estimating mean velocity in mountain rivers.
Journal of Hydraulic Engineering, ASCE 111 (4):
612-624.
Thumann, A., and R.K. Miller. 1986. Fundamentals
of noise control engineering. The Fairmont Press,
Atlanta.
Tiner, R. 1997. Keys to landscape position and
landform descriptors for United States wetlands
(operational draft). U.S. Fish and Wildlife Service,
Northwest Region, Hadley, Massachusetts.
Tiner, R., and Veneman. 1989. Hydric soils of New
England. Revised Bulletin C-183R. University of
Massachusetts Cooperative Extension, Amherst,
Massachusetts.
Toffaleti, F.B. 1968. A procedure for computation
of the total river sand discharge and detailed
distribution, bed to surface. U.S. Army Engineers
Waterways Experiment Station Technical Report
No. 5. Committee on Channel Stabilization.
Tramer, E.J. 1969. Bird species diversity: compo-
nents of Shannon's formula. Ecology 50(5): 927-
929.
Tramer, E.J. 1996. Riparian deciduous forest.
Journal of Field Ornithology 67(4)(Supplement):
44.
Trimble, S. 1997. Contribution of stream channel
erosion to sediment yield from an urbanizing
watershed. Science 278: 1442-1444.
United States Army Corps of Engineers (USACE).
1989a. Engineering and design: environmental
engineering for local flood control channels.
Engineer Manual No. 1110-2-1205. Depart-
ment of the Army, United States Army Corps of
Engineers, Washington, DC.
United States Army Corps of Engineers (USACE).
1989b. Sedimentation investigations of rivers
and reservoirs. Engineer Manual No. 1110-2-
4000. Department of the Army, United States
Army Corps of Engineers, Washington, DC.
United States Army Corps of Engineers (USACE).
1989c. Demonstration erosion control project.
General Design Memorandum No. 54 (Reduced
Scope), Appendix A. Vicksburg District,
Vicksburg, Mississippi.
United States Army Corps of Engineers (USACE).
1990. Vicksburg District systems approach to
watershed analysis for demonstration erosion
control project, Appendix A. Demonstration
Erosion Control Project Design Memorandum
No. 54. Vicksburg District, Vicksburg, Mississippi.
United States Army Corps of Engineers (USACE).
1991. Hydraulic design of flood control
channels. USACE Headquarters, EM111Q-2-
1601, Washington, DC.
United States Army Corps of Engineers (USACE).
1993. Demonstration erosion control project
Coldwater River watershed. Supplement I to
General Design Memorandum No. 54.
Vicksburg District, Vicksburg, Mississippi.
United States Army Corps of Engineers (USACE).
1994. Analyzing employment effects of stream
restoration investments. Report CPD-13.
Prepared by Apogee Research, Inc.; U.S.
Environmental Protection Agency, Washington,
DC; US Army Corps of Engineers, Institute for
Water Resources, Alexandria, Virginia.
United States Department of the Interior, Bureau of
Reclamation (USDI-BOR). 1997. Water measure-
ment manual. A Water Resources Technical
Publication. U.S. Government Printing Office,
Washington, DC.
B-28
Stream Corridor
-------
United States Department of Agriculture, Soil
Conservation Service. (USDA-SCS). 1977.
Adapted from Figure 6-14 on page 6-26 in U.S.
Department of Agriculture, Soil Conservation
Service 1977. Technical Release No. 25 Design
of open flow channels. 247pp. Figure 6-14 on
page 6-26 was adapted from Lane, E.W. 1952,
U.S. Bureau of Reclamation. Progress report on
results of studies on design of stable channels.
Hydrauic Laboratory Report No. HYD-352.
United States Department of Agriculture, Soil
Conservation Service. (USDA-SCS). 1983.
Selected statistical methods. In National
engineering handbook, Section 4. Hydrology,
Chapter 18.
United States Department of Agriculture, Natural
Resources Conservation Service (USDA-NRCS).
Field office technical guide. (Available at NRCS
county field office locations.)
United States Department of Agriculture, Natural
Resources Conservation Service (USDA-NRCS).
1992. Soil bioengineering for upland slope
protection and erosion reduction. In Engineering
field handbook, Part 650, Chapter 18.
United States Department of Agriculture, Natural
Resources Conservation Service (USDA-NRCS).
1994. Unpublished worksheet by Lyle Steffen,
NRCS, Lincoln, NE.
United States Department of Agriculture, Natural
Resources Conservation Service (USDA-NRCS).
1996a. Streambank and shoreline protection.
In Engineering field handbook, Part 650,
Chapter 16.
United States Department of Agriculture, Natural
Resources Conservation Service (USDA-NRCS).
1996b. America's private landA geography of
hope. U.S. Department of Agriculture,
Washington, DC. Program Aid 1548.
United States Department of Agriculture, Natural
Resources Conservation Service (USDA-NRCS).
1998. Stream visual assessment protocol (draft).
National Water and Climate Data Center,
Portland, Oregon.
United States Environmental Protection Agency
(USEPA). 1979. Handbook for analytic quality
control in water and wastewater laboratories.
EPA-600/4-79-019. U.S. Environmental Protec-
tion Agency, Environmental Monitoring and
Support Laboratory, Cincinnati, Ohio.
United States Environmental Protection Agency
(USEPA). 1983a. Interim guidelines and
specifications for preparing quality assurance
plans. QAMS-004/80, EPA-600/8-83-024. U.S.
Environmental Protection Agency, Washington,
DC.
United States Environmental Protection Agency
(USEPA). 1983b. Interim guidelines and
specifications for preparing quality assurance
project plans. QAMS-005/80, EPA-600/4-83-004.
U.S. Environmental Protection Agency,
Washington, DC.
United States Environmental Protection Agency
(USEPA). 1986a. Ambient water quality criteria
for dissolved oxygen. EPA 440/5-86/003.
Miscellaneous Report Series. U.S. Environmental
Protection Agency, Washington, DC.
United States Environmental Protection Agency
(USEPA). 1986b. Quality criteria for water
1986. EPA 440/5/86-001. U.S. Environmental
Protection Agency, Office of Water Regulations
and Standards, Washington, DC.
United States Environmental Protection Agency
(USEPA). 1989. Sediment classification methods
compendium. Draft final report. U.S.
Environmental Protection Agency, Office of
Water, Washington, DC.
United States Environmental Protection Agency
(USEPA). 1992. Storm water sampling guidance
document. U.S. Environmental Protection
Agency, Washington, DC.
United States Environmental Protection Agency
(USEPA). 1993. Watershed protection: catalog
of federal programs. EPA841-B-93-002. U.S.
Environmental Protection Agency, Office of
Wetlands, Oceans and Watersheds, Washington,
DC.
References
B-29
-------
United States Environmental Protection Agency
(USEPA). 1995a. Ecological restoration: a tool
to manage stream quality. U.S. Environmental
Protection Agency, Washington, DC.
United States Environmental Protection Agency
(USEPA). 1995b. Volunteer stream monitoring:
a method manual. EPA841-D-95-001. U.S.
Environmental Protection Agency, Washington,
DC.
United States Environmental Protection Agency
(USEPA). 1997. The quality of our nation's
water: 1994. EPA841R95006. U.S. Environ-
mental Protection Agency, Washington, DC.
United States Fish and Wildlife Service (USFWS).
1997. A system for mapping riparian areas in
the Western United States. National Wetlands
Inventory. Washington, DC. December.
United States Fish and Wildlife Service (USFWS).
1980. Habitat Evaluation Procedures (HEP) (ESM
102). U.S. Department of the Interior, Fish and
Wildlife Service, Washington, DC.
United States Fish and Wildlife Service (USFWS).
1981. Standards for the development of
Habitat Suitability Index models (ESM 103). U.S.
Department of the Interior, Fish and Wildlife
Service, Washington, DC.
United States Forest Service. 1965. Range seeding
equipment handbook. U.S. Forest Service,
Washington, DC.
van Der Valk, A.G. 1981. Succession in wetlands:
a Gleasonian approach. Ecology 62: 688-696.
Van Haveren, B.P. 1986. Management of instream
flows through runoff detention and retention.
Water Resources Bulletin WARBAQ 22(3):
399-404.
Van Home, B. 1983. Density as a misleading
indicator of habitat quality. Journal of Wildlife
Management 47: 893-901.
Van Winkle, W., H.I. Jager, and B.D. Holcomb.
1996. An individual-based instream flow model
for coexisting populations of brown and
rainbow trout. Electric Power Research Institute
Interim Report TR-106258. Electric Power
Research Institute.
Vannote, R.L., G.W. Minshall, K.W. Cummins, J.R.
Sedell, and C. E. Cushing. 1980. The River
Continuum Concept. Canadian Journal of
Fisheries and Aquatic Sciences 37(1): 130-137.
Vanoni, V.E., ed. 1975. Sedimentation engineering.
American Society of Civil Engineers, New York.
Verner, J. 1984. The guild concept applied to
management of bird populations. Environmental
Management 8: 1-14.
Verner, J. 1986. Future trends in management of
nongame wildlife: A researcher's viewpoint. In
Management of nongame wildlife in the
Midwest: a developing art, ed. J.B. Hale, L.B.
Best, and R.I. Clawson, pp. 149-171. Proceed-
ings of the 47th Midwest Fish and Wildlife
Conference, Grand Rapids, Michigan.
Vogel, R.M. and C.N. Kroll. 1989. Low-flow
frequency analysis using probability-plot
correlation coefficients. Journal of Water
Resources Planning and Management, ASCE
115(3): 338-357.
von Haartman, L. 1957. Adaptations in hole
nesting birds. Evolution 11: 339-347.
Walburg, C.H. 1971. Zip code H2O. In Sport
Fishing USA, ed. D. Saults, M. Walker, B. Hines,
and R.G. Schmidt. U.S. Department of the
Interior, Bureau of Sport Fisheries and Wildlife,
Fish and Wildlife Service. U.S. Government
Printing Office, Washington, DC.
Wallace, J.B., and M.E. Gurtz. 1986. Response of
Baetis mayflies (Ephemeroptera) to catchment
logging. American Midland Naturalist 115:
25-41.
Walters, M.A., R.O. Teskey, and T.M. Hinckley.
1978. Impact of water level changes on woody
riparian and wetland communities, vols. VII and
VIII. FWS/OBS-78/93, and -78/94. Fish and
Wildlife Service.
Ward, J.V. 1985. Thermal characteristics of
running waters. Hydrobiologia 125: 31-46.
Ward, J.V. 1989. The four-dimensional nature of
lotic ecosystems. Journal of the Northern
American Benthological Society 8: 2-8.
B-30
Stream Corridor
-------
Ward, J.V. 1992. Aquatic insect ecology. 1. Biology
and habitat. John Wiley and Sons, New York.
Ward, J.V, and J.A. Standford. 1979. Riverine
Ecosystems: the influence of man on catchment
dynamics and fish ecology. In Proceedings of
the International Large River Symposium. Can.
Spec. Publ. Fish. Aquat Sci. 106: 56-64.
Ward, R.C., J.C. Loftis, and G.B. McBride. 1990.
Design of water quality monitoring systems. Van
Nostrand Reinhold, New York.
Weitzel, R.L 1979. Periphyton measurements and
applications. In Methods and measurements of
periphyton communities: a review, ed. R.L.
Weitzel. Special publication 690. American
Society for Testing and Material.
Welsch, D.J. 1991. Riparian forest buffers:
Function and design for protection and
enhancement of water resources. USDA Forest
Service, Northeastern Area State and Private
Forestry Publication No. NA-PR-07-91. U.S.
Department of Agriculture Forest Service,
Radnor, Pennsylvania.
Wenger, K.F., ed. 1984. Forestry handbook. 2d ed.
Section 15, Outdoor recreation management,
pp. 802-885. John Wiley and Sons, New York.
Wesche, T.A. 1985. Stream channel modifications
and reclamation structures to enhance fish
habitat. Chapter 5 in The restoration of rivers
and streams, ed. J.A. Gore. Butterworth, Boston.
Wetzel, R.G. 1975. Limnology. W.B. Saunders Co.,
Philadelphia, Pennsylvania.
Wharton, C.H., W.M. Kitchens, E.C. Pendleton, and
T.W. Sipe. 1982. The ecology of bottomland
hardwood swamps of the Southeast: a commu-
nity profile. FWS/OBS-81/37. U.S. Fish and
Wildlife Service, Biological Services Program,
Washington, DC.
Wharton, G. 1995. The channel-geometry
methods: guidelines and applications. Earth
Surface Processes and Land forms 20(7):
649-660.
White, R.J., and O.M. Brynildson. 1967. Guidelines
for management of trout stream habitat in
Wisconsin. Technical Bulletin 39. Department of
Natural Resources, Madison, Wisconsin.
White, W.R., R. Bettess, and E. Paris. 1982.
Analytical approach to river regime. Proceedings
of the ASCE. Journal of the Hydraulics Division
108(HYLO): 1179-1193.
White, W.R., E. Paris, and R. Bettess. 1981. Tables
for the design of stable alluvial channels. Report
IT208. Hydraulics Research Station, Wallingford.
Whitlow, T.H., and R.W. Harris. 1979. Flood
tolerance in plants: a state-of-the-art review.
Environmental and Water Quality Operational
Studies, Technical Report E-79-2. U.S. Army
Corps of Engineers Waterways Experiment
Station, Vicksburg, Mississippi.
Wilde, Franceska. 1997. Personal communication.
Williams, D.T., and P.Y. Julien. 1989. Examination
of stage-discharge relationships of compound/
composite channels. In Channel flow and
catchment runoff: Proceedings of the Interna-
tional Conference for Centennial of Manning's
Formula and Kuichling's Rational Formula,
University of Virginia, ed. B.C. Yen, pp. 478-488.
Williams, G.W. 1978. Bankfull discharge of rivers.
Water Resources Research 14: 1141 -1154.
Williams, G.W. 1986. River meanders and channel
size. Journal of Hydrology 88: 147-164.
Williams, and M.G. Wolman. 1984. Downstream
effects of dams on alluvial rivers. U.S. Geological
Survey Professional Paper 1286.
Williamson, S.C., J.M. Bartholow, and C.B
Stalnaker. 1993. Conceptual model for quanti-
fying pre-smolt production from flow-dependent
physical habitat and water temperature.
Regulated Rivers: Research and Management 8:
15-28.
Wilson, K.V., and D.P. Turnipseed. 1994. Geomor-
phic response to channel modifications of Skuna
River at the State Highway 9 crossing at Bruce,
Calhoun County, Mississippi. U.S. Geological
Survey Water-Resources Investigations Report
94-4000.
References
B-31
-------
Wilson, M.F., and S.W. Carothers. 1979. Avifauna
of habitat islands in the Grand Canyon. SWNat.
24:563-576.
Wolman, M.G. 1954. A method of sampling
coarse river-bed material. Transactions of the
American Geophysical Union 35(6): 951-956.
Wolman, M.G. 1955. The natural channel of
Brandywine Creek, Pennsylvania. U.S Geological
Survey Professional Paper No. 271.
Wolman, M.G. 1964. Problems posed by sedi-
ments derived from construction activities in
Maryland. Maryland Water Pollution Control
Commission. January.
Wolman, M.G. and L B. Leopold. 1957. River
flood plains: some observations on their
formation. USGS Professional Paper 282C.
Wolman, M.G. and J. P. Miller. 1960. Magnitude
and frequency of forces in geomorphic process.
Journal of Geology 68: 54-74.
Woodyer, K.D. 1968. Bankfull frequency in rivers.
Journal of Hydrology 6: 114-142.
Yalin, M.S. 1971. Theory of hydraulic models.
MacMillan. London.
Yang, C.T. 1971. Potential energy and stream
morphology. Water Resources Research 7(2):
311-322.
Yang, C.T. 1973. Incipient motion and sediment
transport. Proceedings of the American Society
of Civil Engineers, Journal of Hydraulic Division
99 (HY10, Proc. Paper 10067.): 1679-1704.
Yang, C.T. 1983. Minimum rate of energy
dissipation and river morphology. In proceedings
of D.B. Simons Symposium on Erosion and
Sedimentation, Colorado State University, Fort
Collins, Colorado, 3.2-3.19.
Yang, C.T. 1984. Unit stream power equation for
gravel. Proc. Am. Soc. Civ. Engrs, J. Hydaul. Div.
110(HY12): 1783-1797.
Yang, C.T. 1996. Sediment transport theory and
practice. The McGraw-Hill Companies, Inc. New
York.
Yang, C.T, and C.S. Song. 1979. Theory of
minimum rate of energy dissipation. Proc. Am.
Soc. Civ. Engrs, J. Hydaul. Div., 105(HY7):
769-784.
Yang, C.T, and J.B. Stall. 1971. Note on the map
scale effect in the study of stream morphology.
Water Resources Research 7(3): 709-712.
Yang, C.T, and J.B. Stall. 1973. Unit Stream
Power in Dynamic Stream Systems, Chapter 12
in Fluvial Geomorphology, ed. M. Morisawa. A
proceeding volume of the Fourth Annual
Geomorophology Symposia Series, State
University of New York, Binghamton.
Yang, C.T, M.A. Trevino, and F. J.M. Simoes. 1998.
Users Manual for GSTARS 2.0 (Generalized
Stream Tube Model for Alluvial River Simulation
version 2.0). U.S. Bureau, Technical Service
Center, Denver, Colorado.
Yoakum, J., W.P Dasmann, H.R. Sanderson, C.M.
Nixon, and H.S. Crawford. 1980. Habitat
improvement techniques. In Wildlife manage-
ment techniques manual, 4th ed., rev., ed. S.D.
Schemnitz, pp. 329- 403. The Wildlife Society,
Washington, DC.
Yorke, T.H., and W.J. Herb. 1978. Effects of
urbanization on streamflow and sediment
transport in the Rock Creek and Anacostia River
Basins, Montgomery County, Maryland 1962-74.
U.S. Geological Survey Professional Paper 1003.
U.S. Geological Survey.
Yuzyk, T.R. 1986. Bed material sampling in gravel-
bed streams. Report IWD-HQ-WRB-SS-86-8.
Environment Canada, Inland Waters Directorate,
Water Resources Branch, Sediment Survey
Section.
Zalants, M.G. 1991. Low-flow frequency and flow
duration of selected South Carolina streams
through 1987. U.S. Geological Survey Water-
Resources Investigations Report 91-4170. U.S.
Geological Survey.
B-32
Stream Corridor
-------
Index
Adaptive management, 6-37, 9-32
Aggradation
regression functions, 7-55
Agriculture
vegetative clearing, 3-14
hypothetical condition and
restoration response, 8-83
instream modifications, 3-14
irrigation and drainage, 3-15
restoration, 8-83
sediment and contaminants, 3-15
soil exposure and compaction, 3-15
Alternatives
design, 5-17
restoration alternatives, 5-17
supporting analyses, 5-25
Aquatic habitat, 2-59
subsystems, 2-59
Aquatic vegetation, 2-63
B
Backwater
computation, 7-24
effects, 7-23
Bank stability, 7-57
bank erosion, 8-45
bank stability check, 8-44
charts, 7-60
critical bank heights, 7-60
protection measures, 8-46
qualitative assessment, 7-57
quantitative assessment, 7-59
Bank stabilization, 8-45, 8-61
anchored cutting systems, 8-64
geotextile systems, 8-65
trees and logs, 8-66
Bank restoration, 8-61
inspections, 9-23
Bankfull discharge, 1-17, 7-10
field indicators, 7-10
Benthic invertebrates, 2-64
benthic rapid bioassessment, 7-82
Beaver
ecosystem impacts, 8-26
impact of dams, 2-58
transplanting, 8-26
Biological diversity
complexity, 7-78
evaluating indices, 7-84
in developing goals and objectives,
5-6
Index of Biotic Integrity, 7-79
measures of diversity, 7-79
special scale, 7-79
standard of comparison, 7-83
subsets of concern, 7-79
Buffers, 8-11
forested buffer strips, 8-89
multispecies riparian buffer system,
8-87
requirements, 8-90
urban stream buffers, 8-72
c
Channel, 1-12,
equilibrium, 1-13
scarp, 1-12
size, 1-13
thalweg, 1-12
Channel form, 1-26
anastomosed streams, 1-27
braided streams, 1-27
predicting stable type, 8-30
Channel incision, 1-20
Channel slope, 2-22
longitudinal profiles, 2-22
Channel cross section, 2-23
composite and compound cross
sections, 7-23
field procedures, 7-24
site/reach selection, 2-23, 7-23
Channel evolution models, 7-30
advantages of, 7-34
applications of geomorphic
analysis, 7-37
limitations of, 7-36
Channel-forming (or dominant)
discharge, 1-16, 7-3, 7-8
determining from recurrence
interval, 7-4, 7-12
determining from watershed
variables, 7-15
mean annual flow, 7-15
Channel models, 8-40
computer models, 8-41
physical models, 8-41
Channel restoration, 8-28
dimensions, 8-32, 8-37
inspection, 9-23
maintenance, 9-26
moving beds, known slope, 8-38
moving beds, known sediment
concentration, 8-39
reconstruction procedures, 8-28
reference reach, 8-33
shape, 8-43
Channel roughness, 2-24
formation of aquatic habitat, 2-25
in meandering streams, 2-25
Channel stability
bank, 7-50
bed, 7-51
local, 7-51
systemwide, 7-51
Channel widening, 7-60
predictions, 7-62
Channelization and diversions, 3-8
restoration design, 8-79
CompMech (compensatory mecha-
nisms), 7-92
use with PHABSIM, 7-92
Conditions in stream corridor, 4-19
causes of impairment, 4-23
condition continuum, 4-22
management influence, 4-26
Conduit function, 2-82
Connectivity and width, 2-79, 8-4,
8-17
reference stream corridor, 8-7
restoration design, 8-20
Conservation easements, 6-7
Contouring, 9-13
Cost components and analysis, 5-21
benefits evaluation, 5-29
cost-effectiveness analysis, 5-26
data requirements, 5-21
decision making, 5-28
estimations, 6-29
incremental cost analysis, 5-27
Cross section surveys, 7-53
Cultural resources, 9-8
D
Dams
as a disturbance, 3-7
best management practices, 8-77
effects on stream corridors, 8-77
Glen Canyon Dam spiked flow
experiment, 3-9
removal, 8-78
Data analysis and management, 7-72
costs, 6-30
Degradation
regression functions, 7-54
Design, 8-1
Discharge, 1-16
continuity equation, 7-17
design discharge for restoration,
8-29
measurement, 7-25
Drainage, for implementation, 9-11
Dynamic equilibrium, 1-1, 2-86
Disturbance, 2-87, 3-1
Arnold, MO flood, 3-5
biological, 3-6, 7-96
broad scale, 3-3
causal chain of events, 3-1
chemical, 3-6
natural disturbances, 3-3
physical, 3-6
Ecological Restoration, 1-3
Ecosystem
internal/external movement model,
1-3
stream-riparian, 2-53
relationship btw. terrestrial/aquatic
ecosystems, 2-75
river floodplain, 2-53
Effective discharge, 1-17 , 7-13
Erosion, 2-15, 2-27,
control of, 2-27, 9-4
Environmental impact analysis, 5-30
Eutrophication, 2-73
Index
B-33
-------
Evaluation, 6-34, 6-41
baseline characterization, 9-29
effectiveness monitoring, 9-32
fish barrier modifications, 9-36
human interest, 9-38, 9-46
implementation monitoring, 9-32
parameters, 9-32
performance evaluation, 9-29
reference sites, 9-35
risk assessment, 9-29
trend assessment, 9-29
validation monitoring, 9-32
Evaporation, 2-6
Evapotranspiration, 2-7
Exotic species, 3-10
control, 8-79
salt cedar, 3-72
Western U.S., 3-7?
F
Fauna
aquatic fauna, 2-63
beaver (see Beaver above)
benthic invertebrates, 2-63
birds, 2-57
fish, 2-65
habitat features, 2-56
mammals, 2-58
mussels, 2-67
reptiles and amphibians, 2-57
Fencing, 9-20
Filter and barrier functions, 2-84
edges, 2-85
Fish, 2-65
barriers, 8-75, 9-36
bioindicators, 7-83
feeding and reproduction
strategies, 2-66
managing restoration, 9-46
species richness, 2-65
Floodplain, 1-12
hydrologic floodplain, 1-18
topographic floodplain, 1-18
flood storage, 1-18
lag time, 1-18
lateral accretion, 2-26
stability, 2-24
vertical accretion, 2-26
Floodplain landforms and deposits,
1-19
backswamps, 1-19
chute, 1-19
clay plug, 1-19
meander scroll, 1-19
natural levees, 1-19
oxbow, 1-19
oxbow lake, 1-19
restoration of microrelief, 8-8
splays, 1-19
Flood-pulse concept, 1-21
Flow
allowable velocity check, 8-48, 8-51
allowable stress check, 8-48, 8-51
baseflow, 1-14,2-13
daily mean streamflow, 7-6
ecological impacts, 2-15
ephemeral streams, 1-16
effluent or gaining reaches, 1-16
impact on fauna, 2-68
influent or "losing" reaches, 1-16
intermittent streams, 1-16
mean annual flow, 7-15
peak flow, 7-6
perennial streams, 1-16
stormflow, 1-14
sources of data, 7-6
uniform flow, 7-20
Flow duration, 2-14
flow duration curve, 7-3
Flow frequency, 2-14, 7-4
flood frequency analysis, 7-4, 7-7
low-flow frequency analysis, 7-7
Food patches, 8-25
Forests and forestry
buffer strips, 8-89
managing restoration, 9-42
site preparation, 3-17
transportation, 3-17, 8-88
tree removal, 3-16
Functions, 2-78
barrier, 2-78
conduit, 1-8,2-78
filter, 2-78
habitat, 2-78
sink, 2-78
source, 2-78
Funding,
organization, 4-9
restoration implementation, 6-2
Geomorphic assessment, 7-26
Geomorphology, 2-15
Goals and Objectives, 5-12, 5-14
desired future conditions, 5-3,
5-12
responsiveness, 5-74
restoration constraints and issues,
5-7
restoration goals, 5-12
restoration objectives, 5-13
scale considerations, 5-3
self-sustainability, 5-74
tolerance, 5-74
value, 5-74
vulnerability, 5-74
Grazing
loss of vegetative cover, 3-18
physical impacts, 3-19
restoration, 8-90, 9-43
Greentree reservoirs, 8-24
Ground water
aquifer, 2-10
aquitards, 2-10
capillary fringe, 2-10
confined aquifer, 2-11
pellicular water, 2-10
phreatic zone, 2-11
recharge area, 2-11
springs, seeps, 2-11
unconfined aquifer, 2-11
vadose zone, 2-10
H
Habitat Evaluation Procedures (HEP),
7-87
Habitat functions, 2-78
edge and interior, 2-87, 8-21
Habitat Recovery (instream), 8-70
procedures, 8-71
Hydraulic geometry
channel planform, 7-47
hydraulic geometry curves Salmon
River, 7-43
hydraulic geometry theory, 7-41,
8-36
meander geometry, 7-47,7-48,
7-49
regime formulas, 7-49
regime theory, 7-44
regional curves, 7-44
relations based on mean annual
discharge, 7-41
stability assessment, 7-44
Hydrologic cycle, 2-3
Hydrologic unit cataloging, 1-9
I
Indicator species, 7-76
aquatic invertebrates
habitat evaluation procedures,
7-78
riparian response guilds, 7-78
selecting indicators, 7-77
Infiltration, 2-8
infiltration capacity, 2-8
infiltration rate, 2-8
porosity, 2-8
Implementing restoration, 6-2
construction, 9-12
emergency maintenance, 9-26
flow diversion, 9-14
minimizing disturbance, 9-4
plant establishment, 9-15
remedial maintenance, 9-26
scheduled maintenance, 9-26
site preparation, 9-3, 9-10
staging areas, 9-4
work zone, 9-3
Inspection, 9-21
Instream Flow Incremental Methodol-
ogy (IFIM), 5-24,7-88,
B-34
Stream Corridor
-------
Instream structures, 8-72
design, 8-72
engineered log jams, 9-30
inspection, 9-23
Interception, 2-4
precipitation pathways, 2-5
Irrigation, 9-20
Landscape scale, 1-7
in goals and objective develop-
ment, 5-5
Land use
design approaches for common
effects, 8-76
developing goals and objectives,
5-3
summary of disturbance activities,
3-26
Log jams, engineered, 9-30
Longitudinal zones, 1-24
Longitudinal profile, 2-23, 8-43
adjustments, 2-23
M
Managing restoration, 9-40
Manning's equation, 7-17
direct solution for Manning's n,
7-18
Froude number, 7-27
indirect solution for Manning's n,
7-19
Manning's n in relation to
bedforms, 7-2?
Monitoring, 6-22
acting on results, 6-37
dissemination of results, 6-39
documenting and reporting, 6-38
inspection, 9-21
monitoring plan, 6-23, 6-25, 6-29,
6,33
performance criteria, 6-24
level of effort, 6-31
parameters, and methods, 6-26
target conditions, 6-26
types of data, 6-31
Montgomery and Buffington
classification system, 7-29
Mining
altered hydrology, 3-19
contaminants, 3-20
reclamation, 8-96
soil disturbance, 3-20
vegetative clearing, 3-20
Mulches, 9-19
N
Nest structures, 8-25
Oak Ridge Chinook salmon model
(ORCM), 7-92
Organic material, 2-73
autochthonous, 1-30, 2-73
allochthonous, 1-30, 2-73
heterotrophic, 1-30
Organizing restoration
advisory group, 4-4
boundary setting, 4-3
commitments, 6-10
contractors, 6-10
characteristics of success, 6-17
decision maker, 4-4
decision structure, 4-10
dividing responsibilities, 6-4, 6-6
documentation, 4-13
information sharing, 4-12
permits, 6-13
schedules, 6-12
scoping process, 4-3
sponsor, 4-4
technical teams, 4-5, 6-8
tools, 6-3
volunteers, 6-8
Overland flow, 2-11
depression storage, 2-11
Horton overland flow, 2-12
surface detention, 2-12
Physical Habitat Simulation Model
(PHABSIM), 7-88
time series simulations, 7-91
use with CompMech, 7-92
Physical structure
corridor, 1-3
patch, 1-3
matrix, 1-3
mosaic, 1-3
Pools and riffles, 1-28, 2-22
riffle spacing, 8-43
Problem/opportunities identification,
4-16
baseline data, 4-17
community mapping, 4-17
data analysis, 4-19
data collection, 4-16
historical data, 4-17
problem/opportunity statements,
4-27
reference condition, 4-20
reference reach, 4-20
reference site, 4-20
Proper Functioning Condition (PFC),
7-39
Public outreach, 4-12
tools, 4-13
Quality assurance and quality control
costs, 6-29
restoration planning, 5-8
sampling, 7-73
Rapid bioassessment, 7-80
Reach file/National Hydrography
Dataset, 1-9
Reach scale, 1-10
in developing goals and objectives,
5-7
Rehabilitation, 1-3
Recovery, 2-87
Recreation, 3-21
restoration design, 8-97
Regional hydrological analysis, 7-15
Regional scale, 1-6
Rehabilitation, 1-3
Resistance, 2-87
Resilience, 2-87
in Eastern upland forests, 3-4
Restoration, 1-2,1-3
Riffles (see Pools and riffles)
Risk assessment, 5-29
River continuum concept, 1-30
Riverine Community Habitat
Assessment and Restoration
Concept Model (RCHARC), 7-91
Rosgen stream classification system,
7-29
Runoff, 2-11
Quick return flow, 2-13
Salmonid population model
(SALMOD), 7-93
Sampling
automatic, 7-65
chain of custody, 7-70
discrete versus composite, 7-66
field analysis, 7-67
field sampling plan, 6-30
frequency, 7-63, 6-32
grab, 7-65
labeling, 7-69
laboratory sample analysis, 6-30
manual, 7-65
packaging and shipping, 7-70
preparation and handling, 7-69
preservation, 7-69
site selection, 7-64
timing and duration, 6-32
Saturated overland flow, 2-13
Scarp, 1-12
Schumm
classification system, 7-29
equation, 2-21
Sediment
ecological and water quality
impacts, 2-26
Sediment control, 9-4
hay bales, 9-5
silt fence, 9-5
Sediment deposition, 2-15
Sediment sampling
analysis, 7-71
collection techniques, 7-71
Index
B-35
-------
Sediment transport, 2-15, 8-53
bed load, 2-18
bed-material load, 2-18, 2-19
budget, 8-56
discharge functions, 8-55
HEC-6, 8-54
impact on habitat, 2-26
impact on water quality, 2-26
measured load, 2-19
particle movement, 2-17
processes, 7-57
saltation, 2-17
sediment load, 2-18
sediment rating curve, 7-13, 8-29
stream competence, 2-16
stream power, 2-19, 8-52
suspended bed material load, 2-18
suspended load, 2-18, 2-19
suspended sediment discharge,
2-18
tractive (shear) stress, 2-16, 8-38,
8-48, 8-51
unmeasured load, 2-19
wash load, 2-18, 2-79
Single-thread streams, 1-26
Sinuosity, 1-27
affecting slope, 2-22
meander design, 8-34, 8-36
Site access, 6-15, 9-4
access easement, 6-16
drainage easement, 6-16
fee acquisition, 6-16
implementation easement, 6-16
right of entry, 6-15
Site clearing, 9-10
Species requirements, 7-86, 8-7
Specific gauge analysis, 7-52
Soil
compaction, 8-9
ecological role of, 2-51
depleted matrix, 2-49
functions, 2-45
hydric soils, 2-48
microbiology, 2-46, 2-51, 8-9
salinity, 8-10
soil surveys, 8-9
topographic position, 2-47
type, 2-46
wetland, 2-48
Soil bioengineering, 8-23, 8-61
geotechnical engineering, 9-13
Soil moisture, 2-9
evaporation, 2-6
deep percolation, 2-9
field capacity, 2-9
permanent wilting point, 2-9
relationship with temperature,
2-47
Source and sink functions, 2-86
Spatial scale, 1-3
landscapes, 1-7
region, 1-6
reach, 1-10
watershed, 1-8
Stability (in stream and floodplain),
2-20, 2-87
assessment, 8-44
allowable stress check, 8-48
allowable velocity check, 8-48
controls, 8-64
horizontal stability, 8-45
vertical stability, 8-44
Storm hydrograph, 1-15
after urbanization, 7-75
recession limb, 1-15
rising limb, 1-15
Stream classification, 7-26, 7-85
applications of geomorphic
analysis, 7-37
advantages, 7-27
alluvial vs. non-alluvial, 7-27
limitations, 7-27
use in restoring biological
conditions, 7-86
Stream corridor, 1-1
adjustments, 2-21
common features, 1-12
Stream corridor scale, 1-10
in developing goals and objectives,
5-6
Stream health
visual assessment, 7-76
Stream instability, 7-50
bed stability, 7-51
local, 7-51
system wide, 7-51
Stream order, 1-25
as a classification system, 7-28
stream continuum concept, 1-30
Stream scale, 1-10
Stream stability (balance), 1-14, 2-20
Stream system dynamics, 7-48
Substrate, 2-71
bed material particle size
distribution, 7-25, 8-28
hyphorheic zone, 2-72
pebble count, 7-25
vertical (bed) stability
Subsurface flow, 2-12
Temporal scale, 1-11
Terrace, 1-20
formation, 1-20
numbering, 1-21
Thalweg, 1-12
profiles, 7-53
surveys, 7-53
Transitional upland fringe, 1-12, 1-20
Transpiration, 2-5
Two-dimensional flow modeling,
7-90
u
Urbanization, 3-22
altered channels, 3-24. 8-97
altered hydrology, 3-23, 8-97
design tools, 8-101
habitat and aquatic life, 3-25
inspection program, 9-25
runoff controls, 8-99
sediment controls, 8-100
sedimentation and contaminants,
3-24
V
Valley form, 8-4
Vegetation
across the stream corridor, 1-21
along the stream corridor, 1-29
canyon effect, 2-54
distribution and characteristics,
2-51
flooding tolerances, 7-96, 8-22
horizontal complexity, 2-52, 8-17
internal complexity (diversity),
2-51
landscape scale, 2-53
structure, 2-55
stream corridor scale, 2-53
vertical complexity (diversity),
2-55, 8-21
zonation, 7-96
Vegetation-hydroperiod modeling,
7-94
use in restoration, 8-23
Vegetation restoration, 8-14
existing vegetation, 8-11
inspection, 9-24
maintenance, 9-28
restoration species, 8-10
revegetation, 8-14, 9-15
w
Waste disposal, sanitation, 9-9
Water surface
energy equation, 7-21
profile, 7-78
slope survey, 7-24
Water temperature, 2-28
effects of cover, 2-68
impacts of surface versus ground
water pathways, 2-28
impacts on fauna, 2-68
sampling, 7-68
thermal loading, 2-28
B-36
Stream Corridor
-------
Water quality
acidity, 2-30, 2-31
alkalinity, 2-30, 2-31
biochemical oxygen demand (BOD),
2-32
dissolved oxygen, 2-31, 2-70,
(sampling) 7-68
iron, 2-29
metals, 2-44
nitrogen, 2-35
pH, 2-30, 2-71, (sampling) 7-68
phosphorus, 2-35
restoration implementation, 9-6
salinity, 2-29
toxic organic chemicals, 2-38
Watershed, 1-24
designing for drainage and
topography, 8-8
drainage patterns, 1-25
watershed scale, 1-8
Wetlands, 2-60
functions, 2-61
hydrogeomorphic approach, 2-62
National Wetlands Inventory, 2-67
palustrine wetlands, 2-62
plant adaptation, 2-49
USFWS Classification of Wetlands
and Deepwater Habitats of the
United States, 2-61
Width (see Connectivity and width)
Index B-37
-------
------- |