"BstreamMechanics
A Function-Based Framework
for Stream Assessment & Restoration Projects
EPA 843-K-12-006 » May 2012
-------
Title: A Function-Based Framework for Stream Assessments and Restoration Projects
Date: May 2012
Prepared By:
• Will Harman, Stream Mechanics, Raleigh, NC (Chapters 1, 2, 4, 5, 6, 7, 8, 11)
• Richard Starr, US Fish and Wildlife Service, Chesapeake Bay Field Office, MD (Chap-
ters 1,4,8, 11)
• Melanie Carter, Carter Land and Water (Chapter 5, 8, 9, 10)
• Kevin Tweedy, Michael Baker Corporation, Pittsburgh, PA (Chapter 3, 5)
• Micky Clemmons, Michael Baker Corporation, Pittsburgh, PA (Chapter 10)
• Kristi Suggs, Michael Baker Corporation, Pittsburgh, PA (Chapter 9)
• Christine Miller, Michael Baker Corporation, Pittsburgh, PA (Chapter 8)
Appropriate Citation:
Harman, W, R. Starr, M. Carter, K. Tweedy, M. Clemmons, K. Suggs, C. Miller. 2012.
A Function-Based Framework for Stream Assessment and Restoration Projects. US Environmen-
tal Protection Agency, Office of Wetlands, Oceans, and Watersheds, Washington, DC
EPA 843-K-12-006. '
The findings and conclusions in this document are those of the authors and do not
necessarily represent the views of the US Fish and Wildlife Service (FWS) or the US
Environmental Protection Agency (EPA).
Authors' Note:
This document provides a new framework for approaching stream assessment and
restoration from a function-based perspective; as such, it will benefit from review, com-
ments, and example experiences and applications. Please share these with the authors so
the concepts, examples and templates can be revised and expanded. Contact any one of
the following: Will Harman, lead author (wharman@stream-mechanics.com, 919-747-9448),
Brian Topping, EPA project sponsor (topping.brian@epa.gov, 202-566-5680) or Rich Starr,
FWS project sponsor (rich_starr@fws.gov, 410-573-4583).
A Function-Based Framework » May 2012
-------
ACKNOWLEDGMENTS
This document would not have been possible without the assistance of numerous
scientists from EPA and other organizations. Special thanks to Palmer Hough and Brian
Topping with EPA headquarters for the idea to provide training and support regarding
stream functional assessments, for their commitment to secure project funding, and for
their careful review and guidance throughout all stages of the project. The FWS is also
recognized for providing in-kind financial support and project oversight.
The Framework presented in this document was tested through a pilot workshop at
the FWS National Conservation Training Center in the summer of 2010. EPA staff from
around the country attended the workshop and provided comments on how to improve
the Framework and workshop. They also provided real-world examples of stream im-
pacts and restoration needs from various regions that could be used to develop case
studies. These scientists and managers included: Eric Somerville, Ed Reiner, Robert
Montgomerie, Stephanie Chin, Carol Petrow, David Rider, Bill Ainslie, Mara Lindsley,
Sue Elston, Melissa Gebien, Melanie Haveman, Scott McWhorter, Catherine Holston,
Jason Daniels, Richard Clark, Toney Ott, Tracie Nadeau, Linda Storm, Brent Johnson,
Greg Pond, Joy Gillespie, Brian Topping and Palmer Hough.
Special thanks to Brian Topping, Palmer Hough, Tracie Nadeau, Bill Ainslie, Eric
Somerville, Bob Lord, Julia McCarthy, Jason Daniels, Brent Johnson, Ken Fritz, Greg Pond,
Craig Fischenich, Chris Noble, Rich Sumner, Linda Storm and Toney Ott for additional
review comments and guidance as the second version of the document was prepared.
Their insight and expertise greatly improved the content and breadth of the document.
A Function-Based Framework » May 2012
-------
TABLE OF CONTENTS
GLOSSARY OF TERMS
EXECUTIVE SUMMARY
CHAPTER 1:
INTRODUCTION
1.1 Document Overview
1.2 What the Document Does and Does Not Provide
1.3 Project Partnerships
CHAPTER 2: OVERVIEW OF FEDERAL COMPENSATORY MITIGATION REGULATIONS
2.1 Overview
2.2 Resources
13
14
15
16
19
19
20
CHAPTER 3: WATERSHED AND RIVER CORRIDOR PROCESSES
3.1 Watershed Processes
3.2 River Corridor Processes
3.3 Channel Form
3.4 Overview of Stream Functions
3.5 American River Regions
3.6 Stream Classification
3.7 Watershed and Stream Restoration
3.8 Priority Levels of Restoration
3.9 Importance of Site Selection in River Restoration
21
21
23
23
26
27
30
31
35
39
CHAPTER 4: THE STREAM FUNCTIONS PYRAMID
4.1 Functional Objectives for Stream Restoration
4.2 The Stream Functions Pyramid
4.3 Stream Functions Pyramid: Broad-Level View
4.4 Stream Functions Pyramid: Function-Based Parameters
4.5 Stream Functions Pyramid: Measurement Methods
4.6 Function-Based Parameters and Measurement Method:
Descriptions by Category
4.7 Stream Functions Pyramid: Performance Standards
4.8 Stream Functions Pyramid and Restoration Activities
4.9 Application of the Stream Functions Pyramid Framework
4.10 Summary
41
41
44
44
48
50
55
59
60
64
69
A Function-Based Framework » May 2012
-------
Table of Contents
CHAPTER 5:
CHAPTER 6:
CHAPTER 7:
CHAPTER 8:
CHAPTER 9:
REFERENCE STREAMS
5.1 Use of Reference Reach Data in this Document
5.2 Background
5.3 Site Selection
5.4 Assessing Reference Reaches
5.5 Monitoring Approaches
HYDROLOGY
6.1 Parameter: Channel-Forming Discharge
6.2 Parameter: Precipitation/Runoff Relationship
6.3 Parameter: Flood Frequency
6.4 Parameter: Flow Duration
HYDRAULICS
7.1 Parameter: Floodplain Connectivity
7.2 Parameter: Flow Dynamics
7.3 Parameter: Groundwater and Surface Water Exchange
GEOMORPHOLOGY
8.1 Parameter: Sediment Transport Competency
8.2 Parameter: Sediment Transport Capacity
8.3 Parameter: Large Woody Debris Transport and Storage
8.4 Parameter: Channel Evolution
8.5 Parameter: Bank Migration/Lateral Stability
8.6 Parameter: Riparian Vegetation
8.7 Parameter: Bed Form Diversity
8.8 Parameter: Bed Material Characterization
PHYSICOCHEMICAL
9.1 Parameter: Water Quality
9.2 Parameter: Nutrients
9.3 Parameter: Organic Carbon
71
71
71
74
76
80
83
84
87
89
91
95
96
105
110
115
116
118
121
124
134
145
155
164
169
170
182
187
A Function-Based Framework » May 2012
-------
Table of Contents
CHAPTER 10: BIOLOGY 193
10.1 Parameter: Microbial Communities 194
10.2 Parameter: Macrophytes 199
10.3 Parameter: Macroinvertebrate Communities 204
10.4 Parameter: Fish Communities 209
10.5 Parameter: Landscape Connectivity 214
CHAPTER 11: APPLICATION OFTHE STREAM FUNCTIONS PYRAMID 217
11.1 Adding Parameters, Measurements and Performance Standards 217
11.2 Developing Goals and Objectives 217
11.3 Function-Based Stream Assessments 223
11.4 Key Parameters 228
11.5 Reviewing Existing Stream Assessments 233
11.6 Developing Debits and Credits 234
11.7 Steps to Developing Debits and Credits 246
REFERENCES 249
APPENDICES 285
A. STREAM FUNCTIONS PYRAMID
A. Overview Graphic
B. Functions & Parameters Graphic
C. Parameter & Measurement Method Table
D. Performance Standard Table
B. APPLICATION SCENARIOS
PERMITTED IMPACT SCENARIOS (DEBITS)
1. Culvert installations
2. Channelization and Bank Hardening
3. Surface Mining of High-Gradient Streams
STREAM MITIGATION SCENARIOS (CREDITS)
1. Restoration of Incised Channels in Alluvial Valleys
2. Restoration of Stream Flow for Channels That Have Excessive Water Withdrawal
3. Salmonid Fish Passage and Habitat Restoration
4. Restoration of High-Gradient, Headwater Streams
A Function-Based Framework » May 2012
-------
GLOSSARY OF TERMS
Biology Function: Level 5 functions of the Stream Functions Pyramid that involve the
biodiversity and the life histories of aquatic and riparian organisms. These functions are
placed at the top of the Pyramid because they are affected by all underlying Levels
(Chapters 4 and 10).
Condition: The relative ability of an aquatic resource to support and maintain a commu-
nity of organisms having a species composition, diversity and functional organization
comparable to reference aquatic resources in the region (Chapter 2).
Compensatory Mitigation: The restoration (re-establishment or rehabilitation), estab-
lishment (creation), enhancement and/or, in certain circumstances, preservation of
aquatic resources for the purpose of offsetting unavoidable adverse impacts that remain
after all appropriate and practicable avoidance and minimization has been achieved
(Chapters 2 and 11).
Credit: A unit of measure representing the accrual or attainment of aquatic functions at a
compensatory mitigation site. The measure of aquatic resource functions is based on the
resources restored, established, enhanced or preserved (Chapters 2 and 11).
Credit Production: The number of credits should reflect the difference between pre- and
post-compensatory mitigation project site conditions, as determined by a functional
assessment or other suitable method (Chapters 2 and 11).
Debit: A unit of measure representing the loss of aquatic functions at an impact or project
site. The measure of aquatic resource functions is based on the resources impacted by the
authorized activity (Chapters 2 and 11).
Determination of Credits: A description of the number of credits to be provided, which
includes a brief explanation of the rationale for this determination (Chapters 2 and 11).
Enhancement: The manipulation of the physical, chemical or biological characteristics
of an aquatic resource to heighten, intensify or improve a specific aquatic resource
function(s). Enhancement results in the gain of selected aquatic resource function(s), but
may also lead to a decline in other aquatic resource function(s). Enhancement does not
result in a gain in an aquatic resource area (Chapters 2, 4 and 11).
Functions: The physical, chemical and biological processes that occur in ecosystems.
A Function-Based Framework » May 2012
-------
Glossary of Terms
Function-Based Parameters: Parameters that are used to quantify or describe the
functional statement provided in the broad-level view of the Stream Functions Pyramid.
They can be a structural type of parameter that describes a stream condition at a point in
time, or they can be an actual function expressed as a rate that directly relates to a stream
process (Chapter 4).
Functional Capacity: The degree to which an area of aquatic resource performs a
specific function (Chapter 2).
Functional Category: The term for each level of the Stream Functions Pyramid, which
includes five levels: Hydrology (Level 1), Hydraulics (Level 2), Geomorphology (Level 3),
Physicochemical (Level 4), and Biology (Level 5) (Chapter 4).
Functional Statement: The statement that describes the functions for each Functional
Category, e.g., the transport of water from the watershed to the channel for Level 1
(Chapter 4).
Geomorphology Function: Level 3 functions on the Stream Functions Pyramid that
involve transport of wood and sediment within the channel to create diverse bed forms
and dynamic equilibrium (Chapters 4 and 8).
Hydraulic Function: Level 2 functions on the Stream Functions Pyramid that involve trans-
port of water in the channel, through sediments, and on the floodplain (Chapters 4 and 7).
Hydrology Function: Functions at the base of the Stream Functions Pyramid (Level 1)
that involve the transport of water from the watershed to the channel (Chapter 6).
Impact: An adverse affect.
Interagency Review Team (IRT): An interagency group of federal, tribal, state and/or
local regulatory and resource agency representatives that reviews documentation for, and
advises the district engineer on, the establishment and management of a mitigation bank
or in-lieu fee program.
Measurement Methods: A wide range of tools, techniques, metrics and assessment
approaches that qualify or quantify the Function-Based Parameters. Each measurement
method is assigned a category for Type, Level of Effort, Level of Complexity, and whether
it is a Direct or Indirect measure. Refer to Chapter 4 and Appendix Ac for a comprehen-
sive list of the measurement methods and their assigned categories.
Mitigation Rule: The 2008 Federal Compensatory Mitigation Rule administered by the
US Corps of Engineers and the US Environmental Protection Agency (33 CFR Parts 325
and 332; 40 CFR Part 230).
A Function-Based Framework » May 2012
-------
Glossary of Terms
Performance Standards: Observable or measurable physical (including hydrological),
chemical and/or biological attributes that are used to determine if the compensatory miti-
gation project meets its objectives.
Physicochemical Function: Level 4 functions on the Stream Functions Pyramid that
involve water quality associated with the Biology Function, including water chemistry,
nutrients and organic matter (Chapters 4 and 9).
Reference Aquatic Resource: A set of aquatic resources that represents the full range of
variability exhibited by a regional class of aquatic resources as a result of natural process-
es and anthropogenic disturbances (Chapter 2).
Reference Condition: A contextual background against which the degree of degrada-
tion, range of condition, and benefits of restoration can be measured.
Reference Reach: A term often used in Natural Channel Design for developing dimen-
sionless ratios to assess channel dimension, pattern and profile.
Restoration: The manipulation of the physical, chemical and biological characteristics
of a site with the goal of returning natural/historic functions to a former or degraded
aquatic resource.
Restoration Priority Levels: Also referred to as the Rosgen Priority Levels of Restoration.
Includes four restoration approaches for restoring incised channels (Chapters 3 and 11).
Riparian Areas: Lands adjacent to streams, rivers, lakes and estuarine shorelines that provide
a variety of ecological functions and services and help improve or maintain water quality.
Service Area: The geographic area within which impacts can be mitigated at a specific
mitigation bank or an in-lieu fee program.
Stream Functions Pyramid: The hierarchical representation of stream functions with
five levels: Hydrology, Hydraulics, Geomorphology, Physicochemical and Biology.
Stream Functions Pyramid Framework: The four components of the Stream Functions
Pyramid. First, broad-level view shows the five functional categories (Levels) with the
underlying controlling variables of geology and climate. Second, function-based param-
eters are provided for each functional category. Third, measurement methods are pro-
vided for each function-based parameter. And fourth, where possible, performance
standards are provided for the measurement methods.
A Function-Based Framework » May 2012
-------
EXECUTIVE SUMMARY
Stream restoration efforts have increased significantly in the US over the past few
decades and are now recognized as a billion-dollar industry. These restoration efforts
stem from centuries of abuse as humans continue to alter the riverine landscape for a
variety of purposes, including farming, logging, mining and development on the flood-
plain, and the subsequent need for channelization and flood control. These activities have
significantly diminished the natural functions of our stream corridors.
Today stream corridor restoration efforts seek to improve or restore these lost func-
tions. A variety of federal, state and local programs, along with efforts from non-profit
organizations, provide funding for these programs. The goals are varied and range from
simple streambank stabilization projects to watershed scale restoration. For these projects
to be successful it is important to know why the project is being completed and what
techniques are best suited to restore the lost functions. Knowing why a project is need-
ed requires some form of functional assessment followed by clear project goals.
To successfully restore stream functions, it is necessary to understand how
these different functions work together and which restoration techniques influ-
ence a given function. It is also imperative to understand that stream functions
are interrelated and build on each other in a specific order, a functional hierar-
chy. If this hierarchy is understood, it is easier to establish project goals. And
with clearer goals, it is easier to evaluate project success.
A large amount of funding for stream restoration is related to compensatory mitigation
required as part of Clean Water Act ( FWPCA, 1972) Section 404 permits issued by the
US Army Corps of Engineers (USACE). As part of a 404 permit authorizing impacts to
streams in one location, the 404 permit may require the permittee to conduct stream
restoration or enhancement activities in a nearby stream to compensate or offset the loss
of stream functions at the permitted impact site. The 2008 Federal Mitigation Rule
recommends that a functional or condition assessment be completed at the impact site to
quantify ecological losses (debits) and at the mitigation site to quantify projected ecologi-
cal gains (credits), which would be realized if the mitigation project is successfully imple-
mented (33 CFR 332.3(f)(l), 2008). Credits generated at the mitigation site should offset
the debits estimated at the impact site. Success criteria and performance standards are
required to measure mitigation project success and ensure that mitigation projects do
indeed generate the amount of credits initially projected.
Interagency Review Teams (IRTs) associated with each USACE District can provide
valuable support in the effective implementation of the 2008 Mitigation Rule, including the
development of region-specific Standard Operating Procedures (SOPs) designed to aid in
assessing debits and credits. However, the science of stream assessment is complex and the
practice of stream restoration is relatively young and rapidly evolving. Additionally, many
IRT staff have a stronger background in wetland science than fluvial geomorphology or
stream ecology, making the development of effective SOPs a significant challenge for IRTs.
A Function-Based Framework » May 2012 8
-------
Executive Summary
Document Goals
In order to address the central stream restoration issues delineated above, this docu-
ment presents three primary goals:
1. Help the restoration community understand that stream functions are inter-
related and generally build on each other in a specific order, a functional hierar-
chy, and understand that parameters can be used to assess those functions even
if some parameters are functions and others are structural measures.
This goal is addressed in the document in several ways. First, an overview of water-
shed and stream corridor processes is provided in Chapter 3. This chapter describes the
basic interplay of processes that work together in order for the watershed and stream
corridor to function; it serves as a watershed science "refresher" and includes references to
other sources for a deeper understanding of how watersheds work. Also provided in this
chapter is the background science necessary to understand the Stream Functions Pyramid
Framework that is presented in Chapter 4 and fully described throughout the remainder
of the document. The Stream Functions Pyramid Framework illustrates the hierarchy of
stream functions and provides a list of function-based parameters and measurement
methods that can be used to describe the functions. Performance standards are also
provided for each measurement method, when available.
2. Place reach scale restoration projects into watershed context and recognize
that site selection is as important as the reach scale activities themselves.
The importance of site selection is discussed in several places throughout the document,
including in Chapters 3 and 11. Site selection is a critical part of a stream restoration
project, especially if the goal is to provide physicochemical and/or biological improvements.
This step can make the difference between a successful and an unsuccessful project.
3. Provide informal guidance and ideas on how SOPs might incorporate stream
functions into debit/credit determination methods, function-based assessments
and performance standards.
This is a core element of the document. Chapter 11 provides examples of how the
Stream Functions Pyramid can be used to develop these parts of the SOP. Chapters 6
through 10 provide detailed information about the relative importance of each function-based
parameter, their measurement method and performance standard, where applicable.
This document is not a stand-alone stream assessment method, list of performance standards or
mitigation SOP, and in no cases should all of the measures or example performance standards be
used on a single project. In addition, there may be special projects that require parameters, measure-
ment methods and performance standards that are not included in this framework; it is not all-inclu-
sive. As discussed in each chapter, many of the measures are only appropriate in certain stream types
or landscape positions, and often multiple measures of the same function are reviewed. Practitioners
should take care to ensure the measures used are appropriate for the stream type, fully capture the
existing condition and can accurately measure achievement of the goals of the project.
A Function-Based Framework » May 2012
-------
Executive Summary
Stream Functions Pyramid Framework
The Framework used in this document was inspired by Fischenich (2006), where the
USAGE and a group of scientists and practitioners developed functional objectives for
stream restoration projects. This document uses different terminology than the Fisch-
enich (2006) document in an attempt to tie stream functions to common parameters that
can be used to describe functions. This document does not delineate between parameters
that are functions versus those that are structural measures. Rather, the parameters are
called function-based because each parameter can be used to help understand the overall
function for a given category, which is described below. Stream functions are separated
into a hierarchy of categories, ranging from Level 1 to Level 5 and include:
• Hydrology (Level 1)
• Hydraulic (Level 2)
• Geomorphology (Level 3)
• Physicochemical (Level 4)
• Biology (Level 5)
Within this hierarchical Framework, higher-level functions are supported by lower-
level functions, like a pyramid. For example, Hydraulic functions cannot occur without
Hydrologic functions, and so on. Chapter 4 describes each level in detail, and the full
Pyramid Framework synopsis, including measurement methods and performance stan-
dards, is provided in Appendix A.
BIOLOGY »
Biodiversity and the life histories of aquatic and riparian life
HYDRAULIC »
Transport of water in the channel, on the floodplain, and through sediments
A Function-Based Framework » May 2012
10
-------
Executive Summary
Social and recreational functions and values like fishing or boating are not included in
this document, and the hierarchy of functions is not all-inclusive. There are many other
parameters that can be assessed in order to describe a given function. However, this
document provides a structure and organization that can easily be adapted to fit individu-
al project goals and environmental settings. Since the lower-level functions of Hydrology,
Hydraulics and Geomorphology are required before Physicochemical and Biology func-
tions can be realized, this document places more focus on the lower-level functions. In
addition, these lower-level foundational functions have traditionally been addressed more
in stream restoration designs.
Stream Functions Pyramid Application
Chapter 11 provides detailed information about how the Pyramid can be applied. But
in general, there are three main areas where the Pyramid can provide guidance: setting
project goals and objectives, developing/reviewing specific function-based stream assess-
ment methods, and creating SOPs for stream mitigation programs.
Setting Project Goals and Objectives
A common stream restoration goal that is often stated in stream mitigation plans is the
improvement of channel dimension, pattern and profile so that the channel does not
aggrade or degrade. This goal primarily addresses channel stability. The Pyramid can be
used to develop goals that more directly relate to the improvement of functions. Well-
conceived goals should help answer the question, "Why is this project being pursued and
what functional improvements are being targeted?" Once a goal has been established, the
Pyramid can be used to develop objectives that call out which parameters, measurement
methods, or even performance standards will be used to evaluate the functional improve-
ment. In addition, once function-based goals and objectives have been selected and
identified within a certain level, the Pyramid can be used to determine which supporting
functions (lower levels) also need to be addressed.
Developing Function-based Stream Assessment Methods
Although it is not a functional assessment methodology, the Pyramid is a Framework
that can be used to create functional assessments or at least function-based assessments.
Using the Pyramid as a guide for developing function-based stream assessments will help
ensure that a protocol addresses parameters in the correct order based on function. These
assessment methodologies should include parameters from each level as it applies to site
and/or regional conditions and constraints. In addition, simple parameters may be select-
ed for rapid-based assessments, and more time-intensive parameters may be selected for
more complex studies. Parameters could also be selected to show functional gain or
improvement at a restoration or mitigation site, or functional loss at a proposed impact
site. Somerville (2010) provides a good overview of existing function-based assessments,
including their strengths and weaknesses.
A Function-Based Framework » May 2012 11
-------
Executive Summary
Creating SOPs for Stream Mitigation Programs
The Pyramid can also be used by Interagency Review Teams (IRTs) to develop debit
and credit determination methods and performance standards for stream mitigation
projects. In addition, if reference reaches are also assessed using a function-based ap-
proach, the functional capacity of the mitigation site can be addressed. This will help
IRTs to move away from attaching credits to restoring dimension, pattern and profile,
and move toward changes in parameters that describe or are themselves functions.
Example templates are provided in Chapter 11 to give IRTs ideas about how to create
function-based debit/credit determination methods. Additional case studies representing
a variety of scenarios are also provided in Appendix B. These example templates and case
studies are truly meant to be examples and are not a policy recommendation. They
should be considered "food for thought" as each IRT develops an SOP that fits their
region.
Understanding the functional hierarchy of stream restoration is vital to our nation's
efforts to reclaim and restore its riverine landscapes. This document is meant to become
a comprehensive resource for the public, private and non-profit organizations and agen-
cies whose goals include stream restoration. The hope is that when this hierarchy (the
Stream Functions Pyramid) is fully comprehended, embraced and applied, the efforts to
restore our nation's streams will become more focused, precise...and successful.
A Function-Based Framework » May 2012 12
-------
Chapter 1
Introduction
Stream restoration efforts have increased significantly in the US over the past few
decades and are now recognized as a billion-dollar industry (Bernhardt et al.; 2005).
These restoration efforts stem from centuries of abuse as humans continue to alter the
riverine landscape for a variety of purposes, including farming, logging, mining and
development on the floodplain with its subsequent need for channelization and flood
control. These activities have significantly diminished the natural functions of our stream
corridors (Wohl, 2004).
Today stream corridor restoration efforts seek to improve or restore these lost func-
tions. A variety of federal, state and local programs, along with efforts from non-profit
organizations, provide funding for restoration efforts. The goals are varied and range
from simple streambank stabilization to watershed scale restoration. Stream/wetland
mitigation for permitted impacts to aquatic resources also contributes to a large portion
of the overall restoration effort. For these projects to be successful, it is important to
know why the project is being completed and what techniques are best suited to restore the
lost functions. Knowing why a project is needed requires some form of functional assess-
ment to determine the nature and magnitude of the impairment, followed by clear
project goals designed to best address the impairment. To successfully restore stream
functions, it is necessary to understand how these different functions work together and
which restoration techniques influence a given function.
It is also important to know that stream functions are interrelated and build on each
other in a specific order, a functional hierarchy. If this hierarchy is understood, it is easier
to establish project goals. And with clearer goals, it is easier to evaluate project success.
One goal of this document is to help the restoration community understand that
stream functions occur in a general order, and that parameters can be used to
assess those functions even if some parameters are functions and others are
structural measures. Functions should be addressed in the order shown to have
a successful project. Another goal is to place reach scale restoration projects
into a watershed context and recognize that site selection is as important, if not
more important, than the reach scale activities themselves.
A large amount of funding for stream restoration is related to compensatory mitigation
required as part of Clean Water Act Section 404 permits issued by the US Army Corps of
Engineers (USACE). As part of a 404 permit authorizing impacts to streams in one
location, the 404 permit may require the permittee to conduct stream restoration or
enhancement activities in a nearby stream to compensate or offset the loss of stream
functions at the permitted impact site. The 2008 Federal Mitigation Rule recommends
A Function-Based Framework » May 2012
13
-------
Chapter 1: Introduction
that a functional or condition assessment be completed at the impact site to quantify
ecological losses (debits) and at the mitigation site to quantify projected ecological gains
(credits), which would be realized if the mitigation project is successfully implemented
(33 CFR 332.3(f)(l); 2008). Credits generated at the mitigation site should offset the
debits estimated at the impact site. Success criteria and performance standards are re-
quired to measure mitigation project success and ensure that mitigation projects do
indeed generate the amount of credits necessary to offset permitted impacts.
Interagency Review Teams (IRTs) associated with each USAGE District can provide
valuable support in the effective implementation of the 2008 Mitigation Rule, including
the development of region-specific Standard Operating Procedures (SOPs) designed to aid
in assessing debits and credits. However, the science of stream assessment is complex and
the practice of stream restoration is relatively young and rapidly evolving. Additionally, many
IRT staff have a stronger background in wetland science than fluvial geomorphology or
stream ecology, making the development of effective SOPs a significant challenge for IRTs.
Consequently, another goal of this document is to provide recommendations
and ideas on how SOPs might incorporate stream functions into debit/credit
determination methods, function-based assessments and performance standards.
1.1 » DOCUMENT OVERVIEW
The document is organized as follows:
Chapter 2: Overview of Federal Compensatory Mitigation Regulations: This
chapter provides a brief overview of the 2008 Federal Compensatory Mitigation Rule and
how this document supports the implementation of this Mitigation Rule. This chapter
may be helpful to those who are not familiar with stream mitigation and its associated
terminology.
Chapter 3: Watershed and River Corridor Processes: This chapter describes the basic
interplay of processes that work together for the watershed and stream corridor to func-
tion; it serves as a watershed science "refresher" and includes references to other sources
for a deeper understanding of how watersheds work, as well as provides the background
science necessary to understand the Stream Functions Pyramid and Framework described
in Chapter 4.
Chapter 4: The Stream Functions Pyramid: This chapter provides a detailed overview
of the Framework used in this document to assess stream functions. This Framework,
called the Stream Functions Pyramid Framework, describes the proposed hierarchy of
stream functions and provides a list of function-based parameters, measurement methods
and performance standards that can be used to describe the functions. It is important to read
this chapter before proceeding to the Hydrology through Biology chapters (Chapters 6 through 10).
Chapter 5: Reference Streams: This chapter provides an overview of how reference
stream reaches are used in natural channel design, stream assessments and stream mitiga-
A Function-Based Framework » May 2012 14
-------
Chapter 1: Introduction
tion. An introduction section provides a discussion about why a reference reach is impor-
tant and the different ways it can be used. Information is also provided about how to
select a reference reach based on project goals and objectives. A variety of existing field
assessment and data analysis methods are provided.
Chapters 6-10: Hydrology, Hydraulic, Geomorphology, Physicochemical and Biology —
These five chapters provide detailed information about the relative importance of each
function-based parameter, their measurement methods and performance standards,
where applicable. Some parameters and measurement methods do not have performance
standards, but instead have design standards. Design standard sections are included for
those parameters that are critical for understanding stream processes but are not appro-
priate for performance standards (typically because the research does not currently support
a standard, and sometimes because the parameter is too variable or too site specific).
Sediment transport competency and capacity are examples of parameters that include a
section on design standards but not performance standards. These chapters represent the
bulk of the document and are intended to serve as a reference or guide for those who are
developing function-based assessments, restoration goals or performance standards.
Chapter 11: Applications — This chapter shows how the Stream Functions Pyramid can
be used to help develop stream restoration goals, function-based assessments and debit/
credit determination methods for stream mitigation SOPs. Examples of each are provided.
For the SOP example, different scenarios are provided that represent the bulk of stream
impacts and restoration needs from across the country.
It should be noted that this document is not a stand-alone stream assessment
method, list of performance standards or mitigation SOP, and it is not necessary
or recommended to apply all of the measures or example performance stan-
dards for a single project. In addition, there may be important parameters that are not
included, especially for rare or unique settings. As discussed in each chapter, many of the
measures are only appropriate in certain stream types, environmental settings, climates
or landscape positions, and often multiple measures of the same parameter are provided.
In addition, actual stream assessments may utilize a combination of parameters to
determine an overall functional score, something that this document does not provide.
Practitioners should take care to ensure the measures used are appropriate for the stream
type, fully capture the existing condition, and can accurately measure achievement of the
project goals.
1.2 » WHAT THE DOCUMENT DOES AND DOES NOT PROVIDE
This document does provide:
• An overview of watershed and riverine processes.
• A hierarchical framework illustrating the relative relationship of stream functions and
parameters that can be used to describe those functions. The hierarchical Framework,
A Function-Based Framework » May 2012 15
-------
Chapter 1: Introduction
called the Stream Functions Pyramid, shows that functions build on each other in a
general order and that physical functions — like the transport of water and sediment
— support physicochemical and biological functions. Parameters include structural and
functional measures, which together are considered to be function-based. Most
importantly, the hierarchy provides a logical framework of parameters that practitio-
ners can use to evaluate stream functions.
• The state of the science and tools to help create function-based goals, assessment
methods, debit/credit determination methods and performance standards.
• Examples of how the Stream Functions Pyramid can be applied to setting project
goals and objectives, developing specific function-based stream assessment methods,
and creating debit/credit determination methods for stream mitigation programs.
• References to key textbooks, peer-reviewed papers and websites for more
in-depth information.
This document does not provide:
• A Standard Operating Procedure for stream assessments and mitigation.
• Stream debit and credit formulas. However, IRTs can use select parameters and their
corresponding methods of measurement and performance standards as a guide for cre-
ating formulas for their region.
• A specific functional assessment methodology.
• A specific monitoring approach.
• Even though the Framework includes a wide range of parameters that can be used to
describe functions in their respective category, the document does not promote using
all of these parameters in a given assessment or restoration project. The same is true
for the measurement methods. A variety of measurement methods are provided for
each parameter. Rather than use all of the measurement methods for a given param-
eter, the user should pick the best methods given the project goals and budget.
• A manual or textbook on fluvial processes and stream assessment. However, refer-
ences are provided that cover a wide range of stream processes and functions.
• Function-based parameters in this document are not all-inclusive. Other function-
based parameters, measurement methods and performance standards may exist that
are more suitable based on project objectives.
1.3 » PROJECT PARTNERSHIPS
The development of this document is through a partnership between the US Fish and
Wildlife Service (FWS) and US Environmental Protection Agency (EPA). The FWS and
EPA entered into a partnership in 2006 to develop and provide standardized tools and
training modules on how to evaluate stream assessments and restoration designs. The
FWS and EPA recognized the need for these tools and training modules to improve the
link between stream restoration and compensatory mitigation under Section 404 of the
Clean Water Act. Additionally, such tools and training modules are relevant to a suite of
state, local and federal natural resource agencies that are regularly tasked with reviewing
A Function-Based Framework » May 2012 16
-------
Chapter 1: Introduction
the merits of stream restoration, enhancement and/or protection projects proposed as
restoration, or to compensate for authorized impacts to streams.
The first stream tool and training module developed under this agreement was the
Natural Channel Design Review Checklist. The Checklist provides guidance on important
factors to consider when reviewing natural channel designs. It is intended to provide the
reviewer with a rapid method for determining whether a project design contains an
appropriate level of information. The Checklist consists of a list of questions that must be
answered as part of a design review and includes the following sections: Watershed and
Geomorphic Assessment, Preliminary Design, Final Design, and Maintenance and
Monitoring Plans. The training module uses a 3.5-day training course and includes an
overview of stream processes, channel stability and function, restoration potential, and
natural channel design techniques.
More information on offerings of the trainings can be found at training.fws.gov and
www.stream-mechanics.com. The Natural Channel Design Review Checklist and other stream
mitigation resources can be found on EPA's website for compensatory mitigation under
the "Technical Resources for Stream Mitigation" section: water.epa.gov/lawsregs/guidance/
wetlands/wetlandsmitigationjndex.cfm.
A Function-Based Framework » May 2012 17
-------
3.QG iniGniioricuiy LGTI t5i3.riK
A Function-Based Framework » May 2012 18
-------
Chapter 2
Overview of Federal Compensatory Mitigation Regulations
2.1 » OVERVIEW
Since a major goal of this document is to provide IRTs with tools that can be used to
develop Standard Operating Procedures (SOPs), a brief background is provided on the
Federal Mitigation Regulations as it pertains to credit determination methods, functional
assessments and performance standards. This overview is provided for informational
purposes only and should not be considered an official source of regulatory information.
The interpretations are those of the authors and do not necessarily represent the views of
the EPA or the USAGE.
In April 2008 the USAGE and the EPA jointly issued new regulations clarifying com-
pensatory mitigation requirements for Department of the Army permits (33 C.F.R. §
332/40 C.F.R. § 230). The 2008 Mitigation Rule was designed to improve the planning,
implementation and management of compensatory mitigation projects. It emphasizes a
watershed approach in selecting compensatory mitigation project locations, requires
measurable performance standards, requires regular monitoring for all types of compen-
sation, and specifies the components of a complete compensatory mitigation plan. This
plan includes assurances for long-term protection of compensation sites, financial assur-
ances, and identification of parties responsible for specific project tasks. The 2008 Mitiga-
tion Rule also applies equivalent standards to the three mechanisms for providing com-
pensatory mitigation: permittee-responsible compensatory mitigation, mitigation banks
and in-lieu fee mitigation.
While traditional approaches to determining the appropriate amount of compensation
involved reliance on measures of acres or linear feet, the USAGE and EPA explicitly stated
in the preamble to the Final Rule that, "With this rule, we are encouraging the use of functional
and condition assessments to determine the appropriate amount of compensatory mitigation needed to
offset authorized impacts, instead of relying primarily on surrogate measures such as acres and linear
feet. In the future, there will be more assessment methods available to quantify impacts and compen-
satory mitigation." (FR Vol 73, 19633) The Rule recognizes that science-based rapid function
or condition assessment methodologies provide a more objective, systematic and reliable
approach to characterize and quantify the expected aquatic resource losses or debits at
impact sites, as well as the potential aquatic resource gains or credits at compensatory
mitigation sites.
To ensure that functional gains have indeed occurred at a mitigation site, the permittee
(or mitigation provider in the case of mitigation banks or in-lieu fee programs) must meet
a set of ecological performance standards tailored to its specific compensation project.
A Function-Based Framework » May 2012
19
-------
Chapter 2: Overview of Federal Compensatory Mitigation Regulations
The 2008 Mitigation Rule requires that these performance standards be based on the best
available science that can be measured or assessed in a practicable manner. The rule states
that performance standards must be based on attributes that are objective and verifiable,
which may include variables or measures of functional capacity from the following:
• Functional assessment methodologies,
• Measurements of aquatic resource structural characteristics, and/or
• Comparisons to reference aquatic resources of similar type and landscape position.
Implementation of effective performance standards provides the USAGE, other mem-
bers of the IRT and other regulatory agencies with observable and measurable parameters
to ensure that compensatory mitigation is meeting its objectives. To ensure that perfor-
mance standards are met, a project's mitigation plan must also include mechanisms to
provide adequate monitoring, maintenance strategies and long-term stewardship.
2.2 » RESOURCES
The EPA provides stream and wetland mitigation resources on their website (water.epa.
gov/lawsregs/guidance/wetlands/wetlandsmitigation_index.cfm). The Federal Mitigation
Regulations can be downloaded from this website along with a wealth of additional
information, including fact sheets, guidance manuals, training resources and technical
resources. Terms from the regulations are used throughout this document, and their
definitions are provided in the glossary.
A Function-Based Framework » May 2012 20
-------
Chapter 3
Watershed and River Corridor Processes
3.1 » WATERSHED PROCESSES
Streams and rivers are integral parts of the landscape, carrying water and sediment
from higher elevations to downstream lakes, estuaries and oceans. Along the way, they
provide life-giving water to a wide array of ecosystems, including wetlands, bogs, ponds,
forests and floodplains.
The land area draining to a stream or river is called its watershed. When rain falls in a
watershed, it runs off the land surface, infiltrates the soil or evaporates, forming the
fundamental components of the hydrologic cycle (Figure 3.1). From the standpoint of
stream formation, the greatest concern is with the hydrologic processes of runoff and
infiltration. Surface runoff, whereby excess water collects on the ground surface and
flows over land toward watershed valleys and stream systems, is produced when rainfall
exceeds the rate at which water can infiltrate the soil. Surface runoff is the process by
which stream levels rise and fall during and following rainfall events.
In most systems, a large portion of the water that infiltrates the soil also reaches the
stream system, but by sub-surface or groundwater flow. This process occurs much more
slowly and steadily than surface runoff. Groundwater discharge is the main source of
water that produces baseflow conditions in stream channels.
The hydrologic processes (precipitation, infiltration, runoff, evaporation) that occur at
the watershed level influence the character and functions of streams. Small stream
channels form at the higher elevations, or headwater regions, of a watershed and become
progressively larger in size as the watershed size increases (i.e., moving downstream). In
the headwater regions of a watershed, surface runoff concentrates and moves downhill,
forming small ephemeral channels and gullies. Ephemeral channels carry only surface
runoff and thus flow only for short periods of time (generally less than 24 hours) follow-
ing rainfall events. Moving down the watershed, ephemeral channels carry more and
more water and become intermittent channels, which carry water for extended periods
following rainfall events and during wet seasons. Intermittent channels carry surface
runoff but also receive discharge from shallow groundwater, particularly during wet
portions of the year. Farther downstream, intermittent channels give way to perennial
channels, which generally flow year round. Perennial channels carry not only surface
runoff, but also groundwater discharge that maintains baseflow conditions in the stream.
During drought periods, groundwater levels can drop, and even perennial stream chan-
nels can stop flowing for periods of time. But in general, perennial channels maintain
some permanent water level that sustains aquatic life and provides the functions that are
A Function-Based Framework » May 2012
21
-------
Chapter 3: Watershed and River Corridor Processes
most associated with creeks and rivers. (For more information on the hydrologic cycle
and its role in the development of streams, see Stream Corridor Restoration: Principles, Pro-
cesses and Practices (FISRWG, 1998) www.nrcs.usda.gov/technical/stream_restoration.)
A stream and its watershed comprise a dynamic balance where the floodplain, channel
and stream bed evolve through natural processes that erode, transport, sort and deposit
sediments. Land-use changes in the watershed, channel straightening, culverts, removal
of streambank vegetation, impoundments and other activities can upset this balance. As
a result, adjustments in channel form often occur with changes in the watershed. A new
equilibrium may eventually result, but not before the associated aquatic and terrestrial
environment are altered, often severely. By understanding the processes that occur at the
watershed scale, the role and function of the river is better understood, and proper deci-
sions for its care and protection can be made.
FIGURE 3.1 THE HYDROLOGIC CYCLE
HAIN LLUUUb
**
Source: Adapted from FISRWG (1998)
A Function-Based Framework » May 2012
22
-------
Chapter 3: Watershed and River Corridor Processes
3.2 » RIVER CORRIDOR PROCESSES
River Form and Function
The interaction of streamflow with the banks and bed produces a wide variety of
stream channel forms (Knighton, 1998). Though streams and rivers vary in size, shape,
slope and bed materials, all streams share common characteristics and functions. Streams
have banks and beds consisting of mixtures of substrate (i.e., cobble, gravel, sand or silt/
clay) that usually differ from the surrounding floodplain soils. Other physical characteris-
tics shared by some stream types include pools, riffles, steps, point bars, meanders,
floodplains and terraces. All of these stream characteristics collectively describe the
river's form and are driven by the interactions between climate, geology, topography,
vegetation and land use changes in the watershed.
Stable streams in wide valleys migrate across the landscape slowly over geologic time,
while maintaining their overall form and function. Naturally stable streams must be able
to transport the sediment load supplied by their watershed. Instability occurs when
scouring causes the channel bed to erode (degrade), or excessive deposition causes the
channel bed to rise (aggrade). Often, instability results from changes in the watershed.
For example, stream degradation can result from urbanization influences. During storm
events, increased impervious surfaces in a watershed produce greater runoff amounts,
and stream flooding frequency and intensity also increase, leading to excessive stream
bed scour and degradation. Stream aggradation can result from poor land-use practices
that lead to excess sediment in runoff reaching the stream, increasing the sediment load
of a stream above that which it can adequately transport.
A generalized relationship of stream stability is shown as a schematic drawing in
Figure 3.2, often referred to as Lane's Diagram (Lane, 1955). The drawing illustrates that
sediment size and load is proportional to channel slope and discharge. A change in any
one of these variables can cause a physical adjustment in the stream channel form. There-
fore, channel form characteristics and changes in channel form over time are often used
to assess channel stability and whether the channel is in equilibrium with its watershed.
The most commonly used parameters to describe and quantify channel form are dimen-
sion, pattern and profile, each of which is described below.
3.3 » CHANNEL FORM
Channel Dimension
The dimension of a stream refers to the cross-sectional shape of the channel and
includes such parameters as width, depth, bank height, hydraulic radius, etc. The width
of a stream generally increases in the downstream direction in proportion to the square
root of discharge. The width and depth of a stream are also influenced by discharge
(occurrence and magnitude), the sediment the stream transports (size and type), stream
bank vegetation, and the stream bed and bank materials. For example, in the humid,
Southeastern portions of the US, stream channels tend to have narrow widths and deeper
depths due to dense vegetation and cohesive floodplain soils. In the arid to semi-arid
A Function-Based Framework » May 2012 23
-------
Chapter 3: Watershed and River Corridor Processes
Southwestern regions, stream channels tend to be much wider and shallower, with less
streambank vegetation and more erodible bank sediments.
FIGURE 3.2 LANE'S DIAGRAM
(Illustrating factors affecting channel degradation and aggradation)
Source: Graphic design by
Michael Baker Corporation
Channel Pattern
Stream pattern refers to the aerial view of a channel. Streams located in steep, narrow
valleys tend to be straighter and follow the alignment of the valley, whereas streams on
broad, flat floodplains tend to follow a more sinuous path. Quantitatively, stream pattern
can be defined by measuring sinuosity, meander wavelength, radius of curvature, ampli-
tude, and belt width (Figure 3.3). The sinuosity of a stream is defined as the channel
length divided by the valley length, which is measured along the direction of fall of the
valley. A meandering stream reach increases resistance and reduces channel gradient
relative to a straight reach. The geometry of the meander and spacing of riffles and pools
adjust so that the stream performs minimal work and balances its energy.
Channel Profile
The profile of a stream refers to its longitudinal slope. At the watershed scale, channel
slope generally decreases as you move downstream. The size of the bed material also
A Function-Based Framework » May 2012
24
-------
Chapter 3: Watershed and River Corridor Processes
FIGURE 3.3 PATTERN MEASUREMENTS OF A MEANDER BEND
MEANDER WAVELENGTH
FLOW
PC = Point of Curvature = point at which
the straight section of a riffle meets the
curved section of a meander bend.
PT = Point of Tangency = point at which
the curved section of a meander bend
meets the straight section of a riffle.
Source: Adapted from Rosgen (1996)
FIGURE 3.4 LONGITUDINALPROFILEOFASTREAM
RIFFLE
HIGH WATER SURFACE
LOW WATER SURFACE
O
RIFFLE
POOL
Source: Adapted from Knighton (1998)
POOL
A Function-Based Framework » May 2012
25
-------
Chapter 3: Watershed and River Corridor Processes
typically decreases in the downstream direction. Channel slope is inversely related to
sinuosity. This means that steep streams have low sinuosity and flat streams have high
sinuosity. The profile of the stream bed can be irregular because of variations in bed
material size and shape, riffle-pool spacing and other variables. The water surface profile
mimics the bed profile at low flows. As water rises in a channel during storms, the water
surface profile becomes more uniform (Figure 3.4).
3.4 » OVERVIEW OF STREAM FUNCTIONS
Streams carry the water supplied by their watershed. The resulting hydrology and
hydraulic processes provide the basic foundation for all other functions that streams
provide. The relationships between precipitation, runoff, infiltration and groundwater
flow determine the amount of water that the stream carries at any given time, the energy
of the water to move sediment, the physicochemical processes that affect water quality,
and the biological processes that the stream will support. Stream channels that are
connected with their floodplains attenuate flood pulses and spread nutrients and organic
matter during flooding events. Streamflows rise and fall with precipitation and snowmelt
events, resulting in the dynamic range of flows, which defines the channel form on
which many other processes and functions rely. Groundwater is both recharged and
discharged along stream channels, providing another hydrologic link between the stream
channel and the landscape.
At the interface between the stream channel and the soil surface lays the hyporheic
zone, a layer of sediment, soil and porous space where interchanges between streamflow
and groundwater occur. Water that moves from the stream into the hyporheic zone is
held for a longer retention time than normal streamflow. In addition, because of the
intermixing between nutrient rich groundwater and oxygen rich stream water, the
hyporheic zone is of critical importance to the chemical transformations that affect
nutrients and other compounds within stream systems.
The transport of water and sediment is reflected in the bed features that are formed
within a stream channel. Natural streams have sequences of riffles and pools or steps and
pools that maintain channel slope and stability (Figure 3.4). The riffle is a bed feature
that may have gravel or larger rock particles. The water depth is relatively shallow, and
the slope is steeper than the average slope of the channel. At low flows, water moves
faster over riffles, which removes fine sediments and provides oxygen to the stream.
Riffles enter and exit meanders and control the stream bed elevation. Pools are located on
the outside bends of meanders between riffles. The pool has a near-flat water surface
(very low slope) and is much deeper than the stream's average depth. At low flows, pools
are depositional features and riffles are scour features. At high flows, however, the pool
scours and the bed material deposits on the riffle. This occurs because a force applied to
the stream bed, called shear stress, increases with depth and slope. Depth and slope increase
rapidly over the pools during large storms, increasing shear stress and causing scour.
Stream channels, corridors and floodplains form a valuable ecosystem network. In
addition to transporting water and sediment, natural streams provide habitat for many
A Function-Based Framework » May 2012 26
-------
Chapter 3: Watershed and River Corridor Processes
aquatic organisms including fish, amphibians, aquatic insects, mollusks and plants.
Riffles and pools, and other bed features such as runs and glides, form a diversity of
aquatic habitats and provide the foundation for many of the biological and water quality
functions that streams provide. Macrobenthic organisms cling to rocks and coarse sub-
strates in riffle areas, filtering food from the flowing water and thriving on the oxygen-
rich water. Many fish species utilize meander pool areas due to the cover provided for
protection and ambush and for cooler water temperatures afforded by the deeper water
depth. Even within a single meander pool, there are aquatic organisms that prefer to live
at varying water depths and locations within the pool, illustrating the natural diversity
and biological functions that stream systems provide. The hyporheic zone also serves as a
habitat zone for certain aquatic species and microbial life that is especially suited for life
in this transition zone between groundwater and surface waters.
Trees and shrubs along the streambanks regulate water temperatures through shading
and provide organic matter to the system, which is stored and transported forming the
energy web that supports aquatic life and diversity. The processes of energy transfer in
streams are simplistically described by the river continuum concept (RCC). The RCC is a
generalization that is based on the idea that a watercourse is an open ecosystem in
constant interaction with the streambank and bed, and moving from source to mouth,
constantly changing (Gordon et al., 2004). Beginning in its headwaters, the energy
available to a river is highly influenced by the organic material that is delivered from its
watershed, or sources external to the stream itself. Moving downstream, the impact of
direct contributions of new material to the river becomes less important as the material
delivered from upstream continues to be processed and transformed, and primary pro-
duction within the river becomes a more dominant source of energy than external inputs
of organic matter. The RCC provides a theoretical model for visualizing the importance
that energy relationships have on biodiversity and chemical functions of a stream system.
Streams affect groundwater levels and the transfer of water and nutrients between
adjacent wetlands and riparian areas, supporting ecosystem diversity beyond the limits of
the stream channel itself. Riparian buffers along streams filter sediment and pollutants
from runoff, and promote uptake of nutrients and chemical reactions in the soil and
water column that improve water quality. Streams also provide recreational functions,
such as fishing, boating, swimming, wildlife viewing and green space.
All the functions described above relate back to the river's form and its relationship
with its watershed. For more information regarding the river's form and its relationship
to processes and functions, see Knighton (1998), Leopold et al., (1992) and Wohl (2004).
3.5 » AMERICAN RIVER REGIONS
North America supports a wide variety of river and stream systems, owing to the
wide range of climatic and geologic conditions across the continent. River systems of the
continent can be divided into six major regions, as proposed by Wohl (2004). Figure 3.5
shows the location of each of these regions, and a brief summary of each region (as
described by Wohl, 2004), is provided below. Wohl's river regions can be considered a
A Function-Based Framework » May 2012 27
-------
Chapter 3: Watershed and River Corridor Processes
broad delineation for North America. For more detailed information on major river basins
within North America and the functions they provide, see Rivers of North America, edited
by Benke and Gushing (2005).
FIGURE 3.5 RIVER REGIONS MAP OF NORTH AMERICA(Wohl, 2004)
Kuskok
ARCTIC
REGION
WESTERN
CORDILLERAN
REGION
LOWER
MISSISSIPPI
REGION
SOUTHWESTERN
CANYON REGION
NORTHEAST
AND EAST
CENTRAL
REGION
CENTRAL REGION
Source: Adapted from Wohl (2004)
A Function-Based Framework » May 2012
28
-------
Chapter 3: Watershed and River Corridor Processes
Arctic Region
The rivers in the Arctic Region drain north to the Arctic Ocean. Rivers of this region
are characterized by high sediment loads (in part from glacier melt and streambank
erosion due to freeze/thaw cycles) and ice flows, and often exhibit braided channel forms.
The Mackenzie and Yukon Rivers are the largest river drainages within the region. Streams
of the region support very little year-round aquatic species, but are host to some of the
largest yearly runs of anadromous fish species, such as salmon, anywhere in the world.
Western Cordilleran Region
The Western Cordilleran rivers drain primarily to the Pacific Ocean, although some
originate east of the continental divide and drain to the Atlantic Ocean. The region
stretches from southern California north to Alaska, and from the Pacific Ocean to rough-
ly the continental divide. Rivers of the region are diverse but are commonly characterized
as steep, mountain streams. Many of this region's rivers begin at their headwaters as
high-gradient, step-pool channels, where high sediment loads, debris flows and landslides
are common. Moving further down gradient, the rivers become large and meandering,
with moderate sediment loads and course substrates. Like the Arctic Region rivers, rivers
of the Western Cordilleran Region were once home to large populations of trout and
seasonal runs of salmon; however, degraded stream habitat, flow durations and water
quality in the region have reduced or eliminated many of these populations.
Central Region
Rivers of the Central Region are generally characterized as broad, shallow, meandering
river systems. Streams of the northern Central Region drain to Hudson Bay, while
streams of the central and lower portion of the region drain to the Mississippi River and
the Gulf of Mexico. Peak flows occur during spring and early summer, as a result of snow
melt and intense rains. Fine sediment loads are often high. The streams of the region are
very diverse biologically, supporting a wide range of fish and aquatic species.
Northeast and East-Central Region
The Northeast and East-Central Region rivers drain east to the Atlantic Ocean. The St.
Lawrence River drains the upper portion of the region. Along the central-Atlantic Coast,
a variety of rivers begin in the Appalachian Mountains, crossing the Piedmont and
Coastal Plain physiographic regions on their way to the Atlantic Ocean. Rivers of the
region mostly drain densely vegetated catchments, keeping sediment loads relatively low.
High flows typically occur in the fall and winter, with the exception of large tropical
systems that can drop large amounts of rainfall quickly and cause significant flooding
during the summer and early fall months. Rivers of this region, like those of the Lower
Mississippi Region, support the greatest species richness and highest number of endemic
species of any of the rivers in North America.
Lower Mississippi Region
Rivers of the Lower Mississippi Region drain to the Gulf of Mexico and originate in
A Function-Based Framework » May 2012 29
-------
Chapter 3: Watershed and River Corridor Processes
the southwestern portion of the Appalachian Mountains and the eastern edges of the
great interior plains. These rivers meander broadly over low-slope floodplains created by
long-term sediment deposition. Suspended sediment loads are often high, as commonly
observed with the lower Mississippi River. Rivers of this region have been highly ma-
nipulated with levees and channelization to decrease the threat of flooding and provide
more land for development. Species diversity is high throughout the region.
Southwestern Canyon Region
The Southwestern Canyon Region rivers and streams are characterized by deeply-
incised channels and canyon valleys that have downcut over geologic time to keep pace
with uplift of the Colorado Plateau by geologic forces. These streams flow through desert
lands, with the larger rivers being perennial streams that flow year-round, while many of
the smaller streams only flow for portions of the year. Suspended sediment loads are high
due to the highly erodible soils and sedimentary rocks of the region. Many of the native
fish species are endemic species that are limited to the Colorado River Basin.
3.6 » STREAM CLASSIFICATION
Stream classification is an important tool to communicate information about streams
using a common language. There have been many stream classification systems pub-
lished over the past century, beginning with Davis (1899) that classified streams in terms
of age (youthful, mature and old age). These classification systems use different ap-
proaches to categorize streams based on qualitative and quantitative assessment at
different spatial and temporal scales, e.g., Montgomery and Buffington (1993) developed a
stream classification system that is applicable to the Pacific Northwest region. For further
details about stream classification history, refer to Naiman et al. (1992) and Rosgen (1994).
In general, the most useful stream classification system should encompass a broad spatial
and temporal scale, integrate structural and functional characteristics under different
disturbance regimes, provide information about form and process mechanisms that
control stream features, and be easily applied by stream practitioners (Naiman et al.,
1992). For the purposes of this publication, the Rosgen (1994) stream classification system
will be referenced when describing stream types. This system can be applied consistently
over a large geographic area using quantitative descriptions. It has also been referenced by
many USACE Districts as part of the compensatory mitigation program (USACE Wilm-
ington District et al., 2003; USACE Savannah District, 2004; USACE Norfolk District and
VDEQ, 2007; and USACE Charleston District, 2010).
The specific objectives of the Rosgen stream classification system (Rosgen, 1996) include:
1. Predict a river's behavior from its appearance.
2. Develop specific hydraulic and sediment relationships for a given stream type.
3. Provide a mechanism to extrapolate site-specific data to stream reaches having similar
characteristics.
4. Provide a consistent frame of reference for communicating stream morphology and
condition among a variety of disciplines and interested parties.
A Function-Based Framework » May 2012 30
-------
Chapter 3: Watershed and River Corridor Processes
The Rosgen (1994) classification and assessment system consists of four levels (Levels I
through IV), ranging from broad qualitative descriptions to detailed quantitative assess-
ments (Figure 3.6). Level I and Level II are the predominant parts used to characterize the
stream. Level I is a broad geomorphic characterization that categorizes streams into eight
different stream types (A through G) using the integration of landform and fluvial fea-
tures of valley morphology with channel slope, pattern, profile and dimension. Level II is
called the morphological description and requires field measurements. The stream types
are divided into discrete slope ranges and dominant channel-material particle sizes,
which are given numbers 1 (bedrock) through 6 (silt/clay). Figure 3.7 presents a key for
the Rosgen system for Level I and Level II.
Details for Level III and Level IV are not provided in this publication but can be found
in Rosgen (1994; 1996). In general, Level III is an evaluation of stream condition and
stability that requires an assessment and prediction of channel erosion, riparian condition,
channel modification and other characteristics. Level IV is verification of predictions
made in Level III and consists of sediment transport, streamflow and stability measurements.
3.7 » WATERSHED AND STREAM RESTORATION
Watershed Scale Restoration
Many of the impairments present in today's rivers and streams are a result of processes
that occur at the watershed level. Poor sediment and erosion control practices lead to excess
fine sediments that are delivered to water courses. Increased urbanization and impervious
surfaces result in increased runoff during rainfall events, and higher peak streamflows
that cause erosion and stream down-cutting. Pollution, both from point sources and
non-point sources, enters streams and impairs water quality. To address these impair-
ments, improvements and restoration must be performed at a watershed scale.
"A watershed approach is the most effective framework to address today's water resource challenges.
Watersheds supply drinking water, provide recreation and respite, and sustain life. More than
$450 billion in food and fiber, manufactured goods, and tourism depends on clean water and
healthy watersheds."
-US Environmental Protection Agency
(water.epa.gov/type/watersheds/approach.cfm)
"We cannot save trout without saving their river and floodplain habitats. We cannot save river and
floodplain habitats — and the plants and insects of the trout's food web — if we do not also maintain
the processes controlling water and sediment entering the river corridor from the surrounding hillslopes
and uplands. They go hand in hand."
-Ellen Wohl, Disconnected Rivers, 2004
Emphasis on watershed-level restoration and water-quality improvements is increasing,
and the tools being used are also expanding. Over the past two decades, there have been
considerable interest and use of best management practices (BMPs) as a tool for address-
A Function-Based Framework » May 2012 31
-------
Chapter 3: Watershed and River Corridor Processes
FIGURE 3.6 THE HIERARCHY OF RIVER INVENTORY AND ASSESSMENT (Rosgen, 1996)
STRUCTURAL
CONTROLS.
LITHOLOGV
<^>
c
FLUVIAL
PROCESS
., fc MPOSITIONAL
MATERIALS
t
ENTRENCHMENT RATIO
WIDTH/DEPTH RATIO
SINUOSITY
t
RIPARIAN VEGETATION
DEPOSTION PATTERN
DEBRIS OCCURRENCE
MEANDER PATTERN
CHANNEL STABILITY RATING
...SEDIMENT SUPPLY
BED STABILITY
...W/D RATIO 'STATE'
^
SEDIMENT MEASUREMENTS
Bpdioad sediment
Suspended sediment
STREAMFLOW
MEASUREMENTS:
Hydrauiii s
Resistance
Hydrograplts
V
\
,'
,-
\
.
•
•'
0
0
0
0
o
GEOMORPHIC
CHARACTERIZATION
LEVEL 1
Stream Types
A through 'G'
J
o
^\
MORPHOLOGICAL
DESCRIPTION
LEVEL II
Stream Types
A1-AS througfi G1-G6
^ j
o
r ^v
STREAM "STATE" or
CONDITION
LEVEL III
^ ^J
o
f" "V
VALIDATION IEVEL
LEVEL IV
v ^
0
0
0
0
CHANNEL PATTERNS:
Single Thread
Multiple Thread
Anastomosed
Sinuosity
Meander Width Ratio
V J
^ -\
CHANNEL SLOPE
CHANNEL MATERIALS
L. J
f ^
BANK EROSION POTENTIAL
STREAM SIZE/ORDER
FLOW REGIME
ALTERED CHANNEL "STATE"
...DIMENSIONS
...PATTERNS
...SLOPE
...MATERIALS
V J
STABILITY
Aggrailliion/Etearadatton
SEDIMENT:
Change In Storage and
Size Distribution
Bank EroMoii Rates
Imbed dedneWDistribution
Time Trends-Stabtllly
V J
Source: Reproduced with permission from Wildland Hydrology
A Function-Based Framework » May 2012
32
-------
Chapter 3: Watershed and River Corridor Processes
FIGURE 3.7 KEYTO THE ROSGEN STREAM CLASSIFICATION OF NATURAL RIVERS
(Rosgen, 1996)
SlNGLC-THRtADCHMINBS
MULTIPLE CHANNELS
V V
EHiMichmenl
Balto
\' V
EHnKNCHEDZ2I
V V
WidlluDtplli
Ralto
LOW
Wk»WDef»hfciB
H
V.
'
V
V
[i
»-, .
LOW-HI
SmtiKil)
W£
^J
| SJopeRangc | | SlepeRany? | Slopa Barge | | Sfcpc ftmge | Stopa Range Stop?Range || Stay*
u.o:
Qffi-
o.ose | 0031
Bffi-
$ay,
KL- I^M««I fe«l
BEOBQCH
BXilt'CR'i
BU fb
0
ttrsam wchx, VIIUBI of inmic/unM ind
Fl gu r» 3. toy i o f» Rotggn C « n (I e «1 •. on of N«l u:« IR w« n As « function of ih« • continuum of pny ji cs I virtiMM' tmttn i n
itiunt)' rnioi cm vary by W- 0.2 uniU; wMli valuts for mfdlh/ilaplli iitloi can vir; by ,1- 2.0 unlti.
Source: Reproduced with permission from Wildland Hydrology
ing watershed health. Common BMP practices such as created wetlands, retention basins,
bioretention areas, infiltration areas and restoration of riparian buffers are but a few of
the practices that have been implemented to improve watershed health. These practices
generally seek to reduce the amount of runoff delivered to streams (detention), reduce the
rate at which runoff reaches streams (attenuation), increase the amount of water that
percolates into the soil (infiltration), and/or promote physical and chemical processes that
remove pollutants and sediment from runoff waters. Most of these practices are installed
on smaller headwater catchments of a watershed, where such approaches are more
feasible and cost effective, and where pollutants can be trapped near their sources.
River restoration is a technique that is applied at the stream reach scale and is gener-
ally used to complement the other techniques described above. BMP approaches can help
to improve the quality and timing of water entering a receiving stream; river restoration
approaches can address stability and water quality problems that are expressed or develop
in the river itself, such as channel incision, streambank erosion and loss of aquatic habitat.
A Function-Based Framework » May 2012
33
-------
Chapter 3: Watershed and River Corridor Processes
River Restoration
River or stream restoration has been defined in many different terms, but is generally
considered to describe a set of activities that help improve the environmental health of a
stream. Other terms commonly used for stream restoration include stream reclamation,
stream stabilization, natural channel design and channel rehabilitation. Depending on
the person using the term, stream restoration can have different meanings and associa-
tions, and can cover a wide range of practices and approaches to improving watercourses.
The practice of stream restoration began to achieve momentum in the 1980s, as inter-
est grew in addressing stream stability problems in a way that was sustainable long-term
and also improved recreational uses and ecological functions. Until that time, the prima-
ry approach used to stabilize streams was to harden the channel and/or streambanks
with such materials as loose rock (rip-rap),
River Or Stream restoration gabion baskets, concrete, retaining walls, etc.
has been defined in many ,Such Pracutlcues addresseud thef sMi^ p*°b'
lems with the stream, but often resulted in a
different terms, but IS generally dramatic loss of ecological function and
Considered tO describe a Set aquatic life due to loss of aquatic cover,
Of activities that help improve appropriate bed materials, shade and food
, sources. In addition, since these "hard" ap-
the environmental health of a proaches did not address overall chann/
Stream. Other terms COm- geometry issues, they often lead to down-
monly USed for Stream restO- stream instability
ration include Stream reda- Prac™rs began to develop techniques
that would not only address stability issues,
mat/on, stream stabilization, but also improve aquatic habitat functions
natural Channel design and and recreational uses, such as fishing. The
Channel rehabilitation, movement began in the US in the Western
states, where there was increasing concern
over the degraded condition of trout and salmon rivers, and spread eastward across the
country. The resulting designs, often referred to as natural channel designs, seek to replicate
the channel forms seen in stable, natural rivers in order to restore stability and functions
to degraded rivers.
Natural channel design can be defined as a stream restoration technique that seeks to
create a stable stream channel that balances its flow of water and sediment over time, so
that the channel does not aggrade or degrade. A variety of methods and tools are avail-
able to practitioners, but nearly all focus on several important design concepts:
• Providing connection between the channel and its floodplain (floodplain connectivity);
• Sizing low-flow channels to carry a given flow that over time carries the most sedi-
ment (channel-forming discharge concept);
• Designing channels to carry both their water and sediment loads; and
• Constructing channels to mimic the functions of natural channels to the extent possible.
A Function-Based Framework » May 2012 34
-------
Chapter 3: Watershed and River Corridor Processes
For more information on specific design components commonly used in the practice of
stream restoration, see the NRCS National Engineering Handbook Part 654 — Stream
Restoration Design (USDANRCS, 2007) directives.sc.egov.usda.gov/viewerFS.aspx?id=3492.
In 2008 the USAGE and EPA issued regulations improving and standardizing mitigation
policies, and increasing the emphasis placed on
the restoration of functions. The rules specifi- Natural channel design can be
cally identify streams as a difficult-to -replace def/ne£/ gs g stream restoration
resource tor which avoidance and minimiza-
tion should be emphasized. Where compensa- technique that Seeks to Cre-
tory mitigation for streams is needed, the rules ate a Stable Stream channel
emphasize in-kind rehabilitation, enhancement thgt balances its flow of wa-
or preservation and outline stream specific
considerations for site selection, providing ter and Sediment Over time,
design plans for review, monitoring require- SO that the channel does not
ments and ecological performance standards. aggrade Of degrade.
This increased emphasis on the restoration of
streams ensures that techniques such as natural
channel design will continue to be the preferred methods for river restoration. For more infor-
mation on natural channel design techniques for river restoration, see FISRWG (1998) and
USDA NRCS (2007).
3.8 » PRIORITY LEVELS OF RESTORATION
Priority Levels for the restoration of incised streams were developed by Rosgen (1997).
The "Rosgen Priority Levels" range from Priority Level 1 to Priority Level 4 and are chosen
based on factors including both physical and economic constraints. These Priority Levels
are often referred to in stream mitigation programs as restoration approaches (USAGE
Wilmington District et al., 2003; USAGE Savannah District, 2004; and USAGE Norfolk
District and VDEQ, 2007). For example, a Priority Level 1 is often considered the highest
level of restoration and receives the most credits per foot, while Priority Level 3 approach-
es often receive enhancement level credits. Chapter 11 and Appendix B of this document
illustrate how select Priority Levels can be merged into a more function-based approach
to developing stream credits. A brief description of the Priority Levels is provided below,
and a more detailed description can be found in Rosgen (1997).
A Priority Level 1 restoration creates a new stable channel that is reconnected to the
previous (higher in elevation) floodplain. A new stream channel is excavated on the
original floodplain by raising the stream bed elevation. This approach requires an abrupt
change in bed elevation at the upstream end of the project, e.g., culvert outfall or knick-
point. The former incised channel is filled, converting it to a floodplain feature. This
approach is used in areas where there are few lateral constraints and where flooding on
the adjacent land can be increased. An example of the plan form and dimension improve-
ments created by a Rosgen Priority 1 is shown in Figure 3.8.
A Function-Based Framework » May 2012 35
-------
Chapter 3: Watershed and River Corridor Processes
FIGURE 3.8 ROSGEN PRIORITY LEVEL 1 RESTORATION APPROACH
PLAN VIEW
Existing
Incised Channel
Flow
Wetlands
CROSS SECTION
Bankful
Existing
Incised Channel
A Function-Based Framework » May 2012
36
-------
Chapter 3: Watershed and River Corridor Processes
A Priority Level 2 restoration also creates a new stable channel that is connected to the
floodplain, but the floodplain is excavated at the existing bankfull elevation, i.e., the bed
elevation of the stream remains nearly the same. The formerly channelized and incised
stream is re-meandered through the excavated floodplain. This approach is typically used
if there is not a knickpoint or other abrupt change in grade upstream of the project, in
larger streams, or in cases where flooding cannot be increased on adjacent property. A
plan view and cross-section example is shown below in Figure 3.9.
FIGURE 3.9 ROSGEN PRIORITY LEVEL 2 RESTORATION APPROACH
PLAN VIEW
Cross Section
Existing
Incised Channel -i
Flow
Existing
Incised
Channel
A Function-Based Framework » May 2012
37
-------
Chapter 3: Watershed and River Corridor Processes
A Priority Level 3 restoration converts a channelized and incised channel, often with
poor bed form diversity, into a step-pool type of channel. The existing channel alignment
stays nearly the same. Bankfull benches are excavated at the existing bankfull elevation
to provide limited floodplain connectivity. In-stream structures are required to dissipate
energy along the streambanks and to create step/pool bed forms. Priority Level 3 is often
used where constraints inhibit meandering and flood elevations cannot be increased, e.g.,
urban environments. A plan view and cross-section example is shown below in Figure 3.10.
FIGURE 3.10 ROSGEN PRIORITY LEVELS RESTORATION APPROACH
PLAN VIEW
Cross Section
Restored
Channel -i
Flow
A Function-Based Framework » May 2012
38
-------
Chapter 3: Watershed and River Corridor Processes
A Priority Level 4 stabilizes the channel in place, using in-stream structures and
bio engineering to decrease stream bed and streambank erosion. This approach is typi-
cally used in highly constrained environments, such as backyards and highway right-of-
ways. A Priority Level 4 is rarely used to create stream mitigation credits and is generally
not considered restoration, only stabilization.
3.9 » IMPORTANCE OF SITE SELECTION IN RIVER RESTORATION
In the context of watershed health and the restoration of river functions, initial selec-
tion of river restoration sites is critically important. Sites that will provide the most
functional lift are those that have few restoration constraints, have relatively healthy
watersheds upstream, and have causes of impairment that are linked to the reach itself.
An example would be a stream that is heavily degraded by direct cattle access, but has a
relatively healthy watershed upstream and good water quality flowing into the site. In
this situation, the primary causes of impairment are linked to the river restoration site
itself, and include loss of riparian vegetation from grazing, eroding streambanks due to
loss of vegetation and hoof-shear, elevated
fine sediments in the river due to bank \n f/,e context of watershed
erosion and cattle crossings, and high bacte- ^ ^ ^ ^ restoratjon Qf
rial loads due to cattle fecal matter. Assuming
there are no constraints to the restoration river functions, initial SeleC-
work, such a project has a high probability of tion of Hver restoration sites
providing dramatic functional uplift because /s cr/f/ca//yr important. Sites
the primary sources of impairment can be '
addressed. Excluding cattle from the stream that W"1 P'OVlde the most
system, restoring a proper river form and functional lift are those that
restoring riparian vegetation will greatly have few restoration COn-
decrease sediment and bacteria loads, provide . . ,. .
, , , . , , j. stramtsf have relatively
improved aquatic habitat, provide shading
and carbon sources, and improve overall healthy watersheds
channel stability and function. Stream, and have C3US6S of
in contrast, consider a proposed restora impairment that are linked to
tion site that is highly constrained by adja- .
cent buildings and the streamflow entering *"e reacn itselt.
the site is of poor quality. In this situation,
the functional lift provided by stream restoration practices will be minimal, as the causes
of watershed impairment are upstream of the project and restoration approaches are
limited by the site constraints. Such a restoration site could address local instability, but
will provide little in the way of water quality benefits.
The chapters that follow discuss the restoration of stream functions in depth; however,
the practitioner should always be mindful that the degree to which functional lift can be
provided is determined at the site selection phase of a project.
A Function-Based Framework » May 2012 39
-------
y i _ yii Didf IK
A Function-Based Framework » May 2012 40
-------
Chapter 4
The Stream Functions Pyramid
The Stream Functions Pyramid, developed by Harman (2009), provides a framework
that organizes stream functions in a pyramid form. The Stream Functions Pyramid
illustrates that stream functions are supported by lower-level functions in a hierarchical
structure. The Pyramid is a useful tool in goal setting, developing and reviewing stream
assessment methodologies, and creating standard operating procedures (SOPs) for regula-
tory and non-regulatory stream restoration programs. This chapter provides a detailed
overview of the Stream Functions Pyramid along with simple examples of how it can be
applied. Detailed applications are provided in Chapter 11.
4.1 » FUNCTIONAL OBJECTIVES FOR STREAM RESTORATION
A stream functions framework was created by the US Army Corp of Engineers (US-
ACE) for determining and evaluating objectives for stream restoration projects (Fisch-
enich, 2006). This framework provided the foundation for development of the Stream
Functions Pyramid. It identifies a suite of 15 functions critical to the health of stream and
riparian ecosystems. These functions are summarized in Table 4.1. The USACE function-
al framework is appealing since it has a scientific basis in stream functions, is based on
processes, and attempts to describe the interactions between identified functions.
TABLE 4.1 FUNCTIONS CRITICALTO STREAM AND RIPARIAN ECOSYSTEM HEALTH
(Fischenich2006)
FUNCTION
1. Maintain Stream
Evolution Processes
2. Energy Management
Processes
3. Provide for Riparian
Succession
4. Surface Water Storage
Processes
DESCRIPTION
Maintains appropriate energy levels; promotes diversity
and variability of biotic communities.
Allows for conversion between potential and kinetic
energy through changes in the system.
Changes in vegetation structure promote diversity and
ecological vigor, vegetation necessary for system
stability and nutrient cycling.
Provides temporary water storage during high flows,
regulates soil moisture, provides pathway for aquatic
organism movement, and provides contact time for
biogeochemical processes.
A Function-Based Framework » May 2012
41
-------
Chapter 4: The Stream Functions Pyramid
TABLE 4.1 FUNCTIONS CRITICALTO STREAM AND RIPARIAN ECOSYSTEM HEALTH
(Fischenich2006)
FUNCTION
5. Maintain Surface/
Subsurface Water
Connections and
Processes
6. General Hydrodynamic
Balance
7. Sediment Continuity
8. Maintain Substrate and
Structural Processes
9. Quality and Quantity of
Sediments
10. Support Biological
Communities and
Processes
11. Provide Necessary
Habitats
12. Maintain Trophic
Structures and Processes
13. Maintain Water and Soil
Quality
14. Maintain Chemical
Processes and Nutrient
Cycles
15. Maintain Landscape
Pathways
DESCRIPTION
Provides bi-directional exchange from open channel to
subsurface soils; allows exchange of chemicals, nutrients
and water.
Provides proper flow conditions at the appropriate
seasons for support of the biotic community.
Provides for appropriate erosion, transport and
deposition processes.
Provides substrate and structural architecture to support
diverse habitats and biotic communities.
Determines the physical character of the system relative
to the primary variables: sediment yield and character.
Provides diverse assemblages of native species.
Produces and sustains habitats to support vigorous
aquatic and riparian biotic communities.
Promotes growth and reproduction of biotic
communities across trophic levels.
Promotes favorable conditions for riparian communities
that trap, retain and remove particulate and dissolved
constituents from surface and overland flow.
Provides for complex reactions to maintain equilibrium
and supply required elements to biota.
Maintains connectivity to allow for biotic and abiotic
energy process pathways.
The functions characterized by Fischenich (2006) are ordered into a hierarchy of
functions, where the relative significance of each function is inferred by assessing the
interrelations among functions. Functions that affect the greatest number of other functions
are ranked highest, while functions that have the least effect on other functions are ranked
lower (Table 4.2). For example, the General Hydrodynamic Balance function (1), which
describes a system's flow characteristics, supports directly or indirectly all other functions
listed in the Framework, such as sediment transport, energy, biotic and chemical func-
tions. In contrast, the Provide Necessary Habitats function (15) directly affects three other
functions, which are all related to the biological systems that are supported by streams.
A Function-Based Framework » May 2012
42
-------
Chapter 4: The Stream Functions Pyramid
TABLE 4.2 RANKINGS OF FUNCTIONS PROPOSED BY FISCHENICH (2006)
FUNCTION
1. General Hydrodynamic
Balance
2. Maintain Stream Evolution
Processes
3. Surface Water Storage
Processes
4. Sediment Continuity
5. Provide for Riparian
Succession
6. Energy Management
Processes
7. Maintain Substrate and
Structural Processes
8. Quality and Quantity of
Sediments
9. Support Biological
Communities and Processes
10. Maintain Surface/Subsurface
Water Connections and
Processes
11. Maintain Water and Soil
Quality
12. Maintain Landscape
Pathways
13. Maintain Trophic Structures
and Processes
14. Maintain Chemical
Processes and Nutrient
Cycles
15. Provide Necessary Habitats
FUNCTIONS DIRECTLY
AFFECTED
2,3,4,5,6,7,8,9, 10, 11,
12, 14, 15
1,3,4,5,6,7,8,10,11,12,
14,15
1, 4,6, 10, 11, 12, 14, 15
3,5,6,7,8,9,11,15
1, 2,3,4,6, 12, 14, 15
1,2,3,4,5,7,8,15
1, 2,4,6,7, 10, 15
2,4,5,6,7, 10, 15
5,11,13,14, 15
1,5, 11, 15
8,9,13,14
9, 13, 14, 15
9,11,14
8,9,13
9,12,13
FUNCTIONS INDIRECTLY
AFFECTED
13
9,13
2,5,7,8,9, 13
1,13,14
9, 13
--
5,9, 11, 13
1,9, 11, 14
1,2,3,7,8,10,12
3,9,12,13
5
6
8
6
-
Fischenich (2006) notes that efforts to restore streams are often ineffective because
they fail to address the underlying processes that create and maintain the biological
functions. The purpose of this hierarchy is to indicate the complex set of linkages that
exists between functions of stream and riparian systems and to indicate which functions
are most critical and interrelated to the restoration of stream and riparian functions.
A Function-Based Framework » May 2012
43
-------
Chapter 4: The Stream Functions Pyramid
Fischenich (2006) found that the most critical functions include those that address hydro-
dynamic processes (1, 3, 6), sediment transport processes (4, 7), stream stability (2) and
riparian buffer restoration (5, 11). By addressing these fundamental functions and pro-
cesses, a restored stream and riparian system are capable of supporting more dependent
functions that typically require time to establish, such as diverse biological communities
(9), chemical and nutrient processes (14), diverse habitats (15) and improved water and
soil quality (11).
4.2 » THE STREAM FUNCTIONS PYRAMID
The Stream Functions Pyramid builds on the USAGE work by placing stream func-
tions in a hierarchy. However, the Pyramid uses parameters and measurement methods
that are more often used in stream restoration approaches and assessment methodologies.
It also provides a clear illustration of how physical functions support chemical and bio-
logical functions. This helps scientists, engineers and managers ensure that they are not
only addressing the functions they are directly concerned about, but also the supporting
functions that are required to achieve success.
The Stream Functions Pyramid Framework consists of four components that increase
in detail. First, the broad-level view shows the five functional categories (Levels) with the
underlying controlling variables of geology and climate. Second, function-based param-
eters are provided for each functional cat-
The Stream Functions egory. Third, measurement methods are
Pyramid Framework consists Pro^£ded £°r efh functi™-based parameter.
And fourth, where possible, performance
standards are provided for the measurement
increase in detail, methods. These terms can easily be con-
fused with broader definitions of parameter,
metric, tool and others. To help avoid confusion, definitions for these terms along with
the criteria used to select function-based parameters, measurement methods and perfor-
mance standards are provided below. See Appendix A for the entire Stream Functions
Pyramid Framework. Also reference the Stream Functions Pyramid page at www.stream-
mechanics.com for updates and examples of how the Pyramid is being used.
Typically, the Pyramid is applied at a reach scale even though some of the functions
occur at a watershed scale, e.g., hydrology functions. Applications are discussed in detail
in Chapter 11, including examples of how the Pyramid can be used in reach-scale func-
tion-based assessments and watershed management plans. However, even when used in
watershed management plans, many of the measurement methods described below are
conducted at a reach scale. The reach scale information can then be used in the broader
context of watershed health, i.e., providing reaches that are functionally impaired or
healthy, and as an aid in identifying potential restoration sites.
4.3 » STREAM FUNCTIONS PYRAMID: BROAD-LEVEL VIEW
The broad-level view is shown in Figure 4.1. The functional categories have been
A Function-Based Framework » May 2012 44
-------
Chapter 4: The Stream Functions Pyramid
modified from Fischenich (2006) to more closely match functions with parameters that
are commonly used in the fields of hydrology, hydraulics, geomorphology, physicochem-
istry (called physicochemical on the Pyramid) and biology. The purpose of the broad-level
Pyramid view is to show that the primary direction of cause-and-effeet relationships
flows from the bottom of the Pyramid to the top. In other words, functions higher on the
Pyramid are more dependent on lower-level functions. This does not mean that cause-
and-effect relationships can't or don't flow from higher levels to lower levels. The inten-
tion of the Pyramid is to show the dominant flow of cause-and-effect relationships. A
dashed line is used to separate the functional categories to illustrate that the transition
between categories is not a "hard" boundary. Cause-and-effect relationships can flow in
both directions. For example, everything in the Pyramid is ultimately controlled by
geology and the region's climate. If climate
changes or there is a major geologic event, jhe /nfenf/on of the Pyramid
e.g., volcanic eruption, changes will occur
throughout the Pyramid. Wkhm the Pyra-
mid, Hydrology and Hydraulic functions flow of CSUSe-and-effect
support Geomorphology functions like relationships. A dashed
sedrment transport i.e., without water being ^ fo used ^ rgte the
contributed from the watershed and creating
flow dynamics in the channel, sediment
transport would not occur, of course, chan- illustrate that the transition
nel form (geomorphology) does affect hy- between categories is not a
draulics through channel slope, sediment M,r .„ ,
supply and boundary conditions. This is a
downward example of cause and effect, but it
is not as dominant as the requirement for water to be in the channel. Wohl (2004) alludes
to these cause-and-effect relationships by stating, "We cannot save trout without saving
their river and floodplain habitats. We cannot save river and floodplain habitats — and
the plants and insects of the trout's food web — if we do not also maintain the processes
controlling water and sediment entering the river corridor from the surrounding hill-
slopes and uplands." This concept exemplifies how the underlying physical functions
support the biological functions.
This may seem obvious; however, many assessment methodologies address biological
indicators without addressing the underlying controls provided by geomorphology,
hydraulics and hydrology (Somerville, 2010). This concept also helps the practitioner
match the project goal with the corresponding stream functions to avoid problems where
practitioners design ineffective projects because they ignore the underlying hydrology,
hydraulic and geomorphic functions (Fischenich, 2006).
Function Descriptions by Level
Function-based parameters and measurement methods are not shown on the broad-
level Pyramid. Rather, a statement is provided to define the overall function of a given
A Function-Based Framework » May 2012 45
-------
Chapter 4: The Stream Functions Pyramid
FIGURE 4.1 STREAM FUNCTIONS PYRAMID — OVERVIEW
(See Appendix Afor a full-size version.)
BIOLOGY »
Biodiversity and the life histories of aquatic and riparian life
HYDRAULIC »
Transport of water in the channel, on the floodplain, and through sediments
category. This information is based onFischenich (2006), Somerville (2010), industry
standards and professional experience. A description is provided below for each functional
category. These statements are used to help select function-based parameters in the next
Pyramid view.
Level 1: Hydrology
Hydrology functions transport water from the watershed to the channel. Hydrology is
placed at the bottom of the Pyramid because water contributed from the watershed
strongly affects the higher-level functions. Very simply put, without surface water flow,
there would not be channel formation and the subsequent aquatic ecosystem. This
definition of hydrology is most common in the engineering community and although it is
related to hydraulics, the calculations are made separately, e.g., the USAGE hydrologic
model HEC-HMS (Scharffenberg and Fleming, 2010) and the USAGE hydraulic model
HEC-RAS (Brunner, 2010). Physical and life scientists tend to merge hydraulics into
hydrology. However, from a stream assessment and restoration perspective, there are
advantages to having both categories. The Pyramid keeps these functions separate for
two reasons: 1) When conducting assessments or implementing a stream restoration project,
it is important to distinguish between watershed scale functions of water transport
(Hydrology) and reach scale relationships that describe how water interacts with the channel
A Function-Based Framework » May 2012
46
-------
Chapter 4: The Stream Functions Pyramid
(Hydraulics); and 2) The opportunity for functional lift is very different between the two.
Level 2: Hydraulics
Hydraulic functions transport water in the channel, on the floodplain and through sedi-
ments. Again, this is a broad statement — it defines how water behaves once it reaches a
channel and how it interacts with the bed, banks, floodplain, hyporheic zone, etc. (Ding-
man, 2008). It is important to note that this function works in channels of all sizes, from
valley bottom swales (ephemeral channels) to large rivers. It is also present in all forms of
geology and climate zones (Knighton, 1998). The energy associated with moving water
has the ability to do work, such as transporting sediment, which is a geomorphology
function (Leopold et al., 1992). The Hydraulic functions are closely related to Geomor-
phology functions and many interrelationships exist between these two categories. For
example, sinuosity (Level 3) affects channel slope, which in turn affects channel velocity
(Level 2). However, the dominant cause-and-effect relationships involve Hydraulics
supporting Geomorphology. At a basic level, water must be present in the channel before
sediment can be moved, regardless of sinuosity and other measures of channel form.
Hydraulic functions also affect many functions in Levels 4 and 5 because they determine
the amount of force and power that is exerted by the water on aquatic habitats.
Level 3: Geomorphology
The function of geomorphology, as defined here, is the transport of wood and sedi-
ment to create diverse bed forms and dynamic equilibrium. The relative importance or
even presence of certain Geomorphology functions varies greatly with changes in geol-
ogy and climate. For example, wood transport and storage is extremely important to
channel stability in headwater mountain streams but not important in low-gradient,
grassland streams. In addition, some streams are naturally unstable and are not in a state
of dynamic equilibrium, e.g., glacial outwash plains and some alluvial fans. However, the
Hydrology and Hydraulic functions come together with the Geomorphology functions to
create a channel form that is appropriate for the underlying geology and climate of the
region. From a stream assessment and restoration perspective, we are most interested in
these functions as they relate to the creation of diverse bed forms and channel stability
(dynamic equilibrium) that has a dramatic effect on Level 4 and 5 functions, which are
often the ultimate desire of a restoration project.
Level 4: Physicochemical
Physicochemical functions include temperature and oxygen regulation, and processing
of organic matter and nutrients. These functions are generally more affected by the
underlying functions than vice versa, even though some of these functions occur as soon
as water is present in the channel, e.g., water temperature. However, the Physicochemical
category was placed above Geomorphology because a restoration practitioner would
typically address functions here (Level 3) in order to see improvements in Physicochemi-
cal functions. For example, fast riffles and deep pools (bed form diversity), along with
A Function-Based Framework » May 2012 47
-------
Chapter 4: The Stream Functions Pyramid
shade and a wide buffer help regulate stream temperature. It is true that some projects may
only need to address water-quality stressors, e.g., a point-source discharge and animal
waste inputs, rather than restore the underlying functions. However, even in these cases,
an assessment should be made to ensure that the underlying, supporting functions are
present so that the stream will naturally recover once the stressor is removed.
Level 5: Biology
Biology is located at the top of the Pyramid because these functions are dependent on
all the underlying functions. These functions include the biodiversity and the life histo-
ries of aquatic and riparian organisms. Biology functions can affect lower-level functions,
e.g., beaver activities; however, as with the other levels, the dominant cause-and-effect
relationship is upward. A healthy aquatic ecosystem must have sufficient water contrib-
uted from the watershed, the right levels of hydraulic forces, proper bed form diversity
and channel stability, suitable temperature and oxygen regimes, and so on. The value of
the Pyramid at this level is that it helps regulators, scientists and engineers to identify the
underlying functions that must be present in order to achieve functional improvements in
biology. This is currently not happening. As Somerville (2010) points out, many assess-
ment methods omit these underlying functions.
4.4 » STREAM FUNCTIONS PYRAMID: FUNCTION-BASED PARAMETERS
Figure 4.2 shows a more detailed view of the Pyramid with examples of function-
based parameters that can be used to quantify or describe the functional statement provided
in the broad-level view. The term "function-based" is used to acknowledge that the
parameter may be a "structural" type of parameter or an actual function. Structural
parameters describe a stream condition at a
_, — . point in time, e.g., percent riffle and pool. A
function parameter is expressed as a rate and
Pyramid USeS the term directly relates to a stream process that helps
function-based parameter tO create and maintain the character of the
take the emphasis off of feam C01?dor (A!lan' 19U95)" Thef Stream
Functions Pyramid uses the term tunction-
StruCtural measures verSUS based parameter to take the emphasis off of
actual functions. Rather, structural measures versus actual functions.
function-based parameters Rather' function-based parameters are used
individually or in combination to quantify
or describe a particular aspect of the func-
Combination tO quantify Or tional statement provided in the broad-level
describe a particular view- For example, within the Hydrology
aspect Of the functional category (Level 1), flood frequency is a
function-based parameter that can be used
Statement provided in the to quantify the occurrence of a given dis-
broad-level View, charge. It is not a function, but it does
A Function-Based Framework » May 2012 48
-------
Chapter 4: The Stream Functions Pyramid
provide critical information about the transport of water from the watershed to the
channel, which is a function. Another example is bed form diversity, a function-based
parameter in Geomorphology (Level 3). Bed form diversity is not a function, it is a struc-
tural measure. However, complex bed form diversity, e.g., gravel riffles with low embed-
dedness and slow-moving deep pools are an
indication that sediment transport processes The function-based
are working appropriately. Sediment trans-
f T u parameters shown on the
port is a function; however, it is much more
difficult to measure than bed form diversity Pyramid are fairly comprehen-
and may not be necessary for stream assess- Sl've and Can be USed in a
ments that are focused on functionality. This \M\rta rannf* nf «pM7rm«
does not mean that sediment transport
should not be assessed for vertical stability or "
for a restoration design. In the end, stream Considered as examples.
assessments and designs may include a mix
of structural measures and functions based on the complexity of the project and financial
constraints. However, the combination of structural measures and functions can be
considered function-based if they help describe or quantify a particular functional cat-
egory, as expressed by the functional statement in Figure 4.1 (The Stream Functions
Pyramid — Overview).
The function-based parameters shown on the Pyramid are fairly comprehensive and
can be used in a wide range of settings. However, they should be considered as examples.
Some parameters may be more important than others for a given region. In addition,
some regions or unique projects within a region may need to add parameters. The criteria
used to include function-based parameters within the Pyramid are provided below.
Criteria for Selecting Function-Based Parameters
For all Pyramid Levels
• Quantifies or describes (typically quantitative, but can be qualitative) a portion of the
functional statement. The functional statements are provided above in Function
Descriptions by Level.
• Has at least one measurement method that can be assigned. A function-based
parameter can typically be measured in multiple ways, hence, it is broader than
a measurement method.
• Can be a structural measure or a function.
• May or may not be applicable to all climate zones, geologic settings and eco-regions.
For Levels 1 through 3
• Must be a parameter that a practitioner can calculate or measure and use for restora-
tion design and/or stream assessments.
• For restoration projects, typically include parameters that can be manipulated by the
practitioner to create functional lift.
A Function-Based Framework » May 2012 49
-------
Chapter 4: The Stream Functions Pyramid
For Levels 4 through 5
• If adding a parameter to these Levels, consider if there are supporting lower-level
parameters.
Ultimately, the suite of parameters selected will be dependent on the project's goals
and budget, since some parameters can be measured quickly and inexpensively and
others require long-term monitoring and expensive equipment. These issues can be
addressed by selecting the appropriate measurement method. Chapter 11 provides ex-
amples of how to select parameters and measurement methods for various applications.
FIGURE 4.2 STREAM FUNCTIONS PYRAMID — FUNCTIONS & PARAMETERS
(See Appendix A for full-size version.)
I
BIOLOGY » FUNCTION: Biodiversity and the life histories of aquatic
and riparian life » PARAMETERS: Microbial Communities, Macrophyte
Communities, Benthic Macroinvertebrate Communities, Fish Communities,
Landscape Connectivity
PHYSICOCHEMICAL » FUNCTION: Temperature and oxygen regulation; processing
of organic matter and nutrients » PARAMETERS: Water Quality, Nutrients, Organic Carbon
Transport of wood and sediment to create diverse bed forms and dynamic
equilibrium » PARAMETERS: Sediment Transport Competency, Sediment Transport Capacity, Large Woody Debris
Transport and Storage, Channel Evolution, Bank Migration/Lateral Stability, Biparian Vegetation, Bed Form Diversity,
Bed Material Characterization
HYDRAULIC » FUNCTION: Transport of water in the channel, on the floodplain, and through sediments » PARAMETERS: Floodplain
Connectivity, Flow Dynamics, Groundwater/Surface Water Exchange
' » FUNCTION: Transport of water from the watershed to the channel » PARAMETERS: Channel-Forming Discharge, Precipitation/Runoff
Relationship, Flood Frequency, Flow Duration
4.5 » STREAM FUNCTIONS PYRAMID: MEASUREMENT METHODS
Table 4.3 shows examples of measurement methods associated with each parameter.
Measurement methods are more specific than function-based parameters by including
specific calculations, simple spreadsheet models, sophisticated computer models, rapid
field-based assessments, and in some cases, assessment methods that influence more than
one function-based parameter. However, unlike the function-based parameter, there is
typically a well-defined approach for conducting the measurement method.
Most parameters have at least two measurement methods and some, like the Geomor-
A Function-Based Framework » May 2012 50
-------
Chapter 4: The Stream Functions Pyramid
phology category, have several for each Measurement methods are
parameter. Some measurement methods are mQfe jfjc than function.
rapid-based approaches (requiring a small
amount of time and effort to make the
measurement) and others require intensive including Specific Calculations,
monitoring and analysis. This provides the simple Spreadsheet models,
user with a wide selection of methods to
quantify, describe, and understand stream
functions. General descriptions about the models, rapid field-based
individual measurement methods are pro- assessments, and in SOme
vided in Chapters 6-10. These chapters ^ assessment methods
correspond to a functional category (Hydrol-
ogy, Hydraulics, etc) with the measurement
methods under the function-based parameter function-based parameter.
sections. This document does not provide a
lot of detail about how the measurement methods relate to each other. As real-world
applications are developed, these relationships should become clearer. In the meantime,
users will find links and references to additional resources that can be used to develop a
more comprehensive understanding of how multiple measurement methods can be used
together to quantify a function-based parameter.
Ultimately, the suite of function-based parameters and measurement methods
selected will depend on the purpose of the assessment and the funding level. Again,
Chapter 11 provides examples of how to select parameters and measurement methods
for various applications.
Table 4.3 provides a list of all the measurement methods associated with the function-
based parameters that have been included in this document. These measurement meth-
ods should not be considered all-inclusive, but rather, represent examples that are fre-
quently used in stream assessment and restoration. A more detailed table is provided in
Appendix Ac that includes additional information about each measurement method,
including: type, level of effort, level of complexity, and whether or not the measure is a
direct versus indirect measurement of a function-based parameter. The criteria used to
make these determinations are provided below and details for each parameter are pro-
vided in Chapters 6-10.
Type of Measurement Method
As discussed above, the measurement methods include a wide range of tools, tech-
niques, metrics and even assessment approaches. Appendix Ac identifies each type of
measurement method, using the following criteria/definitions:
• Tool: Includes spreadsheet and computer models, typically with predictive ability.
Tools are more automated than a technique.
• Technique: Techniques are empirical equations, statistical approaches and field survey
techniques/methods. Techniques are not part of a larger computer model/tool, e.g.,
HEC-RAS, which is a tool.
A Function-Based Framework » May 2012 51
-------
Chapter 4: The Stream Functions Pyramid
• Metric: A metric or parameter, which is more specific than a function-based param-
eter. It has a well-defined method for being measured. For example, flow dynamics is
a function-based parameter and velocity is a measurement method of the metric type.
This is a subtle, but important difference.
• Assessment Approach: Includes established assessment approaches, e.g., rapid bioassessment
protocol. It often assesses more than the function-based parameter shown in the Pyramid,
meaning that the Pyramid is only referring to a portion of the assessment methodology.
Level of Effort
Appendix Ac assigns a level of effort to each measurement method, including rapid,
moderate and intensive. The overriding criteria is to determine how much effort is
required to arrive at a final answer, so level of effort can include field and office/lab work.
In general, rapid measurement methods require less than half a day in the field to assess a
one-mile stream reach. Some rapid measurement methods use simple spreadsheets, maps
or other office-based measurement methods that do not require field work. Other mea-
surement methods, like regional curves, are simple to use if the curve has been developed,
moderate if developing a watershed specific curve, and intensive for developing regional
curves for a hydro-physiographic region. A moderate level of effort generally requires one
day to one week of fieldwork for a one-mile stream assessment and another day or more
to process and analyze the data. Some methods may not require field data, but still
require time to collect existing data, e.g., from websites and databases. The results can be
compared to existing performance standards and do not require monitoring over time,
e.g., annual surveys to determine functionality. Intensive measurement methods require
long-term (multi-year) monitoring efforts in order to develop trends that are often com-
pared to reference conditions. The actual monitoring effort may be rapid, i.e., it takes less
than half a day to assess one mile of stream; however, achieving results will take multiple
measurements over time to develop a trend and is therefore intensive. The level of effort
should not be confused with level of expertise, since some of the more qualitative and rapid
measurement methods rely on professional judgment and, therefore, a high level of expertise.
Level of Complexity
Appendix Ac assigns a level of complexity to each measurement method, including
simple, moderate and complex. Simple methods can be assessed after minimal training,
e.g., on-the-job training and workshops. Simple can also mean that the sample is relatively
easy to collect and analyze without the need of sophisticated equipment. Simple methods
do not require elaborate or lengthy steps or processes to acquire the data. Moderately
complex measurement methods require more effort and expertise than simple methods.
These measurement methods often require someone with formal training and some
experience. They may also require several steps to collect and analyze the data or to
make calculations and estimates. Complex measurement methods should be completed by
professionals with sufficient academic training and professional experience. These meth-
ods often require complex field and/or office procedures or complex modeling and analysis.
A Function-Based Framework » May 2012 52
-------
Chapter 4: The Stream Functions Pyramid
Direct Versus Indirect
Appendix Ac also shows if the measurement method is a direct or indirect measure of
the function-based parameter. Direct measurement methods often do not require addi-
tional interpretation about the function-based parameter; they directly measure or assess
the parameter. Indirect measures may require additional interpretation or only provide a
partial, or incomplete, understanding of the function-based parameter. Assessment approach-
es typically include the additional interpretation needed for translating indirect measures
to function-based parameters. Direct measures provide a more straightforward answer
about a function-based parameter, whereas an indirect measure is more of an estimate.
TABLE 4.3 PARAMETERS AND MEASUREMENT METHODS
HYDROLOGY
PARAMETER
Channel-Forming Discharge
Precipitation/Runoff Relationship
Flood Frequency
MEASUREMENT METHOD
1. Regional Curves
1. Rational Method
2. HEC-HMS
3. USGS Regional Regression Equations
1. Bulletin 17b
Flow Duration
HYDRAULICS
1. Flow Duration Curve
2. Crest Gage
3. Monitoring Devices
4. Rapid Indicators
PARAMETER
MEASUREMENT METHOD
Floodplain Connectivity
1. Bank Height Ratio
2. Entrenchment Ratio
3. Stage Versus Discharge
Flow Dynamics
1. Stream Velocity
2. Shear Stress
3. Stream Power
Groundwater/Surface Water Exchange
GEOMORPHOLOGY
PARAMETER
1. Piezometers
2. Tracers
3. Seepage Meters
^^M
MEASUREMENT METHOD
Sediment Transport Competency
1. Shear Stress Curve
2. Required Depth and Slope
3. Spreadsheets and Computer Models
A Function-Based Framework » May 2012
53
-------
Chapter 4: The Stream Functions Pyramid
TABLE 4.3 PARAMETERS AND MEASUREMENT METHODS (CONT.)
GEOMORPHOLOGY
PARAMETER
Sediment Transport Capacity
Large Woody Debris Transport and
Storage
Channel Evolution
Bank Migration/Lateral Stability
Riparian Vegetation
Bed Form Diversity
Bed Material Characterization
MEASUREMENT METHOD
1. Computer Models
2. FLOWSED and POWERSED
3. BAGS
1. Wohl LWD Assessment
2. Large Woody Debris Index
1. Simon Channel Evolution Model
2. Rosgen Stream Type Succession Scenarios
1. Meander Width Ratio
2. BEHI/NBS
3. Bank Pins
4. Bank Profiles
5. Cross-Sectional Surveys
6. Bank Stability and Toe Erosion Model
1. Buffer Width
2. Buffer Density
3. Buffer Composition
4. Buffer Age
5. Buffer Growth
6. Canopy Density
7. Proper Functioning Condition (PFC)
8. NRCS Visual Assessment Protocol
9. Rapid Bioassessment Protocol
10. Watershed Assessment of River Stability
and Sediment Supply (WARSSS)
11. USFWS Stream Assessment Ranking
Protocol (SAR)
1. Percent Riffle and Pool
2. Facet Slope
3. Pool-to-Pool Spacing
4. Depth Variability
1. Size Class Pebble Count Analyzer
2. Riffle Stability Index (RSI)
A Function-Based Framework » May 2012
54
-------
Chapter 4: The Stream Functions Pyramid
TABLE 4.3 PARAMETERS AND MEASUREMENT METHODS (CONT.)
PHYSICOCHEMICAL
PARAMETER
Water Quality
Nutrients
Organic Carbon
MEASUREMENT METHOD
1. Temperature
2. Dissolved Oxygen
3. Conductivity
4. pH
5. Turbidity
1. Field test kits using reagents reactions
2. Laboratory analysis
1. Laboratory analysis
BIOLOGY
PARAMETER
Microbial Communities
Macrophyte Communities
Benthic Macro in vertebrate
Communities
Fish Communities
Landscape Connectivity
MEASUREMENT METHOD
1. Taxonomic Methods
2. Non-Taxonomic Methods
3. Biological Indices
1. Taxonomic Methods
2. Non-Taxonomic Methods
3. Biological Indices
1. Taxonomic Methods
2. Non-Taxonomic Methods
3. Biological Indices
1. Taxonomic Methods
2. Non-Taxonomic Methods
3. Biological Indices
1. Spatial Analysis
2. Species Tracking
3. Habitat Models
4.6 » FUNCTION-BASED PARAMETERS AND MEASUREMENT METHOD:
DESCRIPTIONS BY CATEGORY
A more detailed description of the function-based parameters and measurement
methods shown in Table 4.3 is provided below. These descriptions are stratified by
functional category and discuss how the function-based parameters and measurement
methods work together. In addition, information is provided about how the parameters
and measurement methods relate to stream restoration.
Level 1: Hydrology
The function-based parameters shown on the Pyramid are used by practitioners to
A Function-Based Framework » May 2012
55
-------
Chapter 4: The Stream Functions Pyramid
determine how much water will reach the channel and how much water the channel
should carry to maintain dynamic equilibrium. The parameters used to assess these
functions include precipitation/runoff relationships, channel forming discharge, flood
frequency and flow duration. Each parameter and its associated measurement method are
discussed in detail in Chapter 6.
Hydrology parameters are typically independent parameters in a stream restoration
project, meaning, for example, that a designer does not have the ability to influence or
change the precipitation/runoff relationship or channel forming discharge. These param-
eters are simply quantified and then used as inputs for a more detailed hydraulic analysis.
While this is common, it is not always the case. There are scenarios where a project may
be able to "improve" the runoff relationship, such as by implementing stormwater best
management practices. This can be a critical component of stream restoration projects in
urban environments.
Level 2: Hydraulic
Results from Level 1 are used as input parameters in Level 2 to quantify two broad-
level parameters: floodplain connectivity and flow dynamics. Floodplain connectivity is
measured by the bank height ratio, entrenchment ratio and stage-versus-discharge rela-
tionships (rating curves). These measurement methods are used to determine if the
channel can accommodate the targeted volume of water consistent with design goals
and/or management objectives. The bank height ratio is a common method used to assess
floodplain connectivity by comparing the bankfull depth to the total depth of the chan-
nel. Ideally, channels should not carry more than the bankfull discharge. For streams in
alluvial valleys, flood flows should be spread across the floodplain. The entrenchment
ratio, which describes the width of the floodprone area in relation to the bankfull width,
is used to further describe floodplain connectivity (Rosgen 2009). In addition, estimates
of the stage-versus-discharge relationship can be measured or estimated to directly assess
floodplain connectivity. Flow dynamics is assessed through measures of velocity, shear
stress and stream power, which change with increasing stage and discharge. Groundwa-
ter/surface water exchange is also included because this is an important process that
supports physicochemical and biological processes that will be described later (Knighton,
1998). A detailed description of each Hydraulic parameter and its measurement method is
described in Chapter 7.
Like Hydrology, Hydraulic parameters and measurement methods include structural
measures and functions. Discharge and groundwater/surface water exchange are functions
and can be quantified as rates-per-unit time, and they have a significant effect on the
form of the channel and influence functions in Levels 3-5. Bank height and entrenchment
ratios are structural measures, expressed as dimensionless ratios. However, they do relate
to functions since the bank height ratio correlates to the stage that transports the bankfull
discharge, and the entrenchment ratio describes the flow area inundated with the dis-
charge at twice the stage of bankfull. In other words, they help to describe flow dynamics.
Stream restoration projects have the greatest effect on Level 2 and Level 3 functions
A Function-Based Framework » May 2012 56
-------
Chapter 4: The Stream Functions Pyramid
because projects occur at a reach scale and most of these functions can be modified as
part of the design process. For example, the majority of stream restoration projects locat-
ed in alluvial valleys and perennial streams include the goal of reconnecting the stream to
a floodplain. Designers may accomplish this goal by raising the stream bed, lowering the
floodplain or creating a bankfull bench. This approach often follows Rosgen's Priority
Levels of restoring incised channels, as described in Chapter 3 (Rosgen 1997). To accom-
plish this goal, the designer calculates the bankfull discharge (Level 1) and then designs a
cross section that will convey flows up to the bankfull discharge (Level 2). The degree of
functional lift is determined by assessing the difference in pre- and post-restoration
incision, which can easily be represented by the bank height ratio and entrenchment ratio.
Re-establishing floodplain connectivity is one of the most important things that a restora-
tion project can do at a reach scale because it affects so many of the upper-level functions.
Level 3: Geomorphology
The parameters used to assess Geomorphology functions include sediment transport
competency, sediment transport capacity, large woody debris transport and storage,
channel evolution, lateral stability, riparian vegetation, bed form diversity and bed mate-
rial characterization. There are many different measurement methods provided for these
parameters — more than any other category. Of these parameters, sediment transport,
lateral stability and components of the riparian vegetation are quantified as rates and are
considered functional measures. Channel evolution is not measured as a rate, but does
imply a change in form over time and relates to channel-forming processes. However, the
amount of time is not quantified. Bed form diversity is a structural measure, usually
assessed as the percent of riffle and pool length per unit of channel length, depth variabil-
ity and/or substrate distributions. Nevertheless, bed form diversity is an important structural
measure that quantifies the effects of sediment transport and is much easier to assess.
The transport of wood is also an important function in this category, although its degree
of importance varies by stream type. For some stream types (Rosgen A and B), wood
transport and storage is important for maintaining channel stability. For other stream
types (Rosgen C and E) wood and organic matter transport and storage can be important
for stability, but is more important in its role for supporting Level 4 and 5 functions. A
detailed description of each parameter and measurement method is provided in Chapter 8.
Stream restoration designs often focus on Level 3 parameters. Like Level 2, a restora-
tion project can affect these parameters at a reach scale, although the longer the reach the
better with regard to functional lift. Restoration activities associated with Level 3 often
include improving bed form diversity and reducing streambank erosion. Bed form diver-
sity is often improved by designing the appropriate dimension, pattern and profile for the
given valley type. Meandering perennial streams in alluvial valleys, for instance, create
riffle-pool sequences. Large woody debris and in-stream rock and wood structures are
used to further improve depth variability and channel stability and complexity. In addi-
tion, most stream restoration projects include planting vegetation on the streambanks and
the riparian zone to provide bank stability and to support Level 4 and 5 functions.
A Function-Based Framework » May 2012 57
-------
Chapter 4: The Stream Functions Pyramid
Level 4: Physicochemical
Physicochemical functions include physical and chemical processes that create base-
line water chemistry, breakdown organic matter and transform nutrients. It could be
argued that once water reaches the channel (Hydrology and Hydraulic functions) chemi-
cal and biological processes begin to occur. However, from a stream restoration perspec-
tive, these functions are affected (and can be improved) by the presence of water and its
interaction with bed forms, structures like woody debris, and the riparian vegetation. For
example, dissolved oxygen can be increased by lowering the temperature through a
robust riparian buffer and by the presence of steep, rocky riffles. These parameters are
addressed in the lower levels.
Physicochemical water quality assessments include the following parameters: nutri-
ents, organic carbon, dissolved oxygen, temperature, pH, specific conductivity and turbid-
ity. Nutrients and organic carbon can be assessed rapidly in the field with test kits, but are
more often measured in a laboratory. Organic matter and nutrient processing are always
measured as rates and significantly contribute to the character of the stream system;
therefore, these parameters are direct measures of function. Dissolved oxygen, tempera-
ture, pH and conductivity are typically measured at a point in time rather than a rate over
time and are considered a structural measure. However, with continuous monitoring,
parameters such as temperature can be considered a function. For example, the rate of
change in water temperature as air temperature changes is a functional measure of
thermal regulation. A detailed description of each parameter and measurement method is
provided in Chapter 9.
It is difficult for stream restoration projects to directly affect Physicochemical param-
eters because they are affected by so many variables. They are supported by the lower-
level functions, but they are also sensitive to weather and climate change, inputs from
the upstream watershed and adjacent land uses, and even Level 5 functions. The relation-
ship to Level 5 is discussed in more detail below. A reach scale stream restoration project
often has very little control over these factors. Therefore, if a primary goal of a restora-
tion project is to improve these functions, project site selection is as important (if not
more important) than the reach scale activities associated with Levels 1-3, but especially
Levels 2 and 3. The ideal situation for a restoration project that seeks to restore Level 4
functions is to have a healthy upstream watershed and reach scale impairments that can
be improved by restoration activities. In this case, once the reach scale restoration activi-
ties have been completed, the project can benefit from a healthy watershed and not be
limited by poor water quality. Common Level 2 and 3 restoration activities that support
Level 4 functions include floodplain connectivity, bed form diversity, lateral stability,
overhanging vegetation and a wide riparian buffer. This does not mean that Level 4
functions cannot be achieved in the future if the upstream health of the watershed
improves. Watershed management plans are important tools that can combine reach scale
restoration with preservation, stormwater BMP's, and other forms of water quality
improvements to restore watersheds beyond individual stream reaches.
A Function-Based Framework » May 2012 58
-------
Chapter 4: The Stream Functions Pyramid
Level 5: Biology
Biology functions describe the processes that support the life histories of aquatic and
riparian plants and animals. These life histories are dependent on all the lower-level
functions, which is why Biology is at the top of the Pyramid. For instance, healthy fish
populations cannot exist without the proper flow duration, velocity distributions, bed
forms, temperature, water chemistry, etc. that are created through the interactions of all
five levels. Parameters that describe Biology functions include microbial communities,
macrophytes, macroinvertebrate communities, fish communities and landscape path-
ways. A detailed description of each parameter and various measurement methods is
provided in Chapter 10.
Like Level 4, most reach scale restoration activities that support Level 5 occur at Levels
2 and 3. If a project goal is to have a healthy native fish population, the stream reach must
have the proper flow duration, flow dynamics, bed form diversity, lateral stability, vegetative
cover, temperature regulation, dissolved oxygen, pH and conductivity. As discussed in Level
4, site selection is just as critical as the reach scale restoration efforts because the quality of
water and sediments entering the project reach are critical to the health of the aquatic life.
4.7 » STREAM FUNCTIONS PYRAMID: PERFORMANCE STANDARDS
The final layer to the Framework includes performance standards associated with the
measurement methods. The performance standards are divided into functional capacity
types, including: Functioning, Functioning-at-Risk, and Not Functioning, which are
similar to the categories used in the Proper Functioning Condition method (Prichard et
al., 1998). These categories are defined below:
• Functioning: A Functioning score means that the measurement method is quantifying
or describing one or more aspects of a function-based parameter in a way that does
support a healthy aquatic ecosystem. A single functioning measurement method may
not mean that the function-based parameter or overall category (e.g., Geomorphology)
is functioning.
• Functioning-at-Risk: A Functioning-at-Risk score means that the measurement meth-
od is quantifying or describing one or more aspects of a function-based parameter in a
way that can support a healthy aquatic ecosystem. In many cases, this indicates the
function-based parameter is adjusting in response to changes in the reach or the
watershed. The trend may be towards lower or higher function. A Functioning-at-Risk
score implies that the aspect of the function-based parameter, described by the mea-
surement method, is between Functioning and Not Functioning.
• Not Functioning: A Not Functioning score means that the measurement method is
quantifying or describing one or more aspects of a function-based parameter in a way
that does not support a healthy aquatic ecosystem. A single functioning measure-
ment method may not mean that the function-based parameter or overall category
(e.g., Geomorphology) is not functioning.
A Function-Based Framework » May 2012 59
-------
Chapter 4: The Stream Functions Pyramid
Most published performance standards are not described in terms of Functioning,
Functioning-at-Risk or Not Functioning, so professional judgment was required to distrib-
ute the values. Performance standards that are available for each measurement method
are provided in Chapters 6-10, and a summary of all the performance standards is pro-
vided in Appendix Ad. Many of the perfor-
Many Of the performance mance standard values, especially the
dimensionless ratios, should be considered
standard values, especially , , ' jr.,, j
as examples that can be modified based on
the dimenSIOnleSS ratlOS, regional variations in reference condition.
Should be Considered as Some measurement methods do not
examples that can be modified include Performance standards because they
either do not exist or the measurement
method is more associated with design than
in reference Condition, the actual performance of a function-based
parameter. An example is the bankfull
discharge, a Level 1 measurement method for the channel-forming discharge parameter.
The bankfull discharge is used in natural channel designs and geomorphic assessments
and it drives many of the functions in Level 2 and 3, thereby supporting functions in
Levels 4 and 5. It is a critically important measurement method; however, it is a result of the
watershed characteristics and is unique to every stream. Therefore, it would be difficult
to create a reliable performance standard for the bankfull discharge. There are other
measurement methods, such as the bank height ratio used to measure floodplain connec-
tivity, that are closely related to the bankfull discharge, can be much easier to measure,
and have performance standards that can be used, irrespective of geology or climate.
The criteria used to select performance standards, in priority order, include:
• Provided in peer-reviewed journals;
• Provided in government documents;
• Provided in books or proceeding papers; and
• Professional judgment of the authors.
4.8 » STREAM FUNCTIONS PYRAMID AND RESTORATION ACTIVITIES
The above discussion provided an overview of the Stream Functions Pyramid Frame-
work, describing the functions by category and listing the function-based parameters and
measurement methods that can be used to describe the functions. A description of perfor-
mance standards was also provided. In the following section, an example is provided to
illustrate how restoration activities can improve stream functions using the Pyramid as a
guide. This will help explain how a stream restoration project can improve stream functions
at a reach scale or as part of a larger watershed improvement effort. However, not all types
of stream restoration or water quality improvement projects fit neatly into the Pyramid.
A Function-Based Framework » May 2012 60
-------
Chapter 4: The Stream Functions Pyramid
Restoration of Channelized and Incised Channels
The restoration of channelized, incised streams is used as an example because it is a
common approach in areas with well-established stream restoration and mitigation
programs. Therefore, many stream mitigation programs appropriately discuss the impor-
tance of channel evolution and floodplain connectivity in their SOP (USAGE Wilmington
District et al., 2003; USAGE Savannah District, 2004; USAGE Norfolk District and
VDEQ, 2007; and USAGE Charleston District, 2010). Early stream mitigation programs
were prevalent in the eastern United States, a region where channelized and incised
streams are abundant. As mitigation programs continue to develop in the western re-
gions, other types of impairments will increasingly be addressed by stream mitigation
programs. However, incised channels are prevalent throughout the United States and will
continue to be addressed by restoration and mitigation programs.
Background
Channelization is an engineering practice with a long history in the United States,
starting in the 19th century. From 1820 to 1970, more than 200,000 miles of streams and
rivers were channelized to reduce flooding, provide drainage for agriculture, and improve
navigation (Wohl, 2004). Locally, channelization increases drainage and reduces flooding
by increasing stream gradient (typically by straightening the channel), thereby increasing
stream power, which typically leads to further incision (Darby and Thornes, 1992; Hupp,
1992). The increased width, depth and cross-sectional area following channelization and
incision reduce floodplain inundation, decreasing water and sediment storage on the
floodplain (Kroes and Hupp, 2010; Pizzuto, 1987). Shields et al. (2010) compared physical,
chemical and biological functions between an incised channel and non-incised channel
with a similar mix of agriculture and forested land uses in northern Mississippi. The
results of this study showed that the incised channel had turbidity and suspended solids
levels that were two to three times higher than the non-incised channel. Total phospho-
rus, total Kjeldahl nitrogen, and chlorophyll a concentrations were significantly higher in
the incised channel; however, nitrate was significantly higher in the non-incised channel.
There were twice as many fish species with four times the amount of biomass in the
non-incised stream. Correlation analysis showed that hydrologic perturbations were
associated with the water quality degradation, leading the authors to recommend that
ecological engineering should provide as much attention on mediating hydrologic pertur-
bations and habitat quality as on pollutant loading. The research cited above did not use
the Stream Functions Pyramid or the Fischenich (2006) framework; however, it did show
that negative changes to lower-level (physical) functions, like Hydrology, Hydraulics and
Geomorphology (Levels 1-3) had negative impacts on Physicochemical and Biology
functions (Levels 4-5). The research also showed that restoration efforts should address
these lower-level functions in order to show changes in the higher-level functions. Ex-
amples of how to use the Pyramid to link restoration activities to functional improve-
ment is provided below.
A Function-Based Framework » May 2012 61
-------
Chapter 4: The Stream Functions Pyramid
Linking Restoration Approach to Stream Functions Pyramid
Typically, restoration credits are based on restoration and enhancement definitions
that include changes to dimension, pattern and profile (e.g., USAGE Wilmington District
et al., 2003). The Stream Functions Pyramid is a tool that can help change the definitions
of restoration and enhancement to focus on functional lift rather than changes to dimen-
sion, pattern and profile. Consider the example in Table 4.4 showing restoration activities
that are used to restore incised, channelized streams. The restoration activities are shown
in the first column. The second column links a function-based parameter from the Pyra-
mid that is directly improved as part of the design and implementation phase of the resto-
ration activity. The third column shows indirect improvements of other function-based
parameters within the same function cat-
egory (level) or higher. This implies that the
restoration activity and direct manipulation
of function-based parameters in Pyramid
Levels 2 and 3 will support the improvement
of certain function-based parameters in
Levels 2 through 5. The word support is
stressed, because these restoration activities
The Stream Functions Pyramid
is a tool that can help change
the definitions of restoration
and enhancement to focus on
functional lift rather than
changes to dimension,
pattern and profile.
are implemented at a reach scale and cannot
change the condition of the upstream water-
shed. It is possible that poor upstream
conditions can prevent functional lift at the project reach, especially with Level 4 and 5
functions. Performance standards and subsequent monitoring are used to determine if the
direct and indirect functional improvements are actually achieved.
TABLE 4.4 LINK BETWEEN RESTORATION ACTIVITY AND FUNCTIONAL IMPROVEMENT
RESTORATION
ACTIVITY
FUNCTION-BASED
PARAMETER that is directly
changed during the design and
implementation phases
OTHER FUNCTION-BASED
PARAMETERS that are indirectly
supported
Re-connect the
stream to the
floodplain by raising
the channel or
excavating the
floodplain
Level 2 - Floodplain
connectivity
Level 2 - Groundwater/surface
water exchange, flow dynamics
Level 3 - Sediment transport
competency and capacity, bank
migration/lateral stability
Level 4- Nutrients
Level 5 - Microbial Communities,
Macrophyte Communities,
benthic macroinvertebrates, fish
communities
A Function-Based Framework » May 2012
62
-------
Chapter 4: The Stream Functions Pyramid
TABLE 4.4 LINK BETWEEN RESTORATION ACTIVITY AND FUNCTIONAL IMPROVEMENT
(CONT.)
RESTORATION
ACTIVITY
FUNCTION-BASED
PARAMETER that is directly
changed during the design and
implementation phases
OTHER FUNCTION-BASED
PARAMETERS that are indirectly
supported
Re-meander the
stream on the
floodplain
Level 3 - Bed form diversity
Level 2 - flow dynamics,
groundwater/surface water
interaction
Level 3 - Sediment transport
competency and capacity, bank
migration/lateral stability
Level 4-Water quality, Nutrients,
Organic Carbon
Level 5 - Microbial Communities,
Macrophyte Communities,
Benthic macroinvertebrates, fish
communities
Add bed form
structure and
complexity, e.g.
in-stream structures
Level 3 - Bed form diversity
Plant streambank
and riparian
vegetation
Level 3 - Riparian Vegetation
Level 3 - Large woody debris
transport and storage, bed
material characterization
Level 4-Water quality, Nutrients,
Organic Carbon
Level 5 - Microbial Communities,
Macrophyte Communities,
Benthic macroinvertebrates, fish
communities
Level 3 - Bank migration/lateral
stability
Level 4-Water quality, Nutrients,
Organic Carbon
Level 5 - Microbial Communities,
Macrophyte Communities,
Benthic macroinvertebrates, fish
communities
Example Projects that May Not Need the Pyramid
The Stream Functions Pyramid Framework is more applicable to some types of proj-
ects and less to others. Stream restoration projects that involve physical manipulation to
intermittent and perennial stream channels can benefit from the Stream Functions Pyramid.
Stormwater Best Management Practices, regenerative design (Flores et al.; 2011), Low
Impact Development, and other practices that occur in ephemeral channels and uplands
may benefit less from using the Pyramid. In addition, water quality solutions, like treat-
A Function-Based Framework » May 2012
63
-------
Chapter 4: The Stream Functions Pyramid
ing point source discharges and lime dosing, may not need the Pyramid to set project goals
or develop assessment methods. However, even in these cases, it is always appropriate to
ask, "What are the supporting functions that are required to meet the desired result?"
This is important because other problems may exist in addition to the obvious impairment.
For example, low pH is a commonly known problem in many West Virginia streams.
The state agencies have created a dosing program to add lime to the stream and increase
pH. Results have been positive; however, in a presentation at the 2011 Mid-Atlantic
Stream Restoration Conference, Anderson (2011) showed variable improvements in trout
populations. The reasons are not known; however, very little additional information
(other than water chemistry) was collected. The goal of this effort was to restore the
trout fishery. Therefore, an understanding of key functions in all five levels is needed in
order to find a solution. Reducing pH may be the most important part of the solution, but
other function-based parameters may also need to be addressed, e.g., improved bed form
diversity, to recover trout populations.
Implementation of upland stormwater BMPs probably does not need the Pyramid. The
goals of these projects are typically to reduce flow energy, reduce nutrients and remove
other inorganic and organic compounds. These projects would rely more on conventional
approaches to stormwater treatment.
4.9 » APPLICATION OF THE STREAM FUNCTIONS PYRAMID FRAMEWORK
The Stream Functions Pyramid is a conceptual model, a broad-level view showing the
supporting relationships between functions. It also provides examples of function-based
parameters, measurement methods and performance standards. Together they create the
Stream Functions Pyramid Framework. It is not an all-inclusive framework and other
parameters, measurement methods and performance standards can be added. The Pyra-
mid framework is more of a thought process than a set of guidelines, and it is definitely
not a cookbook. As such, it can be challenging to figure out how to start applying the
Pyramid or how to "enter" the Pyramid. This section provides general explanations and
examples about how to think about and apply the Pyramid as it relates to goal setting,
function-based assessments and developing Standard Operating Procedures (SOPs). Refer
to Chapter 11 for more detailed information about how the Pyramid can be applied.
Setting Project Goals and Objectives
Fischenich (2006) reports that a common goal of stream restoration is to restore stream
habitat. However, he points out that habitat has the least effect on the other functions
and is affected by the most functions. The Stream Functions Pyramid can be used by
practitioners to establish goals that are more specific than restoring habitat. It can also be
used to identify and think through the underlying, supporting functions that would need
to be addressed to achieve a desired result.
Restoring habitat as a goal is too broad. One could ask, "Habitat for whom?" Most of
the planet provides habitat for something, so a goal like this does not communicate why
the project is needed or what it hopes to accomplish. A better goal would be to restore
A Function-Based Framework » May 2012 64
-------
Chapter 4: The Stream Functions Pyramid
habitat for a specific species of concern, e.g., native, southern brook trout. Of course, this
goal should come after some form of functional assessment has been completed to deter-
mine that brook trout habitat is in need of restoration and that the watershed can support
brook trout if the reach is restored. The Pyramid framework can assist with this process
by helping the restoration team think through the underlying functions that are needed
to support brook trout. First, it must be acknowledged that restoring brook trout is a Level
5 function; it relates to the life history of an aquatic organism (brook trout). So the team
would "enter" the Pyramid at Level 5. If they enter at Level 5, there must be supporting
functions in Levels 1-4. Now the team must identify those functions and function-based
parameters. Again, this is not a cookbook, and the Pyramid does not automatically
prescribe the supporting functions. This is a thought process that requires qualified
professionals to be able to identify the appropriate parameters. For example, the first
question might be, "What are the Level 4 function-based parameters that are needed to
support native brook trout?" The answer would include appropriate temperate and
oxygen regulation, as trout need cool, highly oxygenated water. Water quality must also
be sufficient to support native brook trout populations, which could be affected by
lower-level functions at a reach scale, as well as the health of the upstream water-
shed. Using the temperature and oxygen regulation as an example to further explore how
the Pyramid can be used, the team might ask, "How do we achieve the proper tempera-
ture and oxygen regulation? What are the supporting function-based parameters?" The
answer is found in Level 3.
Geomorphology function-based parameters like bank migration/lateral stability, bed
form diversity and riparian vegetation affect temperature and oxygen regulation. This is a
critical understanding because these parameters can be manipulated as part of the design
to change oxygen and temperature regulation. For example, the channel form can be
changed to create riffles and deep pools, banks can be stabilized and the riparian corridor
can be planted. The level 4 parameter of oxygen and temperature regulation cannot be
directly manipulated; rather, changes at level 3 are made to affect changes at level 4.
The thought process continues. The team can now ask, "What Hydraulic (Level 2)
function-based parameters are needed to support bank migration/lateral stability, bed
form diversity and riparian vegetation?" In this case, all of the Level 2 function-based
parameters (floodplain connectivity, flow dynamics and groundwater/surface water
exchange) are important to support the identified Level 3 functions, as well as Level 4
functions. Floodplain connectivity minimizes the amount of energy and force within the
channel banks by dissipating flood energy on a floodplain or floodprone area. However,
the appropriate amount of energy is maintained in the channel to support the creation of
appropriate bed forms, e.g., riffles and pools. Floodplain connectivity also affects flow
dynamics and groundwater/surface water interaction, which helps create healthy hypo-
rheic zones that can regulate water temperature and support macroinvertebrate popula-
tions, among other benefits. Floodplain connectivity is also a function-based parameter
that can be directly modified by a restoration team and is often considered the most
important restoration activity because it supports Levels 2-5 functions.
A Function-Based Framework » May 2012 65
-------
Chapter 4: The Stream Functions Pyramid
Finally, the team can ask, "What Level 1 function-based parameters are needed to
support the higher-level function-based parameters listed above?" These function-based
parameters support functions from Level 1 through Level 5. Level 1 function-based
parameters, including channel-forming discharge, precipitation/runoff and flow duration,
are important to restoring native brook trout. The channel-forming discharge is used to
determine how large the channel should be and is directly used to determine floodplain
connectivity. Runoff is a watershed calculation and may or may not be modified based on
the size of the watershed, property control and condition. Flow duration is typically
determined by watershed conditions, but can be moderately improved by some restora-
tion activities. It is important to evaluate these Level 1 parameters to make sure that the
Hydrology can support the project goals. And of course, if the underlying geology or
climate regime does not support brook trout, the project should not be attempted.
This is a simple example of how the Pyramid can be used as a process for developing
and thinking through reach scale project goals. Other function-based parameters could be
identified, but questions about the supporting functions would be the same. And there
are certainly many other goals that could be considered. For example, improving water
quality is another common goal. Like habitat, this goal could be improved by being more
specific. What water quality issues are being addressed (temperature and oxygen, nutri-
ents, conductivity, pH, etc.)? The answer to this question will help the restoration team
identify the supporting functions required to make this improvement and to determine if
restoration activities that change function-based parameters are needed; or the team can
determine if things outside of the Pyramid should be addressed, e.g., a treatment plant or
lime dosing.
The last example discussed here relates to stream mitigation. Many stream mitigation
SOPs (USAGE Wilmington District et al., 2003; USAGE Savannah District, 2004; USAGE
Norfolk District, 2007; USAGE Charleston District, 2010) link restoration credits to
changes in dimension, pattern and profile, based on the Rosgen (1996) definition of a
stable channel. While this is an appropriate definition of channel stability, it does not
explicitly relate to a stream function. This has resulted in numerous projects where the
stated goal is to improve dimension, pattern and profile with no thought given to why
these changes are being made, i.e., what functional improvements are desired. At worst,
this has resulted in projects that have completely reconstructed channels that did not
need reconstruction. At best, it resulted in projects where the improvements were misun-
derstood, e.g., the achievable goal was to reduce sediment supply from eroding stream-
banks, but assumptions were made that it should improve macroinvertebrates. If stream
mitigation programs changed the definition to the restoration of function-based param-
eters identified on the Pyramid, then it could better clarify why the project was being
completed. In addition, the mitigation program could then require the restoration team to
identify the supporting function-based parameters and what restoration activities will be
used to achieve the goal.
A Function-Based Framework » May 2012 66
-------
Chapter 4: The Stream Functions Pyramid
Developing Function-Based Stream Assessment Methods
The Stream Functions Pyramid Framework can be used as an aid to develop function-
based assessments and to select or evaluate existing assessments. It can also be used as a
way to organize watershed assessment plans. The term function-based is used instead of
functional because the Pyramid includes a combination of functions and structural
measures. However, this combination is considered function-based because the param-
eters and measurement methods are used to quantify or qualitatively describe the overall
functional statement for a given Level. A detailed description of how the Pyramid Frame-
work can be applied to function-based assessments, including developing, reviewing and
organizing watershed management plans, is provided in Chapter 11. A general overview
and example is provided below.
Stream assessments can be completed for a wide range of reasons, including but not
limited to: fisheries management; threatened or endangered species recovery plans;
drinking water source assessment; watershed/land use planning; compliance monitoring
for State or Federal permits; documenting water quality trends (Somerville and Pruitt,
2004); before and after comparisons of stream restoration projects; and to determine the
restoration potential for a degraded stream reach. Restoration potential is the highest level
of restoration that can be achieved given the results of the function-based assessment,
health of the upstream watershed and the
project constraints The pyramid Framework may
Somerville (2010) found that the eight , .
, , ? help remedy this problem or
most commoniy assessed parameters tor
L i L " M" * *
regulatory and non-regulatory programs * improve predicative
were: discharge, channel habitat units (bed power by including those
forms), sinuosity, substrate particle size, bank parameters that are known to
stability and dominant bank material, ripar- u • i • -i• •
ian canopy cover, water temperature, and
benthic macroinvertebrates. These param- ^S Somerville (2010) Ulustrat-
eters were often included in categories like ecjf many of fae Current aSS6SS-
physical, chemical and biological to meet the
~/ „; A • •(.(. ment methodologies do not
Clean Water Act categorization of functions
or some form of modification, like habitat. In include hydmlogic parameters.
his study, hydrologic parameters were the
least represented; even though studies like Fischenich (2006) and Shields et al. (2010)
show that hydrologic parameters are critically important to supporting other functions.
Hughes et al. (2010) completed an evaluation of four qualitative indexes of physical
habitat to see if they yielded similar results when applied to streams with varying distur-
bance and ecoregion. They also compared the results with independent assessments of
vertebrate and invertebrate assemblage condition. The results showed that there were
varying meanings of the term "habitat"; however, the different methods did yield similar
results. The results were not as favorable when the physical habitat index scores were
compared to biological index scores. This led the authors to conclude that there is more to
A Function-Based Framework » May 2012 67
-------
Chapter 4: The Stream Functions Pyramid
learn about the factors that control biotic-assemblage structure across broad regional scales.
The Pyramid Framework may help remedy this problem or at least improve predicative
power by including those parameters that are known to support biological conditions. As
Somerville (2010) illustrated, many of the current assessment methodologies do not
include hydrologic parameters. The Pyramid Framework takes this a step further by
providing a structure for assessment developers to select biological parameters and then
supporting parameters that are appropriate for their region. If the Pyramid Level 1-5
categories are used to organize the parameters, it will be easier to identify other support-
ing parameters that should be included.
In addition, since the Pyramid is a hierarchy, a framework is provided that can be used
as a logical structure for creating functional assessment scores or indexes. For example,
parameters lower in the Pyramid may be weighted differently than those higher in the
Pyramid. For these applications, the assessments would likely have a method for sum-
ming values within a category to create an overall value, e.g., a Geomorphology score.
Since measurement methods quantify a portion of a function-based parameter, and the
function-based parameter describes the functional statement within a category, it is
recommended that overall scores take place at the category level. There may be cases
where the score could be made at the function-based parameter level; however, they
should not be made at the measurement method level because a single measurement
method rarely, if ever, fully describes the function-based parameter. Scoring based solely
on an individual measurement method can lead to unintended consequences where the
function-based parameter is not properly assessed, scored, or evaluated. For example,
pool-to-pool spacing and pool depth variability are two measurement methods that
quantify bed form diversity. Used together, they are appropriate indicators of the number
of pools that are present in a study reach and the quality (depth) of those pools. However,
if only one measurement method is used, the result is an inaccurate portrayal of bed form
diversity. If pool depth alone is used, the result could be one deep pool out of a long
stream length, e.g., one pool over a length of 2,000 feet. The score would show that bed
form diversity is functioning when clearly it is not. Just using pool-to-pool spacing could
yield a similar result. A reach could have the appropriate number of pools, but they may
all be too shallow, perhaps from excessive sedimentation or an overly wide channel.
Great care should be given to selecting measurement methods that fully describe the
function-based parameter. And to avoid over emphasizing the measurement method,
scoring should role up to the function-based parameter or category level.
Weighting will also apply to stream mitigation programs that ultimately need to link a
score to debits and credits that relate to functional loss and lift, respectively. A step-wise
approach for developing function-based assessments is provided in Chapter 11. However,
weighting examples are not provided in this document. These examples will come from
actual applications of the Framework and will be made available on the Stream Mechan-
ics website (www.stream-mechanics.com).
A Function-Based Framework » May 2012 68
-------
Chapter 4: The Stream Functions Pyramid
Creating SOPs for Stream Mitigation Programs
The Pyramid can be used by Interagency Review Teams (IRTs) to develop debit and
credit determination methods and performance standards for stream mitigation projects.
This was discussed in the text above regarding stream restoration; and Chapter 11 provides
templates that show how the Pyramid Framework can be used to develop debits and credits.
Appendix B also provides some case studies for a variety of debit and credit scenarios.
Developing SOPs Beyond Stream Mitigation
The Stream Functions Pyramid can serve as an aid in creating SOPs for federal, state
and local programs not associated with stream mitigation. These may include grant
programs, impaired waters programs working on the development of Total Maximum
Daily Loads (TMDLs), non-point source and stormwater management programs and others.
Any program that deals with improving or preserving natural waterways can benefit
from working through the thought process, questions and criteria that are outlined above.
4.10 » SUMMARY
The Stream Functions Pyramid is a simple, conceptual framework. It illustrates that
stream functions should be addressed in a certain order while maintaining the concept
that stream functions are interrelated. Many of the parameters support functions in their
own level, upper levels and sometimes a lower level. It must be restated that the Pyramid
was not developed to capture all the interrelationships between the parameters that are
used to describe the functions. Fischenich (2006) is a better reference for showing specific
interrelationships between functions.
The Pyramid can serve as a communication tool among the various disciplines that
work in the fields of stream assessment, restoration and mitigation. There are very few
individuals who are well versed in all five levels, so having a framework like the Pyramid
makes it easier to communicate across disciplines and helps to ensure that future assess-
ments do not make the same mistake illustrated by Fischenich (2006) and Somerville
(2010), i.e., that most function-based assessments include habitat measures and rarely
include hydrologic functions (split on the Pyramid into Hydrology and Hydraulic). This is
critical because, as Fischenich (2006) and the Pyramid illustrate, these hydrologic func-
tions must be working (at least to some level) in order to support Physicochemical and
Biological functions. Existing assessments may be skewed towards Biological parameters
because they are often prepared by biologists or ecologists who do not have a strong
background in the hydrological sciences or geomorphology. Comparatively, there have
been numerous "channel improvement" projects performed by hydraulic engineers that
just deal with the Hydrology and Hydraulic functions and do not address Geomorphol-
ogy, Physicochemical or Biology functions described by the Pyramid. This trend is chang-
ing and the Pyramid can be used as a guide to develop more comprehensive designs (and
assessments) that address a wider range of stream corridor functions.
A Function-Based Framework » May 2012 69
-------
3.QG iniGniioricuiy LGTI t5i3.riK
A Function-Based Framework » May 2012 70
-------
Chapter 5
Reference Streams
5.1 » USE OF REFERENCE REACH DATA IN THIS DOCUMENT
The concepts of reference stream and reference condition are used throughout this
document. They are used in various performance standards in Chapters 6-10, and tied to
project goals and debit/credit determination methods in Chapter 11. The use of reference
stream condition is most prevalent in the development of performance standards for the
Physicochemical and Biology functions described in Chapters 9 and 10, respectively. The
use of reference condition is also used to develop performance standards for several
Geomorphology measurement methods, e.g., riparian vegetation and bed form diversity.
The reason for this is due to the lack of data
and knowledge about what constitutes
healthy water chemistry, biology and geo-
morphology for every stream in the US.
These parameters are simply too variable
and dependent on all the supporting func-
tions and weather/climate patterns to
The use of reference stream
condition is most prevalent in
the development of perfor-
mance standards for the
Physicochemical and Biology
functions described in Chap-
ters 9 and 10, respectively.
establish universal performance standards.
For example, a bottomland hardwood forest
is common to reference streams in the East,
but certainly not the arid portions of the
West. Some states and regions, however, have better reference condition databases than
other places, and, in these cases, it may be possible to modify the performance standards
to provide specific ranges. Hopefully over time, reference stream databases will be pro-
vided for a wide range of regions and the performance standards can be revised to include
less subjective and more quantitative guidance.
5.2 » BACKGROUND
There are many different views of what a reference stream is and how it should be
used. The term "reference stream" or "reference reach" is used throughout the remainder
of this document to develop measurement methods and performance standards for
certain parameters. Therefore, it is important to have a clear understanding of what is
meant by a reference stream, how it is used in the context of stream assessment and
stream restoration design, how to select stream reference reaches, and how to collect and
analyze the data. An ecosystem reference represents "some target, benchmark, standard,
model or template from which or to which ecosystem biological integrity, structure,
A Function-Based Framework » May 2012
71
-------
Chapter 5: Reference Streams
function, condition or relative health are compared" (Miller et al.; 2011). While a reference
condition can be established for a single stream reach, whenever possible, the reference
condition should come from several stream reaches that can more accurately reflect the
range of natural variability.
Regulatory and non-regulatory stream assessment programs often use the term "refer-
ence condition" to describe the quality of a reference stream. The 2008 Mitigation Rule
defines condition as "the relative ability of an aquatic resource to support and maintain a
community of organisms having a species composition, diversity and functional organi-
zation comparable to reference aquatic resources in the region." The Rule goes on to
define Functions as "the physical, chemical and biological processes that occur in ecosys-
tems" and Functional Capacity as "the degree to which an area of aquatic resource per-
forms a specific function." All of these regulatory definitions point to the need to demon-
strate that a stream restoration project functions like some reference condition, at least
within the constraints established through the project's goals and objectives. Stoddard et
al. (2006) provides a discussion of the various ways that reference condition can be
interpreted, along with definitions of reference condition types, including historical
condition, least-disturbed condition, minimally disturbed condition and best-attainable
condition. Miller et al. (2011) and Pruitt et al. (2012) prepared USAGE technical notes that
build on the Stoddard et al. (1996) concepts of reference condition. Reference condition is
defined as "a contextual background against which the degree of degradation, range of
condition, and benefits of restoration can be measured." The goal of these publications is
to develop a common understanding of the reference condition concept to better interpret
environmental regulations and to improve selection of reference ecosystems to meet
restoration project objectives.
In stream ecosystems, the reference condition can be determined using information
collected from reference streams that are used for comparison with both impaired and
restored reaches, as well as development of a natural channel design for stream restora-
tion. Rosgen (1998) developed the concept of a reference reach approach as a blueprint for
developing a natural channel design. His definition of a reference reach is "a stream that
can transport the flows and sediment produced by its watershed so that the dimension,
pattern and profile are maintained without aggrading or degrading." In the Rosgen defini-
tion, the channel does not necessarily require a pristine condition without human distur-
bance; the stream simply needs to be in balance with watershed flow and sediment
processes. Therefore, this concept of a reference stream focuses more on Hydrology,
Hydraulic and Geomorphology functions (Levels 1-3) than Physicochemical and Biology
functions (Levels 4 and 5). Historically, stream restoration practitioners have focused
more on using reference reaches as defined by Rosgen to better understand Level 1-3 func-
tions because they can directly manipulate, and thereby improve, these functions. How-
ever, with some adaptations to selecting and analyzing reference reach data, these refer-
ence streams can also be used to evaluate the condition and functional lift of Level 4 and
5 functions. Since the approaches are different for Levels 1-3 and Levels 4-5, the site
selection and assessment method sections below are stratified accordingly.
A Function-Based Framework » May 2012 72
-------
Chapter 5: Reference Streams
Uses of Reference Streams in Restoration
Before moving into site selection and assessment methods, more information is needed
on how reference stream data are used. These uses were introduced above and include
the following:
1. As a blueprint for a natural channel design.
2. Structure and function comparison between an impaired stream and a reference
condition, which can be determined using one or more reference streams. This assess-
ment is often completed for:
a. Establishing the baseline condition at a proposed restoration site;
b. Determining functional loss at a site proposed for an impact; and
c. Evaluating the success (functional lift) of a stream restoration project, i.e., establish-
ment of performance standards.
Blueprint for Natural Channel Design
This document does not focus on stream restoration design, so a detailed overview of
how reference reaches are used to develop natural channel designs is not provided. It is
important to note, however, that reference reaches are commonly used by practitioners,
especially those that use the Rosgen method for natural channel design (Rosgen 1998). A
detailed description of how these reference reaches are used in natural channel design
processes is included in the Natural Resources Conservation Service, National Engineer-
ing Handbook, Chapter 11. This handbook is available at directives.sc.egov.usda.gov/
viewerFS. aspx?id=3491.
Comparison Between Impaired/Restored Streams and Reference Streams
Reference streams represent stable and highly functioning channels. Therefore, data
collected from reference streams to determine the reference condition will provide a
standard against which lower-functioning streams can be compared. Comparing a project
reach to a reference stream(s) prior to restoration helps establish the level of impairment.
This information can also help understand the potential to restore stream functions and
to establish realistic project goals. This type of comparison can also be used to evaluate
proposed impact sites. The project stream can be compared to a reference condition to
determine the level of impairment that may occur from the impact, i.e., highly function-
ing streams would have more functional loss than streams that are already impaired.
Reference streams can also be used to evaluate the success of stream restoration
projects. This comparison can be somewhat complicated because a stream restoration
project must evolve for many years before it will function like a reference stream. The
rate of this evolution varies by the functional category (categories shown on the Pyra-
mid). Generally, improvements to Hydraulic functions (Level 2) quickly meet perfor-
mance standards that resemble reference reach conditions. Re-establishing floodplain
connectivity is a great example. The stream is either vertically connected to the flood-
plain or it is not, and connectivity can easily be measured by the bank height ratio at any
riffle along the entire project reach. Functional improvements in Geomorphology (Level
A Function-Based Framework » May 2012 73
-------
Chapter 5: Reference Streams
3) take more time to achieve reference reach conditions, primarily because many of the
processes are affected by the establishment of the riparian buffer. For this reason, most
practitioners design a channel form that will evolve over time as the permanent vegetation
matures. Physicochemical and Biology functions (Level 4 and 5) may take even longer to
represent reference condition, and, depending on the health of the upstream watershed,
they may never evolve to the reference condition. This is why site selection is so important
in choosing a restoration project when the goal is to restore Level 4 and/or 5 functions.
5.3 » SITE SELECTION
Choosing a reference reach will depend on the purpose of the project established by
the goals and objectives. For example, selecting a reference reach for stream restoration
design purposes will require Hydrology, Hydraulic and Geomorphology functions more
so than Physicochemical and Biology functions. The reference reach length may be
shorter and have more water quality impairments than a reference reach selected to
address Physicochemical or Biology functions. Therefore, the site selection criteria de-
scribed below is divided into two sections, one for Levels 1-3 and the other for Levels 4-5.
Geomorphology Reference Reaches (Levels 1-3)
Identifying an appropriate site for a Geomorphology reference reach requires diligence
and time spent in the field assessing potential sites. Reference reaches will be hardest to
locate in areas that have been intensively modified for agriculture, forestry, mining and
development. In these areas, most stream channels have been modified.
Hey (2006) shows that, unlike regional curves, reference reaches do not need to come
from the same hydro-physiographic region as the project site. Therefore, it is important to
look in different regions if a reference cannot be found near the project. In general, Geo-
morphology reference reaches should meet the criteria outlined below:
1. Stable dimension, pattern and profile.
2. Bank height ratio less than 1.2, preferably 1.0 (See Chapter 8, Floodplain Connectivity
section for a description of the bank height ratio).
3. Stable banks — (See Chapter 8, Lateral Stability section for techniques to assess lateral
stability).
4. Natural features such as point bars may be present, but without excessive bar develop-
ment, like mid-channel or transverse bars.
5. Same stream type as the project reach after restoration (i.e., C4, E5, etc.).
6. Same valley type and approximate slope as study reach.
7. Same bed material as study reach (i.e., sand, gravel, cobble, bedrock, etc.).
8. Same type of bank vegetation as the project reach (e.g., do not use a mature bottom
land hardwood forest reference reach for a restoration project that will only include a
herbaceous buffer).
In order to select an appropriate reference reach, several tools are used in support of
the identification process:
A Function-Based Framework » May 2012 74
-------
Chapter 5: Reference Streams
1. US Geological Survey Quadrangle Maps: Quadrangle maps can be used to identify
streams of a particular watershed size, valley type and slope. Quadrangle maps also
provide general information on watershed conditions and land use, although these
data should be checked against other more recent data sources (such as aerial photo-
graphs), since quadrangle maps are not updated very frequently.
2. Aerial Photographs: Aerial photographs can be very useful in identifying potential
reference reaches and further evaluating reference reaches identified by other maps,
such as from a USGS quadrangle map. Evaluating multiple aerial photographs over
time can provide additional support regarding stream stability by documenting stream
dimension and pattern before and after flood events.
3. Windshield Surveys: Many reference reach sites have been identified by simply driving
and looking at streams upstream or downstream of roadway crossings. Ensure that
landowner permission to access the stream is obtained before entering private property.
4. Discussions with Local Residents: Landowners and local residents are often very
familiar with their land and the land that is nearby. These resources can often be used to
identify streams that are in good condition and may potentially serve as a reference reach.
5. Looking Upstream and Downstream of the Project Reach: When available, this is one
of the best sources for reference reach data, because the reference reach and impaired
reach targeted for restoration share the same climatic, topographic and watershed
conditions. As with windshield surveys, ensure that landowner permission to access
the stream is obtained before entering private property.
6. Existing Watershed and Stream Assessment Reports and Reference Reach Databases:
Many agencies and organizations have produced assessment reports that identify
stable and unstable stream reaches. These reports are an excellent source as an initial
step in identifying potential reference reaches. Furthermore, some of these agencies
and organizations have already developed reference reach databases that are available
to the public.
7. Discussions with Environmental Professionals: There are many environmental profes-
sionals who, as part of the jobs, are required to walk many stream miles. These folks
can provide expert opinions on the location of potential reference sites.
In urban and other highly altered environments, it is often difficult to identify true
reference reach sites that meet the criteria above. Often, urban streams have been highly
modified, either by direct manipulation or through modified hydrology from increased
impervious surface runoff. While it is often difficult to identify a stable urban reference
reach, it is not uncommon to find short segments of stable urban channel that can be used
to evaluate stable bankfull dimensions. Such a stream segment is ideally located just
upstream or downstream of the study reach, allowing for direct correlations to proper
bankfull dimensions for the design. Finding an applicable reach can be a time-consuming
process, and a thorough investigation should be completed to ensure a suitable reference
reach is located.
A Function-Based Framework » May 2012 75
-------
Chapter 5: Reference Streams
Physicochemical and Biology Reference Reaches (Levels 4-5)
Selecting reference streams that represent high-quality Physicochemical and Biology
functions is similar to selecting sites for Geomorphology functions (Levels 1-3) with one
large exception. It is possible to have a stable channel with proper bed form diversity in a
watershed with point and non-point sources of pollution. However, reference streams
used to determine the reference condition for Physicochemical and Biology functions
require a healthy upstream watershed with limited point and non-point sources of pollution.
Therefore, additional site selection criteria are needed. Additional recommended criteria
for reference streams used for Physicochemical and Biology functions are provided below:
1. Most of the watershed is at the natural climax vegetative community, e.g., forested,
scrub shrub, grassland.
2. Adequate/comparable flow duration for species of interest.
3. No point sources of pollution (preferable) or point sources that have not impacted
aquatic life.
In addition to the tools provided for the Geomorphology section above, the tools listed
below may be helpful in identifying Physicochemical and Biology reference reach streams.
1. Choose from state designated sites. Most state water protection agencies have desig-
nated hundreds of reference sites based on robust region-specific reference site criteria
for assessing aquatic-life use attainment.
2. Check water quality designations. Investigate state water quality designation lists and
look for High Quality Waters (HQW), Outstanding Resources Waters (ORW) or
similar designations.
3. Search on public land. Look for reference streams in national/state parks, national/
state forests and designated wilderness areas.
Many of these streams will not be pristine due to historical impacts; however, they
may represent the highest level of functionality that is achievable. This is an important
consideration when selecting a site for Physicochemical and Biology functions. Some
projects may strive to restore functions to a pre-disturbance, pre-European settlement
condition — a worthy, but very difficult goal. Most projects try to restore functions to the
highest level possible given the constraints of human development. If so, a reference
stream should be selected that reflects this condition, i.e., healthy but not pristine. This is
one of the most difficult and controversial issues related to determining the reference
condition. Stoddard et al. (2006) and Miller et al. (2011) provide guidance for determining
the reference condition type, e.g., historical condition, best attainable condition, and refer-
ence condition approach that may best fit with geographic constraints and legacy impacts.
5.4 » ASSESSING REFERENCE REACHES
There are dozens of ways to assess reference reaches, many of which can also be used
to assess impaired reaches. However, assessment methods vary greatly in what and how
they assess stream functions. Some methods are rapid and others are very time intensive
A Function-Based Framework » May 2012 76
-------
Chapter 5: Reference Streams
and costly. Some methods focus on physical
functions and others focus on biological
functions; few assess all functions. Therefore,
it is critically important to know the reason
for conducting a reference reach assessment
prior to the assessment or survey. Having
clear project goals and objectives will serve as
an aid in selecting the proper type of refer-
ence reach.
Building on the discussion above about the
uses of reference reach streams, the following
list of assessment methods is provided for
Hydrology, Hydraulic and Geomorphology
references (Levels 1-3), and assessment
methods that focus on Physicochemical and/
or Biology conditions (Levels 4-5). The title
of the assessment method, a brief description
and Web link to the source document is
provided. Refer to Somerville and Pruitt
(2004) and Somerville (2010) for a description
of additional assessment methodologies.
These reports can be downloaded, respec-
tively, from the EPA website at: water.epa.gov/
lawsregs/guidance/wetlands/up-
However, assessment meth-
ods vary greatly in what and
how they assess stream func-
tions. Some methods are
rapid and others are very
time intensive and costly.
Some methods focus on
physical functions and others
focus on biological functions;
few assess all functions.
Therefore, it is critically im-
portant to know the reason
for conducting a reference
reach assessment prior to the
assessment or survey. Having
clear project goals and objec-
tives will serve as an aid in
selecting the proper type of
reference reach.
load/2004_ 09_01_ wetlands_ PhysicalStreamAs-
sessmentSep2004Final.pdfand water.epa.gov/lawsregs/guidance/wetlands/upload/Stream-
Protocols_2010.pdf. USAGE is currently developing reference assessment approaches for
reference stream condition built upon their Hydrogeomorphic (HGM) Approach that was
initially applied to wetlands. The approach has been applied to intermittent streams in
the Appalachian region (USAGE, 2010), but not to perennial streams at this time. Pruitt et
al. (2012) further describes a proposed Reference Condition Index (RCI) that could be
used to guide the application of reference condition to an assessment of environmental
benefits in aquatic ecosystems.
Pyramid Level 1-3 Methods for Assessing Reference Stream Condition
The following list highlights assessment methods that focus on Pyramid Level 1-3 functions.
Therefore, these methods are more physically based than biological. Some are used more
for natural channel design and others for assessing sediment supply and channel stability.
Title: Stream Channel Reference Sites: An Illustrated Guide to Field Technique
Description: Provides basic overview of surveying procedures (differential leveling) for
channel cross sections and profiles. Also provides methods for conducting pebble counts,
A Function-Based Framework » May 2012
77
-------
Chapter 5: Reference Streams
staff gauge installation, discharge measurements and pebble count procedures.
Link: www.stream.fs.fed.us/publications/PDFs/RM245E.PDF
Title: The Reference Reach — A Blueprint for Natural Channel Design
Description: A Proceeding paper that describes the Rosgen method for collecting and
using reference reach survey data. Primarily used for natural channel design and compar-
ing the geomorphology of reference streams to impaired streams.
Link: www.wildlandhydrology.com/assets/The_Reference_Reach_ll.pdf
Title: Rosgen Geomorphic Channel Design
Description: Part 654, Chapter 11 in the NRCS Stream Restoration Design National
Engineering Handbook. Provides a detailed description of how these reference reaches are
used in natural channel design processes.
Link: directives.sc.egov.usda.gov/viewerFS.aspx?id=3491
Title: Proper Functioning Condition
Description: A rapid qualitative approach that uses a checklist to determine channel and
riparian condition. Checklist includes questions about hydrology, vegetation and erosion/
deposition. The final result places the stream into one of three categories: Proper Func-
tioning Condition, Functional-at-Risk and Nonfunctional.
Link: ftp.blm.gov/pub/nstc/techrefs/Final%20TF! %201737-9.pdf
Title: Watershed Assessment of River Stability and Sediment Supply
Description: A geomorphological approach for quantifying the effects of land uses on
sediment supply and channel stability. Provides sub-watershed rankings and prioritizes
stream reaches based on broad-level screening approaches, but also provides more de-
tailed assessment procedures.
Link: water.epa.gov/scitech/datait/tools/warsss/index.cfm
Title: Size Class Pebble Count Analyzer
Description: A spreadsheet tool that is used to identify shifts in the fine gravel and
smaller portions of the grain size distribution, rather than the median. It can be used to
compare grain size distributions at an impaired site and determine if the distribution is
statistically different than a reference site. It can also be used for before and after restora-
tion comparisons.
Link: www.stream.fs.fed.us/publications/software.html
Title: Channel Evolution Models/Stream Type Succession Scenarios
Description: These two methodologies illustrate how streams evolve after a disturbance.
They would rarely be used as a standalone assessment method, but are a valuable addi-
tion to most other assessment methodologies. A reference stream would typically func-
tion at an evolutionary endpoint; however, an impaired stream may be moving towards
A Function-Based Framework » May 2012 78
-------
Chapter 5: Reference Streams
or away from a reference condition.
Link: Simon Channel Evolution Model: www.nrcs.usda.gov/wps/portal/nrcs/detailfull/
national/technical/alphabetical/water/restoration/?&cid=stelprdbW43448 (Chapter 7)
Link: Rosgen Stream Type Succession Scenarios: water.epa.gov/scitech/datait/tools/warsss/
successn.cfm
Title: Regional Curves
Description: Many of the assessment methodologies used to evaluate Pyramid Level 1-3
functions require an estimate of the bankfull discharge and corresponding stage. Regional
curves, while not an assessment methodology, are excellent tools for validating field
estimates of the bankfull stage.
Link: water. epa.gov/lawsregs/guidance/wetlands/upload/Appendix-A_ Regional_ Curves.pdf
Pyramid Level 4-5 Methods for Assessing Reference Stream Condition
A wide variety of stream assessment protocols that focus on Physicochemical and
Biology functions are available, probably more than for the Hydrology, Hydraulic and
Geomorphology functions. Since both of these functions vary greatly across the country,
most state water quality programs have developed their own assessment methods.
However, many of these are based on the Rapid Bioassessment Protocol or Index of Biotic
Integrity that are discussed below. Like the discussion above about assessing the reference
condition of Pyramid Level 1-3 functions, selecting the correct reference reach assessment
method for Pyramid Levels 4-5 will depend on the project goals and objectives. Some of
the more common assessment methods are listed below; however, many projects may
require a tailored approach.
Title: EPA Rapid Bio-assessment Protocol (RBP)
Description: A rapid assessment method that provides basic aquatic life data for water
quality management purposes such as problem screening, site ranking and trend monitor-
ing. The RBPs are a synthesis of existing methods from state water resource agencies and
include three aquatic assemblages (periphyton, benthic macroinvertebrates, fish) and
habitat assessment methodologies.
Link: water.epa.gov/scitech/monitoring/rsl/bioassessment/index.cfm
Title: Index of Biotic Integrity (IBI)
Description: The original version included 12 metrics that were used to evaluate stream
health based on fish data. The metrics and scoring have been modified over time and
expanded to include an IBI for macroinvertebrates.
Link: www.epa.gov/bioiweb1/html/ibi_history.html
Title: NRCS Stream Visual Assessment Protocol
Description: A simple assessment of stream condition that includes qualitative observa-
tions of Pyramid Level 1-5 parameters. It is intended to be a first approximation of stream
A Function-Based Framework » May 2012 79
-------
Chapter 5: Reference Streams
condition rather than an intensive assessment of stream function.
Link: www.nrcs.usda.gov/wps/portal/nrcs/detailfull/national/technical/alphabetical/water/rest
oration/7 & cid=stelprdb 1043249
Title: Monitoring Wilderness Stream Ecosystems
Description: This document is a manual that presents a protocol for monitoring a variety
of Pyramid Level 1-5 parameters and includes measures of structure and function. The
document also includes guidance on setting monitoring goals and objectives, selecting
sampling location and analyzing data.
Link: www.fs.fed.us/rm/pubs/rmrs_gtr70.pdf
Title: US 301 Environmental Stewardship Study
Description: The US 301 Environmental Stewardship Study is a green infrastructure
study that included a stream assessment component. The stream assessment component
consists of a GIS-based course stream stability assessment and a rapid stream habitat and
stability assessment and restoration feasibility methods. The rapid assessment methods
provide a numerical score which can be used for ranking and prioritization purposes.
Link: www.fws.gov/chesapeakebay/streampub.html
5.5 » MONITORING APPROACHES
The above methodologies can be used to assess reference streams that can then be
used as a comparison against an impaired stream. However, it is important that reference
streams are in the same hydro-physiographic region and ecoregion as the project site for
Physicochemical and Biology function assessments. In addition, some reference reach and
project reach assessments may need to focus on a few select parameters, rather than an
overall assessment of channel condition or function that is typically provided by "canned"
methodologies. For example, one project may have a goal to increase the grain size
distribution in a gravel bed stream to refer-
The above methodologies Can ence conditions. Another project may want
be used to assess reference to imProve dissolved oxy§en> temperature
and nutrient levels to reference conditions.
Streams that Can then be 7nere are two common monitoring ap-
t/Sec/ as a Comparison against preaches that can be used to help show
an impaired Stream. However, statistical differences in a project reach
.... , versus a reference reach: upstream/down-
it is important that reference A A / ,
stream and paired watershed monitoring.
Streams are in the Same However, determining the correct statistical
hydro-physiographic region approach to use within these two sampling
and ecoregion as the project regimes is critical and should often be
provided by a trained statistician. The EPA
Site for PhySICOChemiCal and provides a statistical primer with a variety
Biology function assessments, of examples at http://www.epa.gov/bioindica-
A Function-Based Framework » May 2012 80
-------
Chapter 5: Reference Streams
tors/statprimer/statistical_testing.html. USEPA (1997a) also provides instruction on how to
statistically evaluate the effectiveness of best management practices, like stream restora-
tion, on improving water quality.
Upstream/Downstream Monitoring
The ideal scenario for performance standards that use reference reach data is for the
reference reach to be located upstream of the project reach. This makes it much easier to
have a goal of restoring a project reach to a reference condition. The parameters and
measurement methods are selected, again based on project goals and the potential to
restore those functions. The monitoring must occur upstream of the project reach and
downstream of the project reach and before and after restoration, lasting long enough to
complete the statistical analysis. The purpose in this approach is to show that, over time,
the downstream monitoring station becomes statistically similar to the upstream moni-
toring station. Upstream/downstream monitoring can also be used if the reach upstream
of the project is not of reference condition. However, in this case, it is more likely that the
project will show improvements to Pyramid Level 3 parameters like lateral stability
(sediment supply from bank erosion) than to Pyramid Level 5 parameters like macroin-
vertebrate communities.
Paired Watershed Monitoring
If a reference stream cannot be found upstream of the project reach, a paired water-
shed approach may be practical, especially for small headwater catchments. This moni-
toring approach compares monitoring/assessment results from a stable watershed to the
impaired watershed. However, for this approach to work, the stable watershed must
remain stable throughout the life of the project. Both sites must be monitored before and
after restoration for a long enough time to show statistical differences. The Size Class
Pebble Count Analyzer discussed above under Pyramid Level 1-3 Method for Assessing
Reference Condition provides an example of using a paired watershed approach.
Monitoring Guidance for Determining the Effectiveness ofNonpoint Source Controls (USEPA,
1997a) is a good resource for designing monitoring plans that use statistical techniques to
show that stream improvements were caused by a best management practice, in this case
stream restoration.
A Function-Based Framework » May 2012 81
-------
3.QG iniGniioricuiy LGTI t5i3.riK
A Function-Based Framework » May 2012 82
-------
Chapter 6
Hydrology
The study of hydrology, especially by engineers, quantifies the transport of water that
is contributed from the watershed and delivered to a stream channel. Hydrology func-
tions are the base of the Stream Functions Pyramid (Level 1) and therefore support all
other functions. Common ways to assess and quantify this hydrologic function include
channel-forming discharge, precipitation/runoff relationships, flood frequency and flow
duration. Table 6.1 provides a list of parameters discussed in this chapter along with the
measurement methods. There are other measures of Hydrology; however, the ones
provided here are most closely associated with stream assessment and restoration tech-
niques. Appendix Ac includes a list of all the Hydrology measurement methods along
with information about the method's type, level of effort, level of complexity, and wheth-
er it is a direct or indirect measure of the function-based parameter. The criteria used to
make these determinations are provided in Chapter 4.
TABLE 6.1 HYDROLOGY PARAMETERS, MEASUREMENT METHODS AND AVAILABILITY OF
PERFORMANCE STANDARDS
PARAMETER
Channel-Forming Discharge
Precipitation/Runoff Relationship
Flood Frequency
Flow Duration
MEASUREMENT METHOD
1. Regional Curves
1. Rational Method
2. HEC-HMS
3. USGS Regional Regression
Equations
1. Bulletin 17b
1. Flow Duration Curve
2. Crest Gage
3. Monitoring Devices
4. Rapid Indicators
PERFORMANCE
STANDARD
No
No
No
No
No
No
No
No
No
For most stream restoration projects, Hydrology parameters are independent variables,
meaning that the restoration practitioner cannot change them as part of the design
process. They are primarily used to characterize the watershed and as input parameters
for Hydraulic assessments; therefore, the Hydraulics Chapter in this document discusses
their importance and associated performance standards. There can be exceptions, how-
A Function-Based Framework » May 2012
83
-------
Chapter 6: Hydrology, Channel-Forming Discharge
ever, especially if the stream restoration project is part of a larger watershed management
plan. It may be possible to use stormwater BMPs, or other practices to reduce runoff. In
these cases, a performance standard could be established for the reduction in runoff.
Other scenarios include highly modified headwater systems, such as impacts associated
with mining through springs and headwater streams. Here, restoring flow duration is a
critical component of the restoration project and should include the development of
performance standards. Hydrology parameters are included even without performance
standards because of their importance in supporting the higher-level functions. Without
an assessment of these parameters, many of the higher-level computations cannot be
completed; therefore, it would be remiss to not include them.
6.1 » PARAMETER: CHANNEL-FORMING DISCHARGE
Description
Channel-forming discharge theory suggests that a unique flow over an extended
period of time would yield the same channel morphology that is shaped by the natural
sequence of flows. Inglis (1947) stated that at this discharge, equilibrium is most closely
approached and the tendency to change is least. This condition may be regarded as the
integrated effect of all varying conditions over a long period of time. Channel-forming
discharge theory is often described as dominant discharge, effective discharge and the
bankfull discharge (Knighton, 1998). Dominant discharge is simply a synonym for
channel-forming discharge theory. Effective discharge is the product of the flow duration
curve and the sediment transport rating curve; therefore, it is the discharge that moves
the most sediment over time and is a key parameter in determining channel size (Wol-
man and Miller, 1960). Bankfull discharge fills a stream channel to the elevation of the
active floodplain, thereby delineating the break between erosional (channel forming) and
depositional features in a floodplain (Dunne and Leopold, 1978; FISRWG, 1998). Since
this discharge leaves a geomorphic indicator, it has become the method used most often
to describe channel-forming discharge theory. It is also the design discharge for natural
channel designs.
Measurement Method
1. Regional Curves
The identification of bankfull stage and its associated dimensions and discharge are
often used in stream assessment and restoration projects using natural channel design
techniques. The identification of the bankfull stage is one of the first measurements made
during a geomorphic assessment because the Rosgen stream classification system and
stability assessments (vertical and lateral) are all dependent on knowing the bankfull
stage. In addition, many of the Hydraulic and Geomorphic parameters, such as floodplain
connectivity, are dependent on being able to identify and verify the bankfull stage and its
corresponding dimensions (especially cross-sectional area). There are several documents
that discuss how to field identify and verify bankfull. Rosgen (2006), as part of the
Watershed Assessment of River Stability and Sediment Supply (WARSSS), provides a
A Function-Based Framework » May 2012 84
-------
Chapter 6: Hydrology, Channel-Forming Discharge
detailed description of field methods for identifying and calibrating the bankfull stage.
(WARSSS is available on the EPA website at www.epa.gov/warsss.) Harrelson et al. (1994)
provides a more concise summary of field methods for identifying bankfull (www.stream.
fs.fed.us/publications/PDFs/RM245E.PDF). Harman (2000) provides methods for identifying
bankfull in North Carolina streams, which also include a detailed description of how to
measure and calculate the bankfull cross-sectional area (www.bae.ncsu.edu/programs/
extension/wqg/srp/rv-crs-3.pdf).
All of these references rely on regional curves as the primary method for verifying the
bankfull stage. These curves are tools that can be used to verify the bankfull stage in
projects prior to restoration, as a design aid and as a tool for assessing performance.
Regional curves relate bankfull discharge and channel dimensions (i.e., width, depth and
cross-sectional area) to drainage area. (See Figure 6.1 for an example regional curve.)
Regional curves are empirically derived, primarily from USGS gauge stations, and can be
developed for a single watershed or multiple watersheds in the same hydro-physiographic
region (FISRWG, 1998). Developing watershed-specific regional curves requires a moder-
ate level of effort; however, developing regional curves for an entire physiographic region
is an intensive level of effort. If existing regional curves are used, then the level of effort
required to use the curve is considered rapid. Likewise, using an existing regional curve is
not complex and is categorized as simple in Appendix Ac; however, developing a regional
curve is complex, requiring experience and expertise.
Regional curves were first developed by Dunne and Leopold (1978). In recent years,
regional curves have been developed across many regions to assist in geomorphic assess-
ments and natural channel design (Cinotto, 2003; Keaton et al., 2005; Miller and Davis,
2003; Harman et al., 1999; Harman et al., 2000; McCandless and Everett, 2002; McCand-
less, 2003a and 2003b; Sweet and Geratz, 2003; Castro and Jackson, 2001; Chaplin, 2005;
Doll et al., 2002; Dudley, 2004; Dutnell, 2000; Mulvihill et al., 2005; and Metcalf, 2004).
Somerville (2010) provides a comprehensive list of regional curves published throughout
the United States.
When using existing regional curves, care should be taken to determine that the
regional curves are appropriate for the project site, i.e., that they are in the same hydro-
physiographic region and that the curves were created through unbiased surveys of
bankfull indicators. The dimensions (area, width and depth) should come from cross-
sectional surveys taken at stable riffles. There have been cases where the 1.5-year return
interval was used as bankfull, rather than a physical assessment of the geomorphic
indicator. There are other cases where the terrace was used as the bankfull stage, which
often results in a return interval that is greater than two.
A Function-Based Framework » May 2012 85
-------
Chapter 6: Hydrology, Channel-Forming Discharge
FIGURE 6.1 REGIONAL CURVE EXAMPLE
North Carolina Mountain Regional Curve (Harman et alv 2000) overlaid with a watershed specific
curve within the same region. The blue line is lower because it is in a region of the mountains with
lower rainfall. The red line represents the entire mountain region ofNC, including high and low
rainfall areas. Note that while the magnitude of the cross-sectional area is different between the two
curves, the slope of the two lines is similar.
1000 n
E
w 100
•
I
u
•
W
x 10
B
03
•
• \
f
\
m
\\
SIC Mountain Regional Curve data b
>tal.,(2000)
Watershed Specific Regional Curve
rom Michael Baker Corporation
SIC Mountain Regional Curve regre
A/atershed Specific Regional Curve
egression line
y Harman
data
ssion line
.-*""
.^ -^
^"^
^^
-— i
•"i
*
,»-
*»
*,
»
-------
Chapter 6: Hydrology, Precipitation/Runoff Relationship
performance standards based solely on the bankfull discharge. An example of a project
that used a design discharge that was less than the bankfull discharge is shown below in
Figure 6.2. The result is a channel that is much smaller than a typical channel size de-
signed using the bankfull discharge (Art Parola, 2011, personal communication).
FIGURE 6.2
Photos of a project near Lexington, KY that was sized using a discharge smaller than the bankfull
discharge. The channel has remained stable after numerous floods. Flow duration has significantly
improved due to improved groundwater/surface water interaction, converting an intermittent channel
into a perennial channel. This approach works because, among other things, the sediment supply is
fairly low, grade control is used in the channel and beneath the floodplain, and vegetation is allowed
to establish before the stream flow is moved to the new channel. This approach should not be used in
streams with a large sediment load that must be transported through the reach.
Photo by Will Harman
6.2 » PARAMETER: PRECIPITATION/RUNOFF RELATIONSHIP
Description
The amount of precipitation that does not soak into the ground and instead "runs off"
the ground surface is a critical component in determining the size of a stream channel.
Regions that have high precipitation and runoff (precipitation/runoff) rates often have
larger channels than areas with lower precipitation/runoff rates. In humid areas like the
Southeastern United States, perennial channels form in watersheds with drainage areas
considerably less than one-half of a square mile. In arid regions, however, ephemeral
channels exist in watersheds with drainage areas that are hundreds of square miles. This
has a major effect on functions in Pyramid Levels 4 and 5.
The effect of precipitation/runoff variability can be seen in comparisons of regional
curves of bankfull discharge and cross-sectional area versus drainage area. Regional
curves are power function regression equations. Regions with higher precipitation/runoff
rates have higher y-intercept values than regions with lower precipitation/runoff relation-
A Function-Based Framework » May 2012
87
-------
Chapter 6: Hydrology, Precipitation/Runoff Relationship
ships; however, the slope of the regression line for all these curves is remarkably consis-
tent. In other words, while the processes that create channel shape and size are similar
across regions, variations in the precipitation/runoff relationship create different size
channels. An example of this is shown above in Figure 6.1.
Measurement Method
1. Rational Method
The most rapid and simplest method for calculating runoff is the Rational Method or
Rational Equation, which is used to estimate peak runoff in small drainage basins. This
equation uses a runoff coefficient (C) that is taken from a table, like the one published by
the American Society of Civil Engineers (1970) and is most suited for watersheds with a
drainage area less than 250 acres. The Rational Equation shows that if it rains long
enough, the peak discharge from the drainage area will be the average rate of rainfall
times the drainage basin area, which is then reduced by multiplying by the runoff coef-
ficient. The time of concentration is the length of time that it takes water to flow from
the beginning of the watershed to the point where runoff (discharge) occurs (Fetter,
1994). The Rational equation is:
Qp = CiA, where
Qp = the peak runoff rate in cubic feet per second.
C = the runoff coefficient
i = the average rainfall intensity in inches/hour, and
A = the size of the drainage in acres.
The Rational Method has evolved through time with the use of computer models. The
Natural Resources Conservation Service (NRCS) has developed two computer models that
are based on the Rational Method: WinTRSS and WinTR20 (USDA, 2009a and 2009b).
These models have been used extensively to design small farm ponds and even large flood
control reservoirs. Since it is better to build a dam that is slightly too large rather than
one that is too small, these models often give conservatively high estimates of runoff.
2. HEC-HMS
The USAGE Hydrologic Engineering Center has developed a more sophisticated and
complex model called the Hydrologic Modeling System (HEC-HMS). This model simu-
lates precipitation and runoff processes from a wide range of dendritic watersheds, in-
cluding small and large watersheds, as well as rural and urban conditions. More informa-
tion and a free download of the software can be found at the HEC-HMS website (www.
hec.usace.army.mil/software/hec-hms). However, only experienced hydrologists should use
the model.
3. USGS Regional Regression Equations
The United States Geological Survey (USGS) uses their network of gauging stations to
provide "regional regression equations" that typically estimate discharge for the 2-, 5-,
A Function-Based Framework » May 2012 88
-------
Chapter 6: Hydrology, Flood Frequency
10-, 25-, 50- and 100-year flood events. These empirical relationships are often developed
for each physiographic region and stratified by rural and urban basins. The results are
published in reports, often by state, that can be obtained from the USGS website (water.
usgs.gov/software/NFF). Since the return interval for the bankfull discharge is less than
the 2-year return interval, regional regression equations from the 1-to 2-year range are
needed for stream restoration applications. The USGS in West Virginia has prepared
regional regression equations from the 1.0- to 3.0-year range. In addition, they created
equations in 0.1-year increments, from the 1.0- to 2-year return interval, e.g., 1.1, 1.2, etc.
(Wiley et al., 2002). Ideally, more curves for these lower return intervals will be devel-
oped for other regions.
Design Standard
The precipitation/runoff relationship is an important variable in determining channel
size and is a vital part of the design process. It was mentioned that the discharge pro-
duced by the watershed is often an independent variable in the natural channel design,
with the exception of watershed scale projects that might reduce runoff through storm-
water BMPs. Therefore, there isn't a performance standard associated with this param-
eter. A natural channel should carry the appropriate amount of water to maintain dy-
namic equilibrium and appropriate streambed formations. However, channels that are
designed to carry larger storm events, such as the 100-year event, would not function as a
natural channel. This type of performance can be assessed below in the Hydraulic Chap-
ter under Floodplain Connectivity.
6.3 » PARAMETER: FLOOD FREQUENCY
Description
Flooding is the periodic, natural occurrence of high flows that exceed the depth of the
channel. Flood frequency defines the magnitude and frequency of a given flood and is
often analyzed as part of the precipitation/runoff analysis described above. However,
these parameters are sometimes assessed for different reasons because "flooding" is
defined differently by different disciplines. For example, the geomorphologist defines
flooding as the flow that leaves the channel and spreads onto a floodplain that was built
by a meandering river, sometimes called a geomorphic floodplain. A traditional water
resources engineer might define flooding as the flow that would impact personal property,
such as a home. In both cases, flood frequency can be used to predict the probability that
a flow will reach a certain elevation (active floodplain or house) within a given timeframe.
The geomorphologist typically associates the flood frequency of the active floodplain as
the discharge with a 1.5-year return interval (on average). The water resources engineer
typically delineates floodplains by the elevation of the 100-year return interval discharge.
These two return intervals can also be expressed as an exceedence probability, which is
simply the reciprocal of the return interval. Therefore, in the case of the 1.5- and 100-
year return intervals, the exceedence probabilities are 67% and 1%, respectively.
While the smaller floods are important for channel formation and maintenance, large
A Function-Based Framework » May 2012 89
-------
Chapter 6: Hydrology, Flood Frequency
floods are important geomorphic agents as well. They are important in developed areas
because large floods can damage homes, roads and other structures. For stream restora-
tion projects, it is typically most important to know the flood frequency of the bankfull
discharge and the 100-year flood event. It is important to know the frequency of bankfull
to help ensure that the channel is not carrying more water than is necessary to maintain
dynamic equilibrium. In addition, many stream restoration projects are located in Federal
Emergency Management Agency (FEMA) regulated floodplains. In these cases, a no-rise
certification is required to show that the project is not increasing the 100-year flood
elevation. If the project is designed to increase flooding, and it is acceptable to the land-
owner, a Letter of Map Revision will be required. More information about working in
FEMA regulated floodplains can be found at: www.msc.fema.gov.
Measurement Method
1. Bulletin 17b
The standard for estimating flood frequency in the United States is published by USGS
(1981) in Bulletin 17b (water.usgs.gov/osw/bulletinUb/bulletin_UB.html). The most common
method for estimating flood frequency is the Log-Pearson Type III distribution, which is
also described in the bulletin. This method uses the annual peak discharge over many
years to calculate the probability of occurrence. The technique is complex and should be
performed by experienced hydrologists. However, for most regions of the United States,
flood frequency analysis has already been completed and can be downloaded by state
from the USGS website.
Some areas of the country are starting to use partial duration analysis to determine
the flood frequency of bankfull. This technique is often preferred over Log Pearson
because it uses more data points per year than the single peak discharge used by Log
Pearson. Partial duration analysis sets a discharge of interest and then includes all the
discharges that exceed that value. Therefore, gauge stations with continuous data are
required for this analysis.
Design Standard
Flood frequency analysis is often performed in conjunction with the precipitation/
runoff analysis. For flood control projects, a flood discharge with a certain return interval,
e.g., the 100-year or 1% probability storm event, is used as the design discharge. A channel
size is then designed to carry the 100-year discharge. In natural channel design, however,
the channel is sized to carry the bankfull discharge. Methods to determine the bankfull
discharge are described above, but the return interval for bankfull is only used as a guide.
As mentioned before, the average is 1.5 years and the range is from 1 to 2 years. This
range can be used as a guide to develop performance standards, along with other param-
eters like floodplain connectivity. Therefore, the specific performance ranges for Func-
tioning, Functioning-at-Risk and Not Functioning are described in the Hydraulics Chapter.
A Function-Based Framework » May 2012 90
-------
Chapter 6: Hydrology, Flow Duration
6.4 » PARAMETER: FLOW DURATION
Description
Flow duration is the percentage of time that a discharge is above or below a given
value. It is often expressed as a flow duration curve that plots discharge on the y-axis and
probability (percent of time) on the x-axis. In some parts of the country, especially the
West, improving flow duration is an important stream restoration goal. It is also an
important functional goal for stream restoration after landscape alterations, such as
surface mining through streams.
When flows are critical to maintain a particular species of fish, mussel or macroinver-
tebrate, flow duration curves can allow one to denote the percent of time a river will
exceed that critical value. Alternatively, flow duration curves can be used to determine
the discharge that occurs a certain percentage of time. Flow duration can also be general-
ized to focus on the simple presence versus absence of flow over time — in other words,
perennial, intermittent or ephemeral streams. For most projects perennial, intermittent or
ephemeral flow will be an independent variable. For more specific information on the
importance of flow duration, see Dahm et al. (2003), Humphries and Baldwin (2003), and
Stromberg et al. (2007).
Measurement Method
1. Flow Duration Curve
Long-term records from gauge stations are needed in order to develop flow duration
curves. From the historical records, the data are ranked in order from highest to lowest.
The probability that a discharge can be equaled or exceeded can be calculated as follows:
P= 100 M/(n+l), where
P = the probability that a flow will be equaled or exceeded (% of time)
M = the ranked position of the peak discharge values (dimensionless)
n = the number of peak discharge values in the record (dimensionless).
The discharge and corresponding probability are then plotted on probability paper. A
step-by-step example of how to create a flow duration curve is provided by Watson and
Burnett (1993). An example of a flow duration curve is shown in Figure 6.3. If gauge data
are not available, computer models like HEC-HMS can be used to predict a flow duration
curve using information from the closest gauge.
A Function-Based Framework » May 2012 91
-------
Chapter 6: Hydrology, Flow Duration
FIGURE 6.3 FLOW DURATION CURVE EXAMPLE
1000
900
10
30
40 50 60
Probability (Percent of Time)
70
80
90
100
Source: Adapted from original graph by Michael Baker Corporation
Flow duration can also be directly measured at the project site. For perennial streams
and large intermittent and ephemeral channels, a gauge station can be established with
an automatic stage recorder. These recorders will measure stage and time. A stage/dis-
charge relationship would have to be developed in order to plot discharge. Dingman
(2008) provides instructions on how to establish a stream gauge for short-term studies.
For this reason, the level of effort can range from moderate (for modeling) to intensive
(for measuring flow over time). The level of complexity can also vary; however, it is often
more complex to model flow duration than to measure flow duration. A measured flow
duration curve is a direct measure of the flow duration function-based parameter; where-
as, a modeled curve is an indirect measure (Appendix Ac).
2. Crest Gauge
A simpler and more common approach is to establish a crest gauge at the project site. A
crest gauge records the highest elevation of the peak flow, usually without electronic
instrumentation. A crest gauge does not provide information about the duration of the
peak flow; however, it will provide information about flow occurring between site visits.
Crest gauges are most often used in stream restoration projects to determine if bankfull
A Function-Based Framework » May 2012
92
-------
Chapter 6: Hydrology, Flow Duration
events occurred between monitoring surveys. Harrelson et al. (1994) provides a simple
description of how to build a crest gauge.
3. Monitoring Devices
A monitoring device developed by Flowline Products is being used on small ephemeral
and intermittent drainages in the Coastal Plain of North Carolina to document the
duration and relative magnitude of flow events. The device is based on the principles of a
variable area flow measurement, and consists of a vertical baffle mounted on an axis
inside a protective housing. Flow passing through the housing causes the baffle to tilt on
its axis, and the degree of tilt is recorded by the internal electronics and logging device.
The device is capable of recording flows as low as 0.5 gal/min (Tweedy, 2010, personal
communication). Other monitoring devices are also available and can be used for a
variety of conditions (Blasch et al., 2002; Adams et al., 2004; Goulsbra et al., 2009; Fritz
etal.,2006).
4. Rapid Indicators
Measuring general flow duration rapidly in the field on a non-gauged stream, whether
the stream is perennial, intermittent or ephemeral, can be done using indicators of flow
duration. Specific indicator-based methods have been developed by the North Carolina
Department of the Environment and Natural Resources; EPA Region 10, Oregon Depart-
ment of State Lands and the Portland Corps District; New Mexico Environment Depart-
ment; and others that are currently under consideration. Links to select manuals are
provided below.
North Carolina Department of Environment and Natural Resources, Division of Water
Quality. Raleigh, NC. V.4. portal.ncdenr.org/web/wq/swp/ws/401/waterresources/streamde-
terminations)
Oregon Streamflow Duration Assessment Method Interim Version, Public Notice
release date, 6 March 2009. www.oregonstatelands.us/DSL/PERMITS/docs/osdam_
march_2009.pdf?ga=t
New Mexico Environment Department/Surface of Water Quality Bureau (NMED/
SWOB) Hydrology Protocol for the Determination of Ephemeral, Intermittent, and
Perennial Waters — DRAFT. Released August 2009. ftp.nmenv.state.nm.us/www/swqb/
MAS/Hydmlogy/NMHydmPmtocol-PublicCommentDraft08-2009.pdf
Performance Standards
Performance standards for flow duration will be unique to every stream. Therefore,
functional categories are not assigned to this parameter. However, local practitioners can
develop performance standards based on flow needs of fish, mussels or other needs. For
stream restoration projects on highly manipulated sites, such as surface mining, restoring
the general flow duration may be used as a performance standard to help ensure that the
suite of functions lost is being replaced.
A Function-Based Framework » May 2012 93
-------
3.QG iniGniioricuiy LGTI t5i3.riK
A Function-Based Framework » May 2012 94
-------
Hydraulics
Hydraulic functions transport water in the channel, on the floodplain and through
sediments. Fischenich (2006) describes these functions as surface water storage processes,
maintenance of surface and subsurface connections and processes, and the general hydro-
dynamic balance, which describes the flow conditions in the channel and on the flood-
plain throughout the year. Here, three broad-level parameters are used to describe the
Hydraulic functions. These include floodplain connectivity, flow dynamics and ground-
water/surface water exchange. A variety of measurement methods are provided for each
parameter, and performance standards are provided when available, as shown in Table
7.1. Appendix Ac includes a list of all the Hydraulic measurement methods along with
information about the method's type, level of effort, level of complexity, and whether it is
a direct or indirect measure of the function-based parameter. The criteria used to make
these determinations are provided in Chapter 4.
Three different methods are provided for measuring floodplain connectivity and
respective performance standards. Performance standards are not provided for shear
stress and stream power; however, these are important measures of flow dynamics that
are used in the sediment transport competency and capacity discussion in Geomorphol-
ogy (Level 3). Performance standards are also not provided for groundwater/surface water
exchange. This parameter and methods for measuring it are included because of its
importance to Physicochemical (Level 4) functions and Biology (Level 5) functions. A
discussion is provided under Design Standards that illustrates how this parameter can be
used in a stream restoration design. Ultimately, as more reference research and project
surveys are completed, a better understanding of this parameter will emerge that may
allow for development of performance standards.
7.1 » PARAMETER: FLOODPLAIN CONNECTIVITY
Description
Floodplain connectivity describes how often streamflows access the adjacent flood-
plain. Fischenich (2006) included floodplain connectivity as part of the hydrodynamic
character function, which was considered the most important of the 15 functions ad-
dressed. In high-functioning alluvial valleys, all flows greater than the bankfull discharge
spread across a wide floodplain. In humid environments, streams that are well connected
to the floodplain also have relatively high water tables, encouraging the development of
riparian wetlands. In these systems, the channel is just deep enough to maintain sedi-
ment transport equilibrium and to create diverse bed forms and habitats.
Channelization is the primary impact that has directly disconnected streams from
A Function-Based Framework » May 2012
95
-------
Chapter 7: Hydraulics, Floodplain Connectivity
their adjacent floodplain. Schoof (1980) defines channelization as the widening, deepen-
ing and straightening of channels to increase their capacity for transporting flood flows
and to decrease flooding on adjacent land. Schoof (1980) estimates that over 200,000
miles of stream channels in the US have been modified over the past 150 years. He also
estimates that the primary effects of channelization have included draining of wetlands;
reduction in stream length through straightening; clearing of floodplain hardwoods;
lowering of groundwater levels; reduction of groundwater recharge from stream flow;
increase in erosion and sedimentation; and increase of downstream flooding. In a more
recent study, Kroes and Hupp (2010) evaluated the effect of channelization on floodplain
deposition and subsidence in a Maryland watershed. They found that the sediment
storage function of the river had been dramatically altered by channelization. Finally,
channelization has been found to reduce the size, number and species diversity in
streams (Schoof, 1980). Indirect impacts, like urbanization and increases to impervious
cover, also contribute to channel enlargement and incision through increased runoff. The
extra runoff often causes an increase in stream power, which leads to headcuts and
incision. The combination of increased runoff and channelization can lead to rapid
destabilization and adjustment of stream channels.
TABLE 7.1 HYDRAULIC PARAMETERS, MEASUREMENT METHODS AND AVAILABILITY OF
PERFORMANCE STANDARDS
PARAMETER
Floodplain Connectivity
Flow Dynamics
Groundwater/Surface Water
Exchange
MEASUREMENT METHOD
1. Bank Height Ratio
2. Entrenchment Ratio
3. Stage Versus Discharge
1. Stream Velocity
2. Shear Stress
3. Stream Power
1. Piezometers
2. Tracers
3. Seepage Meters
PERFORMANCE
STANDARD
Yes
Yes
Yes
Yes
No
No
No
No
No
Therefore, reconnecting streams to the floodplain is a major goal when working in
watersheds that have channelized/incised streams. Floodplain connectivity is a driving
force for many of the geomorphic and ecologic functions (Wohl, 2004; Shields et al.,
2010). It is also a parameter that can easily be assessed, modified as part of a design and
evaluated through monitoring, making it an excellent parameter for including a perfor-
mance standard.
Floodplain Connectivity by Stream Type
Floodplains are associated with streams in alluvial valleys. Alluvial valleys are typi-
A Function-Based Framework » May 2012
96
-------
Chapter 7: Hydraulics, Floodplain Connectivity
cally many times wider than the stream channel with longitudinal valley slopes less than
2%. Floodplain material is mostly comprised of alluvium (sand, silt and clay) that is
deposited from frequent overbank flooding and long-term channel migration (Bridge,
2003). Rosgen C, E and DA stream types are common in these alluvial valleys, with the
C and E stream types common as natural
channel design targets. The DA stream type
is associated with wetland/swamp systems
in coastal plain settings where flows are often
braided and diffuse. Restoring DA stream
types in coastal plain settings has become a
more common restoration approach in recent
years (USAGE Wilmington District and
NCDENR, 2005).
Colluvial valleys do not have wide, well-
developed floodplains and are naturally
confined between hillslopes. Colluvial valleys
have bowl-shaped cross sections and typi-
cally have valley slopes greater than 2%.
Colluvium is angular and poorly sorted
material that eroded from adjacent hill slopes
and then deposited on the valley floor or even
the channel (Easterbrook, 1999; Leopold et
al., 1992). The Rosgen B stream type is often
found in colluvial valleys. However, colluvial/
confined valleys do exist with valley slopes
that are less than 2%. The Rosgen Be stream
type is found in these low-gradient, but
confined valleys. Floodplain connectivity, therefore, is limited to a bankfull bench or
flood-prone area because the true definition of a floodplain is not relevant for these
settings. These features are much narrower than a fully developed floodplain; however,
they do dissipate flood energy and provide a flat depositional feature, which allows
riparian vegetation to become established.
Rosgen stream types A, G and F do not have floodplains. The A stream type is associated
with v-shaped valleys, which typically have longitudinal slopes greater than 4%. They
are rarely associated with stream restoration projects; however, they are often impacted
by surface mining activities in the Appalachian Mountains. The A stream types do not
have a floodplain, but can have small bankfull benches like the B stream type (Rosgen,
1996). When the drainage area for these stream types becomes very small and the chan-
nel is ephemeral, there may not be a bankfull discharge that represents channel formation.
The F and G stream types can exist in natural, stable environments like gorges. How-
ever, they are most often associated with unstable environments due to channelization
and urbanization (Rosgen, 1996). These stream types are very common targets for
Therefore, reconnecting
streams to the floodplain is a
major goal when working in
watersheds that have
channelized/incised streams.
Floodplain connectivity is a
driving force for many of the
geomorphic and ecologic
functions (Wohl, 2004;
Shields et al., 2010). It is also
a parameter that can easily
be assessed, modified as part
of a design and evaluated
through monitoring,
making it an excellent
parameter for including
a performance standard.
A Function-Based Framework » May 2012
97
-------
Chapter 7: Hydraulics, Floodplain Connectivity
stream restoration because they are disconnected from the floodplain and have often
evolved from C or E stream types through degradation and lateral erosion processes.
Therefore, the functional lift of reconnecting the stream to a floodplain is greatest in
these scenarios.
D stream types are associated with glacial outwash plains, alluvial fans and other
environments where sediment supply exceeds sediment transport capacity (Rosgen,
1996). D stream types in alluvial valleys are sometimes caused by land use changes and
can be restored to single-thread channels, often to a C stream type. This is more com-
mon in the arid West. However, in many other cases, D stream types are natural (glacial
outwash plains and alluvial fans) and should not be altered. Regardless, D stream types
are not incised and have access to a very active floodplain.
The descriptions above offer a general discussion of the three most common valley
types and their associated stream types. There are many subtle differences and changes
to valley morphology based on climate and geology, and a good description of the various
valley types can be found in Bridge (2003), Easterbrook (1999) and Rosgen (1996).
Measurement Method
There are simple to moderately complex methods for measuring floodplain connectiv-
ity. Simple methods include the bank height ratio and entrenchment ratio, both of which
require that the bankfull stage be determined. A more complex method is the use of
HEC-RAS, which can show the stage versus discharge relationship for a wide range of
return intervals, e.g., from base flow through the 100-year flood event. A brief description
of each method is given below.
1. Bank Height Ratio
The bank height ratio (BHR) is a direct measure of channel incision. This ratio is
calculated as follows:
BHR = Dtob /Dbf, where
Dtob = the depth from the top of the lowest bank to the thalweg
Dbf = the depth from the bankfull elevation to the thalweg.
A BHR of 1.0 means that all flows greater than bankfull are spreading onto a flood-
plain (C and E stream types) or bankfull bench/floodprone area (A and B stream types). A
BHR of 2.0 means that it takes a stage of two times the bankfull stage to access the
floodplain and the stream is highly incised. The bank height ratio can be measured from
a cross section or longitudinal profile if the profile includes the stream bed and both
banks (left and right) or the lowest profile of the two banks. Generally, it is preferable to
measure BHR from riffles along the profile because riffles represent the natural grade
control feature for a river. In this application, the BHR is not measured in the pool. An
example of measuring the BHR from a longitudinal profile and cross section is shown in
Figures 7.1 and 7.2, respectively.
A Function-Based Framework » May 2012 98
-------
Chapter 7: Hydraulics, Floodplain Connectivity
FIGURE 7.1 MEASUREMENT OF BANK HEIGHT RATIO FROM A LONGITUDINAL PROFILE
968
Low bank height = 3.5 ft
Bankfull max depth = 2.0ft
BHR= 3.5/2.0 = 1.8
Low bank height = 3.0 ft
Bankfull max depth = 2.0ft
BHR= 3.0/2.0 = 1.5
Thalweg
Left Top of Bank
Right Top of Bank
Water Surface
Bankfull
948
1200
1300
1400
1500
1600 1700
Station (ft)
1800
1900
2000
2100
Source: Reproduced with permission from Michael Baker Corporation
It should be noted that the BHR can be measured differently for other purposes. For
example, the Bank Erosion Hazard Index, developed by Rosgen (2001), calculates the
BHR by measuring the depth near the study bank, rather than the thalweg, and may
include measurements from a pool feature.
Measuring the bank height ratio from a profile or cross section is considered a moder-
ate level of effort and moderate level of complexity (see Appendix Ac) because of the time
and skill required to make the survey measurements. A rapid and simpler approach is
available for assessing the bank height ratio, which is often preferred by regulatory
agencies or others who quickly want to determine if a stream (pre- or post-restoration) is
incised. A rapid approach is best used if a regional curve is available. If it is, the riffle
mean depth from the curve can be used as an estimate for the bankfull max depth. Next,
measurements are made along the stream reach from the top of the bank to the bottom
edge of the channel, along riffle sections. This measurement is typically made with a
pocket rod or standard survey rod. The measurement can quickly be divided by the
bankfull depth to get the bank height ratio. If a regional curve is not available, at least one
measurement from a bankfull indicator is required, measuring from the indicator to the
edge of the water surface.
A Function-Based Framework » May 2012
99
-------
Chapter 7: Hydraulics, Floodplain Connectivity
FIGURE 7.2 MEASUREMENT OF BANK HEIGHT RATIO FROM A CROSS SECTION
970
968
966
e 964
c
o
UJ
• Low bank height = 6.6 ft
Max Bankfull depth = 3.9ft
BHR = 6.6/3.9 = 1.7
950
100
120
140
160 180
Station (ft)
200
220
240
Source: Reproduced with permission from Michael Baker Corporation
2. Entrenchment Ratio
The entrenchment ratio (ER) is a measure of the floodprone area width in relation to
the bankfull width (Rosgen 1994). The floodprone area width is measured at a stage of 2
times the bankfull max depth. Therefore, it is possible to have a stream that is incised,
e.g., BHR of 1.8, but not entrenched if the floodplain is wide. The ER is calculated in a
riffle cross section as follows:
ER=FW/BW, where
FW = floodprone width, measured at a stage of 2 times the bankfull max depth
BW = bankfull riffle width.
The BHR and ER work well together to quantify floodplain connectivity. For all
stream types, a BHR of 1.0 indicates that the stream is not incised and has access to a
floodplain or floodprone area. However, the ER will naturally vary by stream type.
Streams in v-shaped valleys (A stream types) and colluvial valleys (B stream types) will
have lower entrenchment ratios than streams in alluvial valleys (C, E and DA stream
types). Therefore a C or E stream type with a bank height ratio of 1.0 and an entrench-
ment ratio of 10 is not incised and has a wide floodplain that will minimize flood depths,
thereby encouraging flood storage, floodplain accretion and other floodplain processes. C
or E stream types that have a BHR of 1.0 and an ER of 2.5 are also not incised, but are
A Function-Based Framework » May 2012
100
-------
Chapter 7: Hydraulics, Floodplain Connectivity
more entrenched than the previous example, meaning that flood flows do not have as
large a floodplain to dissipate energy and provide wetlands.
FIGURE 7.3 MEASUREMENT OF ENTRENCHMENT RATIO
Entrenchment Ratio (ER)
ER = Floodprone Width / Bankfull Width
Two Times the
Bankfull Depth
Floodprone Width (FW)
Bankfull Width (BW)
3. Stage Versus Discharge
HEC-RAS (Hydrologic Engineering Center, River Analysis System) is a one-dimen-
sional stream flow model developed by the USAGE and is the most common analytical
tool for completing hydraulic analysis associated with stream assessment and restoration
projects. Regarding floodplain connectivity, HEC-RAS can be used to predict the stage of
various flood return intervals, e.g., bankfull, 2-year, 10-year, etc. A separate analysis of
Hydrology is used to determine the discharge for bankfull and the various return interval
floods (See Hydrology Chapter). Therefore, HEC-RAS can be used to show if the channel
carries the bankfull discharge, the 100-year discharge, or something in between. Obvi-
ously, if the channel carries the 100-year discharge, it is very incised; if it carries the
bankfull discharge, it is not incised. An example of using HEC-RAS to determine how
much water the channel will carry is shown in Figure 7.4. In this example, the channel
will carry the 5-year discharge. The bankfull discharge is shown as a dashed line and is
between the 1.1- and 1.5-year discharge. The bankfull stage came from the Geomorphic
assessment and was entered into HEC-RAS.
Dunne and Leopold (1978) created a dimensionless rating curve for gauge stations in
the Eastern US by plotting the measured flood depth divided by the bankfull depth (d/
dbkf), versus the measured flood discharge divided by the bankfull discharge (Q/Qbkf).
This relationship is shown below in Figure 7.5 and includes data from streams with
alluvial valleys. Relationships like this can be used to determine if stream restoration
projects have channels that are connected to an active floodplain. It does, however,
require an estimate of the bankfull discharge and knowledge that the curve represents
the hydro-physiographic region of the project. If the bankfull discharge is unknown, then
a return interval discharge of 1.5 can be used (as an estimate only) in the denominator.
Rosgen (1996) created similar curves by stream type. The G stream type is shown on
Figure 7.5 representing streams that are not connected to a floodplain. In the absence of
A Function-Based Framework » May 2012
101
-------
Chapter 7: Hydraulics, Floodplain Connectivity
bank height ratios and entrenchment ratios, these two curves can be used to assess
floodplain connectivity. Performance standards related to the use of these curves is
provided in the section below.
Performance Standard
Performance standards for floodplain connectivity metrics are shown in Table 7.2. The
BHR performance standards are adapted from Rosgen (2006), which include a graph
showing the relationship between BHR and a qualitative stream stability rating using the
following categories: stable, slightly incised, moderately incised and deeply incised.
These values relate to channel stability; however, to assess floodplain connectivity the
values were recategorized as Functioning, Functioning-at-Risk or Not Functioning.
FIGURE 7.4 HYDRAULIC ANALYSIS BYTHE HEC-RAS STREAM FLOW MODEL
OVERBAND RETURN INTERVAL 5-10 YEARS
1000
999
998
997-
996
995 ~l I I I I I I I I I I I I I I I I I I I I I I I I I I T
100 110 120 130 140 150
STATION (FEET)
Source: Adapted from original graph by Michael Baker Corporation
A Function-Based Framework » May 2012
102
-------
Chapter 7: Hydraulics, Floodplain Connectivity
FIGURE 7.5 DIMENSIONLESS RATING CURVE FOR GAUGE STATIONS IN THE EASTERN
UNITED STATES
0.1
Q/Qbkf
Souce: Adapted from Dunne and Leopold (1978), Leopold (1994), and Rosgen (1996)
TABLE 7.2 FLOODPLAIN CONNECTIVITY PERFORMANCE STANDARDS
MEASUREMENT METHOD
FUNCTIONING FUNCTIONING-
NOT FUNCTIONING
Bank Height Ratio (BHR)
Entrenchment Ratio (ER) for
C and E Stream Types
Entrenchment Ratio (ER) for
B and Be Stream Types
Dimensionless rating curve*
1.0 to 1.2
>2.2
> 1.4
Project site Q/
Qbkf plots on
the curve
AT-RISK
1.3 to 1.5
2.0to2.2
1.2 to 1.4
Project site Q/Qbkf
plots above the
curve
> 1.5
<2.0
< 1.2
Project site Q/Qbkf
of 2.0 plots above
1.6ford/dbkf
* See Figure 7-$ for dimensionless rating curve from Dunne and Leopold (1978).
The entrenchment ratio performance standards are also based on Rosgen (2006). The
Functioning category represents the minimum value for that stream type, e.g., a 2.2 for C
and E stream types. The Functioning-at-Risk category represents the amount that the
A Function-Based Framework » May 2012
103
-------
Chapter 7: Hydraulics, Floodplain Connectivity
ratio can vary and remain in the same stream type. For example, a C and E stream can
have an entrenchment ratio of 2.0 and still be a C or E stream type based on what Rosgen
calls the "continuum of physical variables". However, a decreasing entrenchment ratio is a
negative trend because it indicates that the valley is becoming more confined and flood-
plain processes are diminishing.
Between the BHR and ER, the BHR is the most important for achieving functional lift
because it is a direct measure of incision and, therefore, floodplain connectivity. It does
not, however, provide information about how far water can spread onto the floodplain.
The ER is a nice complement to the BHR because it accounts for the width of the flood-
plain/valley once floodwaters leave the channel. The ER becomes more critical for resto-
ration projects that include floodplain excavation. It would be extremely rare for this type
of project to have an ER of 10, for example. Instead, minimum ER values will be used to
lower construction cost and meet landowner constraints. These minimums should not
exceed the values listed in 7.2. In addition, an excavated floodplain should be relatively
straight with the fall line of the valley and should not simply follow the pattern of the
channel using a constant floodplain width to achieve the targeted ER. An example is
shown below in Figure 7.6.
It is more difficult to use discharge as a performance standard because the discharge
rating curve varies by the shape of the channel (Leopold, 1994) and the degree of incision.
However, rating curves from different gauge stations become quite similar when the
values are converted to a dimensionless form (Leopold, 1994). If the d/dbkf versus Q/Qbkf
plots on the curve, then the stream is connected to the floodplain. If data from the project
site plot above the curve, it means that stage is increasing at a higher rate than the non-
incised streams used to create the curve. This is likely caused by a deeper channel, and
the additional discharge is not spreading onto an active floodplain as quickly. If the
project site plots near the curve, it may still be functioning similar to reference reach
streams, but it is Functioning-at-Risk. As the project site plots further from the curve, the
risk of channel incision increases.
Rosgen (1996) shows a dimensionless discharge rating curve stratified by stream type.
This relationship shows that the G stream type at a Q/Qbkf of 2.0 has a d/dbkf of 1.6.
The breakpoint for Not Functioning floodplain connectivity was therefore set at a d/dbkf
of 1.6 for a Q ratio of 2.0, indicating a potential stream type change of a C or E to a G.
Again, it would be easier to use the BHR and ER (and then stream type) to make this
determination. However, a practitioner or reviewer could use gauge station data or pub-
lished dimensionless discharge rating curves and the 1.5-year Q for bankfull to make an
estimate of floodplain connectivity performance.
A Function-Based Framework » May 2012 104
-------
Chapter 7: Hydraulics, Flow Dynamics
FIGURE 7.6 PROPER VERSUS IMPROPER FLOODPLAIN EXCAVATION DESIGN
GOOD EXAMPLE
EDGE OF FLOODPLAIN
EDGE OF FLOODPLAIN
BAD EXAMPLE
7.2 » PARAMETER: FLOW DYNAMICS
Description
The water flowing in a stream channel moves downhill because of gravity and slope.
The flow is then retarded by resistance applied by the stream bed and banks. The interac-
tion of flowing water against the stream bed and banks creates dynamic flow conditions,
termed here as flow dynamics. The morphology of natural channels is dependent on
these flow dynamics. In intermittent and perennial streams, the discharge of groundwa-
ter and the overall surface/subsurface interaction creates additional functions, especially
as they relate to and support Physicochemical and Biology functions.
There are many resources that describe flow dynamics in stream channels and flood-
plains. A few include Knighton (1998), Leopold et al. (1992), Fetter (1994) and Bridge
A Function-Based Framework » May 2012
105
-------
Chapter 7: Hydraulics, Flow Dynamics
(2003). Flow dynamics have a major role in shaping the geometry of the channel. There-
fore, restoration practitioners spend a considerable amount of time determining the
proper flow dynamics for a restoration project. Assessing flow dynamics for establishing
a baseline functional capacity or determining functional lift could include a wide range of
measurements, ranging from surface/subsurface interactions, stage versus discharge
relationships, velocity distributions, shear stress or tractive force, and stream power.
Many of these metrics relate to the ability of the stream to "do work" by transporting
sediment that is delivered to the channel from upstream sources, the stream bed, and
streambanks. Sediment transport parameters (sediment transport capacity and compe-
tency) are discussed in the Geomorphology Chapter because they describe the Geomor-
phology function of transporting sediment.
Three important measures of flow dynamics are described here: stream velocity, shear
stress and stream power. However, they are also applied in the Geomorphology Chapter
for assessing channel stability and sediment transport. These Hydraulic parameters
influence channel stability and sediment transport by providing the force and power
needed for Geomorphic functions to occur, e.g., transport of organic material and sedi-
ment to create diverse bed forms and dynamic equilibrium.
Measurement Method
1. Stream Velocity
Stream velocity is a vector that has magnitude and direction. Knighton (1998) de-
scribes stream velocity as one of the most sensitive and variable properties of open-chan-
nel flow because it is dependent on a wide range of factors. Knighton (1998) describes the
variability in four different ways, including distance from the stream bed, across the
stream channel and downstream, as well as with time. It is the character of this variation
that is important because of its influence on erosion, sediment transport and deposition.
Stream velocity is also important at baseflow and flood flow conditions. Baseflow veloci-
ties that are too high prevent upstream fish movement, and high stream velocities during
flood flows can cause stream bed and bank erosion if the flow force exceeds the resisting
forces. Therefore, stream velocity is a widely used parameter to help assess channel
stability, create stable channel designs and help support aquatic life.
The bankfull discharge and other flow magnitudes, e.g., the 100-year discharge, are
determined as part of the Hydrology assessment discussed in Chapter 6. The average
bankfull velocity is calculated as the bankfull discharge divided by the cross-sectional
area, which can be measured during an assessment of the pre- or post-restoration condi-
tion. In other words, the bankfull discharge is a design element and will not change after
restoration construction, but the cross-sectional area may change after construction, and
this change can be positive or negative. Dunne and Leopold (1978) noted that the average
bankfull velocity is approximately 4 feet/sec. Published regional curves, however, show
bankfull velocities varying by stream type.
Velocity can also be measured in the field; this is easier to do during baseflow conditions
than bankfull or flood conditions. Velocity may be measured in the field to assure that
A Function-Based Framework » May 2012 106
-------
Chapter 7: Hydraulics, Flow Dynamics
baseflbw velocities will allow for fish passage and to measure discharge (discharge = velocity
x the cross-sectional area). This may be important for stream restoration projects that
include culvert removal or other barriers to fish passage. Dingman (2008) and Harrelson
et al. (1994) provide detailed methods on a variety of ways to measure stream velocity and
discharge. A single velocity measurement as described above is considered a rapid level of
effort with moderate complexity. However, taking velocity measurements for a range of
flow conditions to develop a stage versus discharge rating curve requires multiple trips
and more expertise and is considered an intensive level of effort and complex (Appendix Ac).
2. Shear Stress
Shear stress is a hydraulic force that is often used to predict sediment entrainment
(sediment transport competency). Regarding the Pyramid, shear stress is a Hydraulic
parameter (Level 2) that is used to quantify a Geomorphology function (Level 3), the
entrainment and transport of bed material. Most stream beds consist of unconsolidated,
cohesionless grains of sand and gravel. As flow increases, the force of the water over
these particles increases. At some threshold, the particles begin to move. This initial
movement is commonly defined as the critical shear stress (Tcr) or mean boundary shear
stress (TO) (Knighton, 1998). The mean boundary shear stress is calculated as:
TO = yRs, where
TO = mean boundary shear stress in lbs/ft2
y = the specific weight of water (typically 62.4 lbs/ft3)
R = hydraulic radius in ft
S = average channel slope in ft/ft.
There are many ways to calculate critical shear stress, and it is beyond the scope of
this document to review them all here. However, Knighton (1998) and Wilcock et al.
(2009) provides a description of the different ways to calculate critical shear stress,
including a variety of graphs and equations that can be used to predict erosion, transport
and deposition. Moreover, Rosgen (2006) provides an application of Andrews (1983 and
1984) equations for estimating the depth needed to maintain bed equilibrium during a
bankfull event, and Wohl (2000) provides a description of entrainment processes in
mountain rivers. Rosgen (2006) also created a relationship between particles transported
at near bankfull flows versus the boundary shear stress. These procedures are described
in more detail in the Geomorphology Chapter. Simple calculations of shear stress and its
use with existing graphs is considered a moderate level of effort and moderate complexity
because sufficient expertise is required to know when to use this method over other
methods. The level of effort and complexity becomes intensive if shear stress curves are
developed for a certain region, which requires bedload/material samples for a range of
flow conditions (Appendix Ac).
3. Stream Power
Stream power is the ability of the stream to do work, where work is defined as the
A Function-Based Framework » May 2012 107
-------
Chapter 7: Hydraulics, Flow Dynamics
conversion of potential energy (elevation change) to kinetic energy. Most of the kinetic
energy is dissipated through friction from the bed and banks. However, a small portion is
available to accomplish geomorphic work like the entrainment and transport of sediment
(Bagnold, 1960). Phillips (1989) provides a cross-sectional stream power calculation,
which is a physically based measure of sediment transport capacity. Thus, cross-sectional
stream power can be written as:
Q = yQS, where
Q= stream power per unit length (Watts/meter)
Y = specific weight of water (1 g/m3)
Q = discharge (m3/s)
S = slope (m/m).
Mean stream power is related to competence and can be expressed as:
ro = yRSV = Q/W = xV (Lecce, 1997)
co = unit or mean stream power (W/m2)
R = hydraulic radius (m)
V = velocity (m/s)
W = width (m).
As a functional assessment tool for stream restoration projects, mean stream power is
more useful than cross-sectional stream power. This is because mean stream power is
normalized by channel width and can be compared across various streams of different
size. Mean stream power is also the product of shear stress and velocity, which were each
discussed above. In this regard, mean stream power is probably the most important
parameter for describing flow dynamics. It is also a vital input parameter for sediment
transport functions, as described in the Geomorphology Chapter. Similar to shear stress,
if stream power is calculated and compared to literature values or existing graphs, the
level of effort and complexity is moderate. However, if stream power curves (sediment
transport rate versus stream power) are developed the level of effort and complexity is
complex (Appendix Ac).
Nanson and Croke (1992) used stream power to classify floodplains into three classes:
High-energy non-cohesive floodplains with bankfull co greater than 300 W/m2; medium-
energy non-cohesive floodplains with bankfull co between 10 and 300 W/m2; and low-
energy cohesive floodplains with bankfull co below 10 W/m2. To further divide the
classes into orders and suborders, nine discriminatory fluvial geomorphic factors are
added. These factors include: (1) Valley Confinement, (2) Channel Cutting and Filling, (3)
Braid-channel Accretion, (4) Lateral Point Bar Accretion, (5) Overbank Vertical-accretion,
(6) Annabranching, (7) Scroll-bar Formation, (8) Counterpoint Accretion and (9) Organic
Accumulation. The first six factors are used to divide the classes into orders, and the
remaining three are used to divide the floodplains into suborders.
This is one example of how stream power can be used to assess the functional capacity
of a potential steam restoration site. For example, there are many low energy floodplains
A Function-Based Framework » May 2012 108
-------
Chapter 7: Hydraulics, Flow Dynamics
(oo less than 10 W/m2) in the Piedmont and Coastal Plain regions of the eastern United
States. But these floodplains lack many of the processes (factors) described above due to
channelization, floodplain aggradation, deforestation and other direct and indirect distur-
bances. The Nanson and Croke (1992) floodplain classification provides restoration practitio-
ners with a framework of processes that can be incorporated into restoration goals and then
quantified during design and monitoring as functional lift. It also provides guidance to
help ensure that the right type of stream channel is designed given the valley morphology.
Performance Standard
The measurement methods used to describe flow dynamics include stream velocity,
shear stress and stream power. Shear stress and stream power are important input param-
eters for assessing sediment transport; however, there are other Geomorphology param-
eters and measurement methods that are better for developing performance standards.
Stream velocity can be used as a flow dynamics performance standard, especially for
evaluating the appropriate bankfull discharge (and flow area) and for fish passage. Bank-
full velocity performance standards should be based on local regional curves stratified by
stream type and the bankfull cross-sectional area measured in the field. Example perfor-
mance standards by stream type are provided below in Table 7.3.
TABLE 7.3 FLOW DYNAMICS PERFORMANCE STANDARDS
MEASUREMENT METHOD
Bankfull Velocity for C and E
stream types (ft/s)
Bankfull Velocity for Cc-
(ft/s)
Bankfull Velocity for B
stream types (ft/s)
FUNCTIONING
3 to 6
<3
4 to 6
FUNCTIONING-
AT-RISK
6 to 7
3 to 4
6 to 7
NOT FUNCTIONING
>7
>5
>7
Bankfull velocities typically should not exceed the range of velocities provided by
gauge sites used to develop regional curves. For C and E stream types with slopes be-
tween 0.005 and 0.02 ft/ft, the average bankfull velocity is 4 ft/s (Dunne and Leopold,
1978). However, these values only provide general guidance and are not the best perfor-
mance standard for stream restoration projects. Values outside of the range shown can
indicate a potential problem (usually with stability), but the bank height ratio parameter
and other parameters in the Geomorphology Chapter are probably better suited for
stream restoration performance standards.
A wide range of velocity performance standards may be applied to projects with fish
passage issues and should be based on the fish species and site conditions, e.g., open channel
or culvert crossing. Stream assessments and restoration projects often deal with culvert
crossings and associated fish passage issues. The FishXing (pronounced "fish crossing")
A Function-Based Framework » May 2012
109
-------
Chapter 7: Hydraulics, Groundwater and Surface Water Exchange
software is a free tool that can be used to design culvert crossings for passage. The FishX-
ing website includes references and supporting materials that could be used for assessing
velocity thresholds for a variety of fish species (www.stream.fs.fed.us/fishxing/index.html}.
7.3 » PARAMETER: GROUNDWATER AND SURFACE WATER EXCHANGE
Description
Surface water in streams interacts with groundwater in three basic ways: groundwater
discharging into the stream through the stream bed (gaining stream), surface water
flowing through the bed and into groundwater (losing stream), or a combination of both
(Winter et al., 1998). This document describes the processes of groundwater and surface
water exchange as it relates to stream assessments and restoration. An overview of
groundwater hydrology is not provided; however, Fetter (1994) and Winter et al. (1998)
are good sources for background information.
Figure 7.7 shows examples of a gaining and losing stream. Gaining streams are charac-
terized as zones where the water table is higher than the stream bed. Losing streams are
the opposite — areas where the water table is below the elevation of the stream bed.
Losing streams can be connected to the water table by a continuous zone of saturation or
by an unsaturated zone (Fetter, 1994; Winter et al., 1998).
In some environments, stream reaches are almost always gaining or losing. However,
in other environments, surface and groundwater exchange is more variable, e.g., headwa-
ter streams. Flow direction toward or away from the stream bed can change quickly,
based on flood events that cause recharge near the streambank, short-term flood peaks or
transpiration of groundwater by riparian vegetation. A very common type of groundwa-
ter and surface water interaction during storms is called bank storage, which occurs
during a rapid rise in stream stage (depth). As the stage increases, water flows from the
channel into the unsaturated portion of the streambank. If the storm does not overtop
the streambank and spread onto the floodplain, water stored in the banks (bank storage)
typically returns to the channel within a few days or weeks. If the storm does overtop
the bank and spread onto the adjacent floodplain, widespread recharge to the water table
occurs as water seeps through the unsaturated zone (Winter et al., 1998). The timeframe
for this water to return to the channel through groundwater flow may take weeks, months
or even years. Depending on the frequency, magnitude and intensity of storms in a given
region, the stream and adjacent aquifer may be continuously readjusted based on these
processes (Winter et al., 1998). This is another reason that floodplain connectivity is so
important. Streams that overtop the streambank frequently (all flows greater than bank-
full) have more opportunity to store and slowly return flood flows to the channel. Figure
7.8 illustrates these two processes (bank storage and recharge) as stream stage increases.
The processes described above occur during storm events; however, many gaining
streams have reaches that lose water to the aquifer during baseflow conditions. The direc-
tion and rate of seepage through the bed is often related to abrupt changes in bed slope
and meander bends. This subsurface zone where stream water flows through short
segments of the bed and banks is called the hyporheic zone. The hyporheic zone is a
A Function-Based Framework » May 2012 110
-------
Chapter 7: Hydraulics, Groundwater and Surface Water Exchange
FIGURE 7.7 GAINING AND LOSING STREAM EXAMPLES
(In the illustration, A shows gaining stream and B shows a losing stream with an unsaturated zone.)
Source: Adapted from Winter a al. (1998)
subsurface area of porous sediments where surface water and groundwater mix, thereby
creating an environment that is different from the stream or the groundwater (Figure 7.9).
This unique environment can have a large effect on the types and numbers of organ-
isms (Level 5 - Biology) found in the stream. The importance of the hyporheic zone is
increasingly being recognized in stream and watershed assessments. As such, restoration
approaches that help to encourage the development of a hyporheic zone are being identi-
fied and implemented. These restoration techniques include adding meanders, creating
bed form diversity (steep riffles and flat pools), adding gravel layers beneath the ground
surface of the floodplain and sometimes step structures like cross vanes. Since these design
elements must be included as part of a sediment transport analysis and overall stable
geometry, it is included in Pyramid Level 3 (Geomorphology) rather than Level 2 (Hydraulic).
A Function-Based Framework » May 2012
111
-------
Chapter 7: Hydraulics, Groundwater and Surface Water Exchange
FIGURE 7.8
(In the figure, A shows gaining stream, B shows bank storage and C shows groundwater recharge
associated with overbank flooding.)
LAND SURFACE
(flood plain)
STREAM BANK
STREAMBED
B
SEQUENTIAL STREAM STAGES
APPROXIMATE DIRECTION OF GROUND WATER FLOW
OR RECHARGE THROUGH THE UNSATURATED ZONE
Source: Adapted from Winter et al. ('1998)
A Function-Based Framework » May 2012
112
-------
Chapter 7: Hydraulics, Groundwater and Surface Water Exchange
FIGURE 7.9 HYPORHEIC ZONE
VIEW FROM ABOVE
FLOW
POOL
VIEW FROM THE SIDE
FLOW LINES
RIFFLE
LOG STEP
Source: Adapted from Waterencydofedia.com
Measurement Method
There are many ways to measure groundwater/surface water interactions; however,
mapping the extent of the hyporheic zone is challenging. Kalbus et al. (2006) provides a
thorough review of methods to measure groundwater discharge into streams, stream
recharge of groundwater and the interactions between the two. This document only
highlights three methods described by Kalbus et al. (2006), piezometers, tracers and
seepage meters, because they are the most likely methods to be used by stream profes-
sionals. However, refer to Kalbus et al. (2006) for a more thorough review of methods.
1. Piezometers
A piezometer is a small diameter well with a short screen or section of slotted pipe at
the bottom end. It is used to measure hydraulic head (Fetter, 1994) and can usually be
installed by hand. As such, it is probably the most common method for measuring the
hyporheic zone. Piezometers are typically installed in the stream bed. This type of
installation shows if the stream is gaining or losing by comparing the water elevation in
the piezometer to the adjacent water elevation of the stream. If the water elevation in the
piezometer is lower than the adjacent stream elevation, the stream is losing water to the
hyporheic zone and vice versa. Transects of piezometers are installed throughout the
stream reach to delineate gaining and losing areas. Additionally, water samples can be
collected and the chemistry compared between the stream and the piezometer. This can
be compared to results from piezometers installed in the floodplain to delineate the
A Function-Based Framework » May 2012
113
-------
Chapter 7: Hydraulics, Groundwater and Surface Water Exchange
lateral extent of the hyporheic zone, thus providing the depth and lateral extent.
2. Tracers
Tracers, or dye, can also be used to measure flow velocity in the hyporheic zone. A
known concentration of the tracer is injected into the sediments below the stream bed.
Water samples are then collected downstream to determine the concentration of the dye.
Tracer studies are often used in combination with computer models to estimate the flow
dynamics in the stream channel and hyporheic zone.
3. Seepage Meters
Bag-type or automatic seepage meters are also used to measure groundwater/surface
water interaction. There have been problems with using the bag-type meter in stream
systems, many of which have been overcome by the automatic seepage meter. The
automatic meter records velocities using a heat pulse, an ultrasonic device or an electro-
magnetic flow meter.
Design Standard
The development of a hyporheic zone is critically important to support Physicochemi-
cal and Biological processes. There are stream restoration techniques that can be used to
support the development of a hyporheic zone. Some examples include adding meanders,
creating step-pools or steep gradient riffles, adding bed form complexity, and creating
porous subsurface sediments. As stream restoration technologies advance, there is an
increase in working with bed sediments, and even loosening sediments that have been
previously compacted in the floodplain. However, developing performance standards for
groundwater/surface water exchange is difficult. The science is emerging, but currently
there are no quantitative standards to say that a hyporheic zone is Functioning, Function-
ing-at-Risk or Not Functioning. The best opportunity for developing a performance
standard would be cases where a reference reach is upstream or downstream of the
project. In this case, the design goal could be to have a hyporheic zone that is similar in
depth and width to the reference reach, which could be assessed using piezometers.
Another option is to use Level 5 parameters like macroinvertebrate communities, since
many of these organisms rely on the hyporheic zone as a critical habitat.
A Function-Based Framework » May 2012 114
-------
Chapter 8
Geomorphology
Level 3 on the Pyramid represents the Geomorphology functions, which transport and
store organic matter (wood) and sediment to create diverse bed forms and dynamic
equilibrium. These functions include the interaction of flowing water with the stream
bed, streambanks and upstream sediment supply. Therefore, the assessment and restora-
tion of Geomorphology functions come after an assessment of the Hydrology (Level 1)
and Hydraulic (Level 2) functions, as the Geomorphology functions integrate both of
these preceding functions.
The interaction between flowing water and sediment transport creates bed forms like
riffles, runs, pools and glides, which provide the critical habitats for macroinvertebrates,
fish and other organisms. Streams that are in balance with Hydraulic and Geomorphol-
ogy functions are said to be in dynamic equilibrium. This means that the stream bed is not
aggrading nor degrading over time, and that lateral adjustments do not change the cross-
sectional area, even though its position on the landscape may change (Hack, 1960).
Table 8.1 provides a list of the parameters included in Level 3, along with methods for
measuring the parameters. An indication of whether or not a measurement method
includes a performance standard is also provided. A description of each parameter,
measurement method and performance standards are provided below. Appendix Ac
includes a list of all the Geomorphology measurement methods along with information
about the method's type, level of effort, level of complexity, and whether it is a direct or
indirect measure of the function-based parameter. The criteria used to make these deter-
minations are provided in Chapter 4.
8.1 » PARAMETER: SEDIMENT TRANSPORT COMPETENCY
Description
The ability of the stream to transport its sediment load can be determined through
sediment transport competency and capacity analyses. Sediment transport competency is
the ability of a stream to move particles of a given size and is a measurement of force,
often expressed in units of pounds per square foot (lbs/ft2). A description of shear stress is
provided in the Hydraulics Chapter. Sediment transport competency is a common param-
eter used to determine the vertical stability of a gravel bed stream. Competency analysis
is typically not completed in sand bed channels because all particle sizes are mobile.
Sediment transport competency is used more during the stream restoration design
phase than for evaluating performance during the post-restoration monitoring phase.
Other parameters, such as bed form diversity, are easier to measure during the monitor-
A Function-Based Framework » May 2012
115
-------
Chapter 8: Geomorphology, Sediment Transport Competency
TABLE 8.1 GEOMORPHOLOGY PARAMETERS, MEASUREMENT METHODS AND AVAILABILITY
OF PERFORMANCE STANDARDS (CONT.)
PARAMETER
Channel Evolution
Bank Migration/Lateral
Stability
Riparian Vegetation
Bed Form Diversity
Bed Material
Characterization
Sediment Transport
Competency
Sediment Transport
Capacity
Large Woody Debris
Transport and Storage
MEASUREMENT METHOD
1. Simon Channel Evolution Model
2. Rosgen Stream Type Succession
Scenarios
1. Meander Width Ratio
2. BEHI/NBS
3. Bank Pins
4. Bank Profiles
5. Cross-Sectional Surveys
6. Bank Stability and Toe Erosion Model
1. Buffer Width
2. Buffer Density
3. Buffer Composition
4. Buffer Age
5. Buffer Growth
6. Canopy Density
7. Proper Functioning Condition (PFC)
PERFORMANCE
STANDARD
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
8. NRCS Stream Visual Assessment Yes
Protocol
9. Rapid Bioassessment Protocol
10. Watershed Assessment of River
Stability and Sediment Supply
(WARSSS)
11. USFWS Stream Assessment Ranking
Protocol (SAR)
1. Percent Riffle and Pool
2. Facet Slope
3. Pool-to-Pool Spacing
4. Depth Variability
1. Bevengerand King (1995)
2. Riffle Stability Index (RSI)
1. Shear Stress Curve
2. Required Depth and Slope
3. Spreadsheets and Computer Models
1. Computer Models
2. FLOWSED and POWERSED
3. BAGS
1. Wohletal. (2009)
2. Large Woody Debris Index
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
Yes
A Function-Based Framework » May 2012
116
-------
Chapter 8: Geomorphology, Sediment Transport Competency
ing phase to determine if sediment transport processes are working properly. For exam-
ple, if the stream is aggrading, excessive bar development, e.g., mid channel bars, will be
obvious. If the stream is degrading, headcuts and the lack of pool features will be obvious.
Therefore, the measurement methods described below are typically used to assess refer-
ence reach and project reach streams. Design standards are discussed after the measure-
ment methods; however, performance standards are not included for this parameter.
Measurement Methods
1. Shear Stress Curve
There are a variety of methods for assessing sediment transport competency in gravel
bed streams, most of which are based on tractive force or shear stress calculations. Ros-
gen (2006) measured bedload from Colorado Rivers and combined this data set with the
high outliers from a Leopold, Wolman and Miller (1964) data set. This form of boundary
shear stress is used by Rosgen (2006) to predict particle sizes that may be transported
during a bankfull event. It is therefore a rapid assessment tool that does not require detailed
modeling or intensive field work, only a cross section, average slope measurement and
grain size distribution of the bed material. The result is shown below in Figure 8.1.
FIGURE 8.1 GRAIN SIZE ENTRAINED AS A FUNCTION OF SHEAR STRESS
I 10
D
|
•
a.
c
;
Leopold Wdman A Miller 1964
Leopold WoUrun 1 Miller 1964 (upper outliers)
< Trendww (Colorado Date • Upper outliers Leopold
Wolmsn » Miller 1964)
-Tr en dime (Leopold Wolmsn I Miller 1984)
Colorado Data * upper outliers
Leopold. Wolman & Miller. 1964
Power TrencJine
Dia (tnm> = 253 7 -
K-- 09511
Leopold Wolman 4 Miller. 1964
Power TrenoJine
Dia (mm| = 77 966 -
R =09336
T - Critic* SwarSuss i IM/SqFI i
Source: US EPA Watershed Assessment of River Stability and Sediment Supply (WARSSS) vl.O
A Function-Based Framework » May 2012
117
-------
Chapter 8: Geomorphology, Sediment Transport Capacity
The upper line represents data measured in natural rivers at or near the bankfull
discharge, along with upper outliers from the Leopold, Wolman and Miller (1964) curve.
The upper curve is used more often to assess sediment transport competency in stream
restoration projects. However, it is an empirical tool and data from the project reach
should be representative of the data used to create the curve (Rosgen, 2009). If it is not,
then local curves should be developed in order to use the curve for design or assessment
purposes. The development of a local curve requires an intensive level of effort and
should only be developed by qualified scientists or engineers (Appendix Ac).
2. Required Depth and Slope
Rosgen (2006) also describes a much more detailed procedure that involves sampling
bed material from the riffle pavement (surface layer) and the riffle subpavement, or
material from the point bar. The material is sieved and a grain size distribution for the
pavement and subpavement or point bar is developed. A series of calculations are then
made using equations from Andrews (1984) and Andrews and Erman (1986) to determine
the depth and slope required to move the largest particle from the subpavement or bar.
From past monitoring, Rosgen has determined that the largest particle from the subpave-
ment or point bar closely matches the largest particle sampled during a bankfull event.
The required depth and slope can then be compared to the project reach depth and slope
(could be a pre- or post-restoration condition as well). If the required depth and slope is
greater than the project depth and slope, then there is a potential for stream bed aggrada-
tion because more shear stress is needed to move the bed. If the required depth and slope
is less than the project depth and slope, then there is risk of bed degradation because
there is more shear stress than is necessary to move the bed, e.g., all particle sizes may be
transported rather than the largest size from the sub-pavement or bar sample.
3. Spreadsheets and Computer Models
Several computer models can be used to assess vertical stability, including those
ranging from rapid/simple spreadsheet programs like BAGS to one-dimensional models
like HEC-RAS, as well as the more sophisticated two-dimensional models. These models
typically compute competency and capacity with more emphasis placed on capacity. A
description of these techniques is provided below.
Design Standard
Sediment transport competency and capacity are often assessed together. Therefore,
design standards for both parameters are discussed in the following section (Parameter:
Sediment Transport Capacity).
8.2 » PARAMETER: SEDIMENT TRANSPORT CAPACITY
Description
Sediment transport capacity is the ability of a stream to move a quantity of sediment
through a riffle cross section. It is typically assessed using stream power, and is often
A Function-Based Framework » May 2012 118
-------
Chapter 8: Geomorphology, Sediment Transport Capacity
expressed as units of watts/square meter (W/m2). A description of stream power is
provided in the Hydraulics Chapter. Sediment transport capacity is often shown as a
sediment transport rating curve, which provides an estimate of the quantity of total
sediment (load) transported through a cross section per unit time. The curve is provided
as a sediment transport rate versus discharge or stream power. An example of a sediment
transport rating curve is shown below in Figure 8.2.
FIGURE 8.2 A MODELED SEDIMENT RATING CURVE FOR A PROJECT IN NC
20.9
167
-------
Chapter 8: Geomorphology, Sediment Transport Capacity
significantly with time and, therefore, the sediment supply to the project reach will
change. This is one reason that it is preferable to select restoration reaches downstream of
stable reaches. Another complicating factor is that a restoration design may have a goal to
store sediment rather than have a transport reach. Furthermore, projects with a low
sediment supply may not need a quantitative sediment transport analysis. Innovative
design approaches like those shown on Figure 6.2 are redefining approaches for assessing
sediment transport.
1. Computer Models
There are several computer models that can be used to quantify sediment transport
capacity. HEC-RAS Version 4.1 has a sediment transport feature that can easily be run if a
hydraulic model has already been developed for the project and bed material data are
available. Another option is SAMWin, which is a single cross-section analyzer using a
variety of sediment transport capacity equations. The software then predicts a stable
cross-sectional geometry based on a Copeland stability curve and other methods (Thom-
as et al., 2002). More information about SAMWin, as well as a free download of the
software and supporting documents, can be found at chl.erdc.usace.army.mil/chl.
aspx?p=s&a=SOFTWARE;2.
Two-dimensional models are also becoming more prevalent for assessing channel
hydraulics and sediment transport capacity. Two examples of commercially available 2-D
models with hydraulic and sediment transport modeling capabilities are provided below.
RiverFLO -2D www. flo-2d. com/products
Mike 21 www.mikebydhi.com
2. FLOWSED and POWERSED
Rosgen (2006) developed an empirical approach to assessing sediment transport
capacity. This approach is used to develop dimensionless bedload and suspended rating
curves by normalizing the measured transport rates by the bankfull value. Dimensionless
rating curves are developed for the project reach and as a reference reach for comparison.
Sediment supply often increases in unstable streams, which will cause the curve to shift
toward finer sediment sizes. This shift can then be compared to the reference curve to
determine if the shift is significantly different.
This approach has been automated and further advanced through the FLOWSED and
POWERSED models (Rosgen, 2006). FLOWSED is a model that is used to estimate annual
sediment supply/loading, and it is often used to determine functional capacity by compar-
ing results of a project reach to a reference reach, or pre-restoration conditions to post-
restoration conditions. FLOWSED is also used to input sediment supply into POWERSED,
which is used in conjunction with FLOWSED to determine channel stability. POWERSED
includes a hydraulic analysis in order to calculate sediment transport capacity. FLOWSED
and POWERSED are included in the RIVERMorph software program (www.rivermorph.com).
A Function-Based Framework » May 2012 120
-------
Chapter 8: Geomorphology, Large Woody Debris Transport and Storage
3. Bedload Assessment in Gravel-bedded Streams (BAGS)
A simpler spreadsheet-based program called Bedload Assessment in Gravel-bedded
Streams (BAGS) was developed by Pitlick et al. (2009). BAGS predicts sediment transport
using six different bedload transport equations developed for gravel bed streams. A
sediment transport primer by Wilcock et al. (2009), a user manual, and the BAGS pro-
gram is available from www.stream.fs.fed.us/publications/bags.html. The primer is a good
document for those who want to learn more about the fundamentals of sediment trans-
port processes.
Design Standard
Sediment transport competency and capacity are two of the most important design
elements for stream restoration projects located in transport zones. Transport zones are
stream reaches that receive significant sediment supply from upstream and adjacent
sources. The project reach must be able to transport this load in order to maintain equilib-
rium. If a project is located in a reach where there is not significant sediment supply, like a
small headwater stream or perhaps an urban channel, sediment transport competency
and capacity analyses are less important.
In either case, sediment transport calculations are probably more useful as a design and
assessment parameter than for determining post-restoration performance. If sediment
transport calculations are wrong and the design is flawed as a result, stability problems
will be obvious without the need for recalculating competency and capacity (although
calculations may help to understand why a project is not properly transporting the
sediment load). Indicators of sediment transport problems include excessive bar development
(aggradation) and head-cutting (degradation), among others. Harman and Starr (2011)
provide a checklist that can be used to help assess whether a natural channel design
included the appropriate sediment transport analyses. The checklist is available for free
download at http://water.epa.gov/lawsregs/guidance/wetlands/wetlandsmitigationjndex.cfm
under Technical Resources for Mitigation or www.stream-mechanics.com.
In addition, Rosgen (2006) provides a comprehensive method for assessing vertical
stability using a wide range of quantitative and qualitative methods. Other parameters
from the Pyramid, like depth variability, percent riffle and pool, and lateral stability
provide better performance standards because they represent the result of proper sediment
transport. If the channel is in equilibrium, there is a greater probability that the appropri-
ate bed features will form and the streambanks will have low erosion rates (rates that are
comparable to reference reaches).
8.3 » PARAMETER: LARGE WOODY DEBRIS TRANSPORT AND STORAGE
Description
In addition to sediment, streams also transport, store and breakdown organic matter.
Of course the type of organic matter and the rates of transport, storage and breakdown or
decomposition vary greatly across the US, with the greatest rates being in forested head-
water streams. A forested riparian buffer delivers many types of organic matter to the
A Function-Based Framework » May 2012 121
-------
Chapter 8: Geomorphology, Large Woody Debris Transport and Storage
stream, including leaves, large woody debris (LWD), dissolved organic compounds, feces
and even dead animals (Richardson et al., 2005). LWD includes logs, limbs and whole
trees that are sometimes transported or stored in the channel and oftentimes stored on
the floodplain and floodprone area (Wohl, 2000).
The minimum size for organic matter to be classified as LWD is often reported as 10
cm in diameter (Wohl, 2000). Davis et al. (2001) defines LWD as having a 10-cm diameter
at one end and is over 1 m in length. There is no maximum size for LWD, and it can
include parts of trees (limbs), entire trees or groups of trees. Particulate organic matter
(POM — leaves, needles and small pieces of wood) transport can be considered a Geo-
morphology (Level 3) parameter, at least in terms of recruitment and transport; however,
since POM breaks down much faster than LWD, it fits better under organic processing,
which is a Physicochemical (Level 4) parameter. The distinction made here is that LWD is
a structural control and often included in geomorphology assessments, whereas, the
transport and processing of POM is often part of ecological assessments. For this reason,
LWD measurements are included in this section and methods for measuring organic
processing are included in the Physicochemical Chapter (Level 4).
Large woody debris is most prevalent in mountain streams (Rosgen stream types A
and B) and provides an important form of boundary roughness and flow resistance.
Additionally, LWD can increase localized bank erosion and, therefore, sediment supply;
produce a stepped channel profile where large pieces span the channel width; create
sediment and organic matter storage areas; provide cover for fish; and increase substrate
diversity (Wohl, 2000). In this role, LWD has a major influence on bed forms, sediment
transport and channel stability — clearly a Pyramid Level 3 parameter. It also provides
structure that is important for the processing of organic matter (Level 4 - Physicochemi-
cal) and supporting macroinvertebrate and fish health (Level 5 - Biology).
Measurement Method
There is an increasing amount of literature about the role and importance of LWD in
rivers. Montgomery et al. (2003) provides a good overview of the geomorphic effects of
wood in rivers with a global and historical overview. Abbe and Montgomery (1996) de-
scribe the role of LWD jams on channel hydraulics and habitat formations in large rivers
of the Pacific Northwest. Webster et al. (1999) describes the transport and breakdown of
allochthonous material at the Coweeta research forest, a Southeastern US watershed.
1. Wohl LWD Assessment
Wohl et al. (2009) published a recommended list of parameters and methods of mea-
surement to create a more standardized approach to measuring LWD. This list may be
more suited for stream assessments that are associated with research projects than those
for stream restoration. However, as noted in this document, many of these parameters
can be measured rapidly. Unfortunately, there have not been enough studies or assess-
ments completed using this method, and especially on high-quality streams, to create a
reference reach database and, therefore, a basis for developing performance standards.
A Function-Based Framework » May 2012 122
-------
Chapter 8: Geomorphology, Large Woody Debris Transport and Storage
Hopefully, that information will be available in the near future. A list of parameters and
measurement methods from Wohl et al. (2009) are provided at stream.fs.fed.us/publica-
tions/documentsStream.html. Level I lists metrics that the authors propose should be includ-
ed in all studies; Level II lists those metrics that are more applicable to a research project.
2. Large Woody Debris Index (LWDI)
While the research continues to evolve, Davis et al. (2001) provides a moderately rapid
and simple method of measuring LWD that includes a Large Woody Debris Index
(LWDI), making it a useful technique for comparing LWD functionality at a project reach
to a reference reach. Two stages of assessment of LWD and debris dams are described by
Davis et al. (2001). Stage 1 involves simply counting all LWD pieces and debris dams
within a reach and standardizing the count, based on reach length or sample area. In
addition to total counts of LWD and debris jams, stage 2 includes the single LWD piece
and debris dam size, compared to stream size, its position in the channel and the overall
stability of the LWD. The data collected in stages 1 and 2 are used to compute the LWDI.
Davis et al. (2001) also provide guidance on how to set up a monitoring program to
collect and evaluate the data, which generally include multiple samples that are statisti-
cally compared to a reference stream.
Performance Standard
Many restoration projects are beginning to incorporate LWD into their designs. This is
most prevalent in the Pacific Northwest, where practitioners are using engineered log
jams to restore floodplain connectivity, pool habitat and substrate diversity, as well as
reduce streambank erosion (Abbe et al., 2003). Rosgen (2010) is also incorporating more
wood into natural channel designs through the use of a toe-wood structure. Harman
(2004) shows techniques for using root wads and cover logs to increase wood in the
outside of meander bends. In these cases, performance may be measured based on the
stability of the structures post-restoration and flows that exceed the bankfull discharge.
To determine the overall performance of LWD on creating bed form diversity, organic
matter and nutrient retention, and channel stability, the LWDI index can be used. A
Functioning stream would have a LWDI that statistically has the same score as the
reference reach. A Not Functioning stream would have statistically significant lower value
than the reference stream with no evidence that the stream is trending towards a Func-
tioning condition, e.g., no buffer along the study reach or upstream. A Functioning-at-
Risk stream would also be statistically lower than the reference condition; however, the
trend is toward a Functioning condition, e.g., a buffer has been planted or is already
established and/or a wood supply exists upstream (Table 8.2).
A Function-Based Framework » May 2012 123
-------
Chapter 8: Geomorphology, Channel Evolution
TABLE 8.2 LARGE WOODY DEBRIS PERFORMANCE STANDARDS
MEASUREMENT
METHOD
Large Woody Debris
Index (LWDI)
FUNCTIONING
LWDI of project
reach equals
LWDI of
reference reach
FUNCTIONING-
AT-RISK
LWDI of project reach
does not equal
reference reach, but is
trending in that
direction.
NOT FUNCTIONING
LWDI of project reach
does not equal LWDI
of reference reach
and is not trending in
that direction.
8.4 » PARAMETER: CHANNEL EVOLUTION
Description
Channel evolution occurs when a stream system begins to change its morphology
from one condition or stream type to a new condition or stream type. Channel evolution
can be a negative or positive trend. As described by Leopold (1994), a stream system is a
"transporting machine" for water and sediment. An open system, such as a stream, will
attempt to work toward two end goals: (1) to perform a minimum amount of work and (2)
to expend energy uniformly. A stream system that is in equilibrium is one where these
goals are balanced (Leopold, 1994).
Channel evolution can be the result of a channel changing to a more stable or efficient
form. This is commonly seen in stream restoration where new channel geometry is
altered to a more stable form. Restored channels are typically constructed so that they
can improve (evolve) their functional capacity over time. In a meandering stream, this
generally corresponds to an evolution from a Rosgen C stream type to an E. An example
of this process is shown below in Figures 8.3 and 8.4. Figure 8.3 is a 2002 photo of a riffle,
taken a few months after construction and a bankfull event. Note the deposition on the
right bank (left side of photo). Figure 8.4 is a photo of the riffle in 2006 after the vegeta-
tion has become more established.
The channel evolved from a C stream type with a bankfull width/depth ratio of 14 in
2003 to an E stream type in 2007, with a bankfull width/depth ratio of 9. The cross section
in Figure 8.5 (below) represents the riffle. The deposition on the right bank is a natural
levee that was formed between the upstream point bar and the riffle section. There was
toe erosion along the left bank; however, the riffle evolved in a positive direction as
shown by the decrease in bankfull width/depth ratio, while maintaining a BHR near 1.0.
Channel evolution can also be the result of a disruption to the stream or watershed. If
a disruption to either the amount of stream power (such as from a change in slope or
discharge) or to the work to be done (such as a change in the amount of sediment supply),
the stream's equilibrium may be disturbed, and the stream channel may begin evolving
to meet the new conditions. This relationship was first described by Lane (1955). Lane's
diagram states that the sediment size multiplied by the sediment load is proportional to
the stream discharge multiplied by the slope (Figure 8.6).
A Function-Based Framework » May 2012
124
-------
Chapter 8: Geomorphology, Channel Evolution
FIGURE 8.3 RESTORED RIFFLE IN 2002
Source: Reproduced with permission from Michael Baker Corporation
FIGURE 8.4 RESTORED RIFFLE IN 2006
Source: Reproduced with permission from Michael Baker Corporation
A Function-Based Framework » May 2012
125
-------
Chapter 8: Geomorphology, Channel Evolution
FIGURE 8.5 EVOLUTION OFTHE RIFFLE CROSS SECTION FROM 2003TO 2007
Source: Reproduced with permission from Michael Baker Corporation and Wildland Hydrology
A common sequence of physical adjustments (channel evolution) has been observed in
many streams following disturbance. Disturbance can result from channelization, which
is an increase in runoff due to build-out in the watershed, removal of streamside vegeta-
tion or other changes that negatively affect stream stability. These disturbances occur in
both urban and rural environments. Several models have been used to describe this
process of physical adjustment for a stream.
The channel evolutionary stage conveys important information about the pressures on
stream systems and the stream channel's response. Stream and river restoration projects
often have an end goal of stabilizing the stream system, i.e., bringing the system into
equilibrium. In order to prevent or correct stream stability issues the current evolutionary
stage of the channel, and the pressures acting upon it must be understood.
Measurement Method
Understanding channel evolution is helpful during geomorphic assessments, restora-
tion goal setting and project evaluation. Channel evolution can be used during the geo-
morphic assessment phase to determine whether the stream reach is trending towards
stability or instability. This determination helps to establish better goals. If the stream is
trending towards stability (late stage of evolution), then the restoration goals can be more
A Function-Based Framework » May 2012
126
-------
Chapter 8: Geomorphology, Channel Evolution
FIGURE 8.6 GRAPHIC REPRESENTATION OF LANE'S DIAGRAM
The sediment size and load is shown on the left, and discharge and slope (power) is shown on the right. When
one of these parameters changes, there is often a change in streambed elevation. For example, an increase in
channel slope from channelization often leads to degradation.
25 (eel/mile | | 500
slrtNim slops' I 11 I I I I I I I I
O sediment size
Source: Reproduced with permission from Michael Baker Corporation
passive. These passive approaches often include land use management changes or simply
re-establishing a wide riparian buffer. If the stream is stable but is showing signs of
instability (early stage of channel evolution)
like the early signs of a headcut, then the goal
may be to simply stabilize the headcut to pre-
vent further upstream damage. Full-scale
restoration goals are often needed for streams
that have been disturbed and are evolving
towards increasingly unstable conditions or
reaches that will require many years of
adjustment before reaching equilibrium. Channel evolution can then be used after resto-
ration to help show that the stream is moving from a newly constructed condition to a
reference condition, e.g., a C evolving to an E.
If the stream is trending
towards stability (late stage
of evolution), then the
restoration goals can be
more passive.
A Function-Based Framework » May 2012
127
-------
Chapter 8: Geomorphology, Channel Evolution
Channel evolution can be assessed using Simon's Channel Evolution Model, Rosgen's
Stream Type Succession Scenarios or both. Both methods involve assessing the stream in
its current condition and determining its evolutionary endpoint.
1. Simon Channel Evolution Model
The Simon (1989) Channel Evolution Model (Figure 8.7) characterizes evolution in six
steps, including:
1. Sinuous, pre-modified
2. Channelized
3. Degradation
4. Degradation and widening
5. Aggradation and widening
6. Quasi-equilibrium
The channel evolution process is initiated once a stable stream that is well connected
to its floodplain is disturbed. Disturbance commonly results in an increase in stream
power that causes degradation, often referred to as channel incision (Lane, 1955). Incision
eventually leads to over-steepening of the banks; and when critical bank heights are
exceeded, the banks begin to fail. Incision and widening continue as headcutting moves
upstream. Eventually the bed slope is reduced, and sedimentation from bank erosion
begins to fill the channel (aggradation). A new, low-flow channel begins to form in the
sediment deposits. By the end of the evolu-
Full-scale restoration tionary Pr°cess' a stab!e streai? §eomefy'
similar to those of undisturbed channels,
goals are often needed for forms in the deposited alluvium. The new
Streams that have been channel is at a lower elevation than its
disturbed and are evolving original form, with a new floodplain con-
structed of alluvial material (FISRWG, 1998).
The first step toward determining the
Conditions Or reaches that channel evolution using this method is to
will reouire many years characterize the channel in its current
of adjustment before cond*T Th!s m;y mvolve;sm§similar
morphological indicators to determine
vertical and lateral stability, as well as
reviewing sediment transport calculations,
as described in the Rosgen (2006) method. Then an evolutionary stage from Simon's
model can be selected. For example, a newly channelized stream corresponds to Stage 2
of the Simon model. If an active headcut is observed in this channelized stream, it indi-
cates vertical instability, which corresponds to Stage 3 of the Simon model. If BHRs are
high, indicating incision, the stream may begin to have rotational and slab bank failure
from the changes in bank hydrostatic pore pressure caused by the drop in the water table.
This will cause the channel to widen, which would indicate that the stream is in Stage 4
A Function-Based Framework » May 2012 128
-------
Chapter 8: Geomorphology, Channel Evolution
FIGURE 8.7 SIMON CHANNEL EVOLUTION MODEL
Class I, Sinuous, Premodified
hhc
terrace
slumped material
Class V, Aggradation and Widening
h>hc
terrace
Class VI, Quasi Equilibrium
h
-------
Chapter 8: Geomorphology, Channel Evolution
of the Simon model. Stage 4 also corresponds to an increase in width to depth ratios. As
the stream continues to widen the slope decreases from down-cutting, the channel loses
the capacity to transport the sediment received. Depositional features, such as mid-chan-
nel and transverse bars, begin to develop, which force velocity vectors towards stream-
banks and cause increased bank erosion or widening. This is Stage 5 of the Simon model.
The level of effort and complexity for using the Simon Channel Evolution Model
varies depending on a qualitative versus a quantitative assessment. An experienced
practitioner can predict the stage of evolution by simply observing the channel, making
the level of effort "rapid" and level of complexity "simple." If field measurements are
taken, the level of effort and complexity increase to moderate (Appendix Ac).
2. Rosgen Stream Type Succession Scenarios
Rosgen (2006) uses changes in stream type to illustrate channel evolution. These
changes were measured in streams throughout the US. Nine different stream type succes-
sion scenarios are shown in Rosgen (2006). Since that publication, three more scenarios
have been added, and all 12 are shown below in Figure 8.8 (Rosgen, 2010, personal
communication). Scenario 5 most closely matches the Simon (1989) approach.
The first step toward determining the channel evolution with this method is to clas-
sify the channel using the Rosgen (1994) methodology. After determining the stream
type, observations should extend to the valley to determine what the naturally forming
stream type is for the given valley. Rosgen (1996) provides information regarding which
stream types occur naturally in certain valleys. Knowing the naturally occurring, stable
stream type provides the potential evolutionary starting and/or end point for the stream.
The next step in determining the channel evolution is to determine if the stream is
already at its evolutionary end point, or if it is in one of the stages of evolution. Morpho-
logical indicators can give clues as to whether a channel is vertically unstable, laterally
unstable or both. These include the presence (or absence) of features such as headcuts and
depositional bars; the presence and location of bank erosion; and geomorphic channel
measurements, such as bank height ratio, entrenchment ratio and width to depth ratio.
These indicators provide insight into whether the channel is aggrading or degrading.
These observations are then compared to sediment competency calculations to determine
whether the bankfull flows have the force to entrain the sediment delivered by the water-
shed, or if they have excessive force and may mobilize the entire bed. Rosgen (2006)
provides a detailed assessment method, which includes a series of geomorphology-based
worksheets used to determine channel stability. After the geomorphic and stability data
are gathered, the appropriate evolutionary sequence can be selected from one of the 12
scenarios shown in Figure 8.8. These determinations can be made visually by an experi-
enced practitioner and can, therefore, be completed rapidly. However, they can also be
measured, which increases the level of effort and complexity to moderate (Appendix Ac).
A Function-Based Framework » May 2012 130
-------
Chapter 8: Geomorphology, Channel Evolution
FIGURE 8.8 ROSGEN EVOLUTION MODEL BY STREAM TYPE
Various Stream Type Succession Scenarios
6.
7.
G
B
U
Eb
V
• B
C —* G - — F
>T*?tt
••>"?<•>-_/ .'••.'•••.•'
INCISED and AGGRADING to a FILL TERRACE
Source: Reproduced with permission from Wildland Hydrology
A Function-Based Framework » May 2012
131
-------
Chapter 8: Geomorphology, Channel Evolution
Performance Standard
Channel evolution as a performance standard is different than most of the other
parameters in that it is a summary condition that integrates several parameters and
processes. As such, it may be tempting to
use channel evolution as the only perfor-
mance standard in the Hydraulic and Geo-
morphology categories, stating for example
that a Rosgen C stream type is Functioning
and therefore meets the performance stan-
dard. This approach is strongly discouraged
because stream type alone does not provide
stability and functional capacity informa-
tion. There are many C and E stream types
that are Functioning-at-Risk or Not Func-
tioning. Keep in mind that a channel could
have a bank height ratio of 1.8, a very
incised channel, and still classify as a C or E.
The reason for including channel evolu-
tion is to show the current channel condi-
tion and how it could change over time. The
federal mitigation rule suggests that perfor-
mance standards be based on data from
reference reach streams. One reason for this
is to show the natural range of variability
that exists in stable, functioning streams.
The rule also states that performance stan-
dards should show the expected stages of
the aquatic resource development process, in order to allow early identification of poten-
tial problems and appropriate adaptive management. Channel evolution can be used
along with other parameters to show the expected stages of development in a restoration
project. For example, many projects are designed and built as a C stream type. Over
time, the channel evolves to an E stream type. Showing this evolution indicates that the
stream is trending towards a higher degree of functionality. A restored channel that is
built as a C stream type but begins to evolve to a Gc stream type represents a negative
trend, one that leads to instability and a loss of function. This project would require
immediate attention.
Tables 8.3 and Table 8.4 summarize the various stages for each measurement method
and whether they are Functioning, Functioning-at-Risk or Not Functioning. The arrow
(->) means that the stream type is changing from the former to the latter. For example, a
C-»Gc means that the current stream type is a C, and the stream is trending towards a
Gc. This table can be used as an aid in performing geomorphic assessments, goal setting
and for evaluating stream restoration projects.
Channel evolution as a
performance standard is
different than most of the
other parameters in that it is
a summary condition that
integrates several parameters
and processes. As such, it
may be tempting to use
channel evolution as the
only performance standard
in the Hydraulic and
Geomorphology categories.
This approach is strongly
discouraged because stream
type alone does not provide
stability and functional
capacity information.
A Function-Based Framework » May 2012
132
-------
Chapter 8: Geomorphology, Channel Evolution
TABLE 8.3 PERFORMANCE MEASUREMENT FOR ROSGEN'S STREAM TYPE
EVOLUTIONARY STAGES
MEASUREMENT METHOD
FUNCTIONING
FUNCTIONING-
AT-RISK
NOT FUNCTIONING
Rosgen's Stream Type Succession Scenarios
_ _ _
1 . b L/ (jC r L b
2. C^D^C
3. C->D->Gc->F->C
4. C-»G-»F-»Bc
5. E^Gc^F^C^E
6. B-»G-»Fb-»B
7. Eb-»G-»B
8. C^G^F^D^C
9. C^G^F^C
10. E-»A-»G-»F-»C-»E
11. C-»F-»C-»F-»C
P _ c p p p
_ ^ *J I" C C C
Ep
, ^
C
C
C, Be
E, C
B
Eb, B
C
C
E
First and last C
hirst ana last L
Ck f~* i~ -5 t~trl C k P
^uc ana I *L
C-»Dand D-»C
C-»D and F-»C
C-»G and F-»Bc
E-»Gcand F-»C
B-»G and Fb-»B
Eb-»G and G-»B
C-»G and D-»C
C-»G and F-»C
E-»Aand F-»C
C-»F
C.r* --.-j p_»p
^(3 ana L^L
(~*r* C
uC, r
D
D, Gc, F
G,F
Gc, F
G, Fb
G
G, F, D
G, F
A,G,F
F
Gc CJ-M i»-+i-» r*
,r, hourtn L
TABLE 8.4 PERFORMANCE MEASUREMENT FOR SIMON'S CHANNEL EVOLUTION STAGES
Simon (1989) Channel Evolution Model Stages
1. Sinuous, pre-modified
2. Channelized
3. Degradation
4. Degradation and widening
5. Aggradation and widening
6. Quasi-equilibrium
FUNCTIONING
•/
•/
FUNCTIONING-
AT-RISK
•/ *
NOT FUNCTIONING
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
variable (parameter) responds to the change in stream type. An up arrow means that there
is an improvement, a down arrow means that there is a functional loss, and a sideways
arrow indicates no change. The green shading indicates that these two stream type
evolutionary changes are positive or, using Performance Standard terminology, Function-
ing-at-Risk. Once they evolve to a C or E stream type, they will be Functioning.
TABLE 8.5 THE EFFECTS OF STREAM TYPE CHANGES ON HABITAT PARAMETERS
Variable
Instream Cover
Overhead Cover
Substrate Composition
Pool Quality
Holding Cover Velocity
Temperature
Oxygen
Macro Invertebrates
Spawning Habitat
Diversity
Rearing
IBI Score
C->G
4-
i
1
sj/
j*
->
-»
i
I
4-
J
i
G^F
±
£
4,
i
i
t
i
i
i
i
t
&
C->D
±
i
i
±
±
t
i
4>
^
4-
t
i
F->C
t
t
t
t
t
±
t
t
t
t
t
t
C-}E
t
t
t
t
t
i
t
t
t
t
t
t
Source: Reproduced with permission from Wildland Hydrology
8.5 » PARAMETER: BANK MIGRATION/LATERAL STABILITY
Description
Lateral stream migration commonly occurs on rivers that flow through alluvial valleys.
A channel migrates within the floodplain through lateral erosion on the outside of mean-
der bends and subsequent deposition on the interior bend, or point bar. In order to under-
stand bank migration and lateral stability, energy expenditure in a stream system should
be addressed first. Streams and rivers are open systems, which have a continual source of
potential energy supplied by topographic elevation and precipitation (the hydrologic
cycle). The potential energy supplied by the rain and elevation is transformed to kinetic
energy as water flows downhill. The kinetic energy carries sediment downstream (sedi-
ment transport) and causes some erosion from turbulence and friction along the channel
boundary. In an alluvial valley where the boundary conditions (bank materials) are
erodible, meanders will form and continue to erode until the stream achieves a plan form,
where energy is expended uniformly and the least amount of work possible is accom-
plished (Leopold, 1994). Once this equilibrium is achieved, a stream may continue to
A Function-Based Framework » May 2012
134
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
migrate but will deposit materials in bars to maintain the bankfull cross-sectional area.
Bank migration and lateral stability are as much a function of the bank materials and
bank cover as they are the in-stream hydraulic forces acting upon them. This is because
bank materials and vegetative cover resist hydraulic forces, such as shear stress. A barren
bank composed primarily of sand, for example, is more susceptible to erosion than a
densely vegetated clay bank. In addition, some stream types are naturally more suscep-
tible to bank erosion than other stream types. Stream types A and B are less likely to
experience extreme bank migration because of their confined valleys and steep vertical
profiles, often controlled by bedrock or colluvium. Stream types C and E are more likely
to experience bank migration since these stream types are by nature sinuous, meandering
stream channels, which actively migrate across floodplains. Stream types F and G are
often associated with excessive bank erosion because they are entrenched. Bank erosion
within these stream types can be extreme in disturbed systems where the former stream
type was a C or E (see section on Channel Evolution). However, F and G stream types
associated with bedrock-controlled gorges may be stable. Rosgen (1994) provides a table
(Table 8.6) showing the sensitivity to lateral adjustment and recovery potential. In this
example, recovery potential means the ability of the stream to return to a laterally stable
condition without human intervention.
TABLE 8.6 Rosgen (1994)
Illustrates the sensitivity to disturbance, recovery potential, typical sediment supply conditions, streambank
erosion potential and the influence of bank vegetation on stability for a wide range of stream types.
Stream Type
A1
A2
A3
A4
A5
A6
B1
B2
B3
B4
B5
B6
C1
C2
C3
C4
C5
C6
Sensitivity to
disturbance3
Very low
Very low
Very high
Extreme
Extreme
High
Very low
Very low
Low
Moderate
Moderate
Moderate
Low
Low
Moderate
Very high
Very high
Very high
Recovery
potential15
Excellent
Excellent
Very poor
Very poor
Very poor
Poor
Excellent
Excellent
Excellent
Excellent
Excellent
Excellent
Very good
Very good
Good
Good
Fair
Good
Sediment
supply0
Very low
Very low
Very high
Very high
Very high
High
Very low
Very low
Low
Moderate
Moderate
Moderate
Very low
Low
Moderate
High
Very high
High
Streambank
erosion
potential
Very low
Very low
Very high
Very high
Very high
High
Very low
Very low
Low
Low
Moderate
Low
Low
Low
Moderate
Very high
Very high
High
Vegetation
controlling
influenced
Negligible
Negligible
Negligible
Negligible
Negligible
Negligible
Negligible
Negligible
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Very high
Very high
Very high
Very high
A Function-Based Framework » May 2012
135
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
TABLE 8.6 Rosgen (1994) (CONT.)
Illustrates the sensitivity to disturbance, recovery potential, typical sediment supply conditions, streambank
erosion potential and the influence of bank vegetation on stability for a wide range of stream types.
Stream Type
D3
D4
D5
D6
Da4
DAB
DA6
E3
E4
E5
E6
F1
F2
F3
F4
F5
F6
G1
G2
G3
G4
G5
G6
Sensitivity to
disturbance3
Very high
Very high
Very high
High
Moderate
Moderate
Moderate
High
Very high
Very high
Very high
Low
Low
Moderate
Extreme
Very high
Very high
Low
Moderate
Very high
Extreme
Extreme
Very high
Recovery
potential15
Poor
Poor
Poor
Poor
Good
Good
Good
Good
Good
Good
Good
Fair
Fair
Poor
Poor
Poor
Fair
Good
Fair
Poor
Very poor
Very poor
Poor
Sediment
supply0
Very high
Very high
Very high
High
Very low
Low
Very low
Low
Moderate
Moderate
Low
Low
Moderate
Very high
Very high
Very high
High
Low
Moderate
Very high
Very high
Very high
High
Streambank
erosion
potential
Very high
Very high
Very high
High
Low
Low
Very low
Moderate
High
High
Moderate
Moderate
Moderate
Very high
Very high
Very high
Very high
Low
Moderate
Very high
Very high
Very high
High
Vegetation
controlling
influenced
Moderate
Moderate
Moderate
Moderate
Very high
Very high
Very high
Very high
Very high
Very high
Very high
Low
Low
Moderate
Moderate
Moderate
Moderate
Low
Low
High
High
High
High
a Includes increases in streamflow magnitude and timing and/or sediment increases.
b Assumes natural recovery once cause of instability is corrected.
c Includes suspended and bedload from channel derived sources and/or from stream adjacent slopes.
d Vegetation that influences width/depth ratio-stability.
Measurement Method
Bank migration can be measured a variety of ways, ranging from rapid and simple
methods to intensive and complex. This document provides examples from simple
interpretations of aerial photographs to complex computer models. These measurement
methods are listed in progressive order, from simple to complex.
A Function-Based Framework » May 2012
136
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
1. Meander Width Ratio
Meander width ratio is the ratio of stream belt width divided by stream bankfull
width. The belt width is the distance from the apex of one meander bend to the next
meander bend, measured perpendicular to the fall line of the valley (Figure 8.9). To
compare belt widths between different size streams, the belt width is divided by the
bankfull width to create a dimensionless ratio. The minimum meander width ratio for
meandering streams (C and E stream types) is between 3.0 and 3.5; this ratio is required
to create a sinuosity of at least 1.2, the most common break point between meandering
and non-meandering streams (Rosgen, 1996; Leopold and Wolman, 1957). If a straight-
ened stream is eroding on both banks and readjusting its pattern, the bankfull width
(measured from the aerial) can be multiplied by 3.5 (conservatively) to estimate the
amount of lateral erosion that will likely occur.
Meander width measurements can rapidly be taken from existing engineering plans,
topographic maps and aerial photographs. Aerial photography, unlike other methods providing
information about lateral stability and bank erosion on a local, short-term scale, can be
used to determine lateral stability over a much longer time frame and over great distanc-
es. Historic aerial photography can be overlaid with current photography to determine
the degree of lateral migration that has occurred between the dates of the photographs.
Digital orthophotos can usually be purchased from local or state governments and are
preferred over some free Web services that do not provide geo-corrected photographs.
Using aerial photography to determine lateral stability has its benefits. For relatively
low cost and time expenditure, aerial photography affords long-term views of the stream
channel position in the floodplain. It can also provide information about whether the
channel migrated rapidly or slowly in the past, and whether a local or watershed distur-
bance, such as deforestation, is correlated to the channel migration changes. A limitation
to aerial photography is that it only provides plan view information, i.e., it is not possible
to calculate the volume of eroded sediment without a field measurement of the bank
height or more advanced techniques for reading aerial photos. Aerial photograph analysis
combined with reference reach surveys can be used to determine the ultimate belt width
of an unstable C or E stream type.
2. BEHI/NBS
Rosgen's Bank Erosion Hazard Index (BEHI) and Near Bank Stress (NBS) rating meth-
ods can be used to estimate the annual amount of lateral erosion/migration. These
methods involve collecting relatively simple measurements and visual observations of
streambanks, including bank cover, depth of root mass, channel composition and bank
slope; then a BEHI risk rating is assigned, from very low to extreme. Observations of
channel flow characteristics, including water-surface slope, direction of velocity vectors
and other methods, are used to assess the NBS risk rating, which can range from very
low to extreme. These ratings can be used with a streambank erodibility rating curve,
appropriate for the area, to derive a predicted annual linear footage of bank erosion per
year. A detailed description of this method is in Rosgen (2009). The BEHI/NBS assess-
A Function-Based Framework » May 2012 137
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
FIGURE 8.9 PATTERN MEASUREMENTS AND RATIOS, INCLUDING THE MEANDER WIDTH
WBKF
RADIUS OF
CURVATURE (RC)
MEANDER LENGTH (LM)
CHANNEL PATTERN CALCULATIONS
RADIUS OF CURVATURE/RIFFLE WIDTH (RC/WBKF)
MEANDER LENGTH / RIFFLE WIDTH (LM /WBKF)
MEANDER WIDTH RATIO (MWR = WBLT/WBKF)
SINUOSITY (K) = CHANNEL LENGTH (CD /VALLEY LENGTH (VL)
ment can be completed with a moderate level of effort if the practitioner is not quantita-
tively measuring every bank, but rather makes qualitative predictions with periodic
measurements for calibration. If the practitioner is using bank pins and cross sections (see
below) to develop BEHI/NBS curves, the level of effort increases to intensive (Appendix Ac).
3. Bank Pins
Another method for measuring lateral stability or bank erosion/migration is through
the installation of bank pins. Bank pins are usually long steel rods (rebar) installed flush
with the streambank. The pins are installed at known intervals from the toe of the bank
to the top of the bank. Each time the site is visited, the length of exposed rebar is mea-
sured and can be combined with the distance between pins to provide a square-footage
of bank material lost.
Using bank pins to perform annual monitoring of bank erosion is beneficial due to the
relatively low cost and time required. Unfortunately, this method provides information
about the eroding bank only and fails to capture information about developing bars (if
any). Although visual observations of developing bars can be made, it is difficult to
determine whether the erosion and deposition are balanced, and whether the channel is
maintaining dimension, despite erosion. More information about banks pins can be
found in Harrelson el al. (1994).
A Function-Based Framework » May 2012
138
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
4. Bank Profiles
Bank profiles provide detailed information about lateral stability and bank erosion at a
particular bank. These profiles involve installing permanent cross-section markers, as
discussed in Cross-Sectional Surveys (below), as well as a permanent toe pin marker. The
toe pin should be installed at the base of the study bank to ensure that the bank profile is
taken in the same location each time. Surveys of the bank are conducted each time the
site is visited. Detailed instructions about performing bank profiles are provided by
Rosgen (2009).
One benefit to conducting a bank profile survey, as opposed to installing and measur-
ing bank pins, is that a survey captures more detailed information about the bank, allow-
ing for a more precise measurement of bank material lost due to erosion. A bank profile
also causes virtually no disturbance to the bank, as opposed to bank pins that require
hammering rods into the bank. Some researchers believe that bank pin installation
compromises the integrity of the bank, resulting in more erosion than would typically
occur if the bank were undisturbed.
FIGURE 8.10 OVERLAY OFTWO BANK PROFILES FROM WATTS BRANCH
100
I 95
—
w
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
An example of two bank profiles measured at the same location and overlaid with each
other is shown in Figure 8.10. The figure shows a lateral erosion rate of 1.4 feet, which
was calculated as the difference in area between the two curves, divided by the bank
height. To measure the total amount of bank erosion in ft3/year, the lateral erosion rate
can be multiplied by the bank height and length that is representative of the profile.
5. Cross-Sectional Surveys
Lateral stability and bank erosion/migration can also be measured and monitored
through cross-sectional surveys. Cross sections should be defined through installation of
permanent markers denoting the beginning and end point of the survey to ensure the section
is repeated in the same place each time. Cross sections from year to year can be overlaid
and the distance of bank migration can be measured. Unlike bank pins and bank profiles,
cross sections provide information about the channel bed and the opposite bank, so deposition
or erosion across the entire section can be observed. This can be very useful in helping
determine whether lateral erosion is a result of a stable but active and dynamic channel,
or if it is the result of a stream out of equilibrium. Also useful is the ability to determine
if there has been a change in cross-sectional area, width or depth, as a result of lateral
erosion and/or deposition within the section. This provides insight into whether the bank
migration is a result of natural migratory processes, or whether it is a result of stream
disequilibrium. Detailed information on performing cross-sectional surveys can be found
in Harrelson et al. (1994) and Rosgen (2009). An example of two cross sections measured
at the same location one year apart is shown below in Figure 8.11. The overlay shows that
the right streambank has laterally eroded 15 feet. The point bar location has remained the
same, indicating that the bankfull channel width and cross-sectional area is increasing.
FIGURE 8.11 CROSS-SECTIONAL SURVEYS OF AN ERODING STREAMBANK
1122
1108
1106
50
100 150
Station (Feet)
200
250
300
350
•1998
-1997
Source: NC State University, Stream Restoration Program
A Function-Based Framework » May 2012
140
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
6. Bank Stability and Toe Erosion Model
Andrew Simon and Eddy Langendoen (2006) developed a computer model that can be
used to estimate the potential for bank failure — or lateral instability — from horizontal
layer, vertical slice with tension crack, or cantilever failures. The model requires detailed
input information about the streambank, including the various soil layers and profile, the
water table and stream level, the bank profile, and vegetation present on the bank. The
model outputs a factor of safety that corresponds to the potential for bank failure. Due to
the amount of data that needs to be collected and entered into the model, this is one of
the more complex methods of predicting lateral stability.
Performance Standards
Thresholds for determining whether a stream is Functioning from a bank migration or
lateral stability standpoint should be considered with stream channel type and channel
evolutionary stage in mind. In general, it is good to compare what is observed in the field
with what is known about stable reference reach conditions. There are several different
methods for measuring lateral instability; therefore, the performance standards for each
are broken down by measurement method. The performance standards provided below
are most applicable to Be, C, E, F and Gc stream types.
1. Meander Width Ratio (MWR)
The Meander Width Ratio (MWR), described above, can be used to determine wheth-
er a stream channel is Functioning from a lateral stability perspective. Each stream type
has an accepted range of MWRs, as determined from reference reach surveys. MWRs
determined from aerial photography can then be compared to known ranges for stable
reference reach streams to establish whether the stream is Functioning. Typical ratios for
C and E stream types are shown in Table 8.7.
A minimum MWR of 3.0 to 3.5 is critical A minimum MWR of 3.0 to 3.5
for stream restoration projects that include /s cr/f/ca/ for stream restora-
new channel construction. If a C or E stream
type is designed and constructed with a
MWR below 3.0, there is a high risk of bank channel construction. If a C or
erosion and reach wide instability. In these £ stream type IS designed and
cases, the restoration practitioner is trying to constmcted with g MWR
force a meandering channel in a confined
corridor. Confinement is usually caused by
land availability rather than geologic controls, of bank erosion and reach
These streams typically have sinuosity less wide instability
than 1.2 and do not classify as meandering
streams. The result is that the stream begins to straighten through bank erosion that
extends from the outside of the meander bend downstream to the next point bar. A range
of 3.0 to 3.5 is used in the Functioning-at-Risk category because a sinuosity of 1.2 can
typically be achieved with this range. For example, W/D ratios less than 12 can often
A Function-Based Framework » May 2012 141
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
achieve the minimum sinuosity of 1.2 with a MWR of 3.0. Higher W/D ratio streams
need a MWR of 3.5. Generally, higher MWRs lead to higher functionality (longer riffles
and more stream length), as long as the sinuosity does not lower the slope to a point
where the channel aggrades.
2. Lateral Erosion (BEHI/NBS)
BEHI and NBS scores can be used to determine thresholds for Functioning, Function-
ing-at-Risk and Not Functioning. However, a reach wide assessment of bank erosion
should be conducted to determine overall functionality from a bank stability perspective.
For example, a large tree could fall into a stream creating an unstable bank, perhaps with
a high BEHI score and an Extreme NBS score; this would cause the bank to fall into the
Not Functioning category. But if the buffer width is sufficient and the banks are well
vegetated upstream and downstream of the unstable bank, it is unlikely that the bank
erosion will worsen. It will likely heal over time because the overall reach is stable and
Functioning. If the buffer is not well established, it is possible that the bank will erode for
a long time before it becomes stable and could lead to pattern adjustment and instability
for a longer portion of the reach.
The thresholds shown in Table 8.7 came from a review of the erosion rate curve
provided by Rosgen (2001). This curve was developed in Colorado (Figure 8.12), so these
ranges could be modified based on locally developed curves. The Rivermorph software
package provides erosion rate curves for other parts of the US.
Table 8.7 shows the BEHI categories/curves as rows and the NBS rating in the indi-
vidual columns for Functioning, Functioning-at-Risk and Not Functioning. The Colorado
erosion rate curve shown in Figure 8.12 was used as a guide to determine the level of
functionality. In general, if the curve predicted below 0.1 ft/year, a Functioning category
is shown. If the erosion rate fell between 0.1 and 0.5 ft/yr, a Functioning-at-Risk category
was shown. Not Functioning categories were assigned to curves that predicted above 0.5
ft/yr. This curve was only used as a guide, however, as some curves deviate from this
range based on the slope of the curve and its relationship to other curves. Again, these
classifications can be modified based on locally generated curves and their comparison to
reference reach data.
3. Lateral Erosion (Bank Profile)
Bank profiles provide an actual measurement of erosion in feet/year. Therefore, perfor-
mance standards can be created based on those measurements as long as several years of
data are available that represent varying weather conditions, including bankfull events.
The performance standards should be developed from reference streams for the Function-
ing category, moderately eroding streambanks for Functioning-at-Risk, and highly erod-
ing for Not Functioning. These values are then compared to the erosion rates from project
streams, providing an estimate of functional capacity. Typical values for Functioning,
Functioning-at-Risk and Not Functioning are provided in Table 8.7. These values are
based on the Colorado erosion rate curve shown in Figure 8.12 and data collected by the
A Function-Based Framework » May 2012 142
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
FIGURE 8.12 EROSION RATE CURVES BASED ON BEHI AND NBS SCORES IN COLORADO
10
EXTREME BEHI
BER = 0.0642e°9M1NBS
HIGH & VERY
HIGH BEHI
= 0.109e°"
MODERATE BEHI
= 0.0556e°505"N8S'
LOW BEHI
= 0.0082eon49(NBSI
0.01
Very Low Low Moderate High Very High Extreme
0 1 2 3 4 5 ' 6
Near-Bank Stress (NBS)
Source: Reproduced with permission from Wildland Hydrology
A Function-Based Framework » May 2012
143
-------
Chapter 8: Geomorphology, Bank Migration/Lateral Stability
authors in North Carolina streams. They are typical values and can be adjusted based on
local site conditions.
It should also be noted that these values came from an assessment of a short length of
streambank and are not representative of the overall reach length. Many reference reach
streams that would be considered laterally stable will have varying levels of bank erosion.
Most of the streambanks will be stable with erosion rates similar to what is shown in
Table 8.7; however, there may be short sections that have higher erosion rates. If the
erosion is localized and will not lead to further instability or reach wide instability, the
overall reach should still be considered Functioning.
4. Lateral Erosion (Cross Sections)
Cross-sectional data can give a broader perspective of functionality than the bank
profiles, and they are often used together to assess lateral erosion and instability. Cross-
sectional data can be used to calculate bankfull cross sectional, area, width and mean
depth. From these data, the bankfull width/depth ratio can be calculated as the bankfull
width divided by mean depth (W/D). Increases in the W/D ratio are often associated
with accelerated bank erosion rates and bed aggradation (Rosgen, 2006). This informa-
tion is not provided by the bank profile. Rosgen (2009) developed a comparison of project
W/D ratios to reference reach W/Dref by simply dividing the W/D by the W/Dref. As the
ratio increases, the risk of bank erosion and bed aggradation increases. These values are
shown below in Table 8.7 and are used to determine functionality. The values are most
applicable to C stream types in Western states. In the Southeastern US, the values can
likely be increased slightly because most streams in alluvial valleys are E stream types. It
will take bigger changes in the W/D before bank erosion leads to aggradation.
5. Bank Stability and Toe Erosion Model
Simon and Langendoen's (2006) model calculates a Factor of Safety (Fs) value to
determine the lateral stability of a bank. The Factor of Safety can be used to establish the
functionality for the bank; however, the previous comments still apply. The overall reach
should be assessed to determine if the bank erosion is simply a localized problem or
symptomatic of a larger, system-wide problem.
A Function-Based Framework » May 2012 144
-------
Chapter 8: Geomorphology, Riparian Vegetation
TABLE 8.7 LATERAL STABILITY PERFORMANCE STANDARDS
MEASUREMENT
METHOD
FUNCTIONING
FUNCTIONING-
AT-RISK
NOT FUNCTIONING
Meander Width Ratio
for C and E stream
types
Lateral Erosion rate-
Low BEHI Curve
Lateral Erosion rate-
Moderate BEHI Curve
Lateral Erosion rate-
High and Very High
BEHI Curve
Lateral Erosion rate
- Extreme BEHI Curve
Lateral Erosion Rate
(Bank Pins and Bank
Profiles)
Lateral Erosion Rate
Potential for C4 streams
(W/Dproj/W/Dref*
Bank Stability and Toe
Erosion Model
> 3.5 (based on
reference reach
surveys)
Very low to
Moderate NBS
Very low to Low
NBS
N/A
N/A
Erosion rate is
similarto
reference reach
values, generally
< 0.1 ft/yr
1.0 to 1.2
Fs> 1.3
3.0 to 3. 5 as long
as sinuosity is
> 1.2
Moderate to Very
High NBS
Low to High NBS
Low to Moderate
NBS
Low NBS
0.1 to 0.5 ft/yr
1.2 to 1.4
1.0 1.3
0.5 ft/yr
= > 1.4
Fs< 1.0
* W/Dproj = Bankfull width divided by bankfull mean depth from the project reach
W/Dref= Bankfull width divided by bankfull mean depth from the reference reach
8.6 » PARAMETER: RIPARIAN VEGETATION
Description
The lateral migration parameters discussed above primarily focus on maintaining
streambank stability and do not evaluate the overall condition of the riparian buffer. The
BEHI/NBS method for predicting streambank erosion, for example, does include assess-
ments of streambank vegetation, but is only for the purpose of providing bank stability.
Riparian buffers or zones are the vegetated region adjacent to streams and wetlands that
are critical to providing channel stability, cover/shade, wood recruitment to the channel,
and a source of carbon (Sweeney, 1993; Hession et al., 2000; Sweeney et al., 2004; Hoff-
man, 2006; Sweeney and Elaine, 2007). Therefore, the restoration of riparian vegetation
as part of a Level-3 assessment and design approach provides the vegetative structure to
support many of the Level 3, 4 and 5 functions.
A Function-Based Framework » May 2012
145
-------
Chapter 8: Geomorphology, Riparian Vegetation
Research has shown that a well-managed restored buffer can trap and/or convert up to
75% of nitrogen and 70% of phosphorus from nonpoint source runoff, if the source is
from land uses that are adjacent to the stream corridor (Orzetti et al.; 2010; Claussen et
al.; 2000; Lee et al.; 2003; Schoonover and Williard, 2005). Additional research has shown
50% to 80% reductions in sediment loads from adjacent nonpoint source pollution
(Orzetti et al.; 2010; Cooper et al.; 1987; Daniels and Gilliam, 1996; Lowrance and Sheri-
dan, 2005; Schoonover and Williard, 2005; Tomer et al., 2007). Orzetti et al. (2010) went
on to show that habitat, water quality and benthic macroinvertebrate parameters im-
proved with the age of the restored buffer. In their study of 30 streams in the Piedmont of
Maryland and Virginia, habitat scores (measured using EPA Rapid Bioassessment Proto-
cols) stabilized between 10 and 15 years after restoration. In addition to habitat improve-
ments, the study showed improvements to water quality and macroinvertebrate commu-
nities within 5-10 years post-restoration, leading to conditions similar to mature buffers
within 10-15 years post-restoration. Mayer et al. (2005) provides a broader review of the
science and regulation of riparian buffers. This literature review focused primarily on
research related to nitrogen removal by riparian buffers. The study found that buffers
greater than 150 feet wide more consistently removed significant portions of nitrogen
entering the riparian zone. The study also found that in order to maintain buffer effec-
tiveness, buffer integrity should be protected against soil compaction, loss of vegetation
and stream incision. Stream incision is a key point because a lot of the dentrification
occurs through subsurface flow interacting with the root zone of the buffer. If the stream
becomes incised and the water table drops, the subsurface flow essentially bypasses the
buffer, not allowing dentrification to occur. The assessment of stream incision is part of
the Level 2 assessment of Hydraulic functions and the floodplain connectivity parameter.
It is important to note that buffer composition, density and function vary across the
country based on climatic and geologic differences. Many of the studies listed above
focus on hardwood forests in the Eastern US; however, bottomland hardwoods would
not be expected in prairie lands of the Great Plains and Midwest, or arid areas of the
Southwest. Reference reach analyses should be completed to determine the functional
capacity for a given region. Nevertheless, riparian buffers are important for providing
channel stability and supporting Level 4 and 5 functions, regardless of their setting.
For stream assessments and restoration projects, it is also important to identify the
potential impacts from land use and other stressors that may exist within and surround-
ing the riparian buffer area. Watershed disturbances, including livestock grazing, agricul-
ture and urbanization may have affected the soils and hydrology of the buffer and may
continue to be a challenge after restoration. Soil compaction and loss of soil fertility can
hinder riparian vegetation establishment and growth along with lowered water table
elevations. Land disturbance activities also increase the potential for invasive species
populations to affect the native vegetation and limit the riparian buffer function. Her-
bivory and beaver activities can also add pressure on riparian vegetation during establish-
ment and growth in certain watersheds. Although impacts and stressors may be difficult
to control outside the buffer area, stream restoration design should always consider these
A Function-Based Framework » May 2012 146
-------
Chapter 8: Geomorphology, Riparian Vegetation
factors when selecting vegetative species, specifying methods to improve soil conditions
and by attempting to reconnect the groundwater table to the riparian buffer root zone.
Vegetation maintenance plans are desirable that address these impacts and stressors for
the estimated duration of buffer function development.
Overall benefits provided by riparian buffers include:
1. Shade cover, which reduces both air and water temperature fluctuations due to sun
exposure within the riparian zone (Barton et al., 1985);
2. Organic matter contributions, including leaf litter that supports macrobenthos food
webs and woody debris that creates more diverse bed form and additional organic
matter (Dolloff and Warren 2003, Quinn et al., 2007, Opperman et al., 2004);
3. Dissipation of energy and capturing of sediment from upslope overland flow and
floodwater (Magette et al., 1989);
4. Nutrient uptake by roots of the riparian vegetation from groundwater moving
downslope, acting as a sink to limit what reaches the stream (Lowrance et al., 1984);
5. Stabilization of the streambank by roots that extend throughout the bank (Wynn et
al., 2004); and
6. Landscape connectivity for animals traveling along the stream corridor, connecting
patches of riparian habitats across the landscape (Fisher et al., 1998).
These are just some of the key benefits that a functioning riparian zone provides; more
details can be found in Knight and Bottorff (1984), and Naiman and Decamps (1997).
Measurement Method
Riparian buffers are often assessed by measuring the width, vegetation density, veg-
etation composition, age-class distribution, and growth and canopy density. Air and
water temperature may also be included as a method for assessing buffer functionality,
but these measurements are made as part of the Physicochemical assessment (Level 4).
Methods for measuring each of these parameters are described below. In addition, rapid
methods called the Proper Functioning Condition (PFC), EPA Rapid Bioassessment Proto-
col (RBP), NRCS Rapid Visual Assessment Protocol (RVAP), and USFWS Stream Assess-
ment Ranking (SAR) are described that can be used to determine the overall functionality
of the riparian corridor.
1. Buffer Width
Buffer width is measured from the top of the streambank (bankfull for restored reach-
es), perpendicular to the fall line of the valley and moving away from the channel. Buffer
width is sometimes expressed as an average width or a minimum width. An average
width is often used in meandering streams to keep the riparian corridor relatively
straight. The average width includes shorter distances at the meander bends and longer
distances from the point bar. Each measurement is added together and divided by the
total to get the average. The minimum width approach creates a buffer that meanders
A Function-Based Framework » May 2012 147
-------
Chapter 8: Geomorphology, Riparian Vegetation
with the channel and can be a challenge for establishing conservation easements or
fencing requirements.
An alternative approach for meandering streams is to measure the buffer width from
the belt width, rather than the top of the bank. The belt width is the distance from one
meander bend to the next, measured perpendicular to the fall line of the valley. In this
case, a best-fit belt width would be used to establish a straight corridor. The riparian
buffer width would be added to the belt width (Figure 8.13).
FIGURE 8.13 BUFFER WIDTH MEASURED FROM BELT WIDTH
BUFFER WIDTH LIMIT
BELT WIDTH LIMIT
T
NOTE
The buffer width limit is established as a parallel line to the belt width.
The minimum belt width is 3.5 times the bankfull width.
The minimum width from the belt width limit to the buffer width limit is
1 5 feet.
2. Buffer Density
Buffer density is defined as the number of stems per unit area, e.g., stems/acre. Density
is typically measured by establishing rectangular monitoring plots within the riparian
corridor. The total area of the plots should be statistically representative of the entire
buffer and should be well distributed throughout the buffer. Plots are surveyed annually
and include the total number of trees (stems) within the plot. The level of effort varies
from moderate to intensive depending on how the results are used. If the results are
A Function-Based Framework » May 2012
148
-------
Chapter 8: Geomorphology, Riparian Vegetation
compared to a reference condition so that additional measurements are not required, the
level of effort is moderate. If measurements are made annually and compared against
each other, then the level of effort is intensive (Appendix Ac).
3. Buffer Composition
In conjunction with determining the planted stems surviving year to year, the same
plot should be used to determine how species change within the plot. All trees that begin
growing in the plot should be identified and counted each year. A size should be deter-
mined above which the volunteer stems will be counted, in order to avoid the many
individuals that can start each year but will die before the next sample period. This data
should be expressed as total stems per area, percent planted and percent volunteer. This
data should also indicate if undesirable species are developing, such as exotic species.
Exotic species should be removed and not allowed to continue growing until the next
growing season. Like buffer density, the level of effort varies from moderate to intensive
depending on how the results are used. If the results are compared to a reference condi-
tion so that additional measurements are not required, the level of effort is moderate. If
measurements are made annually and compared against each other, then the level of
effort is intensive (Appendix Ac).
4. Buffer Age
The age-class distribution of vegetative cover should be evaluated to determine the
opportunity for recruitment, maintenance and recovery following flooding or other
disturbance. A diverse age-class distribution may also limit invasive species establishment
and their ability to out-compete native species. This distribution is particularly important
for shrub and tree species. Although recently established riparian buffers associated with
restoration projects will have minimal age-class distributions initially, the riparian buffer
should develop this characteristic over time to more resemble a reference condition for
the particular vegetative species established. The age of vegetative cover can be recorded
within similar monitoring plots used to determine buffer density and species composi-
tion. Buffer age and growth (below) are almost always measured periodically (typically
annually) and compared to previous measurements. Therefore, the level of effort is
intensive (Appendix Ac).
5. Buffer Growth
Buffer growth can be sampled by measuring stem diameter and height using the
methods of Lee et al. (2008). For stems less than 1.37 m in height, measure height (in cm)
and ddh (diameter at one decimeter height above the ground) to the nearest mm of the
thickest stem. For stems between 1.37 and 2.5 m in height, ddh and height are measured
as above, and stem DBH (Diameter at Breast Height or 1.37 m above the ground) is also
measured. For stems in excess of 2.5 m in height, DBH and height are measured, but not
ddh. These measurements can be used to express the basal area of woody stems that are
maturing within the riparian zone.
A Function-Based Framework » May 2012 149
-------
Chapter 8: Geomorphology, Riparian Vegetation
6. Canopy Density
The angular canopy density, which is an index of cover or shading by the foliage of
riparian trees, can be measured using a densiometer. The densiometer consists of a
convex mirror divided into grids that allows a visual estimate of the percent of the stream
or soil shaded by surrounding vegetation. The canopy density should be taken at the
same location and same height above ground each year, and multiple sample locations
should be used to provide an estimate of the entire restored riparian zone. The density of
the canopy should become greater each year, after about year five when trees begin to get
large enough to shade the stream and riparian zone. The level of effort varies from
moderate to intensive depending on how the results are used. If the results are compared
to a reference condition so that additional measurements are not required, the level of
effort is moderate. If measurements are made annually and compared against each other,
then the level of effort is intensive (Appendix Ac).
7. Proper Functioning Condition (PFC)
The Bureau of Land Management, with the assistance of other federal agencies, devel-
oped a quantitative rapid assessment method for evaluating proper functioning condition
for lotic areas. The document was prepared by Prichard et al. (1998) and is available
online at ftp.blm.gov/pub/nstc/techrefs/FinalU37-15.pdf. Proper Functioning Condition (PFC)
is both an assessment methodology and a condition that describes riparian-wetland areas.
As an assessment methodology, PFC evaluates hydrology, vegetation and erosion/deposi-
tion processes. A checklist is used to assess these functions and to determine the overall
health of the streambanks and riparian-wetland area. Therefore, PFC can be used to
assess lateral stability (Geomorphology functions), as well as the overall health of the
riparian corridor (Biology functions). As a condition, PFC describes how well the physical
processes are functioning in order to provide stability and habitat. A stream corridor that
is in a Proper Functioning Condition will remain stable during high flow events. This
resiliency allows an area to produce desired conditions over time, such as fish habitat,
neo-tropical bird habitat or forage. Riparian-wetland areas that are not functioning
properly cannot sustain these conditions.
PFC is less quantitative than bank profiles, cross sections or the bank stability toe
erosion model. However, it is the only method described here that assesses the stream
channel and the riparian buffer to determine bank stability. As such, it is more than a
bank stability assessment. According to the manual, a riparian-wetland area is function-
ing properly when there is adequate vegetation, landforms or woody debris to:
• Dissipate stream energy associated with high flows;
• Filter sediment, capture bedload and aid in floodplain development;
• Improve floodwater retention and groundwater recharge;
• Develop root masses that stabilize streambanks;
• Develop diverse channel characteristics to provide habitat; and
• Support greater biodiversity.
A Function-Based Framework » May 2012 150
-------
Chapter 8: Geomorphology, Riparian Vegetation
8. NRCS Rapid Visual Assessment Protocol
The NRCS Stream Visual Assessment Protocol (SVAP) is another rapid assessment
method that includes the riparian zone as a variable in an overall stream health evalua-
tion. This protocol can be found at www.nrcs.usda.gov/technical/ecs/aquatic/svapfnl.pdf.
The SVAP riparian zone assessment is based on the natural vegetation width, its function
as a surface flow filter and its potential for vegetative regeneration.
9. The EPA Rapid Reassessment Protocol (RBP)
The EPA Rapid Bioassessment Protocol (RBP, Barbour et al., 1999) includes riparian
areas as part of Habitat Assessment and Physicochemical Parameters (Chapter 5 of the
RBP manual). This method includes an index for rating natural vegetation buffer function
based on buffer width on each side of the stream, and based on human impacts to the
buffer function (Barton et al., 1985).
10. USFWS Stream Assessment Ranking (SAR)
The USFWS Stream Assessment Ranking (SAR) is a component of the US 301 Environ-
mental Stewardship Study, which is a green infrastructure study. The stream assessment
component consists of a CIS-based stream stability assessment method and a rapid
stream habitat and stability assessment method. It also includes restoration feasibility
protocols. The rapid assessment protocols have both office and field components. The
office component requires the use of a regional curve to determine bankfull channel
width, depth, and cross-sectional area based on the drainage area of the proposed project
site. This information is required for the field assessment portion of the protocol since
several of the assessment parameters evaluate bankfull channel conditions. The field
component of the protocol contains four sections: stream stability assessment; restoration
potential, cost and feasibility; existing riparian/instream habitat assessment; and pro-
posed riparian/instream habitat assessment. The stream stability assessment section
consists of four parts: lateral stability, vertical stability, stability trend and stream classifi-
cation. The parameters of the restoration potential, cost and feasibility include construc-
tion access, constraints, potential success/risk, and restoration potential description. The
existing and proposed riparian/instream habitat assessments consist of the same assess-
ment parameters to allow for comparison between the existing site condition and the
proposed site condition, based on the potential restoration solution. The parameters of
the riparian/instream habitat assessment include instream cover, epifaunal substrate,
velocity/depth regimes, shading, water appearance, nutrient enrichment, riparian vegeta-
tion, riparian zone, and sediment supply potential.
11. Watershed Assessment of River Stability and Sediment Supply (WARSSS)
The Rosgen (2009) Watershed Assessment of River Stability and Sediment Supply
(WARSSS) includes assessment of riparian vegetation in the Prediction Level Assessment
(PLA) Index as part of its overall channel stability analysis procedure. The existing ripar-
ian vegetation composition and density along the impacted reach is compared to the
A Function-Based Framework » May 2012 151
-------
Chapter 8: Geomorphology, Riparian Vegetation
potential vegetation that would be present along a reference reach. The riparian buffer
species composition and density are used to interpret the potential for streambank erosion
and channel instability. The assessment is a qualitative description recorded using work-
sheets (See Worksheet 14 and 15, water.epa.gov/scitech/datait/tools/warsss/pla_box07.cfm)
and should be performed by a trained biologist. There are no performance standards
developed for this assessment at this time.
Performance Standard
1. Buffer Width
There are several performance standards established for buffer width measurements.
Two standards are listed in Table 8.8. The average width performance standard for C and
E stream types is based on the literature review by Mayer et al. (2005). This research
primarily focuses on the effects of buffer width and other parameters on reducing nitro-
gen. The results showed that while some buffers with widths less than 45 feet did re-
move nitrogen, buffers that were wider than 150 feet more consistently removed nitro-
gen. The results also showed that, in general, buffers were effective as nitrogen filters
with widths between 30 and 150 feet. Buffer widths for A and B stream types can prob-
ably be narrower given that their valleys are narrower; however, the literature does not
provide recommendations on buffer widths for these stream types. The second standard
is the buffer width to meander belt width as shown in Figure 8.13. This is a new ap-
proach that is being introduced in this document for those who want to create a straight
riparian corridor with easy to manage conservation easements (if required). A minimum
meander width ratio of 3.5 is used because this is typically the minimum average value
required to yield a sinuosity of 1.2, the break between meandering and non-meandering
streams. The additional 15 feet has more to do with constructability issues for restoration
projects that include excavated floodplains. This width and the meander width ratio can
be increased if necessary to meet other project goals; however, they should not be de-
creased to meet a Functioning performance standard.
2. Buffer Density, Composition, Age, Growth and Canopy Density
Other measurement parameters, including buffer density, species composition, age-
class distribution, growth, and canopy density do not have published performance
standards established at this time. A suitable reference reach from the same region and at
the same successional stage, however, can be used to compare riparian buffer function.
Performance decisions should be made by a trained biologist or botanist with experience
in the region. For this framework, a Functioning riparian buffer would have a measure-
ment method result similar to the reference reach. A Functioning-at-Risk would have a
measurement method result that is not functioning at the level of the reference buffer, but
has existing potential for this to occur over time or with minimal additional mainte-
nance. Maintenance may include additional plantings, soil amendment or invasive species
control. Not Functioning would designate a riparian buffer that does not resemble the
reference buffer and that does not have reasonable potential to develop riparian function
A Function-Based Framework » May 2012 152
-------
Chapter 8: Geomorphology, Bed Form Diversity
over time without significant restoration efforts. These buffers may have limited estab-
lishment of intended vegetative species due to environmental conditions (drought, poor
soils, disease or flooding) occurring after planting, or they may be inundated with inva-
sive species encroaching from the surrounding landscape. A Not Functioning buffer
determined by reference reach parameters may need to be completely re-established with
more frequent maintenance to function properly.
3. Rapid Assessment Methods
The rapid assessment methods described above all have associated performance
standards with the exception of the WARSSS method. The performance standards have
been recategorized as Functioning, Functioning-at-Risk or Not Functioning. The Proper
Functioning Condition (PFC) method components for Functioning are listed above in an
order relative to how processes work to achieve a proper Functioning condition. If the
riparian-wetland is not in PFC, it is placed into one of three categories (two for this
document: Functioning-at-Risk and Not Functioning). The PFC manual uses the term
Functional-at-Risk, which is defined as being functional but with an existing soil, water
or vegetation attribute that makes them susceptible to impairment. Nonfunctional or Not
Functioning means that the riparian-wetland area clearly does not provide adequate
vegetation, landform or woody debris to dissipate stream energy associated with high
flows, and thus is not reducing erosion or improving water quality. The PFC manual adds
a third category, called Unknown, which means that the riparian-wetland manager lacks
sufficient information to make a functional determination.
The NRCS Stream Visual Assessment Protocol (SVAP)score ranges from 1 (Not Func-
tioning) to 10 (Functioning) based on natural vegetation riparian buffer width and cover-
age. The EPA Rapid Bioassessment Protocol (RBP) index values range from optimal (10) to
poor (0) based on riparian buffer widths on each side of the stream. The USFWS Stream
Assessment Ranking (SAR) scores each assessment parameter with a numerical range of 1
to 10, with 10 being the best score. Since the assessment protocol has four separate
sections, a variety of scoring combinations can be created for ranking purposes. Each of
the assessment section scores can be used individually or tallied together for ranking and
prioritization purposes.
8.7 » PARAMETER: BED FORM DIVERSITY
Description
Natural streams rarely have flat uniform beds (Knighton, 1998). Instead, the hydraulic
and sediment transport processes described above shape the stream bed into myriad forms,
depending on channel slope, type of bed material (sand, gravel, cobble, boulder, bedrock)
and other factors. These bed forms are symptomatic of local variations in the sediment
transport rate and represent vertical fluctuations in the stream bed (Knighton, 1998),
dissipating energy and creating habitat diversity. These vertical fluctuations are essentially a
form of meandering, but in the vertical direction rather than horizontal (like sinuosity).
A Function-Based Framework » May 2012 153
-------
Chapter 8: Geomorphology, Bed Form Diversity
TABLE 8.8 RIPARIAN BUFFER PERFORMANCE PARAMETERS
MEASUREMENT
METHOD
Average Buffer Width
(Ft) from Top of Bank
C and E Stream Types
Buffer Width (Ft) from
Meander Belt Width
Buffer Density (Stems/
ac)
Buffer Composition
Buffer Age
Buffer Growth
Canopy Density
Proper Functioning
Condition (PFC)
NRCS Stream Visual
Assessment Protocol
(SVAP)
EPA Rapid
Bioassessment
Protocol (RBP) Habitat
Assessment
FUNCTIONING
> 150ft
Meander belt
width at least 3.5
times the bankfull
width plus > 15
feet from outside
meander bend
Parameter is
similarto
reference reach
condition, with no
additional
maintenance
required.
Proper
Functioning
Condition
Natural vegetation
extends at least
one to two active
channel widths on
each side; or if
less than one
width, covers
entire floodplain
(8-10)
Width of riparian
zone > 18 meters
on each side;
human activities
have not impacted
zone (Optimal,
9-10)
FUNCTIONING-
AT-RISK
30 to 150ft
Meander belt width
at least 3.5 times the
bankfull width plus
10 to 15 feet from
outside meander
bend
Parameter deviates
from reference
reach condition,
limiting function;
but the potential
exists for full
functionality over
time or with
moderate additional
maintenance.
Functional-at-Risk
Natural vegetation
extends at least
one-half to one-third
active channel
widths on each side,
or filtering function
moderately
compromised (3-5)
Width of riparian
zone 12-18 meters
on each side; human
activities have
impacted zone only
minimally (Sub-
Optimal, 6-8); width
of riparian zone 6-12
meters on each side;
human activities
have impacted zone
a great deal
(Marginal, 3-5 )
NOT FUNCTIONING
<30ft
Meander belt width
< 3.5 times the
bankfull width and/
or < 10 feet from
outside meander
bend
Significantly less
functional than
reference reach
condition; little or
no potential to
improve without
significant
restoration efforts
Nonfunctional
Natural vegetation
less than a third of
the active channel
width on each side,
or lack of
regeneration, or
filtering function
severely
compromised (1)
Width of riparian
zone <6 meters on
each side; little or
no riparian
vegetation due to
human activity
(Poor, 0-2)
A Function-Based Framework » May 2012
154
-------
Chapter 8: Geomorphology, Bed Form Diversity
TABLE 8.8 RIPARIAN BUFFER PERFORMANCE PARAMETERS (CONT.)
MEASUREMENT
METHOD
USFWS Stream
Assessment Ranking
(SAR)
FUNCTIONING
All three zones of
FUNCTIONING-
AT-RISK
Only Zone 2 of
vegetation exist; vegetation is well
runoff is primarly represented; runoff
NOT FUNCTIONING
No zones of
vegetation well
represented; runoff
sheet flow; is equally sheet and is primarily
hillslopes < 10%; concentrated flow concentrated flow
hillslopes>200ft
from stream;
ponding or
(moderate gully and (extensive gully
rill erosion);
hillslopes 20-40%;
and rill erosion);
hillslopes >40%;
wetland areas and hillslopes 50-100 ft hillslopes <50 ft
litter or debris
jams are well
represented.
from stream;
ponding orwetland
from stream;
ponding orwetland
areas and litter or areas and litter or
debris jams are debris jams are not
minimally
represented.
well represented or
completely absent.
Numerous classifications of bed form exist, many of which are described in Knighton
(1998). At a broad level, bed form diversity can be grouped into three categories: sand bed
forms (ripple, dunes and antidunes), gravel/cobble bed forms (riffle, run, pool and glide)
and step-pool channels. These different bed forms are important because they provide
the environmental conditions that a variety of aquatic organisms need for survival. For
example, macroinvertebrates often colonize in riffle habitats and fish tend to stay in
pools. Without the diversity of riffles and pools, there is also a loss of diversity in macro-
invertebrates and fish. A brief description of each bed form category is described below.
Sand Bed Forms
While gravel bed streams have riffle-pool sequences, with riffles composed of gravel-
size particles, sand bed channels are characterized by median bed material sizes less than
2 mm in diameter (Bunte and Abt, 2001). Bed material features called ripples, dunes,
planebeds and antidunes characterize the sand bed form. Although sand bed streams
technically do not have riffles, the term is often used to describe the crossover reach
between pools. ("Riffle" is used in this document as an equivalent to crossover.) The size,
stage and variation of sand bed forms are created by changes in unit stream power, as
described below. These bed forms are symptomatic of local variations in the sediment
transport rate and cause minor to major variations in aggradation and degradation (Go-
mez, 1991). Sand bed forms can be divided between low-flow regimes and high-flow
regimes, with a transitional zone between the two (Figure 8.14).
Ripples occur at low flows where the unit stream power is just high enough to entrain
sand size particles. This entrainment creates small wavelets from random sediment
accumulations that are triangular in profile, with gentle upstream and steep downstream
A Function-Based Framework » May 2012
155
-------
Chapter 8: Geomorphology, Bed Form Diversity
slopes. The ripple dimensions are independent of flow depth, and their heights are less
than 0.02 meters.
As unit stream power increases, dunes eventually replace ripples. Dunes are the most
common type of sand bed form and have a larger height and wavelength than ripples.
Unlike ripples, dune height and wavelength are proportional to flow depth. The move-
ment of dunes is the major cause of variability in bedload transport rates in sand bed
streams. Dunes are eventually washed out to leave an upper-flow plane bed characterized
by intense bedload transport. This plane bed prevents the patterns of erosion and deposi-
tion required for dune development. This stage of bed form development is the transi-
tional flow regime between the low-flow features and the high-flow regime features
(Knighton, 1998).
As flow continues to increase, standing waves develop at the water surface, and the
bed develops a train of sediment waves (antidunes) that mirror the surface forms. Antid-
unes migrate upstream by way of scour on the downstream face and deposition on the
upstream face, a process that is opposite of ripples and dunes. Antidunes can also move
downstream or remain stationary for short periods (Knighton, 1998).
Gravel/Cobble Bed Forms
Meandering gravel bed streams in alluvial valleys have sequences of riffles, runs, pools
and glides that help maintain channel slope, bed stability and habitat diversity (Figure
8.15). The riffle is a bed feature composed of gravel or larger-size particles. During low-
flow periods, the water depth at a riffle is relatively shallow, and the slope is steeper than
the average slope of the channel, so water moves faster over riffles. Riffles control the
stream bed elevation and are usually found between meander bends. Runs are a transi-
tional bed form between the riffle and the pool. The pool is located along the outside of a
meander bend and is much deeper than the riffle. The slope of the pool is also much
flatter than the riffle. Pools can also be found in riffle settings if scour is created by a flow
obstruction, like a boulder or large woody debris, further improving the overall diversity.
The inside of the meander bend is a depositional feature called a point bar. A glide is the
transitional bed form between the pool and the next riffle and is the only bed form that
slopes uphill (i.e., if a person was walking through the pool in a downstream direction,
he/she would have to walk uphill to reach the next riffle). The glide serves as a spawning
area for many species of fish because oxygen is forced up through the sediments, as the
water from the deep pool is forced up through the gravel to reach the riffle.
As stage increases, water and sediment transport character changes as they travel over
riffles and through pools. At low flows, pools are depositional features, and riffles are
scour features. At high flows, the water surface becomes more uniform, i.e., the water
surface slope increases at a faster rate over the pools than the riffles. The pools, therefore,
have a slope that is similar to the riffle but a much greater depth. This means that the
shear stress is greater in the pool than the riffle. With a relative increase in shear stress,
pools scour; a decrease in shear stress occurs over the riffle during the falling limb of the
hydrograph, causing bed material deposits (Knighton,
A Function-Based Framework » May 2012 156
-------
Chapter 8: Geomorphology, Bed Form Diversity
FIGURE 8.14 SAND BED FORMS (after Knighton, 1998)
10--
5--
cc
O
LLJ
H 0.5 --
C/5
0.1 --
0.05--
Antidunes and
Plane Bed
Transition
I
Dunes
Ripples
Plane Bed
(Limited or No Sediment Movement)
J I
I
I I I I
0.2 0.4 0.6 0.8
MEDIAN FALL DIAMETER (mm)
1.0
Source: Adapted from Knighton (1998)
Step-Pool Channels
A step-pool bed profile is characteristic of steep streams formed within colluvial
valleys, with valley slopes typically greater than 2% or 3% (Wohl, 2000). Steep moun-
tain streams demonstrate step-pool morphology as a result of episodic sediment transport
mechanisms. Because of the high energy associated with the steep channel slope, the
substrate in step-pool streams contains significantly larger particles than streams in
A Function-Based Framework » May 2012
157
-------
Chapter 8: Geomorphology, Bed Form Diversity
flatter alluvial valleys. Steps form from accumulations of boulders and cobbles that span
the channel, resulting in a backwater pool upstream and a plunge pool downstream.
Smaller particles collect in the interstices of steps, creating stable, interlocking structures
(Knighton, 1998). An example is shown in Figure 8.15.
In contrast to meandering streams that dissipate energy through meander bends,
step-pool streams dissipate energy through drops and turbulence. Step-pool streams have
relatively low sinuosity, and pattern variations commonly result from debris jams, topo-
graphic features and bedrock outcrops.
FIGURE 8.15 TYPICAL RIFFLE-POOL AND STEP-POOL PROFILES
TYPICAL RIFFLE-POOL
CHANNEL PROFILE
HIGH WATER SURFACE
RIFFLE
POOL
TYPICAL STEP-POOL
CHANNEL PROFILE
STEP
STEP
POOL
Source: Adapted from Knighton (1998)
A Function-Based Framework » May 2012
158
-------
Chapter 8: Geomorphology, Bed Form Diversity
Measurement Method
Bed form diversity is relatively simple to assess. A longitudinal profile of a stream
channel provides detailed information about the bed form and can be used to quantify
diversity (Harrelson et al.; 1994). Parameters that quantify bed form diversity include:
percent riffle and pool, facet slope, pool-to-pool spacing and depth variability. A descrip-
tion of each parameter is provided below.
1. Percent Riffle and Pool
This parameter measures the percentage of riffles and pools for a stream reach. Runs
and glides, although important habitat features, are included under the riffle and pool
percentage, respectively. The percentages can be determined by comparing the thalweg
profile to the water-surface profile, and measuring the length of the feature from the
stationing. This approach requires a moderate level of effort and complexity because a
profile must be surveyed to collect the data. A rapid approach can be used where the
feature lengths are simply measured using a tape, rather than taken from the profile
(Appendix Ac). The facet length (riffle or pool) is then divided by the total reach length to
calculate the percentage.
Riffles are identified on the profile as the sections of channel that are steeper than the
average channel slope. The water surface over the riffle should also be steeper than the average
slope. Beware of channel blockages, such as beaver dams, that create flat water-surface
slopes (backwater) over previously established riffles. An example is shown at station 760
on the profile in Figure 8.16. The upstream riffles have been "drowned out" to station 550
and are now classified as a pool.
After the riffles and pools have been identified on the longitudinal profile, they can be
plotted on the plan view as shown of Figure 8.17. The location of the riffles and pools can
now be compared with the meander geometry. Ideally for C and E stream types, the
pools will be located at meander bends, and the riffles will be between meander bends.
Figure 8.17 shows a riffle at station 2+00, which is the outside of an eroding meander bend.
The erosion is partly caused by the steep slope and, therefore, high shear stress associated
with the riffle. Pools that are located in meander bends help dissipate energy by having a
lower slope, among other things, such as a greater cross-sectional area and depth.
Figures 8.16 and 8.17 show that overall the stream reach has 43% riffle and 57% pool
bed forms. Rosgen C and E reference reach streams in the Southeastern US generally have
riffle-pool percentages from 60:40 to 80:20, so more riffle bed form than pool. In this
example, the bed form is predominately pool because of the beaver dam. The riffles that
are present are in unstable locations (meander bend) or very short; the longest riffle is
near the end of the reach. The determination of whether a bed form was a riffle or pool
was made from an analysis of the bed and water-surface profile (Figure 8.17).
2. Facet Slope
Facet or feature slopes help to identify riffles and pools as described above. In addition,
facet slopes can be used to measure the quality and stability of the bed form, e.g., steep
A Function-Based Framework » May 2012 159
-------
Chapter 8: Geomorphology, Bed Form Diversity
FIGURE 8.16 EXISTING (PRE-RESTORATION) LONGITUDINAL PROFILE SHOWING THALWEG,
WATER SURFACE, BANKFULL STAGE, LEFTTOP OF BANK(LTOB) AND RIGHTTOP OF BANK(RTOB)
Tnalweg
Water Surface
LTOB
RTOB
Bankfull
0 100 200 300 400 500 600 700
Station (Feet)
Source: Adapted from original graph by Michael Baker Corporation
800 900 1000 1100 1200
FIGURE 8.17 PLAN VIEW MAP SHOWING RIFFLES IN BROWN AND POOLS IN BLUE
STEEP HILLSLOPE
0 50 00 50
FLOW
THALWEG
EDGE OF CHANNEL
RIFFLE
STREAM CROSSING
ROAD I I POOL
Source: Adapted from original graph by Michael Baker Corporation
A Function-Based Framework » May 2012
160
-------
Chapter 8: Geomorphology, Bed Form Diversity
riffles are often comprised of coarser bed material because the finer sediments are transported
downstream. However, if the riffle gets too steep, larger particles will be transported and
the riffle could degrade. Riffle slope stability can be assessed with competency equations
by comparing the riffle slope ratio to reference reach ratios. The riffle slope ratio is the
riffle slope divided by the average channel slope (Rosgen, 2009). Pool slopes are also
important descriptors of quality and stability and should be much flatter than the overall
water surface slope to minimize erosional forces acting on the outside bank. However, if
the pool slope is zero, the pool does tend to fill and stagnate at low-flow stages.
3. Pool-to-Pool Spacing
Pool-to-pool spacing measures the frequency of pools in the stream reach and is the
distance measured along the stream centerline or thalweg, between the deepest point of
two pools. It is most often measured from the longitudinal profile; however, it can be
estimated rapidly by simply using a tape. A rapid approach may be used by regulatory
agencies to estimate the pool-to-pool spacing of a restored reach. The value is often
converted into a dimensionless ratio by dividing the result by the bankfull riffle width.
Dimensionless ratios can then be compared to known reference reach ratios of the same
channel type to determine if the spacing is within the normal range.
For C and E stream types, stability problems often occur when the pool-to-pool spac-
ing becomes too low. Monitoring studies in North Carolina showed that severe bank
erosion occurred when the pool-to-pool spacing ratio was less than 3.0 to 3.5. In these
cases, erosion was observed from the outside meander bend to the downstream point
bar. For streams in colluvial valleys (B stream type), it is the opposite. Generally, closer
pool-to-pool spacing leads to more stable and diverse bed forms. Pool-to-pool spacing
ratios greater than 5 often have minor to major headcut problems, especially in areas
where the channel was reconstructed (Harman and Starr, 2008). (See Figure 8.18.)
4. Depth Variability
Depth variability can be assessed by measuring the bankfull pool depth at each pool
along the stream reach, and then dividing these depths by a representative mean riffle
bankfull depth. For this assessment, the pool depths can be measured from the longitudi-
nal profile. The bankfull riffle mean depth can be measured at a representative riffle cross
section. The mean depth is then calculated as the cross-sectional area divided by the
bankfull width. This dimensionless ratio is referred to as the Pool Max Depth Ratio
(Rosgen, 2009). When looking at a stream reach, the variability between Pool Max Depth
Ratios provides information on how the stream is processing sediment. If all the ratios
are near the same value, it indicates that the pools are all the same depth and are likely
filling with sediment. However, this does vary by geologic setting and stream type. It is
most desirable to have a range of Pool Max Depth ratios, as it indicates a wide variety of
pool depths and high pool habitat diversity.
A Function-Based Framework » May 2012 161
-------
Chapter 8: Geomorphology, Bed Form Diversity
FIGURE 8.18 TYPICAL POOL-TO-POOL SPACING MEASUREMENTS
GLIDE R|FFLE
POOL TO POOL SPACING (P-P)
POOL TO POOL SPACING RATIO = pool to pool spacing (P-P)/bankfull riffle width
Source: Reproduced with permission from Michael Baker Corporation
Performance Standard
Performance standards for determining whether a stream is Functioning from a bed
form diversity standpoint should be considered with stream channel type and expected
habitat diversity in mind. In general, it is good to compare what is observed in the field
with what is known about stable, reference reach channel conditions.
1. Percent Riffle and Pool
Reference reach streams in alluvial valleys, like C and E stream types, typically have
more riffles than pools. It is generally agreed that having more riffles than pools is one
important factor to support healthy fish populations; however, it is difficult to find litera-
ture that provides guidance on ideal percentages for riffles and pools. In NC, projects that
had 60-70% riffle and 30-40% pool seemed to be preferred over streams that were riffle
or pool dominated. As the percentage increased to 70-80% riffle, the quality of fish
habitat was diminished due to a lack of pool habitat. Streams with greater than 80%
riffle often resemble the bed form of a channelized stream.
A stream reach dominated by pool bed forms in C and E stream types also lacks the
necessary diversity for varied aquatic species, especially macroinvertebrates. If 60-70% of
the reach is riffle (Functioning), then 30-40% of the reach should be pool. As the percent-
age of pools increase, bed form diversity goes down (Table 8.9). Once the reach exceeds
50% it is unlikely that the bed form diversity is comparable to high-quality C and E
A Function-Based Framework » May 2012
162
-------
Chapter 8: Geomorphology, Bed Form Diversity
reference reach streams. This can be a problem in older stream restoration projects where
cross vanes were installed at the head of the riffle. The intent was to keep the upstream
pool slope fairly flat, which it does. However, the cross vane also creates a pool down-
stream of the structure, which in this case is the riffle. The result is that a scour pool
replaces part of the riffle length, and depending on the meander geometry, this can create
too much pool length and not enough riffle length. There is very little data in the litera-
ture to provide riffle and pool length percentages for B type channels. However, there is
information on pool-to-pool spacing and substrate quality, so performance standards are
discussed in the following sections.
The percent riffle and pool is the most subjective measurement method provided in
this document. If this method is used as a performance method, it should be used in
conjunction with another method that better defines bed form complexity, like LWD
measurement methods, pool-to-pool spacing ratios or slope ratios.
2. Pool-to-Pool Spacing Ratios
The performance measures for pool-to-pool spacing are shown below in Table 8.9.
Separate ratios are shown for watershed drainage areas below and above 10 square miles.
Results from past projects show that severe bank erosion occurs when the pool-to-pool
spacing ratio is less than 3.0. This problem is related to the MWR problem (discussed
under lateral stability) and often occurs when practitioners force a meandering stream
into a confined setting. This problem may also show up in the percent riffle-pool mea-
sure, e.g., there may be more pool length than riffle length. Projects in drainage areas
below 10 square miles tend to be more stable and have better bed form diversity if the
pool-to-pool spacing ratio is between 3.5 and 5.0. However, for larger streams, the ratio
increases to between 5.0 and 7.0 (Langbein and Leopold, 1966; Gregory et al., 1994). But
as the ratio decreases, the same problem can exist in these larger streams.
The spacing of pools is inversely related to slope, i.e., as slope increases, pool-to-pool
spacing decreases. Whittaker (1987) and Chin (1989) report an average pool-to-pool
spacing of 2 to 3 times the channel width for stream slopes between 3% and 5 %. Grant
et al. (1990) reported pool-to-pool spacing of 2 to 4 times the channel width for two
Oregon streams. These ranges can be more variable based on the presence of bedrock
outcrops and large boulders. The Functioning category shown in Table 8.9 uses a value of
less than 4, which is the higher end of the range between these two studies. A minimum
number was not provided because a lower spacing typically does not lead to stability
problems or a decrease in functionality. As the spacing increases in these moderately
steep channels, the risk of bed instability increases and functionality decreases.
3. Depth Variability
Depth variability is assessed by measuring the Pool Max Depth Ratio. Performance
measures are shown below for gravel bed C and E streams (C4 and E4) and gravel bed B
streams (B4). When the ratio is above 1.5 for B4, C4 and E4 stream types, the pools are
typically well formed and Functioning. This ratio is less variable in gravel and cobble bed
A Function-Based Framework » May 2012 163
-------
ChapterS: Geomorphology, Bed Material Characterization
These ratios are based on
reference reach streams in
NC and may need to be
adjusted based on local
reference reach conditions.
streams than streams with sand beds. Pool
depth in sand bed channels (C5 and E5)
fluctuate more because the sand is mobilized
from the riffle (crossover) sections during
lower flows. As a result, the pools may fill in
more during low-flow periods and scour
during bankfull events. A ratio of 1.2 is used
to indicate a Functioning C5 or E5 stream type. Like the C4 and E4 stream types, as the
ratio decreases, bed form diversity decreases. These ratios are based on reference reach
streams in NC and may need to be adjusted based on local reference reach conditions.
TABLE 8.9 BED FORM DIVERSITY PERFORMANCE PARAMETERS
MEASUREMENT METHOD I FUNCTIONING I FUNCTIONING-AT- I NOT FUNCTIONING
| | RISK
Perennial Streams in Alluvial Valleys (C, E)
Percent Riffle
Pool-to-Pool Spacing Ratio
(Watersheds < 10 mi2)
Pool-to-Pool Spacing Ratio
(Watersheds > 10 mi2)
Depth Variability - Gravel
Bed Streams (Pool Max
Depth Ratio)
Depth Variability - Sand
Bed Streams (Pool Max
Depth Ratio)
60 to 70
4 to 5
5-7
> 1.5
> 1.2
70 to 80
40 to 60
3 to 4 and 5 to 7
3. 5-5.0 and 7
to 8
1.2 to 1.5
1.1 to 1.2
>80
<40
< 3 and > 7
< 3. 5 and >8
< 1.2
< 1.1
Moderate Gradient Perennial Streams in Colluvial Valleys
Pool-to-Pool Spacing Ratio
(Slope between 3 and 5%)
Depth Variability (Pool Max
Depth Ratio)
0.5 to 4
> 1.5
4 to 6
1.2 to 1.5
>6
< 1.2
8.8 » PARAMETER: BED MATERIAL CHARACTERIZATION
Description
Bed material (substrate) characterization is an important parameter in function-based
assessments and stream restoration designs in gravel bed streams. The composition of the
stream bed influences the character of the bed forms, sediment transport, macroinverte-
brate habitat and fish habitat (Harrelson et al., 1994). The influence of substrate on chan-
A Function-Based Framework » May 2012
164
-------
ChapterS: Geomorphology, Bed Material Characterization
nel form and process varies by stream type. For example, large boulders and cobbles
create step-pool bed morphology in steep gradient A and B stream types. Gravel bed
material creates riffle-pool sequences in lower gradient C and E stream types, and sand
bed material creates ripples and dunes in low gradient C, E and DA stream types.
Characterizing the bed material for the purpose of showing functional lift associated
with a stream restoration project is most appropriate in gravel bed streams. The goal for
these projects is to show that the bed coarsens after restoration; this implies that the
stream bed has excessive fine-grained sediments (sand) prior to restoration, which is
typically caused by streambank erosion. Restoration techniques are used to minimize
streambank erosion and thereby decrease the supply of the fine-grained sediments. Other
restoration techniques, like reconnecting the stream to the floodplain and creating the
appropriate geometry, can improve sediment transport processes, which may transport
the finer-grained material out of the project reach.
An example of this type of project is shown below in Figure 8.19. Prior to restoration,
the project reach was channelized and had eroding streambanks that were comprised
mostly of sand. Streambanks were also eroding upstream of the project reach. The
restoration project created a meandering C/E stream type with a bank height ratio of 1.0
(well connected to the floodplain). The photo was taken during the first year after con-
struction and soon after a winter flood event. Sandy material from upstream bank erosion
deposited on the point bar and floodplain; however, the riffle remained coarse and the
pool maintained a depth that was much deeper than the riffle.
FIGURE 8.19 SOUTH FORK MITCHELL RIVER, KRAFT STREAM RESTORATION PROJECT
Source: Reproduced with permission from Michael Baker Corporation
A Function-Based Framework » May 2012
165
-------
ChapterS: Geomorphology, Bed Material Characterization
The bed material was characterized before restoration and for five years after restoration.
Figure 8.20 shows the grain size distributions prior to restoration and for five years
post-restoration. The x-axis is the size class of the bed material samples in millimeters,
and the y-axis is the cumulative percent. The median particle size is where 50 on the
y-axis intercepts the line. This value is called the D50, meaning that half of the values are
larger and half are smaller than this value. The D84 means that 84% of the values are
smaller than this value. Figure 8.20 shows that in general, the bed material coarsened
after restoration when compared to the 2002 pre-restoration curve. The suite of curves
also shows that there was more variability in the finer-grained sediments (less than the
D50) than there was in the coarser grained sediments (greater than the D50). This is
common because smaller particles are much more mobile than large particles. The curves
also show periodic coarsening and fining during the monitoring years. This is shown
more clearly in Figure 8.21.
FIGURE 8.20 BED MATERIAL CHARACTERIZATION OFTHE KRAFT STREAM
RESTORATION PROJECT 2002-2007
100
0.01
1 10 100
Bed Material Size (mm)
• Kraft 2003
• Kraft 2004
• Kraft 2005
• Kraft 2006
•Kraft 2007
—-2002B/4
Pre-Resto ration
Source: Adapted from original graph by Michael Baker Corporation
Figure 8.21 shows how the D16, D35, D50 and D84 change from the pre-restoration
condition in 2002 through the last year of monitoring in 2007. The D16, which is a fine
sand, changes very little between the monitoring years. This is due to the large amount
of sand that is in the channel from upstream bank erosion. This material is easily trans-
ported and is mobilized in most storm events. The D35, D50 and D84 all coarsen after
restoration with the D35 and D50 changing from sand-size to gravel-size particles.
Interestingly, the dip in 2005 occurred during the same year as the remnants from hurri-
cane Francis moved through the area, causing the largest flood of the monitoring period.
The bed did shift towards finer-grained sediments that year, but still remained coarser
than the pre-restoration condition. The bed material then rebounded in 2006 and was the
coarsest of the monitoring period in 2007.
A Function-Based Framework » May 2012
166
-------
ChapterS: Geomorphology, Bed Material Characterization
FIGURE 8.21 BED MATERIAL CHARACTERIZATION OF D16, D35, D50 AND D84 PRIOR TO
RESTORATION AND FOR FIVE YEARS POST-RESTORATION
90.0
800
700
600
500
400
300
Post-Restoration
S
VI
{£.
3003
2004
JLClb
2007
h vflbMrirri I
cCSlrnm)
Source: Adapted from original graph by Michael Baker Corporation
The point of showing these graphs is to illustrate that under the correct conditions,
stream restoration projects can show an improvement (coarsening) due to restoration
activities, even if the upstream watershed is not pristine. The best cases for showing
improvement are stream reaches that have gravel and cobble in the bed material, but
with sandy material being supplied by bank erosion. Projects that are the least likely to
show improvement are sand bed streams that do not have gravel and/or cobble sources
of bed material.
Measurement Method
The most common method for measuring bed material or substrate is the Wolman
(1954) pebble count procedure. The two measurement methods described below use the
pebble count method for sampling the bed material. Based on project goals, however,
there are many ways that the pebble count procedure can be implemented. Bunte and Abt
(2001) provide a comprehensive manual on sampling and analyzing surface and subsur-
face particles. This manual is available online at www.stream.fs.fed.us/publications/docu-
mentsStream.html. The level of effort for these two methods is moderate if the values are
compared to existing reference reach data sets and can become intensive if the reference
data sets need to be developed (Appendix Ac).
1. Size Class Pebble Count Analyzer
Potyondy and Bunte (2007) and Bevenger and King (1995) provide spreadsheet tools
and instructions for managing pebble count data. These spreadsheets are useful for
stream restoration monitoring projects because they can be used to compare a project
reach to a reference reach/watershed. The spreadsheet includes statistical applications
A Function-Based Framework » May 2012
167
-------
ChapterS: Geomorphology, Bed Material Characterization
that can be used to determine if select sediment size classes from the project reach are
statistically different than the reference reach. (Spreadsheets are available at www.stream.
fs.fed.us/publications/software.html.)
2. Riffle Stability Index (RSI)
Kappesser (2002) developed a Riffle Stability Index (RSI) to estimate the degree of
increased sediment supply to riffles in streams with gradients between 2% and 4%.
Kappesser states that the RSI can be used where sediment supply from headwater activi-
ties is depositing materials on riffles and filling pools, and reflects qualitative differences
between reference watersheds and managed watersheds.
Performance Standard
Performance parameters for substrate distributions are shown below in Table 8.10. The
Size Class Pebble Count Analyzer developed by Potyondy and Bunte (2007) and Bevenger
and King (2005) can be used in low- and high-gradient channels. Using this method, a
Functioning stream is defined as one where select bed material classes are not statistically
different than the reference reach or watershed. A Not Functioning stream is where the
project stream is statistically finer than the reference reach/watershed. One issue with
this method is that there is no guidance or data to suggest an appropriate range for
Functioning-at-Risk, so this would need to be determined by the user.
The RSI is recommended for B3 and F3b channels because the method provides scores
for Functioning, Functioning-at-Risk and Not Functioning (although the terminology
differs). Kappesser (2002) stated that riffles from Idaho and Virginia scoring less than 70
were indicative of watersheds in good condition (Functioning). Values between 70 and 85
indicated watersheds in fair condition (Functioning-at-Risk), and values greater than 85
indicated poor conditions (Not Functioning).
TABLE 8.10 BED MATERIAL CHARACTERIZATION PERFORMANCE PARAMETERS
MEASUREMENT METHOD
Size Class Pebble Count
Analyzer
Riffle Stability Index (RSI)
for Rosgen B3 and F3b
FUNCTIONING
Project Reach is
not statistically
different than
reference reach
<70
FUNCTIONING-
AT-RISK
N/A
70 to 85
NOT FUNCTIONING
Project Reach is
statistically different
(finer) than
reference reach
>85
A Function-Based Framework » May 2012
168
-------
Chapter 9
Physicochemical
The Physicochemical functions of a stream are determining factors of aquatic ecosys-
tem health. Many lotic organisms are affected by even small changes in water chemistry
and habitat. Physicochemical functions include the interaction of physical and chemical
processes to create the basic water quality of the stream (including temperature, dissolved
oxygen, conductivity, pH and turbidity), as well as to facilitate nutrient and organic
carbon processes. The parameters used to describe Physicochemical functions are includ-
ed in Level 4 of the Pyramid. These parameters provide both direct and indirect indica-
tions of stream condition and its ability to support biological communities (Level 5).
Understanding what is expected for these parameters in a project stream, based on the
reference condition and what the stream actually demonstrates, will provide a compre-
hensive Physicochemical stream assessment. Determination of the reference condition
using data from reference streams that support desired biological communities is important.
Before beginning an assessment, a review of Total Maximum Daily Load (TMDL) values
determined based on water quality standards, as well as review of specific watershed
plans, can determine what Physicochemical constituents are of concern for the stream.
These resources can identify what is being measured and what approaches are currently
being applied to monitor Physicochemical parameters and to improve water quality.
Measurement of Physicochemical functions also requires an understanding of what
influential variables are present that cannot be affected by restoration at the reach scale.
These variables include external discharges from upstream, point source and non-point
source contributions, and the effects of land-use changes in the watershed. These vari-
ables highlight the need for preliminary considerations of site selection and reach length
if the goal is to improve stream Physicochemical function. Climate factors will also have
a significant effect on Physicochemical functions, but these environmental variables
cannot be controlled at any scale. Some of these variables that are beyond the scope of
the restoration plan can be differentiated from variables that are controllable through
comparisons with upstream, downstream and reference stream conditions. The ability to
evaluate the actual effects of stream restoration within a reach with statistical confidence
should be considered by performance standards.
Table 9.1 provides a list of the Physicochemical parameters included in this chapter,
along with their associated measurement methods and availability of performance
standards. Although there are many additional parameters that can determine Physico-
chemical function, e.g., alkalinity, pollutants and metals; however, those included in this
chapter are considered the most common and the most important parameters for assess-
ment and restoration. Appendix Ac includes a list of all the example Physicochemical
A Function-Based Framework » May 2012
169
-------
Chapter 9: Physicochemical, Water Quality
measurement methods along with information about the method's type, level of effort,
level of complexity, and whether it is a direct or indirect measure of the function-based
parameter. The criteria used to make these determinations are provided in Chapter 4.
TABLE 9.1 PHYSICOCHEMICAL PARAMETERS, MEASUREMENT METHODS AND
AVAILABILITY OF PERFORMANCE STANDARDS
PARAMETER
Water Quality
Nutrients
Organic Carbon
MEASUREMENT METHOD
1. Temperature
2. Dissolved Oxygen
3. Conductivity
4. pH
5. Turbidity
1. Field test kits using reagents
reactions
2. Laboratory analysis
1. Laboratory analysis
PERFORMANCE
STANDARD
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
9.1 » PARAMETER: WATER QUALITY
Description
Temperature
Temperature is a physical property that indicates the relative hotness or coldness of
water. Stream temperature can influence several other Physicochemical parameters
directly, including dissolved oxygen (DO) concentrations, conductivity and pH (USGS,
2010). As temperature increases, DO held in the water column is reduced based on
changes in solubility of gases with temperature. Warm water holds less DO than cold
water (Mortimer, 1981). As temperature increases, conductivity increases as more mol-
ecules become dissolved and release ions into solution. These ions can also have an effect
on pH, which is a measure of hydrogen and hydroxide ions in the water column (Stumm
and Morgan, 1996). Biological functions within streams are also affected by temperature,
which regulates lifecycles, spatial distribution and metabolism of all trophic levels.
Temperature cues control the lifecycles of most stream organisms, signaling activities
such as reproduction by microbial communities, emergence by macroinvertebrates, and
spawning by fish (Hynes 1970). Stream temperature can be highly variable within a short
distance between microhabitats, such as temperature differences between warmer back-
water depositional areas and the main channel (Hauer and Hill, 2006). Warmer stream
temperatures increase the rate of metabolic processes, such as photosynthesis and respira-
tion, while most aquatic organisms reduce their metabolic processes during colder
months (Hynes, 1970). Fishery managers have long recognized the importance of tem-
perature to fish distribution and have separated lotic systems into warm-water streams
A Function-Based Framework » May 2012
170
-------
Chapter 9: Physicochemical, Water Quality
and cold-water streams to describe habitat (Moyle and Cech, 1982).
Stream temperatures are influenced by climate, streamflow and depth, sunlight expo-
sure and the riparian canopy. Air temperature above the water surface affects stream
temperature through heat transfer. Daily and seasonal stream temperatures fluctuate
with air temperatures over the same time period, although the stream has less fluctuation
due to the higher latent heat of water (Hauer and Hill, 2006). Precipitation and watershed
runoff influence stream temperatures when there is a great enough temperature differ-
ence between watershed runoff and streamflow, and when there is a large enough volume
of runoff entering streamflow. The same effect occurs with point-source discharges from
power plants and industrial processes, and with hyporheic groundwater inputs through
the streambed and banks (USEPA, 1997b).
Groundwater tends to be cooler than ambient water temperatures in summer months
and warmer in winter months, due to the influences of soil temperature (Smith, 2005).
Streamflow can affect temperature through turbulence, mixing surface and subsurface
waters for a more even temperature distribution in running water compared to stagnant
water. Shallow flow depth in small streams has less variation compared to deeper, larger
streams where a temperature gradient can occur between surface and subsurface water
(Hynes, 1970). Temperature generally decreases as depth increases due to less sunlight
and atmospheric influence (Wetzel, 2001). Exceptions do occur, however, such as when
surface water temperatures drop below freezing and act as an insulating layer that keeps
deeper waters warm (Hynes, 1970). Sunlight can be the most influential factor for stream
temperature, particularly in open waters (Hauer and Hill, 2006). Effects of sunlight are
primarily dependent on the presence and relative density of a riparian canopy. A dense,
tall canopy will filter more sunlight, diminishing the rise in temperature caused by solar
radiation and reducing variability in stream temperatures over time (Allan and Castillo,
2007). Exposure to sunlight is also dependent on geographic latitude and variations
throughout the day and the seasons.
Stream temperatures that are significantly different from ambient temperatures mea-
sured within reference streams should be regulated to maintain healthy biological com-
munities. Even though temperatures of external flow contributions from watershed
runoff and point-source discharges generally cannot be controlled, they should be consid-
ered to determine their impact and potential incorporation into a restoration plan. Stream
restoration techniques can help regulate temperatures by providing adequate baseflow
and flow duration (Level 1), since flowing water is well mixed with less temperature
fluctuation. There are several methods that can be used to improve groundwater ex-
change through the hyporheic zone and streambanks to help regulate temperatures.
Floodplain connectivity described in Level 2 will slowly recharge groundwater for a more
consistent discharge through the hyporheic zone (Winter et al., 1998). Lateral stream
stability, the riparian buffer and the degree of bed form diversity are all Level 3 param-
eters that can be used to regulate temperature. Creating a stable channel that carries its
sediment and water effectively will help maintain consistent baseflow. Riparian buffers
and large woody debris (LWD) within the channel can maintain consistent and generally
A Function-Based Framework » May 2012 171
-------
Chapter 9: Physicochemical, Water Quality
cooler temperatures over time by providing shade (Figure 9.1). Changes to the stream
channel that improve bed form diversity, including deep pools, will help regulate tem-
peratures in various biological habitats.
Ambient water temperatures with less fluctuation occur in lotic systems when the follow-
ing conditions are present:
• Minimal variability between watershed runoff temperatures and stream temperatures;
• Adequate baseflow to provide mixing to prevent stagnant water;
• Floodplain connectivity to support hyporheic groundwater recharge for more consis-
tent temperatures;
• Established riparian buffer to provide shade to help keep the water cool on hot sunny
days and provide thermal regulation with less fluctuation over time; and
• Bed form diversity, as deep pools offer cooler waters for fish habitat, cover features (such
as logs, rocks and undercut streambanks) and provide shade for cooler temperatures.
FIGURE 9.1 OVERHANGING VEGETATION PROVIDES SHADE IN NEWLY RESTORED STREAMS
Figure 9Aa Restoration site immediately after
construction.
Figure 9Ab Same restoration site seven years after
construction with overhanging vegetation that
provides shade and reduces temperature variation.
Source: Reproduced with permission from Michael Baker Corporation
Dissolved Oxygen
Oxygen dissolved in the water column is required by stream biota to sustain life. The
amount of dissolved oxygen (DO) significantly affects biological respiration rates, as well
as the solubility of other chemical constituents like inorganic nutrients. In lotic systems,
these effects become important in the substrate hyporheic zone where exchange of DO
from surface waters to subsurface waters maintains microbial communities and provides
habitat for stream biota (Wetzel, 2001).
Oxygen enters the water column primarily through diffusion from the atmosphere.
Streamflow creates turbulence, which leads to additional entrainment of oxygen from the
atmosphere (USEPA, 1997b). Turbulence is increased by rough channel beds (Hynes,
A Function-Based Framework » May 2012
172
-------
Chapter 9: Physicochemical, Water Quality
1970) and structures, such as rocks and large woody debris that rise above the water
surface, creating eddies and mixing (Gordon et al., 2004). The water column is considered
saturated when DO concentrations are in equilibrium with oxygen in the atmosphere.
The amount of DO is also influenced by temperature, altitude and salinity. DO is more
soluble in colder water than warmer water. In larger rivers, temperature may play a
greater role than diffusion in influencing DO levels, due to smaller surface area relative to
volume and less turbulence. Small streams with turbulent flow, however, can maintain
DO concentrations near saturation, regardless of daily and seasonal temperature changes
(Allan and Castillo, 2007). Streams at higher altitudes generally have higher DO concen-
trations than those at lower elevations due to differences in atmospheric pressure (USE-
PA, 1997b); and DO concentrations decline as salinity increases (Wetzel, 2001).
Oxygen is both produced and consumed within the lotic system through biological
and chemical processes. Primary producers such as phytoplankton, algae and aquatic
plants (macrophytes) release oxygen during photosynthesis, a process that produces
organic material using inorganic carbon (CO2) and energy from sunlight. Aquatic organ-
isms, from microbes to fish, consume oxygen during the process of respiration when they
metabolize the organic materials. In larger, slow-moving rivers with ample sunlight
exposure, photo synthetic activity can be high enough to elevate DO levels during day
while subsiding overnight. Without these biological processes, the effects of daily tem-
perature changes and reduced diffusion rates would cause the opposite trend in rivers
(Allan and Castillo, 2007). Dissolved oxygen concentrations can also be affected by
availability of dissolved organic matter, whether through direct chemical reactions or
through indirect stimulation of microbial respiration (Wetzel, 2001).
In natural streams, there is a balance between the rate of oxygen supply from diffu-
sion, entrainment and photosynthesis, and the rate of oxygen consumption through
biological metabolism and abiotic chemical reactions (Wetzel, 2001). This balance en-
sures that oxygen production is greater than consumption, and sufficient oxygen is
available to support life at all trophic levels. Pollutants, such as excess nutrients and
organic waste contributed from surface runoff and point-source discharges, can alter this
balance and create conditions where more oxygen is consumed. One popular example is
the algal bloom (when algal production increases as a result of excess nutrient loading), also
referred to as eutrophication. Even though algal photosynthesis produces oxygen, micro-
bial respiration rates increase DO consumption to a greater extent during decomposition
of the algal biomass and its waste products (Carpenter et al., 1998). Drastic oxygen
depletion may occur, causing anaerobic conditions within the water column that harm
other organisms, e.g., fish kills (Hynes, 1960).
DO concentrations in impaired streams can be improved through removing sources of
excess nutrients and organic pollutants in watershed discharges that influence stream-
flow. On a reach scale, stream restoration techniques can improve DO concentrations
using channel modifications that enhance flow dynamics described in Level 2. Narrowing
a channel that has been over-widened and increasing channel slope can maintain base-
flows for better oxygen diffusion rates. Removal of stream impoundments, such as dams,
A Function-Based Framework » May 2012 173
-------
Chapter 9: Physicochemical, Water Quality
will restore flowing water and prevent the increase in temperature that occurs behind the
obstruction. In-stream structures used to improve Geomorphology function can increase
streamflow turbulence, including boulder clusters and cross vanes (Fischenich and Seal,
1999). (See Figure 9.2.) Riparian buffer establishment will indirectly improve DO concen-
trations by reducing stream temperature through shading.
Higher concentrations of DO occur in stream systems when the following conditions
are present:
• Excess nutrient and organic pollutant loads are controlled, maintaining a balanced
biological system in which respiration does not consume more dissolved oxygen than
is produced;
• Flowing water, which contains more oxygen than stagnant water through entrain-
ment and mixing;
• In-stream structures, breaking the water surface to create turbulence and mixing; and
• Established riparian buffer, which provides shade for cooler water temperatures to
increase the solubility of oxygen in the water column.
FIGURE 9.2 FLOWTURBULENCE CREATED FROM ROCK CROSS VANE STRUCTURE
Source: Reproduced with permission from Michael Baker Corporation
Conductivity
Conductivity is the measure of water's ability to conduct electrical current through
dissolved ions. Inorganic compounds are good conductors, while organic compounds are
poor conductors. This makes conductivity a good estimate of the total inorganic dissolved
solids present in the water column (Eaton et al., 2005). Some of the more common inor-
ganic dissolved ions include anions such as chloride, nitrate, sulfate and phosphate, and
cations such as sodium, magnesium, calcium, potassium and aluminum. Conductivity is
A Function-Based Framework » May 2012
174
-------
Chapter 9: Physicochemical, Water Quality
primarily used as a baseline chemical indicator of stream health and is a good screening
tool for stream restoration projects. Conductivity can be used to measure changes in
discharge characteristics, external flow contributions, pollutant load and other factors
affecting the chemical composition of streamflow (USEPA, 1997b).
The amount of conductivity depends to a greater extent on the concentration of
charged ions rather than the types of ions present. This characteristic makes it a good
measure of total dissolved solids across aquatic resources (Allan and Castillo, 2007).
Conductivity is significantly influenced by temperature. Higher temperatures cause more
ions to be released into solution, increasing conductivity. The effects of temperature can
be accounted for by comparing the conductivity at the standard temperature of 25°C,
which is referred to as specific conductance (USGS, 2010). Conductivity is also influenced
by external factors, including geology, soils and climate. Dissolved ion concentrations are
much higher in streams flowing through sedimentary rock that is more easily weathered
compared to igneous and metamorphic rock (Allan and Castillo, 2007). Streams flowing
through clay and silt soils tend to have higher conductivity than inert sandy soils due to
the presence of charged molecules in clays and silts (Essington, 2005). Precipitation and
runoff characteristics can influence stream conductivity. In temperate climates, precipita-
tion events can dilute the dissolved ion concentrations in surface waters. In some cases,
however, more precipitation can increase conductivity if rainwater has a higher concen-
tration of dissolved solids compared to the receiving stream water. Arid climates have
surface waters with high conductivity due to less rainfall. Salts accumulate in soils with
little precipitation and high evaporation, readily dissolving in surface water runoff and
groundwater (Walling, 1984; Allan and Castillo, 2007).
Conductivity measurements comparable to reference stream conditions are maintained in
stream systems when the following conditions are present:
• Low pollutant loads in watershed runoff and point-source discharges, which elimi-
nates direct impact of flows with higher conductivities than those inherent in the
receiving stream; and
• Established riparian buffer, which provides shade to stabilize temperatures, allows
filtration of surf ace-runoff contaminants, and decreases evaporation that can concen-
trate dissolved ions.
pH
Measurements of pH indicate the relative acidity or alkalinity of water. The pH scale
(0-14) measures the logarithmic concentration of hydrogen (H+) and hydroxide (OH-)
ions that compose the water (H2O) molecule. The pH is 7.0, or neutral, when both ions
are in equilibrium, such as in pure water. Streamwater contains dissolved ions that
interact with these water ions to alter the equilibrium. When the pH drops below 7.0, the
water is considered acidic; when the pH is above 7.0, water is considered alkaline (USEPA,
1997b). Stream pH can have a significant effect on biological communities, which prefer
pH values in the 6.5 to 8.0 range. Diversity can be reduced in streams with pH outside
A Function-Based Framework » May 2012 175
-------
Chapter 9: Physicochemical, Water Quality
this range, favoring only certain species that can tolerate more extreme pH conditions
(Hynes, 1970). Like condutivity, pH is a good screening tool for stream restoration proj-
ects. At low pH values, ions from metals and toxic compounds can be released into the
water column and negatively impact biological communities (Allan and Castillo, 2007).
Stream pH can be influenced by chemical reactions and dissolved constituents present
in the water. In natural streams, H+ and OH- ions are typically produced during the
dissociation or hydrolysis of carbon compounds (Wetzel, 2001). Conductivity can be
altered by changes in pH, and vice versa, due to the interaction between water ions and
dissolved ions present in the water column. The effects of temperature on stream pH are
similar to those experienced by conductivity (Stumm and Morgan, 1996).
The pH of streams can be controlled by precipitation and runoff, as well as by soils
and geology. Precipitation typically has an average pH of 5.6 due to the dissolved ions
captured in the atmosphere. An increase in atmospheric pollution from anthropogenic
sources can create acid rain, with even lower pH values (USEPA, 2008). Watershed runoff
can increase the acidity of streamflow, depending on the amount of precipitation, runoff
volume and contaminants carried from the surface. Streams that flow through soils with
high organic acid content, such as wetlands and swamps, generally have inherently lower
pH values. Streams that flow through soils with high carbonate and hydroxide content,
such as those derived from limestone, have higher pH values due to the buffering capacity
provided when binding with hydrogen ions of acids occurs. Weathering of sedimentary
rock produces alkaline soils, while soils derived from igneous rock are low in alkalinity
(Wetzel, 2001). The effects of groundwater inputs on stream pH are similar to conductiv-
ity, due to the relationship between groundwater and surrounding soil chemistry.
Stream pH values comparable to reference conditions are maintained in stream systems
when the following conditions are present:
• Low pollutant loads in watershed runoff and point-source discharges, which elimi-
nates direct impact of flows with higher conductivities than those inherent in the
receiving stream; and
• Established riparian buffer, which provides shade to stabilize temperatures, allows
filtration of acid rain and surface runoff contaminants, and decreases evaporation that
can concentrate dissolved ions.
Turbidity
Turbidity is a measure of water clarity based on how much light passes through the
water column (USEPA, 1997b). Turbid water appears colored or cloudy due to suspended
and dissolved materials, including soil particles, organic matter, plankton and dyes
(USGS, 2010). Turbidity influences other Physicochemical parameters and significantly
impacts biological communities. When the water is turbid, temperatures increase due to
higher absorption of heat by the suspended particles. Dissolved oxygen can be reduced as
a result of increased temperatures and reduced photosynthetic activity when light pen-
etration is impeded. Biological lifecycles and habitats are negatively affected by high
A Function-Based Framework » May 2012 176
-------
Chapter 9: Physicochemical, Water Quality
turbidity. In the water column, suspended materials can reduce visibility needed for
feeding activities and disrupt respiration, such as clogging of fish gills. As the fine par-
ticles settle, they blanket the stream bottom covering substrates used for habitat, and
they fill interstitial spaces of the hyporheic zone where oxygen exchange occurs. High
turbidity for extended lengths of time will reduce reproduction and development of
aquatic organisms (Hynes, 1960; USEPA, 1997b).
Natural causes of turbidity are observed in streams with high plankton productivity, as
well as in streams that flow through organic soils with dissolved humic acids (Hynes,
1970). Turbidity can also be caused by watershed runoff, flow dynamics and channel
instability. Fine sediment particles, such as clays, silts and fine sands derived from an-
thropogenic activities, are common causes of turbidity, particularly in disturbed water-
sheds and unstable stream channels (Whipple et al., 1981). These particles are entrained
in stormwater runoff over bare soils during development of the watershed or with agri-
cultural activities (Wolman and Schick, 1967; USEPA, 2003a). Developed watersheds
with impervious surfaces deliver larger volumes of runoff at a faster rate, accelerating
streambank erosion as the channel becomes increasingly unstable. Studies have shown
that turbidity can remain elevated long after a storm event has ended in disturbed water-
sheds due to channel instability (Hammer, 1972; Whipple et al., 1981). Fine sediment
particles can also have adsorbed nutrients that enrich the streamwater. The excess nutri-
ents increase microbial productivity and biomass to perpetuate the turbidity problem.
Fine sediment particles may also carry pollutants that are detrimental to aquatic life, such
as pesticides and metals (Hynes, 1960).
Stream restoration projects can include several methods to control turbidity. Stabiliz-
ing the watershed and treating turbid stormwater runoff are desired practices in coordina-
tion with a reach-scale restoration project. Designing a channel with floodplain connec-
tivity will provide for sediment deposition outside of the main channel and reduce shear
stress during large storm events. Creating a stable channel that can convey the water and
sediment delivered from the watershed effectively and protecting streambanks from
shear stress will prevent channel erosion as a source of fine sediments in the water col-
umn. Establishing a riparian buffer will significantly reduce fine sediment in runoff,
while increasing infiltration for reduced runoff volume.
Low turbidity concentrations occur in stream systems when the following conditions are
present:
• Watershed stability, which prevents entrainment of fine sediments and associated
nutrients from exposed watershed soils;
• Floodplain connectivity, which promotes sediment deposition on the floodplain and
not within the channel, provides energy dissipation, and reduces channel erosion
during large storm events.
• Channel stability, reducing stream bed and streambank erosion; and
• Established riparian buffer, which slows runoff rates for deposition of fine sediments
and associated pollutants, and provides streambank stability for less erosion.
A Function-Based Framework » May 2012 177
-------
Chapter 9: Physicochemical, Water Quality
Measurement Method
In order to measure basic water quality parameters effectively, a stream monitoring
plan must be developed that considers the significant spatial and temporal variability of
the parameters, as well as fluctuations caused by flow conditions. Collecting individual
(discrete) samples provides information about the parameter at one point in time, which
may yield limited information in lotic systems with such dynamic variability. Continuous
monitoring is recommended in order to better capture variability and allow for compari-
son over time and between the target reach and reference reach. In order to demonstrate
whether significant changes have occurred over time, the number of samples and frequency
of collection are important for statistical analyses of results. The level of effort for water
quality parameters is rapid for discrete samples, but is considered intensive for continu-
ous monitoring used to capture high variability. The level of complexity for all the water
quality measurement methods is considered simple to moderate, depending on the instru-
ments used and the statistical detail or level or expertise required for analyses to deter-
mine deviation from the reference condition and species requirements (Appendix Ac).
When measuring basic water quality parameters to determine Physicochemical func-
tion of a restored stream, it is imperative to identify influential variables that cannot be
affected by restoration at the reach scale. External discharges from upstream, point-source
and non-point-source contributions, and the effects of land-use changes in the watershed
are all variables that may not be included in a reach-scale project. In order to fully restore
these water quality parameters, a watershed scale effort may be required along with the
presence of a healthy upstream watershed. These variables demonstrate that site selection
and reach length must be considered during the planning stage of a stream restoration
project. Climate, geology and soils can also have a significant effect on basic water qual-
ity but cannot be controlled at any scale. Environmental variables that are beyond the
scope of the restoration plan can be differentiated from variables that are controllable
through comparisons with upstream, downstream and reference stream conditions.
The measurement methods listed below are brief summaries for each basic water
quality parameter. All measurement methods are considered direct assessments of water
quality parameters for Physicochemical function (Appendix Ac). Details for each method
can be found in the associated references, as well as outlined in the Standard Methods for
the Examination of Water and Wastewater (Eaton et al., 2005). There are many resources
to assist with deriving a monitoring plan, including those published by state environmen-
tal agencies and federal agencies, such as the USEPA (1997b) guide, Volunteer Stream
Monitoring,: A Methods Manual Recommended references for methods and sampling plans
include Methods in Stream Ecology (Hauer and Lamberti, 2006) and Limnological Analyses
(Wetzel and Likens, 2000).
1. Temperature
Temperature is typically recorded in degrees Celsius for metric units and degrees
Fahrenheit for English units. Temperature can be measured using a standard liquid-in-
glass thermometer, electronic thermistor or thermocoupler in-situ (Hauer and Hill 2006).
A Function-Based Framework » May 2012 178
-------
Chapter 9: Physicochemical, Water Quality
Temperature sensors are commonly included with meters and probes that measure other
parameters, including dissolved oxygen, conductivity and pH; therefore, a separate device
may not be needed (USGS, 2010). Calibration of all devices with a NIST-certified ther-
mometer is recommended (Eaton et al., 2005).
Temperature can be one of the most variable stream parameters to measure. This variabil-
ity should be captured to the fullest extent possible, considering how many Physicochemical
parameters and Biological (Level 5) functions are affected by changes in temperature.
External factors that affect temperature should also be taken into account during
monitoring. Air temperature and precipitation should be measured, and sampling loca-
tions should be selected with the understanding that riparian canopy and external dis-
charges, especially from groundwater seepage, can significantly influence water tempera-
ture. Therefore, the purpose of the sampling should be determined before the
temperature sensors are deployed. Localized influences on temperature, like groundwater
seepage, should be avoided if the goal is to determine a well-mixed, average temperature.
Alternatively, sensors may be deployed in areas with groundwater seepage if the influ-
ence of groundwater and surface water exchange need to be determined.
2. Dissolved oxygen
Dissolved oxygen (DO) is measured as a concentration (mg/L) or as a percentage of the
amount required for complete saturation of the water column. Saturation is based on the
total amount of oxygen that can be dissolved in pure water at a specific atmospheric
pressure and water temperature. Reference tables are available to determine what these
DO concentrations should be (Mortimer, 1981; Eaton et al., 2005). DO should be mea-
sured in-situ or immediately after sample collection to avoid changes in concentrations
associated with microbial processes and temperature. For in-stream measurements, a
probe and meter combination can be used. The most common DO probes have selectively
permeable membranes or optical sensors to detect DO within the water column. When
using a probe and meter, temperature and barometric pressure should also be measured to
adjust DO measurements to environmental conditions (USGS, 2010). In order to measure
DO concentrations using water samples, the method must immediately stabilize DO in
the water column. A common method is the Winkler titration that uses reagents added in
the field prior to titration (Hauer and Hill, 2006). Although the Winkler method is typi-
cally not as accurate as a meter and probe combination, it is generally more economical.
Due to the variability of DO along the stream length and its requirement by many
organisms, the sampling protocol should include measurements from different stream
features,e.g., pool, riffle, upstream and downstream of an impoundment, stream areas
with different riparian cover densities, and near areas where significant external flow
contributions are suspected, e.g., groundwater seeps and springs, stormwater, point sources).
3. Conductivity
Conductivity is commonly measured with a probe and meter combination that mea-
sures resistance by dissolved ions to an electric charge in units of milliSiemens (mS)/cm
A Function-Based Framework » May 2012 179
-------
Chapter 9: Physicochemical, Water Quality
or milli-ohms (mhos)/cm (USEPA, 1997b; Eaton et al., 2005). A temperature sensor is
most always included with the conductivity probe and meter due to the relationship
between the two parameters. Specific conductance is a measure of conductivity that has
been normalized to unit length at the standard temperature of 25 °C (USGS, 2010).
Conductivity measurements indicate the amount of total dissolved solids (TDS) within
the water column. Actual TDS can be calculated by multiplying the conductivity reading
by an empirically determined factor between 0.55 and 0.9 (Eaton et al.; 2005). Conductiv-
ity measurements also provide useful baseline data that can indicate changes in water
quality over time, particularly due to additions of external discharges and pollutants.
4. pH
The pH value can be collected in the field or laboratory using a color treatment test or
using a pH probe and meter combination. Samples collected should be evaluated within
two hours due to the effects of CO2 exchange with air on pH; therefore, field measure-
ments are generally easier and more accurate. For the color treatment test, reagents are
added to the sample causing coloration of the water. The color and its intensity are
compared to a standard color chart to determine the estimated pH unit. For a more
accurate measurement, a pH meter and probe can be used (USEPA, 1997b). The pH meter
measures hydrogen ion activity as a function of electric potential generated between a
glass pH electrode and a reference electrode. Results are reported by the meter in pH units
or millivolts. Temperature should also be measured by the probe to compensate pH
measurements for water temperature (USGS, 2010).
5. Turbidity
Turbidity can be measured directly using a turbidity meter and probe in the field or by
laboratory analysis. The meter uses a light source and a photoelectric cell to measure light
intensity that is scattered and absorbed by suspended and dissolved particles in water.
Without turbidity, light would be transmitted in straight lines through a sample. The
most common unit is the Nephelometric turbidity unit (NTU), and most meters measure
a range from 0 to 1000 NTU (USEPA, 1997b and USGS, 2010). Turbidity can be measured
indirectly using a Secchi disk in deep, slow-moving rivers (Wetzel and Likens, 2000) or
using a transparency tube (USEPA, 1997b).
Turbidity is highly dependent on streamflow with typical increases as stage rises
during storm events that entrain excess sediments during surface runoff and within the
channel. Measurements taken during or immediately after rain events or snowmelt will
result in higher turbidity readings. It is recommended that streamflow measurements be
recorded over time, along with continuous monitoring of turbidity, to capture changes
during storm events. Baseflow samples alone will not yield information about turbidity
levels and their potential impacts on the biological community.
A Function-Based Framework » May 2012 180
-------
Chapter 9: Physicochemical, Water Quality
Performance Standard
Since external factors such as upstream discharges, point-source discharges and water-
shed land use changes cannot always be controlled, it is important to measure basic water
quality parameters within the proposed restoration reach prior to construction, as well as
within the reference stream(s). Measurements should also be taken upstream and down-
stream of the restored reach to determine what is coming into and exiting the restored
reach. These locations will provide baseline measurements of existing and reference
conditions for each parameter for comparison of post-restoration performance.
Existing condition and reference stream measurements along with water quality
standards should be used when assessing the functionality of stream chemistry. To
determine whether or not an aquatic system is meeting its pre-determined designated
use, regulators use water quality standards. The designated uses are determined by
taking into consideration the desired use and value of a stream for public water supply,
protection of fish, shellfish and wildlife, and for recreational, agricultural, industrial and
navigational purposes (USEPA, 2011). Streams meeting these standards are only meeting
the minimal requirements determined for the use by the state in which the system is
located. Water quality standards vary depending upon specific state regulations; there-
fore, it is recommended that monitoring programs use their state's standards as the
minimum requirements for stream assessment. The EPA has compiled a database of each
state's water quality standards on their website (www.epa.gov/waterscience/standards/
wqslibrary; USEPA, 2007). EPA has also compiled water quality monitoring information
from across the country. This data set is available at www.epa.gov/storet.
Reference conditions and certain species requirements may exceed the water quality
standards, depending on the designated use. An example in the East would be restoring a
stream for native brook trout, which would have higher water quality standards than
restoring a stream for recreational fishing of rainbow trout, due to species requirements.
Both measurements from reference streams and appropriate water quality standards for
the desired use are, therefore, the best assessments to determine if the project reach is
Functioning. Measurements that only meet the minimum water quality standards, but
are not representative of the reference stream conditions and are limiting to certain
species, are considered Functioning-at-Risk; those not meeting minimum water quality
standards, not representative of the reference conditions, and not supporting species
requirements should be considered Not Functioning. For parameters that do not have
water quality standards, reference conditions and species requirements are used to
determine performance level (Table 9.2). Turbidity may or may not have regulated water
quality standards, depending on the location; therefore, turbidity is listed in both catego-
ries in the table.
A Function-Based Framework » May 2012 181
-------
ChapterS: Physicochemical, Nutrients
TABLE 9.2 BASIC WATER QUALITY PERFORMANCE STANDARDS
MEASUREMENT
METHOD
FUNCTIONING
FUNCTIONING-AT-RISK
NOT FUNCTIONING
Temperature
DO
Turbidity
Conductivity
pH
Turbidity
Meets water
quality standards
for designated
Meets water quality
standards for designated
use
use
Does not meet
water quality
standards for
designated use
Is not representative of
Representative of reference stream Is not representative
reference stream conditions and does not of reference stream
conditions and support species
meets species
requirements
Representative of
requirements
Is not representative of
reference stream reference stream
conditions and conditions or
conditions and does
not support species
requirements
Statistically
different than
reference stream
meets species conditions and
requirements Does not support species |
requirements
Does not support
species
requirements
9.2 » PARAMETER: NUTRIENTS
Description
Nutrients are chemical elements required by all organisms to live and grow. The most
important nutrients found in both aquatic and terrestrial ecosystems are nitrogen and
phosphorus due to their influence on growth (Allan and Castillo, 2007). Nitrogen is found
in dissolved inorganic form primarily as nitrate (NO3-) and ammonium (NH4+) ions, and
as organic nitrogen. Nitrogen enters the stream through precipitation, atmospheric depo-
sition and diffusion, in situ nitrogen fixation, groundwater, and surface runoff. Phospho-
rus is present as inorganic phosphate (PO4+) and as organic phosphorus (USEPA, 1997b).
Both inorganic and organic phosphorus can be dissolved in water or suspended in the
water column as living biomass or attached to solid particles within the sediments (USE-
PA, 1997b; Allan and Castillo, 2007). Phosphorus enters the stream mainly through
weathering of soils and rock and adsorbed to soil in surface runoff (Hynes, 1970).
In natural streams, most nutrients are stored within the biomass of the biological
community. Nutrient uptake by living organisms is in equilibrium with nutrient release
during excretion and decomposition of dead organic matter. Dissolved inorganic forms of
nitrogen (NO3- and NH4+) and phosphorus (PO4+) are present in very low concentrations
(Hynes, 1970; Maybeck 1982). Dissolved nutrients move downstream, continuously
cycling between abiotic and biotic forms, and between inorganic and organic forms, in a
process known as nutrient spiraling. Dissolved inorganic nutrients are assimilated by
A Function-Based Framework » May 2012
182
-------
ChapterS: Physicochemical, Nutrients
living organisms, bound to sediments or chemically transformed, moving from the water
column to sediments and then released again for downstream transport (Stream Solute
Workshop, 1990; Newbold, 1992). Nutrient cycling can help maintain water quality by
sequestering nutrients within the biological community and substrates, reducing down-
stream nutrient loads. The nutrient spiraling equilibrium can be significantly disrupted,
however, by excess nutrient inputs. Details of nutrient spiraling can be found in Stream
Solute Workshop (1990) and Webster and Valett (2006).
Excess nutrients are contributed from anthropogenic sources such as fertilizers, animal
waste and sewage from agricultural runoff, urban runoff and direct point-source dis-
charges (Figure 9.3; USEPA, 2000). Nitrogen is also added from atmospheric pollutants
through precipitation, commonly referred to as acid rain (USEPA, 2008). Excess nutrients
in the stream can over-stimulate microbial productivity causing eutrophication (Figure
9.4; USEPA, 2000). Excess nutrients from nonpoint sources are one of the leading causes
of stream impairment in the nation (Carpenter et al., 1998; Allan, 2004; USEPA, 2009).
There are several processes that can naturally remove excess nutrients from the water
column. Nitrogen can be assimilated into biomass, removed through denitrification,
adsorbed to sediments and volatilized (Bernot and Dodds, 2005). Phosphorus is removed
from the water column by assimilation and adsorption to sediments (USEPA, 1997b).
Nutrient storage processes can be temporary, however, so the most effective way to
reduce excess nutrients in streams is to control the sources from the watershed.
Stream restoration projects can include several techniques to reduce excess nutrients.
Establishing floodplain connectivity is important for deposition of nutrient-laden sedi-
ments outside the channel, and for providing a healthy riparian buffer that can store
nutrients. A riparian buffer can remove nutrients if the root zone is in contact with the
groundwater table to facilitate denitrification. In-stream modifications that restore incised
channels to proper geomorphic dimensions will connect the riparian buffer to the
groundwater table. Channel modifications that increase stream length and residence time
will promote nutrient uptake by the biological community and denitrification (Gucker
and Pusch, 2006). (See Figure 9.5.) Channel stability will also reduce nutrients in the
water column by conveying water and sediments effectively, by preventing sediment
inputs from streambank erosion, and by maintaining a healthy hyporheic zone where
microbial processes can sequester nutrients (Hendricks, 1993).
Removal of excess nutrients occurs in stream systems when the following conditions
are present:
• Nonpoint sources of excess nutrients are controlled;
• Floodplain connectivity facilitates sediment deposition, provides sediment storage,
and establishes the water table to be in contact with the root zone of the riparian
buffer, which is required for dentrification to occur;
• Established riparian buffer, which slows runoff rates and facilitates sediment deposi-
tion with associated nutrients, stabilizes streambanks and provides nutrient uptake by
riparian vegetation;
A Function-Based Framework » May 2012 183
-------
ChapterS: Physicochemical, Nutrients
• Meandering channel increasing stream length, which decreases stream velocity and
increases hydrologic residence times (required processes for nutrient processing);
• Channel stability, which reduces streambank erosion and fine sediment inputs; and
• Healthy hyporheic zones, promoting habitat for the microbial community that pro-
cesses nutrients.
FIGURE 9.3 SOURCE OF LATERAL RUN-OFF FIGURE 9.4 AREA OF NUTRIENT ENRICH-
FROM GOLF COURSE MENT DOWNSTREAM OF GOLF COURSE
Source: Reproduced with permission from Michael Baker Source: Reproduced with permission from Michael Baker
Corporation Corporation
FIGURE 9.5 RESTORED MEANDERING CHANNEL
Source: Reproduced with permission from Michael Baker Corporation
Restored meandering channel that is well connected to the floodylain. The water table is in contact
with the newly established stream buffer. The meandering channel with diverse bed forms and
complexity increase the hydrologic residence times. Together, these elements support nutrient processing.
A Function-Based Framework » May 2012
184
-------
ChapterS: Physicochemical, Nutrients
Measurement Method
Chemical measurements for nutrients can be conducted in the field or in a laboratory,
dependent upon the measurement method used and the desired accuracy of results. Field
test kits are available for the rapid and simple assessment of many nutrient forms, usually
containing reagents and a color wheel/colorimeter to determine concentrations. Many of
the nutrient tests performed in the laboratory use specialized analytical equipment and
complex chemical reactions for better accuracy. For details on these analytical methods,
refer to Eaton et al., (2005). The level of effort for nutrient measurements ranges from
rapid to intensive, depending on the instrument used and the number of samples required
to capture variability and to determine deviation from reference conditions. The level of
complexity is considered simple when using field test kits, but complex when laboratory
analysis is required (Appendix Ac).
Nitrogen concentrations (mg/L) can be measured by analyzing water samples for
inorganic forms, including nitrate (NO3) and ammonia (NH3). Nitrite (NO2) is an interme-
diate inorganic form produced during denitrification (NO3 to nitrogen gas) and nitrifica-
tion (NH3 to NO3). However, it is generally not measured due to its very minute concen-
trations at any given time. Nitrate is important to quantify because it is readily produced
by oxidation of ammonia (nitrification), readily dissolved in water and leached from soils,
and an essential nutrient for primary producers (Wetzel, 2001; Eaton et al., 2005). Nitrate
can be analyzed in the field with an electrode and meter combination; however, this
method is currently unable to detect quantities of less than 1 mg/L. Nitrate can also be
quantified using the cadmium reduction method in which NO3- reacts with cadmium
ions to produce a color reaction that can then be interpreted for concentration. Ammonia
concentrations are generally low in natural streams, since ammonia does not readily leach
from soils and is rapidly converted to NO3 for biological assimilation. Ammonia can be
analyzed in the field with an electrode and meter combination or using a salicylate
reagent method (USEPA, 1997b; Eaton et al., 2005). Other common nitrogen quantities
that can be measured are briefly described to assist with parameter selection. These quan-
tities can be combined with nitrate and ammonia tests in various ways to estimate
individual nitrogen components, including organic N concentrations. Total nitrogen (TN)
is the sum of all nitrogen forms, inorganic and organic. It can be quantified in the labora-
tory using a persulfate digestion method. Total Kjeldahl nitrogen (TKN) is named for the
method used and is the sum of organic N and ammonia concentrations (Wetzel and
Likens, 2000; Eaton et al., 2005).
Phosphorus concentrations (mg/L) can be measured by analyzing water samples for
(ortho)phosphate (PO4) using the ascorbic acid method. To determine total phosphorus
(TP) concentrations (organic and inorganic), the sample is first digested with an acidic
solution containing a strong oxidizer that first converts all forms to phosphate (PO4) in
preparation for the ascorbic acid test. These two values allow for determination of organ-
ic P. The dissolved phosphorus portion can be determined in water samples by filtering
out the phosphorus associated with suspended particles first, then using the above phos-
phate and TP methods. An important form to measure is the soluble reactive phosphorus
A Function-Based Framework » May 2012 185
-------
ChapterS: Physicochemical, Nutrients
(SRP), which is the soluble inorganic PO4 fraction available for biological assimilation. It
is determined by subtracting the filtered PO4 concentration from the original PO4 concen-
tration (Wetzel and Likens, 2000; Eaton et al.; 2005).
When measuring nutrients within a stream reach, the process of nutrient spiraling
should be accounted for since nutrients are being continuously cycled between inorganic
and organic states, and between the biological community, substrate and the water
column (Newbold, 1992). Adequate upstream and downstream sampling before restora-
tion activities occur is recommended in order to get a good baseline survey of nutrient
concentrations entering and exiting the reach. Nutrient cycling can also result in signifi-
cant nutrient storage within microbial biomass and bottom sediment over long periods of
time. Stored nutrients can be reintroduced into the water column under certain stream
conditions, causing persistent nutrient release long after the pollutant source has been
removed. It is recommended that post-restoration monitoring occurs over a sufficient time
period to evaluate whether nutrient reductions have been achieved (USEPA, 2000).
Nutrient processing methods are not discussed due to their relative complexity compared
to water sample analyses. But these methods are recommended if a more detailed assess-
ment is allowed by time and funding. Resources for these processing methods include
Newbold et al. (1981), Payn et al. (2005), and Hauer and Lamberti (2006).
External discharges entering the stream reach of interest along with watershed activi-
ties affect nutrient concentrations and must be accounted for in nutrient monitoring
plans. Nutrients should be measured within the proposed project reach before and after
restoration. Baseline sampling should also occur upstream and downstream of the project
reach and within the reference reach for comparisons over space and time. It is recom-
mended that nutrient monitoring extend far enough downstream to observe nutrient
cycling effects. This distance would be dependent on the nutrient load, the availability of
nutrient sinks and flow rate. A nutrient with/without tracer release study can be used to
determine specific distances. It is recommended that nutrient monitoring also occur for
an extended period of time after restoration to observe the effects of nutrient storage.
Comparisons between existing condition and reference reach measurements along with
state water quality standards should be used when assessing nutrient loads.
Performance Standard
Performance standards for nutrients are similar to basic water quality parameters. Due
to the predominance of excess nutrients in aquatic systems, the nutrient parameters are
evaluated based on amount of eutrophication versus biological limitations. Both measure-
ments from reference streams to establish reference condition and appropriate water
quality standards for the desired use can be used to determine whether a project stream
is Functioning. It is assumed in this performance standard that the reference stream
condition will meet species requirements to qualify as a suitable comparison reach.
Measurements that only meet the minimum water quality standards, but are not repre-
sentative of the reference stream condition and are limiting to certain species, are consid-
ered Functioning-at-Risk; those not meeting minimum water quality standards, not
A Function-Based Framework » May 2012 186
-------
Chapter 9: Physicochemical, Organic Carbon
representative of the reference stream condition and not supporting species requirements
should be considered Not Functioning. For nutrients that do not have water quality
standards, reference conditions and species requirements are used to determine perfor-
mance level (Table 9.3).
TABLE 9.3 NUTRIENT PERFORMANCE STANDARDS
MEASUREMENT
METHOD
Field Test Kits
and Laboratory
Analysis
FUNCTIONING
Meets water quality
standards for
designated use
FUNCTIONING-AT-
RISK
Meets water quality
standards for
designated use
Representative of Is not representative
NOT FUNCTIONING
Does not meet water
quality standards for
designated use
reference stream of reference stream Is not representative
conditions conditions | of reference stream
Does not cause
eutrophication
Does not cause
eutrophication
conditions
Causes eutrophication
9.3 » PARAMETER: ORGANIC CARBON
Description
Energy is made available in lotic ecosystems through metabolism of organic carbon. The
majority of organic carbon is added from outside the stream channel, referred to as
allochthonous. This material is contributed from riparian vegetation and soil organic
matter. The remainder of organic carbon is generated within the stream channel, referred
to as autochthonous. This material is contributed from organic processing, particularly
through photosynthesis by macrophytes and algae (Allan and Castillo, 2007). The largest
proportion of OC is non-living (detritus) and not associated with living biomass (Wetzel,
2001). Organic carbon availability significantly influences the biological community in
streams. Small streams with dense canopies and limited photosynthesis rely mostly on
microbial uptake and decomposition of OC for energy transfer to higher trophic levels. In
larger rivers microbial metabolism is still important, even with additional photosynthesis
opportunity due to turbidity, depth, downstream transport of OC and floodplain inputs
(Vannote et al, 1980).
Organic carbon can either be in dissolved (DOC) or particulate form (POC), and
generally composes half of organic matter (OM) on a weight basis (Allan and Castillo,
2007). Due to this consistent relationship between the two organic forms, these terms
are commonly used interchangeably in the literature. Dissolved organic carbon (DOC) is
commonly the largest pool available to the biological community on an annual basis, and
the ratio of DOC:POC is greater than 1 inmost streams (Maybeck, 1982; Webster and
Meyer, 1997). DOC is composed primarily of humic materials derived from organic
A Function-Based Framework » May 2012
187
-------
Chapter 9: Physicochemical, Organic Carbon
matter in soils and contributed through groundwater to the stream. Within the stream,
DOC is assimilated by the microbial community or produced by microbial processing of
larger particulate organic materials within the substrate hyporheic zone. DOC can also
be transformed by abiotic processes such as precipitation, flocculation, and adsorption to
soil particles, and direct mineralization by sunlight. DOC is processed rapidly, generally
within days (Wetzel, 2001). Particulate organic carbon (POC) is commonly referred to in
the context of organic matter, and is divided into fine particulate organic matter (FPOM)
and coarse particulate organic matter (CPOM). FPOM is generally between 0.5pm and
1mm and is derived from the decomposition of CPOM in the form of plant litter and
woody debris (Wetzel, 2001). It can be found floating in the water column (seston) or
within the bottom sediments (Wallace et al., 2006). CPOM is anything greater than
1mm, providing an important fixed carbon source to streams (Lamberti and Gregory,
2006; See Level 3, Organic Matter Transport). Particulate forms of organic matter are
generally processed over weeks (FPOM) to years (CPOM) by microbial decomposition or
direct consumption by higher trophic levels, including macroinvertebrates and fish. The
amount of POC available in the stream is dependent on the amount of riparian vegetation
present, watershed runoff characteristics and streamflows (Wetzel, 2001).
Organic carbon processing occurs in a similar pattern as that of nutrients, through
carbon spiraling moving downstream (Newbold et al., 1982). Organic carbon is assimi-
lated by living organisms, adsorbed to bottom sediments, or abiotically transformed in a
cyclical pattern. Biological metabolism either transfers organic carbon up the food chain
during consumption, or remineralizes it to inorganic carbon dioxide gas (CO2) that is
released into the water column. These processes can be complex, and details can be
found in Newbold et al. (1982), Thurman (1985) and Webster and Benfield (1986). Organ-
ic matter budgets can be created for streams to quantify organic carbon pools and their
availability (Cummins et al., 1983; Webster and Meyer, 1997). Due to the importance of
organic carbon in lotic systems, stream restoration practitioners should always consider
how to enhance organic carbon availability within their projects. The establishment of
lateral connectivity between the stream and riparian zone can provide significant OC
sources (Gregory et al., 1991; Lake et al., 2007). A riparian buffer contributes both DOM
and POM directly from vegetation and watershed surface runoff, and indirectly by
enhanced infiltration through the soil to groundwater (Figure 9.6). Floodplain connectivity
exposes streamflow to OM sources in the riparian areas and prevents excessive removal
of POM by hydraulic scouring during large flow events. Designing a stable channel that
can maintain a healthy hyporheic zone with adequate groundwater interaction and
oxygen availability is essential for organic processing and has been well documented
(Stanford and Ward, 1988; Kasahara and Hill, 2006; Kasahara, 2007; Boulton et al., 2010).
Restoring a meandering pattern with deep pools and installing structures, such as root
wads, large woody debris (LWD) and cross vanes, will enhance retention of organic
materials (James and Henderson, 2005). (See Figure 9.7.)
A Function-Based Framework » May 2012 188
-------
Chapter 9: Physicochemical, Organic Carbon
Organic carbon availability and processing occurs when the following conditions
are present:
• Established riparian buffer, which contributes OC directly through vegetation and
indirectly through infiltration to groundwater;
• Floodplain connectivity, providing access to riparian vegetation and organic matter
and reducing stream velocities during high flows;
• Healthy hyporheic zones, which promote habitat for the microbial community that
processes OC and provides a groundwater interface for DOC contributions; and
• Channel meandering and in-stream structures, which create opportunities for OM
storage in deep pools and increase POM retention.
FIGURE 9.6 RIPARIAN BUFFERS PROVIDE ALLOCHTHONOUS MATERIAL
Source: Reproduced with permission from Michael Baker Corporation
Figure 9.6 is an urban stream restoration project six years after construction. The photo was taken in
the Fall and shows leaves falling from the riparian buffer into the stream channel.
A Function-Based Framework » May 2012
189
-------
Chapter 9: Physicochemical, Organic Carbon
FIGURE 9.7 ROOT WADS AND MEANDER BENDS HELP RETAIN ORGANIC MATERIAL
Source: Reproduced with permission from Michael Baker Corporation
Measurement Method
The relative amount of organic carbon in a water sample (mg/L) is determined using
laboratory analyses. These methods are considered intensive for the level of effort and
complex for the level of complexity, due to the different samples that must be collected to
evaluate the different forms of organic carbon, due to the equipment required, and due to
the level of expertise needed to interpret the measurement results in comparison to the
reference condition (Appendix Ac).
Filtration is generally used to separate out the CPOM portion (1mm), the FPOM
(0.45pm) and the dissolved fraction (DOC). The dissolved portion is then quantified
using a of total organic carbon (TOG) analyzer after removing the inorganic carbon
fraction (CO2, bicarbonate and carbonates). The analysis method uses high temperature
combustion or UV/persulfate oxidation. POC concentrations (mg/L) in each size class are
determined by placing the filtered portion from the water sample into a high temperature
oven (550 °C) and quantifying mass lost upon combustion (Wetzel and Likens, 2000;
Eaton etal., 2005).
Measurement methods of organic carbon associated with substrates and bottom
sediments, primarily DOC and FPOC, are not described in this section. These measure-
ments, along with inorganic carbon (CO2) methods, are described in Level 5: Microbial
Communities. Specific methods of measuring organic carbon can also be found in Wetzel
and Likens (2001), Eaton et al., (2005), and Hauer and Lamberti (2006). Retention of
CPOM, particularly leaves and small woody debris, can be estimated using methods
described in Ehrman and Lamberti (1992) and James and Henderson (2005). In general,
A Function-Based Framework » May 2012
190
-------
Chapter 9: Physicochemical, Organic Carbon
the retention and release of CPOM is modeled by using a log proportional linear regres-
sion equation that compares the amount of CPOM remaining in the system to the dis-
tance it has traveled within the system.
Similar to nutrient measurement methods, external discharges entering the stream
reach of interest along with watershed activities should be considered due to their effects
on OC quantities. OC concentrations should be measured within the proposed project
reach before and after restoration. Baseline sampling is recommended both upstream and
downstream of the project reach and within the reference stream(s), in order to adequate-
ly compare measurements spatially and temporally. It is recommended that OC monitor-
ing extend far enough downstream and over an extended period of time after restoration
to observe OC spiraling effects, particularly the storage component. Specific measure-
ments of OC spiraling are complex and not covered in this section (see references above).
All measurements should be compared to reference conditions for effective evaluation.
Performance Standard
There are no published performance standards for organic carbon concentrations and
for organic processing in streams. The best evaluation of organic carbon concentrations is
by comparison of quantities with reference reach conditions (Table 9.4). Measurements
that meet reference stream conditions are indicative of a Functioning stream reach.
Measurements where results do not meet reference stream conditions could be considered
Functioning-at-Risk. Measurements of OC concentrations that do not meet reference
stream conditions could be considered Not Functioning. A threshold can be determined
based on biological species biomass and OC processing found in the reference stream.
Suggested performance standards for OC processing are not covered in this section, but
they can be found in Level 5 (Biology) due to the dependence of biological metabolism on
OC concentrations. Species biomass and assemblage measurements, particularly those of
the microbial and benthic macroinvertebrate communities, can be incorporated into
evaluations of effective OC concentrations, if desired.
TABLE 9.4 ORGANIC CARBON PERFORMANCE STANDARDS
MEASUREMENT
METHOD
Laboratory
Analysis
FUNCTIONING
Meet reference
stream conditions
FUNCTIONING-AT-
RISK
Do not meet
reference stream
conditions
NOT FUNCTIONING
Do not meet reference
stream conditions and
is below a threshold
determined for
adequate organic
processing.
A Function-Based Framework » May 2012
191
-------
3.QG iniGniioricuiy LGTI t5i3.riK
A Function-Based Framework » May 2012 192
-------
Chapter 10
Biology
Biology functions are at the top of the Stream Functions Pyramid. These functions
include processes that support the life histories of aquatic and riparian plants and ani-
mals. The ability of the lotic system to support biological processes is dependent upon
the Hydrology, Hydraulic, Geomorphology and Physicochemical functions as described
previously. Stream biological communities have a highly interconnected trophic structure
starting from primary producers and moving up the food chain to fish. When habitat
degradation occurs due to functional loss in the lower levels, and when valuable energy
resources are removed, the trophic structure is disrupted and biological assemblages lose
diversity and abundance.
The Biology function-based parameters include microbial communities, macrophyte
communities, benthic macroinvertebrate communities, fish communities and landscape
connectivity. A variety of measurement methods are provided for each parameter. The
parameters, measurement method and indication of whether or not a performance stan-
dard is provided are shown below in Table 10.1. Scientists have researched the detailed
and complex effects of stream condition on biological function and have developed
biological indices that integrate ecosystem dynamics into simple, rapid assessments of
stream condition. Biological indices are commonly used to assess water quality, but some
have been developed to evaluate overall stream condition. Some of these indices are
provided below and are included in the Biology category even though they also include
parameters from the lower levels, as their purpose is to provide an overall assessment of
biological condition. Appendix Ac includes a list of all the Biological measurement meth-
ods along with information about the method's type, level of effort, level of complexity,
and whether it is a direct or indirect measure of the function-based parameter. The
criteria used to make these determinations are provided in Chapter 4.
Landscape connectivity is included in the Biology category because it represents the
ability of a target aquatic or riparian species to migrate upstream and downstream along
a continuous corridor that meets their habitat requirements. Physical breaks in the corri-
dor, like roads, create a disconnection to their habitat requirements. Landscape connectiv-
ity only becomes important after the species of interest are identified. For example,
landscape connectivity requirements will be different for turtles than for large mammals
like deer and bear. Once the species of interest are identified, landscape connectivity
requirements can be determined.
A Function-Based Framework » May 2012
193
-------
Chapter 10: Biology, Microbial Communities
TABLE 10.1 BIOLOGY PARAMETERS, MEASUREMENT METHODS AND AVAILABILITY OF
PERFORMANCE STANDARDS
PARAMETER
Microbial Communities
Macrophyte Communities
Benthic Macroinvertebrate
Communities
Fish Communities
Landscape Connectivity
MEASUREMENT METHOD
1. Taxonomic Methods
2. Non-Taxonomic Methods
3. Biological Indices
1. Taxonomic Methods
2. Non-Taxonomic Methods
3. Biological Indices
1. Taxonomic Methods
2. Non-Taxonomic Methods
3. Biological Indices
1. Taxonomic Methods
2. Non-Taxonomic Methods
3. Biological Indices
1. Spatial Analysis
2. Species Tracking
3. Habitat Models
PERFORMANCE
STANDARD
No
No
Yes
No
No
Yes
No
No
Yes
No
No
Yes
No
No
No
10.1 » PARAMETER: MICROBIAL COMMUNITIES
Description
The microbial community in lotic systems is the foundation of the food chain, provid-
ing the organic energy to all of the higher trophic levels, including invertebrates and fish.
This community is composed of autotrophs and heterotrophs. Autotrophs are the pri-
mary producers, making organic compounds through the process of photosynthesis with
the uptake of inorganic carbon (CO2) and release of oxygen. Phytoplankton and algae are
the major primary producers within the microbial community. Heterotrophs are the
primary consumers of the food chain, including bacteria and fungi. They break down
particulate organic carbon (POC) and consume dissolved organic carbon (DOC) for
energy, which is transferred to higher trophic levels as they in turn are consumed. This
organic processing occurs through microbial respiration and release of CO2 (Allan and
Castillo, 2007). In most lotic systems, heterotrophic production is the predominant source
of energy input. Primary production becomes significant, however, in higher order streams
and rivers where light is more available (Vannote et al., 1980; Minshall et al., 1985).
The microbial community can be found suspended in the water column, referred to as
plankton or seston, and found inhabiting substrates along the bottom of the stream,
referred to as periphyton. Plankton is defined as any drifting organism, including autotro-
phic phytoplankton and algae, and heterotrophic zooplankton and bacteria. Periphyton is
a complex community of both autotrophic and heterotrophic microbes, including algae,
A Function-Based Framework » May 2012
194
-------
Chapter 10: Biology, Microbial Communities
fungi, bacteria, protist and other species that provide a link between the substratum and
the overlying water column (Wetzel, 1983 and Wetzel, 2001). In lotic systems, periphyton
is generally the most important biological community for providing energy to higher
trophic levels. Energy contributions from plankton communities become important in
larger rivers where light is plentiful and deep water prevents significant periphyton
development. Within the periphyton layers, primary production and heterotrophic
consumption create a microbial loop that effectively cycles carbon and nutrients (Lowe
and LaLiberte, 2006 and Allan and Castillo, 2007). The balance between primary produc-
tion and decomposition within the microbial community can determine the availability
of organic matter and nutrients to higher trophic levels, as well as the amount of oxygen
available for aquatic organisms. For a more detailed discussion of primary producer and
consumer interactions, refer to Lamberti et al. (2006).
Microbial communities are influenced by hydrology, availability of substratum, light,
carbon and nutrients, water quality, and consumer populations (Biggs, 1996; Janauer and
Dokilul, 2006). The availability of stable substrates (including rocks, wood, sediments
and macrophytes) that are exposed to limited scouring during storm events allows for
development of diverse and productive microbial assemblages. Light is required for
primary productivity and determines the extent of periphyton development (Figure 10.1).
Temperature is one of the most important basic water quality parameters that affect
microbial productivity due to thermal regulation of metabolism. Both light and tempera-
ture change daily and seasonally to define microbial population dynamics. The availabil-
ity of carbon as inorganic CO2 for primary producers, and dissolved and particulate
organic carbon (POC) for heterotrophic bacteria and fungi is essential. The hyporheic
zone and flow of interstitial water has a significant influence on periphyton productivity
because it contributes a source of DOC from the groundwater (Boulton et al., 1998;
Wetzel, 2001). Excess nutrients and organic pollution can over-stimulate microbial pro-
duction, however, which is detrimental to streams as oxygen consumption during de-
composition becomes greater than oxygen production (See Physicochemical Chapter:
Nutrients and Organic Carbon). Consumer populations of invertebrates and fish can also
have a considerable effect on microbial communities, especially periphyton, through their
feeding habits (Lamberti, 1996). Although most microbial biomass is consumed as detri-
tus, feeding on living tissues is significant because living tissues are more nutritious
(Cummins and Klug, 1979).
Many of the stream restoration techniques used for Levels 1-4 will help develop a
stable and productive microbial community. Non-point sources of excess nutrients and
organic pollution should be controlled as much as possible within stormwater runoff to
ensure there is a balance within the microbial population that contributes more dissolved
oxygen than consumed. Large fluctuations in stream velocities during stormflow can be
controlled by providing floodplain connectivity and designing a channel to attenuate
erosive flows. Floodplain connectivity can also provide organic carbon resources while
promoting sediment deposition outside of the channel. Periphyton on most substrates is
negatively affected by scour, and may take a long time after large flow events to recolo-
A Function-Based Framework » May 2012 195
-------
Chapter 10: Biology, Microbial Communities
nize and provide food and habitat. Maintaining a stable and healthy hyporheic zone
especially benefits periphyton by providing DOC and nutrient resources. Bed form
diversity is important to create shallow habitats and substrate protected from increases in
stream velocity. Designing a channel for adequate transport of the sediment load and
channel stability will prevent sediment inundation of periphyton substrate and reduce
turbidity that limits light availability for both plankton and periphyton communities.
The presence of large woody debris and in-stream structures can create habitat for micro-
bial communities and help dissipate the energy of higher flows. Overall, stream restora-
tion practices that ensure channel stability and improve water quality will encourage
establishment and balanced growth of microbial communities that will provide dissolved
oxygen, food and habitat for all trophic levels.
A healthy functioning microbial community occurs when the following conditions are
present:
• Removal of excess nutrients and organic pollution, which prevents overstimulation of
microbial productivity that will remove dissolved oxygen;
• Floodplain connectivity and bankfull channel, which dissipate energy of large storm
events to prevent excessive scouring of substrate, provide access to organic carbon
sources available on the floodplain, and prevent sediment inundation of substrate;
• Healthy hyporheic zones, which provide periphyton habitat, and provide an interface
with groundwater and DOC inputs;
• Bed form diversity and in-stream structures, which create shallow habitats for light
availability, dissipate flow energy, provide opportunities for organic carbon storage
and retention, and provide substrates such as large woody debris and rocks; and
• Channel stability that prevents sediment inundation of periphyton habitat and the
detrimental effects of turbidity on plankton and periphyton communities.
FIGURE 10.1 GOOD PERIPHYTON HABITAT IN AN INTERMEDIATE SIZE RIVER WITH SHALLOW
DEPTH, LIMITED SCOUR, AND PLENTY OF AVAILABLE COBBLE SUBSTRATE
Source: Photo by Will Barman
A Function-Based Framework » May 2012
196
-------
Chapter 10: Biology, Microbial Communities
Measurement Method
Microbial community samples are collected from the field and generally brought back
to the laboratory for analysis. Plankton can be collected for measurement from the water
column by filtering techniques using a known water sample volume. Periphyton can be
collected by scraping known areas of natural substrates and various artificial substrates
that have been allowed to colonize over time. The samples can then be analyzed for both
taxonomic and non-taxonomic parameters. Algae are the most common microorganism
evaluated within samples due to their predominance within the microbial community,
as well as because of their well-developed taxonomy and extensive research of their
tolerance to environmental stressors (Hines, 1970; Stevenson and Pan, 1999; Stevenson
and Smol, 2003). Detailed methods for sampling microbial communities and measure-
ment methods can be found in Weitzel (1979), Wetzel (1983), Hill (1998) and Steinman
et al. (2006). A summary of common measurements is presented below, including the
direct methods of taxonomic and non-taxonomic measurements and the indirect method
of the biological index method.
1. Taxonomic Measurements
Species are indentified using visual observations and microscopes. This information is
used to determine species composition, their relative abundance (numbers present),
species diversity and taxa richness. This information is collected in a project reach,
preferably upstream or downstream of the project, and within reference stream(s).
Statistical techniques are used to determine if the populations in the project reach are
different than the reference conditions established using reference stream data.
2. Non-Taxonomic Measurements
Biomass and productivity are two non-taxonomic measures of microbial communities.
For biomass, samples are filtered and the dry weight of the filtered biological material is
determined (105°C oven). Ash-free dry mass is then measured (AFDM; 500°C oven) to
determine biomass on a carbon basis per volume for plankton and per area for periphy-
ton. Chlorophyll a content can also be assessed to estimate algal biomass proportion,
since most all plants contain chlorophyll a in known quantities per species. Microbial
productivity can be measured using several methods. A change in biomass over time is a
measure of microbial productivity. Artificial substrates, such as dowel rods, clay tiles and
Plexiglas plates have been used to evaluate colonization rates over time as a measure of
productivity. These methods must take into consideration the effects of disturbance,
seasonal changes in microbial communities and consumer interactions, and changes in
water quality that may have occurred between sampling dates. For algal species, primary
productivity (mass/volume/time or mass/area/time) can also be assessed using gas
exchange measurements, generally of oxygen in light and dark containers or over a
24-hour period (Hynes, 1970). These measurements assume that primary production (PP)
and community respiration (CR) occur in the light and only CR occurs in the dark. For
benthic studies, specialized chambers have been used with stream substrates enclosed to
A Function-Based Framework » May 2012 197
-------
Chapter 10: Biology, Microbial Communities
measure primary production and respiration (Bott et al.; 1978; Dodds and Brock, 1998).
Net primary productivity (NPP) is the fixed carbon that is stored in biomass and equals
gross primary productivity (GPP) measured in the light minus CR measured in the dark.
Another method involves measuring the rate of the radiotracer (14C isotope) uptake over
time, which is a suitable method for low densities of algae (Peterson and Fry, 1987 and
Finlay, 2001).
3. Biological Index
Microbial communities have become good biological indicators of water quality and
overall stream condition. Their responses to environmental stressors occur over a shorter
time span than other aquatic organisms, and they have higher population turnover rates
to measure response. Algae within the periphyton assemblage are the predominant
members used as biological indicators for reasons stated above (Hill and Herlihy, 2000;
Hill et al., 2000). Algal species have specific response characteristics to habitat loss, and
contamination by nutrients, metals, herbicides, hydrocarbons and acidification. Many
biological indices have been developed for periphyton algae, based on large surveys of
reference data that integrate both taxonomic and non-taxonomic metrics with measure-
ments of stream condition (Karr, 1993). The EPA Rapid Bioassessment Protocol (RBP) for
periphyton can be used to guide the development of these biological indices specific to
different regions and stream types (Hill and Herlihy, 2000). These indices allow for rapid
stream assessments using only a handful of metrics. Measures of microbial communities
should not be used alone, however, due to interactions between these populations and
their consumers, and due to frequent disturbance of assemblages during storm events
(Stevenson, 1996).
The level of effort for all of the measurement methods described above is considered
intensive, except for maybe certain biological indices that require only moderate efforts.
These methods are also complex because they require trained biologists to adequately
collect the organisms, determine characteristics of the community, and effectively com-
pare the community to the reference conditions. Again, certain biological index methods
may be moderate in their level of complexity, depending on the variables and methods
included (Appendix Ac).
Performance Standards
It is a general assumption that that stream degradation reduces species diversity while
creating environments that select for a few tolerant species. In healthy streams, there are
generally moderate numbers of many species, including tolerant species that maintain an
ecological balance within the biological community. This difference in species assemblag-
es is the underlying premise for development of a biological index that can be used as a
tool for rapid stream assessments. Microbial monitoring tools using the periphyton
community have been developed for the states of Kentucky, Montana and Oklahoma
(Stevenson and Bahls, 1999), Idaho (Fore and Grafe, 2002) and the mid-Atlantic region
(Fore, 2003); many more are under development. What some of these biological indices
A Function-Based Framework » May 2012 198
-------
Chapter 10: Biology, Macrophytes
have found, however, is that the general assumption does not always occur in certain
regions and environmental conditions. This research highlights the need for species-spe-
cific, regional information from appropriate and adequate reference reaches to develop a
reliable biotic index for microbial communities.
An example of a biological index is the Periphyton Index of Biological Integrity (PIBI),
based on data collected in the Appalachian region (Hill et al., 2000). The PIBI included
algal taxa richness, relative abundances, chlorophyll and biomass (ash-free dry mass)
standing crops, and alkaline phosphatase activity. Functioning refers to streams with
good stream condition that have PIBI scores in the upper 25th percentile. Not Functioning
refers to streams with degraded condition that have PIBI scores in the lower 25th percen-
tile. Functioning-at-Risk streams have PIBI scores between these two percentiles.
TABLE 10.2 MICROBIAL COMMUNITY PERFORMANCE STANDARDS
MEASUREMENT
METHOD
Periphyton Index
of Biological
Integrity (PIBI;
Hill etal., 2000)
FUNCTIONING
>72
FUNCTIONING-
AT-RISK
61-71
NOT FUNCTIONING
<60
10.2 » PARAMETER: MACROPHYTES
Description
Macrophytes are the vascular plants, bryophytes and macroscopic algae that grow in
and near lotic environments (Hynes, 1970; Westlake, 1974). They are commonly divided
into subgroups based on their spatial growth form, including emergents (terrestrial to 1-m
depth), floating-leaved (1- to 3-m depth), submerged macrophytes (up to 10-m depth), and
free-floating (Sculthorpe, 1967; Eaton et al., 2005). When abundant, macrophytes can be
an important autochthonous energy source through primary production. During photo-
synthesis they transform CO2 absorbed from the air and water into organic carbon using
energy from sunlight. Oxygen is released into the air and water during the process
(Wetzel, 2001).
The influence of macrophyte communities on lotic ecosystems is dependent on their
abundance and the species present. Vegetative and root structures provide habitat for the
microbial community. Benthic macroinvertebrates and fish use macrophyte beds for feeding,
reproduction and shelter (Bowden et al., 2006; Janauer and Dokulil, 2006). Macrophyte
communities are also highly effective at nutrient cycling and organic matter processing
(Clarke, 2002). Most macrophytes are consumed during senesce and as detritus during
decomposition with secretion of dissolved organic carbon. Consumption of living tissue
is a minor carbon source (Wetzel, 2001). Macrophytes that are rooted to the substrate
provide channel stability and have been shown to improve surf ace-subsurface exchange
A Function-Based Framework » May 2012
199
-------
Chapter 10: Biology, Macrophytes
of gases, particularly O2 and CO2, and nutrients (White and Hendricks, 2000; Clarke, 2002).
Macrophytes are affected by many environmental factors that influence their abun-
dance and diversity. Hydrologic stability is one of the most important variables that
control establishment and growth (Westlake, 1974; Haslam, 1987). Rivers with low
gradients can have good community development in the littoral areas and backwaters
near the bank (Janauer and Dokulil, 2006). As macrophyte density increases, the commu-
nity can actually modify local flow conditions by decreasing streamflow velocity, pro-
tecting habitat and limiting scouring during storm events (Wetzel, 2001; Clarke, 2002).
Channel modifications that alter the natural flow regime and sediment dynamics, such as
vertical incision, channelization and impoundments, negatively impact macrophytes.
Studies have shown that macrophyte communities can experience loss of species, de-
clines in relative abundance and a shift to species that are more tolerant (Baattrup-Peders-
en and Riis, 1999; O'Hare et al., 2006). Another important physical requirement of
macrophytes is adequate light. In small forest streams, light is generally limited by the
riparian canopy, and macrophytes are not abundant. In larger rivers, light is attenuated
with increase in depth and turbidity; therefore, macrophytes are found only in shallow
waters near the streambanks. Macrophytes are most common in intermediate size rivers
where current is low, depths are shallow and there is plenty of sunlight exposure (West-
lake, 1974; Baattrup-Pedersen, 2006).
Macrophytes, like all lotic organisms, can be significantly affected by the stream
physicochemical conditions. They have preferences for specific temperature and pH
ranges, and available carbon and nutrient sources are required for growth and productiv-
ity. Carbon and nutrients are typically not limiting, however, due to the ability of most
macrophytes to absorb them through both vegetative structures and roots, and due to
constant source replenishment by the current (Bowden et al., 2006). When excess nutri-
ents and organic pollution are present, macrophyte communities react based on their
species-specific tolerances. Many studies have measured the effects of nutrient and
organic pollution on macrophyte assemblages, demonstrating species tolerances, shifts in
species composition and changes in abundance (Holmes et al., 1999; Schneider et al.,
2000; Haury et al., 2006; Janauer and Dokulil, 2006). Based on the sensitivity of macro-
phytes to changes in water quality, macrophytes can be good biological indicators of
stream condition and are closely linked to Level 4 functions.
Establishment of healthy macrophyte communities in restored channels should only
be considered in streams that are appropriate for population establishment, including
those with low gradients, shallow depths and adequate sunlight exposure. If the refer-
ence stream(s) have significant macrophyte development, then stream restoration tech-
niques should help create that habitat. Hydraulic methods that dampen large fluctuations
in discharge, including effective floodplain connectivity and attenuation of stream veloci-
ties during large storm events, will allow for establishment and reduce scouring of macro-
phyte beds. Maintaining a stable and healthy hyporheic zone especially benefits macro-
phytes with roots that depend on the substrate for nutrients, carbon and gas exchange.
Bed form diversity is important to create shallow habitats, and adequate sediment trans-
A Function-Based Framework » May 2012 200
-------
Chapter 10: Biology, Macrophytes
port prevents inundation of macrophyte beds. The presence of large woody debris and
in-stream structures can create habitat for macrophytes, diverting higher flows and creating
backwaters (Figure 10.2). Stream restoration practices that ensure channel stability and
improve water quality will also encourage establishment and growth of macrophytes that
in turn will provide dissolved oxygen, organic carbon and habitat for stream organisms.
Healthy macrophyte communities will be present in lotic environments when the follow-
ing conditions are met:
• Communities are present in the reference reach, as macrophytes requires certain flow
regimes controlled by stream gradient, adequate light and relatively shallow depths
that are not present in all stream types;
• Floodplain connectivity, which attenuates stormflows and creates a healthy hyporheic
zone benefiting plant roots;
• Relatively constant stream velocities, as less fluctuation in stream velocities allows for
macrophyte establishment;
• Bed form diversity, which provides available shallow habitat and helps to transport
sediment effectively to avoid inundation of macrophyte beds;
• Large woody debris, which creates backwater areas and provides shelter from high
flows for macrophyte establishment and growth; and
• Good water quality, which encourages species diversity and balanced population
dynamics that will perpetuate good water quality and provide essential stream habitat.
FIGURE 10.2 PHOTO OF MACROPHYTE DEVELOPMENT IN A RESTORED CHANNEL
Source: Reproduced with permission from Michael Baker Corporation
A Function-Based Framework » May 2012
201
-------
Chapter 10: Biology, Macrophytes
Measurement Method
Macrophytes should be evaluated within the growing season in order to better iden-
tify species and measure growth. Biomass measures should include the entire plant with
leaves, shoots and roots differentiated for several reasons. Some species have portions of
their communities that senesce quickly before reaching maturity. Other species may have
biomass concentrated within the root structure during certain times of their lifecycle
(Wetzel, 2001). Since productivity varies seasonally and with light, samples should be
taken at the same time of year and same location. Macrophytes respond to physicochemi-
cal conditions such as temperature and nutrient concentrations and flow conditions;
therefore, it is recommended that these parameters and perhaps others be measured
during appropriate macrophyte sampling intervals. Consult state sampling methodologies
for detailed instructions.
Macrophytes are commonly evaluated by field observations and by measurements of
standing crop collected from the stream and analyzed in the laboratory. Field observa-
tions can be made by visual assessment, with glass bottom buckets and other apparatuses
in deeper waters. Macrophyte samples are generally collected in a defined area, such as a
quadrant or transect, to determine quantitative measurements. Samples can be collected
by hand or using specialized equipment, such as a grapnel, in deeper waters. Detailed
methods for measuring macrophyte communities can be found in Westlake (1974),
Dawson, 2002, Eaton et al. (2005), and Bowden et al. (2006).
Three categories of measurement methods are presented below for macrophyte com-
munities. These categories are the same for the other biological communities discussed in
this chapter, including the direct methods for taxonomic and non-taxonomic measurements,
and the indirect method of the biological index measurement. The level of effort for all of
the measurement methods described below is considered intensive, except for certain
biological indices that may require only moderate efforts. These methods are also com-
plex because they require trained biologists to adequately collect the algae and plants,
determine characteristics of the community, and effectively compare the community to
the reference conditions. Again, certain biological index methods may be moderate in
their level of complexity, depending on the variables and methods included (Appendix Ac).
1. Taxonomic Measurements
Examples of taxonomic measurements include species composition, relative abundance
and taxa richness. Macrophyte species can typically be identified by visual observation
with taxonomic keys. Physical condition and density are additional measurements that
can be used to evaluate macrophyte populations.
2. Non-Taxonomic Measurements
Macrophyte biomass and primary productivity are the common methods used to
assess communities. Biomass can be determined using measurements of wet weight, dry
weight or ash-free dry mass. Chlorophyll a content can be quantified as a measure of
biomass, with knowledge of species composition and their typical concentrations. Popu-
A Function-Based Framework » May 2012 202
-------
Chapter 10: Biology, Macrophytes
lation productivity can be determined by collecting biomass data over time. This method
yields net productivity without corresponding measurements of loss to grazing, injury,
mortality and respiration. Primary productivity can be measured using similar methods
described for algae in the microbial communities section above.
3. Biological Indices
Macrophytes can be used as reliable biological indicators of water quality and stream
habitat because they are sessile, have established taxonomy, exhibit species diversity in
their ecological tolerances, and there are well-developed sampling techniques available.
Certain community characteristics should be kept in mind, however, when sampling to
evaluate stream condition. Macrophyte identification may be limited to the growing
season, there may be significant natural variation along a reach, and macrophytes may
experience a lag-time in recolonization after stream condition has improved, if resources
are limited upstream (Tremp and Kohler, 1995; Cronk and Fennessey, 2001).
Biological indices for macrophytes in lotic ecosystems have not yet been developed in
the United States. However, the use of macrophytes as biological indicators is historically
well established in Europe and is included in regulatory assessments of aquatic systems
for impacts and mitigation (Water Framework Directive; European Commission, 2000).
Three examples of commonly used biological indices are the Mean Trophic Rank index
(MTR; Holmes et al., 1999), the Macrophytical Biological Index for Rivers (IBMR; Haury
et al., 2006), and the Trophic Index of Macrophytes (TIM; Schneider et al., 2000). These
index methods focus on evaluating the effects of eutrophication in streams due to the
common occurrence of this impact. More integrative methods to assess river degradation
as a whole are described in Ferreira et al. (2002), Passauer et al. (2004), Schaumburg et al.
(2004), and Meilenger (2005). These methods use various ecological metrics for macro-
phytes that are similar for all organism biological indices, including methods that mea-
sure relative abundance, taxa richness, species diversity and distribution, and species
tolerances to environmental conditions. The recommended reach length of assessment is
typically 100m, and adequate reference reach (unimpacted stream) data should be col-
lected for comparative use with each biological index.
Performance Standards
Performance standards for macrophytes in rivers have not been derived in the United
States. The current European standards can be used as guidance for deriving these stan-
dards in the United States. These biological indices are based on plant species and their
determined tolerance values for ecological condition. These determinations must be made
for species present in the United States. The Mean Trophic Rank method (Holmes et al.,
1999) is provided in this publication as an example biological index that evaluates the
effects of excess nutrients in rivers, a common problem in most streams in our country
(Table 10.3). This index uses calculated variables, including Species Trophic Rank (STR)
with values representing species tolerance between 1 (eutrophic conditions) and 10
(unenriched waters), and Species Cover Value (SCV) as a percentage ranked between 1 (<
A Function-Based Framework » May 2012 203
-------
Chapter 10: Biology, Macroinvertebrate Communities
1%) and 9 (> 75%) to determine an overall MTR Score. Streams in the Functioning
category would not require nutrient reductions. Functioning-at-Risk would require
monitoring of nutrient inputs and nutrient reduction plans. Not Functioning would
require reductions in nutrient inputs within a reach. Another biological index presented
as an example is one that assesses overall stream condition compared to reference condi-
tions, called the Reference Index (RI; Meilenger, 2005). Streams are divided into catego-
ries based on a classification system. The example given in Table 10.3 is for river type TN;
which are medium-sized lowland rivers. The results provide an ecological status classifi-
cation based on the deviation in macrophyte composition and abundance from reference
conditions. Streams in the Functioning category would be classified as high or good;
Functioning-at-Risk would be classified as moderate, and Not Functioning would be
classified as poor or bad.
TABLE 10.3 MACROPHYTE BIOLOGIC INDICES PERFORMANCE STANDARDS
MEASUREMENT
METHOD
Mean Trophic
Rank (MTR);
Holmes etal. 1999
Reference Index
(RI)
FUNCTIONING
>5
-50 to 100
FUNCTIONING-
AT-RISK
25-65
-70 to -50
NOT FUNCTIONING
<25
<-70
10.3 » PARAMETER: MACROINVERTEBRATE COMMUNITIES
Description
The macroinvertebrate communities of lotic systems are commonly composed of
mussels (mollusk), crayfish (crustaceans), worms (annelids) and insects (arthropods).
Aquatic insects that live along the substrate are referred to as benthic macroinvertebrates,
and this group is the most commonly evaluated in stream systems due to their higher
diversity and abundance across stream types. Benthic macroinvertebrates generally have
an aquatic immature stage and a terrestrial adult stage. They inhabit many different areas
of a stream (Figure 10.3), and location often depends on their primary feeding mecha-
nism. Functional feeding groups are often used to categorize aquatic insects and include
predators, collectors, scrapers and shredders (Cummins, 1973; Voshell, 2002). A collector
may feed by gathering detritus from the stream bed or by filtering detritus out of the
water column, while a scraper scrapes periphyton off of the substrate. Shredders feed by
shredding organic material, such as leaves, and can be found in leaf packs that accumulate
along banks and woody debris in the channel.
Macroinvertebrate lifecycle demands and processing can have important influences on
nutrient and carbon cycles and movement of energy in and around lotic systems. They
are an important link in transferring energy up the aquatic food chain as an intermediate
A Function-Based Framework » May 2012
204
-------
Chapter 10: Biology, Macroinvertebrate Communities
trophic level. Benthic macroinvertebrates feed on periphyton, small bits of organic mate-
rial, and other organisms and are in turn fed on by fish and terrestrial insectivores (Jack-
son and Resh, 1989; Wallace and Webster, 1996). Energy flows between terrestrial and
aquatic environments, and between allochthonous and autochthonous sources (e.g., the
export of autochthonous energy and a return of allochthonous energy contributed by the
terrestrial system to the stream channel, and then a flow of energy back to the terrestrial
system with the emergence of the adult aquatic insects).
Macroinvertebrates are influenced by water quality, habitat availability and food
resources. Benthic macroinvertebrates have a range of sensitivities to changes in organic
pollutants, sediments and toxicants, as well as habitat conditions. Macroinvertebrates are
good indicators of water quality and stream condition. There are several reasons for this,
including: 1) they have relatively short lifecycles that span multiple seasons; 2) species
have different tolerances to water quality and stream condition; and 3) they are less
mobile than fish and, therefore, cannot easily escape local perturbations (Kuehne, 1962;
Bartsch and Ingram, 1966; Wilhm and Dorris, 1968; Warren, 1971; Cairns and Pratt,
1993). The sufficient availability of food resources, including plankton, periphyton and
dissolved and particulate organic matter, can promote benthic macroinvertebrate produc-
tivity (Richardson, 1993).
Benthic macroinvertebrate communities can benefit from many stream restoration
techniques, even in highly degraded systems. Floodplain connectivity and design of an
appropriate bankfull channel reduce the impacts of large storm events on habitats and
excessive scouring that removes food resources. Organic carbon can be carried from the
floodplain to the stream during storm events, and fine sediment can be deposited on the
floodplain instead of inundating stream habitats. Benthic macroinvertebrates are associ-
ated with the hyporheic zone, using it as physical habitat, as well as feeding on periphy-
ton established at the groundwater-surface water interface where dissolved organic
carbon is exchanged. Any stream restoration practice that increases available habitat will
enhance communities. Bed form diversity and in-stream structures provide both habitat
and enhance stream stability. Structures that are constructed using large woody debris,
root wads and other woody material are particularly beneficial to macroinvertebrates
because they provide resting and escape cover, increase surface area for feeding, capture
additional organic material, and increase retention time of organic material that supports
many macrobenthic invertebrate feeding groups. The addition of woody material has
been shown to improve density and species diversity of macroinvertebrates (Gerhard and
Reich, 2000). Restoration of the riparian plant community is usually a component of
stream restoration projects and will significantly benefit aquatic macroinvertebrates by
providing thermal regulations, as well as contributions of woody debris and leaf litter to
support food chains.
A Function-Based Framework » May 2012 205
-------
Chapter 10: Biology, Macroinvertebrate Communities
A healthy functioning macroinvertebrate community occurs when the following condi-
tions are present:
• Floodplain connectivity and bankfull channel, which dissipate energy of large storm
events to prevent excessive scouring of substrate, provide access to organic carbon
sources available on the floodplain and prevent sediment inundation of substrate habitat;
• Healthy hyporheic zones, which provide habitat for macroinvertebrates and facilitate
exchange of dissolved constituents for healthy periphyton communities, a valuable
food resource;
• Bed form diversity and complexity, create diverse habitats for feeding and reproduc-
tion, dissipate stormflow energy, provide opportunities for organic carbon storage and
retention, provide substrates such as large woody debris, and provide scour holes and
offer shelter;
• Channel stability, which prevents sediment inundation of habitat and the detrimental
effects of turbidity on filter feeders; and
• Riparian community, which provides allochthonous carbon inputs for food resources;
provides shade for cooler temperatures and provides vegetative roots for available habitat.
FIGURE 10.3 MACROINVERTEBRATES OCCUR IN A VARIETY OF HABITATS WITHIN THE
STREAM CHANNEL, INCLUDING THE RIFFLES AND POOLS CREATED BYTHE ROCKS AND
WOODY DEBRIS IN THIS MOUNTAIN STREAM.
Source: Reproduced with permission from Stream Mechanics
A Function-Based Framework » May 2012
206
-------
Chapter 10: Biology, Macroinvertebrate Communities
Measurement Methods
Benthic macroinvertebrates sampling is mostly appropriate for perennial channels due
to the physical size of the organisms and the higher diversity found in running waters.
Assessments on the recovery of benthic macroinvertebrate populations based on refer-
ence stream communities are recommended. For the most rapid recolonization after
restoration, reference conditions should ideally be present upstream of the restored reach.
The methods used to collect macroinvertebrates are fairly consistent across monitoring
protocols. Visual observation along with various types of nets and sieves can be utilized
in the different habitats to capture benthic species. Habitats include riffles, pools, leaf
packs and woody debris, sediments, and macrophyte beds. Macroinvertebrate samples
must be collected in proportion to the relative habitat abundance, and organisms must be
collected in proportion to the species abundance in order to get a sample that truly
represents the community structure. There are many assessment methods and protocols
developed throughout the United States for benthic macroinvertebrates, including the
EPA Rapid Bioassessment Protocol (RPB) method (Barbour et al., 1999), the EPA Environ-
mental Monitoring and Assessment Program (EMAP) methods (Klemm et al., 2000), or
the North Carolina Department of Natural Resources Division of Water Quality's Benthic
Macroinvertebrate Monitoring Protocols (NCDENR, 2006), to name a few. In general,
most macroinvertebrate sampling protocols involve a multi-habitat approach since macro-
invertebrates occupy diverse habitats within the stream channel.
The three categories of measurement methods associated with biological macroinver-
tebrate communities are presented below, including the direct methods for taxonomic
and non-taxonomic measurements, as well as the indirect method of the biological index
measurement. The level of effort is considered intensive, except for certain biological
indices that may require only moderate efforts. These methods are also complex because
they require trained biologists to adequately collect the macroinvertebrates from different
habitats, to determine characteristics of the community, and to effectively compare the
community to reference condition assemblages. Again, certain biological index methods
may be moderate in their level of complexity, depending on the variables and methods
included (Appendix Ac).
1. Taxonomic Measurements
Benthic macroinvertebrate samples can be evaluated for taxonomic measures such as
species composition, relative abundance and taxa richness. Mandaville (2002) provides an
extensive review of population metrics that are commonly used to access macroinverte-
brate populations. Species identification is performed using the many readily available
taxonomic keys, including general keys (e.g., Peckarsky, 1990; Merritt and Cummins, 1996;
Smith, 2001; Thorp et al., 2009). State or regional keys should be sought to limit the species
to be considered and greatly aid the identification of macroinvertebrate samples. Often,
abbreviated samples will just focus on three orders that are the most sensitive to stream
condition: Ephemeroptera (mayflies), Plecoptera (stoneflies) and Trichoptera (caddisflies).
Sampling and identification of these three orders is referred to as an EPT assessment.
A Function-Based Framework » May 2012 207
-------
Chapter 10: Biology, Macroinvertebrate Communities
2. Non-Taxonomic Measurements
Measurements of biomass and secondary production allow for an assessment of how
available energy is being utilized for macroinvertebrate growth. Benke (1984, 2010)
provides an excellent discussion of the biological parameters that contribute to macroben-
thic secondary production. There are many approaches to making secondary production
measurements, depending on the application of the data (Benke and Huryn, 2010).
Secondary production involves the measure of biomass over some period of time. Often
these studies look at the production by a single age group or cohort. One sampling meth-
od that is often used for this purpose is the emergence trap. This is a trap placed over the
stream that captures adult insects as they leave the water and can provide data for esti-
mating abundance, biomass and production. Consideration should be given to trap
placement in order to take a representative sample (Malison et al., 2010). While the
emergence trap is relatively easy to use for this purpose, secondary production can also
be determined at the aquatic life stage using established collection methods, quantifying
biomass and establishing how this changes over a time (Jaynie et al., 2007).
3. Biological Indices
Benthic macroinvertebrates are widely used as a monitoring tool by many water
resource agencies (Southerland and Stribling, 1995; USEPA, 2002). The change in popula-
tions and species assemblage composition over time can also reveal if the change has
been positive or negative. Species have varying tolerances to pollutants, and a biologist
experienced at identifying benthic macroinvertebrates should be able to look at a popula-
tion sample and quickly determine whether or not it is from a stressed aquatic system.
Macroinvertebrate biotic indices generally include assessments of taxonomic and non-
taxonomic metrics and include information on tolerances to stream condition and habitat
measures. Many state agencies have developed biotic indices that are based on these metrics
and data collected in various stream types, including reference reaches in different regions.
Performance Standards
Thresholds for determining if a stream is Functioning based on the macroinvertebrate
community must be considered with stream type and the expected community type in
mind. In general, it is always best to compare the condition of a project site with observa-
tions at stable reference streams. Performance standards for taxonomic and non-taxonom-
ic measurements have generally not been developed. Biotic indices developed for specific
stream types and regions that combine these measures with stream physicochemical and
habitat conditions can, however, be used as performance standards. Several examples of
biotic indices are listed in Table 10.4. Streams that fall into the Not Functioning category
would most likely also have very low taxa richness and mostly very tolerant taxa, such as
aquatic worms and snails. Engel and Voshell (2002) developed a quantitative multimetric
index for volunteers with the Virginia Save Our Streams program to use, and found that
it agreed very closely (96%) with the determinations made by professionals. In this study
they found 15 candidate macrobenthic-based metrics that exhibited statistical properties
A Function-Based Framework » May 2012 208
-------
Chapter 10: Biology, Fish Communities
that would make them good measures of water quality. The process used in this study
would be beneficial to use for developing a regionally specific biotic index if one does not
exist. While these performance standards can be used anywhere, it is recommended that
they be evaluated against a sample from a reference stream to ensure they provide the
proper measure of performance.
TABLE 10.4 MACROINVERTEBRATE PERFORMANCE STANDARDS
MEASUREMENT
METHOD
Hilsenhoff Biotic
Index (HBI)
(Hilsenhoff, 1988)
WVSCI (Gerritsen
etal., 2000;
WVDEP)
Virginia Stream
Condition Index
(Burton and
Gerritsen, 2003)
SOS Multimetric
Index (Engel and
Voshell, 2002)
FUNCTIONING
0.00-4.25
Excellent to Very
Good
68-100
Very Good to Good
61-100
Exceptional to
Similarto Ref.
7-12
Acceptable
FUNCTIONING-AT-
RISK
4.26-5.75
Good to Fair
45-61
Gray Area to Fair
40-60
Impaired Tier 1
N/A
NOT FUNCTIONING
5.76-10.00
Fairly Poor to Very
Poor
0-45
Poor to Very Poor
0-40
Impaired Tierl & 2
0-6
Unacceptable
10.4 » PARAMETER: FISH COMMUNITIES
Description
Fish are the most ubiquitous vertebrate species found in rivers and streams. Fish are
the top aquatic predators in most lotic systems and are utilized for food by many terrestrial
species. Stream fishes have many adaptations for living in high velocity environments.
They can use low-velocity microhabitats like pools, downstream sides of cover elements,
or areas under and between substrate. Stream fishes have bodies that are fusiform and
streamlined to reduce drag in high velocity, or they are adapted to living on the bottom
with large pectoral fins that are aligned so that flow pushes the fish downward. Fish are
often specialized feeders with anatomical adaptations for feeding on the bottom, scrap-
ing periphyton, picking macroinvertebrates off of rocks, or capturing other fishes. They
have adapted reproductive approaches that protect their eggs and young, such as spawn-
ing on the undersides of exposed rocks, building clean pebble bounds in which to scatter
their eggs, or burying the eggs in clean, well aerated gravel beds (Balon, 1975).
Fish communities include herbivores, insectivores, detritivores and piscivores. They
serve as important links in aquatic food chains because they move the energy captured
from lower trophic levels up to higher-level predators, such as terrestrial animals. Just as
A Function-Based Framework » May 2012
209
-------
Chapter 10: Biology, Fish Communities
with emerging macroinvertebrates, fish also act as the link for moving energy produced
or captured in the aquatic environment to the terrestrial environment. One of the most
dramatic examples of the importance of fish to aquatic food chains is the influence of
anadromous salmon. These fish spend several years at sea feeding and growing and then
move into rivers and streams to spawn. After spawning, they die, which provides an influx
of nutrients during decomposition. This leads to an increase in food chain productivity,
which in turn supports the young salmon as they grow to a size when they return to the
ocean for the process to begin again. As top predators in stream systems, fish populations
have been shown to affect the structure of prey populations, including the movement of
prey from one habitat patch to another (Sih and Wooster, 1994), as well as the structure
of the fish community itself through piscivory (Jackson et al., 2001). Given the impor-
tance of fish in structuring the populations of their food resources, they play a significant
role in the population dynamics, nutrient cycling and energy flow in lotic ecosystems.
The ability of fish populations to fulfill their life history requirements normally de-
pends on streamflow, water quality and habitat availability. Adequate flow in rivers and
streams must be maintained to allow fish movement and survival. Impoundment struc-
tures can block fish passage and hold streamflow back to levels that will not support fish.
Water withdrawals for human activities and consumption may prevent adequate flow
during certain seasons where water tables are already low due to normal hydrology
(Wootten, 1992). Changes in Physicochemical parameters can have a significant impact
on fish. Fish can be highly sensitive to the amount of dissolved oxygen in the water
column. When the oxygen levels drop below a certain threshold, this can have dramatic
effects on fish populations and "fish kills" result (Hynes, 1960). Stream temperature not
only affects fish metabolism between seasons, it also determines their distribution
(Hynes, 1970). Warm-water streams and cold-water streams are distinguished as fish
habitat based on the presence of certain fish species (Moyle and Cech, 1982). When
restoring the functional ecology of a stream, the goal is typically to improve overall fish
habitat. Good habitat includes creating riffle, run, pool and glide bed forms, as well as
providing diverse cover elements within the channel. Diverse habitat will support differ-
ent stages of a fish's life cycle and/or different species of fish over a varying spatial and
temporal scale (Rohde et al., 1994). Diverse habitat also produces diverse food sources for
fish. This may include patches within a stream that support algae or macrophytes for
herbivores; riffles or woody debris that supports various benthic macroinvertebrates; or
deep pools where piscivorous predators may ambush smaller fish. Habitat diversity is
generally correlated with diversity in fish communities within streams.
Fish are often the primary connection between a water course and the human popula-
tion that utilizes it. The devotion that these resources inspire is demonstrated by the
creation of resource-based groups like BASS and Trout Unlimited. These groups invest
significant resources in the preservation of habitats that supports the population in which
they are interested. Because their efforts are directed at habitat preservation and restora-
tion, the result often benefits all species using the habitat. This scenario demonstrates the
importance that man places on aquatic resources supporting fisheries. It is for this reason
A Function-Based Framework » May 2012 210
-------
Chapter 10: Biology, Fish Communities
that the benefit of restoration projects on fish populations is important and should be
considered as a potential parameter to be evaluated. Fish are good indicators of both
short-term and long-term water quality and stream condition because they are relatively
long-lived, mobile and many have a lifecycle that requires high water quality. Assessing
stream fish populations provides important information for understanding the function-
ing of the biological community, for evaluating biological integrity and for protecting
surface water resource quality (Barbour et al., 1999).
There are many stream restoration practices benefitting fish populations within all
four underlying levels of the Stream Functions Pyramid that are similar for other biologi-
cal communities. Hydrology and flow dynamics are very important for fish populations,
particularly considering the essential requirement of adequate flow conditions through-
out the seasons. Upstream impoundments and water withdrawals should be addressed
prior to design to ensure continuous streamflow. If these upstream flow conditions
cannot be addressed, then restoration of fish habitat may be futile. Assessment of refer-
ence condition is an important tool for determining if fish are present in the stream type,
as well as size that will be restored. Upstream populations will also determine re-estab-
lishment of fish communities. If there is no upstream fish population, stocking may be
required to introduce the fish into the newly created habitat. Species of special concern,
including any threatened or endangered species designated by federal and state agencies,
should always be considered first when designing habitat features of a restored stream
channel. Hydraulic parameters, including floodplain connectivity and the provision of a
bankfull channel, are effective at sustaining fish populations along with other biological
communities. A healthy hyporheic zone and substrates that support prey populations will
help sustain fish with food resources. Fish habitat created by in-stream structures, large
woody debris, macrophyte beds and bed form diversity will allow for feeding, shelter
and reproduction, including deep pools and scour holes (Figure 10.4). Established riparian
buffers provide shade for temperature regulation and allochthonous inputs to sustain prey
populations and the large woody debris. Good water quality is important, especially
maintenance of dissolved oxygen levels that result from structures and flow dynamics
providing turbulence for oxygen entrainment, and from habitats that provide primary
production of algae and macrophytes.
A healthy, functioning fish community occurs when the following conditions are present:
• Continuous upstream streamflow sources, as removal of impoundments and excessive
water consumption for human activities will provide adequate streamflow throughout
the year;
• Floodplain connectivity and bankfull channel, dissipate energy of large storm events
to prevent excessive scouring of substrates used for reproduction (pools), and prevent
sediment inundation of substrate habitat;
• Healthy hyporheic zones, which provide habitat for food resources;
• Bed form diversity and in-stream structures, which create diverse habitats for feeding
and reproduction, dissipate stormflow energy; provides opportunities for organic
A Function-Based Framework » May 2012 211
-------
Chapter 10: Biology, Fish Communities
carbon storage and retention, provide substrates such as large woody debris, and
provide scour pools for reproduction, feeding and shelter;
Channel stability, which prevents sediment inundation of habitat and excessive
turbidity that is contributed from channel erosion;
Riparian community, which provides allochthonous carbon inputs for food resources,
provides shade for cooler temperatures and provides vegetative roots for available
habitat; and
Adequate dissolved oxygen, which is required for fish survival and health.
FIGURE 10.4 FISH HABITAT IN A SCOUR POOL CREATED
BY AN IN-STREAM STRUCTURE, REFERRED TO AS A J-HOOK.
Source: Reproduced with permission from Michael Baker Corporation
Measurement Method
Fisheries resources can be sampled using a variety of
approaches, and the sampling methodology selected
should be chosen to provide quantifiable measurements
for the parameter addressed (Bonar et al., 2009). The
USEPA's RBP (Barbour et al., 1999) recommends using
electrofishing to collect samples, a common method
used by most state fishery departments and fisheries
investigators to evaluate fish populations in designated
reaches (Carle and Strub, 1978; Zippin, 1956). Snorkel-
ing the study reach and recording observed species is a
less intrusive method that some have used. This has
been used as an alternative to electrofishing (Thurow and Schill, 1996; Mullner et al.,
1998) for estimating abundance and population size structure. The National Park Service,
in conjunction with George Mason University, compiled an Ecological Assessment Meth-
ods Database (2010). The database was originally created to provide park managers with
a source for identifying and selecting assessment methods for various watershed manage-
ment practices, including methods for assessing fisheries and their habitat. The database
can be accessed at http://assessmentmethods.nbii.gov.
When evaluating fish communities, there are several factors that must be considered.
Fish movement (passage) within the stream, and upstream water quality issues should be
considered when interpreting data. Sample design often involves comparisons between
restored areas and unrestored areas on the same stream, and should include pre- and
post-restoration sampling.
The three categories of measurement methods associated with biological fish commu-
nities are presented below including the direct methods for taxonomic and non-taxonom-
ic measurements, as well as the indirect method of the biological index measurement.
The level of effort is considered intensive, except for certain biological indices that may
require only moderate efforts. These methods are also complex because they require
A Function-Based Framework » May 2012
212
-------
Chapter 10: Biology, Fish Communities
trained biologists to adequately collect the macroinvertebrates from different habitats,
determine characteristics of the community, and effectively compare the community to
reference condition assemblages. Again, certain biological index methods may be moderate
in their level of complexity, depending on the variables and methods included (Appendix Ac).
1. Taxonomic Measurements
Once a fish population sample is obtained, individuals should be identified to species
and enumerated. Fish sample data can be expressed in species composition, relative
abundance, species richness (or other taxon), percent similarity between sites, Simpson's
Diversity Index (Simpson, 1949), or other similar indexes and metrics.
2. Non-Taxonomic Measurements
Data on population size or biomass will require length and weight data of fish col-
lected within a sample, as well as a good measure of the area sampled. The growth rate,
or change in biomass of fish over time, is an estimate of productivity. Growth rate data
requires aging fish or estimating age and is a more complicated process than most restora-
tion monitoring programs will undertake; but this process is still a good measure of fish
community productivity. Details of both taxonomic and non-taxonomic methods can be
found in Hauer and Lamberti (2006), Methods in Stream Ecology.
3. Biological Index
As with other taxa, fish population quality can also be expressed in an Index of Biotic
Integrity. Karr et al. (1986) recommended 12 measures of fish assemblages that fall into
three broad catagories: species composition, trophic composition, and fish abundance and
condition. This methodology has been applied to evaluations of fish populations, and it
has been adjusted by state and regional biologist to reflect regional stream conditions.
Angermeier and Karr (1986) used an IBI for stream-fish communities to evaluate water
and habitat quality. Roth et al. (1996) used a fish population IBI to demonstrate that
habitat and fish assemblage quality was highly correlated.
Performance Standard
For the best results, performance standards should be based on data collected from
reference reaches upstream of the restoration reach. A reference condition can be estab-
lished using the upstream reference reach and/or other reference streams. Multiple sam-
ples that account for spatial and temporal variability should be collected before setting
these standards. If species to be evaluated include populations that support a fishery,
evaluators should consult state fishery agencies to see if they have already established the
range of variation that these populations typically exhibit. This information can then
help guide empirically establishing performance standards.
Performance standards for taxonomic and non-taxonomic measurements have gener-
ally not been developed. However, biotic indices developed for specific stream types, and
regions that combine these measures with stream physicochemical and habitat conditions
A Function-Based Framework » May 2012 213
-------
Chapter 10: Biology, Landscape Connectivity
can be used as performance standards. Several examples of biotic indices are listed in
Table 10.5. Streams that fall into the Functioning category have high species diversity and
relative abundance, which indicates good stream habitat. The Not Functioning category
would most likely have very low taxa richness and mostly very tolerant taxa that indi-
cates poor stream habitat.
TABLE 10.5 FISH COMMUNITY PERFORMANCE STANDARDS
MEASUREMENT
METHOD
Mid-Atlantic
Highlands IBI
(McCormick et
al., 2001)
Mid-Western Fish
Community IBI
(Karretal., 1986)
FUNCTIONING
IBI > 72
Good to Excellent
48-60
Good to Excellent
FUNCTIONING-AT-
RISK
IBI = 56 to 71
Fair
40-44
Fair
NOT FUNCTIONING
IBI < 56
Poor
0-34
Poor to No Fish
10.5 » PARAMETER: LANDSCAPE CONNECTIVITY
Description
The importance of using a holistic landscape perspective for understanding stream
ecosystem structure and function is well established. Recognition of the connection
between the stream and surrounding terrestrial ecosystems was fundamental to the
development of stream ecosystem theory (Hynes, 1975; Minshall et al.; 1985). The
landscape connectivity concept is defined as "the degree to which the landscape (physical
structure) facilitates or impedes movement (organism behavior) among resource patches"
(Taylor et al.; 1993). It includes both structural and functional aspects of the landscape.
Structural aspects are the physical relationships among habitat patches and the distance
between them. The dimensions of a stream riparian buffer corridor are an example of
structural connectivity. Functional aspects are what affect the movement behavior of
organisms through the landscape. Most landscape connectivity evaluations include only
structural assessment, which may not be at the appropriate spatial scale nor adequate to
prevent loss of essential habitat. There is a critical threshold of landscape connectivity
that must be maintained in order for the species of interest to persist (With et al.; 1997).
In stream restoration projects, landscape connectivity represents the ability of a target
aquatic or riparian species to move between habitats. Fish migrate upstream and down-
stream to feed and reproduce. Benthic macroinvertebrates migrate not only upstream and
downstream, but also across the land-water interface between the larval and adult stages.
Some benthic macroinvertebrate adults may even require different terrestrial landscape
habitats surrounding water to persist. Stream restoration projects can contribute to
landscape connectivity using practices at all levels of the Stream Functions Pyramid.
A Function-Based Framework » May 2012
214
-------
Chapter 10: Biology, Landscape Connectivity
Hydrologic parameters create that link between landscape and lotic system through
exchange of water resources, including surface runoff and groundwater inputs. Floodplain
connectivity and establishment of riparian buffers are other important land-water con-
nections for organism (plant and animal) movement between habitat patches. Microbial
species, plant seeds and spores, and vertebrate eggs can be deposited in terrestrial habitats
for migration to the lotic system during high-flow events. Any in-stream structure that
promotes habitat diversity and allows passage of animal species or establishment of
microbial and plant species is essential for landscape connectivity. Stream stability will
protect both aquatic and terrestrial habitats and allow for movement of species. Good
water quality and resource availability (carbon and nutrients) are essential for healthy
biota that will move between habitats and persist through landscape connectivity.
Landscape connectivity is enhanced when the following conditions are present:
• Long reaches of restoration connected to other high-quality reaches, which provide
healthy stream corridors;
• Surface runoff and groundwater inputs, which maintain the connection between land
and water habitats and their shared resources;
• Floodplain connectivity and established riparian buffers, which maintain the connec-
tion between land and water habitats and their shared resources, and allow movement
of species between habitats during life cycle;
• In-stream structures, which can promote organism passage and habitat and substrate
for stream organisms;
• Stream stability, which protects aquatic and terrestrial habitats; and
• Good water quality and resource availability, provide the environmental conditions
for biological movement and species persistence.
Measurement Method
Measurement methods used to assess landscape connectivity are all direct measures
that require intensive level of effort due to the spatial aspects associated with the data
required. The methods are all considered complex due to the tools required for assess-
ment, e.g., GIS, GPS and models, as well as the expertise required for data collection and
analyses. There are three measurement methods described below.
1. Spatial Analysis
In order to measure overall landscape connectivity effectively, both structural and
functional pieces must be included. Structural landscape connectivity can be measured
using linear features on the landscape, which are commonly measured with current
spatial analysis technologies such as GIS. The length of a riparian corridor or forested
wetland patch near a stream would be an example of a linear feature.
A Function-Based Framework » May 2012 215
-------
Chapter 10: Biology, Landscape Connectivity
2. Species Tracking
Functional landscape connectivity measurements are not as readily available because
they are specific to individual species or species groups with similar behaviors. Taylor
(1993) details species parameters that can provide information on species movement in
response to the landscape structure, including movement rates, dispersal range, mortality
during dispersal, and boundary interactions. Species movement is not easy to measure,
but knowledge of species behavior can be gathered from the literature and from on-the-
ground tracking and satellite GPS technologies. In streams, invertebrates and vertebrates
can be tagged for monitoring. Currently there are tracking products available for larger
aquatic species (e.g., Pacific salmon; Eiler, 1995), but smaller species and canopy cover
issues have not advanced. Consultation with biologists who are familiar with the species
of interest, their habitat requirements throughout their life cycle, and their behaviors can
help with landscape connectivity measurements.
3. Habitat Models
There are also various habitat models described in the literature that have been devel-
oped to provide landscape connectivity assessments specifically (With et al., 1997). There
are also CIS-based models that have been developed to help with habitat assessments
that can be found at the following websites:
Circuitscape: www.circuitscape.org/Circuitscape/Welcome.html
Conefor Sensinode: www.conefor.org
Funconn: www.nrel.colostate.edu/projects/starmap/funconnjndex.htm
Pathmatrix: cmpg. unibe. ch/software/pathmatrix
Performance Standards
There are no performance standards developed for landscape connectivity at this time.
The landscape matrix should be included in stream restoration planning, however, in
order for the project to provide the greatest biological benefit. Although this matrix most
often extends beyond the boundary (and scope) of stream projects, it is important to keep
it in mind as a focal point during the planning process in order to establish the landscape
connectivity needed for a healthy biological community. Landscape connectivity also
relates to proper site selection for a stream restoration project. In order to see the most
improvement in the other Biology parameters listed above, it is critical that the restora-
tion reach be "connected" with a high-quality upstream reference reach. The restoration
reach, in turn, begins to provide the necessary conditions for future downstream restora-
tion efforts to continue progress towards landscape connectivity for species selected
within the stream. Linking restoration projects together is a good way to increase land-
scape connectivity and work towards watershed scale restoration. This approach pro-
vides greater functional lift than restoring discrete stream reaches that are spread out
across the watershed.
A Function-Based Framework » May 2012 216
-------
Chapter 11
Application of the Stream Functions Pyramid
This chapter provides three different examples of how the Stream Functions Pyramid
can be applied. These applications include creating function-based goals and objectives,
developing stream assessment methods, and establishing stream mitigation debit and
credit determination methods.
Goal setting is critical to the success of a project because it communicates why the
project is being done and sets expectations on how success will be measured. The goal-
setting section provides several examples of goals that will improve stream functions
when achieved. The assessment and mitigation sections provide a broad overview of how
the Pyramid can be applied. It does not provide a "cookbook" approach to developing a
functional assessment methodology or stream mitigation Standard Operating Procedures
(SOPs). Rather, the examples and templates provided below are intended to provide a
broad-level framework. Scientists and managers may choose to create more specific or
quantitative functional assessments and debit/credit determination methods based on the
examples provided in this chapter.
11.1 » ADDING PARAMETERS, MEASUREMENTS AND PERFORMANCE
STANDARDS
The existing Stream Functions Pyramid Framework includes a wide range of function-
based parameters that are applicable for a wide range of environmental settings. How-
ever, users may need to add a function-based parameter based on a unique project or
assessment goal. This is most likely to occur at the Biology Level because not all forms of
aquatic and riparian life are included, e.g., mussels and amphibians. To add a function-
based parameter, users should follow the selection criteria outlined in Chapter 4.
11.2 » DEVELOPING GOALS AND OBJECTIVES
Developing goals and objectives is important for projects of all sizes. Well-articulated
goals and objectives establish a foundation for project success. Vague, too broad, or poorly
articulated goals and objectives often lead to project failure (worst case) and misunder-
standings at best. The terms goals and objectives are often used interchangeably; how-
ever, there is a difference. Goals are statements about why the project or effort is needed.
They are general intentions and often cannot be validated. Objectives are more specific.
They help explain how the project will be completed. They are tangible and can be
validated, typically by the performance standard.
A Function-Based Framework » May 2012
217
-------
Chapter 11: Application of the Stream Functions Pyramid
Even with this differentiation, it can be challenging to develop well-formulated goals
and objectives. Part of this difficulty relates to the scale and type of effort that is being
undertaken. For example, watershed management plans require goals and objectives at a
broad scale, i.e., to cover a large watershed. Stream restoration projects require goals and
objectives that are typically formulated at a
Goals are statements about reacn scale and after some type of assess-
Why the project Or effort is m6^ haS been comPleted to determine the
problem, i.e., what runction(s) needs to be
needed. They are general restored. This can be an iterative process as
intentions and Often Cannot the project team tests the restoration needs
be validated. Objectives are a§ainst Pr°iect and watershed constraints.
Regulatory and non-regulatory programs
more specific. They help also have goals and ob]-ectiveS; but they may
explain how the project not be tied to a specific watershed or reach.
Will be Completed. They For example, Trout Unlimited, a non-regula-
are tangible and can be tory orf mza'ion' ^ broad goals tc?m-
prove the quality of trout streams, wherever
validated, typically by the trout streams exist. The Clean Water Act
performance Standard. (FWPCA, 1972) has an overall goal for all
waterways to be fishable and swimmable.
Section 303 of the CWA includes provisions to have all streams, and rivers support the
designated uses identified in their water quality standards (FWPCA, 1972). No net loss of
wetland resources is a goal of the Section 404 of the CWA program and the fundamental
objective of compensatory mitigation in the regulatory program is to offset environmen-
tal losses resulting from unavoidable impacts [33.C.F.R. § 332.3(a)(l)_/40 C.F.R. §
230.93(a)(l)].
Many existing stream SOPs associated with the CWA Section 404 program include
references to restoring stream dimension, pattern and profile as a way to acquire restora-
tion credits. This has resulted in many stream mitigation plans being created that state
the goal of a project is to restore dimension, pattern, and profile, rather than stating goals
that provide some type of functional lift to offset permitted losses and better align with
the fundamental objective of the CWA Section 404 regulatory program.
The Stream Functions Pyramid can be used to help prepare better goals and objectives
for watershed management plans, regulatory and non-regulatory programs, and stream
restoration projects. Simply stated, the Pyramid can help link goals and objectives to
stream functions. For example, the Pyramid can be used to help articulate goals that
relate to the improvement or assessment of stream functions or even function-based
parameters. The goal should relate to the primary function(s) of interest, e.g., life history
of some type of aquatic life. This information is provided on the Pyramid Overview and
the Pyramid Functions and Parameters. Objectives should help explain how the function-
al improvement will occur. Objectives can also be used to identify the supporting func-
tions needed to meet the goal. The Pyramid Functions and Parameters, Measurement
A Function-Based Framework » May 2012 218
-------
Chapter 11: Application of the Stream Functions Pyramid
Methods and Performance Standards are all helpful in formulating objectives. These
figures and tables are provided in Appendix A. Other sources for developing stream
restoration-related goals and objectives include the NRCS Stream Restoration Design
Manual, Part 654, Chapter 2 (USDA NRCS 2007) and the USAGE Technical Note, Ecosys-
tem Restoration Objectives and Metrics (McKay et al., 2012).
Developing goals and objectives requires an understanding of how to "enter" the
Pyramid, i.e. how to start using the Pyramid Framework. Examples for watershed man-
agement plans, regulatory/non-regulatory programs and project designs are provided below.
Watershed Management Plans
Watershed management plans typically include two major components, an inventory
of water resource problems, followed by options/recommendations for improvement.
These improvement options may include preservation, restoration, stormwater best
management practices (BMPs), Low Impact Development (LID), etc. A key to success is
to link the appropriate improvement option to the appropriate impairment. This is an
area where the Stream Functions Pyramid Framework can help articulate specific goals
and objectives by answering the following questions:
1. Look at Pyramid figures in Appendix A. What types of functional losses have oc-
curred in the watershed? Try to relate the losses to function-based parameters, e.g.,
channelization and loss of floodplain connectivity, and/or population declines to native
fish species.
2. Can these functions be restored? This requires an understanding of the stream
functions and the cause of the impairment, along with the potential for their improvement.
3. Look at Pyramid figures again. What supporting function-based parameters are
needed to assess improvement to the impaired functions listed in number 1?
4. What types of restoration activities are needed to improve those function-based
parameters? This could include stream preservation of healthy headwater streams
and restoration of degraded stream channels. It could also include stormwater BMPs
and LID. An experienced multi-disciplinary team will be required to link the im-
provement activity to the functional lift.
Answering these questions will allow the team to develop goals and objectives that
relate to functional impairments and their potential improvements in the watershed. For
example, depending on how the questions were answered, an example goal and associ-
ated objectives may include the following.
Goal:
Improve the health of a smallmouth bass fishery. (Note that this relates to Level 5 on the
broad-level overview Pyramid.)
Objectives:
1. Reduce stream temperature and improve dissolved oxygen to concentrations required
A Function-Based Framework » May 2012 219
-------
Chapter 11: Application of the Stream Functions Pyramid
by smallmouth bass (Level 4).
2. Improve bed form diversity to meet smallmouth bass habitat requirements (Level 3).
3. Provide floodplain connectivity to provide the flow dynamics needed for smallmouth
bass (Level 2).
4. Evaluate watershed runoff and flow duration to determine the suitability for support-
ing smallmouth bass (Level 1).
These objectives are specific function-based parameters that support the higher-level
goal of restoring a smallmouth bass fishery. They are quantifiable, tangible and can be
measured. In some cases, these parameters have measurement methods that include
performance standards. The objectives provided above are just examples and could be
changed or expanded for an actual watershed plan. In addition, a wide range of improve-
ment options may be required to meet the watershed scale goals and objectives described
above. These activities are discussed in item 4 of the Watershed Management Plans
section above.
Regulatory and Non-Regulatory Programs
The same approach provided above for watershed management plans can be used in
regulatory and non-regulatory stream improvement programs. For example, non-regulato-
ry programs, such as watershed coalitions and non-profit organizations, set programmatic
goals and objectives. As with watershed management plans, these goals are typically
established at Level 5 since they relate to some type of aquatic life impairment. An
example would be Trout Unlimited with the goal to restore a fishery. The advantage of
the Pyramid is that once the aquatic life of interest is identified, the supporting functions
can be established through quantifiable objectives. This will help the organization focus
its resources by addressing activities that specifically affect the critical functions.
The same holds true for regulatory programs like Sections 303 and 404 of the Clean
Water Act ( FWPCA, 1972). Under Section 303, states are required to have water quality
standards that support designated uses for waterways. Streams that do not meet these
requirements are placed on the 303 (d) list. For pollutant-impaired waters, Total Maxi-
mum Daily Loads (TMDLs) must then be established to address the pollutant(s) causing
the impairment. Nationwide, sediment is the second-ranked pollutant causing streams
and rivers to be placed on the 303(d)(USEPA, 2012). The causes of impairment are often
inferred from results of biological monitoring, i.e., sediment is often identified as a reason
that macroinvertebrate populations are negatively impacted.
The Pyramid could be used in impaired waters programs to establish more specific
targeted load reduction alternatives based on cause-and-effect relationships shown on the
Pyramid. For example, an initial assessment may show that the macroinvertebrate popu-
lations have lower abundance and more tolerant taxa than the reference conditions for a
given area. Next, the Stream Functions Pyramid can be used to identify all the supporting
functions that are required to support a healthy macroinvertebrate community. Third,
further assessments can be conducted to determine if those functions (using function-
A Function-Based Framework » May 2012 220
-------
Chapter 11: Application of the Stream Functions Pyramid
based parameters and a measurement method appropriate for the study) are Functioning,
Functioning-at-Risk or Not-Functioning. Finally, objectives could be established that focus
on the improvements needed to change the Not-Functioning and Functioning-at-Risk
parameters to Functioning. This would likely include more parameters than just sedi-
ment, but would yield a plan with much more detail and potential for success.
The Pyramid can also be used to improve goals and objectives related to Section 404 of
the Clean Water Act and compensatory mitigation. As was discussed above, many miti-
gation providers relate restoration goals to changes in channel dimension, pattern and
profile. Mitigation credits are often provided based on these, among other, changes
(USAGE Wilmington District et al., 2003; USAGE Norfolk District and VDEQ, 2007; and
USAGE Charleston District, 2010). The Pyramid can help practitioners develop goals and
objectives that relate directly to stream functions. Over the last few years, attention to
stream mitigation requirements associated with stream impacts from coalmining activi-
ties in Appalachia has increased. Practitioners and the regulatory community have grap-
pled with how to assess functional lift through compensatory mitigation, especially for
projects that include onsite mitigation. The process starts with setting appropriate goals
and objectives. An example of how the Pyramid can be used to provide goals and objec-
tives for on-site stream mitigation associated with large scale landscape modifications,
such as mining, is provided below.
Example Goals:
1. Achieve replacement of aquatic functions (functions are defined in a function-based
assessment) through onsite mitigation.
2. Use natural channel design techniques to re-establish a small headwater stream
network after mining activities have ceased.
Example Objectives:
1. Water quality (pH and conductivity) will have similar or more suitable ranges com-
pared to the pre-disturbance condition.
2. Bed form diversity, defined by pool-to-pool spacing and depth variability, will be
improved compared to the pre-disturbance condition and will be characterized as
Functioning using the Stream Functions Pyramid.
3. A 50-foot-wide riparian buffer composed of native grasses and trees will be established.
4. The restored channel will include large woody debris that meets a Functioning level.
5. The restored channel will have streambank erosion rates that are less than or equal to
the existing condition and meet a Functioning level.
6. Floodplain connectivity in the restored channel will meet a Functioning level. Note:
floodplain connectivity in v-shaped and colluvial valleys is characterized by a flood-
prone area that can be very small.
7. Post-restoration flow duration will match pre-disturbance flow duration.
8. Post-restoration aquatic IBI scores will match or exceed pre-disturbance values.
A Function-Based Framework » May 2012 221
-------
Chapter 11: Application of the Stream Functions Pyramid
These goals and objectives are just examples and would be modified based on the
function-based assessment and local knowledge of the site. The value of using specific
objectives, like the ones above, is that developing performance standards becomes much
easier. The performance standards simply quantify the objectives.
Restoration Project Design Goals and Objectives
The Stream Functions Pyramid Framework may be the most useful in developing
design goals and objectives, which are
Restoration projects generally developed once a restoration site has been
... selected and some form of functional or
occur at a reach scale and can ,.. , ,
existing condition assessment has been
have Significant functional lift completed. Using the Pyramid to assist with
Of Level 2 and 3 parameters, functional assessments is discussed in the
However, to achieve goals in next,section-More ^formation about
... developing goals and objectives associated
Levels 4 and 5, a combination with natural channel designs is provided
of reach scale restoration and below
adequate Upstream Developing design goals and objectives
. . . .,. can be an iterative process. Typically, a
watershed health are , , ,. „,, ,, /-a/
broad goal is established early in the process,
required. In Other WOrdSf Site perhaps prior to the functional assessment.
Selection becomes Critically This goal could relate to a broad watershed
important to achieving Level f f1'like Coring a smallmouth bass
fishery as described above under Watershed
* and O goals. Management Plans. After the assessment,
other functional impairments may be
identified that prohibit the restoration of a smallmouth bass fishery. These impairments
may occur in the upstream watershed and cannot be addressed by the restoration project.
In this case, the team would need to pick a different approach or establish new goals
based on what can be achieved at the site (reach scale). Often the goal can be revised to
improve function-based parameters in Levels 2 and 3, e.g., floodplain connectivity, bed
form diversity, lateral stability and riparian vegetation. This will not directly restore a
smallmouth bass fishery, but it can indirectly help smallmouth bass recovery by provid-
ing the channel form and habitats that they require.
This example illustrates the importance of setting project goals and objectives that are
compatible with the health of the watershed. Restoration projects generally occur at a
reach scale and can have significant functional lift of Level 2 and 3 parameters. However,
to achieve goals in Levels 4 and 5, a combination of reach scale restoration and adequate
upstream watershed health are required. In other words, site selection becomes critically
important to achieving Level 4 and 5 goals.
A Function-Based Framework » May 2012 222
-------
Chapter 11: Application of the Stream Functions Pyramid
Common Mistakes and Ideas for Improvement
A common stream restoration goal is simply to improve aquatic habitat (Fischenich,
2006). This is a poorly stated goal because it does not tell the reader what organism the
habitat is for. Habitat requirements for mussels are different than habitat for a trout. If a
habitat goal is going to be used, the goal, at a minimum, should state what species the
habitat is for, e.g., "The goal of this project is to restore a southeastern native brook trout
fishery." Now the reader knows why the project is proposed. Of course, the term "habi-
tat" is still broad and could include many things. So an even better goal would be "To
improve the abundance of native brook trout populations within the project reach." This
is a goal that can be evaluated, and the measure of success is very specific. Objectives
associated with this goal would identify the lower-level function-based parameters that
must be Functioning in order to increase the abundance of native brook trout. And since
this is a Level 5 goal, a thorough assessment of the watershed must be completed to
determine if the upstream conditions will support brook trout, even after reach scale
restoration. If not, another project reach, perhaps farther upstream, will need to be selected.
Another common and poorly stated goal is to improve water quality. Like habitat,
water quality is a very broad concept and means different things to different people. For
example, practitioners in West Virginia will typically equate water quality to pH and
conductivity because of their work with the coalmining industry. Practitioners working
in the eastern US Coastal Plain region will typically think of water quality as a nutrient
(e.g., nitrogen and phosphorus) issue. Practitioners in the eastern US Piedmont and Moun-
tain regions may think of water quality as a sediment or turbidity problem. Practitioners
in the Pacific Northwest often think of water quality as a temperature problem. There are
many other examples across the country, depending on the primary causes of water
quality impairment. The key is to be specific. Use the goal to clearly establish why water
quality is being addressed: to improve pH, conductivity, nutrients, sediment or other
physicochemical properties. And, as with all of the goals, the next step is to develop
objectives that identify the supporting, lower-level function-based parameters that must
be Functioning in order to meet the goal. This also provides an opportunity to determine
if stream restoration is the appropriate solution, or if other techniques are required. For
example, stream restoration may have a minimal influence on conductivity and pH.
11.3 » FUNCTION-BASED STREAM ASSESSMENTS
The Pyramid is a framework that can be used as an aid in developing and reviewing
function-based stream assessments. Somerville (2010) showed that stream assessments
are often completed for a variety of regulatory and non-regulatory reasons, and range
from broad assessments of stream condition to specific regulatory requirements. Three
uses of function-based stream assessments will be discussed below and include:
• Determining restoration potential and functional lift;
• Determining stream functions lost and gained as part of a compensatory mitigation
project; and
• Locating potential stream restoration projects as part of a watershed management plan.
A Function-Based Framework » May 2012 223
-------
Chapter 11: Application of the Stream Functions Pyramid
A function-based assessment may include parameters from the Pyramid that are
functions themselves; parameters that are not functions but help to describe the function
from that category, e.g., bank height ratio from the Geomorphology category to help
explain flow dynamics and floodplain connectivity. Parameter selection will be deter-
mined by the purpose of the assessment, the funding level and the geographic region. For
example, flow duration is more limiting in some regions (and for some restoration types)
than it is in others. Simple parameters may be selected for rapid-based assessments, and
more complex parameters (that are also functions) may be selected for more intensive studies.
Regardless of the reason for completing function-based stream assessments, the following
steps should be completed when using the Pyramid as a guide.
1. Determine the purpose of the assessment.
2. Select parameters from the Pyramid and/or other sources of information about parameters
that describe stream functions relevant to the study. Include supporting functions.
3. Determine the appropriate methods for measuring the parameters, e.g., rapid versus
intensive, and simple versus complex. This selection will also be dependent on the
budget and purpose of the assessment.
4. Determine if the measurement methods need to be adapted based on unique regional
characteristics, e.g., karst topography or endangered species.
5. Review the performance standards that are associated with the measurement meth-
ods, and determine if they are appropriate based on local environmental conditions
and the purpose of the assessment. If possible, update performance standards with
information from local reference streams.
6. If deemed necessary by the purpose, develop a scoring method to determine the
overall functionality score of the stream reach, i.e., Overall Functioning, Functioning-
at-Risk or Not Functioning. Consider having an overall score per functional category as
well, e.g., Geomorphology, to help show where functional problems may exist.
7. Establish the length of the assessment (monitoring) period.
8. Implement function-based stream assessment, evaluate its effectiveness in assessing
stream functions, and adapt method as necessary.
A description for each of the three general uses for stream assessment methods is
provided below, along with examples of parameters from the Pyramid that could be
included for that assessment.
Determining Restoration Potential and Functional Lift
The Stream Functions Pyramid Framework can be used to determine the restoration
potential at a proposed project site. Restoration potential is the highest level of restoration
or functional lift that can be achieved given the site constraints and health of the water-
shed. Once the restoration potential is known, specific design goals and objectives can be
established, or original goals and objectives may need to be refined.
These assessments may include parameters from all five levels of the Pyramid that
A Function-Based Framework » May 2012 224
-------
Chapter 11: Application of the Stream Functions Pyramid
quantify and describe the pre-restoration Restoration potential is
condition of the channel. Common Level 1 , - , , . . ,
. , , , • v 4.- / c 11 *ne highest level or
parameters include the precipitation/rainfall
relationship, channel forming discharge and restoration Of functional lift
flood frequency. These parameters are used that Can be achieved given
to quantify and describe the transport of fne sjte constrajnts an£/
water from the watershed to the channel, tutu ^
and they are needed in order to complete the "ea/*" of the watershed.
Hydraulic and Geomorphology portions of Once the restoration potential
the assessment. Common Level 2 parameters /s known. Specific design
include both flow dynamics and floodplain fo ^ Qu- tives cgn b&
connectivity, since these are critical tor
determining channel stability. Flow dynam- established. Or Original
ics are typically assessed by measuring goals and Objectives may
stream velocity, shear stress and stream need to be refined
power. Floodplain connectivity is most
commonly assessed using the bank height ratio and entrenchment ratio. If the bankfull
stage is unknown, stage-versus-discharge estimates using a hydraulic computer model
can also be used to assess floodplain connectivity. However, to complete a proper hydrau-
lic assessment to determine channel stability, field surveyed cross sections are required. A
longitudinal profile is helpful for measuring bank height ratios along the reach. The
profile can also be used for Level 3 assessment.
Level 3 parameters include sediment transport competency and capacity, channel
evolution, streambank erosion rates, bed form diversity, large woody debris assessments,
and riparian vegetation assessments. These parameters may be measured using rapid or
more intensive approaches, based on the complexity of the project and funding level.
However, the main purpose of the Level 3 assessment is to determine if the channel is
vertically and laterally stable. Channel evolution assessments are used in combination
with the above measures to estimate the future trend, i.e., whether the stream is evolving
towards stability or instability. Of course, some stream types are naturally unstable;
however, these streams should not be candidates for restoration. Common Level 4 param-
eters include basic water quality measures like pH, conductivity, temperature and dis-
solved oxygen. Assessments in the eastern US Coastal Plain region may also include
nutrient assessments. Level 5 function-based parameters sometimes include macroinver-
tebrate and fish community assessments. Landscape connectivity is rarely used, but
should be considered for providing watershed scale improvements.
The assessment results can then be used to determine the restoration potential. For
example, the assessment may indicate that a stream reach is severely incised with ex-
treme bank erosion, low bed form diversity, and no riparian vegetation. If this site is in a
rural setting (low lateral constraints) with a healthy watershed, then the restoration
potential is high because functional lift can likely be achieved through Level 5. However,
if this same site is in an urban area or a setting with lateral constraints — like a road or
A Function-Based Framework » May 2012 225
-------
Chapter 11: Application of the Stream Functions Pyramid
even cropland — that cannot be removed from production, then the restoration potential
is lower because the functional lift may only occur in Levels 2 and 3.
Table 11.1 can be used to illustrate the baseline functions at the project site along with
the proposed functional lift; the examples provided above are shown in the table. The
values are arbitrary and not associated with a project. The purpose is simply to show
how the function-based parameters, measurement methods and performance standards
may be used as part of an assessment. The function-based parameters and measurement
methods are selected based on the restoration potential, and the performance standards
are used to quantify the functional lift.
Determining Stream Functions Lost and Gained as Part of a Compensatory
Mitigation Project
The 2008 Mitigation Rule recommends that some type of functional assessment be
completed at the permitted impact site and the mitigation site. The purpose of the func-
tional assessment is to determine the functional loss at the permitted impact site and the
functional lift at the mitigation site. Functional lift is defined as the difference between
the pre-restoration and post-restoration condition. This process is intended to result in
replacement of aquatic resources, in this case, the stream ecosystem.
Developing a function-based assessment for this purpose would be very similar to the
one used to determine restoration potential and functional lift (described above). One
difference is that the assessment would need to be applied at the permitted impact site
and the mitigation site. The level of assessment will vary at the impact site, as the level of
impact varies from minor (e.g., a culvert replacement or utility crossing) to major (e.g.
surface mining or new road construction). For example, if only a few parameters are
being affected, then only a few parameters need to be included in the assessment. If all
five levels are being affected, the assessment should include parameters from all five
levels. For the mitigation sites, the assessment can be more consistent with, and will be
similar to, what is described in the restoration potential and functional lift section above.
These parameters would then be assessed as part of the monitoring phase, and the data
used to determine if performance standards are being achieved.
Locating Potential Stream Restoration Projects Using a Watershed
Management Plan
Watershed management plans are becoming common among non-regulatory and
regulatory programs. These plans are typically used to (1) identify the sources of stream
and water quality impairments; (2) identify stream reaches and sub-watersheds that are
relatively un-impacted, and (3) develop management plans to improve stream health and
water quality. Federal programs that support watershed management plans include grants
provided by Section 319 of the Clean Water Act (FWPCA, 1972), Total Maximum Daily
Loads (TMDL), 2008 Mitgation Rule, and others.
Function-based stream assessments fit well with watershed management plans. They
are often used as the method for differentiating between impaired and unimpaired
A Function-Based Framework » May 2012 226
-------
Chapter 11: Application of the Stream Functions Pyramid
^
o
cc
o
oo o
LLJ —
h— ^3
OO 2
0 0
n c_j
0
^
PRE-RESTOR
CONDITION
CD
H-
^t
OC
LU
— i
__J
^f
CD
—
^
CC
LLJ
— 1
F
LLJ
LLJ
cc a
s •- ^
CD 05 _
w 05 9?
-_ 4_i E 05 CO
CO
C
c
o
•j~.
LLJ LLJ ^
> F
1 1 1 <5
_l O t-
C
^
LL
CD
CO
C
'E
o
o
C
LL
o
z
o
CO
-t-J
CO
'05
I
-* O
C '^
CD CD
CO CC
CO
C
C
o
•~
o
C
^
LL
O
CO
CO
C
'E
o
o
C
LL
o
z
C
05
E
.C
f5
C
05 O
-t-J '-P
C CD
LU CC
Floodplain
Connectivitv
CO
o
"5
CD
>
I
1
CM
CO
C
c
o
•j~.
o
C
^
LL
ID
2
CO
C
'E
o
o
C
LL
o
z
A
"5
o
Q.
6 °^
O CD
O Q.
D_ co
Bed Form
diversity
CO
C
C
o
•j~.
o
C
^
LL
CD
05
CO
CD
-t-J
CO
CO
C
'E
o
o
C
LL
o
z
CO
2
CM
05
CO
CD
CO
c
o
E
CO
c
o
J3
Channel Evo
CO
C
c
o
•j~.
o
C
^
LL
00
A C C
(,, CD CD
'~ CO E ^
JZ J- 3 .ti
1 ? 0 S
> b c CD
!
*i
1
CO
c
'^-
o
'•»-'
0 _^
5 CO
LL ~CC
f—
Width is 12
meters with
some humar
activity
D_
CQ
cc
Riparian
Vegetation
CO
C
c
o
•j~.
o
C
3
LL
g
O
_l
o
CO
C
'E
o
o
C
LL
o
z
CO
±
CO
CO
CO
z
E
LU
CO
>.
~
!5
CD
-t-J
CO
CD
05
-t-J
CD
CO
o
o
Q.
O
E
o
05
0
1
CO
CO
C
C
o
•~
o
C
3
LL
CO
£
P ^ C
CO C c
CD CD (C CO 0
05 2 .C ,J2 •— .—
C +-1 o 05 ° ^
Cj ^ CD 05 ^ CT
CO 3 2 E CO 2
CO
C
'E
o
o
C
LL
o
z
CO
-t-J
C CO C
CD _ „ 05 05
6 E S -§ 05 E
I 3 i_ i_ C CO >-
05
-t-j
CD
05
Q.
E
05
F
>,
cr
05
-t-j
1
o
E
05
O
O
O
'co
0_
1
•*
CO
C
C
o
•~
o
C
3
LL
„
CO
C
'E
o
o
C
LL
o
z
c x
C 05
05 c
^ §
.5 '^
'co"i:
.bz 0
> 0
05
-t-j
CD
05 CO
Macroinvert
Communitie
CO
o
o
in
i
in
cc
LLI
_l
m
A Function-Based Framework » May 2012
227
-------
Chapter 11: Application of the Stream Functions Pyramid
stream reaches. To complete this task, these assessment methods are often implemented
differently at the watershed scale and the reach scale. At the watershed scale, GIS, remote
sensing and aerial photography are used to broadly assess parameters that would indicate
stable, healthy streams versus unstable streams. These parameters from the Pyramid
might include riparian vegetation, lateral stability and landscape pathways, all of which
can be assessed with GIS and aerial photography. Some watersheds may be included in
FEMA-regulated floodplains and contain Hydrology and Hydraulic characterizations that
can be used to estimate floodplain connectivity and flow dynamics.
From this initial screening, on-the-ground, rapid-based assessments can be used to
further determine channel stability, channel evolution, restoration potential, basic water
chemistry and biological health. Rapid methods are needed so that long reaches of chan-
nel can be assessed in a relatively short period of time. The result is a map showing the
location of impaired stream reaches, their proximity to other land uses, and a priority
ranking for restoration. For example, an impaired stream downstream of a high quality
sub-watershed, or an impaired reach between two stable reaches, would be high priori-
ties because the functional lift would transcend the project reach length. Conversely, an
impaired reach downsteam of multiple point source discharges, or areas of rapid develop-
ment, may receive a lower priority; therefore, other techniques like stormwater BMPs and
Low Impact Development may be recommended instead. Once reaches are selected for a
project, a more intensive assessment method to determine channel stability and restora-
tion potential can be implemented.
Additional information about conducting watershed assessments can be found at
http://water.epa.gov/type/watersheds. There is a wealth of information on this website, but
one tool that my be particularly helpfulfor evaluating potential stream restoration sites is
the Recovery Potential Project, a landscape screening tool for assessing the restorability of
impaired waters.
11.4 » KEY PARAMETERS
The Stream Functions Pyramid includes over 30 parameters, but it is unlikely that a
project would ever need to assess them all. However, there are core or key parameters
that can be listed for a variety of common projects, such as restoring channelized
streams in alluvial valleys back into meandering streams, restoring small headwater
streams associated with mining, and im-
The Stream Functions proving salmonid fish habitat. Examples
Pyramid includes Over 30 °f key function-based parameters that
parameters, but it is unlikely sh°uld be evaluated before and after£restora-
tion are provided below. A variety of rapid
that a project WOUld ever ancj more intensive measurement methods
need tO assess them all. are also provided.
Restoring Channelized Streams in Alluvial Valleys to Meandering Streams
Many projects in the eastern US attempt to restore streams that were enlarged and
A Function-Based Framework » May 2012 228
-------
Chapter 11: Application of the Stream Functions Pyramid
deepened through channelization and incision. These projects occur in alluvial valleys, in
both urban and rural settings, and with a variety of substrate compositions. The Rosgen
Priority Levels are often used as an approach for restoring these streams. Figures 11.la
and 11.Ib show before and after photos of a stream restoration project in the Coastal
Plain of North Carolina. Figure 11.la shows a channelized, incised stream that lacks bed
form diversity due to low sinuosity and dredging. There is minimal riparian vegetation
and nutrient runoff that can easily enter the stream from the adjacent cropland causing
eutrophication. Figure 11.Ib shows the same project site approximately one growing
season after restoration construction was completed. The stream is shallower than the
pre-restoration condition, creating enhanced floodplain connectivity and an elevated
water table that supports the development of riparian wetlands. The meandering pattern
carries both baseflow and bankfull flows effectively, providing longer retention times and
opportunities for denitrification. The biggest driver of denitrification is the increased
floodplain access by stormflows, water storage on the floodplain, shallow depth to the
water table, and establishment of a woody riparian buffer over time.
FIGURE 11.1A PRE-RESTORATION
FIGURE 11.1B POST-RESTORATION
Source: Reproduced with permission from Michael Baker Corporation
This project, like most other restoration projects where channelized streams are
converted back into meandering systems, highlights four key parameters that must be
addressed to achieve project success. The key parameters include: floodplain connectivity,
bed form diversity, lateral stability and riparian vegetation. These function-based param-
eters are shown below in Table 11.2. The second column provides measurement methods
that can rapidly be assessed with minimal field measurements. The third column pro-
vides measurement methods that provide a
more detailed assessment of the stream The key parameters include:
reach; however, they also require more effort. f,oodp,ajn conneCtivity, bed
These more intensive measurement methods
require more time in the field to collect data form diversity, lateral Stability
and, in some cases, require repeated monitor- and riparian vegetation.
A Function-Based Framework » May 2012
229
-------
Chapter 11: Application of the Stream Functions Pyramid
ing over several years, e.g., developing rating curves, establishing erosion rates and mea-
suring vegetation growth.
If these four function-based parameters are addressed properly along with proper site
selection, then there is a high probability of achieving success by improving the physical,
chemical and biological integrity of the stream. This table should not be used to assume
that parameters in other levels of the Pyramid are not important (these all come from
Levels 2 and 3). Rather, the intent is to show that these parameters are generally the
critical foundation to a healthy stream in most alluvial valleys.
TABLE 11.2 KEY PARAMETERS FOR ASSESSING STREAM FUNCTIONS ASSOCIATED WITH
RESTORING MEANDERING STREAMS
PARAMETER
Floodplain Connectivity
Bed Form Diversity
Lateral Stability
Riparian Vegetation
SIMPLE MEASUREMENT
METHOD
Bank Height Ratio,
Entrenchment Ratio,
Percent Riffle and Pool
Streambank Erosion Rates
using BANGS model
Riparian Buffer Width
MORE INTENSIVE
MEASUREMENT METHOD
Rating curves (discharge vs.
stage)
Depth Variability
Measuring Streambank
Erosion Rates with
permanent cross sections
Riparian Vegetation Density
and Composition-
Vegetation Plots
Restoring Small Headwater Streams
The key parameters listed in Table 11.2 would need to be modified slightly for assess-
ing stream functions associated with the restoration of small headwater streams, such as
those commonly found in the Appalachian Mountains. The restoration of high-gradient,
very small intermittent and ephemeral channels as part of stream mitigation projects is
common in coalmining regions. In other areas of the Appalachian Mountains, Trout
Unlimited and resource agencies work to restore native brook trout populations in head-
water perennial mountain streams that are typically located in colluvial and v-shaped
valleys. Unlike the lateral meandering streams discussed above, these streams dissipate
energy through vertical meandering of the stream bed, i.e., through a step-pool bed form
sequence (Wohl, 2000). These streams do not have floodplains that are built by river
meandering processes, but rather have floodprone areas that often extend the width of
the bowl- or v-shaped valley. Figures 11.2a and 11.2b show an example of a small head-
water mountain stream restoration project. Figure 11.2a shows the stream before restora-
tion. The bed form is devoid of pools due to past cattle trampling and channel widening.
Figure 11.2b shows the project after restoration construction. Boulder and wood struc-
tures were used to create a step-pool bed form, re-establishing the vertical meandering
processes. A bowl-shaped floodprone area provides energy dissipation during flood
A Function-Based Framework » May 2012
230
-------
Chapter 11: Application of the Stream Functions Pyramid
events, and a riparian buffer was established to provide lateral stability.
FIGURE 11.2A PRE-RESTORATION FIGURE 11.2B POST-RESTORATION
Cows are periodically allowed to graze.
Source: Reproduced with permission from Michael Baker Corporation
The same key function-based parameters associated with a natural channel design and
listed in Table 11.2 are included here in Table 11.3, with one minor exception. Since these
channels do not have floodplains, the function-based parameter is changed to floodprone
area connectivity, as it is still important for the channel to only carry the amount of
water necessary for sediment transport requirements. Flood flows should be transported
in the floodprone area. The simple measurement method for bed form diversity also
changes, from percent riffle-pool to pool-to-pool spacing, which is a better measure of
vertical meandering and has better performance standards (Leopold, 1994; Gregory et al.,
1994; Whittaker, 1987; Chin, 1989, and Grant et al., 1990).
TABLE 11.3 CRITICAL CATEGORIES FOR ASSESSING FUNCTIONS BEFORE AND AFTER
STREAM RESTORATION PROJECTS
PARAMETER
SIMPLE MEASUREMENT
METHOD
MORE INTENSIVE
MEASUREMENT METHOD
nuuu|jiciiii isUMimoiiviiy
(Floodprone Area
Connectivity)
Bed Form Diversity
Lateral Stability
Riparian Vegetation
DCIIIK. neiyiH ncmu,
Entrenchment Ratio,
Pool-to-Pool Spacing
Streambank Erosion Rates
using BANGS Model
Riparian Buffer Width
ndLiny v^uiveb vuibuiidiyt;
vs. stage)
Depth Variability
Measuring Streambank
Erosion Rates with
Permanent Cross Sections
Riparian Vegetation Density
and Composition-
Vegetation Plots
A Function-Based Framework » May 2012
231
-------
Chapter 11: Application of the Stream Functions Pyramid
Table 11.3 is primarily for natural channel design, i.e., these parameters are key
design parameters that can have a major effect on creating higher-order functional im-
provements. Additional function-based parameters may be selected when evaluating
headwater mountain stream restoration projects for functional lift that is associated with
mining activities. Table 11.4 provides an example of the minimum function-based param-
eters per functional category that are recommended. Measurement method examples are
provided that would be appropriate for a mitigation project; some are rapid and others are
more intensive.
TABLE 11.4 POSSIBLE FUNCTION-BASED PARAMETERS AND MEASUREMENT METHODS FOR
EVALUATING FUNCTIONAL LIFT IN SMALL, HIGH GRADIENT STREAMS
FUNCTIONAL
CATEGORY
Hydrology
Hydrology
Hydraulics
Geomorphology
Geomorphology
Geomorphology
Geomorphology
Physicochemical
Biological
FUNCTION-BASED
PARAMETER
Rainfall /Runoff
Flow Duration
Floodplain (Floodprone area)
Connectivity
Large Woody Debris
Bed Form Diversity
Lateral Stability
Riparian Vegetation
Water Quality
M a c ro i n ve rte b rate
Communities
MEASUREMENT METHOD
^^•_
Rationale Method
Rapid Indicators
Bank Height Ratio
Entrenchment Ratio
Large Woody Debris Index
Pool-to-Pool Spacing
Depth Variability
BEHI/NBS
Buffer Width
Buffer Composition
Buffer Density
PH
Conductivity
State Protocol, if available
There are exceptions to the key parameters listed above. It is likely that many small,
headwater ephemeral stream channels in the mountain regions are the product of erosion
and channel formation due to land clearing practices during post-European settlement. In
some of these systems, forest regeneration has occurred over the decades, and the chan-
nel that formed is stable. However, from a functional standpoint, it would be better to
have valley bottoms rather than channels that provide greater storage capacity for water,
wood, and other forms of organic matter. Restoration would typically not be recom-
mended in stable environments; however, small-channel and no-channel approaches for
restoring disturbed systems are being investigated by various researchers and practitio-
ners. Examples of natural channel design in small headwater channels can be reviewed at
https://louisville.edu/speed/civil/si.
A Function-Based Framework » May 2012
232
-------
Chapter 11: Application of the Stream Functions Pyramid
Key Parameters for other Types of Restoration
The key parameters listed above are applicable to many full-scale restoration projects.
However, some forms of restoration do not require aggressive changes to channel form,
and different key parameters may be required for restoration success. Water removal
impacts in the arid West are an example where the key parameters listed above would
not apply. In these environments, the channel form may include floodplain connectivity,
bed form diversity, laterally stability, and have riparian vegetation common for arid
regions; however, historically perennial streams can become ephemeral due to excessive
water withdrawals. In these cases, flow duration is the key parameter and the restoration
activities may include policy/management changes rather than natural channel designs.
Other examples of restorations that may require minimal or no adjustments to chan-
nel form include removal of fish passage impediments and eliminating water quality
impairments associated with point-source discharges and stormwater runoff. However,
these key parameters listed above should still be assessed, or at least considered, before
moving forward with other forms of restoration, especially for perennial streams in
alluvial valleys. More likely, additional function-based parameters would be added to the
list, rather than removing them.
11.5 » REVIEWING EXISTING STREAM ASSESSMENTS
Government agencies often want to evaluate existing stream assessment protocols
before making the decision to develop a new one. Somerville and Pruitt (2004) and
Somerville (2010) provide a good starting point for evaluating existing stream assessment
protocols. New protocols continue to be developed, especially related to stream mitiga-
tion. The draft Regional Guidebook for High-gradient Ephemeral and Intermittent Head-
water Streams, USAGE (2010), is an example of a functional assessment methodology
that has been developed in response to mitigation requirements in coalmining regions of
West Virginia and Kentucky. Given the volume of existing assessment methodologies, it
is important to have criteria for selecting an existing methodology or for making the
decision to develop a new methodology. The following checklist may help with this decision.
Checklist for Selecting Existing Stream Assessment Methodologies
1. Determine why a stream assessment is needed. What is the purpose?
2. Is the assessment needed to meet regulatory requirements?
3. Is the existing stream assessment protocol appropriate for your region? In other
words, some protocols are developed for very specific environmental settings and
conditions, e.g., high gradient or arid.
4. Has the existing stream assessment protocol been peer reviewed, validated, or other-
wise assessed for accuracy and precision in relation to direct functional measures?
5. How much is already known about the functional impairments of the watershed?
Some understanding of existing impairments is helpful when selecting an existing
protocol because the impairments can be related to the function-based parameters
from the Pyramid. Then these parameters can be compared to the parameters as-
A Function-Based Framework » May 2012 233
-------
Chapter 11: Application of the Stream Functions Pyramid
sessed in the protocol. If there is a good match, then the existing protocol may be
selected. Otherwise, other protocols should be reviewed and potentially new proto-
cols may needed to be developed.
6. Are lower-level functional categories included, e.g., Hydrology, Hydraulics, and
Geomorphology? Generally, existing protocols are weak in these categories. Review
the protocol to ensure that the supporting/"driver" parameters are included.
7. Are the key parameters described in the above sections included? If not, is there a
good reason?
11.6 » DEVELOPING DEBITS AND CREDITS
The development of stream debit and credit determination methods continues to
evolve as USAGE Districts implement the 2008 Mitigation Rule. The Rule does not
provide a formula for developing debit or credits. It simply states that a description of the
debits or credits will be provided, including the rationale used. In some regions, IRTs have
incorporated credit determination methods into SOPs; however, in other areas, the credit
determination method is left up to the mitigation provider. The Rule defines debits as a
unit of measure that accounts for the functional loss at a permitted impact site. Some
mitigation SOPs, like the Unified Stream Methodology (USAGE Norfolk District and
VDEQ, 2007) and the Charleston, SC SOP
The Stream Functions (USACE charleston District> 201°) Provide
debit calculations based on a stream condi-
Pyramid Can alSO be USed tO tion assessment, similar to a function-based
Separate restoration efforts assessment. However, some of the tech-
that improve Level 2 and 3 niclues described in the Function-based
, ,. . ,, ,, Assessment section above could be used to
functions, and those that , ,. , , c . , ,
better link the functions lost at a permitted
restore through Level 5. impact site to the functions gained at a
As SUChf IRTs may Choose tO mitigation site.
consider creating two levels Stream ™idgation crefs are ufts of
measure that represent the accrual or attain-
of restoration: Restoration 1 ment o£ stream £unctions at a compensatory
and Restoration 2. mitigation site (33.C.ER. § 332/40 C.F.R. §
230). The accrual or attainment of stream
function occurs through a variety of approaches, including restoration, enhancement,
re-establishment and preservation. The Pyramid Framework can be used to help show
the functional lift, especially with stream restoration approaches. Stream restoration is
defined in the 2008 Mitigation Rule as the "manipulation of the physical, chemical and
biological characteristics of a site with the goal of returning natural/historic functions to
a former or degraded aquatic resource." Most stream mitigation SOPs cite this definition;
however, functional lift is often tied to the Priority Levels of Restoration (Rosgen, 1997)
and/or changes to stream dimension, pattern and profile (Somerville, 2010).
A Function-Based Framework » May 2012 234
-------
Chapter 11: Application of the Stream Functions Pyramid
This has led to several problems, including: (1) incentivizing maximum channel
manipulation to show changes in dimension, pattern and profile to receive the maximum
amount of credits; (2) focusing the objectives and performance standards on dimension,
pattern and profile changes instead of stream functions or function-based parameters,
making the communication of functional lift difficult; and (3) removing evidence of
functional lift from the evaluation of project success. This credit determination method
has resulted in many projects being evaluated simply on visual observations of channel
stability, in-stream structure integrity, and condition of the riparian buffer. The Stream
Functions Pyramid, and the forms shown in the assessment section, can help articulate
function-based goals, develop function-based assessments, and then develop credit
determination methods based on the potential functional lift. Examples of how to do this
are provided in the next section.
The Stream Functions Pyramid can also be used to separate restoration efforts that
improve Level 2 and 3 functions, and those that restore through Level 5. As such, IRTs
may choose to consider creating two levels of restoration: Restoration 1 and Restoration
2. Restoration 1 would restore functions through Level 5 and represent the highest level
of restoration achievable. This would require reach-scale restoration and an upstream
watershed that supports aquatic life identified
in Level 5. It could also include watershed- Qne value ;„ fhjs restoratjon
scale restoration tor small headwater sys-
tems. More details are provided below about level Approach IS that it
credits; however, 1 credit per foot is proposed dearly identifies function-
as the maximum number attainable, essen- based parameters that a
tially representing 100% restoration. Restora- .,. ,. . .
_ . %, . , , r. , „, „. f mitigation provider can
tion 2 is also denned as the restoration of
reach-scale functions; however, the upstream Control (Restoration 2) verSUS
watershed may not be suitable for supporting function-based parameters
species of interest in Level 5 The restoration fhat &fe mQfe dependent on
project may still be worthwhile (based on the
function-based assessment); however, func- Upstream watershed
tions are only restored through Level 3. condition (Restoration 1).
Therefore, the maximum achievable credits
for Restoration 2 would be less than for Restoration 1; perhaps the maximum is 0.8
credits per foot for the example. However, if a mitigation provider continued to work in
the watershed and showed appropriate levels of functional improvement in Level 5, the
IRT may want to allow the provider to request the additional 0.2 credits per foot to
achieve the full 1.0 credit per foot. This would offer incentive for the mitigation providers
to perform watershed-scale restoration.
One value in this restoration level approach is that it clearly identifies function-based
parameters that a mitigation provider can control (Restoration 2) versus function-based
parameters that are more dependent on upstream watershed condition (Restoration 1).
For a Restoration 2 example, projects that restore meandering pattern to channelized
A Function-Based Framework » May 2012 235
-------
Chapter 11: Application of the Stream Functions Pyramid
streams would show functional improvement in the key parameters shown in Table 11.2
(floodplain connectivity, bed form diversity, lateral stability, riparian vegetation). The
mitigation provider has a lot of control over the design and functionality of these param-
eters. This should improve communication between the provider and the IRT, making
the development of performance standards much more specific and quantitative than
many current approaches that simply deal with channel form (dimension, pattern and
profile). However, further improvements in Levels 4 and 5 are dependent on upstream
watershed conditions. To achieve Restoration 1 and receive full restoration credit, the
upstream watershed condition combined with reach-scale restoration creates a Functioning
ecosystem through Level 5. The mitigation provider does not have control of the upstream
watershed condition; however, they do have control over how the project site is selected.
Debit and Credit Templates Overview
The purpose of this section is to show how the Stream Functions Pyramid Framework
can be used as an aid in developing stream debit and credit determination methods.
Example debit and credit determination templates will be provided, along with examples
and case scenarios to illustrate how the Pyramid Framework can be used — at least at a
broad level. The main goal of this section is simply to illustrate how the Pyramid might
be used to develop debits and credits. It is not intended to be a policy recommendation,
but rather "food for thought". It is a tool, not a rule; however, the approach does try to
address requirements in the 2008 Mitigation Rule.
Example templates are provided below to aid IRTs in developing debits and credits.
The templates are meant to provide IRTs with ideas on how they can create an SOP that
utilizes the Stream Functions Pyramid to help show functional lift. They should be
modified to fit local needs and conditions. The SOP template does not address credit
release schedules, land protection measures, monitoring designs, service area delineation
or other elements of a stream mitigation plan. Rather, the SOP templates focus on how to
show appropriate compensation by matching the functions lost at the impact site to the
functions gained at the mitigation site by comparing the difference between pre- and
post-conditions. These conditions are assessed using the function-based parameters,
measurement methods and performance standards from the Pyramid Framework.
Example applications of the template for several impact scenarios (debits) and mitigation
scenarios (credits), representing a wide range of conditions from across the country, are
provided in Appendix B. The debit scenarios include:
1. Culvert installations,
2. Channelization and bank hardening, and
3. Surface mining of high gradient streams.
The credit scenarios include:
1. Restoration of incised streams;
2. Restoration of stream flow for channels that have excessive water withdrawal;
A Function-Based Framework » May 2012 236
-------
Chapter 11: Application of the Stream Functions Pyramid
3. Salmonid fish passage and habitat restoration; and
4. Restoration of high gradient, headwater streams.
Debit and Credit Templates Structure
There are three sample debit and three sample credit templates provided below, along
with a description of each. Template 1 for debits and credits shows the functional loss
and lift, respectively. Template 2 provides a place where the user can write notes about
the rationale used to complete Template 1. There is a Debit Template 2 and a Credit
Template 2. Template 3 provides a method for
calculating debits (Debit Template 3) and The main goal of this Section
credks (CredkTemplate 3) A.detailed de- fo sj , ^ mustrate how the
scnption of each is provided below.
The Debit Template 1: Functional Loss Deter- Pyramid might be US6d to
mination (Table 11.5) shows the Pyramid level develop debits and Credits. It
number and category name. For each catego- /s not intended to be 3 policy
ry (Hydrology, Hydraulics, etc.) the table . ,. ,,
shows the parameter selected from the recommendation, but rather
Pyramid, the measurement method, the "food for thought". It IS 3
pre-disturbance condition and the post-dis- tool, not a rule; however, the
turbance condition The key parameters are approach does try to addreSS
selected based on the type of impact and
whether or not the impact is expected to requirements in the 2008
affect the parameter. For example, if a culvert Mitigation Rule.
is going to be installed in a stream with a
mature bottomland hardwood forest, the riparian vegetation parameter would be select-
ed. This would show that the buffer is Functioning before the permitted impact and is
Not Functioning after the impact. All the information needed to complete this table is
provided in Chapters 5-9. A summary is provided in Appendix A.
The Credit Template 1: Functional Lift Determination (Table 11.6) is identical to the Debit
Template 1 (Table 11.5) with two exceptions. The pre-disturbance condition and post-
disturbance condition have been changed to pre-restoration condition and post-restora-
tion condition. Parameters and measurement methods are selected to best represent the
potential improvement in stream functions.
A Function-Based Framework » May 2012 237
-------
Chapter 11: Application of the Stream Functions Pyramid
"2.
o
Q
l~~ S
0 LU
Q_ tJ
LU <
1- CQ
0 CC
Q_ a
LU
O
CQ
ll
9 E
LU S
OC O
Q_ O
CD
?
5
CC
LU
^
CD
ZZ
I —
OC
LU
+L 0)
„ , (D (D -^
O) O) . . O) -C O CO
c c o c -^ c >
'c 'c Z 'c S c "°
o o ,_ o ° E j£
£ o 'o ° 'o "§ £ "g
£§§.<£ §^03.2
LULLLLCCLLJ2 Q.OO
03
-3
_ -l-i
i_ CD ^
0 > -0 05
03^^^^! -
^03 ,_ •— ^ i- "O
>- ~ C/3 >- O) C/3 r-
03 ^J CD 03 c CD 4-1
C \— ,- 03 C/3 ,- ,-
LU ca b T3 3 b b
4-»
^ i O 03 03
U> U>-^ O) ^ 0
c c ^ c +-• c
c c o c S c P
.2 .2 ^ .2 ° E cB
i;oo--o0 o"° ^
4*ij C CZ CC C C/3 i— ^
LULLLLtDLLja CioO >
'c
03 -,-, 03
03 1 C 03 E
C" "^ '^ C" t*^ ^^
-- E - = o
i- CD i- D) C/3 _c
^ a) ^ a) c co 4-1
£
1—
| | |
C o 03 C/3 /— /—
LU CD "D 3 b b
-j?
ni 03
LJJ -C 03 E O ^
|§ i'l^EsI
< h=
LU LU
CC
LU
| —
LU
^
. "~ ^
03 -2 03 "O _ £
-^ °2 -^ •— 2 as
^ ^ S.
03 2 b 2 -| CD
C/3 (^ O >^ 03 -C
£ CL£ CL CC O
a>
i = ll
< 0 I -£
_1 CD >
LU LU ^
> H^
1 1 1 <3.
__l O <-
03
o
E
X
LU
"o.
E
CO
X
LU
03
a.
E
CD
x
LU
03
a.
E
X
LU
03
a.
E
CD
X
LU
03
a.
E
CD
X
LU
a>
c
'E
o
o
c
LL
o
~Z-
LO
CM
O)
c
'c
o
ts
c
LL
O
4-1
0)
'03
I
-* O
c '^
CD CD
CQ CC
a>
c
'E
o
o
c
LL
o
~Z-
^
O)
c
'c
o
ts
c
LL
O
CO
C
03
E
.C
o
c
03 O
4-» 'P
C CD
LU CC
>.
c •>
CD '-P
"Q. ^
"D c
O c
0 0
LL O
C/3
O
"5
CD
T3
I
1
CM
>.
O)
o
o
^
ca
o
E
o
03
0
I
CO
CD
O
E
03
O
O
O
'c/3
JZ
CL
1
^~
cs
o
o
in
i
LO
o
cc
LLJ
I—
LLJ
a
oo
oo
o
<
Q_
CQ
LLJ
a
IT)
LU
_l
m
A Function-Based Framework » May 2012
238
-------
Chapter 11: Application of the Stream Functions Pyramid
2
o
1 —
o
0
o
^_
0
CC
0
1
co
1 1 1
CC
oo
o
Q_
—
o
CC
0 2
oo —
LJJ t
CC Q
LJJ S
CC O
Q_ O
CD
1 —
^f
CC
1 1 1
— 1
CD
—
5
CC
LJJ
— 1
1—
LJJ
+-* 05
si3 05 05 —
O) O) . O) t~ o cc
c c o c +-• c >
'E 'E Z 'E = 2 -o
. 1 1 s 1 1 1 1
•*"' ^ ^ frt ^ ^5 ^~ m
C ^ ^ •— ^ CC 05 2
LU LL LL. CC LL. J2 C2. c/3
05
— •£
> -D 05
-Q 05 E
- = E - = E
i- C/3 >- O) C/3 _c
05 CC 05 c CC 4-1
•£ 05 -fr! •- 05 05
C f— 05 C/3 ,— (—
LU b T3 3 b b
s i O 05 05
O) O) ^ O) JZ 0
c c ^ c +-• c
c c o c S c "P
.2 .2 ^ .2 ° E ro
^oo--oE>2"^ ^
bJ§§4^§cca5
05 -j-j 05
3 05
05 CC C 05 05 -
£ - E - ^ o
^- CC ^- O) C/3 f—
05 3 05 C CC +1
•£ ^ -t-; .± 05 05
C o 05 C/3 /— /—
LU cc "D 3 b b
cl
LJJ -^ TO E O 05
CC a 'C 05 -i-i +-1
=>° 8£5SSg
< h=
LJJ LJJ
CC
LJJ
| —
LJJ
^>
CC
<^
Q_
§^2X^2
-^ O. (— (— 05 ^
O cc b b co ca
ai
>- "~ ^
m* ^j 05 T-i ^
(^ i • 'c ''"' ^
/is cc P CC 05 r"^
uj , ^_ t . | cc
C/3 (^ O >^ 05 -C
£ Q-i CL. CC O
a>
Q •>- —
2 EC o
< 0 I -£
_1 CD >
LJJ LJJ • 33
> H^
1 1 1 <[
_l O <-
_05
Q.
E
CO
X
LU
05
"o.
i
X
LU
05
a.
i
X
LU
05
a.
i
X
LU
05
a.
E
CC
X
LU
_05
Q.
E
CC
X
LU
a>
c
c
o
o
C
^
LL.
O
O)
C
'c
o
ts
o §
"Z. LL.
O
00
g>
'05
i
-* O
c '.p
CO CC
a>
C
C
o
o
C
^
LL.
O
00
O)
C
'c
o
ts
o §
"Z. LL.
^
C
05
E
^
o
C
05 O
-t-* '-P
C CC
LU CC
>.
c •>
CC '-P
— o
Q- 05
•o c
o c
0 0
LL. O
C/3
O
"5
>
i
CM
>.
O)
o
o
JZ
Q.
O
E
o
05
0
I
00
CC
o
E
05
O
O
O
'c/3
Q.
1
•*
cs
o
o
in
i
in
CC
<
Q_
a
LJJ
CC
cq
^
^
LJJ
m
A Function-Based Framework » May 2012
239
-------
Chapter 11: Application of the Stream Functions Pyramid
The next tables (Table 11.7 and 11.8) are templates that can be used to provide sup-
porting text about the above pre- and post-condition tables. On the debit side, the table is
used to describe the pre-disturbance condition and the rationale for selecting the param-
eters and measurement methods. The rationale used to predict the post-impact condition
should also be provided. The approach is similar on the credit side. For this template, a
description of the pre- and post-restoration condition is provided, along with the rationale
for selecting key parameters and measurement methods.
TABLE 11.7 DEBIT TEMPLATE 2: PRE- AND POST-DISTURBANCE CONDITIONS AND RATIONALE
Describe Pre-and Post-Disturbance Condition and Rationale for Selecting Parameters
Enter a short description of the pre- and post-disturbance condition for each functional
category. Explain why the selected parameters and their measurement method were used.
Also include the rationale for the expected outcome. An abbreviated example is provided
below for a permitted culvert installation. The remainder of this example is provided in
Appendix B.
Hydrology: The watershed hydrology is stable and is not expected to change. Therefore,
Hydrology parameters were not selected.
Hydraulic: The existing channel is not incised and has access to a wide alluvial floodplain,
i.e., there is floodplain connectivity. In this example, the culvert will likely cause channel
incision downstream of the culvert, and bank height ratios are likely to increase, causing a
Not Functioning score. The culvert will provide grade control for the upstream channel
and the bank height ratio may decrease because of aggradation.
Geomorphology: see Appendix B, Table B2a
Physicochemical: see Appendix B, Table B2a
Biological: see Appendix B, Table B2a
A Function-Based Framework » May 2012 240
-------
Chapter 11: Application of the Stream Functions Pyramid
TABLE 11.8 CREDIT TEMPLATE 2: PRE- AND POST-RESTORATION CONDITIONS AND RATIONALE
Describe Pre-and Post-Restoration Condition and Rationale for Selecting Parameters
Enter a short description of the pre-and post-restoration condition for each functional
category. Explain why the selected parameters and their measurement method were used,
along with the rationale for the expected improvement. An abbreviated example is
provided below for the restoration of an incised channel. The remainder of this example is
provided in Appendix B.
Hydrology: The watershed hydrology is stable and is not expected to change. Therefore,
Hydrology parameters were not selected.
Hydraulic: The existing channel is severely incised (Bank Height Ratio of 3) and does not
have access to a wide alluvial floodplain. The channel will be reconnected to the
floodplain through a Rosgen Priority 1 Restoration. The Bank Height Ratio will be reduced
to 1.0, and all flows greaterthan bankfull will spread onto a floodplain that is 50 times
wider than the channel, making the entrenchment ratio well over 2.2.
Geomorphology: see Appendix B, Table B11a
Physicochemical: see Appendix B, Table B11a
Biological: see Appendix B, Table B11a
The third set of templates (Tables 11.9 and 11.10) provides debit and credit ratios based
on the results from Template 1. The ratios used to create debits and credits can be modi-
fied. The ones used in this template are for demonstration purposes and were chosen to
encourage mitigation providers to select projects that have the potential for the greatest
functional lift. Credits range from 0 to 1 credit-per-foot of restored channel. Debits range
from 1 to 2 debits-per-foot. Therefore, an impact that creates maximum functional loss
would be assigned 2 debits-per-foot. Since the maximum credit ratio is 1 credit-per-foot,
they will have to perform mitigation on twice the stream length that was impacted. Since
a portion of credits is released before a site reaches maturity, a greater amount of mitiga-
tion is necessary to address this temporal loss as well as the risk of project failure.
Table 11.9 provides example debit ratios. The first column shows the functionality of
the stream reach before an impact occurs. Functionality ranges from Low to High and is
based on the pre-disturbance condition from Debit Template 1. The remaining columns
show the predicted functional loss from the permitted impact, ranging from no function-
al loss to high functional loss, based on the predicted functional loss from Debit Template
1. Debit ratios are then assigned to the different levels of functional loss. Therefore,
high-quality streams that are more severely impacted would yield more debits than
degraded streams that were minimally impacted. A debit adjustment factor is provided
for scenarios that may need to be modified based on unique site conditions or because the
result fits between two categories.
A Function-Based Framework » May 2012 241
-------
Chapter 11: Application of the Stream Functions Pyramid
TABLE 11.9 DEBIT TEMPLATE 3: DEBIT CALCULATIONS
PRE-DISTURBANCE
POST-DISTURBANCE CONDITION
CONDITION
Low (Mix of
Functioning-at-Risk
and Not
Functioning)
Moderate (Mix of
Functioning,
Functioning-at-Risk,
and Not
Functioning)
High (Functioning)
No Functional
Loss
(Post-
disturbance
condition
pre-
disturbance
condition)
No mitigation
required
Low to
Moderate
Functional Loss
Greater number
of Functioning-
at-Risk and Not
Functioning
Scores
1.1 to 1.2
Loss of
Functioning
scores and/or
greater number
of Functioning-
at-Risk and Not
Functioning
Scores
1.3 to 1.5
Mix of
Functioning,
Functioning-at-
Risk, and Not
Functioning
Scores
1.7 to 1.9
Moderate to High
Functional Loss
Mostly Not-
Functioning
Scores
1.2 to 1.3
Mix of
Functioning-at-
Risk and Not
Functioning
Scores
1.5 to 1.7
Mix of
Functioning-at-
Risk and Not
Functioning
Scores
2.0
Debit
Adjustment
0.1
0.1
0.2
Tables 11.10 and 11.11, provide examples of credit determination method templates for
Restoration 1 and Restoration 2 projects. Specific examples are provided in Appendix B.
The table below includes four columns: Credit Category, Pre-Restoration Condition,
Post-Restoration Condition and Credit Ratio. The credit ratio is expressed as credit-per-
foot with the highest ratio set at 1.0 credit-per-foot for a Restoration 1 project with a
Maximum Lift score. Maximum Lift is the first row under the Credit Category. So if a
project was 5,000 feet long, the maximum number of credits that could be attained is
5,000. The other categories are Moderate and Low lift. So a project that has several
Functioning scores in the baseline condition would have a Low lift and would be given
less credit. Note that the post-restoration condition is the same for Maximum, Moderate
and Low lift. The difference is in the baseline condition. This reflects a goal of achieving
the highest restoration or enhancement possible, but acknowledges that some sites start
in a more degraded condition; thus, more lift is created and more credit is given. Again,
these ratios are provided only as a guide. Appendix B provides other examples of credit
determination methods for other scenarios.
A Function-Based Framework » May 2012
242
-------
Chapter 11: Application of the Stream Functions Pyramid
TABLE 11.10 CREDIT TEMPLATE 3: CREDIT CALCULATIONS FOR RESTORATION 1
RESTORATION 1
CREDIT CATEGORIES
PRE-RESTORATION
CONDITION
Maximum Lift
All parameters in Pyramid
Levels 2 and 3 have Not
Functioning scores.
Parameters in Levels 4 and 5
are Not Functioning or
Functioning-at-Risk.
POST-RESTORATION
CONDITION
Functioning scores
for Levels 1-5
CREDITS
PER FOOT
0.8 to 1.0
Moderate Lift
Mix of Not-Functioning and
Functioning-at-Risk scores
for parameter Levels 2
through 5.
Functioning scores
for Levels 1-5
0.6 to 0.8
Low Lift
Mix of Not-Functioning,
Functioning-at-Risk and
Functioning scores for
parameter Levels 2 through 5.
Functioning scores
for Levels 1-5
0.4 to 0.6
Credits = Credit Ratio (in Credits/Ft) times the restored stream length (ft).
TABLE 11.11 CREDIT TEMPLATE 3: CREDIT CALCULATIONS FOR RESTORATION 2
RESTORATION 2
CREDIT CATEGORIES
Maximum Lift
Moderate Lift
Low Lift
PRE-RESTORATION
CONDITION
All parameters in Pyramid
Levels 2 and 3 have Not
Functioning scores.
Mix of Not-Functioning and
Functioning-at-Risk scores
for parameter Levels 2
through 3.
Mostly Functioning-at-Risk
and Functioning scores for
parameter Levels 2 through
3. May include some Not-
Functioning scores.
POST-RESTORATION
CONDITION
Functioning scores
for Levels 1-3
Functioning scores
for Levels 1-3
Functioning scores
for Levels 1-3
CREDITS
PER FOOT
0.6 to 0.8
0.4 to 0.6
0.2 to 0.4
Credits = Credit Ratio (in Credits/Ft) times the restored stream length (ft).
A Function-Based Framework » May 2012
243
-------
Chapter 11: Application of the Stream Functions Pyramid
Enhancement Credits
The Pyramid Framework can be used to help develop enhancement credits, although
less emphasis is placed on these projects within this document. The 2008 Mitigation Rule
defines enhancement as the manipulation of the physical, chemical and biological charac-
teristics of an aquatic resource to heighten, intensify or improve a specific aquatic re-
source function(s). Enhancement may lead to a gain in certain functions, but could also
lead to a decline in other functions. Enhancement does not increase the aquatic resource
area, e.g., stream length. An appropriate way to develop stream enhancement credits
using the Stream Functions Pyramid Framework as a guide is to complete a function-
based assessment before making the determination of whether restoration or enhance-
ment is the better solution. The assessment may be rapid or intensive depending on the
project; however, information about which function-based parameters are Functioning
and Not Functioning must be determined before the practitioner can know what needs
to be enhanced.
Enhancement can lead to projects that achieve the same level of functionality as a
Restoration 1 approach above; however, they can also lead to projects that still have
several function-based parameters with a Functioning-at-Risk or Not Functioning score.
Therefore, the key difference between restoration and enhancement, as described here, is
the level of functional lift. Restoration 1 includes changes to many function-based param-
eters, along with proper site selection, to achieve a fully functioning score. Enhancement
may include a change to only one parameter to achieve a fully functioning score, if all
other key parameters are functioning, e.g., the riparian buffer. In this example, the
product is the same but the amount of functional lift is much less with an enhancement
approach. Enhancement can also improve one function-based parameter like lateral
stability, but not improve other key parameters like floodplain connectivity or bed form
diversity. This would lead to a stream that has some improvement in stream function, but
the change is not necessarily significant. And because the stream is not connected to the
floodplain, the channel could lose other functions in the future.
A table is not provided for calculating enhancement credits. Rather, some examples of
enhancement scenarios are provided below. These examples show how to focus on
enhancements to function-based parameters rather than practices like benching or
in-stream structures. These practices will likely be used; however, the credits should be
based on changes to function-based parameters and not the number of structures. Of
course, enhancement credits should also be less than restoration credits on a per, foot basis.
Example Enhancement Scenarios:
1. Projects in non-incised, rural streams within alluvial valleys. The stream is well
connected to a floodplain and there are diverse bed forms created from the appropri-
ate plan form geometry and bed form complexity. Streambanks are not eroding at
levels above reference conditions, i.e., banks are stable. However, the riparian buffer
is thin with only a single row of trees along the streambank.
A Function-Based Framework » May 2012 244
-------
Chapter 11: Application of the Stream Functions Pyramid
Enhancement credits could be provided for expanding the buffer. In this case,
higher order functions like de-nitrification and even improvements to benthics and
fish may occur — if supported by the upstream watershed.
2. Same setting as number 1 and same conditions, except in addition to having a narrow
riparian buffer, the bed form diversity is also low, e.g., mostly riffle bed forms due to
straightening and vegetation/debris removal.
Enhancement would include improving the bed form diversity, e.g., percent riffle
and pool, depth variability, and improving the buffer width and composition. This
would be a higher level of enhancement because more than one function-based
parameter is being improved.
3. Urban setting, flood control channel. A channelized, trapezoidal channel with
streambanks stabilized by rip rap and some vegetation.
High level of enhancement would include providing limited floodplain connectiv-
ity by excavating bankfull benches, providing bed form diversity through the instal-
lation of in-stream structures, and planting a narrow buffer. Lower-level enhance-
ment would be bank stabilization using vegetation, e.g., bioengineering and perhaps
bed form diversity with in-stream structures; however, significant benching and
vegetation beyond the top of the streambank would be limited.
Example of Calculating Debits and Credits
The following is an example of how the templates can be used to calculate debits and
credits from a hypothetical permitted impact site and a mitigation site.
Impact Site
• 500 feet of culvert with 200 feet of downstream impact and 100 feet of upstream
impact. Total impact length is 800 feet.
• The functional condition before disturbance shows a mix of Not-Functioning, Func-
tioning-at-Risk and Functioning scores for Level 2 through 5 parameters. This equals a
Functionality Before Impact score of Moderate (Table 11.9).
• A standard installation approach is used instead of an arch culvert or bridge, so post-
construction functions will include a greater number of Not-Functioning and Func-
tioning-at-Risk scores for Level 2 through 5 parameters. This equals a Moderate
Functional Loss from Table 11.9.
• A Moderate/Moderate score yields a ratio range of 1.3 to 1.5 debits per foot. For this
example, a ratio of 1.5 is used.
• The total debits equal 1.5 X 800 = 1,200 debits. In other words, 1,200 credits are
needed to compensate for the impacts.
• This example could have been broken into three reaches, including upstream of the
culvert, through the culvert, and downstream of the culvert, since the impacts will
likely vary. An example of calculating debits by reach for a culvert installation is
shown in Appendix B.
A Function-Based Framework » May 2012 245
-------
Chapter 11: Application of the Stream Functions Pyramid
Off-Site Mitigation
• A 10,000-foot stream restoration site is located that meets the Restoration 1 criteria. A
Restoration 1 site includes full restoration of Level 2 and 3 functions and the water-
shed supports Level 4 and 5 functions.
• The pre-restoration condition shows that all parameters in Pyramid Levels 2 and 3
have Not Functioning scores. Parameters in Levels 4 and 5 are Not Functioning or
Functioning-at-Risk.
• The post-restoration condition is predicted to show Functioning scores for Levels 1-5.
The stream is well connected to the floodplain with diverse and complex bed forms
that are representative of the stream type. Riparian buffer is diverse and has sufficient
width to support Level 4 and 5 functions. Since the upstream watershed supports
Level 4 and 5 functions, it is predicted that the project reach will achieve Functioning
scores for Levels 4 and 5 as well.
• This results in a Maximum Lift score, with a credit ratio range of 0.8 to 1.0 credits per foot.
• For this example, a credit ratio of 1.0 is selected.
• The total credits available at this site are 10,000 ft X 1.0 credits/ft = 10,000 credits.
As was mentioned previously, the debits and credits can be modified to meet local condi-
tions and requirements. The debit and credit range selected for these examples was based
on two important factors. First, more credits were provided for scenarios that improved
more functions, i.e., the more functions that are restored, the more credits. Second, a
multiplier is applied to the debits to ensure that debits are never less than the length of
impact. The maximum is 2.2:1, meaning that 2.2 times the amount of impacted length
may be required for mitigation. The multiplier acknowledges the fact that impacts occur
immediately during construction and that mitigation sites take years to reach functional
maturity. Since a portion of credits is released before the site reaches maturity, a greater
amount of mitigation is warranted for temporal losses to stream functions.
11.7 » STEPS TO DEVELOPING DEBITS AND CREDITS
The following provides general steps for using the Pyramid to develop unique debit
and credit determination methods. These steps also provide guidance on how to collect
the information necessary to complete the templates described above. Actual steps and
tasks will vary based on local needs and conditions, and additional steps will be needed
to meet other 2008 Mitigation Rule requirements. For example, the steps below do not
address how to develop the Prospectus or the Mitigation Banking Instrument.
Steps to Develop Debits Using the Pyramid
1. List types of impacts for the service area, i.e., culvert crossings, channelization, etc.
2. Select key function-based parameters from the Pyramid that are typically associated
with each type of impact. The selected parameters should be based on some form of
function-based assessment.
A Function-Based Framework » May 2012 246
-------
Chapter 11: Application of the Stream Functions Pyramid
3. Select the appropriate measurement method for each parameter, e.g., simple and
rapid-based or more complex and time intensive. This selection should be based on
the severity of the impact and difficulty in predicting functional loss.
4. Perform function-based assessment on stream reach proposed to be impacted.
5. Record values for each measurement method and use the performance standards to
determine if the function-based parameter is Functioning, Functioning-at-Risk and
Not Functioning. Record values on Debit Template 1 (Table 11.5).
6. Provide justification for the selection of function-based parameters and measurement
methods in Debit Template 2 (Table 11.6).
7. Develop overall scoring method (optional). Note: This document does not provide a
scoring method that combines parameters, their measurement method and perfor-
mance standard into an overall index of stream function. The document does show a
method for calculating debits without this overall score; however, a function index
might be a helpful tool for future use.
8. Determine overall baseline condition using scoring method developed in step 6, or
refer to the debit calculation method shown in Debit Template 3 (Table 11.9).
9. Calculate overall debits for site. The formula used in this document is the debit ratio
multiplied by the impacted stream length.
Steps to Develop Credits Using the Pyramid
1. Develop or use existing watershed management plans for each service area. Locate
areas of water quality impairment and stream degradation. Determine the causes of
impairment. Also locate areas of high water quality and healthy stream channels.
Use the plan to identify stream reaches that can produce high-quality mitigation and,
if possible, support the overall improvement of the watershed.
2. Based on the watershed management plan, determine the different types of tech-
niques required to improve watershed health, e.g., stormwater BMPs, stream restora-
tion, stream enhancement, riparian corridor preservation.
3. Perform a function-based assessment of the potential project reach.
4. Determine the restoration potential based on the assessment, watershed condition
and constraints.
5. Establish function-based design goals and objectives.
6. Select key parameters from the Pyramid based on the assessment and restoration
potential. Select parameters that are expected to change as a result of the restoration
or enhancement activity.
7. Select the appropriate measurement method for each parameter, e.g., simple and
rapid-based or more complex and time intensive. This selection should be based on
the level of effort required to show functional lift.
8. Record the function-based parameter, measurement method and scores using the
performance standards on Credit Template 1 (Table 11.6).
9. Provide justification for selecting the parameters and measurement methods on Credit
Template 2 (Table 11.8).
A Function-Based Framework » May 2012 247
-------
Chapter 11: Application of the Stream Functions Pyramid
10. Develop overall scoring method (optional). Note: This document does not provide a
scoring method that combines parameters, their measurement method and perfor-
mance standard into an overall index of stream function. The document does show a
method for calculating credits without this overall score; however, a function index
would be a helpful tool for future use.
11. Determine overall baseline condition using scoring method developed in step 10, or
refer to the credit calculation method shown in Tables 11.10 and 11.11.
12. Calculate overall credits predicted for the site. The formula used in this document is
the credit ratio multiplied by the restored or enhanced stream length.
13. Develop a monitoring plan to verify that the functional lift meets or exceeds the
performance standards.
A Function-Based Framework » May 2012 248
-------
References
33 CFR Part 332.3, 2008. Compensatory Mitigation For Losses of Aquatic Resources.
www. nap.usace. army. mil/cenap-op/regulatory/documents/mitigation/33cfr332_ final_ mitig_
rule.pdf
Abbe, T.B., A.P. Brooks, and D.R. Montgomery, 2003. Wood in River Rehabilitation and
Management.
In: The Ecology and Management of Wood in World Rivers, S.V. Gregory, K.L. Boyer,
and A.M. Gurnell (Editors). American Fisheries Society, Bethesda, Maryland, pp.
367-389.
Abbe, T.B. and D.R. Montgomery, 1996. Large Woody Debris Jams, Channel Hydraulics
and Habitat Formation in Large Rivers. Regulated Rivers: Research and Management
12:201-221.
Adams, E.A., S.A. Monroe, A.E. Springer, K.W. Blasch, and D.J. Bills, 2006. Electrical
Resistance Sensors Record Spring Flow Timing, Grand Canyon, Arizona. Ground
Water 44:630-641. doi: 10.1111/j.l745-6584.2006.00223.x.
Albright, LJ. and J.W. Wentworth, 1973. Use of the Heterotrophic Technique as a Mea-
sure of Eutrophication. Environmental Pollution 5:59-72.
Allan, J.D., 2004. Landscapes and Riverscapes: The Influence of Land Use on Stream
Ecosystems. Annual Review of Ecology, Evolution, and Systematics 35:257-284.
Allan, J.D. and M.M. Castillo, 2007. Stream Ecology: Structure and Function of Running
Waters, Second Edition. Springer, Dordrecht, The Netherlands.
Allen, W, T. Weber, E. McLaughlin, and R. Starr, 1999. US 301 Environmental Steward-
ship Methodologies and Results. The Conservation Fund, Maryland Department of
Natural Resources, and US Fish and Wildlife Service, Annapolis, Maryland.
Anderson, K.R., 2011. The Road to Trout Recovery. Presentation, 2011 Mid-Atlantic
Stream Restoration Conference, Rocky Gap Resort, Flintstone, Maryland, www.fws.
gov/chesapeakebay/Masrc/AbstractPDFs.html/anderson2
A Function-Based Framework » May 2012
249
-------
References
Andrews, E.D., 1983. Entrainment of Gravel from Naturally 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 95:371-378.
Andrews, E.D. and D.C. Erman, 1986. Persistence in the Size Distribution of Surficial Bed
Material During an Extreme Snowmelt Flood. Water Resources Research 22(2):191-197
Angermeier P.L. and J.R. Karr, 1986. Applying an Index of Biotic Integrity Based on
Stream-Fish Communities: Considerations in Sampling and Interpretation. North
American Journal of Fisheries Management 6:418-429.
Baattrup-Pedersen, A. and T. Riis, 1999. Macrophyte Diversity and Composition in
Relation to Substratum Characteristics in Regulated and Unregulated Danish Streams.
Freshwater Biology 42:375-385.
Baattrup-Pedersen, A., K. Szoszkiewicz, R. Nijboer, M. O'Hare and T. Ferreira, 2006.
Macrophyte Communities in Unimpacted European Streams: Variability in Assem-
blage Patterns, Abundance and Diversity. Hydrobiologia 566:179-196.
Bagnold, R.A., 1980. An Empirical Correlation of Bedload Transport Rates in Flumes and
Natural Rivers. Proceedings of the Royal Society (London) 372:452-473.
Balon, E.K., 1975. Reproductive Guilds of Fish: A Proposal and Definition. Journal of the
Fisheries Research Board of Canada 32:821-864.
Barbour, M.T., J. Gerritsen, B.D. Snyder and J.B. Stribling, 1999. Rapid Bioassessment
Protocols for Use in Streams and Wadeable Rivers: Periphyton, Benthic Macroinverte-
brates, and Fish, Second Edition, EPA 841-B-99-002. US Environmental Protection
Agency, Washington, DC. http://www.epa.gov/owow/monitoring/rbp/ch07main.html.
Barton D.R., WD. Trylor and R.M. Bierre, 1985. Dimensions of Riparian Buffer Strips
Required to Maintain Trout Habitat in Southern Ontario Streams. North American
Journal of Fishery Management 5:364-378.
Bartsch, A.F. and W.M. Ingram, 1966. Biological Analysis of Water Pollution in North
America. Verhandlungen der Internationalen Vereinigung fur Theoretische und Ange-
wandte 16:786-800.
Benke, A.C., 1984. Secondary Production of Aquatic Insects. In: Ecology of Aquatic Insects,
V.H. Resh and D.M. Rosenberg (Editors). Praeger, New York, New York, pp. 289-322.
A Function-Based Framework » May 2012 250
-------
References
Benke, A., 2010. Secondary Production. Nature Education Knowledge 1(8):5.
Benke, A.C. and C.E. Gushing, 2005. Rivers of North America. Elsevier Academic Press,
Burlington, Massachusetts. ISBN-0-12-088254-1.
Benke A.C. and A.D. Huryn, 2010. Benthic Invertebrate Production — Facilitating An-
swers to Ecological Riddles in Freshwater Ecosystems. Journal of the North American
Benthological Society 29(l):264-285.
Bernhardt, E.S., M.A. Palmer, J.D. Allan, G. Alexander, K. Baranas, S. Brooks, J. Carr, S.
Clayton, C. Dahm, J. Follstad-Shah, D. Galat, S.G. Loss, P. Goodwin, D. Hart, B.
Hassett, R. Jenkinson, S. Katz, G.M. Kondolf, P.S. Lake, R. Lave, J.L. Meyer, T.K.
O'Donnell, L. Pagano, B. Powerll, and E. Sudduth, 2005. Synthesizing US River Resto-
ration Efforts. Science 308:636-637.
Bernot, MJ. and W.K. Dodds, 2005. Nitrogen Retention, Removal and Saturation inLotic
Ecosystems. Ecosystems 8:442-453.
Bevenger, G.S., and R.M. King, 1995. A Pebble Count Procedure for Assessing Watershed
Cumulative Effects. US Department of Agriculture Forest Service Research Paper
RM-RP-319. Rocky Mountain Forest and Range Experiment Station, Fort Collins,
Colorado.
Biggs, B.J.F., 1996. Patterns in Periphyton of Streams. In: Algal Ecology: Freshwater Ben-
thic Ecosystems, RJ. Stevenson, M.L. Bothwell, and R.L. Lowe (Editors). Academic
Press, San Diego, California, pp. 31-56.
Blasch, P.A., T. Ferre, A.H. Christensen and J.P. Hoffman, 2002. New Field Method to
Determine Streamflow Timing Using Electrical Resistance Sensors. Vadose Zone
Journal l(2):289-299.
Bonar, S., W. Hubert and D. Willis, 2009. Standard Methods for Sampling North Ameri-
can Freshwater Fishes. American Fisheries Society, Bethesda, Maryland.
Bond, N.R. and P.S. Lake, 2005. Ecological Restoration and Large-scale Ecological Distur-
bance: The Effects of Drought on the Response by Fish to a Habitat Restoration Ex-
periment. Restoration Ecology 13:39-48.
Bott, T, 1973. Bacteria and the Assessment of Water Quality. In: Biological Methods for
the Assessment of Water Quality, J. Cairns and K.L. Dickson (Editors). American
Society for Testing and Materials, Los Angeles, California.
A Function-Based Framework » May 2012 251
-------
References
Bott, T.L., J.T. Brock, C.E. Gushing, S.V. Gregory, D. King, and R.C. Peterson, 1978. A
Comparison of Methods for Measuring Primary Productivity and Community Respira-
tion in Streams. Hydrobiologia 60:3-12.
Boulton, A.J., T. Datry, T. Kasahara, M. Mutz and J.A. Stanford, 2010. Ecology and Man-
agement of the Hyporheic Zone: Stream-Groundwater Interactions of Running Waters
and Their Floodplains. Journal of North American Benthological Society 29(1):26-40.
doi 10.1899/08-017.1.
Boulton, A.J., S. Findlay, P. Marmonier, E.H. Stanley, and H.M. Valett, 1998. The Func-
tional Significance of the Hyporheic Zone in Streams and Rivers. Annual Review of
Ecology and Systematics 29:59-81.
Bowden, W.B., J.M. Glime, and T. Riis, 2006. Macrophytes and Bryophytes. In: Methods
in Stream Ecology, Second Edition, R.F. Hauer and G.A. Lamberti (Editors). Elsevier,
Oxford, United Kingdom, pp.381-414.
Bridge, J.S., 2003. Rivers and Floodplains: Forms, Processes, and Sedimentary Record.
Blackwell Publishing, Oxford, United Kingdom.
Brunner, G.W., 2010. HEC-RAS Version 4.1 River Analysis System User's Manual. US
Army Corps of Engineers Hydrologic Engineering Center, Davis, California, www.hec.
usace.army.mil/software/hec-ras/hecras-document.html
Bryce S.A., G.A. Lomnicky, P.R. Kaufmann, 2010. Protecting Sediment Sensitive Aquatic
Species in Mountain Streams Through the Application of Biologically Based Streambed
Sediment Criteria. Journal of the North American Benthological Society 29(2):657-672.
Bunte, K. and S.R. Abt, 2001. Sampling Surface and Subsurface Particle-Size Distributions
in Wadeable Gravel- and Cobble-Bed Streams for Analyses in Sediment Transport,
Hydraulics, and Stream-Bed Monitoring. General Technical Report RMRS-GTR-74, US
Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fort
Collins, Colorado.
Cairns, J. and J.R. Pratt, 1993. A History of Biological Monitoring Using Benthic Macroin-
vertebrates. In: Freshwater Biomonitoring and Benthic Macroinvertebrates, D.M.
Rosenberg and V.H. Resh (Editors). Routledge, Chapman, and Hall, New York, New York.
Carle, F.L. and M.R. Strub, 1978. A New Method for Estimating Population Size from
Removal Data. Biometrics 34:621-630.
A Function-Based Framework » May 2012 252
-------
References
Carpenter, S.R., RE Caraco, D.L. Correll, R.W Howarth, A.N. Sharpley and V.H. Smith,
1998. Nonpoint Pollution of Surface Waters with Phosphorus and Nitrogen. Ecological
Applications 8:559-568.
Castelle, A.J., A.W. Johnson and C. Conolly, 1994. Wetland and Stream Buffer Size Re-
quirements — A Review. Journal of Environmental Quality 23:878-882.
Castro, J.M. and P.L. Jackson, 2001. Bankfull Discharge Recurrence Intervals and Regional
Hydraulic Geometry Relationships: Patterns in the Pacific Northwest, USA. Journal of
the American Water Resources Association 37(5):1249-1262.
Chaplin, J.J., 2005. Development of Regional Curves Relating Bankfull-Channel Geom-
etry and Discharge to Drainage Area for Streams in Pennsylvania and Selected Areas
of Maryland. US Geological Survey Water-Resources Investigation Report 2005-5147,
US Geological Survey, Reston, Virginia.
Chin, A., 1989. Step Pools in Stream Channels. Progress in Physical Geography 13:391-407
Clarke, S.J., 2002. Vegetation Growth in Rivers: Influences Upon Sediment and Nutrient
Dynamics. Progress in Physical Geography 26:159-172.
Claussen, J.C., K. Guillard, C.M. Sigmund and K.M. Dors, 2000. Water Quality Changes
From Riparian Buffer Restoration in Connecticut. Journal of Environmental Quality
29:1751-1761.
Clean Water Act (CWA), 2002. 33 U.S.C. 1251 et seq. http://epw.senate.gov/water.pdf
Cinotto, P.J., 2003. Development of Regional Curves of Bankfull-Channel Geometry and
Discharge for Streams in Non-Urban, Piedmont Physiographic Province, Pennsylvania
and Marlyand. US Geological Survey Investigation Report 03-4014, US Geological
Survey, Reston, Virginia.
Cooper, J.R., J.W. Gilliam, R.B. Daniels and WP. Robarge, 1987. Riparian Areas as Filters
in Agricultural Sediment. Soil Science Society of America Journal 51:416-420.
Cronk, J.K. and M.S. Fennessy, 2001. Wetland Plants: Biology and Ecology. CRC Press/
Lewis Publishers, Boca Raton, Florida.
Cummins, K.W., 1973. Trophic Relations of Aquatic Insects. Annual Review of Entomol-
ogy 18:183-206.
A Function-Based Framework » May 2012 253
-------
References
Cummins, K.W. and MJ. Klug, 1979. Feeding Ecology of Stream Invertebrates. Annual
Review of Ecology and Systematics 10:147-172.
Cummins, K.W., J.R. Sedell, EJ. Swanson, G.W. Minshall, S.G. Fisher, C.E. Gushing, R.C.
Peterson and R.L. Vannote, 1983. Organic Matter Budgets for Stream Ecosystems. In:
Stream Ecology: Application and Testing of General Ecological Theory, J.R. Barnes and
G.W. Minshall (Editors). Plenum Press, New York, New York, pp. 299-253.
Dahm, C.N., M.A. Baker, D.I. Moore and J.R. Thibault, 2003. Coupled Biogeochemical
and Hydrological Responses of Streams and Rivers to Drought. Freshwater Biology
48:1219-1231.
Daniels, R.B. and J.W. Gilliam, 1996. Sediment and Chemical Load Reduction by Grass
and Riparian Filters. Soil Science Society of America Journal 60(1):246-251.
Darby, S.E. and C.R. Thornes, 1992. Impact of Channelisation on the Mimmshall Brook,
Hertfordshire, UK. Regulated Rivers 7:193-204.
Davis, W.M., 1899. The Geographical Cycle. Geographical Journal 14:481-504.
Davis, J.C., W.G. Minshall, CT. Robinson and P. Landres, 2001. Monitoring Wilderness
Stream Ecosystems. General Technical Report RMRS-GTR-70. US Department of
Agriculture, Forest Service, Rocky Mountain Research Station, Fort Collins, Colorado.
Dawson, H., 2002. Guidance for the Field Assessment of Macrophytes of Rivers within
the STAR Project. National Environment Research Council, Centre for Ecology and
Hydrology, Dorset, United Kingdom.
Dingman. L.S., 2008. Physical Hydrology, Second Edition. Prentice Hall, New York, New York.
Dodds, W.K., and J. Brock, 1998. A Portable Flow Chamber for In Situ Determination of
Benthic Metabolism. Freshwater Biology 39:49-59.
Doll, B.A., D.E. Wise-Frederick, C.M. Buckner, S.D. Wilkerson, WA. Harman, R.E.
Smith, and J. Spooner, 2002. Hydraulic Geometry Relationships for Urban Streams
throughout the Piedmont of North Carolina. Journal of the American Water Resources
Association 38:641-651.
Dolloff, C.A. and M.L.Warren, Jr., 2003. Fish Relationships with Large Wood in Small
Streams. American Fisheries Society Symposium 37:179-193.
A Function-Based Framework » May 2012 254
-------
References
Downing, ]., and EH. Rigler, 1984. Secondary Productivity in Fresh Waters. Blackwell,
New York, New York.
Dudley, R.W., 2004. Hydraulic-Geometry Relations for Rivers in Coastal and Central
Maine. US Geological Survey Water-Resources Investigation Report 2004-5042, US
Geological Survey, Reston, Virginia.
Dunne, T. and L.B. Leopold, 1978. Water in Environmental Planning. WH. Freeman Co.,
San Francisco, California.
Dutnell, R.C., 2000. Development of Bankfull Discharge and Channel Geometry Rela-
tionships for Natural Channel Design in Oklahoma Using a Fluvial Geomorphic
Approach. Master's Thesis, University of Oklahoma, Norman, Oklahoma.
Easterbrook, D.J., 1999. Surface Processes and Landforms, Second Edition. Prentice-Hall,
Inc., Upper Saddle Brook, New Jersey.
Eaton, A.D., L.S. Clesceri, E.W. Rice and A.E. Greenberg, 2005. Standard Methods for the
Examination of Water and Wastewater, 21st Edition. American Public Health Associa-
tion, Washington, D.C.
Edwards, R.T., J.L. Meyer, and S.E.G. Findlay, 1990. The Relative Contribution of Benthic
and Suspended Bacteria to System Biomass, Production, and Metabolism in a Low-
Gradient Blackwater River. Journal of the North American Benthological Society
9(3):216-228.
Ehrman, T.P. and G.A. Lamberti, 1992. Hydraulic and Particulate Matter Retention in a
3rd Order Indiana Stream. Journal of the North American Benthological Society
11:341-349.
Eiler, J.H., 1995. A Remote Satellite-Linked Tracking System for Studying Pacific Salmon
with Radio Telemetry. Transactions of the American Fisheries Society 124(2):184-193.
Endreny, T.A., 2003. Fluvial Geomorphology Module. University Corporation for Atmo-
spheric Research (UCAR) COMET Program and National Oceanic and Atmospheric
Administration (NOAA) River Forecast Center, Syracuse, New York, www.fgmorph.com.
Engel, S.R. and J.R. Voshell, 2002. Volunteer Biological Monitoring: Can It Accurately
Assess the Ecological Condition of Streams? American Entomologist 48:164-177.
Essington, M.E., 2004. Soil and Water Chemistry: An Integrative Approach. CRC Press,
LLC, Boca Raton, Florida.
A Function-Based Framework » May 2012 255
-------
References
European Commission, 2000. Directive 2000/60/EC of the European Parliament and of
the Council — Establishing a Framework for Community Action in the Field of Water
Policy. Brussels, Belgium.
Federal Interagency Stream Restoration Working Group (FISRWG). 1998. Stream Corridor
Restoration: Principles, Processes and Practices. National Technical Information Ser-
vice, Springfield, Virginia.
Federal Water Pollution Control Act of 1972 (FWPCA, 1972) Public Law 92-500, 86 Stat.
816. Amended in 1977 and 1987, referred to as the Clean Water Act, codified at 33
U.S.C. 1251-1387 (1988)
Ferreira, M.T., A. Albuquerque, F.C. Aguiar and N. Sidorkewicz, 2002. Assessing Refer-
ence Sites and Ecological Quality of River Plant Assemblages from an Iberian Basin
Using a Multivariate Approach. Archive fur Hydrobiologie 155:121-145.
Fetter, C.W., 1994. Applied Hydrogeology Macmillan College Publishing Company. New
York, New York.
FinlayJ.C., 2001. Stable-Carbon-Isotope Ratios of River Biota: Implications for Energy
Flow inLotic Food Webs. Ecology 82:1052-1064.
Fischenich, C. and R. Seal, 1999. Boulder Clusters. EMRRP Technical Notes Collection
(ERDC TN-EMRRP-SR-11), US Army Engineer Research and Development Center,
Vicksburg, Mississippi. http://libweb.erdc.usace.army.mil/Archimages/7431.PDF.
Fischenich, J.C., 2006. Functional Objectives for Stream Restoration, EMRRP Technical
Notes Collection (ERDC TN-EMRRP-SR-52), US Army Engineer Research and Devel-
opment Center, Vicksburg, Mississippi, http://el.erdc.usace.army.mil/elpubs/pdf/sr52.pdf.
Fischer, R.A., C.O. Martin, J.T. Ratti and J. Guidice, 2000. Riparian Terminology: Confu-
sion and Clarification. EMRRP Technical Notes Collection (ERDC TN-EMRRP-SR-
25), US Army Engineer Research and Development Center, Vicksburg, Mississippi.
http://www. wes. army, mil/el/emrrp.
Fischer, R.A. and J.C. Fischenich, 2000. Design Recommendations for Riparian Corridors
and Vegetated Buffer Strips. EMRRP Technical Notes Collection (ERDC TN-EMRRP-
SR-24), US Army Engineer Research and Development Center, Vicksburg, Mississippi.
http://www. wes. army, mil/el/emrrp.
Fisher, S.G., N.B. Grimm, E. Marti', R.M. Holmes and J.B. Jones, Jr., 1998. Material Spiral-
ing in Stream Corridors: A Telescoping Ecosystem Model. Ecosystems 1:19-34.
A Function-Based Framework » May 2012 256
-------
References
Fore, L.S., 2003. Response of Diatom Assemblages to Human Disturbance: Development
and Testing of a Multimetric Index for the Mid-Atlantic Region (USA). In: Biological
Response Signatures, Indicator Patterns Using Aquatic Communities, T.P. Simon
(Editor). CRC Press, Boca Raton, Florida, pp. 445-471.
Fore, L.S. and C. Grafe, 2002. Using Diatoms to Assess the Biological Condition of Large
Rivers in Idaho (USA). Freshwater Biology 47:2015-2037.
Flores, H., D. McMonigle, and K. Underwood, 2011. Regenerative Step Pool Storm Con-
veyance (SPSC) Design Guidelines, Revision 4. Department of Public Works, Anne
Arundel County Government, Maryland. http://www.aacounty.org/DPW/Watershed/
SPSCdesignguidelinesJan2012rev4.pdf
Fritz, K.M., B.R. Johnson and D.M. Walters, 2006. Field Operations Manual for Assessing
the Hydrologic Permanence and Ecological Condition of Headwater Streams. EPA
600/R-06/126, US Environmental Protection Agency, Washington, DC 20460..
Georgia Department of Transportation (GDOT), 2004. Final Report: Regional Curve
Development for the Coastal Plain of Georgia. Buck Engineering, Gary, North Carolina.
Gerhard, M. and M. Reich, 2000. Restoration of Streams with Large Wood: Effects of
Accumulated and Built-in Wood on Channel Morphology, Habitat Diversity and
Aquatic Fauna. International Revue of Hydrobiology 85:123-137
Gomez, B., 1991. Bedload Transport. Earth-Science Reviews 31(2):89-132.
Gordon, N.D., T.A. McMahon, B.L. Finlayson, C.J. Gippel, R.J. Nathan, 2004. Stream
Hydrology: An Introduction for Ecologists, Second Edition. John Wiley and Sons,
Hoboken, New Jersey.
Goulsbra, C.S., J.B. Lindsay and M.G. Evans, 2009. A New Approach to the Application of
Electrical Resistance Sensors to Measuring the Onset of Ephemeral Streamflow in Wet-
land Environments. Water Resources Research 45(W09501):l-7
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 Society
of America Bulletin 102: 340-352.
Gregory, K.J., A.M. Gurnell, C.T. Hill and S. Tooth, 1994. Stability of the Pool-riffle
Sequence in Changing River Channels. Regulated Rivers: Research and Management
9:35-43.
A Function-Based Framework » May 2012 257
-------
References
Gregory, S.V., FJ. Swanson, W.A. McKee and K.W. Cummins, 1991. An Ecosystem Per-
spective of Riparian Zones: Focus on Links between Land and Water. Bioscience
41:540-551.
Giicker, B. and M.T. Pusch, 2006. Regulation of Nutrient Uptake in Eutrophic Lowland
Streams. Limnology and Oceanography 51(3):1443-1453.
Hack, J.T., 1960. Interpretations of Erosional Topography in Humid Temperate Regions.
American Journal of Science 258A:80-97.
Hammer, T, 1972. Stream Channel Enlargement Due to Urbanization. Water Resources
Research 8(6):1530-1540.
Harman, W.A., 2008. Design Improvements of Meander Bend Protection Using Root
Wads. Southeastern Regional Conference on Stream Restoration, Winston-Salem, NC
Harman, W.A., 2009. The Functional Lift Pyramid (Presentation). Mid-Atlantic Stream
Restoration Conference, Morgantown, WV. www.canaanvi.org/canaanvi_web/uploaded-
Files/Events/Past_Events/masrcl_harman_will.pdf.
Harman, W.A., G.D. Jennings, J.M. Patterson, D.R. Clinton, L.O. Slate, A.G. Jessup, J.R.
Everhart and R.E. Smith, 1999. Bankfull Hydraulic Geometry Relationships for North
Carolina Streams. In: American Water Resources Association Wildland Hydrology
Proceedings, TPS-99-3, D.S. Olsen and J.P. Potyondy (Editors). American Water Re-
sources Association, Middleburg, Virginia, pp. 401-408.
Harman, W.A. and R. Starr, 2011. Natural Channel Design Review Checklist. US Fish and
Wildlife Service, Chesapeake Field Office, Annapolis, MD. US Environmental Protec-
tion Agency, Office of Wetlands, Oceans and Watersheds, Wetlands Division, Wash-
ington, DC. EPA 843-B-12-005.
Harman, W.A., D.E. Wise, M.A. Walker, R. Morris, M.A. Cantrell, M. Clemmons, G.D.
Jennings, D. Clinton and J. Patterson, 2000. Bankfull Regional Curves for North Carolina
Mountain Streams. In: Proceedings of the American Water Resources Association
Conference Water Resources in Extreme Environments, Anchorage, Alaska, D.L. Kane
(Editor). American Water Resources Association, Middleburg, Virginia, pp. 185-190.
Harrelson, C.C., C.L. Rawlins and J.P. Potyondy, 1994. Stream Channel Reference Sites:
An Illustrated Guide to Field Technique. General Technical Report RM-245. US De-
partment of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment
Station, Fort Collins, Colorado.
A Function-Based Framework » May 2012 258
-------
References
Harvey, J.W. and K.E. Bencala, 1993. The Effect of Streambed Topography on Surface-
Subsurface Water Exchange in Mountain Catchments. Water Resources Research
29:89-98.
Haslam, S.; 1987. River Plants of Western Europe. Cambridge University Press, Cam-
bridge, United Kingdom.
Hauer, F.R. and W.R. Hill, 2006. Temperature, Light and Oxygen. In: Methods in Stream
Ecology, Second Edition, F.R. Hauer and G.A. Lamberti (Editors). Elsevier, Amsterdam,
The Netherlands, pp. 103-117.
Haury,}., M.C., Peltre, M. Tremolieres and J. Barbe, G. Thiebaut, I. Bernez, H. Daniel, P.
Chatenet, G. Haan-Archipof, S. Muller, A. Dutartre, C. Laplace-Trey ture, A. Cazau-
bon, E. Lambert-Servien, 2006. A New Method Involving Macrophytes to Assess
Water Trophy and Organic Pollution: The Macrophyte Biological Index for Rivers
(IBMR) — Application to Different Types of Rivers and Pollutions. Hydrobiologia
570(1):153-158.
Hendricks, S.P., 1993. Microbial Ecology of the Hyporheic Zone: A Perspective Integrating
Hydrology and Biology. Journal of the North American Benthological Society 12:70-78.
Hession, W.C., T.E. Johnson, D.E Charles, D.D. Hart, R.J. Horwitz, D.A. Kreeger, J.E.
Pizutto, DJ. Velinsky, J.D. Newbold, C. Cianfrani, T Clason, A.M. Compton, N.
Coulter, L. Fuselier,B.D. Marshall, and J. Reed, 2000. Ecological Benefits of Riparian
Reforestation in Urban Watersheds: Study Design and Preliminary Results. Environ-
mental Monitoring and Assessment63:211-222.
Hey, R.D., 2006. Fluvial Geomorphological Methodology for Natural Stable Channel
Design. Journal of American Water Resources Association 42 (2): 357-374.
Hill, B.H. and AT. Herlihy, 2000. Periphyton (Section 7). In: Environmental Monitoring
and Assessment Program—Surface Waters: Field Operations and Methods Manual for
Measuring the Ecological Condition of Wadeable Streams, J.M. Lazorchak, B.H. Hill,
D.K. Averill, D.V. Peck, and DJ. Klemm (Editors). US Environmental Protection Ser-
vice, Cincinnati, Ohio, http://www.epa.gov/emap/html/pubs/docs/groupdocs/surfwatr/
field/R5_ remap.pdf
Hill, B.H., AT. Herlihy, P.R. Kaufmann, J.R. Stevenson, F.H. McCormick, and C.B. John-
son, 2000. Use of Periphyton Assemblage Data as an Index of Biotic Integrity. Journal
of the North American Benthological Society 19:50-67
A Function-Based Framework » May 2012 259
-------
References
Hilsenhoff, W.L., 1988. Rapid Field Assessment of Organic Pollution with a Family-Level
Biotic Index. Journal of the North American Benthological Society 7:65-68.
Hobbie, J.E. and R.T. Wright, 1965. Bioassay with Bacterial Uptake Kinetics: Glucose in
Freshwater. Limnology and Oceanography 10:471-474.
Hoffman, J.C., 2006. Do American Shad Grow on Trees? Linking Forests with the Life
History of a Marine Fish. Fisheries 31(2):94.
Holmes, N., T.H., J. R. Newman, S. Chadd, K.J. Rouen, L. Saint, and F.H. Dawson, 1999.
Mean Trophic Rank: A Users Manual, R&D Technical Report E38. Environment
Agency of England and Wales, Bristol, United Kingdom.
Hughes, R.M., AT. Herlihy, and P.R. Kaufmann, 2010. An Evaluation of Qualitative
Indexes of Physical Habitat Applied to Agricultural Streams in Ten US States. Journal
of the American Water Resources Association 46(4):792-806.
Humphries, P. and D.S. Baldwin, 2003. Drought and Aquatic Ecosystems: An Introduc-
tion. Freshwater Biology 48:1141-1146.
Hupp, C.R., 1992. Riparian Vegetation Recovery Patterns Following Stream Channeliza-
tion: A Geomorphic Perspective. Ecology 73:1209-1226.
Hynes, H.B.N., 1960. Biology of Polluted Waters. Liverpool University Press, Liverpool,
United Kingdom.
Hynes, H.B.N., 1970. The Ecology of Running Water. University of Toronto Press, Toron-
to, Canada.
Inglis, C.C., 1947 Meanders and their Bearing on River Training. Institution of Civil Engi-
neers, Maritime and Waterways Engineering Division, Paper No. 7, London, England.
Jackson D.A., P.R. Peres-Neto, and J.D. Olden, 2001. What Controls Who is Where in
Freshwater Fish Communities — The Roles of Biotic, Abiotic, and Spatial Factors.
Canadian Journal of Fisheries and Aquatic Sciences 58:157-170.
Jackson J.K. and V.H. Resh, 1989. Activities and Ecological Role of Adult Aquatic Insects
in the Riparian Zone of Streams. In: Proceedings of the California Riparian Systems
Conference: protection, management, and restoration for the 1990s, Davis, California,
D.L. Abell (Editor). General Technical Report PSW-110, US Department of Agriculture,
Forest Service, Pacific Southwest Forest and Range Experiment Station, Berkeley,
California, pp. 342-346.
A Function-Based Framework » May 2012 260
-------
References
James, A.B.W. and I.M. Henderson, 2005. Comparison of Coarse Particulate Organic
Matter Retention in Meandering and Straightened Sections of a Third-order New
Zealand Stream. River Research and Applications 21:641-650.
Janauer, G. and M. Dokulil, 2006. Macrophytes and Algae in Running Waters. In: Biologi-
cal Monitoring of Rivers: Applications and Perspectives, G.M. Ziglio, M. Siligardi and
G. Flaim (Editors). John Wiley & Sons, Ltd, Chichester, United Kingdom, pp. 89-109.
Kalbus, E., F. Reinstorf and M. Schirmer, 2006. Measuring Methods for Groundwater,
Surface Water and Their Interactions: A Review. Hydrology and Earth System Sciences
Discussion 3(4):1809-1850.
Kappesser, G.B., 2002. A Riffle Stability Index to Evaluate Sediment Loading to Streams.
Journal of the American Water Resources Association 38(4):1069-1081.
Karr, J.R., 1993. Defining and Assessing Ecological Integrity Beyond Water Quality.
Environmental Toxicology and Chemistry 12(9):1521-1531.
Karr, J.R., K.D. Fausch, P.L. Angermeier, P.R. Yant, and IJ. Schlosser, 1986. Assessing
Biological Integrity of Running Waters: A Method and its Rationale. Illinois Natural
History Survey, Special Publication #5, Champaign, Illinois.
Kasahara, T and A.R. Hill, 2006. Hyporheic Exchange Flows Induced by Constructed
Riffles and Steps in Lowland Streams in Southern Ontario, Canada. Hydrological
Processes 20(20):4287-4305.
Kasahara, T. and A.R. Hill, 2007. Instream Restoration: Its Effects on Lateral Stream-Sub-
surface Water Exchange in Urban and Agricultural Streams in Southern Ontario. River
Research and Applications 23:801-814.
Keaton, J.N., T. Messinger and E.J. Doheny, 2005. Development and Analysis of Regional
Curves for Streams in the Non-Urban Valley and Ridge Physiographic Province, Mary-
land, Virginia, and West Virginia. US Geological Survey Water-Resources Investigation
Report 2005-5076, US Geological Survey, Reston, Virginia.
Kilpatrick, F.A. and H.H. Barnes Jr., 1964. Channel Geometry of Piedmont Streams as
Related to Frequency of Floods. US Geological Survey Professional Paper 422-E, US
Geological Survey, Reston, VA.
A Function-Based Framework » May 2012 261
-------
References
Klemm, D.J., J. M. Lazorchak and D.V. Peck, 2000. Benthic Macroinvertebrates (Section
9). In: Environmental Monitoring and Assessment Program—Surface Waters: Field
Operations and Methods Manual for Measuring the Ecological Condition of Wadeable
Streams, J.M. Lazorchak, B.H. Hill, O.K. Averill, D.V. Peck, and D.J. Klemm (Editors).
US Environmental Protection Service, Cincinnati, Ohio, pp. 146-160. www.epa.gov/
emap/html/pubs/docs/groupdocs/surfwatr/field/R5_remap.pdf
Klocker, C.A., S.S. Kaushal, P.M. Groffman, P.M. Mayer and R.P. Morgan, 2009. Nitrogen
Uptake and Denitrification in Restored and Unrestored Streams in Urban Maryland,
USA. Aquatic Science 71:411-424.
Knight, A.W. and R.L. Bottorff, 1984. The Importance of Riparian Vegetation to Stream
Ecosystems. In: California Riparian Systems, Ecology, Conservation, and Productive
Management, R.E. Warner and K.M. Hendrix (Editors). Univeristy of California Press,
Berkeley, California, pp. 160-167.
Knighton, D., 1998. Fluvial Forms and Processes: A New Perspective. Oxford University
Press Inc., New York, New York.
Kroes, D.E. and C.R. Hupp, 2010. The Effect of Channelization on Floodplain Sediment
Deposition and Subsidence Along the Pocomoke River, Maryland. Journal of the
American Water Resources Association 46(4):686-699.
Kuehne, R.A., 1962. A Classification of Streams, Illustrated by Fish Distribution in an
Eastern Kentucky Creek. Ecology 43(4):608-614.
Lake, P.S., N. Bond and P. Reich, 2007. Linking Ecological Theory with Stream Restora-
tion. Freshwater Biology, 52:597-615.
Lamberti, G.A., 1996. The Role of Periphyton in Benthic Food Webs. In: Algal Ecology:
Freshwater Benthic Ecosystems, RJ. Stevenson, M.L. Bothwell, and R.L. Lowe (Edi-
tors). Academic Press, San Diego, California, pp. 533-572.
Lamberti, G.A., J.W. Feminella, and C.M. Pringle, 2006. Primary Producer-Consumer
Interactions. In: Methods in Stream Ecology, Second Edition, R.F. Hauer and G.A.
Lamberti (Editors). Elsevier, Oxford, United Kingdom, pp. 537-559.
Lamberti, G.A. and S.V Gregory, 2006. CPOM Transport, Retention, and Measurement.
In: Methods in Stream Ecology, Second Edition, R.F. Hauer and G.A. Lamberti (Edi-
tors). Elsevier, Oxford, United Kingdom, pp. 273-289.
A Function-Based Framework » May 2012 262
-------
References
Langbein, W.B. and L.B. Leopold, 1966. River Meanders — Theory of Minimum Vari-
ance. United States Geological Survey Professional Paper 422H, US Geological Survey,
Reston, VA.
Lane, E.W., 1955. Design of Stable Channels. Transactions of the American Society of
Civil Engineers Paper No. 2776:1234-1279.
Lane, E.W., 1955. The Importance of Fluvial Morphology in Hydraulic Engineering.
Proceedings of the American Society of Civil Engineering 81(745):1-17
Lee, M.T., R.K. Peet, S.D. Roberts, and T.R. Wentworth, 2008. CVS-EEP Protocol for
Recording Vegetation, Version 4.2. North Carolina Department of Environment and
Natural Resources, Ecosystem Enhancement Program, Raleigh, North Carolina.
Lee, K.H., T.M. Isenhart, and R.C. Schultz, 2003. Sediment and Nutrient Removal in an
Established Multi- Species Riparian Buffer. Soil and Water Conservation Journal
Leopold, L.B., 1994. A View of the River. Harvard University Press, Cambridge,
Massachusetts.
Leopold, L.B. and M.G. Wolman, 1957. River Channel Patterns: Braided, Meandering and
Straight. US Geological Survey Professional Paper 282B: 39-103.
Leopold, L.B., M.G. Wolman and J.P. Miller, 1964. Fluvial Processes in Geomorphology
W.H. Freeman and Co., San Francisco, California.
Leopold, L.B., M.G. Wolman and J.P. Miller, 1992. Fluvial Processes in Geomorphology.
Dover Publications, Inc., New York, New York.
Lowe, R.L., and G.D. LaLiberte, 2006. Benthic Stream Algae: Distribution and Structure.
In: Methods in Stream Ecology, Second Edition, R.F. Hauer and G.A. Lamberti (Edi-
tors). Elsevier, Oxford, United Kingdom, pp. 327-356.
Lowrance, R. and J.M. Sheridan, 2005. Surface Runoff Quality in a Managed Three Zone
Riparian Buffer. Journal of Environmental Quality 34(5):1851-1859.
Lowrance, R.R., R.L. Todd, J. Fail, O. Hendrickson, R. Leonard, and L.E. Asmussen, 1984.
Riparian Forests as Nutrient Filters in Agricultural Watersheds. Bioscience 34:374-377
A Function-Based Framework » May 2012 263
-------
References
Magette, W.L., R.B. Brinsfield, R.E. Palmer, and J.D. Wood, 1989. Nutrient and Sediment
Removal by Vegetated Filter Strips. Transactions, American Society of Agricultural
Engineers 32:663-667.
Malison, R.L., J.R. Benjamin, and C.V. Baxter, 2010. Measuring Adult Insect Emergence
from Streams: The Influence of Trap Placement and a Comparison with Benthic
Sampling. Journal of the North American Benthological Society 29(2): 647-656.
Mandaville, S.M., 2002. Benthic Macroinvertebrates in Freshwaters— Taxa Tolerance Val-
ues, Metrics, and Protocols, Project H-l. Soil & Water Conservation Society of Metro
Halifax, Nova Scotia.
Matthews, R.A., A.L. Buikema, Jr., J. Cairns, Jr., and J.H. Rodgers, Jr., 1982. Biological
Monitoring Part IIA — Receiving System Functional Methods, Relationships, and
Indices. Water Resources 16: 129-139.
Mayer, P.M., S.K. Reynolds, M.D. McCutchen, and T.J. Canfield, 2006. Riparian Buffer
Width, Vegetative Cover, and Nitrogen Removal Effectiveness: A Review of Current
Science and Regulations. US Environmental Protection Agency EPA/600/R-05/118,
Washington, D.C. http://www.epa.gov/nrml/pubs/600R05118
McCafferty, P.W., 1981. Aquatic Entomonology The Fishermen's and Ecologists' Illustrat-
ed Guide to Insects and their Relatives. Jones and Bartlett Publishers, Boston, Massachusetts.
McCandless, T.L. and R.A. Everett, 2002. Maryland Stream Survey: Bankfull Discharge
and Channel Characteristics of Streams in the Piedmont Hydrologic Region. US Fish
and Wildlife Service Technical Report CBFO-S02-01, US Fish and Wildlife Service,
Chesapeake Bay Field Office, Annapolis, Maryland.
McCandless, T.L., 2003a. Maryland Stream Survey: Bankfull Discharge and Channel
Characteristics of Streams in the Allegheny Plateau and the Valley and Ridge Hydro-
logic Regions. US Fish and Wildlife Service Technical Report CBFO-S03-01, US Fish
and Wildlife Service, Chesapeake Bay Field Office, Annapolis, Maryland.
McCandless, T.L., 2003b. Maryland Stream Survey: Bankfull Discharge and Channel
Characteristics in the Coastal Plain Hydrologic Region. US Fish and Wildlife Service
Technical Report CBFO-S03-02, US Fish and Wildlife Service, Chesapeake Bay Field
Office, Annapolis, Maryland.
McCormick, F.H., R.M. Hughes, P.R. Kaufmann, AT. Herlihy, and D.V Peck, 2001.
Development of an Index of Biotic Integrity for the Mid-Atlantic Highlands Region.
Transactions of the American Fisheries Society 130:857-877
A Function-Based Framework » May 2012 264
-------
References
McKay, K., I. Linkov, C. Fischenich, S. Miller, and J. Valverde, 2012. Ecosystem Restora-
tion Objectives and Metrics (In Progress). EBA Technical Notes Collection, ERDC
TN-EMRRP-EBA-12-##. US Army Engineer Research and Development Center,
Vicksburg, Mississippi.
Meilinger, P., S. Schneider, and A. Melzer, 2005. The Reference Index Method for the
Macrophyte-Based Assessment of Rivers — a Contribution to the Implementation of
the European Water Framework Directive in Germany. International Review of Hydro-
biology 90(3):322-342.
Merigliano, M.F., 1997. Hydraulic Geometry and Stream Channel Behavior: An Uncertain
Link. Journal of the American Water Resources Association 33(6):1327-1336.
Merritt, R.W and K.W Cummins, 1996. An Introduction to the Aquatic Insects of North
America, Third Edition. Kendall/Hunt Publishing Company, Dubuque, Iowa. ISBN-13:
978-0787232412.
Messinger, T, 2003. Comparison of Storm Response of Streams in Small, Unmined and
Valley-Filled Watersheds, 1999-2001, Ballard Fork, West Virginia. US Geological Survey
Water-Resource Investigations Report 02-4303, US Geological Survey, Reston, Virginia.
Metcalf, C.K., 2004. Regional Channel Charateristics for Maintaining Natural Fluvial
Geomorphology in Florida Streams. US Fish and Wildlife Service Technical Report, US
Fish and Wildlife Service Panama City Fisheries Resource Office, Panama City, Florida.
Meybeck, M., 1982. Carbon, Nitrogen and Phosphorus Transport by World Rivers. Ameri-
can Journal of Science 282:401-450.
Miller, SJ. and D. Davis, 2003. Identifying and Optimizing Regional Relationships for
Bankfull Discharge and Hydraulic Geometry at USGS Stream Gage Sites in the
Catskill Mountains, New York. Technical Report, New York City Department of
Environmental Protection, New York, New York.
Miller, S.J., B.A. Pruitt, C.H. Theiling , J.C. Fischenich and S.B. Komlos, 2011. Reference
Concepts in Ecosystem Restoration and EBA: Principles and Practices, EBA Technical
Notes Collection, ERDC TN-EMRRP-EBA-ll-##. US Army Engineer Research and
Development Center, Vicksburg, Mississippi, cw-environment.usace.army.mil/eba
Minshall, G.W., K.W. Cummins, R.C. Peterson, C.E. Gushing, D.A. Bruns, J.R. Sedell, and
R.L. Vannote, 1985. Developments in Stream Ecosystem Theory. Canadian Journal
Fisheries and Aquatic Sciences 42:1045-1055.
A Function-Based Framework » May 2012 265
-------
References
Moerke, A.H. and G.A. Lamberti, 2003. Response in Fish Community Structure to
Restoration of Two Indiana Streams. North American Journal of Fisheries Manage-
ment 23:748-759.
Montgomery, D.R. and J.M. Buffington, 1993. Channel Classification, Prediction of
Channel Response, and Assessment of Channel Condition, TFW-SH10-93-002, Tim-
ber, Fish, and Wildlife Agreement. Washington Department of Natural Resources,
Olympia, Washington.
Montgomery, D.R., B.D. Collins, J.M Buffington, and T.B. Abbe, 2003. Geomorphic
effects of wood in rivers, In: The Ecology and Management of Wood in World Rivers,
S.V. Gregory, K.L. Boyer, and A.M. Gurnell (Editors). American Fisheries Society
Symposium, Bethesda, Maryland, pp. 21-47
Mortimer, C.H., 1981. The Oxygen Content of Air-Saturated Fresh Waters over Ranges of
Temperature and Atmospheric Pressure of Limnological Interest. Mitteilungen der IVL
22:1-23.
Moyle, P.B. and JJ. Cech, Jr., 1982. Fishes: An Introduction to Ichthyology. Prentice Hall,
Englewood Cliffs, New Jersey.
Mullner, S.A., W.A. Hubert, and T.A. Wesche, 1998. Snorkeling as an Alternative to
Depletion Electrofishing for Estimating Abundance and Length-class Frequencies of
Trout in Small Streams. North American Journal of Fisheries Management 18:947-953.
Mulvihill, C.I., A.G. Ernst and B.P. Baldigo, 2006. Regionalized Equations for Bankfull
Discharge and Channel Characteristics of Streams in New York State: Hydrologic
Region 6 in the Southern Tier of New York. US Geological Survey Water-Resources
Investigation Report 2004-5100, US Geological Survey, Reston, Virginia.
Murphy, M.L., C.P. Hawkins, and N.H. Anderson, 1981. Effects of Canopy Modification
and Accumulated Sediment on Stream Communities. Transactions of the American
Fisheries Society 110(4):469-478.
Naiman, R.J., D.G. Lonzarich, TJ. Beechie, and S.C. Ralph, 1992. General Principles of
Classification and the Assessment of Conservation Potential in Rivers. In: River Con-
servation and Management, P. Boon, P. Calow, and G. Petts, (Editors). John Wiley and
Sons, Chichester, United Kingdom, pp. 93-123.
Naiman, RJ. and H. Decamps, 1997 The Ecology of Interfaces — Riparian Zones. Annual
Review of Ecology and Systematics 28:621-658.
A Function-Based Framework » May 2012 266
-------
References
Nanson, G.C. and J.C. Croke, 1992. A Genetic Classification of Floodplains. Geomorphology
4:459- 486.
National Park Service (NFS) and George Mason University, 2010. Ecological Assessment
Methods Database. National Biological Information Infrastructure (NBII), Center for
Biological Informatics of the US Geological Survey, assessmentmethods.nbii.gov
New Mexico Environment Department/Surface of Water Quality Bureau (NMED/
SWQB), 2009. Hydrology Protocol for the Determination of Ephemeral, Intermittent,
and Perennial Waters — DRAFT. ftp.nmenv.state.nm.us/www/swqb/MAS/Hydrology/
NMHydroProtocol-PublicCommentDraft08-2009.pdf
Newbold, J.D., 1992. Cycles and Spirals of Nutrients. In: The Rivers Handbook. I. Hydro-
logical and Ecological Principles, P. Calow and G.E. Petts (Editors). Blackwell Scientific
Publishers, Oxford, United Kingdom, pp. 379-408.
Newbold, J.D., P.S. Mulholland, J.W Elwood, and R.J. O'Neill, 1982. Organic Carbon
Spiraling in Stream Ecosystems. Oikos 38:266-272.
Newbold, J.D., J.W. Elwood, R.V. O'Neill, and W Van Winkle, 1981. Measuring Nutrient
Spiraling in Streams. Canadian Journal of Fisheries and Aquatic Sciences 38:860-863.
Nixon, M., 1959. A Study of Bankfull Discharges of Rivers in England and Wales. Institu-
tion of Civil Engineers Proceedings, 12(2):157-174.
North Carolina Department of Environment and Natural Resources (NCDENR), Division
of Water Quality (DWQ), 2005. Methodology for Identification of Intermittent and
Perennial Streams and Their Origins, V.3.1. Raleigh, North Carolina, portal.ncdenr.
Org/c/document_library/get_file?uuid=6b6a0403-d445-43de-8e29-83bc549fdf88&groupld=38364
NCDENR, DWQ, 2006. Standard Operating Procedures for Macroinvertebrates.
NCDENR Biological Assessment Unit, Raleigh, North Carolina.
NCDENR, DWQ, 2010. Methodology for Identification of Intermittent and Perennial
Streams and Their Origins, V.4.0. Raleigh, North Carolina, portal.ncdenr.org/c/docu-
ment_library/get_file?uuid=59f76e1a-9c9f-43e3-a764-a2703239fe36&groupld=38364
O'Hare M.T., A. Baattrup-Pedersen, R. Nijboer, K. Szoszkiewicz, and T Ferreira, 2006.
Macrophyte Communities of European Streams with Altered Physical Habitat. Hydro-
biologia 566:197-210.
A Function-Based Framework » May 2012 267
-------
References
Opperman, JJ. and A.M. Merenlender, 2004. The Effectiveness of Riparian Restoration
for Improving Instream Fish Habitat in Four Hardwood-dominated California Streams.
North American Journal of Fisheries Management 24:822-834.
Orzetti, L.L., R.C. Jones, and R.F. Murphy, 2010. Stream Condition in Piedmont Streams
with Restored Riparian Buffers in the Chesapeake Bay Watershed. Journal of the
American Water Resources Association 46(3):474-485.
Passauer, B., P. Meilinger, A. Melzer, and S. Schneider, 2002. Does the Structural Quality
of Running Waters Affect the Occurrence of Macrophytes? Acta Hydrochimica et
Hydrobiologica 30:197-206.
Payn, R.A., J.R. Webster, P.J. Mulholland, H.M. Valett, and W.K. Dodds, 2005. Estimation
of Stream Nutrient Uptake from Nutrient Addition Experiments. Limnology and
Oceanography: Methods 3:174-182.
Peckarsky, B.L., 1990. Freshwater Macroinvertebrates of Northeastern North America.
Comstock Publishing, Sacramento, California. ISBN-13: 978-0801496882.
Penn State-Westmoreland Conservation District, 2003. Macroinvertebrate Identification
Workshop, Virginia Save-Our-Streams Protocol. Stroud Water Research Center, Dono-
hoe Center, Greensburg, Virginia.
Peterson B.J. and B. Fry, 1987. Stable Isotopes in Ecosystem Studies. Annual Review of
Ecology and Systematics 18:293-320.
Phillips, J.D., 1989. Hillslope and Channel Sediment Delivery and Impacts of Soil Erosion
on Water Resources. Sediment and the Environment, Proceedings of the Baltimore
Symposium. International Association of Hydrological Sciences Publication 184.
Pitlick, ]., Y.T. Cui, and P.R. Wilcock, 2009. Manual for Computing Bed Load Transport
Using BAGS (Bedload Assessment for Gravel-bed Streams) Software, General Technical
Report RMRS-GTR-223. US Department of Agriculture, Forest Service, Rocky Moun-
tain Research Station, Fort Collins, Colorado, www.fs.fed.us/rm/pubs/rmrs_gtr223.pdf
Pizzuto, J.E., 1987 Sediment Diffusion During Overbank Flows. Sedimentology 34:301-317
Prichard, D., J. Anderson, C. Correll, J. Fogg, K. Gebhardt, R. Krapf, S. Leonard, B. Mitch-
ell, and J. Staats, 1998. Riparian Area Management: A User Guide to Assessing Proper
Functioning Condition and the Supporting Science for Lotic Areas, Technical Report
1737-15. US Department of the Interior, Bureau of Land Management, US Department
of Agriculture Forest Service, and Natural Resources Conservation Service, ftp.blm.gov/
pub/nstc/techrefs/Final%20TR %201737- 15.pdf
A Function-Based Framework » May 2012 268
-------
References
Pruitt, B.A., SJ. Miller, C.H. Theiling, and J.C. Fischenich, 2012. The Use of Reference
Ecosystems as a Basis for Assessing Restoration Benefits, EBA Technical Notes Collec-
tion, ERDC TN-EMRRP-EBA-12-##. US Army Engineer Research and Development
Center, Vicksburg, Mississippi, cw-environmentusace.army.mil/eba
Quinn, J.M., N.R. Phillips, and S.M. Parkyn, 2007. Factors Influencing Retention of
Coarse Particulate Organic Matter in Streams. Earth Surface Processes and Landforms
32:1186-1203.
Richardson, J.S., 1993. Limits to Productivity in Streams: Evidence from Studies of Mac-
roinvertebrates. In: Production of Juvenile Atlantic salmon, Salmo salar, in Natural
Waters, RJ. Gibson and R.E. Cutting (Editors). Canadian Special Publication of Fisher-
ies and Aquatic Sciences 118:9-15.
Richardson, J.S., R.E. Bilby, and C.A. Bondar, 2005. Organic Matter Dynamics in Small
Streams of the Pacific Northwest. Journal of the American Water Resources Associa-
tion 41(4):921-934.
Rohde, EC., R.G. Arndt, D.G. Lindquist, and J.F. Parnell, 1994. Fishes of the Carolinas,
Virginia, Maryland, and Delaware. University of North Carolina Press, Chapel Hill,
North Carolina.
Rosgen, D.L., 1994. A Classification of Natural Rivers. Catena 22:169-199.
Rosgen, D.L., 1996. Applied River Morphology. Wildland Hydrology Books, Pagosa
Springs, Colorado.
Rosgen, D.L., 1997. A Geomorphological Approach to Restoration of Incised Rivers. In:
Proceedings of the Conference on Management of Landscapes Disturbed by Channel
Incision, S.S.Y. Wang, EJ. Langendoen, and F.D. Shields (Editors). University of Missis-
sippi, Oxford, Mississippi.
Rosgen, D.L., 1998. The Reference Reach — A Blueprint for Natural Channel Design.
Proceedings from Wetlands and Restoration Conference, American Society of Civil
Engineers, Denver, Colorado.
Rosgen, D.L., 2001. A Practical Method of Computing Streambank Erosion Rate. Proceed-
ings of the Seventh Federal Interagency Sedimentation Conference, Reno, NV. II: 9-15.
Rosgen, D.L. 2001(a). A Stream Channel Stability Assessment Methodology. Proceedings
of the Federal Interagency Sediment Conference, Reno, Nevada, 11:18-26.
A Function-Based Framework » May 2012 269
-------
References
Rosgen, D.L., 2009. A Watershed Assessment for River Stability and Sediment Supply
(WARSSS). Wildland Hydrology Books, Fort Collins, Colorado, www.epa.gov/warsss
Rosgen, D.L., 2010. The Toe Wood Structure. Conference Workshop, Stream Restoration
in the Southeast, Connecting Communities with Ecosystems. North Carolina State
University, Raleigh, North Carolina.
Rosgen, D.L. and L. Silvey, 1998. Field Guide for Stream Classification. Wildland Hydrol-
ogy Books, Pagosa Springs, Colorado.
Roth, N.E., J.D. Allan, and D.L. Erickson, 1996. Landscape Influences on Stream Biotic
Integrity Assessed at Multiple Spatial Scales. Landscape Ecology 11:141-156.
Scharffenberg, W.A. and M.J. Fleming, 2010. Hydrologic Modeling System HEC-HMS
Version 3.5 User's Manual. US Army Corps of Engineers Hydrologic Engineering
Center, Davis, California, http://www.hec.usace.army.mil/software/hec-hms/docu-
mentation.html
Schaumburg, ]., C. Schranz, J. Foerster, A. Gutowski, G. Hofmann, P. Meilinger, S.
Schneider, and U. Schmedtje, 2004. Ecological Classification of Macrophytes and
Phytobenthos for Rivers in Germany According to the Water Framework Directive.
Limnologica 34:283-301.
Schneider, S., T Krumpholz, and A. Melzer, 2000. Tropha" eindikation in Fliessgewa"
ssern mit Hilfe des TIM (Tropha" e-Index Macrophyten) — Erprobung eines neu
entwickelten Index im Inniger Bach. Acta Hydrochimica et Hydrobiologica 28:241-249.
Schoof, R., 1980. Environmental Impact of Channel Modification. Water Resources
Bulletin 16(4): 697-701.
Schoonover, J.E. and K.W.J. Williard, 2005. Ground Water Nitrate Reduction in Giant
Cane and Forest Riparian Buffer Zones. Journal of the American Water Resources
Association 39(2):347-354.
Schumm, S.A., 1977. The Fluvial System. Wiley, New York.
Sculthorpe, C.D., 1967. The Biology of Aquatic Vascular Plants. Edward Arnold, London,
United Kingdom.
Shields, Jr., F.D., R.E. Lizotte, Jr., S.S. Knight, C.M. Cooper, and D. Wilcox, 2010. The
Stream Channel Incision Syndrome and Water Quality. Ecological Engineering 36:78-90.
A Function-Based Framework » May 2012 270
-------
References
Sih A. and D.E.Wooster, 1994. Prey Behavior, Prey Dispersal, and Predator Impacts on
Stream Prey. Ecology 75(5):1199-1207.
Simpson, E.H. 1949. Measurement of Diversity. Nature, 163: 688.
Simon, A., 1989. A Model of Channel Response in Disturbed Alluvial Channels. Earth
Surface Processes andLandforms 14:11-26.
Simon, A. and E. Langendoen, 2006. A Deterministic Bank-Stability and Toe Erosion
Model for Stream Restoration. Proceedings of the Environmental and Water Resources
Council 2006 Meeting, Omaha, Nebraska, R. Graham (Editor). Environmental and Water
Resources Institute, American Society of Civil Engineers, Reston, Virginia, www.ars.
usda.gov/Research/docs.htm?docid=5044
Smith, D.G., 2001. Pennak's Freshwater Invertebrates of the United States, Fourth Edition.
John Wiley & Sons, New York, New York. ISBNO-471-35837-1.
Smith, J.W.N., 2005. Groundwater—Surface Water Interactions in the Hyporheic Zone.
Environment Agency, Science Report SC030155/SR1, Bristol, United Kingdom, publica-
tions. environment-agency.gov. uk/pdf/SCH00605BJCQ-e-e.pdf
Somerville, D.E., 2010. Stream Assessment and Mitigation Protocols: A Review of Com-
monalities and Differences. Contract No. GS-OOF-0032M, US Environmental Protec-
tion Agency, Washington, D.C.
Somerville, D.E. and B.A. Pruitt, 2004. Physical Stream Assessment: A Review of Selected
Protocols for Use in the Clean Water Act Section 404 Program. US Environmental
Protection Agency, Washington, D.C.
Southerland, M.T. and J.B. Stribling, 1995. Status of Biological Criteria Development and
Implementation. In: Biological Assessment and Criteria: Tools for Water Resource
Planning and Decision Making, WS. Davis and T.P. Simon (Editors). Lewis Publishers,
Boca Raton, Florida, pp. 81-96.
Stanford, J.A. and J.V. Ward, 1988. The Hyporheic Habitat of River Ecosystems. Nature
335:64-66.
Stevenson, R.J., 1996. An Introduction to Algal Ecology in Freshwater Benthic Habitats.
In: Algal Ecology: Freshwater Benthic Ecosystems, RJ. Stevenson, M.L. Bothwell, and
R.L. Lowe (Editors). Academic Press, San Diego, California, pp. 3-30.
A Function-Based Framework » May 2012 271
-------
References
Stevenson, R.J. and L.L. Bahls, 1999. Chapter 6: Periphyton Protocols. In: Rapid Bioassessment
Protocols for Use in Streams and Wadeable Rivers: Periphyton, Benthic Macroinverte-
brates and Fish, Second Edition, M.T. Barbour, J. Gerritsen, B.D. Snyder, and J.B. Stribling
(Editors). EPA 841-B-99-002, US Environmental Protection Agency, Washington, D.C.
Stevenson, RJ. and Y. Pan. 1999. Assessing Ecological Conditions in Rivers and Streams
with Diatoms. In: The Diatoms: Applications to the Environmental and Earth Sci-
ences, E. F. Stoermer and J. P. Smol (Editors). Cambridge University Press, Cambridge,
United Kingdom, pp. 11-40.
Stevenson, R. J. and J.P. Smol, 2003. Use of Algae in Environmental Assessments. In:
Freshwater Algae in North America: Classification and Ecology, J.D. Wehr and R.G.
Sheath (Editors). Academic Press, San Diego, California, pp. 775-804.
Stoddard, J.L., D.P. Larsen, C.P. Hawkins, R.K. Johnson, and R.H. Morris, 2006. Setting
Expectations for the Ecological Condition of Streams: The Concept of Reference
Condition. Ecological Applications 16(4): 1267-1276.
Stream Solute Workshop, 1990. Concepts and Methods for Accessing Solute Dynamics in
Stream Ecosystems. Journal of the North American Benthological Society 9:95-119.
Stromberg, J.C., V.B. Beauchamp, M.D. Dixon, SJ. Lite, and C. Paradzick, 2007. Impor-
tance of Low-flow and High-flow Characteristics to Restoration of Riparian Vegetation
along Rivers in Arid South-western United States. Freshwater Biology 52:651-679.
Stumm, W and JJ. Morgan, 1996. Aquatic Chemistry: Chemical Equilibria and Rates in
Natural Waters, Third Edition. John Wiley & Sons, Inc., New York, New York.
Sweeney, B.W., 1993. Streamside Forests and the Physical, Chemical, and Trophic Charac-
teristics of Piedmont Streams in Eastern North America. Water Science and Technol-
ogy 26:2653-2673.
Sweeney, B.W and J.G. Blaine, 2007. Resurrecting the In-Stream Side of Riparian Forests.
Journal of Contemporary Water Research and Education 136:17-27
Sweeney, B.W, T.L. Bott, J.K. Jackson, L.A. Kaplan, J.D. Newbold, L.J. Standley, WC.
Hession and RJ. Horwitz, 2004. Riparian Deforestation, Stream Narrowing, and Loss
of Stream Ecosystem Services. Proceedings of the National Academy of Sciences
101(39):14132-14137.
Sweet, WV. and J.W Geratz, 2003. Bankfull Hydraulic Geometry Relationships and
Recurrence Intervals for the North Carolina's Coastal Plain. Journal of the American
Water Resources Association 39(4): 861-871.
A Function-Based Framework » May 2012 272
-------
References
Taylor, P.D., L. Fahrig, K. Henein, and G. Merriam, 1993. Connectivity is a Vital Element
of Landscape Structure. Oikos 68(3):571-572.
Thomas, W.A., R.R. Copeland, and D.N. McComas, 2002. SAM Hydraulic Design Package for
Channels. US Army Engineer Research and Development Center, Coastal and Hydrau-
lics Laboratory, Vicksburg, Mississippi. www.ayresassociates.com/Web_SAMwin/docs.htm
Thorp, J.H. and A.P. Covich, 2009. Ecology and Classification of North American Fresh-
water Invertebrates, Third Edition. Academic Press, London, United Kingdom. ISBN-
13: 978-0123748553.
Thompson, P.D. and FJ. Rahel, 1996. Evaluation of Depletion-Removal Electrofishing of
Brook Trout in Small Rocky Mountain Streams. North American Journal of Fisheries
Management 16:332-339.
Thurman, E.M., 1985. Organic Geochemistry of Natural Waters. Martinus Nijhoff,
Dordrecht, The Netherlands.
Thurow, R.F. and DJ. Schill, 1996. Comparison of Day Snorkeling, Night Snorkeling, and
Electrofishing to Estimate Bull Trout Abundance and Size Structure in a Second-order
Idaho Stream. North American Journal of Fisheries Management 16:314-323.
Tomer, M.D., T.B. Moorman, J.L. Kovar, D.E. James, and M.R. Burkart, 2007. Spatial
Patterns of Sediment and Phosphorus in a Riparian Buffer in Western Iowa. Soil and
Water Conservation Journal 62(5):329-338.
Topping, B.J.D., T Nadeau, and M.R. Turaski, 2009. Oregon Streamflow Duration Assess-
ment Method Interim Version. Public Notice release date, 6 March 2009. www.oregon-
statelands.us/DSL/PERMITS/docs/osdam_march_2009.pdf?ga=t
Tremp, H. and A. Kohler, 1995. The Usefulness of Macrophyte Monitoring-Systems,
Exemplified on Eutrophication and Acidification of Running Waters. Acta Botanica
Gallica 142:541-550.
Tweedy, K., 2010. Personal Communication about the Flowline Products Flow Measure-
ment Device. Michael Baker Engineering, Inc., Gary, NC.
US Army Corps of Engineers (USAGE), 2010. Operational Draft Regional Guidebook for
the Functional Assessment of High-gradient Ephemeral and Intermittent Headwater
Streams in Western West Virginia and Eastern Kentucky, ERDC/EL TR-10-11. US
Army Engineer Research and Development Center, Vicksburg, Mississippi.
A Function-Based Framework » May 2012 273
-------
References
USAGE Charleston District, 2010. Guidelines for Preparing a Compensatory Mitigation
Plan. www.sac.usace.army.mil/?action=mitigation.home
USAGE Galveston District, 2011. Interim Galveston District Stream Condition Assess-
ment Standard Operating Procedure for Compensatory Stream Mitigation, www.swg.
usace. army. mil/reg/documents/Stream_ SOP.pdf
USACE Norfolk District and Virginia Department of Environmental Quality (VDEQ),
2007.Unified Stream Methodology for use in Virginia, www.nao.usace.army.mil/techni-
cal%20services/Regulatory%20branch/USM/USM_Final_Draft.pdf
USACE Savannah District, 2004. Standard Operating Procedure for Compensatory
Mitigation. www.sas.usace.army.mil/regulatory/documents/SOP.04.pdf
USACE Wilmington District and North Carolina Department of Environment and Natu-
ral Resources (NCDENR), 2005. Information Regarding Stream Restoration in the
Outer Coastal Plain of North Carolina. www.saw.usace.army.mil/wetlands/Policies/
HWM12_1_05.pdf
USACE Wilmington District, US Environmental Protection Agency (USEPA), North
Carolina Wildlife Resource Commission (NCWRC), and NCDENR, 2003. Stream
Mitigation Guidelines. www.saw.usace.army.mil/WETLANDS/Mitigation/Documents/
Stream/STREAM%20MITIGATION%20GUIDELINE%20TEXT.pdf
US Department of Agriculture (USDA), National Resources Conservation Service (NRCS),
1998. Stream Visual Assessment Protocol. National Water and Climate Center Techni-
cal Note 99-1. www.nrcs.usda.gov/technical/ecs/aquatic/svapfnl.pdf
USDA, NRCS, 2007. Part 654 — Stream Restoration Design. In: NRCS National Engineer-
ing Handbook Part 654 — Stream Restoration Design, H.210.NEH.654. www.nrcs.usda.
gov/technical/ENG
USDA, NRCS, 2009a. The Computer Program for Project Formulation Hydrology Win-
TR-20. ver 1.11. http://www.wsi.nrcs.usda.gov/products/w2q/h&h/tools_models/WinTR20.html
USDA, NRCS. 2009b. Urban Hydrology for Small Watersheds WinTR-55. Technical
Release 210-VI-TR-55 Second edition, Version 1.00.09. Washington, D.C. www.wsi.nrcs.
usda.go v/pmducts/w2q/h & h/tools_models/wintr55. html.
US Environmental Protection Agency (USEPA). 1997a. Monitoring Guidance for Deter-
mining the Effectiveness of Nonpoint Source Controls. EPA/841-B-96-004, US Environ-
mental Protection Agency, Nonpoint Source Control Branch, Washington, D.C.
A Function-Based Framework » May 2012 274
-------
References
USEPA, 1997b. Volunteer Stream Monitoring: A Methods Manual. EPA 841-B-97-003, US
Environmental Protection Agency, Washington, D.C. www.epa.gov/volunteer/stream/
stream.pdf
USEPA 2000. Nutrient Criteria Technical Guidance Manual Rivers and Streams. EPA
822-B-00-002, US Environmental Protection Agency, Washington, D.C. www.epa.gov/
waterscience/criteria/nutrient/guidance/rivers/rivers-streams-full.pdf
USEPA, 2002. Standard Operating Procedure for Benthic Invertebrate Field Sampling
Procedure. LG406, 7:1-5, US Environmental Protection Agency, Washington, D.C.
www.epa.gov/glnpo/monitoring/sop/chapter_4/LG406.pdf
USEPA, 2003a. National Management Measures to Control Nonpoint Source Pollution
from Agriculture. EPA 841-B-03-004, US Environmental Protection Agency, Washing-
ton, D.C. water.epa.gov/polwaste/nps/agriculture/agmm_index.cfm
USEPA, 2003b. Elements of a State Water Monitoring and Assessment Program. EPA
841-B-03-003, US Environmental Protection Agency, Washington, D.C. www.epa.gov/
owow/monitoring/repguid.html
USEPA, 2007. The National Water Quality Standards Database (WQSDB), Release 9. US
Environmental Protection Agency, Washington, D.C. www.epa.gov/waterscience/
standards/wqslibrary
USEPA, 2008. Acid Rain. Available at www.epa.gov/acidrain
USEPA, 2009. National Water Quality Inventory: Report to Congress for the 2004 Report-
ing Cycle. US Environmental Protection Agency, Washington, D.C. water.epa.gov/
lawsregs/guidance/cwa/305b/upload/2009_01_22_305b_2004report_2004_305Breport.pdf
USEPA, 2011. United States Code of Federal Regulations Title 40 Part 131, Subpart B:
Establishment of Water Quality Standards, water.epa.gov/scitech/swguidance/waterqual-
ity/standards/Laws-and-Regulations.cfm
USEPA, 2012. EPA, 2012. National Summary of State Information: causes of impairment
in assessed rivers and streams. URL: iaspub.epa.gov/waters10/attains_index.controllast
updated 3/7/2012, accessed 3/7/2012.
US Geological Survey (USGS). 1981. Guidelines for Determining Flood Flow Frequency,
Bulletin 17b of the Hydrology Subcommittee. US Geological Survey, Reston, Virginia.
water.usgs.gov/osw/bulletin17b/bulletin_17B.html
A Function-Based Framework » May 2012 275
-------
References
USGS, 2010. National Field Manual for the Collection of Water-Quality Data: US Geologi-
cal Survey Techniques of Water-Resources Investigations, Book 9, Chapters. A1-A9. US
Geological Survey, Reston, Virginia. pubs.water.usgs.gov/twri9A.
Vannote, R.L., G.W Minshall, K.W. Cummins, J.R. Sedell, and C.E. Gushing, 1980. The
River Continuum Concept. Canadian Journal of Fisheries and Aquatic Sciences 37:130-137.
Vervier, P., J. Gibert, P. Marmonier and MJ. Dole-Oliver, 1992. A Perspective on the
Permeability of the Surface Freshwater-Groundwater Ecotone. Journal of the North
American Benthological Society 11:93-102.
Voshell, J.R., 2002. A Guide to Common Freshwater Invertebrates of North America. The
McDonald & Woodward Publishing Co., Blacksburg, Virginia.
Wagner, R.J., R.W Boulger, Jr., C.J Oblinger, and B.A. Smith, 2006. Guidelines and Stan-
dard Procedures for Continuous Water-Quality Monitors: Station Operation, Record
Computation and Data Reporting. Techniques and Methods 1D-3, US Geological
Survey, Reston, Virginia, pubs.water.usgs.gov/tm1d3
Wallace, J.B., J.J. Hutchens, Jr., and J.W. Grubaugh, 2006. Transport and Storage of FPOM.
In: Methods in Stream Ecology, Second Edition, R.F. Hauer and G.A. Lamberti (Edi-
tors). Elsevier, Oxford, United Kingdom, pp. 249-271.
Wallace J.B. and J.R. Webster, 1996. The Role of Macroinvertebrates in Stream Ecosystem
Function. Annual Review of Entomology 41:115-139.
Walling, D.E., 1984. Dissolved Loads and Their Measurement. In: Erosion and Sediment
Yield: Some Methods of Measurement and Modeling, R.F. Hadley and D.E. Walling
(Editors). Geo Books, Regency House, Norwich, United Kingdom, pp. 111-177
Warren, C.E., 1971. Biology and Water Pollution Control. W.B. Saunders, Philadelphia,
Pennsylvania.
Watson, I. and A.D. Burnett, 1993. Hydrology: An Environmental Approach. Buchanan
Books, Fort Lauderdale, Florida.
Webster, J.R. and E.F. Benfield, 1986. Vascular Plant Breakdown in Freshwater Ecosys-
tems. Annual Review of Ecological System 17: 567-594.
Webster, J.R., E.F. Benfield, T.P. Ehrman, M.A. Schaeffer, J.L. Tank, J.J. Hutchens, and D.J.
DAngelo, 1999. What Happens to Allochthonous Material that Falls into Sttreams? A
Synthesis of New and Published Information from Coweeta. Freshwater Biology 41:684-705.
A Function-Based Framework » May 2012 276
-------
References
Webster, J.R. and J.L. Meyer, 1997. Stream Organic Matter Budgets—A Synthesis. Journal
of the North American Benthological Society 16:141-161.
Webster, J.R. and H.M. Valett, 2006. Solute Dynamics. In: Methods in Stream Ecology,
Second Edition, R.F. Hauer and G.A. Lamberti (Editors). Elsevier, Oxford, United
Kingdom, pp. 169-185.
Weitzel, R.L., 1979. Methods and Measurements of Periphyton Communities: A Review.
American Society for Testing and Materials, Committee D-19 on Water.
Westlake, D.F., 1974. Macrophytes. In: A Manual on Methods for Measuring Primary
Production in Aquatic Environments, IBP Handbook 12, R.A. Vollenweider (Editor),
Blackwell Scientific Publications, Oxford, United Kingdom, pp 32-42.
Wetzel, R.G., 1983. Periphyton of Aquatic Ecosystems. BY. Junk Publishers, The Hague.
Wetzel, R.G., 2001. Limnology, Lake and River Ecosystems, Third Edition. Academic
Press, London, United Kingdom.
Wetzel, R.G. and G.E. Likens, 2000. Limnological Analyses, Third Edition. Springer-Ver-
lag, Inc., New York, New York.
Whipple, W., J. DiLouie, and J. Pytlar, 1981. Erosion Potential of Streams in Urbanizing
Areas. Water Resources Bulletin 17(1):36-45.
White, D.S. and S.P. Hendricks, 2000. Lotic Macrophytes and Surface-Subsurface Ex-
change Processes. In: Streams and Ground Waters, J.B. Jones and PJ. Mulholland
(Editors). Academic Press, San Diego, California, pp. 363-379.
Whittaker, J.G., 1987. Sediment Transport in Step-pool Streams. In: Sediment Transport
in Gravel-Bed Rivers, C.R. Thorne, J.C. Bathurst, and R.D. Hey (Editors). John Wiley,
New York, New York, pp. 545-579.
Wiegner, T.N. and S.P. Seitzinger, 2001. Photochemical and Microbial Degradation of
External Dissolved Organic Matter Inputs to Rivers. Aquatic Microbial Ecology 24:27-40.
Wilcock, P., J. Pitlick and Y Cui, 2009. Sediment Transport Primer: Estimating Bed-Mate-
rial Transport in Gravel-bed Rivers. General Technical Report RMRS-GTR-226, US
Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fort
Collins, Colorado, www.fs.fed.us/rm/pubs/rmrs_gtr226.pdf
A Function-Based Framework » May 2012 277
-------
References
Wiley, J.B., J.T. Atkinsjr., and D.A. Newell, 2002. Estimating the Magnitude of Annual
Peak Discharges with Recurrence Intervals between 1.1 and 3.0 Years for Rural, Un-
regulated Streams in West Virginia. US Geological Survey Water Resources Investiga-
tions Report 02-4164, US Geological Survey, Reston, Virginia.
Wilhm, J.L. and T.C. Dorris, 1968. Biological Parameters for Water Quality Criteria.
Bioscience 18:477-481.
Winter, T.C., W.H. Judson, O.L Franke, and WM. Alley, 1998. Groundwater and Surface
Water a Single Resource. Circular 1139, US Geological Survey, Denver, Colorado.
http://pubs.usgs.gov/circ/circll39
With, K.A., R.H. Gardner, and M.G. Turner, 1997. Landscape Connectivity and Popula-
tion Distributions in Heterogeneous Environments. Oikos 78:151-169.
Wohl, E.E., 2004. Disconnected Rivers, Linking Rivers to Landscapes. Yale University,
New Haven, Connecticutt. ISBN-0-300-I0332-8.
Wohl, E.E., 2000. Mountain Rivers. Water Resources Monographs 14, American Geophys-
ical Union, Washington, D.C.
Wohl, E.E. and D.M. Thompson, 2000. Velocity Characteristics Along a Small Step-Pool
Channel. Earth Surface Processes and Landforms, 25(4):353-367
Wohl, E.E., D.A. Cenderelli, K.A. Dwire, S.E. Ryan-Burkett, M.K. Young, and K.D.
Fausch, 2009. Large In-Stream Wood Studies: A Call for Common Metrics. Earth
Surface Processes and Landforms 35:618-625.
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. and J.P. Miller, 1960. Magnitude and Frequency of Forces in Geomorphic
Process. Journal of Geology 68:54-74.
Wootten, R.J., 1992. Fish Ecology, Tertiary Level Biology. Chapman & Hall, New York,
New York.
Wroblicky, G.J., M.E. Campana, H.M. Valett and D.C.N. Dahm, 1998. Seasonal Variation
in Surf ace-Subsurface Water Exchange and Lateral Hyporheic Area of Two Stream-
aquifer Systems. Water Resources Research 34:317-328.
A Function-Based Framework » May 2012 278
-------
References
Wynn, T., S. Mostaghimi, J.A. Burger, A.A. Harpold, M.B. Henderson, and L. Henry,
2004. Variation in Root Density along Stream Banks. Journal of Environmental Qual-
ity 33:2030-2039.
Zippin, C., 1956. An Evaluation of the Removal Method of Estimating Animal Popula-
tions. Biometrics 12:163-169.
WEB REFERENCES
Chapter 1
Training Resources
training.fws.gov
www.stream-mechanics.com
Technical Resources for Stream Mitigation
water.epa.gov/lawsregs/guidance/wetlands/wetlandsmitigationjndex.cfm
Chapter 2
EPA Stream and Wetland Mitigation Resources
water.epa.gov/lawsregs/guidance/wetlands/wetlandsmitigationjndex.cfm
Chapter 3
Guidelines for Preparing a Compensatory Mitigation Plan, Charleston District, USAGE
www. sac. usace. army. mil/?action=mitigation. home
Compensatory Stream Mitigation Standard Operating Procedures and Guidelines
(Draft), Mobile District, USACE www.sam.usace.army.mil/RD/reg/docs/2011 Draft Stream
SOP.pdf
Standard Operating Procedure for Compensatory Mitigation, Savannah District, USACE
http://www.sas.usace.army.mil/regulatory/documents/SOP.04.pdf
Stream Mitigation Guidelines, Wilmington District, USACE, www.saw.usace.army.mil/
WETLANDS/Mitigation/Documents/Stream/STREAM MITIGATION GUIDELINE TEXT.pdf
Unified Stream Methodology, Norfolk District USACE, www.nao.usace.army.mil/technical
services/Regulatory branch/USM/USMJ:inaLDraft.pdf
Stream Corridor Restoration: Principles, Processes and Practices
www.nrcs.usda. gov/technical/stream_restoration
A Function-Based Framework » May 2012 279
-------
References
Watershed Scale Restoration
http://water.epa.gov/type/watersheds/approach.cfm
Natural Resources Conservation Service National Engineering Handbook Part 654
Stream Restoration Design
www.nrcs.usda.gov/technical/ENG
Chapter 5
Natural Resources Conservation Service, National Engineering Handbook
directives, sc.egov.usda.go v/vie werFS. aspx ? id=3491
Somerville (additional assessment methodologies)
water.epa.gov/lawsregs/guidance/wetlands/upload/Stream-Protocols_2010.pdf
Stream Channel Reference Sites: An Illustrated Guide to Field Technique
www. stream, fs. fed. us/publications/PDFs/RM245E. PDF
The Reference Reach — A Blueprint for Natural Channel Design
www.wildlandhydrology.com/assets/The_Reference_Reach_ll.pdf
Proper Functioning Condition
ftp.blm.gov/pub/nstc/techrefs/Final TR 1737-9.pdf
Watershed Assessment of River Stability and Sediment Supply
water, epa.gov/scitech/datait/tools/warsss/index. cfm
Size Class Pebble Count Analyzer
www. stream, fs. fed. us/publications/software.html
Channel Evolution Models/Stream Type Succession Scenarios
www.nrcs.usda. gov/technical/stream_restoration/
Rosgen Stream Type Succession Scenarios
water, epa.gov/scitech/datait/tools/warsss/successn. cfm
Regional Curves
water. epa.gov/lawsregs/guidance/wetlands/upload/Appendix-A_ Regional_ Curves.pdf
EPA Rapid Bio-assessment Protocol (RBP)
water.epa.gov/scitech/monitoring/rsl/bioassessment/index.cfm
A Function-Based Framework » May 2012 280
-------
References
Index of Biotic Integrity (IB)
www.epa.gov/bioiweb1/html/ibLhistory.html
NRCS Stream Visual Assessment Protocol
www.nrcs.usda.gov/wps/portal/nrcs/detailfull/national/technical/alphabetical/water/restoration
/?&cid=stelprdbW43249
Monitoring Wilderness Stream Ecosystems
www. fs. fed. us/rm/pubs/rmrs_gtr70.pdf
EPA Statistical Primer
www.epa.gov/bioindicators/statprimer/statistical_testing.html
Chapter 6
Watershed Assessment of River Stability and Sediment Supply (WARSSS)
www. epa.gov/warsss
Methods for Identifying Bankfull
www. stream, fs. fed. us/publications/PDFs/RM245E. PDF
Methods for Identifying Bankfull in North Carolina Streams
www.bae.ncsu.edu/programs/extension/wqg/srp/rv-crs-3.pdf
Hydrologic Modeling System (HEC-HMS)
www.hec.usace.army.mil/software/hec-hms
Regional Regression Equations
water, usgs. go v/software/NFF
FEMA Regulated Floodplains Information
www.msc.fema.gov
USGS Bulletin 17b
water.usgs.gov/osw/bulletin17b/bulletin_17B.html
NC Department of Environment and Natural Resources, Division of Water Quality V. 3.1
portal. ncdenr.org/c/document_library/get_file?uuid=6b6a0403-d445-43de-8e29-
83bc549fdf88&groupld=38364
V.4.0: portal.ncdenr.org/c/document_library/get_file?uuid=59f76e1a-9c9f-43e3-a764-
a2703239fe36&groupld=38364
A Function-Based Framework » May 2012 281
-------
References
Oregon Streamflow Duration Assessment Method Interim Version
www.oregonstatelands.us/DSL/PER MITS/docs/osdam_march_2009.pdf?ga=t
Hydrology Protocol for the Determination of Ephemeral, Intermittent and Perennial
Waters (DRAFT 8/09)
ftp.nmenv.state.nm.us/www/swqb/MAS/Hydrology/NMHydroProtocol-PublicComment-
Draft08-2009.pdf
Chapter 7
FishXing Website
www. stream, fs. fe d. us/fis fixing/index, html
Chapter 8
SAMWin
chl. erdc. usace. army, mil/chl. aspx ?p=s&a=SOFTWA RE; 2
2-D Models with Hydraulic and Sediment Transport Modeling Capabilities
RiverFLO-2D: www.flo-2d.com/products
Mike 21: www.mikebydhi.com
RIVERMorph Software Program
www. rivermorph. com
BAGS Program
www. stream, fs. fed. us/publications/bags. html
Technical Resources for Mitigation
water.epa.gov/lawsregs/guidance/wetlands/wetlandsmitigation_index.cfm
Parameters and Methods of Measurement
stream, fs. fed. us/publications/documentsStream. html
Assessing Proper Functioning Condition for Lotic Areas
ftp.blm.gov/pub/nstc/techrefs/Final%20TR%201737-15.pdf
NRCS Stream Visual Assessment Protocol (SVAP)
www.nrcs.usda.gov/technical/ecs/aquatic/svapfnl.pdf
Watershed Assessment of River Stability and Sediment Supply (WARSSS) Prediction Level
Assessment (PLA) Index
water.epa.gov/scitech/datait/tools/warsss/pla_box07.cfm
A Function-Based Framework » May 2012 282
-------
References
US 301 Environmental Stewardship Study
Link: www.fws.gov/chesapeakebay/streampub.html
Sampling and Analyzing Surface and Subsurface Particles
www. stream, fs. fed. us/publications/documentsStream. html
Spreadsheet Tools and Instructions for Managing Pebble Count Data
www. stream, fs. fed. us/publications/software.html
Chapter 9
EPA Database of State Water Quality Standards
www.epa.gov/waterscience/standards/wqslibrary
EPA Water Quality Monitoring Information
www. epa.gov/storet
Chapter 10
Ecological Assessment Methods Database
assessmentmethods.nbii.gov
Landscape Connectivity
Circuitscape: www.circuitscape.org/Circuitscape/Welcome.html
Conefor Sensinode: www.conefor.org
Funconn: www.nrel.colostate.edu/projects/starmap/funconnjndex.htm
Pathmatrix: cmpg. unibe. ch/software/pathmatrix
Chapter 11
Conducting Watershed Assessments
water, epa.gov/type/watersheds
A Function-Based Framework » May 2012 283
-------
3.QG iniGf IK
A Function-Based Framework » May 2012 284
-------
Appendices
A. STREAM FUNCTIONS PYRAMID
A. Overview Graphic
B. Functions & Parameters Graphic
C. Parameter & Measurement Method Table
D. Performance Standard Table
B. APPLICATION SCENARIOS
PERMITTED IMPACT SCENARIOS (DEBITS)
1. Culvert installations
2. Channelization and Bank Hardening
3. Surface Mining of High-Gradient Streams
STREAM MITIGATION SCENARIOS (CREDITS)
1. Restoration of Incised Channels in Alluvial Valleys
2. Restoration of Stream Flow for Channels That Have Excessive Water Withdrawal
3. Salmonid Fish Passage and Habitat Restoration
4. Restoration of High-Gradient, Headwater Streams
A Function-Based Framework » May 2012
285
-------
a
5
DO
o>
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID
a. OVERVIEW GRAPHIC
<^>
<^
HYDRAULIC »
Transport of water in the channel, on the floodplain, and through sediments
(0
3
Q.
x'
C/)
r^-
CD
£U
3
~n
c
D
O
r^-
o'
D
CO
QJ
3
Transport of water from the watershed to the channel
00
01
-------
a
5
CO
0)
v>
(0
o.
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID
b. STREAM FUNCTIONS PYRAMID: FUNCTIONS & PARAMETERS
BIOLOGY » FUNCTION: Biodiversity and the life histories of aquatic
and riparian life » PARAMETERS: Microbial Communities, Macrophyte
Communities, Benthic Macroinvertebrate Communities, Fish Communities,
Landscape Connectivity
PHYSICOCHEMICAL » FUNCTION: Temperature and oxygen regulation; processing
of organic matter and nutrients » PARAMETERS: Water Quality, Nutrients, Organic Carbon
GEOMORPHOLOGY » FUNCTION: Transport of wood and sediment to create diverse bed forms and dynamic
equilibrium » PARAMETERS: Sediment Transport Competency, Sediment Transport Capacity, Large Woody Debris
Transport and Storage, Channel Evolution, Bank Migration/Lateral Stability, Riparian Vegetation, Bed Form Diversity,
Bed Material Characterization
HYDRAULIC » FUNCTION: Transport of water in the channel, on the floodplain, and through sediments » PARAMETERS: Floodplain
Connectivity, Flow Dynamics, Groundwater/Surface Water Exchange
Transport of water from the watershed to the channel Channel-Forming Discharge, Precipitation/Runoff
Relationship, Flood Frequency, Flow Duration
(0
3
a.
x'
CD
QJ
3
~n
c
D
O
r^-
o'
D
CO
-0
<
QJ
3
00
-J
-------
a
5
CO
0)
v>
(0
o.
0)
3
(B
o
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID
c. PARAMETER & MEASUREMENT METHOD TABLE
(Details about the categories for the measurement methods, including type, level of effort, level of complexity, and direct/
indirect assessment, are provided in Chapter 4. The parameters and measurement methods shown here are examples. Addi-
tional parameters and measurement methods can be added based on user needs. Refer to Chapter 4 for instructions on how
to add parameters and measurement methods.)
HYDROLOGY
PARAMETER
Channel-Forming
Discharge
Precipitation/
Runoff
Relationship
Flood Frequency
Flow Duration
MEASUREMENT
METHOD
1. Regional Curves
1. Rational Method
2.HEC-HMS
3. USGS Regional
Regression
Equations
1. Bulletin 17b
1. Flow Duration
Curve
2. Crest Gauge
3. Monitoring
Devices
4. Rapid Indicators
TYPE
1. Technique
l.Tool
2. Tool
3. Technique
1. Technique
1. Technique
2. Tool
3. Tool
4. Assessment
approach
LEVELOFEFFORT
1. Rapid to
Intensive,
dependent on
curve
1. Rapid
2. Moderate
3. Rapid
1. Moderate
1. Moderate to
Intensive,
dependent on
data source
2. Rapid
3. Intensive
4. Rapid
LEVELOFCOMPLEXITY
1. Simple to
Complex,
dependent on
curve
1. Moderate
2. Complex
3. Moderate
3. Complex
1. Moderate/
Complex
2. Simple
3. Moderate
4. Simple
ASSESSMENT OF
PARAMETER
1. Indirect
1. Indirect
2. Indirect
3. Indirect
1. Direct
1. Direct/
Indirect
2. Indirect
3. Direct
4. Indirect
(0
3
Q.
x'
C/)
r^-
CD
£U
3
~n
c
D
O
r^-
o'
D
CO
QJ
3
00
00
-------
a
5
DO
0)
(A
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
c. PARAMETER & MEASUREMENT METHOD TABLE
HYDRAULICS
PARAMETER
Floodplain
Connectivity
Flow Dynamics
Ground water/
SurfaceWater
Exchange
MEASUREMENT
METHOD
1. Bank Height
Ratio
2. Entrenchment
Ratio
3. Stage Versus
Discharge
1. Stream Velocity
2. Shear Stress
3. Stream Power
1. Piezometers
2. Tracers
3. Seepage Meters
TYPE
1. Technique
2. Technique
3. Technique
1. Metric
2. Metric
3. Metric
I.Tool
2. Tool
3. Tool
LEVELOFEFFORT
1. Rapid/Moderate
2. Rapid/Moderate
3. Intensive
1. Moderate/
Intensive
2. Moderate/
Intensive
3. Moderate/
Intensive
1. Intensive
2. Intensive
3. Intensive
LEVELOFCOMPLEXITY
1. Simple/Moderate
2. Simple/Moderate
3. Complex
1. Moderate/
Complex
2. Moderate/
Complex
3. Moderate/
Complex
1. Complex
2. Complex
3. Complex
ASSESSMENT OF
PARAMETER
1. Direct
2. Direct
3. Indirect
1. Direct
2. Direct
3. Direct
1. Direct
2. Direct
3. Direct
(0
3
Q.
x'
C/)
r^-
CD
£U
3
~n
c
D
O
r^-
o'
D
CO
-0
<
QJ
3
00
u>
-------
a
5
DO
0)
(A
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
c. PARAMETER & MEASUREMENT METHOD TABLE
GEOMORPHOLOGY
PARAMETER
Sediment
Transport
Competency
Sediment
Transport
Capacity
Large Woody
Debris Transport
and Storage
MEASUREMENT
METHOD
1. Shear Stress
Curve
2. Required Depth
and Slope
3. Spreadsheets
and Computer
Models
1. Computer
Models
2. FLOWSED and
POWERSED
3. BAGS
LWohl LWD
Assessment
2. Large Woody
Debris Index
TYPE
1. Technique
2. Technique/
Tool
3. Tool
l.Tool
2. Tool
3. Tool
1. Assessment
approach
2. Assessment
approach
LEVELOFEFFORT
1. Rapid to
Intensive,
dependent on
curve availability
2. Moderate
3. Moderate/
Intensive
1. Moderate/
Intensive
2. Intensive
3. Rapid/Moderate
1. Rapid/Moderate
2. Moderate
LEVELOFCOMPLEXITY
1. Simple to
Complex,
dependent on
curve availability
2. Moderate
3. Moderate/
Complex
1. Moderate/
Complex
2. Complex
3. Simple/Moderate
1. Simple/Moderate
2. Moderate
ASSESSMENT OF
PARAMETER
1. Indirect
2. Indirect
3. Indirect
1. Indirect
2. Indirect
3. Indirect
1. Direct for
storage and
Indirect for
transport
2. Direct for
storage and
Indirect for
transport
(0
3
Q.
x'
C/)
r^-
CD
£U
3
~n
c
D
O
r^-
o'
D
CO
-0
<
QJ
3
CO
o
-------
a
5
DO
0)
(A
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
c. PARAMETER & MEASUREMENT METHOD TABLE
GEOMORPHOLOGY
PARAMETER
Channel Evolution
Bank Migration/
MEASUREMENT
METHOD
1. Simon Channel
Evolution Model
2. Rosgen Stream
Type Succession
Scenarios
1. Meander Width
Lateral Stability Ratio
2.BEHI/NBS
3. Bank Pins
4. Bank Profiles
5. Cross-Sectional
Surveys
6. Bank Stability
and Toe Erosion
Model
TYPE
1. Technique
LEVELOFEFFORT
1. Rapid/Moderate
2. Technique 2. Moderate
1. Technique
2. Technique/
1. Rapid/Moderate
2. Moderate/
Tool Intensive
3. Technique 3. Intensive
4. Technique 4. Intensive
5. Technique 5. Intensive
6. Tool
6. Intensive
LEVELOFCOMPLEXITY ASSESSMENT OF
1. Simple/Moderate
2. Moderate
1. Simple
2. Moderate
3. Moderate
4. Moderate
5. Moderate
6. Complex
PARAMETER
1. Indirect
2. Indirect
1. Indirect
2. Indirect
3. Direct
4. Direct
5. Direct
6. Indirect
(0
3
Q.
x'
C/)
r^-
CD
£U
3
~n
c
D
O
r^-
o'
D
CO
-0
<
QJ
3
u>
-------
a
5
DO
0)
(A
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
c. PARAMETER & MEASUREMENT METHOD TABLE
to
GEOMORPHOLOGY
PARAMETER
Riparian
Vegetation
MEASUREMENT
METHOD
1. Buffer Width
2. Buffer Density
3. Buffer
Composition
4. Buffer Age
5. Buffer Growth
6. Canopy Density
7. Proper
Functioning
Condition (PFC)
8. NRCS Visual
Assessment
Protocol
9. Rapid
Bioassessment
Protocol
10. Watershed
Assessment of
River Stability
and Sediment
Supply
(WARSSS)
11. USFWS Stream
Assessment
Ranking Protocol
(SAR) "
TYPE
LEVELOFEFFORT
1. Technique 1. Rapid
2. Technique 2. Moderate/
Intensive
3. Technique 3. Moderate/
Intensive
4. Technique 4. Intensive
5. Technique 5. Intensive
6. Technique 6. Moderate/
Intensive
7. Assessment 7. Rapid
approach
8. Assessment 8. Rapid
approach
9. Assessment 9. Rapid
approach
10. Assessment 10. Intensive
approach
11. Assessment 11. Rapid
approach
LEVELOFCOMPLEXITY
1. Simple
2. Moderate
3. Moderate
4. Moderate
5. Moderate
6. Moderate
7. Simple
8. Simple
9. Simple
10. Complex
11. Simple
ASSESSMENT OF
PARAMETER
1. Indirect
2. Direct
3. Direct
4. Direct
5. Direct
6. Direct
7. Indirect
8. Indirect
9. Indirect
10. Indirect
11. Indirect
(0
3
Q.
x'
C/)
r^>
CD
£U
3
~n
c
D
O
r^>
o'
D
CO
QJ
3
-------
a
5
DO
0)
(A
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
c. PARAMETER & MEASUREMENT METHOD TABLE
GEOMORPHOLOGY
PARAMETER
Bed Form
Diversity
Bed Material
Characterization
MEASUREMENT
METHOD
1. Percent Riffle
and Pool
2. Facet Slope
3. Pool-to-Pool
Spacing
4. Depth Variability
1. Size Class Pebble
Count Analyzer
2. Riffle Stability
Index (RSI)
TYPE
1. Technique
2. Technique
3. Technique
4. Technique
l.Tool
2. Technique
LEVELOFEFFORT
1. Rapid/Moderate
2. Moderate
3. Rapid/Moderate
4. Moderate
1. Moderate/
Intensive
2. Moderate/
Intensive
LEVEL OF COMPLEXITY
1. Moderate
2. Moderate
3. Moderate
4. Moderate
1. Moderate
2. Moderate
ASSESSMENT OF
PARAMETER
1. Direct
2. Indirect
3. Indirect
4. Direct
1. Direct
2. Indirect
PHYSICOCHEMICAL
CO
CO
PARAMETER
Water Quality
Nutrients
MEASUREMENT
METHOD
1. Temperature
2. Dissolved
Oxygen
3. Conductivity
4. pH
5. Turbidity
1. Field test kits
using reagents
reactions
2. Laboratory
analysis
TYPE
1. Metric
2. Metric
3. Metric
4. Metric
5. Metric
1. Technique
2. Technique
LEVELOFEFFORT
1. Rapid/Intensive
2. Rapid/Intensive
3. Rapid/ Intensive
4. Rapid /Intensive
5. Rapid/Intensive
1. Rapid for
screening
2. Intensive
LEVELOFCOMPLEXITY
1. Simple/Moderate
2. Simple/Moderate
3. Simple/Moderate
4. Simple/Moderate
5. Simple/Moderate
1. Simple
2. Complex
ASSESSMENT OF
PARAMETER
1. Direct
2. Direct
3. Direct
4. Direct
5. Direct
1. Direct
2. Direct
(0
3
Q.
x'
C/)
r^-
CD
£U
3
~n
c
D
O
r^-
o'
D
CO
-0
<
QJ
3
-------
a
5
DO
o>
0)
3
(B
O
CD
to
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
c. PARAMETER & MEASUREMENT METHOD TABLE
BIOLOGY
PARAMETER
Organic Carbon
Microbial
Communities
Macrophyte
Communities
Benthic
Macroinvertebrate
Communities
Fish Communities
Landscape
Connectivity
MEASUREMENT
METHOD
1. Laboratory
analysis
1. Taxonomic
Methods
2. Non-Taxonomic
Methods
3. Biological
Indices
1. Taxonomic
Methods
2. Non-Taxonomic
Methods
3. Biological
Indices
1. Taxonomic
Methods
2. Non-Taxonomic
Methods
3. Biological
Indices
1. Taxonomic
Methods
2. Non-Taxonomic
Methods
3. Biological
Indices
1. Spatial Analysis
2. Species Tracking
3. Habitat Models
TYPE
1. Technique
1. Technique
2. Technique
3. Assessment
approach
1. Technique
2. Technique
3. Assessment
approach
1. Technique
2. Technique
3. Assessment
approach
1. Technique
2. Technique
3. Assessment
approach
1. Technique
2. Technique
3. Technique
LEVELOFEFFORT
1. Intensive
1. Intensive
2. Intensive
3. Moderate/
Intensive
1. Intensive
2. Intensive
3. Moderate/
Intensive
1. Intensive
2. Intensive
3. Moderate/
Intensive
1. Intensive
2. Intensive
3. Moderate/
Intensive
1. Intensive
2. Intensive
3. Intensive
LEVELOFCOMPLEXITY
1. Complex
1. Complex
2. Complex
3. Moderate/
Complex
1. Complex
2. Complex
3. Moderate/
Complex
1. Complex
2. Complex
3. Moderate/
Complex
1. Complex
2. Complex
3. Moderate/
Complex
1. Complex
2. Complex
3. Complex
ASSESSMENT OF
PARAMETER
1. Direct
1. Direct
2. Direct
3. Indirect
1. Direct
2. Direct
3. Indirect
1. Direct
2. Direct
3. Indirect
1. Direct
2. Direct
3. Indirect
1. Direct
2. Direct
3. Direct
(D
3
Q.
x'
C/)
r^-
CD
Q}
3
~n
c
D
O
r^-
o'
D
CO
-------
a
5
CO
0)
v>
(0
o.
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID
d. PERFORMANCE STANDARDS TABLE
Notes:
1. Since there are no Hydrology Performance Standards, there is not a Hydology Summary Table
2. Many of the performance standard values, especially the dimensionless ratios, should be considered as examples that can
be modified based on regional differences in reference conditions.
3. Great care should be taken when selecting measurement methods and performance standards. Refer to Chapters 6-10 and
the associated references before selecting measurement methods and performance standards.
CO
Ul
HYDRAULIC
PARAMETER
Floodplain
Connectivity
Flow Dynamics
MEASUREMENT
METHOD
Bank Height Ratio
(BHR)
Entrenchment Ratio
(ER)forCand E Stream
Types
Entrenchment Ratio
(ER)for B and Be
Stream Types
Dimensionless rating
curve
Bankfull Velocity for C
and E stream types
(ft/s)
Bankfull Velocity for Cc
(ft/s)
Bankfull Velocity for B
stream types (ft/s)
PERFORMANCE STANDARD
FUNCTIONING
1.0 to 1.2
>2.2
> 1.4
Project site Q/Qbkf
plots on the curve
3 to 6
<3
4 to 6
FUNCTIONING-
AT-RISK
1.3 to 1.5
2.0 to 2. 2
1.2 to 1.4
Project site Q/Qbkf
plots above the
curve
6 to 7
3 to 4
6 to 7
NOT
FUNCTIONING
> 1.5
<2.0
< 1.2
Project site Q/Qbkf
of 2.0 plots above
1.6ford/dbkf
>7
>5
>7
SOURCE
Rosgen, 2001
(proceedings) and
1994 (book)
Dunne and
Leopold 1978
(book)
Dunne and
Leopold 1978
(book)
(0
3
Q.
x'
C/)
r^-
CD
£U
3
~n
c
D
O
r^-
o'
D
CO
-0
<
QJ
3
-------
a
5
DO
o>
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
GEOMORPHOLOGY
PARAMETER
MEASUREMENT
METHOD
PERFORMANCE STANDARD
FUNCTIONING
FUNCTIONING-
AT-RISK
NOT
FUNCTIONING
SOURCE
Large Woody
Debris
CO
at
Large Woody Debris
Index (LWDI)
LWDI of project
reach equals LWDI
LWDI of project
reach does not
LWDI of project
reach does not
Davis etal., 2001
(USFS Technical
Channel
Evolution
of reference reach.
equal LWDI of
reference reach,
but is trending in
that direction.
equal LWDI of
reference reach
and is not trending
in that direction.
Report)
Rosgen's Stream Type Succession Scenarios
1.E-»C-»Gc-»F-»C-»E
2.C-D-C
S.C-D-Gc-F-C
4.C-G-F-BC
B.E-Gc-F-C-E
6. B-G-Fb-B
7.Eb-G-B
8. C-»G-»F-»D-»C
9. C-»G-»F-»C
in F -> A ->f^ •* F i p ->F
11.C-F-C-F-C
„ _ _ P _ _ _
\
CD
Q}
3
~n
c
D
O
r^>
o'
D
CO
-------
a
5
DO
o>
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
to
-j
GEOMORPHOLOGY
PARAMETER
Channel
Evolution
Bank Migration/
Lateral Stability
MEASUREMENT
METHOD
4. Degradation and
widening
5. Aggradation and
widening
6. Quasi-equilibrium
PERFORMANCE STANDARD
FUNCTIONING
•/
FUNCTIONING-
AT-RISK
3.5 (based on
reference reach
surveys)
Very low to
Moderate NBS
Very low to Low
NBS
N/A
N/A
Erosion rate is
similarto
reference reach
values, generally
< 0.1 ft/yr
3.0 to 3. 5 as long
as sinuosity is
> 1.2
Moderate to Very
High NBS
Low to High NBS
Low to Moderate
NBS
Low NBS
0.1 to 0.5 ft/yr
0.5 ft/yr
Rosgen, 2001
(proceedings)
and 2006 (book)
(0
3
Q.
x'
C/)
r^>
CD
£U
3
~n
c
D
O
r^>
o'
D
CO
QJ
3
-------
a
5
DO
0)
(A
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
CO
00
GEOMORPHOLOGY
PARAMETER
Bank Migration/
Lateral Stability
Riparian
Vegetation
MEASUREMENT
METHOD
Lateral Erosion Rate for
C4 streams (Cross
Sections)
Bank Stability and Toe
Erosion Model
Average Buffer Width
(Ft) C and E Stream
Types
Buffer Width (Ft) from
Meander Belt Width for
C and E Stream Types
Buffer Density
(Stems/ac)
Buffer Age
Buffer Composition
Buffer Growth
Canopy Density
Proper Functioning
Condition (PFC)
PERFORMANCE STANDARD
FUNCTIONING
w/Dproj = 1.0 to
w/Dref *•*
Fs> 1.3
> 150
Meander belt
width at least 3.5
times the bankfull
width plus > 15
feet from outside
of meander bend
Parameter is
similar to
reference reach
condition, with no
additional
maintenance
required.
Proper
Functioning
Condition
FUNCTIONING-
AT-RISK
w/Dproj = 1.2 to
w/Dref '-4
1.0 1.3
30 to 150
Meander belt
width at least 3.5
times the bankfull
width plus 10 to 15
feet from outside
of meander bend
Parameter
deviates from
reference reach
condition, limiting
function, but the
potential exists for
full functionality
overtime or with
moderate
additional
maintenance.
Functional At-Risk
NOT
FUNCTIONING
w/Dproj = > 1.4
w/Dref
Fs< 1.0
<30
Meander belt
width < 3.5 times
the bankfull width
and/or < 10 feet
from outside of
meander bend
Significantly less
functional than
reference
condition; little or
no potential to
improve without
significant
restoration effort.
Nonfunctional
SOURCE
Simon and
Langendoen 2006
(proceedings)
Meyer etal., 2005
(journal)
Proposed as an
option in this
document
Prichard et al.,
1998 (USFS
Technical Report)
(0
3
Q.
x'
C/)
r^>
CD
£U
3
~n
c
D
O
r^>
o'
D
CO
QJ
3
-------
a
5
CO
0)
v>
(0
o.
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
GEOMORPHOLOGY
PARAMETER MEASUREMENT
METHOD
PERFORMANCE STANDARD
FUNCTIONING
FUNCTIONING-
AT-RISK
NOT
FUNCTIONING
SOURCE
NRCS Rapid Visual Natural vegetation Natural vegetation Natural vegetation NRCS Technical
Assessment Protocol extends at least extends at least less than one-third Report
Riparian The EPA Rapid
Vegetation Bioassessment
Protocol (RBP)
one to two active one-half to one- active channel
channel widths on third active widths on each
each side, or if channel widths on side, or lack of
less than one
each side, or regeneration, or
width, covers filtering function 1 filtering function
entire floodplain. moderately severly
(8-10)
compromised. (3-5)
compromised. (1)
Width of riparian Width of riparian Width of riparian Barbour et al.,
zone > 18 meters; zone 12-18 meters; zone < 6 meters; 1999 (EPA
humans have not human activities little or no riparian Technical Report)
impacted zone. have minimally vegetation due to
(Optimal, 9-10) impacted zone. human activity.
(Sub-Optimal, 6-8) (Poor, 0-2)
Width of riparian
zone 6-12 meters;
human activities
have impacted
zone a great deal.
(Marginal, 3-5)
(0
3
Q.
x'
C/)
r^>
CD
£U
3
~n
c
D
O
r^>
o'
D
CO
QJ
3
CO
u>
-------
a
5
CO
0)
v>
(0
o.
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
GEOMORPHOLOGY
PARAMETER
Riparian
Vegetation
MEASUREMENT
METHOD
PERFORMANCE STANDARD
FUNCTIONING
FUNCTIONING-
AT-RISK
USFWS Stream All three zones of Only Zone 2 of
Assessment Ranking vegetation exist; | vegetation is well
(SAR)
runoff is primarly represented;
sheet flow; runoff is equally
hillslopes < 10%; sheet and
hillslopes > 200 ft concentrated flow
from stream;
ponding or
wetland areas and
litter or debris
jams are well
represented.
(moderate gully
and rill erosion);
hillslopes 20-40%;
hillslopes 50-100 ft
from stream;
ponding or
wetland areas and
litter or debris
jams are
minimally
represented.
NOT
FUNCTIONING
SOURCE
No zones of Allen et al., 1999
vegetation well
represented;
runoff is primarily
concentrated flow
(extensive gully
and rill erosion);
hillslopes > 40%;
hillslopes < 50ft
from stream;
ponding or
wetland areas and
litter or debris
jams are not well
represented or
completely
absent.
(0
3
Q.
x'
C/)
r^>
CD
£U
3
~n
c
D
O
r^>
o'
D
CO
QJ
3
CO
o
o
-------
a
5
DO
0)
(A
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
CO
o
GEOMORPHOLOGY
PARAMETER
Bed Form
Diversity
MEASUREMENT
METHOD
PERFORMANCE STANDARD
FUNCTIONING
FUNCTIONING-
AT-RISK
NOT
FUNCTIONING
SOURCE
Perennial Streams in Alluvial Valleys (C, E)
Percent Riffle
Pool-to-Pool Spacing
Ratio (Watersheds < 10
mi2)
Pool-to-Pool Spacing
Ratio (Watersheds > 10
mi2)
Depth Variability -
Gravel Bed Streams
(Pool Max Depth Ratio)
Depth Variability -
Sand Bed Streams
(Pool Max Depth Ratio)
60 to 70
4 to 5
5 to 7
> 1.5
> 1.2
70 to 80
40 to 60
3 to 4 and 5 to 7
3. 5 to 5 and 7 to 8
1.2 to 1.5
1.1 to 1.2
>80
<40
<3.0 and >7
<3.5 and > 8
<1.2
< 1.1
Professional
Judgement
Leopold 1994,
Gregory et al.,
1994 journal),
Whittake 1987
(book), Chin 1989
(journal), and
Grant 1990
(journal)
Leopold 1994,
Gregory et al.,
1994 journal),
Whittake 1987
(book), Chin 1989
(journal), and
Grant 1990
(journal)
Rosgen 2006
(book)
(0
3
Q.
x'
C/)
r^>
CD
£U
3
~n
c
D
O
r^>
o'
D
CO
QJ
3
-------
a
5
DO
0)
(A
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
GEOMORPHOLOGY
PARAMETER
Bed Material
Characterization
Bed Form
Diversity
MEASUREMENT
METHOD
Bed material
composition
PERFORMANCE STANDARD
FUNCTIONING
Project Reach is
not statistically
different than
reference reach.
FUNCTIONING-
AT-RISK
N/A
NOT
FUNCTIONING
Project Reach is
statistically
different (finer)
than reference
reach.
SOURCE
Bevenger and
King, 2005 (USFS
Technical Report)
Moderate Gradient Perennial Streams in Colluvial Valleys
Pool-to-Pool Spacing
Ratio (Slope between 3
and 5%)
Depth Variability (Pool
Max Depth Ratio)
2 to 4
>1.5
4 to 6
1.2 to 1.5
>6
< 1.2
Leopold 1994,
Gregory et al.,
1994 journal),
Whittake 1987
(book), Chin 1989
(journal), and
Grant 1990
(journal)
Leopold 1994,
Gregory et al.,
1994 journal),
Whittake 1987
(book), Chin 1989
(journal), and
Grant 1990
(journal)
(0
3
Q.
x'
C/)
r^-
CD
£U
3
~n
c
D
O
r^-
o'
D
CO
QJ
3
CO
o
-------
a
DO
0)
(A
(D
Q.
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
PHYSICOCHEMICAL
PARAMETER
Water Quality
MEASUREMENT
METHOD
DO
Temperature
Turbidity
PH
Conductivity
Turbidity
PERFORMANCE STANDARD
FUNCTIONING
Meets water
quality standards
for designated use
Representative of
reference reach
and meets species
requirements
Representative of
values measured
in reference reach
FUNCTIONING-
AT-RISK
Meets water
quality standards
for designated use
Is not
representative of
reference reach
and does not
support species
requirements
Does not have
representative
reference reach
values or
Does not support
designated use or
species
requirements
NOT
FUNCTIONING
Does not meet
water quality
standards
Is not
representative of
the reference
reach
Does not support
species
requirements
Statistically
different than
reference reach
and does not
support aquatic
life
SOURCE
Performance
standards have not
been developed for
these parameters
and are therefore
based on reference
reach comparisons
and state water
quality databases.
(0
3
Q.
x'
C/)
r^-
CD
£U
3
~n
c
D
O
r^-
o'
D
CO
QJ
3
CO
o
CO
-------
a
DO
0)
(A
(D
Q.
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
PHYSICOCHEMICAL
PARAMETER
Nutrients
Organic Carbon
MEASUREMENT
METHOD
Field test kits using
reagents reactions
Laboratory analysis
Laboratory analysis
PERFORMANCE STANDARD
FUNCTIONING
Meets water
quality standards
for designated use
Representative of
reference reach
Does not cause
eutrophication
Meet reference
reach OC
concentrations
FUNCTIONING-
AT-RISK
Meets water
quality standards
for designated
use, but is not
representative of
reference reach
Does not cause
eutrophication
Do not meet
reference reach
OC concentrations
NOT
FUNCTIONING
Does not meet
water quality
standards
Is not
representative of
the reference
reach
Causes
eutrophication
Do not meet
reference reach
OC concentrations
and are below a
predetermined
threshold
determined for
adequate organic
processing
SOURCE
Performance
standards have not
been developed for
these parameters
and are therefore
based on reference
reach comparisons
and state water
quality databases.
Performance
standards have not
been developed for
these parameters
and are therefore
based on reference
reach comparisons
and state water
quality databases.
(0
3
Q.
x'
C/)
r^>
CD
£U
3
~n
c
D
O
r^>
o'
D
CO
QJ
3
CO
o
-------
a
DO
0)
(A
(D
Q.
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
CO
o
Ul
BIOLOGY
PARAMETER
MEASUREMENT
PERFORMANCE STANDARD
SOURCE
Microbial
Communities
Macrophytes
Macro in vertebrate
Communities
METHOD
Periphyton Index of
Biological Integrity
(PIBI)
FUNCTIONING
>72
FUNCTIONING-
AT-RISK
61-71
NOT
FUNCTIONING
<60
Hill etal., 2000
(Journal)
Biological Indices
Mean Trophic Rank
(MTR)
Reference Index (Rl)
>65
-50 to 100
25-65
-70 to -50
<25
<-70
Holmes et al.,
1999 (Technical
Report)
Meilenger, 2005
(Journal)
Biological Indices
Family-Level Biotic
Index (FBI) Ranges
WVSCI Ranges
Virginia Stream
Condition Index
SOS Multimetric
Index
0.00-4.25
Excellent to Very
Good
68-100
Very Good to
Good
61-100
Exceptional to
Similar to Ref.
7-12
Acceptable
4.26-5.75
Good to Fair
45-61
Gray Area to Fair
40-60
Impaired Tier 1
N/A
5.76-10.00
Fairly Poor to Very
Poor
0-45
Poor to Very Poor
0-40
Impaired Tierl & 2
0-6
Unacceptable
Hilsenhoff, 1988
(Journal)
Gerritsen et al.,
2000;WVDEP
Burton J. and J.
Gerritsen, 2003
Engel and Voshell,
2002
(0
3
Q.
x'
C/)
r^>
CD
£U
3
~n
c
D
O
r^>
o'
D
CO
QJ
3
-------
a
5
DO
0)
(A
0)
3
(B
O
CD
APPENDIX A: STREAM FUNCTIONS PYRAMID (CONT.)
d. PERFORMANCE STANDARDS TABLE
BIOLOGY
PARAMETER
MEASUREMENT
PERFORMANCE STANDARD
SOURCE
Fish Communities
METHOD
FUNCTIONING
FUNCTIONING-
AT-RISK
NOT
FUNCTIONING
Biological Indices
Mid-Atlantic
Highlands IBI
Mid-Western Fish
Community IBI
IBI > 72
Good to Excellent
48-60
Good to Excellent
IBI = 56 to 71
Fair
40-44
Fair
IBI < 56
Poor
0-34
Poor to No Fish
McCormick et al.,
2001
Karretal., 1986
(0
3
Q.
x'
C/)
r^-
CD
£U
3
~n
c
D
O
r^-
o'
D
CO
QJ
3
CO
o
01
-------
Appendix B: Application Scenarios, Culvert Installations
APPENDIX B: APPLICATION SCENARIOS
APPLICATION: STREAM DEBIT AND CREDIT DETERMINATION SCENARIOS
The purpose of Appendix B is to illustrate how the Stream Functions Pyramid and its
associated measurement methods and performance standards can be used as an aid in
developing debit and credit determination methods for a variety of impact and restoration
scenarios. A description of the debit and credit determination method is provided in
Chapter 11, and the examples are shown below. These examples are not from actual
permit applications or restoration projects. Rather, they are generic, yet realistic scenarios
that are used to demonstrate how the debit and credit templates can be applied to a range
of scenarios. They are broad based and lack the specificity needed for an actual debit/
credit determination method. The purpose of these examples is to generate ideas about
how function-based parameters, measurement methods and performance standards can
be used in stream mitigation Standard Operating Procedures (SOPs).
The impact or debit scenarios include:
1. Culvert installations;
2. Channelization and bank hardening; and
3. Surface mining of high gradient streams.
The restoration or credit scenarios include:
1. Restoration of incised streams;
2. Restoration of stream flow for channels that have excessive water withdrawal;
3. Salmonid fish passage and habitat restoration; and
4. Restoration of high gradient, headwater streams.
Permitted Impact Scenarios (Debits)
Scenario 1: Culvert Installations
The following is a typical example of a new rural road and culvert installation with a
stable, healthy upstream watershed. The post-impact condition is based on typical results
of culvert installation and can be modified based on actual results or more quantitative
assessments. Table B1A shows the typical impacts associated with culvert installations.
Table B2a provides a narrative to support the data shown in table B1A, including the
rationale for selecting the parameters. Table B3a shows how debits could be calculated for
the permitted impact caused by the culvert installation.
Example Scenario
A permit application has been submitted to install a 60-inch diameter culvert for 500
feet of stream length. This is a standard culvert installation and the impact is predicted to
extend 200 feet downstream and 100 feet upstream of the culvert for a total impact
length of 800 feet. Upstream and downstream impacts are included based on hydraulic
modeling analysis and impacts associated with past installations in the region. If other
A Function-Based Framework » May 2012 307
-------
Appendix B: Application Scenarios, Culvert Installations
culvert installation approaches, e.g., floodplain culverts, are used, the impact length could
be reduced to the pipe length.
The upstream watershed has a drainage area of two square miles with a mix of agri-
cultural and suburban land uses. The rainfall/runoff relationship is moderately stable and
is not expected to significantly change in the near future. The channel is mildly incised
with a Bank Height Ratio of 1.1; however, the channel was straightened in the past,
creating a sinuosity of near 1.0. This has resulted in poor bed form diversity and a riffle-
pool percentage of 90:10 and pool depth ratios less than 1.5. A vegetative buffer of 50 feet
on each side of the channel is providing bank stability and cover, and is an effective filter
from adjacent land uses. As a result, the basic water quality is representative of reference
reach streams in the region; however, macroinvertebrate and fish communities do not
reflect reference conditions due to poor habitat.
Degradation is expected to occur for 200 feet downstream of the culvert. The Bank
Height Ratio will increase to 2.5 and the entrenchment ratio will decrease to 1.2. Bed
form diversity will remain poor and riffle dominated with a few shallow pools. Some
trees along the streambank are predicted to fall due to the high streambanks and large
volume of water now carried by the channel. Lateral erosion is predicted to be moderate.
Aggradation is expected to occur for 100 feet upstream of the culvert. The Bank Height
Ratio decreases to 1.0 and sand covers the riffles and fills the pools creating a plane bed.
The vegetation remains intact.
Referring to Table B1A, the pre-disturbance condition is a mix of Functioning, Func-
tioning-at-Risk, and Not Functioning scores for Levels 2-5. Therefore, the Functionality
Before Impact Category (Table BDlc) is Moderate. The post-disturbance condition,
shown on Table BDla, indicates that most parameters will be Not Functioning through
the culvert and downstream. Impacts are less upstream of the culvert with some param-
eters remaining as Functioning and a few becoming Not Functioning. Therefore, the
culvert and downstream section will be evaluated together as a 700 foot impact with
High Functional loss. The 100-foot upstream section has mostly Functioning scores
with a few Not Functioning scores and is assessed with a Moderate Functional Loss.
Scenario 2: Channelization and Bank Hardening
A permit application has been submitted to straighten and "improve" 1,000 linear feet
of stream channel. The "improvement" includes dredging (lowering) and widening the
channel to carry the 100-year discharge. The bed material will remain with natural
gravel, but the streambanks will be graded to a 2:1 slope and protected with rip rap.
Backyard lawns will extend outward from the top of the streambank.
The existing channel is moderately incised with a bank height ratio of 1.4. The chan-
nel is located in an alluvial valley and has a sinuosity of 1.3 and alternating riffles (70%)
and pools (30%). The pools are generally 2 to 2.5 times deeper than the riffles. A 10-foot
riparian buffer of mature hardwood trees is present on both sides of the channel, provid-
ing bank stability and cover over the channel.
A Function-Based Framework » May 2012 308
-------
a
5
DO
0)
(A
0)
3
(D
o
CD
TABLE BD1a DEBIT TEMPLATE 1: FUNCTIONAL LOSS DETERMINATION
Table BDla is completed by interpreting the information from the paragraph above and selecting parameters, measurement
methods and performance standards from Appendix A.
CO
o
u>
LEVELAND
CATEGORY
1 - Hydrology
2 — Hydraulics
3-
Geomorphology
PARAMETER
Not affected
Floodplain
Connectivity
Channel Evolution
Lateral Stability
Riparian
Vegetation
Bed Form
Diversity
Bed Material
Characterization
MEASUREMENT
METHOD
Bank Height
Ratio
Entrenchment
Ratio
Rosgen
BEHI/NBS
Rapid
Bioassessment
Protocol
Percent Riffle &
Pool
Pool Max Depth
Ratio
Size Class
Pebble Count
Analyzer
PRE-DISTUF
CONDITION
VALUE
1.1
>2.2
CorE
Low
8
90:10
< 1.5
Same as
upstream
IBANCE
RATING
Functioning
Functioning
Functioning
Functioning
Functioning-
at-Risk
Not
Functioning
Functioning-
at-Risk
Functioning
PREDICTED POST-DISTURBANCE
CONDITION
VALUE
1.0 - Upstream
2.5 - Downstream
> 2.2 - Upstream
1.2- Downstream
C or E upstream
G downstream
Low - Upstream
Moderate to high
downstream
0 through culvert
8 - Upstream
6 - Downstream
90:10 to 100%
riffle
< 1.2
Finer- upstream
of culvert
Same -
Downstream
RATING
Functioning upstream;
Not Functioning through
culvert and downstream
Functioning upstream;
Not Functioning through
culvert and downstream
Functioning upstream;
Not Functioning through
culvert and downstream
Functioning upstream;
Not Functioning
Downstream
Functioning upstream;
Not Functioning through
culvert and downstream
Not Functioning
Not Functioning
Not Functioning
upstream and culvert
Functioning
Downstream
(D
3
Q.
x'
DO
o
C/)
o
CD
D
QJ
^
o'
w
O
c_
<
CD
r^-
o'
-------
TABLE BD1a DEBIT TEMPLATE 1: FUNCTIONAL LOSS DETERMINATION (CONT.)
a
CO
0)
(A
(0
Q.
0)
3
i
o
3-
CD
LEVELAND
CATEGORY
4-
Physicochemical
5 - Biology
PARAMETER
Water Quality
Macroinvertebrate
Communities
Fish Communities
MEASUREMENT
METHOD
Dissolved
Oxygen (mg/l)
Hilsenhoff Biotic
Index (HBI)
Index of Biotic
Integrity (IBI)
PRE-DISTURBANCE
CONDITION
VALUE
Same as
upstream
6
Poor
RATING
Functioning
Not
Functioning
Not
Functioning
PREDICTED POST-DISTURBANCE
VALUE
Lower than
upstream
8
Poor
RATING
Not Functioning
Not Functioning
Not Functioning
3
Q.
x'
DO
o
c/)
o
CD
QJ
^
o'
o
c_
CD
r^-
o'
CO
o
-------
Appendix B: Application Scenarios, Culvert Installations
TABLE BD1b DEBIT TEMPLATE 2: PRE- AND POST-DISTURBANCE CONDITIONS AND RATIONALE
Describe Pre- and Post-Disturbance Condition and Rationale for Selecting Parameters
Hydrology - The watershed hydrology is stable and is not expected to change. Therefore,
Hydrology parameters were not selected.
Hydraulics - The existing channel is mildly incised and has access to a wide alluvial
floodplain, i.e., there is floodplain connectivity. In this example, the culvert will likely
cause channel incision downstream of the culvert, and bank height ratios are likely to
increase, causing a Not Functioning score. The culvert will provide grade control for the
upstream channel and the bank height ratio may decrease because of aggradation.
Geomorphology - The existing channel is a stable Rosgen C or E stream type that has
been straightened, i.e., in this case, a low sinuosity will not change the stream type. The
streambanks are stable with minimal bank erosion. There is a riparian buffer of
bottomland hardwood trees. The upstream watershed and stream reach is stable. The
bed form is riffle dominated due to past channelization. The channel is predicted to
remain a C stream type upstream and change to a Gc downstream. Lateral stability will
decrease from Functioning to Not Functioning due to channel incision downstream of the
culvert. The riparian vegetation is totally removed along the length of the culvert and,
therefore, would score Not Functioning. However, the riparian buffer remains intact
upstream of the culvert (Functioning). Bed form diversity is altered upstream and
downstream of the culvert. Upstream of the culvert, pools fill in with sediment during
aggradation. This decreases depth variability and shifts the substrate distribution curve
towards sand size material, which in this case is finer than the upstream riffle material.
Channel incision downstream, along with a decrease in Width/Depth ratio, causes the
riffles to erode and drain the pools. This creates a plane bed form.
Physicochemical - Since the upstream watershed is stable and there is an existing
bottomland forest, the basic water quality parameters are Functioning. The only water
quality parameter selected to measure is Dissolved Oxygen (DO). The other parameters
will likely not be impacted to the point where their functioning score would be
significantly different from the upstream reference reach or violate water quality
standards. Due to the reduction in depth variability and bed form diversity, DO may shift
from Functioning to Not Functioning.
Biology - Due to poor bed form diversity and riparian vegetation prior to culvert
installation, macroinvertebrate and fish communities are Not Functioning before and after
the disturbance.
A Function-Based Framework » May 2012 311
-------
Appendix B: Application Scenarios, Culvert Installations
TABLE BD1c DEBIT TEMPLATE 3: DEBIT REQUIREMENTS
PRE-
POST-DISTURBANCE CONDITION
DISTURBANCE
CONDITION
Low (Mix of
Functioning-
at-Risk and
Not
Functioning)
Moderate (Mix
of Functioning,
Functioning-
at-Risk, and
Not
Functioning)
High
(Functioning)
NO FUNCTIONAL
LOSS
(Post-
disturbance
condition
matches
pre-disturbance
condition)
No mitigation
required
LOWTO MODERATE
FUNCTIONAL LOSS
Greater number of
Function ing-at-Risk
and Not
Functioning Scores
1.1 to 1.2
Loss of Functioning
scores and/or
greater number of
Function ing-at-Risk
and Not
Functioning Scores
1.3 to 1.5
Mix of Functioning,
Functioning-at-
Risk, and Not
Functioning Scores
1.7 to 1.9
MODERATETO
HIGH FUNCTIONAL
LOSS
Mostly Not-
Functioning
Scores
1.2 to 1.3
Mix of
Functioning-at-
Risk and Not
Functioning
Scores
1.5 to 1.7
Mix of
Functioning-at-
Risk and Not
Functioning
Scores
2.0
DEBIT
ADJUSTMENT
(+/-)
0.1
0.1
0.2
The overall calculations are shown below. The total debits calculated for this impact is 1260.
REACH
Upstream
Culvert and Downstream
Total
LENGTH CATEGORY FROM DEBIT RATIO TOTAL
(FT) TABLE B3 (DEBITS/FT)
100
700
800
Moderate/
Moderate
Moderate/ High
1.4
1.6
100X1.4 =
700X1.6 =
1120 + 140
140
1120
= 1260
The upstream watershed is rural to suburban and moderately stable without major
point sources of pollution. Nonpoint source pollution includes runoff from existing yards,
homes, and secondary roads. These land uses have not caused significant increases to the
rainfall/runoff relationship. A healthy community of benthic organisms and small native
fish lives in the stream. Temperature and DO levels are representative of reference streams.
A Function-Based Framework » May 2012
312
-------
a
5
DO
0)
(A
0)
3
i
o
3-
CD
TABLE BD2a DEBIT TEMPLATE 1: FUNCTIONAL LOSS DETERMINATION
Table BD2a is completed by interpreting the information from the paragraph above and selecting parameters, measurement
methods and performance standards from Appendix A.
LEVELAND
CATEGORY
1 - Hydrology
2 - Hydraulics
4-
Physicochemical
5 - Biology
PARAMETER
Not affected
Floodplain
Connectivity
Riparian
Vegetation
Bed Form
Diversity
Water Quality
Macroinvertebrate
Communities
Fish Communities
MEASUREMENT
METHOD
Bank Height Ratio
Average buffer
width
Percent Riffle &
Pool
Pool Max Depth
Ratio
Dissolved Oxygen
Temperature
Family Level Biotic
Index (FBI)
Index of Biotic
Integrity (IBI)
PRE-DISTURBANCE
CONDITION
VALUE
1.4
10
70:30
2-2.5
Same as
reference
Same as
reference
4
Good
RATING
Functioning-
at-Risk
Not
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
PREDICTED POST-DISTURBANCE
CONDITION
VALUE
>2
0
90:10 to 100% riffle
< 1.2
Is not representative
of reference reach
and does not meet
species requirements
Is not representative
of reference reach
and does not meet
species requirements
8
Poor
RATING
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
(D
3
Q.
x'
DO
o
QJ
C/)
o
CD
D
QJ
^
o'
w
O
^
QJ
QJ
r^-
5'
D
QJ
DO
QJ
QJ
Q.
CD
CQ
CO
CO
-------
Appendix B: Application Scenarios, Channelization and Bank Hardening
TABLE BD2b DEBIT TEMPLATE 2: PRE-AND POST-DISTURBANCE CONDITIONS AND RATIONALE
Describe Pre- and Post-Disturbance Condition and Rationale for Selecting Parameters
Hydrology - The watershed hydrology is stable and is not expected to change. Therefore,
Hydrology parameters were not selected.
Hydraulics - The pre-disturbance Bank Height Ratio was provided in the summary report
as 1.4, which is Functioning-at-Risk. The predicted post-disturbance ratio was not
provided; however, it was stated that the channel would be designed to carry the 100-yr
discharge. A Bank Height Ratio much greater than 2.0 is required to carry that amount of
water and would be Not Functioning for floodplain connectivity.
Geomorphology - Information about the width of the riparian vegetation and bed form
diversity (percent riffle/pool and depth variability) were provided in the summary report.
Due to a narrow buffer width, the pre-disturbance condition is Not Functioning for
riparian vegetation. Bed form diversity is Functioning. In order to transport water as
quickly as possible, it is predicted that the bufferwill be maintained as rip rap and maybe
grass. Therefore, the riparian vegetation will remain Not Functioning. The channel will
also be straightened and designed with a uniform cross section and profile, eliminating
pool features. Therefore, a Not Functioning score is given to both bed form diversity
measures.
Physicochemical - The summary report stated that the pre-disturbance DO and
temperature levels matched the reference reach, which is a Functioning score. The post-
disturbance condition is predicted to be Not Functioning due to the lack of buffer and pool
features, and an overly wide channel, all of which contribute to higher stream
temperatures and therefore lower DO levels.
Biology - The summary report states that a healthy community of benthic organisms and
small native fish live in the stream pre-disturbance. Due to the removal of pool habitat
and the decline in water quality, the post-disturbance score is Not Functioning.
Referring to Table BD2a; the majority of the pre-disturbance parameters are Function-
ing. The riparian vegetation is the only Not Functioning parameter and Floodplain Con-
nectivity is Functioning-at-Risk. Using Table BD2c; this provides a Functionality Before
Impact score of Moderate, but it would be the high end of Moderate. Table BD2a shows
that the predicted post-disturbance condition is mostly Not Functioning with only one
measurement method, conductivity, scoring a Functioning-at-Risk. This equals a High
Functional Loss on Table BD2c. A Moderate/High yields a debit ratio range of 1.5 to 1.7.
Since the pre-disturbance condition was on the higher end of Moderate, the 1.7 ratio is
used. Therefore, the total debits for this site is 1,000 linear feet X 1.7 = 1,700 debits.
A Function-Based Framework » May 2012 314
-------
Appendix B: Application Scenarios, Channelization and Bank Hardening
TABLE BD2c DEBIT TEMPLATE 3: DEBIT REQUIREMENTS
PRE-
POST-DISTURBANCE CONDITION
DISTURBANCE
CONDITION
Low (Mix of
Functioning-at-
Risk and Not
Functioning)
Moderate (Mix
of Functioning,
Functioning-at-
Risk, and Not
Functioning)
High
(Functioning)
NO FUNCTIONAL
LOSS
(Post-
disturbance
condition
matches
pre-disturbance
condition)
No mitigation
required
LOWTO MODERATE
FUNCTIONAL LOSS
Greater number of
Functioning-at-Risk
and Not
Functioning Scores
1.1 to 1.2
Loss of Functioning
scores and/or
greater number of
Functioning-at-Risk
and Not
Functioning Scores
1.3 to 1.5
Mix of Functioning,
Functioning-at-
Risk, and Not
Functioning Scores
1.7 to 1.9
MODERATETO
HIGH
FUNCTIONAL
LOSS
Mostly Not-
Functioning
Scores
1.2 to 1.3
Mix of
Functioning-at-
Risk and Not
Functioning
Scores
1.5 to 1.7
Mix of
Functioning-at-
Risk and Not
Functioning
Scores
2.0
DEBIT
ADJUSTMENT
(+/-)
0.1
0.1
0.2
Scenario 3: Surface Mining of High Gradient Streams
A permit has been submitted to impact 10,000 feet of headwater streams related to a
large surface mine. The streams are all located in v-shaped and colluvial valleys and are
classified as Rosgen A and B stream types. The streams are vertically and laterally stable
with appropriate access to a floodprone area. The bank height ratio is 1.0 and the en-
trenchment ratio is 1.5. Bed form diversity is characterized by step-pools comprised of
cobbles, boulders and large woody debris (LWD). Pool depths are typically greater than
1.5 times the mean riffle depth. Pool to pool spacing is less than 4 times the bankfull
width. The riparian buffer spans the entire width of the valley and includes most of the
hillslope as well. Buffer composition is characterized by a mature hardwood forest that
totally covers the channel with an appropriate understory and minimal invasive species.
Water quality is excellent with temperature, DO, pH, and conductivity levels representa-
tive of reference conditions. Large woody debris and smaller sticks and leaves can be
found in the channel and on the floodprone area in quantities that are representative of
reference conditions. Macroinvertebrate and small fish communities are also representa-
tive of reference conditions for small headwater channels.
A Function-Based Framework » May 2012
315
-------
Appendix B: Application Scenarios, Surface Mining of High Gradient Streams
The permitted surface mining operation requires the complete removal of the natural
stream channel and associated riparian vegetation during mining. Stormwater BMPs,
erosion control devices, and drainage channels will be constructed to comply with federal
and state regulations; however, these practices do not prevent the loss of many stream
functions. The new drainage channels will carry a 100-year discharge, which is much
larger than the bankfull discharge. The channel bed and banks will be stabilized with rip
rap. A uniform channel dimension and profile will be designed and constructed. Tempo-
rary vegetation will be established to provide erosion control. The post-disturbance
water quality is predicted to increase conductivity and temperature and reduce pH and
DO levels. The system will be devoid of LWD and smaller organic material. Macroinver-
tebrate and fish communities will not be representative of reference conditions.
From Table BD3a, the pre-disturbance condition is high with Functioning scores in all
five Levels. This equals a High for Functionality Before Impact in Table BD3c. Again
from Table BD3a, the post-disturbance condition shows mostly Not Functioning scores in
all five Levels. This equals a High Functional Loss in Table BD3c. A High/High yields a
debit ratio of 2.0 debits per foot. Therefore, the total debits are 10,000 ft X 2.0 debits/ft =
20,000 debits.
Stream Mitigation Scenarios (Credits)
The credit examples below represent restoration projects that are offsite from the
permitted impact. A description of the credit determination method is provided in Chap-
ter 11. For the scenarios below, a variety of credit determination methods are used to: 1)
show different approaches to developing stream credits and 2) reflect the sometimes
unique characteristics of a site, e.g., water withdrawal and dam removal. It may be
helpful to review all of the credit determination methods in order to see the variety of
approaches that are used.
The restoration or credit scenarios include:
1. Restoration of incised channels in alluvial valleys;
2. Restoration of stream flow for channels that have excessive water withdrawal;
3. Salmonid fish passage and habitat restoration; and
4. Restoration of high gradient, headwater streams.
Scenario 1: Restoration of Incised Channels in Alluvial Valleys
Channelization and subsequent incision is one of the biggest contributors to stream
impairment. Incised channels can be found throughout the US and lead to excessive
sedimentation from eroding bed and banks, which smothers aquatic habitats and reduces
bed form diversity. These channels are often classified as unstable Rosgen Gc and F
stream types. Restoration methods often follow Rosgen's Priority Levels of restoring
incised channels (Rosgen, 1997), which is described in Chapter 3. The template below
deviates from this approach by specifically focusing on the parameters from the Stream
Functions Pyramid that relate to functions. This provides a more direct method for
A Function-Based Framework » May 2012 316
-------
Appendix B: Application Scenarios, Surface Mining of High Gradient Streams
describing functional lift. However, the same restoration methods that are used to imple-
ment Rosgen's Priority Levels can be used here.
Example Scenario
A mitigation provider has secured a restoration project reach of 5,000 feet. The site is
located immediately downstream from a state forest and the entire upstream watershed
is forested and stable. The existing reach is located on a beef farm and the cattle have full
access to the channel. The stream is highly incised with a bank height ratio of 3.0;
however, there is a bedrock knickpoint at the upstream end of the project. The stream is
not incised upstream of the knickpoint. The channel is very straight and devoid of bed
form diversity. Over 90% of the bed is riffle. There is no buffer and bank erosion is
prevalent throughout the reach. Because of these impacts, there are few aquatic organ-
isms living in the channel. Stream temperatures are high and DO levels are low, based on
a comparison to the upstream reference reach.
Because the upstream watershed is very healthy, the mitigation provider proposes to
complete a Restoration 1 approach. As a review, the restoration options are shown below.
A description of each is provided in Chapter 11.
Restoration 1 - Reach scale restoration, connected to a healthy watershed
Restoration 2 - Reach scale restoration, variable upstream watershed conditions
For this project, a Rosgen Priority Level 1 restoration approach is proposed. A new
meandering channel will be constructed and reconnected to the original floodplain at the
bedrock knickpoint. The floodplain is 50 times wider than the channel and a sinuosity of
1.4 is used. The new stream type is a C4. The design includes alternating riffles and
pools, with the pools containing root wads with cover logs and other structures to
provide stability, LWD and cover. The depth variability includes a percent riffle:pool ratio
of 70:30 and maximum pool depth ratios greater than 2.0. A meander width ratio of 7 is
used with a buffer that extends for 25 feet beyond the belt width. The old channel (prior
to restoration) is filled with material excavated for the new channel with large portions
converted into riparian wetlands. Additional wood is used to create wetland complexity
and provide habitat for salamanders, frogs and other amphibians. Due to the excellent
health of the upstream watershed and the structural improvements to the project reach,
DO and temperature levels return to reference condition by the fourth year after restora-
tion construction. The aquatic macroinvertebrate and fish communities return to refer-
ence condition by year 5.
Table BCla shows that the pre-restoration condition for all parameters was Not Func-
tioning and that the predicted post-restoration condition improved all of those param-
eters to Functioning score. Using Table BClc, this would yield a Maximum Lift, and 0.8
to 1.0 credits per foot could be assigned to the restored channel length. Based on the high
quality of this example, a ratio of 1.0 is selected. The restored channel length is 5,000 feet
X 1.4 sinuosity = 7,000 feet. Total credits = 7,000 ft X 1.0 = 7,000 credits.
A Function-Based Framework » May 2012 317
-------
DO
0)
(A
0)
3
i
o
3-
CD
TABLE BD3a DEBIT TEMPLATE 1: FUNCTIONAL LOSS DETERMINATION
Table BD3a is completed by interpreting the information from the paragraph above and selecting parameters, measurement
methods and performance standards from Appendix A.
CO
00
LEVELAND
CATEGORY
1 - Hydrology
2 - Hydraulics
3-
Geomorphology
PARAMETER
Runoff
Flow Duration
Floodplain
Connectivity
Ground water/
Surface-Water
Interaction
Riparian
Vegetation
Bed Form
Diversity
Large Woody
Debris
Bed material
characterization
MEASUREMENT
METHOD
N/A
N/A
Bank Height Ratio
Entrenchment
Ratio
N/A
RBP
Pool to Pool
Spacing
Pool Max Depth
Ratio
LWDI
RSI
PRE-DISTURBANCE
CONDITION
VALUE
N/A
N/A
1.0
1.4
9
<4
> 1.5
Same as
reference
condition
<70
RATING
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
PREDICTED POST-DISTURBANCE
CONDITION
VALUE
N/A
N/A
>2
1.2
N/A
0
>4
<1.2
Does not equal
reference condition
and is not trending
in that direction
>85
RATING
Not
Functioning
Not
Functioning
Not
Functioning
Functioning-
at-Risk
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
(D
3
Q.
x'
DO
o
03
C/)
o
CD
D
QJ
^
o'
w
C/)
c
o
CD
CO
O
O
S
Q.
CT>'
D
r^-
C/)
r^-
CC
QJ
3
CO
-------
TABLE BD3a DEBIT TEMPLATE 1: FUNCTIONAL LOSS DETERMINATION (CONT.)
a
CO
0)
Vt
(0
Q.
0)
3
i
o
3-
CD
CO
to
LEVELAND
CATEGORY
4-
Physicochemical
5 - Biology
PARAMETER
Water Quality
Macro invertebrate
Communities
Fish Communities
MEASUREMENT
METHOD
Dissolved Oxygen
Temperature
Conductivity
PH
Family-Level
Biotic Index (FBI)
Index of Biotic
Integrity (IBI)
PRE-DISTURBANCE
CONDITION
VALUE
Same as
reference
Same as
reference
Same as
reference
Same as
reference
4
Good
RATING
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
PREDICTED POST-DISTURBANCE
CONDITION
VALUE
Is not
representative of
reference reach
and does not meet
species
requirements
Is not
representative of
reference reach
and does not meet
species
requirements
Is not
representative of
reference reach
and does not meet
species
requirements
Is not
representative of
reference reach
and does not meet
species
requirements
8
Poor
RATING
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
3
Q.
x'
DO
o
03
C/)
o
CD
D
QJ
^
o'
w
C/)
c
o
CD
CO
o
O
Q)
Q.
C/)
r^-
CC
QJ
3
CO
-------
Appendix B: Application Scenarios, Surface Mining of High Gradient Streams
TABLE BD3b DEBIT TEMPLATE 2: PRE- AND POST-DISTURBANCE CONDITIONS AND RATIONALE
Describe Pre- and Post-Disturbance Condition and Rationale for Selecting Parameters
Hydrology - Performance standards have not been provided for Runoff and Flow Duration
parameters. However, they are included in this example because surface mining
negatively impacts these function-based parameters. Runoff often increases and flow
duration decreases to Not Functioning levels, based on a comparison to reference or
pre-mining conditions.
Hydraulics - These high-gradient streams do not have floodplains, but they do have
floodprone areas that should be accessed at flows greater than bankf ull. The post-
disturbance bank height ratio is not provided in the report summary; however, the value
will be well over 2 to carry the 100-yr discharge. The entrenchment ratio is predicted to
decrease slightly as the bankfull channel is replaced with a large trapezoidal channel.
Groundwater/surface-water interaction was also selected, even though it doesn't have a
performance standard. The pre-disturbance condition would likely include Functioning
groundwater/surface-water interaction. If the surface mining operation raises the channel
and/or places the channel on fill, these processes will become Not Functioning.
Geomorphology - A mature forest provides a Functioning score for riparian vegetation
priorto the disturbance. The riparian vegetation becomes Not Functioning after mining
because the vegetation is totally removed. The temporary vegetation does not provide
the same stability, cover and water quality as the mature forest. Bed form diversity
measures all changes from Functioning to Not Functioning because the drainage channels
are not designed with reference condition values of pool-pool-spacing and depth
variability. Large woody debris is expected to become Not Functioning because the forest
will be cleared (removing the wood source) and the design channels do not incorporate
wood. Bed material will move from Functioning to Not Functioning because native
mixtures of colluvium will be replaced by rip rap.
Physicochemical - All water quality measurement methods shift from Functioning to Not
Functioning because they no longer resemble reference conditions. Dissolved oxygen and
pH will likely decrease and conductivity and possibly temperature will increase.
Biology - The macroinvertebrate and fish communities also shift from Functioning to Not
Functioning because of all the impacts to the supporting functions. The Hydrology,
Hydraulic and Geomorphology functions cannot support the water quality functions that
in turn support the Biology functions.
A Function-Based Framework » May 2012 320
-------
Appendix B: Application Scenarios, Surface Mining of High Gradient Streams
TABLE BD3c DEBIT TEMPLATE 3: DEBIT REQUIREMENTS
PRE-
DISTURBANCE
CONDITION
POST-DISTURBANCE CONDITION
NO FUNCTIONAL
LOSS
LOWTO MODERATE
FUNCTIONAL LOSS
MODERATETO I DEBIT
HIGH FUNCTIONAL ADJUSTMENT
Low (Mix of
Functioning-
at-Risk and
Not
Functioning)
Moderate (Mix
of Functioning,
Functioning-
at-Risk, and
Not
Functioning)
(Post-
disturbance
condition
matches
pre-disturbance
condition)
No mitigation
High required
(Functioning)
Greater number of
LOSS
Mostly Not
Functioning-at-Risk Functioning
and Not Scores
Functioning Scores
1.1 to 1.2
Loss of Functioning
scores and/or
greater number of
Functioning-at-Risk
and Not
Functioning Scores
1.3 to 1.5
Mix of Functioning,
Functioning-at-
Risk, and Not
Functioning Scores
1.7 to 1.9
1.2 to 1.3
Mix of
Functioning-at-
Risk and Not
Functioning
Scores
1.5 to 1.7
Mix of
Functioning-at-
Risk and Not
Functioning
Scores
2.0
(+/-)
0.1
0.1
0.2
Scenario 2: Restoration of Stream Flow for Channels That Have Excessive
Water Withdrawal
The following example is a common stream impairment in the western U.S. where
water supply is scarce. In these systems, baseflow often diminishes in a downstream
direction due to excessive water withdrawals for drinking water, irrigation, etc. This can
have a negative effect on baseflow duration and stream biota. In many cases, water
withdrawal can convert a perennial stream to intermittent, with the streambed being
totally dry in the summer months.
The literal restoration of stream flows, where water is returned to the channel and not
used for irrigation or other uses, requires policy decisions that do not apply to the Stream
Functions Pyramid. However, there are cases where stream restoration activities may be
able to improve base flow conditions. The example below focuses on a scenario that can
benefit from alterations to the stream channel (morphology) rather than an example
where water is returned to the channel by manipulating the hydrologic cycle.
A Function-Based Framework » May 2012
321
-------
DO
0)
(A
0)
3
i
o
3-
CD
TABLE BC1a CREDIT TEMPLATE 1: FUNCTIONAL LIFT DETERMINATION
Table BCla is completed by interpreting the information from the paragraphs above and selecting parameters, measurement
methods and performance standards from Appendix A.
LEVELAND
CATEGORY
1 - Hydrology
2 - Hydraulics
3 - Geomorphology
PARAMETER
N/A
Floodplain
Connectivity
Large Woody
Debris Storage
and Transport
Channel
Evolution
Bank Migration/
Lateral Stability
MEASUREMENT
METHOD
Bank Height Ratio
Entrenchment Ratio
LWDI
Rosgen Stream Type
Succession
Scenarios
BEHI/NBS
PRE-DISTURBANCE CONDITION
VALUE
3.0
1.1
LWDI does not
equal LWDI of
reference reach
GorF4
High and Very
High BEHI Curve
Moderate to
Extreme NBS
RATING
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
PREDICTED POST-DISTURBANCE
CONDITION
VALUE
1.0
>2.2
LWDI equals
LWDI of
reference reach
C4
Low BEHI Curve
Very low to
Moderate NBS
RATING
Functioning
Functioning
Functioning
Functioning
Functioning
(D
3
Q.
x'
DO
o
C/)
o
CD
D
QJ
^
o'
CD
CO
O
co'
CD
Q.
O
CO
CO
-------
TABLE BC1a CREDIT TEMPLATE 1: FUNCTIONAL LIFT DETERMINATION (CONT.)
a
CO
0)
Vt
(0
Q.
0)
3
(0
o
CD
CO
IV)
CO
LEVELAND
CATEGORY
3 - Geomorphology
4- Physicochemical
5 - Biology
PARAMETER
Riparian
Vegetation
Bed Form
Diversity
Basic Water
Chemistry
Benthic
Fish
Communities
MEASUREMENT
METHOD
Buffer Width (ft) from
Meander Belt Width
Buffer Density,
Composition, Age,
Growth and Canopy
Density
Percent Riffle and
Pool
Depth Variability
(Pool Max Depth
Ratio)
Temperature
Dissolved Oxygen
Family-level
Biological Index (FBI)
McCormick Index of
Biological Integrity
PRE-DISTURBANCE CONDITION
VALUE
0
Significantly less
functional than
reference reach
condition; little or
no potential to
improve without
significant
restoration effort.
90:10
<1.2
Project Reach is
statistically
different (higher)
than reference
reach.
Project Reach is
statistically
different (lower)
than reference
reach.
8
50
RATING
Not
Functioning
No
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
PREDICTED POST-DISTURBANCE
CONDITION
VALUE
MWRof7and
additional width
of 25 ft
By year 5,
riparian
vegetation is on
a trajectory to
become similar
to the upstream
reference
condition.
70:30
>2
Project Reach is
not statistically
different than
reference reach
by year 4.
Project Reach is
not statistically
different than
reference reach
by year 4.
2
75
RATING
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
3
Q.
x'
DO
o
(/)
o
03
5'
CO
O
Q)
5'
o
O
co'
CD
Q.
O
CO
-------
Appendix B: Application Scenarios, Restoration of Incised Channels
TABLE BC1b CREDIT TEMPLATE 2: PRE-AND POST-RESTORATION CONDITIONS AND RATIONALE
Describe Pre- and Post-Restoration Condition and Rationale for Selecting Parameters
Hydrology - The watershed hydrology is stable and is not expected to change. Therefore,
Hydrology parameters were not selected.
Hydraulic - The existing channel is severely incised (Bank Height Ratio of 3) and does not
have access to a wide alluvial floodplain. The channel will be reconnected to the
floodplain through a Rosgen Priority Level 1 Restoration. The Bank Height Ratio will be
reduced to 1.0 and all flows greater than bankfull will spread onto a floodplain that is 50
times wider than the channel, making the entrenchment ratio well over 2.2.
Geomorphology- The existing channel is an incised Gc or F4 channel. The stream is
straight and incised with poor bed form diversity and severe bank erosion. The valley is
wide without constraints, but the riparian buffer is very thin. The new channel will include
a sinuosity of 1.4, which will reduce stream velocity and help support bed form diversity.
The additional wood structures will also help create deeper pools and better depth
variability. A wide riparian buffer will be planted to help maintain bank stability, provide
cover, and regulate water and air temperatures. Large woody debris will be incorporated
into the channel to provide further bed form complexity and habitat. The predicted result
is that all of the Geomorphology parameters and associated measurement methods
shown in Table B4a will shift from Not Functioning to Functioning.
Physicochemical - Since the upstream watershed is nearly pristine, water quality entering
the project reach is very good. Temperature does increase through the project reach due
to lack of vegetative cover and the high channel width associated with G/F channels,
creating Not Functioning scores pre-restoration. The lack of bed form diversity and high
temperatures cause low DO levels. These two parameters are selected because they are
impaired but can likely be improved with restoration efforts. The restoration activities
under the Geomorphology category, along with healthy watershed, will provide the
channel form necessary to reduce water temperature and increase DO levels. This is
primarily through the increase in bed form diversity (improved riffles) and the
establishment of a wide riparian buffer. Since these parameters and measurement
methods require an established buffer in addition to proper channel form, they are
predicted to take 4 years to reach a Functioning score.
Biology - Similar to the Physicochemical parameters, the Biology conditions entering the
project reach are Functioning, but become degraded due to the reach conditions.
Macroinvertebrate and Fish Community parameters are selected because the reach scale
activities in combination with the high quality watershed indicate a high potential for
restoring these parameters to a Functioning level. The improvement to Pyramid Levels 2-4,
along with the health of the upstream watershed, will provide the channel form and processes
necessary to support Functioning macroinvertebrate and fish communities. However, since
the water quality parameter will not reach a Functioning level until year 4, it is predicted to
take 5 years to reach a Functioning score for macroinvertebrate and fish communities.
A Function-Based Framework » May 2012 324
-------
Appendix B: Application Scenarios, Water Withdraw!
TABLE BC1c CREDIT TEMPLATE 3: CREDIT CALCULATIONS
RESTORATION 1
CREDIT CATEGORIES
PRE-RESTORATIOP
CONDITION
POST-RESTORATION
CONDITION
CREDITS
PER FOOT
Maximum Lift
All parameters in Pyramid
Levels 2 and 3 have Not
Functioning scores.
Parameters in Levels 4
and 5 are Not Functioning
or Functioning-at-Risk.
Functioning scores for
Levels 1-5
0.8 to 1.0
Moderate Lift
Mix of Not-Functioning
and Functioning-at-Risk
scores for parameter
Levels 2 through 5
Functioning scores for
Levels 1-5
0.6 to 0.8
Low Lift
Mix of Not-Functioning,
Functioning-at-Risk and
Functioning scores for
parameter Levels 2
through 5
Functioning scores for
Levels 1-5
0.4 to 0.6
Example Scenario
A 5,000 foot restoration project has been secured to improve base flow conditions that
have been impacted by excessive water withdrawals. The project reach is in an agricul-
tural setting and the withdrawals are used for irrigation. The stream is in a wide alluvial
valley and is approximately 75 feet wide. The sinuosity is 1.3, which is appropriate given
the stream and valley condition. The channel is moderately incised with a Bank Height
Ratio of 1.2. There is a 10-foot buffer with a mixture of cottonwoods and some herba-
ceous vegetation; however, beyond that is cropland. The moderate incision and lack of
buffer has created localized bank erosion in the outside of several meander bends. The
streambed and banks are comprised of well-graded (poorly sorted) gravel, sand, and
cobble with the median particle size in the gravel range. Bed form diversity is moderate
with pools existing in the outside of the meander bends; however, the overall depth
variability and complexity is low. This is primarily caused by the lack of baseflow and
LWD. When baseflow is present, basic water quality parameters of DO, temperature and
pH are representative of reference conditions. However, due to the adjacent cropland, lack
of buffer and incision, nitrate-nitrogen levels are higher than reference conditions, but not
high enough to cause eutrophication. Macroinvertebrate and fish communities reflect
reference reach conditions in the winter, but not the summer when baseflow is low or absent.
The goal of the restoration project is to improve baseflow duration in the summer
months, reduce streambank erosion, and to reduce nitrate-nitrogen levels. A restoration
approach is proposed to work with the existing channel alignment since the overall
planform geometry is stable and to save the existing cottonwoods that help provide bank
A Function-Based Framework » May 2012
325
-------
Appendix B: Application Scenarios, Water Withdraw!
stability, cover and denitrification. The dimension of the channel will be modified to
create a smaller baseflow channel within the existing bankfull channel. In addition,
in-stream structures will be used to raise the stream bed and thereby reduce the Bank
Height Ratio to 1.0. The objective with this approach is to improve groundwater/surface-
water interaction by raising the water table and increasing bank storage in the winter
months. Gravel material will be excavated from the pools and used to construct the
riffles. Cross vanes will be used to raise the bed, provide grade control and increase the
number of pools. Large woody debris will also be introduced into the channel to further
aid in raising the bed and creating pools. The increased number of pools in conjunction
with the improved groundwater/surface-water interaction is predicted to improve base-
flow. Bioengineering and LWD will be used to stabilize the eroding streambanks. In
addition, the buffer will be expanded to 100 feet on both sides of the stream. This will
provide a buffer to treat nutrient (nitrogen) runoff and create favorable conditions for
denitrification. These changes are predicted to return water quality, nutrient, macroinver-
tebrate and fish communities to reference conditions.
Table BC2c shows the credit ratios in credits per foot for restoration projects associated
with excessive water withdrawals. The rows represent the function scores from the
pre-restoration condition provided in Table BC2a. The columns are from the post-restora-
tion scores in Table BC2a. Credits are only provided for functional lift, so if the post-res-
toration condition is equal to or less than the pre-restoration condition, credits are not
provided. In addition, categories are assigned to the different levels of functional lift.
Projects with low pre-restoration functionality scores are eligible for restoration credits,
moderate pre-restoration scores for enhancement, and high pre-restoration scores for
preservation. This is shown in Table BC2a.
For this example, the Before Functionality score is Low — Flow duration is Not Func-
tioning, there is a mix of Functioning-at-Risk and Not Functioning scores for Levels 2-4 and
the Level 5 scores are Not Functioning. All post-restoration scores are Functioning, so this
equals a High After Functionality score. A Low/High result yields a credit ratio of 1.0.
Therefore, the total amount of credits for this site is 5,000 ft X 1.0 credits/ft = 5,000 credits.
Scenario 3: Salmonid Fish Passage and Habitat Restoration
The restoration of salmonid fish passage and habitat is a major focus in the Pacific
Northwest and to a lesser degree in the Atlantic Northeast. In the Northwest, the con-
struction and maintenance of dams have had a negative impact on the migration of
salmonids from the ocean to headwater spawning areas. In addition, fish habitat has been
reduced from logging and other impacts that have created channel incision and changes
to bed material size and composition.
A Function-Based Framework » May 2012 326
-------
TABLE BC2a CREDIT TEMPLATE 1: FUNCTIONAL LIFT DETERMINATION
a
CO
0)
(A
(0
Q.
0)
3
i
o
3-
CD
LEVELAND CATEGORY
1 - Hydrology
2 - Hydraulics
PARAMETER
Flow Duration
Floodplain
Connectivity
Groundwater/
Surface-Water
Interaction
Large Woody
Debris Storage
and Transport
Bank Migration/
Lateral Stability
Riparian
Vegetation
MEASUREMENT
METHOD
N/A
Bank Height
Ratio
N/A
LWDI
BEHI/NBS in
meander bends
Average Buffer
Width (ft)
Buffer Density,
Composition,
Age, Growth
and Canopy
Density
PRE-RESTORATIONI
VALUE
1.2
LWDI does not
equal LWDI of
reference reach.
High and Very
High BEHI Curve
Moderate to
Extreme NBS
10
Significantly
less functional
than reference
reach condition;
little or no
potential to
improve without
significant
restoration
effort.
:ONDITION
RATING
Not
Functioning
Functioning
Functioning-
at-Risk
Not
Functioning
Functioning-
at-Risk
Not
Functioning
Not
Functioning
POST-RESTORATION
VALUE
N/A
1.0
N/A
LWDI equals
LWDI of
reference reach.
Low BEHI Curve
Very low to
Moderate NBS
100ft
By year 5,
riparian
vegetation is on a
trajectory to
become similar
to the upstream
reference
condition.
CONDITION
RATING
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
3
Q.
x'
DO
>
T3
•g_
o'
Q}
rt-
o'
D
C/)
o
CD
D
QJ
03
r^-
CD
CO
IV)
-J
-------
TABLE BC2a CREDIT TEMPLATE 1: FUNCTIONAL LIFT DETERMINATION (CONT.)
a
5
CO
0)
(A
0)
3
i
o
3-
CD
CO
IV)
00
LEVELAND CATEGORY
2 - Hydraulics
4 - Physicochemical
5 — Biology
PARAMETER
Bed Form
Diversity
Water Quality
Nutrients
Benthic
Fish
Communities
MEASUREMENT
METHOD
Percent Riffle
and Pool
Depth Variability
(Pool Max Depth
Ratio)
Temperature
Dissolved
Oxygen
Nitrate-Nitrogen
Family- Level
Biological Index
(FBI)
McCormick
Index of
Biological
Integrity
PRE-RESTORATION(
VALUE
80:20
1.2
Project Reach is
not statistically
different than
reference.
Project Reach is
not statistically
different than
reference.
Not
representative
of reference
reach, but does
not cause
eutrophication.
5/8
50/75
CONDITION
RATING
Functioning-
at-Risk
Functioning-
at-Risk
Functioning
Functioning
Functioning-
At-Risk
Not
Functioning
in summer/
Functioning
in winter
Not
Functioning
in summer/
Functioning
in winter
POST-RESTORATION
VALUE
65:35
>2
Project Reach is
not statistically
different than
reference reach.
Project Reach is
not statistically
different than
reference reach.
Project reach is
representative of
reference reach.
8
75
CONDITION
RATING
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
3
Q.
x'
DO
>
T3
•g_
o'
Q}
rt-
o'
D
C/)
o
CD
D
QJ
03
r^-
CD
-------
Appendix B: Application Scenarios, Water Withdraw!
TABLE BC2b CREDIT TEMPLATE 2: PRE-AND POST-RESTORATION CONDITIONS
AND RATIONALE
Describe Pre- and Post-Restoration Condition and Rationale for Selecting Parameters
Hydrology - Performance standards are not provided from flow duration; however, the
summary report states that flow duration does not support species requirements in the
summer months. For these scenarios, the upstream reach or paired watershed can be
used to set a performance standard based on the reference condition.
Hydraulic - Floodplain connectivity is Functioning with a Bank Height Ratio of 1.2;
however, this is on the border between Functioning and Functioning-at-Risk. The post-
restoration condition is predicted to improve floodplain connectivity by decreasing the
ratio to 1.0. This may help improve groundwater/surface-water interactions and support
denitrification. Groundwater/surface-water interaction was selected even though there is
not a performance standard to acknowledge that these processes are key to improving
flow duration. Groundwater/surface-water interaction can be assessed directly with
shallow wells or tracers or indirectly assessed by measuring the results like the
Physicochemical and Biology parameters and measurement methods.
Geomorphology- Large woody debris has been removed from the channel and is Not
Functioning. Large woody debris will be added to the channel to create pools and
encourage bed aggradation. The prediction is that post-restoration condition will be
Functioning. There is a 10-foot buffer with cottonwood trees that will remain. The buffer
will be expanded to 100 feet to provide bank stability, cover, and treatment of agricultural
runoff. The existing bank erosion is on the outside of the meander bends, and since the
overall pattern is stable, bioengineering and wood structures will be used to improve
lateral stability to a Functioning level. Existing bed form diversity is Functioning-at-Risk
because pools are shallow and only located in the apex of bends. Large woody debris and
in-stream structures will be used to create a more complex bed form.
Physicochemical - Temperate and DO levels are used to measure water quality and are
both Functioning when water is present. These levels are supported by the existing
cottonwood trees, moderate bed form diversity, and health of the upstream watershed.
No change in the function score is predicted post-restoration, however these parameters
will be measurable for longer periods of time due to longer flow duration. Elevated levels
of nitrate-nitrogen enter the stream before restoration from adjacent cropland. Post-
restoration buffer and higher water table will support denitrification processes.
Biology- Macro in vertebrate and fish communities are Not Functioning in the summer
months when flow duration is below the level needed to support aquatic life. Post-
restoration, macroinvertebrate and fish communities will be Functioning year round.
A Function-Based Framework » May 2012 329
-------
TABLE BC2c CREDIT TEMPLATE 3: CREDIT CALCULATIONS
a
CO
0)
Vt
(0
Q.
0)
3
i
o
3-
CD
BEFORE FUNCTIONALITY
Low (Flow duration is Not
Functioning. Other key parameters
in Level 2-4 are Functioning-at-Risk
or Not Functioning). Key parameters
in Level 5 are Not Functioning)
Moderate (Flow duration is Not
Functioning. Other key parameters
in Level 2-4 are a mix of Functioning,
Functioning-at-Risk and Not
Functioning). Key parameters in
Level 5 are Functioning-at-Risk and
Not Functioning)
AFTER FUNCTIONALITY
Low (Flow duration is
Functioning-at-Risk.
Other key parameters
in Level 2-4 are
Functioning-at-Risk
or Not Functioning).
Key parameters in
Level 5 are Not
Functioning)
High (Flow duration is Not
Functioning. Other key parameters
in Level 2-4 are a mix of Functioning,
Functioning-at-Risk and Not
Functioning). Key parameters in
Level 5 are Functioning-at-Risk and
Not Functioning)
Moderate (Flow
duration is
Functioning. Other
key parameters in
Level 2-4 are
Functioning-at-Risk
or Not Functioning).
Key parameters in
Level 5 are Not
Functioning)
High (Flow duration
is Functioning. Other
key parameters in
Level 2-5 are
Functioning)
0.8
1.0
0.6
0.2
Category
Restoration
Enhancement
Preservation
(0
3
Q.
x'
DO
o
03
O
CD
D
03
^
o'
CO
03
r^-
CD
CO
CO
o
-------
Appendix B: Application Scenarios, Fish Passage
Restoration efforts have focused on dam removal and restoring salmonid habitat,
typically by adding large woody debris to the channels. These engineered log jams are
often used to raise the stream bed, stabilize streambanks, and to create sediment storage
areas upstream of the log jam while coarsening the bed downstream. The example below
includes the removal of a dam to create fish passage and the installation of LWD and
other natural structures to stabilize the bed and create salmonid habitat.
Example Scenario
A restoration site has been secured that includes a 10-foot high dam removal and
10,000 feet of degraded channel, 2,000 feet downstream of the dam and 8,000 feet
upstream. The stream is approximately 50 feet wide with a gravel/cobble bed. The
watershed is forested, but is managed for silviculture. The existing Bank Height Ratio is
1.5 downstream of the dam with moderate bank erosion and a coarse bed. The bed has
aggraded upstream of the dam, reducing the Bank Height Ratio to 1.2 and creating a finer
grain size distribution for the bed material. Streambank erosion is low. A forested buffer
extends the width of the valley throughout the full length of the project reach. Basic
water quality (pH, DO, conductivity and turbidity) meets the species requirements for
salmonids, which are plentiful downstream of the dam. These fish, however, are unable
to migrate past the dam due to its height. In addition, the bed material upstream is
unsuitable for salmonid habitat due to the aggradation of fine sediments.
The restoration approach includes the removal of the 10-foot high dam and the instal-
lation of engineered log jams and other structures to stabilize the stream bed. The struc-
tures will be installed throughout the project length to reduce Bank Height Ratios down-
stream of the dam and to spread out the elevation drop throughout the reach. The
structures will create a step-pool bed form, creating more resting areas for salmonids.
Fine grain sediments will still accumulate upstream of the structures leaving coarser
material downstream. However, the individual facet length of finer grained sediment will
be much less than above the dam. In addition, the wood will provide refuge for the fish
and habitat for aquatic insects.
The pre-restoration condition is a mix of Functioning, Functioning-at-Risk and Not
Functioning scores, with the downstream condition scoring lower for Hydraulic, Geo-
morphology and Biology functions. This equals a Before Functionality score of Moder-
ate. The post-restoration condition is predicted to be Functioning for all key parameters,
yielding an After Restoration score of High. A Moderate/High score provides a credit
ratio of 0.7. The total number of credits is 10,000 feet X 0.7 credit/ft = 7,000 credits.
A Function-Based Framework » May 2012 331
-------
TABLE BC3a CREDIT TEMPLATE 1: FUNCTIONAL LIFT DETERMINATION
a
CO
0)
Vt
(0
Q.
0)
3
i
o
3-
CD
CO
CO
LEVELAND CATEGORY
1 - Hydrology
2 - Hydraulics
3 - Geomorphology
PARAMETER
N/A
Floodplain
Connectivity
Flow Dynamics
Large Woody
Debris Storage
and Transport
Bank Migration/
Lateral Stability
Riparian
Vegetation
Bed Form
Diversity
MEASUREMENT
METHOD
N/A
Bank Height Ratio
Velocity
LWDI
BEHI/NBS
Average Buffer
Width (ft)
Buffer Density,
Composition,
Age, Growth and
Canopy Density
Depth Variability
(Pool Max Depth
Ratio)
PRE-RESTORATION CONDITION POST-RESTORATION
VALUE
1.5 (Downstream
of dam)
1.2 (Upstream of
dam)
Does not meet
species
requirements
LWDI does not
equal LWDI of
reference reach
Moderate
downstream of
dam
Low upstream of
dam
> 150
Similarto
reference reach
condition
1.2 (Downstream
of dam)
< 1.2 (Upstream
of dam)
RATING
N/A
Functioning-
at-Risk
Functioning
Not
Functioning
Not
Functioning
Functioning-
at-Risk
Functioning
Functioning
Functioning
Functioning-
at-Risk
Not
Functioning
VALUE
N/A
1.2
Meets
species
requirements
LWDI equals
LWDI of
reference
reach
Low
> 150
Similarto
reference
reach
condition
>2
RATING
N/A
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
3
Q.
x'
DO
o
0)
C/)
o
QJ
^
o'
co
CO
D-
-0
OJ
CO
CO
QJ
CQ
-------
TABLE BC3a CREDIT TEMPLATE 1: FUNCTIONAL LIFT DETERMINATION (CONT.)
a
CO
0)
Vt
(0
Q.
0)
3
(0
o
CD
LEVELAND CATEGORY
4 - Physicochemical
5 - Biology
PARAMETER
Basic
Water Quality
Benthic
M a c ro i n ve rte b rate
Communities
Fish Communities
MEASUREMENT
METHOD
Temperature
Dissolved
Oxygen
Conductivity, pH
Family-Level
Biological Index
(FBI)
McCormick Index
of Biological
Integrity
PRE-RESTORATION CONDITION POST-RESTORATION
VALUE
Project Reach is
not statistically
different than
reference.
Project Reach is
not statistically
different than
reference.
Project Reach is
not statistically
different than
reference.
5 (Downstream)
8 (Upstream)
70 (Downstream)
55 (Upstream)
RATING
Functioning
Functioning
Functioning
Functioning-
at-Risk
Not
Functioning
Functioning-
at-Risk
Not
Functioning
VALUE
Project Reach
is not
statistically
different than
reference
reach.
Project Reach
is not
statistically
different than
reference
reach.
Project Reach
is not
statistically
different than
reference
reach.
2
75
RATING
Functioning
Functioning
Functioning
Functioning
Functioning
3
Q.
x'
DO
o
C/)
o
CD
D
QJ
^
o'
CO
CO
CO
QJ
CO
CO
CO
CO
-------
Appendix B: Application Scenarios, Fish Passage
TABLE BC3b CREDIT TEMPLATE 2: PRE-AND POST-RESTORATION CONDITIONS
AND RATIONALE
Describe Pre- and Post-Restoration Condition and Rationale for Selecting Parameters
Hydrology - While silviculture can change the rainfall/runoff relationship, the watershed
hydrology in this example is stable. Hydrology parameters are used for the design, but
not as performance standards.
Hydraulic-A Bank Height Ratio of 1.5 indicates that the channel is moderately incised
downstream of the dam. This may be due to reduced sediment supply caused by the dam,
past changes to hydrology, past channelization, or a combination of impacts. The lower
Bank Height Ratio of 1.2 upstream of the dam is caused by sedimentation. Flow dynamics
was not described in the example scenario; however, the dam and channel incision will
increase channel velocities downstream of the dam. For this reason, velocity was added
as a measurement method. For this example, a performance standard was added based
on species requirements.
Geomorphology - Large woody debris has been removed from the channel and is therefore
Not Functioning before restoration. Engineered log jams will be the primary structure
used in the restoration and will create a Functioning score post-restoration. There is
moderate bank erosion downstream of the dam, which is primarily a result of channel
incision. This has created a Functioning-at-Risk pre-restoration score. The structures will
be used to reduce the bank heights and improve bank stability, improving the score to
Functioning. A mature forest exists throughout the project reach and is Functioning pre-
and post-restoration. Bed form diversity is measured by depth variability and shows a
Functioning-at-Risk pre-restoration score downstream of the dam. This is caused by a
reduction in sediment supply and channel incision. There are fewer riffles and pools
upstream of the dam due to sedimentation, resulting in a Not Functioning score.
Physicochemical - All water quality measurement methods are Functioning pre- and
post-restoration for this example due to the health of the upstream watershed and low
water retention from the dam.
Biology - The two methods of measurement shown are examples from Chapter 10 and
were developed for different regions. As methods are developed for the Northwest, they
should be added as a measurement method. If indexes are not available, a reference
reach approach could be used to compare the pre- and post-restoration condition to a
reference condition specifically for salmonids.
A Function-Based Framework » May 2012 334
-------
TABLE BC3c CREDIT TEMPLATE 3: CREDIT CALCULATIONS
a
CO
0)
Vt
(0
Q.
0)
3
(0
o
CD
BEFORE FUNCTIONALITY
Low (Dam is in place. Key
parameters in Level 2-4 are
Functioning-at-Risk or Not
Functioning). Key parameters in
Level 5 are Not Functioning)
Moderate (Dam is in place. Key
parameters in Level 2-4 are a mix of
Functioning, Functioning-at-Risk and
Not Functioning). Key parameters in
Level 5 are Functioning-at-Risk and
Not Functioning)
AFTER FUNCTIONALITY
Low (Dam is
removed. Key
parameters in Level
2-4 are Functioning-
at-Risk or Not
Functioning). Key
parameters in Level 5
are Not Functioning)
Moderate (Dam is
removed. Key
parameters in Level
2-4 are Functioning
or Functioning-at-
Risk. Key parameters
in Level 5 are
Functioning-at-Risk)
0.8
0.6
High (Dam is
removed. Key
parameters in Level
2-5 are Functioning)
1.0
0.7
Category
Restoration
Enhancement
3
Q.
x'
DO
o
0)
O
CD
D
QJ
^
o'
CO
CO
CO
CO
QJ
CO
CO
00
Ul
-------
Appendix B: Application Scenarios, Fish Passage
Scenario 4: Restoration of High Gradient, Headwater Streams
The restoration of high gradient, headwater streams is common in mountain regions of
the US, especially the Appalachian Mountains where restoration is often associated with
coal mining impacts. In addition, mountain headwater streams are often restored in the
East and the West to improve trout fishing. These streams are often found in v-shaped or
colluvial valleys and are often A or B stream types, and sometimes Cb stream types.
Energy is dissipated through vertical meandering rather than lateral meandering, which is
measured by sinuosity. In these higher-gradient streams, step-pool bed forms create
vertical meandering, which dissipates energy and creates the habitat needed for many
fish species, including trout. Therefore, restoration efforts focus more on bed form diver-
sity and more specifically measurement methods like pool-to-pool spacing and pool
depths than measures like sinuosity.
Example Scenario
A stream restoration project has been secured to restore 12,000 feet of mountain
headwater streams. The representative valley slope is 5% and the stream types are a B4.
The streams are located on an abandoned mine site. A uniform channel was sized to
carry the 25-year discharge and material from the mine site was used to line the chan-
nels. There are no trees along the riparian corridor other than a few small shrubs. Over
the years, the channels have further incised and bank erosion is prevalent throughout the
reaches. The streams are ephemeral to perennial; however, due to poor bed form diver-
sity and high flow energy, the stream does not support aquatic life in the perennial
reaches. The pH of the stream is a little lower than reference conditions.
The restoration approach is a watershed scale effort. The ephemeral, intermittent and
perennial streams are reconstructed based on natural channel design principles. The focus
of the restoration is to create a channel that only carries the bankfull discharge. All other
flows are transported onto a floodprone area, including the 25-year discharge. This is also
called a nested-channel approach. The pool-to-pool spacing and pool depths are designed
based on the slope of the channel, with steeper reaches having shorter pool spacing than
flatter reaches. A combination of boulders and wood are used to create the step-pool
structures. The channels are connected through a dendritic drainage pattern. Topsoil and
mulch are used to amend the soils in the riparian area and a 200-foot buffer of hardwood
trees and native shrubs is established.
This scenario fits the same credit determination method as the restoration of incised
channels. For this example, the pre-restoration condition included all Not Functioning
scores. Since this is a watershed scale approach, all of the post-restoration scores are
Functioning through Level 5. This results in a Maximum Lift with a credit range of
0.8 to 1.0. For this example, 0.9 credits are used. The total credits are 12,000 feet X 0.9
credits/ft = 10,800 credits.
A Function-Based Framework » May 2012 336
-------
TABLE BC4a CREDIT TEMPLATE 1: FUNCTIONAL LIFT DETERMINATION
a
CO
0)
(A
(0
Q.
0)
3
i
o
3-
CD
LEVELAND CATEGORY
1 - Hydrology
2 - Hydraulics
3 - Geomorphology
PARAMETER
N/A
Floodplain
Connectivity
Large Woody
Debris Storage
and Transport
Bank Migration/
Lateral Stability
Riparian
Vegetation
Bed Form
Diversity
N/A
Bank Height
Ratio
LWDI
BEHI/NBS
Average
Buffer Width
(ft)
Buffer
Density,
Composition,
Age, Growth
and Canopy
Density
Depth
Variability
(Pool Max
Depth Ratio)
PRE-RESTORATION CONDITION
VALUE
>2.0
LWDI does not
equal LWDI of
reference reach
High
0
None
< 1.2
RATING
N/A
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
Not
Functioning
POST-RESTORATION CONDITION
VALUE
N/A
1.0
LWDI equals LWDI
of reference reach
Low
> 150
Similar to
reference reach
condition
>2
RATING
N/A
Functioning
Functioning
Functioning
Functioning
Functioning
Functioning
3
Q.
x'
DO
o
(/)
o
03
5'
CO
O
Q)
5'
o
O
S
Q.
CT>'
D
r^-
C/)
rH-
cc
Q>
3
CO
CO
CO
-------
TABLE BC4a CREDIT TEMPLATE 1: FUNCTIONAL LIFT DETERMINATION (CONT.)
a
CO
0)
Vt
(0
Q.
0)
3
i
o
3-
CD
LEVELAND CATEGORY
4 - Physicochemical
5 - Biology
PARAMETER
Water Quality
Benthic
Macro! n vertebrate
Communities
Fish Communities
PH
WVSCI
Mid-Atlantic
Highlands IBI
PRE-RESTORATION CONDITION
VALUE
Slightly lower
than reference
condition
40
35
RATING
Functioning-
at-Risk
Not
Functioning
Not
Functioning
POST-RESTORATION CONDITION
VALUE
Project Reach is
not statistically
different than
reference reach
and support
species
requirements by
year 10.
70 by year 10
75 by year 10
RATING
Functioning
Functioning
Functioning
3
Q.
x'
DO
o
(/)
o
CT>
03
5'
CT>
W
O
Q)
5'
o
O
S
Q.
CD'
D
r^-
C/)
rH-
cc
Q>
3
CO
00
00
-------
Appendix B: Application Scenarios, Restoration of High Gradient Streams
TABLE BC4b CREDITTEMPLATE2: PRE-AND POST-RESTORATION CONDITIONS AND RATIONALE
Describe Pre- and Post-Restoration Condition and Rationale for Selecting Parameters
Hydrology - For this example, the Hydrology is stable enough to proceed with the project,
especially since the restoration is a watershed-scale effort. Restoration efforts will likely
reduce runoff and may increase flow duration. Therefore, there parameters could be
added as performance standards and evaluated against a reference condition.
Hydraulic - The Bank Height Ratio was not provided for the pre-restoration scenario;
however, the channel was designed to carry a 25-year discharge and would therefore be
severely incised. The new channel will be sized within the larger channel to carry the
bankfull discharge and the larger channel will be used as a floodprone area. This will
convert the Hydraulic functions from Not Functioning to Functioning. Groundwater/
surface-water exchange was not selected for this example, because the restoration
approach is a watershed-scale approach and there isn't a concern about the stream
classification, e.g., ephemeral or intermittent. If this was a concern, additional restoration
approaches could be used to change the groundwater/surface-water interaction. And in
reality, the addition of step-pools will likely improve flow through the hyporheic zone.
Geomorphology - The existing channel is devoid of LWD. Wood will be incorporated into
the step-pool channels so that the restored stream has an amount of wood that is
representative of reference streams. Pre-restoration bank erosion is high due to the
oversized channel and absence of vegetation. The change in channel dimension and the
establishment of a riparian buffer will reduce bank erosion to Functioning levels. The crux
of the restoration approach is the establishment of step-pool bed forms. These features
will provide vertical control and dissipate energy. They will also provide key habitat, along
with LWD, for native fish species.
Physicochemical - pH is Functioning-at-Risk due to past mining activities, the over-sized
channel, and lack of riparian vegetation. The combination of changes to channel
dimension (nested-channel), bed form diversity (LWD and step-pools), re-establishment
of the drainage network, and establishment of a riparian buffer will slowly improve water
quality. It is predicted to take 10 years before fully Functioning scores will be obtained.
Biology- Macro in vertebrate and fish communities are Not Functioning pre-restoration
due to all of the impacts to Level 2-4 functions. The restoration of these functions will
support the recruitment of aquatic insects and native fish. It is predicted that Functioning
levels will be achieved by year 10.
A Function-Based Framework » May 2012 339
-------
Appendix B: Application Scenarios, Restoration of High Gradient Streams
TABLE BC4c CREDIT TEMPLATE 3: CREDIT CALCULATIONS
CREDIT CATEGORIES PRE-RESTORATION CONDITION
POST-RESTORATION I CREDITS PER
CONDITION FOOT
Maximum Lift
Moderate Lift
Low Lift
All parameters in Pyramid
Levels 2 and 3 have Not
Functioning scores.
Parameters in Levels 4 and 5
are Not Functioning or
Functioning-at-Risk.
Mix of Not-Functioning and
Functioning-at-Risk scores for
parameter Levels 2 through 5.
Mix of Not-Functioning,
Functioning-at-Risk and
Functioning scores for
parameter Levels 2 through 5.
Functioning scores
for Levels 1-5.
Functioning scores
for Levels 1-5.
Functioning scores
for Levels 1-5.
0.8 to 1.0
0.6 to 0.8
0.4 to 0.6
A Function-Based Framework » May 2012
340
-------
-------
------- |