EPA-600/5-74-016
July 1974
AN ASSESSMENT METHODOLOGY FOR THE ENVIRONMENTAL
IMPACT OF WATER RESOURCE PROJECTS
By
Maurice L. Warner, John L. Moore, Samar Chatterjee,
David C. Cooper, Christopher Ifeadi, William T. Lawhon,
and Robert S. Reimers
Contract No. 68-01-1871
Program Element 1HA095
Roap/Task 21
Project Officer
Harold V. Kibby
Washington Environmental Research Center
Washington, D.C.
Prepared For
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. Environmental Protection Agency
Washington, D.C. 20460
For s»le by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $3.00
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FOREWORD
The wide spread use of environmental impact analysis as a means of
making Federal agencies decisions responsive to environmental concerns
was initiated by the passage of the National Environmental Policy Act
of 1969. The Act required that Federal agencies prepare statements
assessing the environmental impact of their major actions which sig-
nificantly affect the quality of the human environment. The Council
on Environmental Quality recently developed guidelines to define uni-
form procedures and approaches in the preparation of environmental
impact statements (EIS). While these guidelines specify what is de-
sired in Federal impact-statements, technical approaches to meeting
these objectives are not always available and universally acceptable.
Under Section 309 of the Clean Air Act, the U.S. Environmental
Protection Agency (EPA) is required to review, in writing, all EIS's
prepared by Federal agencies. Among the several obstacles to the
meaningful review of EIS's, has been the lack of consistency between
reviewers and the lack of standardized procedures for undertaking
reviews. The EPA Office of Federal Activities has undertaken the
task of writing a series of review guidelines for various classes
of EIS's.
As part of the Socioeconomic Environmental Studies, the Office of
Research and Development is conducting research to support both the
preparation and review of EIS's. Specifically, this research is de-
signed to:
Improve the ability of the Agency to
provide substantive technical review
of EIS's prepared by other agencies.
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Improve the technical quality of environ-
. mental impact analysis in areas of agency
responsibility.
Improve the effectiveness of the use of
environmental impact analysis in influ-
encing decision-making at all governmental
levels.
This report contains a review of the potential impacts associated
with the construction and operation of large water impoundments. It
was conducted by the Battelle Columbus Laboratories under contract from
the Washington Environmental Research Center, Office of Research and
Development, Environmental Protection Agency. The work was supported
by the Ecological Impact Analysis Staff.
Edwin B. Royce, Director
Ecological Impact Analysis Staff
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ABSTRACT
This report presents materials intended for use by reviewers
of environmental impact statements on major water reservoir projects.
The report is prepared as a series of six related but individually
referenced discussions of the following major topics:
• Reservoir project planning, construction, and
operation activities
• Water quality impacts of reservoir construction
• Ecological impacts of reservoir construction
• Economic, social, and aesthetic impacts of
reservoir construction
• Review criteria for assessing general statement
completeness and accuracy
• A review of impact assessment methodologies.
The materials presented attempt to call to the reviewer's
attention important issues or potential impacts that an adequate impact
statement should address. In addition, the water quality and ecological
impacts sections discuss the site-specific conditions under which a
given potential impact may or may not occur.
The section on water quality impacts also presents a detailed
comparison of mathematical models for predicting impacts on water tem-
perature, dissolved oxygen levels, and some chemical constituents of
surface waters. The sections dealing with water quality, ecological,
and economic-social-aesthetic impacts include extensive citations to
relevant literature the impact statement reviewer may wish to consult
for further information.
This report was submitted in fulfillment of Contract 68-01-1871,
by Battelle's Columbus Laboratories, under the partial sponsorship of
the Environmental Protection Agency. Work was completed as of May 1974.
IV
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TABLE OF CONTENTS
FOREWARD -jj
ABSTRACT iv
SECTION I. INTRODUCTION 1
SECTION II. WATER RESOURCE PROJECT ACTIVITIES 4
PLANNING 4
CONSTRUCTION 5
Land Acquisition 7
Relocation of Families 7
Power Line Construction 8
Flood Protection/Drainage Works Construction 8
Access Roads Construction 8
Canal Construction 9
Rock Blasting/Drilling 11
Demolition of Existing Structures 11
Soil/Debris Disposal 11
Quarrying and Stone Work 11
Concrete Batching/Placement 12
Embankment Construction 12
Dam Construction 13
Outlet Construction 14
Spillway Construction 15
Stream Bed Protection 15
Surface Finishing 15
Landscaping 16
OPERATION AND MAINTENANCE 16
Reservoir Filling 19
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TABLE OF CONTENTS
(Continued)
Page
Spillway Operation 19
Outlet Operation 20
Dredging 20
Foundation Drainage 20
Aeration . 20
Herbicide Treatment 21
Mechanical Plant Removal 21
Evaporation Control 21
Repairs of Defects, Leaks, and Weaknesses. . 21
•Function-Related Activities 22
REFERENCES 27
SECTION III. WATER QUALITY IMPACTS RESULTING FROM
RESERVOIR CONSTRUCTION 28
GENERAL CONTROLLING FACTORS 29
TEMPERATURE IMPACT AREA 32
Major Reservoir Influences on the
Temperature Impact Area 32
Techniques or Modes for Predicting
Temperature in Reservoirs 39
Temperature Prediction Downstream 50
DISSOLVED OXYGEN AND BOD IMPACT AREA 52
Major Reservoir Influences on Dissolved Oxygen ....... 52
Predicting Dissolved Oxygen (DO) in Reservoirs 58
DO and BOD Prediction in Streams and Estuaries 64
CHEMICAL IMPACT AREA 76
VI
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TABLE OF CONTENTS
(Continued)
Page
Major Reservoir Influence on Chemical
Constituents and Chemical Activity 76
Effects on Nutrients 77
Phosphorus Model 81
Effect of Toxic Compounds 82
Effect of Chemical Reactions 84
REFERENCES 85
SECTION IV. ECOLOGICAL IMPACTS. RESULTING FROM
RESERVOIR CONSTRUCTION 88
GENERAL ECOLOGICAL IMPACT AREAS 89
Terrestrial Impacts 89
Aquatic Impacts 93
TERRESTRIAL IMPACT ASSESSMENT CONSIDERATIONS 97
Inundation of Terrestrial Habitat 97
Changes in the Land/Water Interface 98
Creation of a Drawdown Habitat 101
Decreased Nutrient Inputs to the Downstream
Terrestrial Environment 103
AQUATIC IMPACT ASSESSMENT CONSIDERATIONS 103
Eutrophication 106
Sedimentation 115
Thermal Stratification 119
Dissolved Oxygen 122
Coliform Bacteria 124
Fisheries 126
vn
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TABLE OF CONTENTS
(Continued)
Page
MEASUREMENT CONSIDERATIONS 129
Terrestrial Ecology Measurement Considerations ,130
Aquatic Ecology Measurement Considerations . . 140
REFERENCES 143
SECTION V. ECONOMIC, SOCIAL, AND AESTHETIC IMPACTS
RESULTING FROM RESERVOIR CONSTRUCTION 151
A GENERAL FRAMEWORK FOR ANALYZING
SOCIOECONOMIC IMPACTS 151
Project Activities 152
Impact Classification 153
SOCIOECONOMIC IMPACT DESCRIPTION 157
Environmental and Economic Alterations
Planning and Construction Phases 158
Environmental and Economic Alterations
Operation Phase 161
Socioeconomic Effects 163
SUMMARY 173
REFERENCES 174
SECTION VI. REVIEW CRITERIA 177
GENERAL REVIEW CRITERIA 178
Completeness 178
ACCURACY 184
SECTION VII. A REVIEW OF ENVIRONMENTAL IMPACT
ASSESSMENT METHODOLOGIES 187
CHOOSING A METHODOLOGY 187
CATEGORIZING METHODOLOGIES 189
vi i i
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TABLE OF CONTENTS
(Continued)
Page
REVIEW CRITERIA 190
METHODOLOGY DESCRIPTIONS 195
ASSESSMENT METHODOLOGIES IN IMPACT STATEMENTS 211
Impact Identification 211
Impact Measurement 211
Impact Evaluation 212
Impact Communication 212
ENVIRONMENTAL IMPACT STATEMENTS REVIEWED 213
DEPARTMENT OF THE INTERIOR (DI), BUREAU OF RECLAMATION 213
DEPARTMENT OF THE ARMY (DA), ARMY CORPS OF ENGINEERS 214
TENNESSEE VALLEY AUTHORITY (TVA) 216
UNITED STATES DEPARTMENT OF AGRICULTURE (USDA),
SOIL CONSERVATION 218
FEDERAL POWER COMMISSION (FPC) 219
REFERENCES 220
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LIST OF FIGURES
FIGURE
Seasonal Variations in Temperature Gradients,
Lake Mead, Nevada • 37
Seasonal Salinity Distribution and Circulation
Patterns, Lake Mead, Nevada 38
Variations of k^ and ^2 With Temperature and
River Conditions 55
Idealized Representation of Oxygen Balance
Considerations for Various Physical Constraints 57
The Six Categories of Criteria To Be Applied To A
Structural Description of Vegetation Types... ' 136
Symbols for Structural Descriptions of
Vegetative Type , 137
Schematic Representation of Socioeconomic Impacts
of Reservoirs 155
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LIST OF TABLES
TABLE
L Water Properties As A Function Of Temperature 33
2 Selected Temperature Models 41
3 Selected DO Models For Reservoirs 59
4 DO Predictions In Stream and Euphotic
Zone of Reservoirs 67
5 Chemical Prediction Models 78
6 Potential Terrestrial Biological Impacts Associated
With Inundation Of Terrestrial Habitat 99
7 Potential Terrestrial Biological Impacts Associated
With A Change In The Land/Water Interface 102
8 Potential Terrestrial Biological Impacts Associated
With The Creation Of A Drawdown Habitat 104
9 Potential Terrestrial Biological Impacts Associated
With A Reduction Of Nutrients To The Downstream
Terrestrial Habitat 105
10 Potential Aquatic Biological Impacts Associated
With Reservoir Pool Formation 107
11 Potential Aquatic Biological Impacts Associated
With Alteration Of Downstream Flow Regimen 109
12 Relationship Between Trophic Status and
Primary Productivity Ill
13 General Environmental Impact Statement
Review Criteria 177
14 Summary Of Methodology Evaluations 194
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SECTION I
INTRODUCTION
This report presents a variety of technical materials intended
for use in reviewing environmental impact statements (E.I.S.) on major
reservoir construction projects. These materials are to assist the E.I.S.
reviewer in determining the completeness and accuracy of such statements
with special emphasis on water quality and ecological impacts. Since the
potential users of this material have a wide variety of backgrounds and
must deal with the full range of environmental conditions in the U.S. in
which reservoirs may be constructed, the materials in this report are
necessarily general in nature. Numerous citations to useful literature
on more specific project situations are provided.
Section II through VII of this report present interrelated
topics but are written to be useful as free-standing documents as well.
Each section contains a separate list of references (except Section II
and VI where no specific literature is cited). Each section is
summarized below.
Section II, "Reservoir Project Activities", presents brief
descriptions of the basic activities associated with planning, construction,
and operation of major reservoir projects. The major differences between
projects constructed to serve different purposes (e.g. flood control vs.
water supply vs. recreation, etc.) are also described. This section
serves as a general overview to give the E. I. S. reviewer a better grasp
of the full extent of project activities with possible environment impacts.
Section III, "Water Quality Impacts Resulting from Reservoir
Construction", presents a detailed technical discussion of predictive
techniques that are used to project possible water quality impacts of
reservoir construction. The impacts that are addressed include
the broad areas of water temperature impacts, dissolved oxygen
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impacts and impacts on chemical constituents of the water. The emphasis
in this section is on comparison of the various predictive techniques and
models presented to provide the reviewer with guidance on the
appropriateness of any particular technique in a specific project situation.
Section IV, "Ecological Impacts Resulting from Reservoir
Construction", provides the reviewer with information on the variety of
impacts a reservoir project may have upon terrestrial and aquatic
ecosystems. Since the magnitude, significance, and even the occurrence or
non-occurrence, of any single impact depends so highly on site-specific
conditions, this section is organized around general categories of
ecological impacts. For each category, emphasis is placed on specific
impacts experienced in the past as reported in the literature, and on
questions an EPA reviewer might ask to estimate the likelihood and magnitude
of an impact in a specific project situation. Additional attention is given
to the problem of impact measurement.
Section V, "Economic, Social, and Aesthetic Impacts Resulting From
Reservoir Construction", deals in a more general way with socio-economic
impacts and the relevant literature. The section identifies a variety of
impacts that may be produced by a project and gives citations to literature
dealing more fully with each impact. No attempt is made to define specific
techniques for quantitatively predicting economic, social, and aesthetic
impacts.
Section VI, "Review Criteria", presents a set of guidelines a
reviewer may use to assess the completeness and accuracy of an environmental
impact statement as a whole. In contrast to Sections III - V, Section VI
does not address any single area of potential environmental impacts.
Section VII, "A Review of Environmental Impact Assessment
Methodology", presents a summary and critical review of 17 frameworks or
tools for impact assessment. These 17 range from comprehensive "how to"
manuals for conduct of an assessment to single conceptual tools that have
been or may be applied to specific aspects of the impact assessment task.
It is hoped that this section will provide the EPA reviewer with some
perspective on the state-of-the-art in impact assessment.
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These various sectiont> are not organized into a step-by-step
E. I. S. review procedure or manual. It is expected that such a manual
will be prepared by EPA staff members, integrating information provided in
this report with the operating practices and statutory obligations of the
Environmental Protection Agency.
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SECTION II
WATER RESOURCE PROJECT ACTIVITIES
In order to identify and evaluate impacts associated with
reservoirs, it is first necessary to establish a general list and
description of project activities. Each water resource project con-
sists of several different types of activities having a variety of
environmental impacts. Major categories of activities are
(1) Planning
(2) Construction
(3) Operation (including maintenance and
project output).
Planning involves a whole gamut of activities that are under-
taken prior to ground-breaking and building of the project. Construction
involves those activities which create physical structures and actions
in accordance with the approved design. After the project has been
partially or completely built, it is operated in accordance with the
approved design specifications and operating procedures to produce the
specified project output. The maintenance of a water resource project
involves activities that are undertaken during the period of operation
to ensure that the safety, stability, and environmental desirability
of the system is maintained.
A "list" of specific activities within each general category
(planning, construction, and operation) is presented below. General
descriptions of the types of impacts associated with each category are
also provided in this section. Detailed discussions of water quality
and ecological impacts are presented in Sections III and IV of this
report, respectively. A less detailed discussion of socioeconomic
impacts is presented in Section V.
PLANNING
The planning process, per se, will not have any direct adverse
effects on the major focus of this research project; namely, ecological
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and water quality impacts. Planning activities such as those listed
below, however, can have very definite socioeconomic impacts.
• Public need assessment
• Reconnaissance
• Public hearings
• Design studies
• Project design.
Those socioeconomic impacts which occur at the planning stage
are due to anticipation of future reservoir related changes. For example,
conflict among opposing interest groups over the desirability of the
reservoir may result in deterioration of community cohesion. Speculation
in land adjacent to or below the proposed reservoir may be another impact
which occurs at the planning stage. Major opposition to the project by
those who would be displaced will also probably take place before land is
acquired and construction begun.
Since most of the socioeconomic impacts that occur at the
planning stage relate to anticipated environmental or economic alter-
ations, no explicit description of planning activities is considered
necessary. In reviewing impact statements, however, the analyst should
consider the extent to which anticipation of future changes may cause
explicit socioeconomic impacts which precede construction and operation
of the reservoir.
CONSTRUCTION
Construction involves those activities which create physical
structures and land alterations in accordance with the approved project
design. These activities are:
• Land acquisition
• Relocation of families
• Power line construction
• Flood protection/drainage works construction
• Access road construction
• Canal construction
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• Site/foundation preparation
• Rock blasting/drilling
• Demolition of existing structures
• Soil/debris disposal
• Quarrying and stone work
• Concrete batching/placement
• Enbankment construction
• Dam construction by various methods
• Outlet construction
• Spillway construction
• Stream bed protection
• Surface finishing
• Landscaping.
These activities cause a variety of physical/chemical, ecological,
aesthetic, and socioeconomic impacts of varying durations and degrees.
Physical/chemical changes occur during construction primarily as a result
of clearing and stripping of vegetative cover on the reservoir site.
This stripping process exposes soil to erosion thus increasing turbidity
in receiving waters. In most cases stream temperature is also raised.
The rate of basin runoff is also altered during the construction phase
due to vegetative removal. Ecological impacts include primarily the
destruction of supportive habitat for a variety of organisms. Clearing
of the site will remove forest and fields habitat resulting in the
displacement and outright destruction of terrestrial organisms. These
are, of course, long lasting or permanent changes in habitat subject
only to eventual dismantling of the reservoir and return of river flow
to a normal channel. Aquatic ecology would also be altered in the process
of reservoir construction. These alterations will relate to the turbidity
and erosion problems created during construction as well as the impacts
from increased water temperature, increased runoff rates, downstream
sedimentation, and physical removal of habitat due to straightening
and/or alignment of channels. Aesthetic impacts relate to the alter-
ation of the existing natural and man-made landscape and to the
introduction of various types of man-made structures. The appearance of
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existing landscape will be altered due to removal of trees, land
shaping, and temporary exposure of various types of soil at the
reservoir site. Various man-made objects will be introduced, including
various forms of access roads, power lines, the dam structure itself, and
any related support facilities. Amenity factors, such as odor and noise,
may also be affected during reservoir construction. Socioeconomic
impacts during the construction phase relate primarily to the effects
on persons displaced from the reservoir site; to the disruption and
blocking of various public utilities, roads, and other infrastructure
important to adjacent communities; to removal of land from its present
use; to distruction or removal of cemeteries, historical buildings and
sites or unique natural resources or attributes of the site, and to
destruction of recreation areas associated with free flowing streams.
These construction related alterations will have particular effects on
community cohesion and social activity patterns.
Definitions and descriptions of the general activities that
can cause the above types of impacts are presented below.
Land Acquisition
Water resources projects involving reservoirs, canals, etc.,
involve large tracts of land that must be acquired for physical project
use. Creation of a reservoir across a natural channel can flood a
large tract of land upstream. Construction of canals requires
land for its right-of-way. These lands may be acquired by fee
simple title, by condemnation, easement, etc.
Relocation of Families
Before actual construction of structures can begin on a water
resource project, the people living on the acquired land must be re-
located elsewhere, possibly on nearby land. This important issue has
frequently been a major cause of opposition to water resource projects.
The current opposition and distrust of government action in regard to
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relocation of families is based on precedent. As Morgan (1971) points
out, there has been a pattern of improper and unjust handling of dis-
placed families, especially the Indian population.
Power Line Construction
The large majority of water resource projects consume con-
siderable amounts of energy during construction and during operation.
Therefore, a power line must be constructed from a major source of power
to the site. Generally towers are used to carry high tension lines
across country long distances to the construction and operation site.
Flood Protection/Drainage Works Construction
Construction of dams generally involves creation of temporary
flood protection and drainage works that will protect the dams and
embankments against high floods during construction. These protection
works can have different configurations. They may involve construction
of a coffer-dam which prevents flood water from entering the construction
site, or construction of a diversion tunnel that diverts the flood waters
away from the construction site, thus preventing flood damage to the
incomplete structures.
Access Roads Construction
Frequently, water resource projects including dams and reservoirs
are built in natural areas that are not accessible by land transportation.
In the first phase of construction, temporary roads are built that provide
access to various critical locations of the project where men and materials
must be deployed to construct and operate the project. These temporary
access roads are generally unpaved.
On completion of the project, some of these roads, which are
needed during operation and maintenance, are paved and turned into
permanent roads. Many other stretches of the access roads not needed
during project operation and maintenance are abandoned, occasionally
resulting in significant soil or slope erosion problems.
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Canal Construction
Construction of canals involves major operations of digging
and filling over a large area. Canals are used to carry water from the
reservoir to distant arable land which is unproductive or less pro-
ductive due to the scarcity or shortage of water. Generally, canals
are artificial channels cut to transport irrigation watar.
Site/foundation Preparation -
Preparation of the foundation is an essential feature in the
proper design of dams and reservoirs. The foundations must be designed
to restrict excessive foundation pressures, to provide necessary sliding
resistence, and to maintain flexibility without loss of structural
strength. The foundation on which reservoirs are built are of five
general types: rock, pervious soil, impervious soil over rock,
impervious soil over pervious soil, and stratified soil. Different
types of foundations require different kinds of preparation or treatment
for construction and maintenance safety.
Site Clearance -
A natural reservoir site generally has extensive vegetation,
trees, soft uncompacted soil, and other features not suitable as a
stable foundation for a reservoir. Site clearance involves removing
or clearing all vegetation on top of the soil. In this activity only
the vegetation on top of the soil is removed.
Grubbing -
Grubbing is a specific operation which begins after site
clearance and involves removal of tree stumps and roots.
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Stripping of Top Soil
Generally the top soil has a weaker texture than subsoil.
It has a high degree of organic content and is therefore subject to
a high degree of settlement. Also, it may be impervious or subject
to swelling as a result of exposure to water. It is, therefore,
essential to remove the top soil in the area on which a reservoir
foundation is built. Generally, the ground below the top soil is
well compacted and is suitable for construction of reservoir structures.
Cutoff Trenching -
Generally, the foundations are pervious or only partially
impervious due to the inherent characteristics of the underlying soil.
It is therefore advisable to extend an impervious trench sufficiently
deep into the foundation to insure that no seepage of water occurs
)
thro'ugh the foundation. As such, a trench is generally dug at the
center line or on the upstream end of the foundation and is carefully
filled with compacted impervious embankment material.
Grouting -
Grouting is generally done in rock foundations. It is
intended to prevent leakage. It reduces uplift under the dam; and it
consolidates seamy broken foundations making them stronger.
Cement grout usually consists of a mixture of one part cement
and five to six parts water. First, a series of holes are drilled at
frequent intervals in the foundation of the dam. The grout is then
pumped under pressure into these holes. The thin grout usually reaches
remoter seams and causes minimal disturbance to the natural formation.
After sufficient thin grout has been pumped, a mixture of one part
cement to two parts water, which is a thick grout, is pumped to insure
proper sealing of the foundation. Where there is difficulty in sealing
a seam, it is necessary to use sawdust or wood shavings along with the
cement-water mixture. Hot asphalt grout has also been used to seal
cavities containing running water.
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Special Compaction Treatment - ;
There are several different methods of foundation compaction
currently available for use. Some of these methods are: explosive
compaction, vibroflotation and chemical/electrical treatment. These
methods are generally used to consolidate and improve the character-
istics of the foundation soil.
Rock Blasting/Drilling
On dam sites or reservoir sites that have a rocky foundation
or canyon, certain operations will require blasting and drilling through
the rocks. Construction of a tunnel through the canyon, or construction
or a surface channel under rock surface will require rock blasting and/or
drilling at the reservoir site.
Demolition of Existing Structures
Creation of reservoirs require the removal of all existing
structures within the reservoir area.
Soil/Debris Disposal
Construction activities at a reservoir project generate
large quantities of soil and debris that must be disposed of in an
environmentally sound manner. A major factor of the environmental
effects of reservoir projects is the availability and capacity of
suitable disposal sites.
Quarrying and Stone Work
Construction of masonry dams requires large quantites of
stones and rock aggregates, obtained from quarries.
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Concrete Batching/Placement
A concrete batching plant is a mechanized system for producing
concrete of a given strength and consistency to be transported to the
site to construct structures supporting the dam. The batching plant
takes measured quantities of rocks and mixes them with suitable amounts
of sand and cement and water to produce the concrete needed to build
masonry structures. The concrete is then transported by a suitable
conveyor system to the forrawork to cast concrete masonry structures.
The concrete is placed in several layers and finally dried and cured.
Embankment Construction
Embankments are earth filled or rock filled structures that
are built by piling up large quantities of soil or rock over a large
wide base to a reasonably high depth. Earth embankments are generally
wider at the base and shorter in height compared to masonry dams.
Excavation -
Large volumes of soil are needed in the construction of earth
embankments. This soil is obtained by excavation of suitable borrow
pits near a reservoir site.
Placing of Soil/Rocks/Gravel -
The excavated soil is transported by dump trucks and tipped
off at suitable locations at the fill site. Also, the excavated material
may be directly taken from the borrow pit and deposited at the filling
site.
Compaction -
After the soil is placed on the base of the fill, it is com-
pacted by various methods. One type of compaction is rolled fill, which
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is produced by using sheep-foot or wobbly-wheel rollers to compact
each layer of soil placed on the base of the embankment. Another
type of embankment is made of hydraulic fills. In this case, the soil
is hydraulically transported to the base of the embankment and allowed
to settle and compact under a sufficient head of water.
Slope Protection -
Slope protection is an important feature of earth dams,
embankments, and canals. One way of protecting slopes is to dump rip
rap on the slopes, especially in zones where the embankment would be
substantially affected by wave action of wind driven waters. Another.
method of slope protection is the stabilization of slopes by sodding.
Still another way of protecting slopes is to provide concrete facings
along the slopes vulnerable to erosion.
Dam Construction
Several alternative means of dam construction have been used,
incorporating steel, masonry, concrete, and lumber in addition to the
previously discussed earthen embankments. Special features of these
various types of construction are described below.
Masonry Construction -
*
Masonry dams are of the following different types: capital
gravity, single arch, multiple arch, arch-gravity, and buttress. Here
the masonry dams have been assumed to be only those dams which use all
possible types of masonry other than concrete. Construction of these
structures involve transporation and placement of masonry.
Concrete Construction -
Concrete dams are of many different types, including gravity,
single arch, multiple arch, arch-gravity, and buttress dams. Basically,
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the concrete construction consists of preparation of formwork or
shuttering, installation of steel reinforcements, transporation and
placement of concrete in layers within shutterings, and drying and
curing of the concrete.
Steel Construction -
Many dams have certain steel components built into them. For
example, steel cranes are installed on many dams; gates and regulators
are often made of steel structure; in addition, there can be many other
steel structures for limited operational purposes.
In the past some steel dams have been built. However, they
have been subjected to serious corrosion problems. Also, it is no longer
economical to build steel dams in most instances. No steel dams are
known to have been built in the past 30 years.
Lumber Construction -
Generally, dams do not have any lumber built into them.
In earlier times there were some lumber dams built for storing water.
These dams have proved satisfactory from the standpoint of longevity
and cost of construction.
Outlet Construction
Adequate outlets must be provided in the dams to permit the
water to be released for different purposes. Undersluices are used to
discharge water at high head during periods of flood when the spillway
runs at full capacity. Also, undersluices may be used at times when
the water level is below the spillway level and downstream releases
are needed. At times, intake wells are built behind the dams within
the reservoir to withdraw water for purposes of water supply. Certain
modern dams have fuse plugs built into the embankment. Fuse plugs may
be exploded during high flood water level to discharge the water behind
the dams and thus save the dam from being overtopped and destroyed by the
flood waters.
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Spillway Construction
Spillways are a form of overflow outlets, built into a dam,
to be used during floods when the reservoir is filled above the highest
storage level. Some spillways have adjustable gates at the top to
regulate the flow. Generally, a spillway is designed to handle a flood
with a frequency of 1,000 years. However, when actual flood flows
exceed that limit, the dam is overtopped. Other outlets may be used
to prevent tlie dam from being overtopped. If the dam is a flood control
structure, it is essential that it be designed to withstand any amount
of overtopping. This is very important since the failure of a flood
control dam during high flood period could cause massive damage to
communities downstream.
Stream Bed Protection
The release of water from the reservoir through the under-
sluice or over the spillway generates tremendous amounts of power to
erode the stream bed. Excessive erosion at the toe of the dam could
endanger stability and hence the safety of the structure. The hydraulic
jump, quickly reducing the velocity of water, is usually the most
effective way of preventing erosion. Baffles or sills may also be used
to dissipate energy downstream of the jump. The energy can also be
dissipated on the apron by placing a sloping floor and chute blocks in
the stilling pool formed on the apron.
Surface Finishing
Dams are large structures built across rivers and canyons.
It is necessary that visible portions of the dam be aesthetically pleasing.
The surfaces of the dam need therefore to be properly finished. The con-
crete dams are finely finished and the surface is suitably plastered to
look pleasing in the daytime as well as at night. The earth dams
are seeded with grass and maintained properly in order to be
aesthetically pleasing and to prevent erosion as a result of rain,
wind, and snow.
15
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Landscaping
Development of a suitable aesthetically pleasing landscape at
and around a reservoir site is an important feature of water resources
projects. This can be achieved by seeding all man-made fills, excavated
and quarried sites, and also slopes eroded by natural forces. Intell-
igent planning of borrow pits and fill sites can create excellent
physical arrangements for aesthetically pleasing landscapes around
reservoir sites.
OPERATION AND MAINTENANCE
After the project has been partially or completely built, it
should be operated in accordance with the approved design specifications
and operating procedures to produce the specified project output. Main-
tenance activities must also be undertaken to ensure that the safety,
stability, and environmental desirability of the project is maintained.
Operation activities and output characteristics will have a
variety of impacts. Some impacts will be general to all large reservoirs.
Others will depend on how the specific project purpose modifies reservoir
operations, primarily timing, duration, and magnitude of water releases
and reservoir water levels. General reservoir operation and maintenance
activities include:
• Reservoir filling
• Spillway operation
• Outlet operation
• Dredging
• Foundation drainage
• Aeration
• Herbicide treatment
• Mechanical plant removal
• Evaporation control
• Repairs of defects, leaks, and weaknesses
16
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• Function-related activities associated with reservoirs including:
- recreation
- power generation
- flood control
- domestic water supply
- agricultural water supply
- multipurpose projects.-''
Reservoir operation and maintenance activities can cause a
variety of water quality, ecological, aesthetic, and socioeconomic
impacts of varying durations and degrees. Water quality impacts
result primarily from the alteration of a free-flowing stream to a
standing body of water. Water quality impacts can be associated
with two different phases of reservoir operation. The first is the
transition phase involving filling of the reservoir and the first several
years of operation. The second phase involves the water quality
characteristics of the reservoir after transitional types of water quality
impacts have subsided.
In the first phase, decomposition of any remaining organic
material on the project site will alter the incoming stream water
quality, due to biological oxygen demand and enrichment of the water
in the decomposition process. Floating material and the initial tur-
bidity level also may be higher during this first phase than that of
the incoming waters. These general water quality alterations will
be reflected to a certain extent in the outflow of the reservoir and in
downstream water quality.
The most important water quality changes, however, are
related to the effect of impounding free-flowing water. One of the
primary factors here is the degree to which impoundment results in
thermal stratification of the reservoir. Thermal stratification will
create a warmer layer of water overlying a lower colder strata during
warm weather. The opposite pattern generally holds during the winter.
* Most large reservoirs will involve multiple purposes and this is probably
the most typical situation that the impact statement reviewer will face.
17
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The effect of this stratification is most pronounced in the summer when
the colder bottom layers tend to be void of oxygen. Major implications
of this relationship are complex and are discussed in detail in Section
III of this report. In general, release of oxygen-deficient cold waters
from the bottom layers of the reservoir in summer will alter downstream
preproject water quality characteristics just as release of warmer
waters from the surface layers of the reservoir will alter the preproject
downstream water quality.
Other water quality impacts that may result from operation
include an increase in clarity as fine sediments settle out of the
standing water, alterations in downstream flow regime due to timing and
frequency of releases from the reservoir, and water level fluctuations
within the reservoir itself.
Ecological impacts due to operation will relate to the above
physical/chemical changes. Fundamental among these will be downstream
water level fluctuations at critical periods in the life cycle of aquatic
organisms and similar water level fluctuations within the reservoir itself.
Downstream changes in physical/chemical water quality may also alter the
nature of the aquatic ecosystem. In this case temperature is a primary
factor of concern. Problems of oxygen-deficient water or water that is
super saturated with nitrogen also play an important role in downstream
ecosystems as does the physical blocking of the stream for migration
for certain species of fish. Impacts on terrestrial ecology from
operation of the reservoir will be very site-specific but relate
primarily to elimination of terrestrial habitats due to flooding and to
the interface of the terrestrial ecosystem with the ecosystem in the
stream reach below the reservoir.
Most aesthetic impacts associated with reservoir operation will
be related to the amenity conditions such as noise and odor problems.
Odor may occur under certain conditions of algal growth or anaerobic phases
of decomposition. Noise will relate to secondary developments around the ,
reservoir and traffic generation caused by socioeconomic changes.
Socioeconomic impacts are a direct function of the reservoir
purpose, its size, and its proximity to urban populations. The most
18
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significant consideration from an operational point of view is the
extent to which project operational characteristics induce various
secondary developments. Important among these are second home
development, recreational use, and industrial location due to increased
water and power supplies. These developments, along with those associated
with the specific project purpose (for example, irrigation) can be
expected to change regional income and income distribution, create new
demands for public services and new sources of public revenue, and
cause changes in existing social activity patterns and life styles.
Specific operations and maintenance activities are defined
and described below.
Reservoir Filling
The first filling of the reservoir is an important event in
the life of the project. Many difficult environmental and safety problems
may rise during filling. It takes about 5 years before the new reservoir
environment approaches stability. The first filling of the reservoir
should be carefully and cautiously handled and monitored. Also, during
the first 5 years, the reservoir filling operation should be given
substantial attention to determine the types of erosion problems that
might develop, and potential seepage, leakage, and piping problems that
are likely to develop in the dam or along the natural reservoir embank-
ment. The transportation of silt from upstream disturbed areas into the
reservoir should also be monitored and abated.
Spillway Operation
The operating procedures of the spillway are an important
aspect of the reservoir environment. They determine the highest
water level upstream of the spillway as well as the fluctuation of
water downstream.
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Outlet Operation
The outlet operation greatly depends on the purpose for which
the reservoir has been built. Uniform releases are generally made from
a water supply reservoir. Periodic releases are made from power dams as
well as agricultural reservoirs. The flow rate varies daily in the case
of power reservoirs, whereas in the case of agricultural reservoirs it
may vary seasonally.
Dredging
The dredging of reservoirs, channels, and canals is an important
activity in many water resources projects. A reservoir that is being rapidly
silted up must be dredged to prevent its losing effective storage capacity.
Channels for navigation must be dredged regularly to increase the effective-
ness of their use. Channelization is done in sluggish streams to
enhance the rate of flow, thereby preventing flood damage in the vicinity
of the stream. Also, silt transported with irrigation water from the
reservoir can fill up deep irrigation canals unless periodically dredged.
Foundation Drainage
Foundation drainage is an important feature of a water resource
project. Creation of reservoirs and canals as components of many water
resource projects results in water logging due to the lack of proper
drainage in areas that have impervious or semi-impervious soils. Water
logging may create many serious problems, including breeding of mosquitoes,
flies, and other insects and disease microorganisms. Suitable drainage
will therefore be designed in the dam foundation as well as in the
vicinity of reservoirs and canals where water logging is likely to occur.
Aeration
Reservoirs are aerated to prevent dissolved oxygen deficiency
problems that may result from reservoir stratification.
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Herbicide Treatment
Many different kinds of undesirable vegetation can grow on the
sides and shallow bottoms of reservoirs. The growth of these undesirable
organisms can be controlled by using specific types of herbicides. How-
ever, the use of herbicides in an excess amount can cause serious chemical
pollution of water, thereby endangering aquatic organisms and water quality.
Mechanical Plant Removal
The growth of plants in the reservoirs can create serious water
quality problems as well as reduce the capacity of reservoirs. Therefore,
to maintain sufficient capacity within these reservoirs it may be necessary
to use mechanical devices for plant removal from the reservoir bottom.
Evaporation Control
In warm arid regions, the reservoir is subjected to a high rate
of evaporation loss from its surface. Also, certain categories of plants
cause serious evapotranspiration losses from reservoirs. Such evaporation
and evapotranspiration losses can be abated by various methods. Certain
organic films or monolayers of cetyl alcohol, stearyl alcohol, etc., can
be sprayed over the water surface to prevent excessive evaporation. Also,
the use of certain chemicals to poison these highly transpiring plants
around a reservoir can effectively abate high evapotranspiration losses
from reservoirs.
Repairs of Defects, Leaks, and Weaknesses
Dams and reservoirs are always subjected to significant stress
caused by natural changes in the environment. These stresses may cause
major defects in the structure of the reservoir. They may lead to serious
leaks and weaknesses in the structure of dams and embankments. These de-
ficiences can have serious implications for the aquatic environment. Timely
repairs are needed to guard against potential damages to the environment.
21
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Function-Related Activities
The magnitude, frequency, and duration of operational impacts
will often be related to the purpose of a specific reservoir project.
While reservoirs are usually designed for multipurpose outputs, des-
cription of individual functions and their relation to operational impacts
can be useful in understanding the impact generation process. Each of
several individual functions is discussed briefly below.
Recreation -
Permanent recreation facilities and stable recreation use of a
reservoir requires the maintenance of a minimum elevation pool during
the recreation season. This requirement, if dominant, will tend to
regularize flows during the recreation season. Depending on the level
of the reservoir at the end of the winter, high spring flows will
normally be withheld, reducing downstream flow. Again, depending on
the rules governing downstream releases and pool elevation during
the recreation season, excess runoff will probably be withheld. This
will further regularize downstream flows. The ecological impact of
regularization relates to the life cycle of various aquatic species,
particularly those that require high spring flows for access to spawning
areas. Other impacts associated with recreation reservoirs relate to
recreation use and recreation facilities and second home development.
Heavy recreation use (power boats in particular) will create water quality
problems. Extensive recreational development may create water quality
problems if septic tanks or sewage facilities are inadequate. Traffic
congestion may also be a problem during periods of peak use.
Power Generation -
Falling water is a resource for generating electricity. A
run-of-river plant uses only unregulated river discharges and is practical
only on streams with appreciable dry-weather flow. A pondage plant, on
22
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the other hand, retains the night-time discharges for use during the peak
hour power demand of the next day. Still another category is the seasonal
storage plant that retains the wet-season flood flows for use during the
subsequent dry periods. The cyclic storage plant has the capacity to
store water lasting several years during extended dry periods.
Another facet of power production is pumped storage. A pumped
storage development is a reservoir facility intended for peak-load power
generation. In the United States and many other industrialized countries,
the operations of nuclear power stations with high output ratings have
frequently been tied to large pumped-storage facilities. Also, there
has been a tendency to develop storage power stations of an economic
combination of large dams and pump-storage operations. This arrange-
ment very effectively increases the firm peaking power capacity of a
generating system. However, pumped-storage systems without natural
inflow continue to be predominant at this time. In principle, the
pump-storage facility permits the operation of major power stations at
a rating higher than the off-peak demand. The excess energy generated
during off-peak hours is used to pump water to an upper reservoir for
storage. During the peak hours, the pumped-storage reservoir releases
the off-peak stored water to generate additional power needed above the
output rating of the power station.
A hydroelectric power project stores water in a reservoir and
allows it to pass through trashracks, penstocks, and then through the
turbines. The energy of the falling water is thus converted into
rotating shaft energy, which in turn is transformed into electrical
energy by generators. Downstream of the power plant there is generally
an afterbay to even out the discharge pattern of evening peaks and early
morning low flows. The general effect on flow is to cause increased
fluctuations, either on a daily basis in the case of peaking facilities,
or to increase fluctuation seasonally in the case of base load facilities.
Increased water level fluctuations, either daily or seasonally,
have major implications for downstream and reservoir aquatic ecology.
These are described in detail in Section IV of. this report. In general,
change in natural patterns of downstream water level fluctuation can be
in conflict with the spawning, nursery, and feeding requirements of
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various fish species. Similar conflicts will also limit the productivity
of the reservoir itself, if water level fluctuations are significant at
critical times of the year. Other specific impacts that can be linked
to power projects include aesthetic effects such as conspicuous "bath
tub rings" (the draw down zone), power transmission lines, and potential
industrial development or expansion.
Flood Control -
A flood control reservoir has the capacity of containing high
flood flows up to a given maximum discharge. The retarding structures
and reservoirs store peak flows in order to reduce flood damage down-
stream. In addition, channel improvements may be made to enhance the
flood carrying capacity of rivers. Also, levees keep the water away
from developed areas. The floodways and bypasses divert flood flows
from the main stream around developed areas of a city and prevent
flood damage. The major influence of flood control projects is to
create a more regular flow during most of the year, which will have
environmental impacts similar to those discussed for recreation reservoirs,
A single purpose flood control reservoir will be operated differently,
however. Extensive capacity will generally be maintained to accommodate
sudden, large discharges. In the extreme, this operational feature
will result in an unstable aquatic habitat in the reservoir itself.
Regularization of downstream flows may or may not be beneficial to
the aquatic habitat, depending on pre-project conditions.
Other types of impacts relate to the downstream land develop-
ment incentives created by flood protection. Urban encroachment on
the flood plain following construction of the reservoir will result in
terrestrial habitat losses over and beyond those caused by the reservoir
itself and may lead to catastrophic losses from a truly major flood.
Domestic Water Supply -
Water supply projects are intended to supply adequate quantity
and quality of water for municipal, commercial, and industrial operations.
24
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Operationally, water supply reservoirs tend to regularize flow since
the project is designed to provide a steady output of potable water.
The effects of regularization would be similar to those described for
recreation reservoirs. For a single purpose domestic water supply pro-
ject, however, pollution would be less of a problem due to the absence
of recreational use.
Agricultural Water Supply -
Single purpose irrigation projects involve storage and trans-
mission of water to extend the area of arable land or to improve the
productivity of existing cultivated land. Basically, these projects
consist of reservoirs that store off-season flows for use during the
irrigation season, and a system of canals that transport water to lands
that need water for agriculture. Irrigation projects tend to smooth
water flow, storing high flows in the spring and releasing them during
dry summer months. Water levels in the reservoir will tend to have a
wider variability than those in single purpose domestic water supply
or recreation reservoirs. This is due to the seasonal drawdown for
crop water consumption requirements. Seasonal variation in water
levels may result in lower than maximum potential productivity for
the reservoir. Regularization of downstream flows may have either a
beneficial or adverse effect on aquatic ecology.
The irrigation water, after passing through permeable soils,
is capable of returning to the same river at some point downstream.
The chlorides, nitrates, and other salts present in the soil may be
dissolved by the irrigation water as it passes through these soils.
At the point where these agricultural flows return to the river they
may have a high degree of salinity. As such, the irrigation return
flows can be the cause of serious water quality problems in many areas.
Also, the operation of canals can have major impacts on the environment
of a given region. Excessive water logging can create serious insect
and bacterial damage to nearby areas.
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Multipurpose Projects -
Most major water resource projects are built with multiple
purposes in mind. For instance, a reservoir may be built to control
floods during flood season, as well as provide water supply during
most parts of the year. It may be used for irrigation as well as
power generation and waste water dilution. In addition, most large
reservoir projects built today include provisions for recreation. The
impacts associated with multipurpose reservoirs cover the spectrum
of general impacts discussed previously as well as those that are
specific to the dominant reservoir function. Detailed discussion of
these impacts is the subject of the next two sections of this report.
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REFERENCES
Armstrong, E. L. 1973. Dam construction and the environment. Transactions,
Internat'l Congress on Large Dams, Rept. No. 16, Q. 40, Madrid, pp 221-240.
Cheret, I. 1973. The consequences on the environment of building dams.
Transactions, Internat'l Congress on Large Dams, General Rept., Q. 40,
Madrid, pp 1-103.
Cortright, O.C.J. 1970. Re-evaluation and reconstruction of California
dams. J. of the Power Division, ASCE, Vol. 96, No. P01, pp 55-72.
Davis, C. V. 1952. Handbook of applied hydraulics. McGraw-Hill Book
Co., New York, p 1249.
Dickerson, L. H. 1970. Supervision of dams and reservoirs in operation.
Tenth Internat'l Congress on Large Dams, General Rept., Q. 38, Montreal,
PP 223-279.
Elliott, R. A. 1973. Consequences on the environment of the TVA reservoirs
system. Transactions, Internat'l Congress on Large Dams, Rept. No. 15,
Madrid, pp 191-215.
Justin, Hinds, and Creager. 1945. Engineering for dams. John Wiley &
Sons, Inc., New York, Vol. Ill, pp 660-661.
Kuiper, E. 1965. Water resources development: planning, engineering,
and economics. Butterworths, Inc., Washington, D.C., pp 210-263.
Mermel. T. W. 1970. Summary of dam construction activities during three-
year period 1966-1969. ICOLD Committee Rept. Bureau of Reclamation,
Washington, D.C., p 3.
Middlebrooks, T. A. 1953. Earth dam practice in the United States.
Transactions, ASCE, Centennial Vol., pp 697-722.
Morgan, A. E. 1971. Dams and other disasters. Porter Sargent Publ.,
Boston, Mass., p 63.
Sherard, J. L., R. J. Woodward, S. F. Gizienski, and W. A. Clevenger.
1963. Earth and earth-rock dams. John Wiley & Sons, Inc., New York,
pp 113-199.
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SECTION III
WATER QUALITY IMPACTS RESULTING FROM RESERVOIR CONSTRUCTION
INTRODUCTION
The most fundamental changes produced by reservoir construction
include changes in physical and chemical characteristics of the water itself.
These water quality changes, in turn, trigger further changes in the
ecology, aesthetic quality, and ultimately in the human use of the reservoir
region.
The major water quality impacts of reservoir construction can be
grouped into three main areas: temperature impacts, dissolved oxygen
impacts, and impacts on chemical constituents of the water. Of these three
areas, temperature impacts are the most pervasive with other changes driven
by or closely linked to temperature. The level of biological activity, for
example, (as measured by gross productivity) doubles for every 10 degree
Centigrade increase in water temperature, creating a corresponding
increase in oxygen demand. Dissolved oxygen solubility decreases when
temperature increases.
The activity and fate of chemical constituents such as nutrients
and toxic chemicals such as pesticides are also closely interwoven into this
web of interactions. The reservoir itself acts as a nutrient and chemical
trap, incorporating chemical constituents into the bottom sediments in
stabilized forms. When the reservoir becomes thermally stratified, however,
these chemical constituents may be released from the sediments due to
anaerobic decomposition. Thus, water quality downstream from the
reservoir may fluctuate widely with time ; from the free flowing stream
condition to a state of chemical impoverishment to chemical enrichment.
The above examples illustrate the important and complex interactions
that occur between water quality characteristics and between water quality
and other aspects of the reservoir system. In some cases, these interactions
are sufficiently well understood to permit the prediction of water quality
characteristics anticipated after reservoir construction via mathematical
formulae or-simulation models. This section reviews the most important of
28
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the analytical models for predicting water temperature, dissolved
oxygen, and chemical constituents. In each case, major reservoir influences
on the impact area are described, then tools for predicting in-reservoir
conditions are described and compared, and finally, downstream impacts in
the water quality impact area are considered. These three sections on major
water quality impact areas are preceded by a discussion of factors
controlling reservoir water quality, and followed by a list of references
for more in depth discussions.
GENERAL CONTROLLING FACTORS
Changes in the quality of water due to impoundment depend on many
variable characteristics. Some parameters are related to natural processes
while others are related to reservoir design and management. The major
stresses which seem to control the quality of water are:
(a) The quality of the inflowing water
(b) Climatic controls, including precipitation, temperature,
insolation, wind, and evaporation
(c) Inorganic chemical reactions, including chemical
precipitation, complex formation, and oxidation-
reduction reactions
(d) Mor-phometric controls, such as the size, shape, and
depth of the impoundment
(e) Biological controls with regard to effects of living
organisms upon organic and inorganic materials
(f) Management controls, including factors manipulated by
man to regulate conditions within the reservoir or
downstream from it, such as retention time. (Love and
Slack, 1963).
Brief descriptions of these characteristics follow (Burdick and
Parker, 1971):
The quality of the inflow is of obvious importance in controlling
the water quality in an impoundment. Average values of the various water
quality parameters, as well as their variation with time, are of interest.
29
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In approaching prediction or simulation of reservoir water quality, the
quality characteristics of the inflow probably provide the most likely
starting point and are a baseline condition from which quality changes may
be measured.
Climatic controls, including precipitation, temperature, wind,
evaporation, and solar radiation, exert an influence upon both the inflow
quality and the processes which occur in the reservoir. Precipitation, by
controlling the inflow rate, affects the residence time of the water in the
reservoir and the dilution and mixing properties of the reservoir.
Temperature is of great importance physically, chemically, and biologically.
Water density, viscosity, vapor pressure, surface tension, and the
solubility and diffusion of gases are temperature dependent, as are the rate
and extent of chemical and biochemical reactions. The temperature effect on
water density is of major importance. It causes the phenomena of thermal
stratification, which presages many changes of reservoir water quality.
Wind influences evaporation, gas exchange, and mixing. Evaporation tends
to produce increases in concentrations of dissolved materials and may
represent a significant water loss in many reservoirs. Solar radiation
affects temperature and photosynthesis,
Inorganic chemical reactions include the actual mechanisms by
which many important quality changes occur. Included are solution,
precipitation, complex formation, and oxidation-reduction reactions.
Morphometric controls account for many differences in the behavior
of different impoundments. Length, depth, shape, and other parameters
descriptive of the physical system are important in generalizing and
comparing reservoir systems.
Biological controls are closely interrelated with inorganic
chemical reactions as the mechanisms of quality changes. The change may
arise from extraction of materials from the water, addition of materials to
the water, or promotion of oxidation-reduction reactions.
Management controls include any management practices in the
drainage basin and any operational practices of the dam and reservoir.
Reservoir outflow rate, water surface level control, reservoir site
preparation, and other such controls exert various influences upon the
water quality in the reservoir, and downstream from it.
30
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It is recognized that water quality may be improved or degraded
by impoundment. Some of the more significant beneficial and detrimental
effects of impoundment have been reported (Love, 1961). Important
beneficial effects of impoundment on water quality include:
(a) Reduction of turbidity, silica, color (in certain
reservoirs), and coliform bacteria
(b) Evening out of sharp variations in dissolved minerals
hardness, pH, and alkalinity
(c) Reductions in temperature which sometimes benefit fish
life
(d) Entrapment of sediment, and
(e) Storage of water for release in dry periods for the
dilution of polluted waters.
In addition, impoundment also has certain undesirable effects,
such as:
(a) Increased growth of algae, which may give rise to tastes
and odors
(b) Reduction in dissolved oxygen in the deeper parts of the
reservoir
(c) Increase in carbon dioxide and frequently iron,
manganese, and alkalinity, especially near the bottom
(d) Increases in dissolved solids and hardness as a result
of evaporation and dissolution of rock materials, and
(e) Reductions in temperature, which although sometimes
beneficial, may also be detrimental to fish life.
The prediction of impacts in these areas is a complex problem. The
complexity comes from the interrelationship of the parameters and from the
fact that the changes in the water quality occur not only at the reservoir
itself, but also downstream from the reservoir, and, in nearby estuaries.
In general, approaches to predicting the impacts in various locations are
essentially the same. However, the specific models developed at each
location differ from one another due to differing physical, chemical, and
biological processes taking place at various locations. Most models are
31
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•based on processes of mass, heat, or momentum balance, but because of
the assumptions and initial conditions used, solutions differ, thus the
resultant different models for the locations. For example, most reservoirs
of reasonable depth in the United States will stratify during the summer.
This situation presents difficult problems in the analysis of the temporal
and spatial distribution of temperature and dissolved oxygen. In contrast,
the temporal and spatial distribution of the impact areas in flowing
streams (downstream) or uniformly mixed reservoirs, are relatively simple
to characterize and quantify, because of their homogeneity. In the estuary
a different situation exists. Fluid motion is a complex interrelationship
of unsteady, nonuniform free surface flow due to tidal motion and fresh
water flow from upland rivers or impounded water low in DO and temperature.
The intrusion of the dense saline water from the sea will have an important
influence on the chemistry and biota of the estuary.
For convenience in this discussion, the reservoir impact on the
abiotic water quality parameters may be grouped into the following impact
areas: temperature, dissolved oxygen (DO), and chemical. These impact
areas are influenced by the abiotic and biotic parameters. It is important
to recognize that neither these impact areas nor their constituent parameters
can be separated into isolated compartments. They are characterized by a
high degree of interrelationship. In the following sections, the impact
areas as affected by reservoirs at the various locations are described,
along with a selected number of modeling and prediction techniques.
TEMPERATURE IMPACT AREA
Major Reservoir Influences on the Temperature Impact Area
Temperature is the single most important physical parameter of
water quality. The temperature affects other physical properties of the
water such as density, viscosity, vapor pressure, surface tension, and
solubility of gases and solids. Table 1 details the change in these
properties with change in temperature. Temperature also controls the
32
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biologic processes occurring within the water. Furthermore, temperature is
an important factor in determining its use for drinking, cooling, irrigation,
or recreational purposes. Temperature, therefore, is of great importance
physically, chemically, biologically, and in the intended use of the
impounded water.
The 'construction of a reservoir on a free-flowing stream
frequently results in two important changes relative to water temperature.
First, a seasonal pattern of thermal stratification may develop in the
reservoir. During the summer season, a warm upper layer may be separated
from a distinctly colder bottom layer by intermediate transition
zones. Such stratification is of major importance because it creates two
distinctly different and physically separated environments for biological
and physical/chemical activity. In contrast, the original free-flowing
stream was a single homogeneous environment. The second major water
temperature change resulting from impoundment relates to the water temperature
per se. Because water is held in the reservoir and downstream flow
rate is reduced, surface waters receive a greater amount of direct solar
heating. Thus, they are generally warmer than the original stream
temperature. Bottom layers, in contrast, are physically cut off from
such solar heating during periods of summer and winter stratification.
Therefore, bottom water temperatures are frequently cooler than the
previous free flowing stream temperature.
These two types of temperature related reservoir impacts,
stratification and absolute temperature changes, are of major signif-
icance because of their effect on biological and chemical activity
within the water body and their interaction with other water quality
factors. The original stream plant and animal community may be replaced
by two entirely new communities following reservoir construction; one
occupying the warm water zone and the second occupying the cold water
zone. Such species changes may be of direct importance, as when an
original trout population is replaced following reservoir construction
by species more adapted to warm water conditions such as bass and blue
gill. Reservoir temperature changes will alter not only the specific
plant and animal species present but also the general level of bio-
logical activity in the waters. Primary productivity of algae and
microorganisms in the warmer upper layers will be increased by impoundment
34
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while the productivity of the colder lower layer may be reduced.
Temperature changes also will have an important impact on the chemical
solubility of the water. Most importantly, the capacity of water to retain
dissolved oxygen decreases as water temperature rises.
Though the temperature changes and resulting impacts discussed
are the result of a complex interaction of factors, some general guidelines
may be suggested for identifying those conditions under which temperature
related impacts may be expected to be most severe. Reservoir, depth is an
obvious important factor. Only relatively deep reservoirs (20 to 30 feet
or more) will stratify. The nature of the inflow water is another important
factor. Potentially, undesirable temperature impacts will be more severe
when large quantities of warm water are introduced to the reservoir due
either to large summer inflows or upstream heating of the water through
man's activities such as power plant or sewage plant operations. When such
warmer inflows also possess high salt concentrations due to the acid mine
drainage, irrigation return flow, or soil conditions in the runoff area,
impacts may be particularly severe. The severity of temperature related
problems is also a function of some outflow characteristics. For example,
when the outflow is taken consistently from the bottom layer of the
reservoir the retention time of water in the upper layers of the reservoir
is greatly increased and thus water temperatures there are increased by
solar heating. Similarly, temperature related problems may result when
large withdrawals from the reservoir are made during the spring and fall
turnover period but relatively small withdrawals are made during the summer
and winter stratification periods.
Thermal stratification, a layering of water in the reservoir, is
a phenomenon induced by differences in temperature and thus density. In
shallow reservoirs where the isotherms tend to be tilted in the downstream
direction, stratification is relatively weak, and variation with depth of
other physical parameters is insignificant. This is a condition
characteristic of uniform, free flowing streams.
In deep reservoirs (30 feet or more) having a storage volume which
is large compared to the annual through flow, the isotherms are horizontal
during most of the year and strong stratification may develop during certain
seasons. For a well stratified reservoir, three distinct zones are developed
35
-------
with depth in the reservoir of the epilimnion (surface), the thermocline
(middle), and the hypolimnion (bottom). Thermal stratification causes
nonhomogeneous mixing of the reservoir which affects the extent of dilution
and mixing of the inflow waters. The main factors affecting the thermal
characteristics of a reservoir are its depth and the climatic regime of the
region. The temperature cycle can be summarized as follows:
Winter: Reservoir isothermal with depth. Water at
maximum density throughout; deep vertical motions
established by small wind forces at the surface.
Spring; Warming of surface. Epilimnion and upper layers
become uniform in temperature and relatively warm.
Water circulates here and is turbulent.
Hypolimnion (lower layer) remains undisturbed and
fairly cold. Thermocline (plane at which
temperature decreases most rapidly with depth;
also a zone of discontinuity between water masses)
subject to large vertical motions due to wind
motions.
Autumn; Epilimnion cools and increases in thickness.
Thermocline disappears; lake becomes isothermal.
Winter: Inverse of stratification is sometimes observed;
in large-deep lakes heat storage is great and ice
formation can be nil. (Anderson and Pritchard, 1951).
The classical pattern of thermal stratification in lakes or
reservoirs is shown in Figures 1 and 2 . Of particular interest are the
patterns of water circulation and salinity distribution in Lake Mead.
These patterns are controlled largely by density flows; which vary markedly
with seasons of the year. Three kinds of density flows are described—
overflows, interflows, and underflows (Love, 1961).
An overflow takes place when inflowing stream water spreads over
the surface of the reservoir. The overflow may travel for a considerable
distance and then mix with water near the surface by action of wind and
waves.
36
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Salinity, .---/I-*'*,
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Distance Below
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Distance Below
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FIGURE 2. SEASONAL SALINITY DISTRIBUTION AND
CIRCULATION PATTERNS, LAKE MEAD
(From Love and Slack, 1973; Love, 1961)
38
-------
An interflow takes place when the density of the inflowing water
is greater than that of water on the surface of the reservoir but less than
that of deep water. The inflowing water sinks to its own density level in
the reservoir and then spreads out laterally downstream.
An underflow takes place when the density of the inflowing water
is greater than that of the water at any level in the reservoir. The
inflowing water sinks to the reservoir bottom and travels downstream at or
near the bottom, usually along the old river channel.
Figure 2 shows seasonal salinity distribution and circulation
patterns in Lake Mead. In winter there is almost complete vertical mixing
of the water, and there is a simple circulation pattern. The inflowing
water is colder and more dense than the lake water and flows downstream as
an underflow. This pattern of flow would be expected to occur when the
temperature distribution is nearly uniform throughout most of the water
column. (See Figure 1, Feb. 6)
The greatest quantity of runoff occurs in the spring when the flow
is low in dissolved solids and high in suspended solids. At this time the
temperature of inflowing water is about the same as that of the surface of
the lake and the sediment settles out rather quickly. Thus, the inflowing
water proceeds into the lake as an overflow. Stratification of the lake
waters takes place with a vertical gradient of temperature and salinity.
The flow along the surface sets up a cellular circulation below 150 ft., which
causes an upstream flow along the bottom.
In the summer the inflow decreases in volume and increases in
salinity. The downstream travel of the river water takes place as an inter-
flow at a depth of about 80 ft.
In the fall, the, decrease in the temperature of the inflow causes
greater sinking of the river water along the bottom as an underflow until
it comes in contact with heavier water and then spreads out horizontally as
an interflow.
Techniques or Modes for Predicting Temperature in Reservoirs
The first step in the development of a temperature model is to
consider all factors involved in the exchange of heat between the water body
39
-------
and its environment. The degree of correlation of the predicted with the
measured data depends on how closely the model approximates the actual
physical situation modeled. Assumptions are made for specific situations
to give models varying in correlation and complexity. In general the
simplest models have poor correlation with the actual since all the sources
and sinks of heat to the medium are usually not accounted for, while the
more complex models have better correlation because of their inclusiveness.
In the following paragraphs, major characteristics of a selected number of
simple and complex models for predicting temperature are described. These
models are summarized in Table 2.
Turbulent Diffusion Models -
Turbulent diffusion models assume that the entire incoming solar
radiation is absorbed at the surface of the water. Several models in this
category will be discussed.
The simplest model in this category is a simple second-order
differential equation with constant vertical thermal eddy diffusivity
(Burdick and Parker, 1971):
™ , /ns
— = Dz where (1)
d t ^ /
dz
T = temperature (C)
t = time (t)
z = vertical coordinate measured downward from the
water surface (L)
2
Dz = vertical thermal eddy diffusivity (L /t).
Output of this model is the time-depth distribution of temperature
down the water column.
The primary inputs are:
• The initial and boundary conditions
• The vertical-turbulent diffusion coefficient
• Surface water temperature
40
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• Net rate of surface heat exchange
• Temperature exchange rate below the water surface.
The general assumptions of this model are:
• Net rate of surface heat exchange is a linear function of
the thermal exchange coefficient, and an equilibrium
temperature. Both the thermal exchange coefficient and
equilibrium-temperature are expressed as functions of the
wind speed, air temperature and humidity, and net
incoming radiation (Richardson, 1920; Ifeadi, December 5,
1973; Ryan and Harleman, April, 1971; Water Resources
Engineers, Inc., 1969)
• The temperature exchange below the water surface is
negligible
• Any horizontal plane is homogeneous with respect to
temperature.
Equation 1 may be slightly modified with specific assumptions to
give more specific models (Burdick and Parker, 1971): TIDEP I, TIDEP II, and
TIDEP III.
TIDEP I. The model is as given in equation 1 with the following
additional assumptions:
• Inflow and outflow are negligible
• The change of area with depth is small
• Variations of thermal exchange coefficient and
equilibrium temperature with time are cosine functions.
Simulation of Priest Reservoir showed this model to be
unsatisfactory. It is therefore not applicable for reservoirs whose inflows
and outflows will affect the temperature of the system.
TIDEP II. This model is the same as TIDEP I, except the influence
of a varying reservoir geometry with depth is included in the model. For
Priest Reservoir which was modeled, the variation of the area with respect
to depth was assumed as an exponential function. The correlation showed
slight improvement over TIDEP I, but was still not satisfactory, showing
that the model may not be applicable in reservoirs with significant
temperature inflows and outflows.
42
-------
TIDEP III. This model is the same as TIDEP II but evaluates an
additional parameter; namely, the effects of inflow and outflow temperature
(advection parameter) . The study of Priest Reservoir showed a significant
improvement over TIDEP II, showing the importance of inflows and outflows
as significant sources and sinks of heat in the reservoir.
Cornell Model. This model is also based on the turbulent diffusion
model but with variable vertical turbulent diffusion coefficient which is
given as a function of Richardson number. The general second-order
differential equation is (Sundaram, et. al., February, 1971):
8t
where
T = temperature (C)
t = time (t)
z = vertical coordinate, measured downwards (L)
!ST = the eddy diffusivity for the vertical transport
of heat
= K,T (1 + c^R.)"1 (Schlichting, 1955)
Ho 1 i
IL = the eddy diffusivity under identical environmental
conditions, but on the absence of stratification
a = empirical constant
Ri = Richardson number (Richardson, 1920; Pritchard, 1960)
11
2 9z
= - a g z —2~
w*
w* = /s/p the friction velocity
s = surface shear stress induced by wind
p = density of water
a = coefficient of volumetric expansion of water
g = acceleration due to gravity.
43
-------
Output of this model is the time-depth distribution of
temperature down the water column in the reservoir.
The general assumptions of the model are:
• Net rate of surface heat exchange is a linear function of
thermal exchange coefficient and the equilibrium
temperatures
• Vertical diffusion coefficient is variable, a function of the
Richardson number.
• Horizontal plane is homogeneous with respect to
temperature
• Temperature exchange below the water surface assumed
negligible.
The primary inputs are:
• The initial and boundary conditions
• The eddy diffusivity, based upon
The temperature of the reservoir at maximum spring
homothermy
Net rate of surface heat exchange.
Specifically, these primary inputs are:
• The variation of the equilibrium temperature over the
water body of the reservoir. The quantities depend on
the climatic conditions above the water body, and
methods of determination are discussed elsewhere
(Sundaram, et.al., November, 1969).
• The heat exchange coefficient. This is also a function
of environmental conditions above the water, and the
method of determination is discussed elsewhere
(Sundaram, et.al., November, 1969).
• The annual variation of the average wind speeds above
the water body. This is used in the calculation of the
Richardson number (Munk and Anderson, 1948).
On the study done with Cayuga Lake (Sundaram, et.al., February,
1971), the model gave an excellent correlation with observed data, thus it
44
-------
was recommended applicable to stratified lakes and reservoirs in temperate
regions. However, the same study showed that the model is not applicable to
reservoirs in which the area of cross section changes with depth. Studies
by other workers (Ifeadi, December 5, 1973) using the model have found its
correlation unsatisfactory.
Based on the basic relationship of Equation 2, other specific
models were developed. One was on the effects of thermal discharges and the
other was on the effects of interfacial mixing (Ifeadi, December 5, 1973).
Internal Radiation Absorption Models -
The internal radiation absorption models consider that solar
radiation is absorbed both at the surface as well as at all depths within
the water body to which the light penetrates. It has been observed that the
neglect of internal heat absorptions (as in turbulent diffusion models)
leads to artificially large values of eddy diffusivity (Dake and Harleman,
April, 1969). Therefore, the exclusion of internal absorption makes the
turbulent diffusion models of limited applicability. Several models will
be discussed. They are very similar in their mathematical development,
however they differ in their solution algorithms.
MIT Model. This model accounts for internal radiation absorption,
boundary heat sources and sinks, and heat transport by advection, convection,
and diffusion (Ryan and Harleman, April, 1971; Huber and Harleman, 1968;
Huber, Harleman, and Ryan, April, 1972).
The output of the model is the prediction of the vertical temperature
profile and the hydraulics of stratified flow.
Major geometrical simplifications and assumptions leading to the
development of the model are (Ryan and Harleman, April, 1971):
1. Thermal gradients exist in the vertical direction only
2. Heat transport by turbulent mixing is accounted for
only in the epilimnion region and only during times at
which the temperature-induced density profile is unstable
3. Solar radiation is assumed to be transmitted in the
vertical direction only
45
-------
4. The sides and bottom of the reservoir are assumed to be
insulated, the only heat crossing the boundaries (apart
from the surface) is via inflow and outflow
5. The density (p), specific heat (c) , and the coefficient
of molecular diffusivity (a) are assumed constant in all
heat budget and heat transport calculations
6. Solar radiation energy, transmitted by the water and
intercepted by the reservoir sides, is assumed to be
distributed uniformly over the cross section at the
depth of interception.
7. Solar radiation is absorbed directly in the body of the
fluid, as well as* at the surface
8. Convection in the epilimnion is accounted for by
allowing mixing to take place whenever the temperature
gradient (9T/3y) is negative, *y is elevation, positive
upwards)
9. Inflow enters the reservoir water column at the level at
which its density matches that in the water column (NO
outrace mixing complication). Outflow is centered about
the level of the outlet, i.e., linear temperature gradient
in the vicinity of the outlet.
10. Gaussian inflow and outflow velocity profile is assumed
11. Outlet appears as a line sink, though in practice it is
usually rectangular
12. Withdrawal may take place from several levels, single or
concurrently
13. The vertical advective velocity is obtained by requiring
that the continuity condition is satisfied at each level
14. The surface level is calculated as a function of the
initial surface level and the cumulative inflow and
outflow
15. Entrance mixing affects both the inflow and outflow
velocity profiles and hence the vertical advection terms.
Entrance mixing of 100 percent (or mixed inflow rate
twice the stream inflow rate) is assumed.
46
-------
Using the above assumptions and model characteristics, a basic
heat transport equation is obtained from consideration of heat flow through
a schematized control volume of the reservoir, thus (Ryan and Harleman,
April, 1971):
1 I- V(y)A(y)T(y)
A(y)
uo(y)B(y)T(y)J
(3)
where
T(y) = temperature at elevation y
V(y) = vertical velocity at elevation y
i.(y) = inflow velocity at elevation y
<}i(y) = radiation transmission at elevation (y)
outflow velocity at elevation y
inflow temperature
area at elevation (y)
t = time
a = molecular diffusivity
y = elevation (positive upwards)
uo(y) =
T. =
A(y) =
Equation 3 is solved numerically by explicit method with one
initial condition,
T + T for all y at t = 0 (Beginning of spring),
and two boundary conditions; namely, heat is conserved at the water
surface and the reservoir bottom. Detail development and solution are
given in Ryan and Harleman (1971).
47
-------
The required input data are pertinent hydrological and
meteorological parameters such as:
1. Solar radiation
2. Atmospheric radiation
3. Air temperatures
4. Relative humidities
5. Wind speeds
6. Streamflow rate
7. Streamflow temperature
Data from Fontana Reservoir were used to verify the mathematical
model. The prediction was satisfactory. This model has wide applicability.
Water Resources Engineers Model -
This model also uses the internal radiation absorption approach.
It is a general heat budget equation of the diagramaticized reservoir
(Orlob and Selna, January, 1968).
The output of this model is the temperature distribution, and
stratified flow patterns in the reservoir.
The general model is given as (Orlob and Selna, January, 1968):
a6 = a
— + (
-------
1
water temperature
temperature of inflowing water
h = heat flux per unit of water volume from external
solar energy sources
A = coefficient of effective diffusivity
fl - "
6z ~ ¥1
C = heat capacity of coats
p = density
= advection velocity normal to the plan of a
<(> = flow withdrawn from the slice at an impoundment
outlet
. = flow advected to the slice in the horizontal
plane
Major assumptions are:
• Vertical energy transfer down the water column
• Net shortwave energy distribution function beneath the
water surface is a decaying exponential function
• The effective mixing processes which occur in the
epilimnion are accounted for in the model by a variable
effective diffusion coefficient
• Density profile is represented by a step function.
The primary input data are: Hydrologic, meteorologic, and climatic
conditions of the reservoir. Specifically they include cloudiness, dry-bulk
temperature, wet-bulk temperature, barometric pressure, and wind velocity.
Researchers have verified this model and found it to have great merit
(Bacca, et.al., August, 1973). The following virtues have been cited:
• Extensive field application (e.g., Hungry Horse Reservoir,
Lake Roosevelt, Fontana Reservoir, etc.)
• Breadth of documentation (Water Resources Engineers, Inc.,
a
1969 ; Water Resources Engineers, Inc., August, 1968; Water
Resources Engineers, Inc., 1969 )
• Efficiency of computation
-------
• A quasi-two-dimensional description of the temperature
patterns, and
• Finer longitudinal discretization of a reservoir.
The prime advantage of this model is that it can be used to obtain
more detailed descriptions of temperature structures, flow patterns, and
quality states.
Temperature Prediction Downstream
The temperature prediction in the deep reservoir differs from
downstream and estuary prediction approaches. The major difference comes
from the stratification of deep reservoirs. Downstream and estuary are
continually mixed by the action of gravity flows, current, and wind agitation.
To a lesser extent shallow reservoirs are mixed by wind agitation. Therefore
they can be considered to be uniform in temperature with vertical temperature
profile.
The major temperature related change in stream conditions
occurring downstream from a reservoir is the replacement of a relatively
homogeneous stream temperature condition with a condition of zones of
markedly different temperatures. Immediately downstream of the reservoir
outfall, water temperatures will be colder than natural stream conditions if
the water is withdrawn from the lower layers of the reservoir. Farther
downstream reduced flow will result in warmer stream temperatures through
solar heating. Between these two zones of colder and warmer temperatures, a
third zone will exist within which water temperature rises rapidly with
distance. These temperature changes are important because of their impact
on stream ecosystems and organisms. Marked temperature changes will cause
alteration in the plant and animal species present in the stream, and in
their rate of growth. Biological activity is highly temperature dependent
and as a rough rule of thumb can be estimated as such activity would increase
by the factor of 2 for each five degree Centigrade rise in stream temperature.
Downstream temperature conditions will also influence chemical characteristics
of the stream and chemical reaction rates. For example, the cooler water
immediately below the outfall will possess higher levels of dissolved solids
50
-------
in comparison to free flowing stream conditions. Since flow downstream
from the reservoir will be reduced, at least during some portions of the
year, downstream temperatures will be much more dependent than previously
on the temperature conditions of new downstream inflows. Downstream
tributaries with sewage or power plants, for example, may produce more
significant temperature increases than previously. Conversely, any colder
water tributaries from snow runoff will have a greater cooling effect than
they would have had on the original freeflowing stream.
These potential downstream temperature effects are primarily
dependent upon the source and rate of withdrawal from the reservoir and on
the downstream tributary conditions. The potential for adverse impacts will
be greatest when reservoir outflows are taken totally or primarily from the
lower, cooler zone of the reservoir, and when irregular withdrawal rates
result in periods of substantial reduced flow.
Temperature prediction in rivers and estuaries involves a complete
heat balance of the body of water, which accounts for all heat initially
present in the water and all heat that flows into and out of the water body
during an interval of time.
The general time rate of temperature change is (Raphael, 1962):
dt Q A + m. (t.-t )
w _ _^t i i w'
de m
w
where
t = river water temperature
m = river water mass
w
m. = inflow mass of water
t. = inflow temperature of water
Q = total net heat transfer/area
A = area
The output of the model is the temperature profile. The
primary input data are:
51
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• Water body dimensions
• Flow and temperature characteristics
• Climatological and weather data.
The model is applicable in a uniform temperature region, and not
applicable where a thermocline exists.
DISSOLVED OXYGEN AND BOD IMPACT AREA
Major Reservoir Influences on Dissolved Oxygen
The quantity of dissolved oxygen (DO) in the impoundment is a
primary indicator of biological activity which in turn influences other
chemical and biological activities of the water body such as biochemical
oxygen demand (BOD), acidity, alkalinity, pH, etc. Aquatic life is oxygen
dependent, as is the self-purification capacity of water released from an
impoundment. Absence of dissolved oxygen may produce anaerobic conditions
and resultant odors at the site. DO is known to vary over time and depth of
the impoundment, thus the reduction of DO in the hypolimnion of thermally
stratified impoundments following the onset of stratification during the
summer season.
Three important types of dissolved oxygen impacts may be produced
by reservoir construction. Thermal stratification discussed previously
produces not only distinct temperature zones but also dissolved oxygen content
zones. The colder bottom zone may display a distinct oxygen deficiency due
to the lack of mixing and surface reaeration and due also to the increased
dissolved oxygen uptake by chemicals released from the bottom sediments
through the activities of anaerobic organisms. A second potentially major
impact is that reaeration of the surface layer may be reduced and may become
more dependent on climatic conditions, especially wind, rather than on flow
rate. Since the surface waters are warmer their capacity to retain the
dissolved oxygen will be reduced. The general effect of. there impacts is that
both the upper and lower zone may show lower levels of dissol od oxygen
than were present in the free flowing stream.
These dissolved oxygen changes are of great significance because
of the sensitivity of fish and other aquatic organisms to dissolved oxygen
52
-------
levels. Reductions in dissolved oxygen may produce major changes in the
species composition of the reservoir. These dissolved oxygen conditions may
also produce a cycle of major stress periods occurring primarily in the late
summer and fall when warm surface temperatures and algae die off may produce
significant fish kills. Dissolved oxygen deficiencies in the bottom layer
of the reservoir may also contribute significantly to the release of toxic
chemicals trapped in bottom sediments since low DO levels will favor the
activity of anaerobic organisms. Because dissolved oxygen levels are closely
coupled with water temperature, the conditions under which the oxygen
deficiencies may occur are similar to those under which marked temperature
changes may take place. Oxygen deficiencies may occur in reservoirs deep
enough to permit thermal stratification. Deficiencies may also result if
there is little summer inflow and a long retention time. Conditions of high
summer temperature and little wind mixing will also present prime
circumstances for oxygen deficiencies. If the water flowing into the
reservoir is either warm or high in salt concentrations the water's capacity
to retain dissolved oxygen will also be reduced.
Potential sources of oxygen for the reservoir system include:
(a) the inflow, (b) atmospheric reaeration, and (c) photosynthesis. The
potential oxygen sinks are: (a) the outflow, (b) oxidation reactions,
including biochemical oxidation of soluble or suspended organic materials
(BOD), biochemical oxidations occurring at the mud/water interface, and
occasionally chemical oxidation reactions when chemically reduced products of
anaerobic decomposition are transported from a zone of oxygen deficiency to
an aerobic area, and (c) respiration of animals and green plants in the
absence of sunlight (Burdick and Parker, 1971).
The magnitudes and importance of the various sources and sinks vary
quite widely in different water body systems and these factors may vary with
time as well as location within the same water body. To a very large extent
the variability of the factors involved in the oxygen balance of reservoirs
is controlled by the temperature, the thermal density structure, and the
hydraulic properties of the reservoir. For this reason, any comprehensive
consideration of the reservoir oxygen balance must first consider the
temperature distribution and its changes with depth and time as discussed
above.
53
-------
Since the primary sources of oxygen in a reservoir are usually
more closely related to the reservoir surface zones (atmospheric reaeration,
photosynthesis, and sometimes inflow), the development of thermal
stratification (which changes the vertical mixing characteristics of the
reservoir) reduces the rate at which oxygen is supplied to the deeper zones
of the reservoir. This fact becomes even more significant when it is
considered that a considerable fraction of the overall potential reservoir
oxygen sinks frequently lie below the thermocline through which oxygen
transport is inhibited.
Another important aspect of the reservoir thermal structure, in
addition to the hydraulic implications, is the temperature itself. An
example of such temperature effect is shown in Figure 3 . Here impoundment
effects and temperature with respect to deoxygenation rate, K^, and
reaeration rate, K~, are depicted. It is observed that impoundment, KL , at a
given temperature is unchanged, while the value of K at any temperature is
significantly reduced (Krenkel, Thackston, and Parker, February, 1969). In
the hypolimnion, where the temperature remains somewhat low, the rate at
which oxygen is extracted by biochemical oxidations, both within the water
body itself and at the mud/water interface, is somewhat lower than it would
be at higher temperatures. At the higher epilimnion temperatures, oxygen
uptake proceeds at a more rapid rate, but, since oxygen is usually more
readily available in this zone, its more rapid 'removal may be less critical.
Another important aspect of temperature is its effect upon the solubility of
oxygen. Oxygen is more soluble in water at lower temperatures, consequently
a higher concentration of oxygen exists in the hypolimnion of an impoundment
at the onset of stratification than if the temperature were higher. This
fact, coupled with the reduced rate of hypolimnion BOD exertion noted before,
may represent a slight positive effect upon the oxygen conditions of the
hypolmnion. In the epilimnion, with the progression of warmer temperatures,
the oxygen solubility is decreased while the rate of oxygen utilization is
increased, which is a somewhat negative effect. An additional consequence
of reduced oxygen solubility in the epilimnion is that a major portion of
the oxygen produced by photosynthesis may be lost to the atmosphere,
thereby reducing much of the potential benefit of photosynthesis. (As noted
previously, the death of the photosynthetic organisms in the epilimnion and
54
-------
20
18
16
14
I 12
10
^
o
r—
^J
Deoxygenation
Coefficient - k,
Reaeration
Coefficient - k
Free
Reaeration Coefficient -
River Impounded—^.
10 15
TEMPERATURE, C
20 25 30 35
FIGURE 3. VARIATION OF ^ AND k2 WITH TEMPERATURE
AND RIVER CONDITION (O'Connel and
Thomas, 1965)
55
-------
their subsequent sedimentation into hypolimnion can significantly affect the
oxygen resources of the hypolimnion.) Since the dissolved oxygen concentration
in the epilimnion is reduced by the warmer temperatures, the gradient of
oxygen concentration across the thermocline may become reduced, leading to an
additional reduction of the oxygen transport rate across the thermocline to
the hypolimnion.
Figure 4 summarizes the major factors affecting the oxygen balance
of reservoirs. The magnitudes and effects of the various factors are quite
inter-related and variable in time and space. In attempting to describe
reservoir oxygen conditions, it quickly becomes apparent that the constraints
of the system being considered determine to a significant extent which sources
and sinks of oxygen are of major importance in various zones of the reservoir.
Recognizing this fact, it can be anticipated that somewhat different
assumptions would be necessary for developing descriptions for stratified, as
opposed to unstratified reservoirs, or for reservoirs with high level outlets
or low level outlets, or for stratified reservoirs with inflow to the
epilimnion as opposed to inflow to the hypolimnion. In some cases it might
be desirable, for instance, to develop separate descriptions for the
epilimnion and hypolimnion.
A further constraint is concerned with the magnitude of the inflow
and outflow. The distinction was made by Kittrell (Kittrell, 1959) between
"storage reservoirs" and "main stream reservoirs". Storage reservoirs were
characterized as being rather deep, having large surface areas, having
considerable fluctuations of surface elevation, having low flow velocities
(long residence times) and usually developing persistent thermal
stratification with hypolimnetic oxygen deficiencies during the summer
months. Main stream reservoirs were viewed as being shallower, with much of
the water being confined to the original river channel, having rather
constant surface areas and water surface elevations, having high flow rates
(short residence times), and developing less persistent thermal stratification
and less severe hypolimnetic oxygen deficiencies (if any at all). Carried to
the extreme, such a comparison^would distinguish between a lake with
essentially no outflow and an essentially unimpounded river. From the
standpoint of mathematical description, a distinction between these
contrasting cases would need to be made with respect to the dimension in which
56
-------
HIGH LEVEL DISCHARGE
ii*
LOW LEVEL DISCHARGE
Inflow may be'
i . lurface overflow
ii. bottom underflow
iii. mixed through depth
(a) UNSTRATIFIED RESERVOIR
3 ..
4 ^^l:7 <5> w • (±!) (|0^
Surface inflow
Inflow may be1
f . bottom underflow
ii. interflow
(b) STRATIFIED RESERVOIR
MAJOR FACTORS AFFECTING OXYGEN BALANCE
I. CHANCE OF STORAGE
2. TRANSPORT ACROSS THERMOCLINE
3. ADVECTION INFLOW
4. ADVECTION OUTFLOW
5. INTERNAL OXYGEN CONSUMPTION
6. BOTTOM AND VEGETATION DEMAND
7. SEDIMENT DEMAND
a NET PHOTOSYNTHESIS
ft SURFACE REAERATION
10. TEMPERATURE INDUCED CHANGES
(SOLUBILITY)
FIGURE 4 . IDEALIZED REPRESENTATION OF OXYGEN BALANCE
CONSIDERATIONS FOR VARIOUS PHYSICAL CONSTRAINTS
(From Burdick and Parker, 1971)
57
-------
the primary changes of oxygen occur, since the application of three-
dimensional models has not yet proven to be feasible. For the lake or
storage reservoir in which the major oxygen changes occur in the vertical
direction, a one-dimensional model may be a satisfactory approximation.
Similarly, a one-dimensional approximation may be applicable to a river or
main stream reservoir case where changes occur primarily in the longitudinal
direction. In the transition between the two cases, mathematical
description becomes more difficult, although combinations of the simpler
models may provide a suitable approximation.
Predicting Dissolved Oxygen (DO) in Reservoirs
Modeling DO in impoundments is complicated by the existence of
stratification, differing water quality conditions in a stratified flow
medium, and the complexity of the entire reservoir hydrodynamics. Only a few
models are applicable to deep stratified reservoirs. Many are applicable
to the reservoir euphotic zone (defined as the depth by which 99 percent
of the incident light is observed), and are used in predicting DO in
flowing streams. Some of these models are discussed below and summarized
in Table 3.
One-Dimensional Mathematical Model -
This is an oxygen balance model for an incremental volume of
surface area A, and depth, dz. It involves formulating the rate change in
total mass of DO within the horizontal slice and equating it to the sum of
all DO import and removal rates, thus (Bella, October, 1970)
dz = Fi - Fo + S , (6)
where
C = the DO concentration within the slice
t = time
dz = incremental depth
58
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59
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Fi = the DO flux into the slice
Fo = the DO flux out of the slice, and
S = the sum of all DO sources and sinks acting
on the slice.
Based on the above oxygen balance, the general vertical one-
dimensional DO equation for lakes was developed: (Bella, October 1970)
9C
9t
1
A
r f 9C\
8 (DvA — )
9z
3(UAC)
- qeC + qiCi + (P - R)
(7)
where
C = the DO concentration
A = horizontal area, constant with time
Dv = the vertical dispersion coefficient
U = the average water velocity across the horizontal
area
qe = rate of water exported per unit of depth
qi = the rate of water imported per unit of depth
Ci = the DO concentration in the imported water
R = the rate of DO change per unit volume due to
total community respiration, such as algae
respiration, BOD removal, and shore-bottom
demand
P = rate of oxygen production by algae
The output of the model is the prediction of DO distribution with
depth and time in stratified lakes or reservoirs. The model can be used
to determine hypolimnetic oxygen demand rates by way of explicit finite-
difference approximation.
Primary assumptions are that:
• Horizontal areas are constant with time and
• Horizontal DO variations are small compared with vertical
variations.
60
-------
The one-dimensional continuity equation for a constant area is:
d(UA) . ,_.
dz - qi - qe . (8)
Input data to the model are:
• The flux of DO at the water surface, ?„ which is given as:
n
FH ' AHVCS - CH> '
where
IL. = the surface DO transfer coefficient
C = DO concentration at the surface
D
CT7 = DO concentration below the surface.
n
• Temperature profile
• Vertical dispersive coefficients
• DO sources and sinks acting on the water body.
Equation (7) may be further simplified to take care of special
situations (Bella, October, 1970). The model has been verified in stratified
flows, and correlation was found satisfactory.
Statistical Method -
This method was used to estimate the DO of a completely mixed
reservoir. The data obtained were statistically analyzed ard the regression
equation, which described conditions at the sag point downstream from a waste
input was (Krenkel, Cawley, and Minch, September, 1965):
0.001
D0 = 57.8 , (10)
61
-------
where
Q = capacity
T = temperature.
Multiple Regression Technique (Principal Component Analysis) -
Principal component analysis is said to minimize the effects of
intercorrelations among the "independent" variables and yields a prediction
equation in which the coefficient of an "independent" variable, X, more
nearly represents the change in Y per unit change in the corresponding X.
Three dependent variables, retention time, temperature of the outflow, and
distance are combined in a regression equation, thus
Y = a + b1X1 + b£X2 + b3X3 + b^ + b X + b , (11)
where
Y = decrease in DO concentrations (mg/liter) between
1 and the date for which a DO prediction is
desired
a = constant determined from the solution of the
equation
X, = T/10 where T = time (days) from April 1 to the
date for which a DO prediction is desired.
X2
where
n = the number of 10-day time increments after April 1
ATe = increase in temperature, ( C) between April 1 and
the date for which a DO prediction is desired,
and
62
-------
V T
X3 = J1 loir ' (13)
where
H = the distance (feet) above the centerline of the
power intake at which the April 1 inflows exists
on the date of interest, assuming no mixing in
the pool and that water is drawn from the pool
at the elevation of the intake only.
Primary input data are the operational data for the reservoir, and
the predicted values of the temperature of the outflow.
This model showed satisfactory prediction of DO values for Watanga,
South Holston, and Norris reservoirs. However, their stratification
conditions were not stated.
This technique has the advantage of being expanded to take several
pertinent water quality factors (such as BOD, COD, nutrients, etc.) in the
inflow into account and thus allowing more accurate predictions to be made
for reservoirs covering a wide range of project design, operation, and water
quality conditions (Churchill and Nicholas, December, 1967).
Water Quality Model -
This model approximates the formulation of the overall quality
problem in the reservoir by partitioning the mechanisms of change of some
water quality parameters into mass transport and chemical reactions.
Utilizing the segment-element discretization, the mass transport equations
are derived for the finite layer (element) of solute transport as (Bacca,
et.al., August, 1973):
2 A 3z AAz Vi i xo J
o Z
h (k)_ hc(k)Y (k)
i i xo '
63
-------
where
C = concentration of k constituent, k = l,2,...,n
(k)
C. = concentration of upstream flow
D = effective diffusion coefficient
z
A = horizontal surface area of water plane for element
Q = vertical flow through element (layer)
= horizontal inflow (i) ancj outflow (o) to element
Az = element thickness
This model may be used to describe the spatial and temporal
variations of several reservoir water quality parameters, such as dissolved
oxygen, BOD, algae populations, and nutrient materials.
Main assumptions are:
• Vertical gradients in area and diffusion coefficients are
neglected
• Boundary conditions for the transport equations as
fv\
8CV '/8n = 0 at the bottom and air-water interface.
This model has not been verified and thus its correlation with
natural systems is not yet known.
DO and BOD Prediction in Streams and Estuaries
Downstream dissolved oxygen impacts parallel temperature impacts.
That is, a stable and homogeneous stream environment is replaced by an
unstable environment varying markedly over time and distance. Extreme
dissolved oxygen deficiencies may occur immediately downstream from the
reservoir, especially if the outflow water is withdrawn from the reservoir's
bottom layers. Periods of reduced flow will result in a lowering of the
reaeration rate downstream from the reservoir. The downstream reach
previously homogeneous in regard to dissolved oxygen may show a steep
gradient with DO levels increasing with distance from the reservoir. Because
of reduced flows downstream, tributaries to the main stream will become more
important determinants of dissolved oxygen levels. If waters are drawn from
64
-------
the lower portions of the reservoir they will be high in reduced chemicals
increasing the physical/chemical oxygen demand in the downstream reach.
The net effect of these impacts on downstream waters is that the capacity of
the stream to retain dissolved oxygen may be reduced at the same time that
the demand for oxygen for physical/chemical and biological processes may be
increased. Significant downstream oxygen deficiencies may thus be produced,
resulting in major changes in plant and animal populations of the stream.
Oxygen deficiency problems, like temperature problems, will be
greatest in a downstream area where water from the reservoir is withdrawn
only from the bottom layers and/or when wide variations in the rate of
withdrawal occur seasonally, producing periods of extreme low flow.
The general equation describing dissolved oxygen in streams,
estuaries and the euphotic zone of reservoirs may be represented as (Bacca,
et.al., August, 1973):
+ (P-R) + (P-R) (15)
s a
where
DO = dissolved oxygen, mg/1
k ,k ,k, = deoxygenation rates for carbonaceous, nitrogeneous,
and benthic BOD, / day
k~ = reaeration coefficient, /day
(DO - DO) = dissolved oxygen deficit
S
(P-R) ,(P-R) = photosynthesis and respiration rate for suspended and
attached algae, respectively
T = temperature
Lc = carbonaceous BOD, in mg/1
Ln = nitrogenous BOD, in mg/1
2
Ld = oval benthic BOD, in mg/m
H = average river depth, in meters
65
-------
Two simpler forms of Equation 15 describing the concentration of DO in streams
are those described by O'Connel, et.al. (1965), and Symnon, et.al. (1969), and
that of a pure mixed water. Stream DO prediction models are summarized in
Table 4.
- y) - KD + (R - P) (16)
where
D = oxygen deficit
t = time
K... = deoxygenation rate constant
La = total organic BOD
y = La[l - exp - K,t] BOD satisfied at any time
K« = reoxygenation rate constant (atmospheric)
R = rate of oxygen demand by algae, and
P = rate of oxygen production by algae.
An important assumption of this model is that sedimentation does
not occur. Also the model has a shortcoming in not predicting the DO
conditions of the hypolimnion where DO deficiencies appear. It is also
unable to account for the diffusive DO transport from the euphatic zone to
greater depths.
The model has been evaluated by the DO Probe Method (Langbien and
Durum, 1967) and its correlation found satisfactory. Therefore the model is
a useful method for studying the DO budget in streams, and euphotic impoundments,
It will also permit comparison of the DO budget from one impoundment to
another.
DO of Mixed Pure Water (Bacca, et.al., August, 1973) -
The rate of reaeration of well-mixed pure water is proportional
to the oxygen saturation deficiency, thus:
—- = k2 (DOs - DO) (17)
66
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67
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where
DO = dissolved oxygen concentration, mg/1
saturated dissolved oxygen concentra
reaeration coefficient: 0. 05-16. 0/day
DO - saturated dissolved oxygen concentration, mg/1
s
The value of DO for natural, unpolluted streams can be calculated from the
S
following equation:
DO = 14.652 - 0.41022T + 0.0079910T2 - 0.000077774T3
s
The model is not applicable in polluted streams.
Reaeration Coefficients -
The reaeration process is significantly influenced by temperature,
stream geometry, and stream hydraulics.
The reaeration coefficient has been found to vary with temperature
as:
K2(20) e(T~20) (18)
where
1.015 <. 9 ^ 1.047 (Bacca, et.al., August, 1973)
K_ = coefficient at temperature T
K2(20) - coefficient at 20°C.
Numerous equations have been developed to compute reaeration
coefficients based on stream geometry and stream characteristics (Texas
Water Development Board, May, 1971). However, most are extensions of a
basic equation given by Streeter and Phelps (Streeter and Phelps, 1958
[reprinted]):
68
-------
where
where
where
-n
o— (19)
D
u = mean stream velocity, ft/sec
D = mean stream depth, ft, and
c,n = constants for a particular stream in question.
Several reaeration coefficient models follow:
• General velocity-depth model (Bacca, et.al., August, 1973):
K = reaeration coefficient,/day
v = velocity, ft/sec
h = depth, ft
rl'r2'r3 = constants: 2.0-12.0, 0.6-1.0, 0.85-1.85
• Churchill, Elmore, and Buckingham (Churchill, Elmore, and
Buckingham, 1962):
Kf = 5.026u°-969D-1-673K2.31 (21)
u = average velocity in the stream, ft/sec
D = average depth of the stream, ft, and
= reaeration coefficient, (days)
69
-------
where
• Langbien and Durum (Langbien and Durum, 1967):
20 = 3.3 u/D1'33 (22)
u = mean velocity, ft/sec
D = mean depth, ft, and
K- = reaeration coefficient, (days)"-'-
• O'Conner and Dobbins (O'Conner and Dobbins, 1958). These
investigators proposed equations based on the turbulent
characteristics of a stream as follows:
For streams displaying low velocities and isotropic
conditions:
20
K2 - -HTT" (23)
±.D
For streams displaying high velocities and nonisotropic
conditions:
7n 480 D°-5S°'25
K2° = S.-2 x 2>31 (24)
D
where
S = slope of the streambed
D = mean stream depth, ft
u = mean velocity, ft/day
= reaeration coefficient, (days) "•'-
70
-------
and where D is the molecular diffusion coefficient
2 m
(ft /day) which can be computed by
_T T-90
D = 1.91 x 10 (1.037) (25)
m
Isotropic conditions are satisfied when Chezy's
coefficient is greater than 17, and non-isotropic for
values less than 17. 0'Conner and Dobbins (1958) have
shown that Equation 16 is generally applicable for most
cases.
Owens, Edwards, and Gibbs (Owens, Edwards, and Gibbs,
1964):
For streams with a velocity variation range from 0.1 to
5.0 ft/sec and depths from 0.4 to 11.0 ft:
V20 Q . -0.67/TVL.85 0 Qi
K0 = 9.4 u /D x 2.31
where
u = mean velocity, ft/sec
D = mean depth, ft, and
K9 = reaeration coefficient, (days)"
For streams with a velocity variation range from 0.1 to
1.8 ft/sec and depths from 0.4 to 11.0 ft:
K^0 = 10.1 IT °'73/D1'75 x 2.31 (27)
• Thackston and Krenkel (Thackston and Krenkol, February,
1969). This investigation included several rivers in the
Tennessee Valley Authority system and resulted in the
following equation for K- at 20 C:
71
-------
*
10.8 (1 + F°'5) x 2.31 (28)
where F is the Froude number which can be computed by
*
F = — (29)
/gD
*
and u is the shear velocity, ft/sec, which can be
computed by
u* = /DS g (30)
where
D = mean depth, ft
2
g = acceleration of gravity, ft/sec , and
S = slope of the energy gradient.
Dobbins (Dobbins, June, 1964):
.2772 C AE3/8 coth M
C,
K 4
2 TTT
where
/gh"
2
C4 = 0.9
CA = 1.0
A
gh
E = 30 v S
V = velocity in ft/sec.
S = river channel slope
72
-------
A = 9.68 + 0.054 (T-20)
V2
B = 0.976 + 0.0137 (30-T) '
2
g = gravitational constant, ft/sec
T = temperature, C
Photosynthesis and Respiration of Attached Algae and Benthic Plants -
The net rate of photosynthesis and respiration of attached algae
and benthic plants is given as (Bacca, et.al., August, 1973):
(P-R) = Ana cos (co t + <)> ) + A a cos (2 GO t + a ) (32)
3 J_ 3 3- Z 3. 3.
where
(P-R) = net rate of photosynthesis and respiration,
a ± (0.01-2.00), mg/1 per day
co = period, days
3
A ~,A0 , ,a = constants
-L £ 33
a
a . a
Photosynthesis and Respiration of Suspended Algae -
The rate of photosynthesis and respiration of suspended algae is
given as a two-term harmonic function of the form (Bacca, et.al., August,
1973):
(P-R) = A., cos (cot + ((>)+ A9 cos (2cot + a) (33)
S _L ^-
where
(P-R) = net rate of photosynthesis and respiration,
S ± (0.1-2.0), mg/1 per day
co = period, days
AI ,A?,>a = constants
73
-------
Biochemical Oxygen Demand -
A model using first order BOD reactions can be used to describe
the carbonaceous and nitrogenous components of BOD, thus (Bacca, et.al.,
August, 1973):
dL
-—- = - (kj 4- k!p L + P
dt 1 o c c
= kj (20) ec(T-20) ' (34)
dL
_JL = - kn T
dt kl n
(20) en(T-20) (35)
where
L = carbonaceous BOD, mg/£
c
k1 = deoxygenation coefficient
£
k» = sedimentation coefficient: 0.0-3.5/day
P = scour coefficient: 0.0-0.8 mg/& per day
k!r(20) = deoxygenation coefficient at 20°C: 0.0-
0.8/day
6c = temperature coefficient: 1.02-1.06
T = temperature, C
L = nitrogenous BOD, mg/&
k. = deoxygenation coefficient: 0.1-0.8/day
^(20) = deoxygenation coefficient at 20°C
6 = temperature coefficient: 1.05
74
-------
c = denotes carbonaceous
n = denotes nitrogenous
Second-order equations are also in the literature but they have
been observed not to predict BOD concentrations with any more accuracy than
the first order equations which require less data (Bacca, et.al., August,
1973).
Benthic Oxygen Demand -
The benthic oxygen demand is a steady state or first-order
reaction. This is given as (Bacca, et.al., August, 1973):
Lri
F- - Pc + k3 Lc
k4 = V20) ed" (37)
where
2
L' = areal benthic BOD, mg/m
k, = deoxygenation coefficient for benthic BOD
k,(20) = deoxygenation coefficient at 20°C: 0.0-
0.8/day
6, = temperature coefficient: 1.05
H = average river depth in meters
£
P , k_, L are defined above
c' 3 c
This equation is coupled to the carbonaceous BOD equation through the
Q
constants P , k_, and L .
c' 3 c
75
-------
CHEMICAL IMPACT AREA
Major Reservoir Influences on Chemical Constituents and Chemical Activity
The inflow water quality, the character of the reservoir soils, and
biological activity control the chemicals, trace elements, and chemical
reactions in reservoirs. Parameters like carbon dioxide, pH, alkalinity, and
hardness control the chemical activity and are interrelated through the
carbonate equilibrium relationships. They exert influences upon changes of
other water quality parameters too, as well as upon each other. Another
factor is the increased detention time of water in the reservoir which
provides a potential opportunity for slow reactions to come closer to
completion. Thermal stratification and its aligned effect on oxygen
conditions also influence the distribution of these parameters in reservoirs
with depth and time. For example, the hypolimnion of a stratified reservoir
tends to develop higher concentrations of free carbon dioxide, lower pH,
higher total alkalinity, higher hardness, and higher values of specific
conductance than the epilimnion (Burdick and Parker, 1971).
Several important changes in the chemical characteristics of a
stream may occur following impoundment. Longer retention time and increased
surface area, may increase evaporation and thus increase salt concentrations.
Reduced flow rates and incomplete mixing will result in increased
sedimentation and the trapping of nutrients in bottom sediments. The action
of anaerobic organisms may result in the release of chemicals or toxic
materials from bottom sediments. Finally, periodic surges of concentrations
of salts, nutrients, and toxic materials may occur at periods of spring and
fall turnover.
These changes are important for a number of reasons. They may
result directly in changes in the plant and animal population of the water
body. They will decrease the oxygen holding capacity of the water.
Trapping of nutrients may increase the biological activity in the reservoir
and thus produce algal blooms. Surges occurring during turnover periods may
result in the concentration of some materials not generally harmful reaching
toxic levels, for example iron or manganese. Generally toxic materials
otherwise trapped in bottom sediments such as mercury and copper may also
76
-------
be released. Such undesirable alterations in the chemical constituents of
a water body will be most likely to occur when the reservoir inflow is high
in nutrients or toxic materials such as pesticides, when the natural inflow—
particularly during summer—is greatly reduced but the inflow from industrial
or sewage plants is constant, and when these conditions are coupled with
temperature or dissolved oxygen conditions promoting a marked stratification
and turnover cycle.
The primary alterations and chemical characteristics downstream
produced by reservoir construction are: a reduction in nutrients and
suspended solid levels, an increase in dissolved solids level, and the
creation of a system more sensitive to new inputs from downstream
tributaries.
These changes may be of particular importance because of their
direct influence on plant and animal composition of the stream or on the
level of biological activity. They may also be important to the extent they
decrease the waste assimilative capacity of the stream. Perhaps more
fundamentally, they result in the creation of a fragile system highly
susceptible to outside stresses. Deleterious changes in stream chemistry
are most likely to be produced by the same conditions creating water
temperature and dissolved oxygen problems, that is, withdrawals from the
bottom layer of the reservoir and significant variation in the rate of flow
resulting in major periods of low flow. Chemical prediction models are
summarized in Table 5.
Effects on Nutrients
There is increased nutrient build up of fertility in reservoirs,
creating the same eutrophication problems that exist in many natural lakes.
Important factors are increased nitrogen and phosphorus retention and loss
of dissolved oxygen resources in the deep water hypolimnion, which may lead
to algal blooms and other aquatic plant problems. Other conditions at the
impoundment, such as light, suitable temperature, and quiescent water also
contribute to algal growth.
The sources of nutrients are varied. It has been reported that a
major source of nitrogen and phosphorus is the treated and untreated sewage
from cities. For example, it has been estimated that approximately 0.27 mg/1
77
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phosphorus and 1.35 mg/1 nitrogen are discharged from sewage (Churchill,
Elmore, and Buckingham, 1962). These values are higher than the minimum
values that could support objectionable population density of algae which
approximately 0.015 mg/1 for phosphorus, and 0.3 mg/1 for inorganic
nitrogen. Significant quantities of nutrients may find their way into
reservoir also from agricultural lands. The quantities leaving
agriculatural land are variable depending upon land use, slope, and soil
characteristics. Typical contributions of about 2 pounds of phosphorus per
acre per year, and between 0.06 to 3 pounds of nitrogen per acre by year
have been noted (Love and Slack, 1963). Fertilizer application, feedlots
and animal factories contribute -their share to water bodies, especially
when they are situated adjacent to water courses.
The nutrients that enter a given reservoir also recycle via the
biological system. The nutrient substance of a given species is released
upon death and decay and is made available for uptake by other organisms.
Both the nitrogen and phosphorus cycles are rather complex. They exist in
different forms and the recycle circle may be short to long. Another
complication is the occurrence of stratification. Ammonia tends to build up
in the hypolimnion of a stratified impoundment under reduced oxygen
«
concentrations due to ammonification of organic nitrogen, reduction of
nitrite and nitrate, and desorption of ammonium ions from the sediments.
Phosphorus apparently accumulates In the hypolimnion of a stratified
impoundment by sedimentation of organisms containing phosphorus from the
surface and by diffusion from chemically reduced bottom muds.
In the epilimnion, due to aerobic conditions, nitrate is the form
normally present unless it is extracted by the phytoplankton to form new
cell material.
At present, there are no available models for reservoirs to
predict, during the planning stages, what the absolute levels of nutrient
production are likely to be though approximations may be developed based
upon incoming stream loadings. The following two models deal instead with
the cycling of nitrogen and phosphorus.
79
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Nitrogen Model -
This nitrogen model consists of two parts: one considers the
effects of algae while the other includes ammonia-nitrate dynamics. The
concentrations of the various nitrogen forms are given by Ci and the rates
of reaction are given by Ji. The various nitrogen components are formulated
as a first-order model. The model is described by the equations (Bacca,
et.al., August, 1973):
where
dc±
dt
— _Tf 4-Tf1 _P T>A
— Jnv^n T J _ V_, . — \j r AVTT»
11 34 p WP
r ci ]
c1 + c3
(38)
dC,
dT
- J2C2 + J1C1
(39)
dc3
dt
T p P TD A
— •JoL'o ~ VT r A_T11
22 p TSIP
r s i
Lci + SJ
(40)
dC,
dt
- J0C, + D P
34 p
(Dz -
(41)
J1'J2'J3
P,Z =
ammonia concentration, mg/£
nitrite concentration, mg/£
nitrate concentration, mg/H
organic nitrogen concentration, mg/£
rate constants: 0.1-0.5, 5.0-10.0, 0.1-0.4/day
phytoplankton and zooplankton concentrations,
mg-C/1
ratio of nitrogen to carbon in phytoplankton
and in zooplankton: 0.17, 0.15 mg-N/mg-C
GP'GZ
DP>DZ
growth rates of phytoplankton and zooplankton,/day
death rates of phytoplankton and zooplankton,/day
P,Z,G ,G ,D , and D are formulated in the algae model.
Jr /j IT Lt
80
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For conditions where algae effects are not significant, simple
first-order ammonia-nitrate models are applicable:
~ " JC (42)
d ~ " 21
dC
dtT - +J2ci
Phosphorus Model
The phosphorus model developed by the same group of researchers
consists of three parts (Bacca, et.al., August, 1973):
• The first-order reactions of soluble phosphorus with
algae and with the sediments
• The first reaction model between soluble and sediment
phosphorus
• The second-order decay model for soluble phosphorus.
The concentrations of the phosphorus forms are given by Di, and
the rate constants for the reactions are given by li.
The equations for this model are (Bacc, et.al., August, 1973):
dt
Z2D2 + ^3 - V V (44)
dD2
__ . _ x^ + I]DI (45)
dD
IF" ' - ^3 + V ^P + (°Z - GZ)ADZZ (46)
where
81
-------
D = soluble phosphorus concentration, mg/£
D9 = sedimentary phosphorus concentration, mg/£
I1,I,),I» = rate constants: 0.1-0.7/day
P = phytoplankton concentration, mg-C/£
Z = zooplankton concentration, mg-C/A
A^ ,A^ = ratio of nitrogen to carbon in phytoplankton
and zooplankton: 0.17, 0.15 mg-N/mg-C
G , G = growth rates of phytoplankton and zooplankton,/
r £ -i
day
D ,D = death rates of phytoplankton and zooplankton,/
L i* ,
day
P,Z,G ,G ,D , and D are formulated in the algae model.
JT £ r Lt
The first-order model assuming that only reactions between
soluble and sedimentary phosphorus occur is given by:
dD
^ = - I]_D1 + I2D2 (47)
dD
' - + (48)
while the second order is:
dDl
Effect of Toxic Compounds
The behavior of toxic compounds in an aquatic environment is
variable and dependent upon the compound being modeled. Reservoirs do
contain iron, manganese and other compounds which can be toxic at higher
concentrations under certain environmental conditions.
Iron and manganese have been observed to cause color and turbidity
resulting in potentially increased costs and staining upon water use, and
incrustation of material that it contacts when reactions are conductive and
82
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are present in sufficient concentrations. The sources of these two metals
seem to be the rocks, soil, vegetation of the watershed, and sewage from
which the metals are transported to the reservoir in solution and suspension.
They are affected by oxidation and precipitation which may transfer them
downward in the reservoir. The increase and decrease in concentration of
the two metals roughly parallel the decrease and increase of dissolved
oxygen. Hence these metals are more abundant at the hypolimnion where
dissolved oxygen is depleted than at the epilimnion. Both the chemical and
the physical properties are important. Iron and manganese are both insoluble
in their oxidized forms, but are readily soluble in their reduced forms.
When the oxidation-reduction potential of the hypolimnion becomes sufficiently
reduced (usually due to severe oxygen deficiency) these ions become soluble
and diffuse from the bottom muds into the overlying water. As the mud
surface becomes reduced, phosphate and other ions are simultaneously
mobilized. Iron may precipitate as insoluble ferrous sulfide under
extremely reducing conditions. Under oxidizing conditions iron is
precipitated as ferric hydroxide, and manganese as manganic oxide or as the
manganous ion adsorbed on ferric or manganic oxide particles. The kinetics
of the oxidation may not be very rapid, so that these ions may persist for
some time in an oxidizing environment to produce the objectionable
characteristic taste and color (Burdick and Parker, 1971).
A simple decay model has been proposed to describe toxic
compounds (Bacca, et.al., August, 1973). This model accounts for any order
of decay desired, including zero order, and nonlinear behavior. The model
is given as (Bacca, et.al., August, 1973):
dT
dt
where
T = concentration of toxic compound
c
= rate constant (a function of toxic compound and media
characteristics experimentally determined.)
= order of decay.
83
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This decay model can be used to represent any of the mechanisms of exchange
such as chemical transformations, sedimentation, biological uptake, and
sorption.
Effect of Chemical Reactions
Impoundment can lead to significant shifts in the chemical reaction
in the impounded water. Due to stratification and increased detention time
of water body, several reactions take place. As has been discussed above,
BOD, DO, pH, alkalinity, hardness, and of course, temperature influence the
chemical equilibria of reactions within the system.
The reactions in reservoirs—principally carbonate equilibrium—
can be represented by the variation of an equilibrium constant, K. Thus
(Langbien and Durum, 1967) :
d
-------
REFERENCES
American Public Health Association. 1965. Standard methods for the
examination of water and wastewater, 12th ed. N.Y.
Anderson, E.R. and D.W. Pritchard. 1951. Physical limnology at Lake
Mead, Lake Mead sedimentation survey. Navy Electronics Lab., Rept. 258.
Bacca, R.G., W.W. Waddel, C.R. Cole, A. Brandstetter, and D.B. Cearlock.
1973. Explore I: a river basin water quality model. Battelle-Northwest,
Richland, Washington, EPA Project No. 211B00557.
Bartsch, A.F. 1968. Eutrophication problems in reservoirs. Seminar
conducted by Water Resources Research Institute, Ore. State Univ.,
Corvallis, Ore.
Bella, D.A. 1970. Dissolved oxygen variations in stratified lakes.
J. of San. Engr. Div., ASCE (SA5):1129.
Burdick, J.C. and E.L. Parker. 1971. Estimation of water quality in a
new reservoir. Rept. No. 8, Dept. of Env., Water Resources Engr.,
Sch. of Engr., Vanderbilt Univ. and U.S. Army Corps of Engineers.
Churchill, M.A., H.L. Elmore, and R.A. Buckingham. 1962. The prediction
of stream reaeration rates. J. of San. Engr. Div., ASCE, 7.
and W.R. Nicholas. 1967. Effects of impoundments on water
quality. J. of San. Engr. Div., ASCE (SA6):73-90.
Dake, J.M.K. and D.R.F. Harleman. 1969. Thermal stratification in lakes:
analytical and laboratory studies. Water Resources Research, 5(2).
Dobbins, W.E. 1964. BOD and oxygen relationships in streams. J. of San.
Engr. Div., ASCE, Proc. Paper 3949, 90(SA3):53-78.
Huber, W.C. and D.R.F. Harleman. 1968. Laboratory and analytical studies
of the thermal stratification of reservoirs. Hydrodynamics Lab. Rept.
No. 122, MIT, Cambridge, Mass.
D.R.F. Harleman, and P.J. Ryan. 1972. Temperature prediction
in stratified reservoirs. J. of Hydraulics Div., ASCE, HYA, 98:645-666.
Ifeadi, C. 1973. Personal communication to R. Bacca, Battelle-Northwest,
and to B. Benedict, Vanderbilt Univ.
Kittrell, F.W. 1959. Effects of impoundments on dissolved oxygen resources.
Sew. and Ind. Wastes, 31:1065-1078.
85
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Krenkel, P.A., W.A. Cawley, and V.A. Minch. 1965. The effects of
impoundments on river waste assimilative capacity. J. of Wat. Poll.
Contr. Fed., 37(9).
A.M. Thackston, and M. Parker. 1969. Impoundment and temperature
effect of waste assimilation. J. of San. Engr. Div., ASCE, Proc. Paper
6406, 95(SA1):37-64.
Langbien, W.B. and W.H. Durum. 1967. The aeration capacity of streams.
U.S. Geol. Survey Circ. 542.
Love, S.K. 1961. Relationship of impoundment to water quality. J. AWWA.
and K.V. Slack. 1963. Controls on solution and precipitation
in reservoirs. In Symposium on Streamflow Regulation for Water Quality
Control, Public Health Service Publ. No. 999-WP-30, Cincinnati, Ohio, pp 97-120.
Munk, W.H. and E.R. Anderson. 1948. Notes on the theory of the thermocline.
J. Marine Research, 1:276.
O'Connel, R.L. and N.A. Thomas. 1965. Effect of benthic algae on stream
dissolved oxygen. J. of San. Engr. Div., ASCE, Proc. Paper 4345,
91(SA3):1-16.
0'Conner, D.J. and W.E. Dobbins. 1958. Mechanism of reaeration in natural
streams. Trans. ASCE, 123.
Orlob, G.T. and L.G. Selna. 1968. Mathematical simulation of stratification
in deep impoundments. In Proc. of Speciality Conf. on Current Research into
Effects of Reservoirs on Water Quality, ASCE, T.R. No. 17, Dept of Env. and
Water Resources Engr., Vanderbilt Univ., Nashville, Tenn.
Owens, M., R.W. Edwards, and J.W. Gibbs. 1964. Some reaeration studies in
streams. Internat. J. Air and Water Poll., 8.
Parker, F.L. and P.A. Krenkel. 1969. Thermal pollution status of the art.
Rept. No. 3, Dept. of Env. and Water Resources Engr., Vanderbilt Univ.,
Nashville, Tenn.
Pritchard, D.W. 1960. The movement and mixing of contaminants in tidal
estuaries. Proc. of First Internat. Conf. on Waste Disposed on the
Marine Environment, E.A. Pearson, ed., Pergamon Press, pp 512-525.
Raphael, J.M. 1962. Prediction of temperature in rivers and reservoirs.
J. of Proc. of ASCE, 88:102.
Richardson, L.F. 1920. The supply of energy from and to atmospheric
eddies. Proc. Roy. Soc. A97:354.
86
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Ryan, P.J. and D.R.F. Harleman. 1971. Prediction of the annual cycle of
temperature changes in a stratified lake or reservoir, mathematical and
user's manual. Ralph M. Parsons Lab. Rept. No. 137, Dept. of Civ. Engr. ,
MIT, Cambridge, Mass.
Schlichting, H. 1955. Boundary layer theory, 2nd ed. McGraw-Hill Co.,
N.Y., pp 477-480.
Streeter, H.W. and E.B. Phelps. 1925. A study of the pollution and natural
purification of the Ohio River. Public Health Service Bull. 146,
(reprinted 1958).
Sundaram, T.R., C.C. Easterbrook, K.R. Piech, and G. Rudinger. 1969. An
investigation of the physical effects of thermal discharge into Cayuga
Lake. Rept. VT-2616-0-2, Cornell Aeronautical Lab., Buffalo, N.Y.
R.G. Rehm, G. Rudinger, and G.E. Merritt. 1971. Research on
the physical aspects of thermal pollution. Water Poll. Contr. Research
Series 16130 DPU, Cornell Aeronautical Lab., Inc., Buffalo, N.Y.
Symons, J.M.I., R.M. Clark, and G.G. Robert. 1969. .Management and measure-
ment of DO in impoundments. J. of San. Engr. Div., ASCE, Proc. Paper
5688, 93(SA6):181-209.
Texas Water Development Board. 1971. Simulation of water quality in streams
and canals, theory and description of the Qual-1 mathematical modeling
system. Austin, Texas, NTIS PB-202-975.
Thackston, E.L. and P.A. Krenkel. 1969. Reaeration predictions in natural
streams. J. of San. Engr. Div., ASCE, Proc. Paper 6407, 95(SA1):65-94.
U.S. Army, Corps of Engineers. 1970. Application of WRE reservoir tempera-
ture simulation model NPD computer program 723-1C5-G067. North Pacific
Division.
Water Resources Engineers, Inc. 1968. Prediction of thermal energy
distribution in streams and reservoirs. Walnut Creek, Calif., prepared
for the State of Calif., Dept. of Fish and Game.
a
1969 . Mathematical models for the prediction of thermal energy
changes in impoundments. Final project report presented to the Fed. Water
Poll. Contr. Admin,
1969 . Mathematical models for the prediction of thermal energy
changes in impoundments—computer application supplement. Prepared for
the U.S. EPA, Water Quality Office, Project No. 16130EKT, Contract No.
14-12-422.
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SECTION IV
ECOLOGICAL IMPACTS RESULTING
FROM RESERVOIR CONSTRUCTION
Ecology is concerned with all the organisms living in a habitat,
the physical chemical characteristics of that habitat, and the processes
which unite these two categories into a functioning system. It is a young
science less than 100 years old and has not yet acquired the huge body of
data about the environment nor reached the levels of sophistication in data
analysis that older sciences have. Ecologists do have considerable data on
many species and habitats, but they lack a detailed understanding of the
processes which connect species and habitats together into stable, produc-
tive ecosystems. This lack of complete knowledge about the functioning of
the ecosystem is reflected by the fact that few good measures of ecosystems
currently exist, and those available are best used as modifiers of other
parameters describing species or habitats. Obviously, it would be desirable
to possess such a firm understanding of ecological relationships that
environmental impacts could be quantitatively determined by FORMULAE. At
present, this is not attainable; thus, emphasis is placed on empirical
estimations based upon measured parameters.
Ideally, ecological impacts would be analyzed by establishing the
change in biota and habitats resulting from a project. This entails a
reference point from which change can be measured. This reference point
might be determined from existing data or from measured data taken in the
field. Monitoring programs would then be initiated to provide comparable
data over time. Once these data are available, impact would be identified
as the degree of change between commensurate units.
However, at this time, ecological impacts are typically predicated
in two ways: (1) professional judgment, based upon a knowledge of the biota
and habitat present, knowledge of the impending impact, results from similar
studies, and common sense; and (2) a few simulation models based upon
simplifying (and often unrealistic) assumptions and a knowledge of the biota
and habitat being emulated. Before any impact prediction can be made, some
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biotic and habitat measurements must be taken to reference the system being
stressed.
The purpose of this section is to document various types of
ecological impacts which may occur due to reservoir creation, and to pro-
vide guidance considerations to be used in the evaluation of environmental
impact statements on proposed reservoir projects. Six areas.of general
impacts resulting from reservoir projects are first identified. Each of
these general areas is then discussed in more detail, citing specific
impacts that have or may occur in certain circumstances and situation-
specific factors that may influence the magnitude or significance of
impacts. These presentations of terrestrial and aquatic ecological impacts are
followed by discussions of some important considerations in making baseline
measurements of environmental conditions. A bibliography of
literature on reservoir impacts completes the section.
GENERAL ECOLOGICAL IMPACT AREAS
The literature contains numerous references describing potential
or historically experienced environmental impacts of reservoir creation on
ecosystems. These references typically deal with site specific variables;
therefore, a general statement attributing specific effects to all reser-
voir projects is scientifically unacceptable. However, six general
ecological impact areas resulting from the creation of all reservoirs can
be identified as follows.
Terrestrial Impacts
A Given Amount of Terrestrial Habitat Will be Destroyed by Inundation -
That portion of the terrestrial habitat located within the area
of both the projected seasonal pool and most of the flood-pool will be
totally destroyed as a result of reservoir creation. The amount of habitat
that will be destroyed is determined by (1) purpose(s) of the reservoir,
("2) reservoir design, and (3) topography of the region in which the reservoir
89
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is located. Reservoir purpose(s) and regional topography determine reser-
voir design. The amount of habitat to be inundated is generally calculated
after determining these three factors. Once these data points are estab-
lished, a detailed topographic map is planimetered (at the operating water
column height) to determine acreage to be inundated.
The Land/Water Interface Within the Impact Region Will Increase After
Reservoir Formation -
As a result of both the seasonal and flood pools, the area of the
land/water interface will increase upstream from the dam. The amount of
increase can be calculated by planimeter methods from data derived from
(1) purpose(s) of reservoir, (2) reservoir design, and (3) topography of
the region in which the reservoir is located.
Two terrestrial habitats, the drawdown zone, discussed below,
and the uninundated terrestrial habitat are influenced by the increase in
the land/water interface. This influence is produced through modification
of the physical environment, i.e., radiant energy increases, a larger inter-
face for wind action, increased evapo-transpiration rates, etc, commonly
called, collectively, the "edge" effect (Odum, 1970; Treshaw, 1970).
Specific impacts are site unique and cannot be discussed in a general vein.
A New Habitat "The Drawdown Zone" Will be Created -
A release of water for hydroelectric power production, industrial
or domestic water supplies, irrigation and flood control usually occurs
throughout the year at most reservoirs. Water input seldom coincides with
water output; thus changes in the lake volume occur. As a result of this
fluctuation in water level, a belt of periodically inundated terrestrial
habitat is formed. This phenomenon has been described as a "bathtub ring".
Periodic changes in water levels tend to restrict vegetation
growth and establishment in the drawdown zone. Factors that influence
90
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growth and establishment are (1) duration of flooding, (2) season in which
inundation occurs, (3) sedimentation, and (4) species present within the
drawdown zone.
Although an occasional inundation for a short period of time
during the dormant or early spring season will not affect many tree species,
some upland hardwoods will not tolerate even short-term inundation. Other
species can withstand short periods of inundation if sedimentation does not
occur. Seedlings can also withstand periodic inundation during the dormant
season and even brief flooding during the growing season. However, if
deposits of sand or silt are laid down (3" or more), the roots tend to be
smothered.
Shrubby and herb-type vegetation may or may not vegetate a draw-
down zone. This depends upon (1) duration of flooding, (2) season in which
inundation occurs, (3) sedimentation rates, and (4) species present. As
with the tree vegetation, inundation during the growing season will result
in a die-back. Sedimentation tends to smother plant roots, and in many
cases, inhibits seeds from germinating.
The absence of vegetation within the drawdown zones precludes
much use by animal species. While drawdown is occurring, otters and
raccoons will feed on benthos organisms exposed by the receding waters
and some birds will utilize the drawdown zone for feeding.
Size of the new habitat is determined by topography of the lake
body and purpose of the lake. Topography determines the surface of habitat
formed by drawdown or inundation. Purpose determines the use(s) of the
waterbody which, in turn, dictates the degree of volume change.
Acreage of new habitat is calculated by (1) determining the
height of the drawdown pool, (2) planimetering the appropriate topographic
line, (3) multiplying this distance by the height difference to the flood-
pool, and (4) establishing acreage.
The relationship of the new habitat to the scenario of the lake
ecosystem cannot be generalized. Each reservoir should be evaluated
separately by comparing environmental survey data with monitored data.
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Nutrient Input to the Downstream Terrestrial Environment Will Decrease Due
to the Entrainment of Sediments Within the Impoundment -
Water flowing across agricultural lands, feedlots, forests, etc,
is the most important mechanism in the transport of soil particles, plant
residues, manure, and nutrients from the terrestrial environment to the
aquatic environment. Streams, creeks, and rivers carry these deposits to
other terrestrial areas and to the oceans.
The reservoir serves as a "sink" for sediments and nutrients
carried by the waterbody being impounded. As a result, a portion of the
input energy (nutrients, carbon and mineral soils, etc) normally received
by the downstream terrestrial habitat is now held by the reservoir (Ortolano
et al, 1973).
Definitive data on specific nutrients and on distance transported
downstream are not generally available. However, sediment load or degree
of sedimentation occurring within the reservoir is usually predicted in the
process of reservoir designs. These data can be used to estimate the degree
of nutrient entrapment. However, the magnitude of this phenomenon is site
specific and gross statements should not be made.
The following equation is used to predict sediment load:
vs - EQs
where V0 = volume of sediment storage per year
o
E = trap efficiency of reservoir
Q = volume of sediment which enters reservoir/year.
O
E = 1 - 1
1 + RC/W
icre-feet)
R ranges from .046 to 1.0 with mean value .1
2
where C/W = reservoirs capacity (acre-feet) to watershed area (m. )
or
E = 1
.012 + .0102 C/I
where C/I = reservoir capacity to annual inflow.
92
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The sediment inflow Q is estimated from sediment transport
studies or from actual sedimentation measurements from the waterbody to be
impounded.
Os = f (D, V, S, P,
-------
The area, depth, and volume of the pool can be determined
planimetrically as described above. In some reservoirs,
depending on purpose, size, location within the watershed, and discharge
regime, pool dimensions are rather constant; in others (characterized by
extensive water level fluctuations), dimensions are variable in time.
Due to impoundment, a stream reach becomes, to varying degrees,
a lake. Whereas both are aquatic habitats, their ecological characteristics
are different, predicated on different arrays of physical constraints.
Current is much more of a controlling and limiting factor in streams. Air-
water and land-water interfaces are more extensive in streams than lakes,
leading to more uniform gas tensions and a more open ecosystem with a
heterotrophic type of community metabolism.
Typically, compositional and functional aspects of stream and
lake communities are somewhat different. Species diversity per unit area
is usually higher in streams, due to the plethora of microhabitats available
for utilization. Food webs in most streams are based upon (and dependent
upon) continual input of allochthanous detritus (organic material from
outside the water body), whereas lacustrine food webs are more closed,
dependent instead on _in situ (primary) production of organic substrates.
Stream-dwelling organisms are generally more tolerant to thermal changes,
but less tolerant to gas tension changes, than are lake-inhabiting
organisms.
Due to these and other factors, the species composition and
community function of a stream ecosystem will change if the stream is
impounded. Some species will be excluded from the new ecosystem; others
will occur in the new ecosystem which were not present in the old one.
Evaluation of specific changes in species composition and community function
must be done on a case-by-case basis, due to the large number of geographic
and reservoir design variables involved. Some degree of prediction as to
the nature of the change is possible, if the following information is known.
(1) Species composition of the stream reach which will be
impounded
(2) Species composition of lakes which approximate the
characteristics of the impoundment-to-be
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(3) Physical changes which will occur due to impoundment
(sedimentation, retention time, stratification,
dissolved gas tensions, thermal regimes, etc)
(4) Tolerance of stream species to changes in physical
characteristics which will be elicited by the
impoundment-to-be
(5) Any intentional species additions (e.g., fish stocking)
to be included in the proposed action.
However, assessment of ecological change can only be accomplished ex post
facto by comparing results of postimpoundment surveys with preimpoundment
surveys. It should be remembered that postimpoundment characteristics will
change in time, and, therefore, establishment of a rigid benchmark for
survey periods is inappropriate.
The Stream Community Downstream of the Reservoir Outlet Will Change in an
Indeterminant Manner -
Impoundment invariably changes the downstream flow regimen. The
nature and extent of this alteration is a function of the discharge regime
of the dam, the location of the dam within the watershed, and the upstream
hydrological characteristics of the watershed. Alteration of the downstream
flow regimen should be evaluated as a part of any impoundment project; this
will involve the use of appropriate analytical techniques (see Leopold et al,
1964).
The effects of altered discharge regimens on downstream ecology
must be evaluated on a case-by-case basis, since many variables enter into
play. Historically, biologists involved in impoundment projects have
attempted to determine the minimum quantity and quality of water which will
"maintain" the stream resource. However, this approach has often led to
maintenance of a mere vestige of the former downstream aquatic ecosystem.
Discharge recommendations are often based on subjective judgment, without
due consideration for the requirements of the organisms involved. Partic-
ularly inappropriate is the process by which attempts have been made to
dignify judgmental decisions in connection with downstream flow regimens
95
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vis-a-vis numerical quantification. Judgmental decisions must suffice in
many cases but should not be disguised in a misleading form. Assumptions
that a given percentage of former flow is the fundamental governing factor
for maintenance of a given species or the stream's ecology as a whole are
especially tenuous.
Prediction of the consequences of downstream flow regimen altera-
tions requires a good deal of specific baseline information, and should be
regarded as tenuous until after-the-fact investigations are made. Informa-
tion required for evaluation of downstream impacts includes:
(1) Baseline information on the flow regimen downstream
of a proposed dam site
(2) Itemization of the nature and extent of flow regimen
changes which would be caused by construction and
operation of a dam of specified design and size
(3) Species composition (in time and space) of the down-
stream reach to be affected, to be investigated prior
to initiation of construction
(4) Location of special ecological features downstream
(e.g., spawning areas, migration corridors, point
source discharges)
(5) Determination of tolerance of (3) and (4) to changes
per (2).
The first four factors may be investigated prior to construction
and operation of an impoundment. However, the longer-term aspects of (4)
and (5), which are site specific, cannot be obtained from the literature
and must await after-the-fact interpretation and evaluation. However,
particular attention should be given before-the-fact to reservoirs proposed
for geographical areas which are (1) in reaches of watersheds utilized for
spawning by migratory organisms, (2) in reaches of watersheds which must be
traversed by migratory organisms to upstream/downstream spawning areas,
(3) in reaches of watersheds immediately upstream from coastal plain
estuaries and/or marshes, (4) in reaches of watersheds utilized by migratory
and/or resident waterfowl, and (5) in reaches of watersheds which are
utilized by rare or endangered species.
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TERRESTRIAL IMPACT ASSESSMENT CONSIDERATIONS
Little well-documented information on reservoir effects on
terrestrial lands is available. Two reasons for this are: (1) reservoirs
are permanent structures; thus, terrestrial lands which have been inundated
for long periods of time are not available for study, and (2) reservoirs
tend to be goal orientated; thus, some economic measure of effect (water for
irrigation, transport, etc) has, in the past, been used to quantify impact.
At present, however, environmental impacts are being considered in both the
macro- and microenvironmental vein, which necessitates evaluating a project
from both a site specific and regional viewpoint. The purpose of this
section is to discuss specific impacts documented in Tables 6 through 11
and discuss factors which are of particular importance in controlling the
nature and magnitude of these changes.
Inundation of Terrestrial Habitat
Inundation creates a catastrophic impact in that terrestrial
habitat is converted to aquatic habitat. Any terrestrial land use formerly
practiced on the inundated lands is, of course, no longer possible. Today,
land is usually classified by what it is being used for, not by what it
should be used for. Thus, few rules exist to guide the evaluator in making
decisions concerning magnitude of impact. However, several factors can be
considered which will enable one to make some estimates of environmental
impact.
(1) What is the present land use in the inundated area? Are
these lands considered "productive or marginal" in terms of food or fiber
production? The inundation of marginal land would not have the secondary
and tertiary effects that would result from inundation of productive farm
and timber lands (foods, fiber, payrolls, taxes, etc).
(2) What is the present land use in the reservoir "region"? In
many cases, the environmental effect of a reservoir is minimized when con-
sidering the region as a whole. The removal of terrestrial habitat by
inundation may create new habitat below the reservoir due to stream
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Stabilization. Land use may change from marginal food and fiber production
to recreational use. Power availability or flood control may open up new
lands for more intensive management.
(3) What effects will the reservoir have on recreation and
recreation-oriented industries? Evaluating these changes is not simple,
nor are there any rules of thumb. Again, the suggested method is to evalu-
ate effects as to (1) site specific and (2) regional. In many cases, local
people welcome the idea of flood control, a new power source, or a channel
to carry products to markets. However, the regional citizen, who uses
marginal lands for hunting or a river for boating, tends to view reservoirs
negatively.
(4) What effects will inundation have on the resident wildlife
population? Some possibilities to consider are (1) decrease (or increase)
in habitat diversity and carrying capacity, (2) displacement of wildlife
due to construction and/or lake usage, (3) dissection of habitat and habitat
isolation for animals with small home ranges, and (4) potential for migra-
tion routes being displaced or destroyed.
(5) Are there any rare or endangered species within the area to
be inundated? Points to be considered for investigation are (1) displace-
ment of local population, (2) increase or decrease in available habitat
and carrying capacity, (3) increase or decrease in accessibility for collec-
tors and hunters, and (4) potential for disturbance during construction.
These questions are only suggested as guidelines for developing
questions concerning specific projects. Potential or historically docu-
mented examples of reservoir impacts to inundated terrestrial habitat are
listed in Table 6.
Changes in the Land/Water Interface
Changes in the land/water interface, which is increased by reser-
voir creation, affect terrestrial habitats in two primary ways: changes
increase the potential area for recreational use and changes increase the
"edge effect" on terrestrial habitats.
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TABLE 6. POTENTIAL TERRESTRIAL BIOLOGICAL IMPACTS ASSOCIATED WITH
INUNDATION OF TERRESTRIAL HABITAT
Impact
Author(s)
Results in loss of productive lands including
floodplain.
Displaces natural wildlife populations.
Changes available riparian vegetation habitat,
Removes possible link in food chain of animals
such as black bear and bald eagle which depend
on migrating salmon for a critical-time food
supply.
Interrupts migration routes of animals.
Loss of spring and fall forage for elk, moose,
and deer.
Fluctuation results in large barren areas,
separates vegetation from water margin, and
opens new terrestrial habitat.
Forms localized marshes or swamps.
Increases aquatic growth at reservoir edges,
Results in damage by ice, debris, and fluctuating
water level limiting shoreline tree size.
Controls nuisance plant growth.
Blair, 1972
AED-Louisville, 1971
Bureau, 1972
TVA, 1972
AED-Huntington, 1972
Ortolano et al, 1973
AED-Savannah, 1972
Bureau, 1972
AED-Savannah, 1972
Ortolano et al, 1973
Symons, 1969
Arend, 1969
Hynes, 1970
U.S. Senate, 1960
Bureau, 1972
Jackson, 1966
Arend, 1969
Berkowitz, 1971
Laglear, 1971
California, 1970
Ortolano et al, 1973
Wistendahl and Lewis, 1972
Wistendahl and Lewis, 1972
California, 1970
Estes, 1972
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Lake surfaces provide access to land areas which were isolated
before reservoir construction. This ease of access presents problems which
are indirect results of reservoir formation. People may displace wildlife,
destroy plant life, and create erosion problems around lake shores. The
reviewer should ask himself: (1) are there any fragile plant or animal
populations subject to disruption from boating or lakeshore activities, and
(2) are there shoreline areas where human activity could result in erosion
problems? The "edge effect" (Odum 1970; Treshaw 1970) is the summation of
changes in the physical environment which result when the terrestrial canopy
is broken. This break results in increased radiation (sunlight) levels,
increased evapotranspiration rates, and furnishes a larger surface area
influenced by wind. The major consequence of these changes is that dominant
canopy habitat is replaced with edge habitat. Due to higher energy input
(solar radiation) and less competition for moisture (depending on topography),
edge communities are much more productive. Thus, carrying capacity for some
organisms (deer, raccoon, songbirds, rabbits) is actually increased.
When considering impacts due to edge effect, the reviewer should
consider such questions as
(1) What kind of "edge" will result from reservoir formation?
Narrow, deep lakes with fluctuating water levels are not conducive to good
"edge" habitat because small fluctuations in water levels result in habitat
destruction and erosion problems. Reservoirs with gentle slopes and rela-
tively stable water levels are conducive to good "edge" habitat formation.
(2) What type of recreational use will the lakeshore receive?
Heavy use by campers and "day users" can result in shoreline degradation
without proper management.
(3) What type of plant communities are expected to emerge along
the lake shore? Slope angle plays a dominant role in determining community
type and success. Wistendahl et al (1972), found that slopes above 20 per-
cent tended to erode rapidly, thus preventing plant establishment. On
slopes 20 percent and under, slight erosion took place and a potential for
natural revegetation was present.
(4) What is the potential for bank erosion and what will be the
effects? An eroding shoreline precludes the establishment of stable plant
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communities. The effect of erosion on aquatic systems is discussed in the
aquatic section below.
The formation of an "edge" habitat offers several possibilities
when considering environmental impacts. Examples of actual and potential
impacts are shown in Table 7. The questions and statements listed above
are only suggested guidelines for concepts that should be addressed.
Creation of a Drawdown Habitat
As water input seldom coincides with water output, changes in
reservoir volume occur; the magnitude of that change is dependent upon the
purpose(s) of the reservoir.
Terrestrial vegetation will not tolerate sustained inundation
particularly during the growing season. Inundation of the plant canopy blocks
gaseous exchange and photosynthesis in the leaf, whereas inundation of the
stem prevents CCL - ()„ exchange in the soil.
Several concepts should be addressed when considering the potential
for drawdown habitat formation.
(1) What is the intended use of the reservoir? Reservoirs
designed for channel maintenance or water supply seldom have large volume
changes; thus, the potential for creating a drawdown zone is slight. Flood
control reservoirs, however, do have seasonal fluctuations in water levels
large enough to form drawdown zones.
(2) What is the topography surrounding the lake? (Steep narrow-
sided lakes do not reflect the volume change that would occur in relatively
flat topography.
(3) What time of the year is drawdown anticipated? Many plant
species can withstand short periods of stem inundation (if excessive silta-
tion doesn't occur) during their dormant periods. However, inundation
during the growing season will result in death for most plants. Flooding
effect on southern forests is discussed by Broadfoot and Willinton (1973).
(4) What is the erosion potential during drawdown? Erosion
during drawdown occurs through two mechanisms: (1) rainfall and (2) wave
action. In flood control reservoirs, drawdown occurs just before the annual
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TABLE 7. POTENTIAL TERRESTRIAL BIOLOGICAL IMPACTS ASSOCIATED WITH A
CHANGE IN THE LAND/WATER INTERFACE
Impact
Author(s)
Changes available riparian vegetation habitat.
Stimulates growth of normally suppressed organisms,
possibly of detriment to others.
Interrupts migration routes of animals.
Increases land/water interface causing appearance
of new dominants and population complexes.
Fluctuation results in large barren areas,
separates vegetation from water margin, and opens
new terrestrial habitat.
Forms localized marshes or swamps.
Increases aquatic growth at reservoir edges.
Results in damage by ice, debris, and fluctuating
water level limiting shoreline tree size.
Restricts shoreline species often to willow and
silver maple which survive by frequent and
successful root sproutings.
Ortolano et al, 1973
Symons, 1969
Ortolano et al, 1973
U.S. Senate, 1960
Berkowitz, 1971
Jackson, 1966
Arend, 1969
Berkowitz, 1971
Laglear, 1971
California, 1970
Ortolano et al, 1973
Wistendahl and Lewis, 1972
Wistendahl and Lewis, 1972
Wistendahl and Lewis, 1972
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spring rains or snow melt occurs. During this time, wave action can severely
erode unprotected banks. Likewise, during the "fill-up" period, heavy rains
will erode unprotected banks.
Table 8 lists examples of potential site specific impacts due
to drawdown.
Decreased Nutrient Inputs to the Downstream
Terrestrial Environment
Nutrient input from stream or river overflow is an important
source of energy to the adjacent terrestrial habitat. However, when a dam
is built, the reservoir serves as a "sink" for sediments and nutrients
carried by the waterbody being impounded.
Several concepts should be considered in evaluating this impact.
How will the riparian habitat be affected? Stream overflow plays
several roles in determining the structure of riparian vegetation: it
furnishes nutrients, builds new land by sediment deposition, acts as a
selection mechanism in species composition, removes brush and other organic
debris, and maintains soil moisture levels.
Will a reduced nutrient input, along with stabilized flow, create
a new habitat? As stated in above, the overflow selects for certain
plants in that sediment deposition and periodic inundation establish a
unique environment suitable for certain species. When sediment deposition
and periodic overflow are curtailed, the plant environment changes. This
increases the potential for the introduction of new species, a situation
which could result in a new habitat type.
Examples of potential impacts resulting from a nutrient reduction
to the downstream terrestrial habitat are listed in Table 9.
AQUATIC IMPACT ASSESSMENT CONSIDERATIONS
A considerable amount of information on the ecology of reservoirs
is available. Limnologists throughout the world have been attracted to man-
made impoundments as outdoor laboratories. These impoundments represent
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TABLE 8. POTENTIAL TERRESTRIAL BIOLOGICAL IMPACTS ASSOCIATED WITH THE
CREATION OF A DRAWDOWN HABITAT
Impact
Author(s)
Changes available riparian vegetation habitat.
Stimulates shoreline erosion.
Fluctuation results in large barren areas,
separates vegetation from water margin, and
opens new terrestrial habitat.
Increases aquatic growth at reservoir edges.
Results in damage by ice, debris, and fluctuating
water level limiting shoreline tree size.
Restricts shoreline species often to willow and
silver maple which survive by frequent and
successful root sproutings.
Ortolano et al, 1973
Symons, 1969
Wistendahl and Lewis, 1972
Jackson, 1966
Arend, 1969
California, 1970
Ortolano et al, 1973
Wistendahl and Lewis, 1972
Wistendahl and Lewis, 1972
Wistendahl and Lewis, 1972
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TABLE 9. POTENTIAL TERRESTRIAL BIOLOGICAL IMPACTS ASSOCIATED WITH A
REDUCTION OF NUTRIENTS TO THE DOWNSTREAM TERRESTRIAL HABITAT
Impact
Author(s)
Reduces natural fertilization from flooding.
Changes available riparian vegetation habitat.
Stimulates growth of normally suppressed
organisms, possibly to the detriment of others,
Loss of spring and fall forage for elk, moose,
and deer.
Fluctuation results in large barren areas,
separates vegetation from water margin, and
opens new terrestrial habitat.
Increases aquatic growth at reservoir edges.
Ortolano et al, 1973
Ortolano et al, 1973
Symons, 1969
Ortolano et al, 1973
Wilson & Bossert, 1971
Bureau, 1972
Jackson, 1966
Arend, 1969
California, 1970
Ortolano et al, 1973
Wistendahl and Lewis, 1972
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recent lacustrine environments and offer the opportunity for understanding
limnological processes not necessarily typical of some of the natural lakes
of the world.
Reservoirs are constructed for one or more of a variety of
purposes, including flood control, hydroelectric power, water supply, and/or
recreation. Depending on the design of a reservoir and the environmental
circumstances in which it is constructed, the reservoir may or may not differ
appreciably from other lakes in the same geographical region. However,
reservoirs in all cases differ physically from the streams from which they
arise. These physical differences cause changes in the aquatic ecosystem
in the impounded reach of the stream and usually downstream from the dam
face as well. Some of the specific changes which occur are documented in
Tables 10 and 11.
This section categorizes various types of ecological changes
coincident with surface water impoundment and discusses factors which are of
particular importance in controlling the nature and extent of these changes.
Eutrophication
One of the fundamental "building blocks" of any living system is
carbon which is the major constituent of organic matter. Autotrophic
processes are those involving in situ production of organic matter. Allo-
trophic processes, on the other hand, involve influx of organic materials
into the system in question. In this context there are four general types
of lakes: dystrophic, mixotrophic, oligotrophic, and eutrophic. Dystrophic
lakes have large amounts of allotrophic organic material influx relative to
autotrophic production. Oligotrophic lakes and mixotrophic lakes are
characterized by small and large amounts of total organic matter production
and influx, respectively. Eutrophic lakes, on the other hand, are character-
ized by large amounts of autotrophic organic material production relative to
allotrophic influx.
The magnitude of autotrophy in a lake is a direct function of
primary productivity occurring therein, since photosynthesis is the chief
means by which organic material is initially produced. Whereas, there is
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TABLE 10. POTENTIAL AQUATIC BIOLOGICAL IMPACTS ASSOCIATED
WITH RESERVOIR POOL FORMATION
Impact
Author(s)
Requires several years for the system to attain
stability.
Increases detention time associated with reservoirs
increasing the extent of bacterial decay over a
given length of watercourse.
Reduces overall quality of the environment from
insufficient dissolved oxygen.
Increases rate of deoxygenation caused by decom-
position of inundated vegetation and/or organic
debris during first year.
Permits decomposition of the suspended load on a
reservoir bottom to develop a readily available
pool of minerals and nutrients causing water
quality deterioration.
Displaces natural river habitat and organisms.
Alters fish distribution and populations from
extensive enrichment.
Results in possible overpopulation with rough
fish.
Changes due to hypoliminal releases from lack of
dissolved oxygen.
Affects clam beds.
Alters success of freshwater mussel beds.
Stimulates growth of normally suppressed
organisms, possibly to detriment of others.
Creates a rich organic, but temporary, food
supply for insects larvae and detrial invertebrates,
Drops fertility levels after first few years
becoming more conducive to successful
reproduction to competitive species.
Reduction in cold water fisheries.
Hynes, 19 70
Kittrell and Furari, 1963
Ortolano et al, 1973
Anonymous, 1967
Jackson, 1966
Ortolano et al, 1973
Wistendahl and Lewis, 1972
Ortolano et al, 1973
Findlay, 1972
Jackson, 1966
Symons, 1969
Berkowitz, 1971
Tennessee Game, 1972
Hynes, 1970
Ortolano et al, 1973
Wilson & Bossert, 1971
California, 1971
Jackson, 1966
Jackson, 1966
TVA, 1972
Bureau, 1972
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TABLE 10 (Continued)
Imp act
Author(s)
Increased plankton and benthic habitats.
Interrupts migration routes of fishes.
Changes host parasite relationships of
organisms of the region.
Increased parasitism in bass resulting in
decline of sport fishing.
Increases aquatic growth at reservoir edges
Changes general fishing success.
Affects fish spawning (sediment, cover,
temperature).
Stimulates downward movement of species to
deeper, open waters.
Hynes, 1970
U.S. Senate, 1960
Becker, 1971
Waddy, 1966
Houghton, 1966
Becker, 1971
California, 1970
Ortolano et al, 1973
Wistendahl and Lewis, 1972
Estes, 1972
Jackson, 1966
Baren and Hewlett, 1971
Ortolano et al, 1973
Fraser, 1972a and b
Baren and Hewlett, 1971
Estes, 1972
Hynes, 1970
Jackson, 1966
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TABLE 11. POTENTIAL AQUATIC BIOLOGICAL IMPACTS ASSOCIATED
WITH ALTERATION OF DOWNSTREAM FLOW REGIMEN
Impact
Author(s)
Reduces overall quality of the environment from
insufficient dissolved oxygen.
Displaces natural river habitat and organisms.
Changes due to hypolimnial releases from lack of
dissolved oxygen.
Reduces natural fertilization from flooding.
Reduces flow of food downstream from lake
sedimentation.
Changes in thermal regime cause reduction of
benthic fauna downstream.
Reduces freshwater flowing flowing into estuaries
Alters success of freshwater mussel beds.
Stimulates growth of normally suppressed
organisms, possibly to detriment of others.
Modifies spawning areas downstream.
Increases natural hatchery success due to altered
flow variability.
May reduce cold water species populations from
decreased flow levels.
May benefit cold water species environment with
downstream water warmer in winter, cooler in
summer
Reduction in cold water fisheries.
Interrupts fish migration.
Ortolano et al, 1973
Anonymous, 1967
Wistendahl and Lewis, 1972
Symons, 1969
Ortolano et al, 1973
Findlay, 1972
Jackson, 1966
Lehmkuhl, 1972
Blair, 1972
Tennessee Game, 1972
Hynes, 1970
Ortolano et al, 1973
Wilson & Bossert, 1971
U.S. Senate, 1960
Ortolano et al, 1973
AED-Portland, 1971
U.S. Senate, 1960
Wirth, 1970
Symons, 1961
Ortolano et al, 1973
TVA, 1972
Bureau, 1972
Hynes, 1970
Arend, 1969
Major, 1972
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TABLE 11 (Continued)
Impact
Author(s)
Changes general fishing success,
Affects fish spawning (sediment, cover,
temperature).
Estes, 1972
Jackson, 1966
Baren and Hewlett, 1971
Ortolano et al, 1973
Fraser, 1972a and b
Baren and Hewlett, 1971
Estes, 1972
Hynes, 1970
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no definitive breakoff between primary productivity rate and trophic status,
Rhode (1969) suggests that there are loose-knit ranges that can be generally
considered as benchmarks. These are listed in Table 12.
TABLE 12. RELATIONSHIP BETWEEN TROPHIC STATUS AND
PRIMARY PRODUCTIVITY (RHODE, 1969)
Eutrophic
Primary Productivity Oligotrophic Natural Polluted
2
Mean growing Season rates 30-100 300-1000 1500-3000 mgC/M /day
Annual rates 7-25 75-250 350-700 gC/m2/year
Almost all lakes, whether natural or man made, undergo a natural
succession toward eutrophy. Various perturbations can increase the rate
at which a lake becomes eutrophic, the most important of which is nutrient
influx, particularly with regard to labile forms of phosphorus and/or
nitrogen.
As an aquatic ecosystem becomes more productive in response to
nutrient influx, a number of changes often occur. Water transparency de-
creases, oscillations of dissolved gas concentrations become greater,
producer and consumer biomasses increase, species diversity generally de-
creases, and mean weights of individuals comprising consumer populations
generally decrease. In dimictic (two turnover periods annually) and warm
monomictic (one turnover annually) lakes characteristic of the United States,
problems often result during periods of thermal stratification, particularly
in the hypolimnion. In extreme cases of hypolimnetic deoxygenation, water
quality deteriorates, anaerobic decomposition may produce odorous smells at
the lake's surface, and fish kills due to suffocation may occur.
Eutrophication problems are not unique to reservoirs, but surface
water impoundment usually presents a unique set of circumstances with respect
to eutrophication. Newly created reservoirs often undergo an initial stage
of relatively high rates of autochthanous production, due to nutrients
released from decomposing terrestrial vegetation and soils which have been
subjected to inundation. This case would not be true for a barren mountain
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valley subjected to impoundment, but is true for the majority of impound-
ments which inundate extensive amounts of terrestrial vegetation. Most
well-designed and appropriately located reservoirs become less eutrophic
after the first 3 or 4 years of their existence, as nutrients derived from
inundated vegetation are transported downstream of the dam face and hence
outside of the reservoir ecosystem. Many variables are involved, partic-
ularly the morphometry of the lake and its retention time. Lakes of
relatively low-mean depths and high-surface area/volume ratios generally
require more time for natural eutrophication abatement, as is the case for
lakes with long retention times. However, the most important set of
variables concerning the future trophic fate of an impoundment are those
influencing nutrient influx into the lake basin from other points within the
watershed.
In many situations where nutrient influx from within the watershed
is appreciable and continuous through time, a reservoir will generally tend
to become more eutrophic through time rather than clear up of its own
accord. This is because a reservoir tends to trap nutrients which formerly
passed down a free-flowing stream.
Presently, a considerable amount of controversy prevails as to
which types of plant growth nutrients are critical to the control of eutro-
phication in reservoirs. Generally, phosphorus appears to be a key limiting
nutrient, although nitrogen, carbon, and/or silicon may be in critical supply in
selected reservoirs. Thus, nutrient limiting factors must be evaluated on
a case-by-case basis.
Methods for forecasting the nature and extent of eutrophication
of newly constructed reservoirs are neither specific nor well developed.
However, a variety of factors should be taken into account in evaluating
this potential. These are outlined below, and requisite information should
be considered in reservoir planning procedures.
(1) What is the nature and extent of the vegetation in the
land area to be inundated? (Heavily fertilized soils
will produce more extensive initial phases of algal
growth than will barren or forested areas.)
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(2) What will the morphometry of the new lake basin be like?
(Lakes with high surface area/volume ratios have a
greater potential for eutrophication than deeper, steep-
sided ones.)
(3) What will the retention time (the reciprocal of "through-
put") of the impoundment be like? (Impoundments with
long retention times will require more time to clear up
after their inception than will impoundments with rapid
throughput.)
(4) Will the impoundment undergo thermal stratification on a
regular yearly basis? What will the duration of the
stable (thermocline present) stratified period be?
(Hypolimnetic water quality and fisheries may be suscep-
tible to deterioration under stratified conditions.)
(5) What is the nature of the general land use pattern in the
immediate vicinity of the impoundment? (High intensity
agricultural practices and/or feedlot operations may
contribute extensive and continual nutrient burdens to
the reservoir pool, thus accelerating eutrophication.)
(6) What is the nature of influent water quality from streams
entering the reservoir pool? (Large and continual
nutrient burdens may occur in the reservoir pool due to
sewage and/or industrial wastes. On the other hand, some
types of toxic industrial wastes may serve to inhibit
algal growth and thus act as a deterrent to eutrophica-
tion.)
(7) What types of eutrophication control measures are
included in the proposed action? (Artificial destratifi-
cation via aeration; chemical precipitation of phosphates
with aluminum sulphate, etc; and addition of copper
sulphate all serve to improve one or more aspects of
water quality, but may produce adverse effects as well,
e.g., reduction in fisheries and/or potability.)
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(8) Are there reservoirs in the general vicinity (preferably
the same watershed of a proposed reservoir in question)
which presently exist, such that comparative deduction
can be utilized? (Examination of the trophic status of
surface water impoundments under similar conditions may
provide valuable insight into the fate of a proposed
impoundment.)
(9) What is the primary use to which the impoundment will be
put? (Most reservoirs are in part justified as multi-
purpose, but are designed primarily to fulfill a partic-
ular purpose, e.g., flood control, hydroelectric, or
water supply. The implications of eutrophication with
respect to intended reservoir usage are substantially
different. The potentially adverse effects of eutro-
phication would be greatest in reservoirs intended for
water supply and would be of significance to recreational
usage, particularly sport fishing, as well.)
(10) Are there projected land use changes for the reservoir
area, once created, or upstream or major tributaries
which could have a significant future bearing on afore-
mentioned influential factors?
(11) What is the nature of the monitoring program designed to
assess the nature, extent, and effects of eutrophication
in the proposed reservoir? (A comprehensive monitoring
program will include provision for measurement of primary
productivity, phytoplankton associations, nutrient budgets
(N and P), hypolimnetic oxygen deficit, and sediment redox
potential. It will also include provision for detection of
appropriate indicator organisms, fish composition, fish
kills, and plankton blooms.)
These guidelines are suggested for use in a general manner in
order to evaluate the comprehensiveness of environmental reports and environ-
mental impact statements pertaining to proposed reservoir construction
operations, and subsequent significance of eutrophication factors. A good
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deal of technical literature pertaining to many aspects of eutrophication
is readily available and should be consulted in the event specific infor-
mation is desired for timely evaluation of environmental impact statements.
Comprehensive treatment of the subject of eutrophication under single cover
is provided by NAS (1969) and Vollenweider (1970a). Detailed information
on a variety of technical facets of eutrophication can be readily screened
via several bibliographic abstract sources; most useful are Vollenweider
(1970b) and the University of Wisconsin Water Resource Center's bimonthly
eutrophication abstracts (obtainable at no charge from UWWRC, 1324 West
Dayton, Madison, Wisconsin 53706).
Sedimentation
When a stream is impounded to form a reservoir, its longitudinal
profile is changed. Specifically, the profile is reduced in slope over a
localized reach of the stream channel. This typically results in profound
alteration of the substratum, both upstream and downstream of the dam face.
Upstream of the dam face a relatively quiescent pool replaces a more turbu-
lent flow regime. Since the ability of an aqueous system to carry in suspen-
sion particles of a given size range is directly related to the magnitude of
turbulent flow (e.g., measured in terms of Reynolds number), large portions
of suspended sediments settle out under quiescent conditions. When this
occurs in a newly created impoundment, changes in substratum characteristics
occur. Relatively small-sized particles cover the former stream substratum
consisting of larger sized particles.
The change in the physical characteristics of the substratum
underwrites extensive alteration in benthic composition. Species depending
upon running water for food supply and hard attachment surfaces for position
maintenance (e.g., attached algae, stoneflys, caddis flies, several species
of mayflies, etc) are replaced by organisms which typically live "in" the
substratum rather than "on" it (e.g., oligochate worms, dipteran larvae,
and rooted vegetation in littoral zones). Also, alteration of benthic
composition obviously affects species dependent on benthic organisms as a
food source, such as some species of fish and birds. Species diversity of
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the benthos of an impounded pool is usually substantially lower than in its
formerly unimpounded, free-flowing status.
The pattern of sedimentation in reservoirs is usually not uniform.
In situations where influent tributary flows are extensive, deltas typically
form at their mouths. In reservoirs where influent streams are relatively
sluggish, sediment deposition is usually maximal in the most quiescent
region(s) of the reservoir pool, oftentimes near the dam face itself.
Sedimentation patterns are greatly influenced by the morphometry of the
basin and the degree of water level fluctuation in the reservoir pool
(Borland, 1971).
Sedimentation rates are also extremely variable when considering
an array of reservoirs. Key variables are loading rates of washloads and
bedloads, particle size distributions of washloads and bedloads, morphometry
of the impoundment's basin, the retention time of the pool, and the nature
of the upstream watershed. Instances of rapid reservoir sedimentation and
factors underlying this phenomenon are discussed by Langbein and Hoyt
(1959) and Allen (1972).
Aggradation can also occur in both upstream tributaries and down-
stream from the reservoir due to altered flow regimes. Sediment islands
thus formed change portions of stream channels from aquatic to terrestrial
habitats. The resultant decrease in stream capacity may be sufficient to
cause flooding of adjacent terrestrial habitats on a regular basis. In
some cases, above-datum emergent deltas and islands may become vegetated
leading to further increase in size. In others, erosion of these deposi-
tory forms can lead to intermittent reductions in water quality in or down-
stream from the reservoir. In addition to sedimentation rates, sedimenta-
tion patterns can have significant effects on the ecology of a reservoir
and upstream and downstream areas. In reservoir planning and in the evalua-
tion of existing or proposed reservoir projects, various factors pertaining
to sedimentation rates and patterns should be considered:
(1) What is the nature of washload and bedload loading
rates into the impoundment? (High loading rates
should be regarded as having significant potential
for eliciting extensive sedimentation.)
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(2) What are the particle size distributions of the washload
and bedload, and how do they relate to turbulence for
suspension requirements? (Virtually all bedload from
influent tributaries will settle out in a reservoir.
Those fractions of the washload which are not clay-like
in constituency will also usually settle out. Extremely
small-sized particles such as clays will usually remain
in suspension for long periods of time even under
extremely quiescent conditions.)
(3) What fractions of the washload and bedload are organic
detrital material? (Heavy loading of detritus will pro-
mote extensive decomposition, will provide a food source
for detritovores, and will provide nutrients in most cases
for enhancement of algal growth. Lakes subjected to
appreciable detritus loading are usually characterized
by high benthic productivity in deeper regions of their
basins.)
(4) What is the nature of the bathymetry of the reservoir
pool at the time of its inception? (Initially, sedimen-
tation is most likely to be most extensive in deep holes,
protected (from wind) bays, at the dam face, and at the
mouths of influent streams if they are not sluggish
streams.)
(5) Are there natural lakes, reservoirs, or check dams up-
stream of the impoundment in question? (These will cause
sediment loading to be appreciably reduced in that they
themselves act as sediment traps.)
(6) What is the nature of the terrain and soils surrounding
the reservoir? (High topographic relief and/or absence
of well-rooted vegetation could lead to appreciable
erosion under periods of extensive rainfall, thus vastly
increasing sedimentation rates.)
(7) Will water level in the impoundment be constant or fluctu-
ating? (Extensive water level changes will tend to reduce
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overall sedimentation rates, but will cause sediments to
be deposited primarily at mouths of influent streams and
in the deeper portions of the lake. Fluctuating water
levels will also tend to inhibit the formation of littoral-
rooted vegetation which acts as a sediment trap due to
quiescent conditions which it produces.)
(8) What types of benthic organisms inhabit similar lakes in
the same region, particularly in the same watershed?
(Benthic species composition is oftentimes quite similar
in related and/or interconnected lakes.)
(9) What are the anticipated trophic characteristics of the
impoundment? (Eutrophication will elicit a reduction in
benthic species diversity in the substratum, particularly
during the summer months. Of those species remaining,
production and decomposition rates will be appreciably
higher than under oligotrophic conditions.)
(10) Are natural stream discharge regimes rather uniform?
Will discharge regimes from the impoundment be appreciably
reduced? (These factors will be important determinants
of upstream and/or downstream aggradation. Delta and
island formation will change portions of stream channels
from aquatic habitats to terrestrial habitats.)
(11) What is the nature of the monitoring program designed to
assess the nature, extent, and effects of sedimentation
in the reservoir? (A comprehensive monitoring program
will include provision for measurement of bathymetry,
benthos species composition, particle size distribution of
the deposited sediments, and sedimentation rates at
various locations within the reservoir pool.)
A substantial amount of technical literature pertaining to sedi-
mentation in reservoirs and its effects upon reservoir ecology is available.
In addition to the aforementioned guidelines, pertinent literature dealing
with specifics on sedimentation and its effects in reservoirs should be
consulted in order to render reliable evaluations of proposed or existing
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impoundment projects. Einstein (1968, 1972), Harrison (1953), Gottschalk
(1964), and Borland (1971) provide generalized information on determination
of reservoir sedimentation patterns and rates. Burris (1954), Pillion
(1967), Nursall (1952), Ozhegova (1962), Solokova (1963), and Peterson and
Fernando (1970) provide information on benthic colonization of reservoirs
which have had different sedimentation patterns. For those wishing or needing
to further pursue technical aspects of sedimentation and its ecological
effects, annotated bibliographies of domestic and foreign literature on
sedimentation should be consulted. These are updated periodically by, and
are available from, the U.S. Clearinghouse for Federal Scientific and
Technical Information, Washington, B.C.
Thermal Stratification
When a reach of a stream is impounded, a variety of physical changes
occurs, both directly and indirectly. One of the most important of these
changes involves alteration of the thermal regime of the new water body.
These alterations are brought about due to greater depth and reduction in
the surface area/volume ratio coincident with impoundment of a stream.
Many reservoirs exhibit a trait uncharacteristic of rivers from which they
were derived, that of thermal stratification during the summer months.
Thermal stratification results in the formation of two or more discreet
zones within the reservoir pool, each behaving in large part independently
of the other(s). Under stratified conditions, the "epilimnion" (top lake)
is relatively warm and well mixed due to wind and/or tributary-derived energy
and the "hypolimnion" (bottom lake) is relatively cold and stagnant. These
two portions of the reservoir are separated by a "thermocline" (zone of rapid
temperature decrease with respect to depth) which may be thick enough to
constitute a rather arbitrarily defined "metalimnion" or middle-lake. The
different stratas1 integrities are maintained by differences in density
attributable to differences in temperature. Hutchinson (1957) and Kittrel
(1965) provide detailed information on the mechanisms underlying and regu-
lating the nature and extent of thermal stratification. Discussion of
forecasting techniques for thermal stratification patterns in newly
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created impoundments is provided in the Water Quality section of this
report.
The significance of thermal stratification to reservoir ecology
is multifaceted; it provides an additional factor in habitat differentia-
tion, and it often provokes a variety of changes in physical and chemical
characteristics which in turn influence the ecological characteristics of
the reservoir. Among these, generally the most important factor is that
of the virtual isolation of the hypolimnion from surficial influences.
In its isolated condition, if oxygen demand of sediments or suspended
organics is extensive, dissolved oxygen concentrations in the hypolimnion
may be appreciably reduced. Under these conditions, species inhabiting the
hypolimnia of such lakes are limited to those which are tolerant of low
oxygen concentrations; species diversity usually decreases as dissolved
oxygen concentrations become low. In addition, reduced oxygen tension can
have profound effects on sediment chemistry and consequent cycling of
inorganic materials within the water column, many of which influence bio-
logical growth, especially nutrient releases which can contribute to
eutrophication. Stratification can also lead to influent waters forming
density currents at discrete levels within the lake. In summer time, these
usually take the form of surface density currents since influent waters are
generally warmer than those of the hypolimnion. Depending upon reservoirs
discharge design, this can be of importance in determining residence time
of incoming waters and consequently, the waste assimilative capacity of the
reservoir.
A variety of factors should be taken into account in evaluating
the nature and extent of thermal stratification in newly created or proposed
reservoirs and the implications of stratification to reservoir ecology.
These include
(1) Is nutrient loading such that the reservoir is likely
to become eutrophic on a long-term basis? (If so,
extensive oxygen depletion in the hypolimnion can be
anticipated during the period of stable stratification.)
(2) Is detritus loading such that large amounts of detrital
material will be present in the sediments? (This, too,
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may cause extensive hypolimnetic oxygen depletion
during stratified periods.)
(3) Are fish stocking plans for recreational purposes
consistent with anticipated hypolimnetic oxygen demands?
(Warm water species should be utilized in situations
where appreciable hypolimnetic oxygen depletion is
anticipated.)
(4) What is the proposed discharge regimen? (Reservoir
discharge from a deoxygenated hypolimnion will be cold
and low in dissolved oxygen concentration unless arti-
ficial aeration (e.g., raceways, turbine aerators, etc)
is employed. This will instigate a localized stress in
the stream ecosystem immediately downstream from the
dam face.)
(5) Are there industrial and/or agricultural discharges into
the reservoir via influent streams? If so, how do stream
temperatures compare with reservoir temperatures during
stratified periods? (This information is necessary in
order to evaluate the potential for density currents and
consequent reduced assimilative capacity of the
reservoir.)
(6) Does the monitoring program include provision for regular
measurement of temperature in the water column of the
lake? (This information can be used to determine the
duration of thermal stratification and the stability of
the reservoir during stratified periods; it can also be
used to indicate at what periods of the year vertical
mixing occurs.)
Comprehensive technical treatments of thermal stratification
and its significance in specific reservoirs are provided by Elder (1968)
and Symons (1969). These should be consulted for more detailed technical
information. Also see Knight (1965) and Krenkel, et al (1968), for
additional information pertaining to the effects of thermal stratification
on reservoir waste assimilative capacity and downstream water quality.
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Dissolved Oxygen
In addition to being one of the most important water quality
variables in reservoirs, dissolved oxygen levels and their fluctuations
play an exceedingly important role in determining the ecological character-
istics of reservoirs. Since dissolved oxygen concentrations in reservoirs
can vary from zero to supersaturation, a wide variety of microhabitats are
available to species which can capitalize on the immediate situation. For
example, game fish are typically intolerant of oxygen concentrations less
than 3-4 mg/-£. On the other hand, many types of rough fish (e.g., carp,
suckers, etc) apparently thrive under such conditions.
Dissolved oxygen concentrations in reservoirs vary both season-
ably and spatially, and are intimately related to many other factors
operating within the reservoir, such as temperature, nutrient loading,
organic loading, sediment chemistry, and degree and type of biological
activity. Dissolved oxygen enters a reservoir primarily by diffusion across
the air-water interface and by algal photosynthesis. Diffusion rates are
related to surface area, wind velocity, air temperature, water temperature,
and most important, turbulence (Fair et al, 1968). Photosynthetic produc-
tion rates are related to algal and/or submergent vegetation, standing crops,
temperature, light intensity, nutrients, and available carbon dioxide.
Dissolved oxygen is utilized by biological respiration and autoxidation of
both organic and inorganic materials. Resultant dissolved oxygen concen-
trations in the water column reflect the relative balance of production and
utilization processes.
Distribution of dissolved oxygen within a reservoir is influenced
by the mixing pattern of the reservoir pool. During periods of thermal
stratification, dissolved oxygen concentration in the hypolimnion is apt
to become quite low if hypolimnetic oxygen demand is high. This is of
important significance to hypolimnetic biological activity and sediment
chemistry. When dissolved oxygen concentrations decrease to near zero (to
the extent that the oxidation-reduction potential of the sediment surface
is negative), reducing conditions prevail. Insoluble oxidized states of
iron (Fe£03), Manganese (M^Oo), and Phosphorus (FePO,) are reduced,
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resulting in releases of soluble states of these algal growth nutrients,
thus further contributing to eutrophication.
Various factors should be considered in evaluating the potential
for adverse dissolved oxygen reduction in reservoirs. In addition to those
to be considered with regard to eutrophication potential (see above), the
following should be considered:
(1) What is the nature of present or anticipated loading
rates of organic materials into the reservoir? (All
of these will contribute to oxygen demand, in addition
to in situ respiration.)
(2) What is the predicted depth of the thermocline? (This
may determine the extent of the "usable" portion of
the impoundment during stratified periods.)
(3) Will existing vegetation and woody debris in the basin
be removed prior to filling? (This will reduce initial
oxygen demand.)
(4) Is the woody vegetation surrounding the reservoir
deciduous or coniferous? (Deciduous leaf litter can
contribute extensive oxygen demand on a long-term
basis.)
(5) What is the intended use of the reservoir? (Extensive
hypolimnetic oxygen demand can serve to reduce water
quality and limit fishery potential. Hence, reservoirs
planned for water supply and/or recreational fishing
would present intended use inadequacies in the event
of intensive oxygen demand.)
(6) What is the nature of the monitoring program designed
to determine dissolved oxygen concentrations in the
reservoir? (A comprehensive monitoring program
should include provision for regular measurement of
dissolved oxygen at the surface, middle, and bottom
of the water column and should include provision for
summer measurement of sediment redox potential and
limiting algal nutrients liberated from the sediments.)
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(7) What is the proposed downstream discharge regimen and
penstock location of the dam? (Hypolimnetic discharge,
if not aerated, can cause depleted dissolved oxygen
conccnetrations for a localized distance downstream.
This will result in exclusion of species intolerant
of low dissolved oxygen concentrations from this
reach of the stream.)
See Public Health Service (1965) and Symons (1969) for additional
technical information pertaining to the determination, influence, and
implications of dissolved oxygen concentrations in reservoirs and their
downstream discharges.
Coliform Bacteria
Not all members of the coliform group of gram-negative bacteria
are pathogenic. However, total coliform and fecal coliform concentrations
in waters are frequently employed as an indicator of pathogenic potential.
Appropriate Federal and/or state coliform standards must be complied with
in order that waterbody classification and allowed usage can be determined.
Coliforms are derived from a variety of sources, but generally the most
important source with respect to reservoir planning considerations is
sewage waste discharge.
As coliform bacteria enter streams along with sanitary wastes,
their concentrations initially increase downstream from their source(s)
due to population growth. Bacterial density becomes greatest a certain
distance downstream, and further downstream bacterial die-off exceeds
population growth, leading to a decline in coliform concentration. Die-
off patterns are sufficiently systematic that several mathematical formu-
lations are representative (Frost and Streeter, 1924, and Phelps, 1944),
but are influenced extensively by a variety of environmental factors.
Coliform growth rates are dependent on temperature and seasonal tempera-
ture regimes. The amount of rainfall and consequent surface runoff from
the watershed, as well as the nature of the surface soils and vegetation,
have a direct effect on coliform concentrations in recipient streams.
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Stream pH values substantially different from neutrality (either acid or
alkaline) can inhibit coliform growth. Die-off rates are typically greater
in highly productive systems characterized by appreciable formation of
organic material (Kittrel and Furfari, 1963).
The increased retention time of streams brought about by im-
poundment usually compresses the die-off curve, such that appreciable
reduction in coliform standing crops occur in relatively small areas. The
key variables to consider in evaluating the potential significance of
coliform bacteria in a proposed reservoir are
(1) What is the nature of coliform die-off in the reach
of the stream to be impounded? (Historic coliform
data are required and relationships between stream
discharge, season, temperature, and BOD determined.)
(2) What are the projected increases in sewage loading
in upstream tributaries in relation to time and
distance from the reservoir pool?
(3) Is anticipated thermal stratification in the reservoir
such that surface density currents will occur during
the summer? (This will serve to increase the area
in which a given magnitude of coliform die-off occurs.)
(4) Is the anticipated pH of the reservoir substantially
different than the neutral (< 6.3 or > 8.3)?
(Coliform die-off will be rapid and virtually complete
under these conditions.)
(5) What are present and projected patterns of BOD loading
into the impoundment reach of the stream? (If organic
loading rates are high, larger incoming populations of
coliforms will generally occur, but will die off
rapidly under periods of lengthened retention time.)
(6) What is the intended use of the reservoir? (High
concentrations of coliforms in the reservoir or
portions of the reservoir will interfere with its
direct use as a water supply and, if severe, could
restrict some recreational activities such as swimming.
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Homesite/campsite development along the waterfront
could act in concert with tributary coliform influx
in increasing coliform concentrations in localized
areas of the reservoir.)
(7) What is the nature of the monitoring program designed
to keep check on coliform levels in the reservoir?
(A comprehensive monitoring program should include
provision for regular determination of total coliform,
fecal coliform, and fecal streptococci concentrations
at appropriate sampling stations within the reservoir.)
A variety of technical literature can be consulted for further
information regarding coliform growth and die-off patterns, and how they
are influenced by different types of environmental conditions. Kittrell
and Kurfari (1963) discuss coliform bacteria growth and die-off in streams.
Vanderhoof (1965) and Houghton (1966) provide information on the effect
of surface water impoundment on coliform die-off patterns. APHA (1971)
presents various methods and their relative advantages and disadvantages
for measuring total coliform, fecal coliform, and fecal streptococci concen-
trations .
Fisheries
When a reservoir is created, the aquatic habitat of the impounded
stream changes in so many ways that most fish species which inhabited the
former stream do not remain in the reservoir. This is particularly true of
game fish species. Generally, the game fish fauna of reservoirs is derived
from immigration from other lakes in the watershed of the reservoir and/or
by initial or continual stocking from other regions.
Reservoirs are usually classified as "cold water" or "warm water"
with respect to potential fishery establishment. Cold water reservoirs are
those in which water temperatures are suitable for establishment and main-
tenance of salmonid populations. This generally requires that temperatures
in at least some portions of the reservoir remain below 60-65 F during the
summer months. This condition is usually characteristic of deeper reservoirs
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in mountainous regions. Warm water reservoirs constitute the remainder,
and the fish fauna is comprised of species tolerant of warmer temperatures.
The majority of reservoirs in the United States are of the warm water
variety. Stroud (1966) estimates that warm water species predominate in
about 85 percent of public impoundments. Large reservoirs which undergo
regular and appreciable thermal stratification can contain both warm water
and cold water species which are vertically segregated during stratified
periods.
Fishery development in both cold water and warm water reservoirs
tends to follow the same general pattern. Rapid population growth typically
occurs during a reservoir's initial fertility subsequent to impoundment.
However, game fish are frequently outcompeted by rough fish during initial
reservoir development periods. Game fish populations are also subject to
other types of stress characteristic of many reservoirs. In the event of
appreciable sedimentation rates and/or drawdown, spawning areas may be
destroyed. Hypolimnetic oxygen deficiency may be so extensive in eutrophic
reservoirs that most or all fish species are confined to the epilimnion
during stratified periods. Under these types of conditions a cold water
reservoir would be suitable only for warm water species.
In addition to affecting the fish fauna in the impoundment itself,
creation of a reservoir can have marked effects on downstream and migratory
fisheries, particularly anadromous species. Suitable ladders, locks,
artificial transport, or smolt rearing programs may be necessary in these
instances for migratory population maintenance.
The effects of reservoir discharges on downstream fisheries are
extremely variable depending on season, type of downstream fishery, water
temperature, dissolved gases, and method of discharge (e.g., location of
discharge ports, spillways, and nature of discharge flow regimen - see
Spence and Hynes, 1971, and Frey, 1963).
In addition, downstream effects may not be confined to locations
immediately downstream of a reservoir. In cases where the downstream
community is dependent on influx of detrital material for a food source,
surface water impoundment will markedly reduce fertility and fishery
potential. This is a particularly important factor in many types of highly
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productive coastal plain estuaries and lagoons (Copeland, 1966; Cooper and
Copeland, 1973).
In evaluating the ramifications of reservoir creation to upstream,
reservoir pool, and downstream fishery potential, a variety of factors
should be considered. These include
(1) What is the nature of the thermal regime of the reservoir
pool? (This will be an important determinant in terms
of the types of fish species which the reservoir pool
can support.)
(2) What is the anticipated trophic status of the reservoir?
(More fertile, eutrophic lakes will tend to support
larger standing crops of fish, but populations of which
are comprised of smaller individuals. Hypolimnetic
oxygen deficiencies associated with summertime conditions
in many eutrophic reservoirs will tend to limit the
fishery of the reservoir to a warm water variety.)
(3) Do migratory species presently utilize upstream (from
the dam face) portions of the watershed? (If so,
construction of the dam will require incorporation of
applicable mitigative measures into the reservoir plan.
These may include fish ladders, locks, artificial
transport, and/or artificial rearing programs.)
(4) Will natural colonization of the reservoir be the only
means by which game fish are introduced or will arti-
ficial stocking also be employed? (Game fish propaga-
tion will usually require some degree of artificial
stocking, particularly in the early years of the
reservoir's existence. Continual stocking may be
required if sedimentation prevents spawning success or
if angling pressure is heavy.)
(5) How does discharge water quality relate to near downstream
fishery requirements? (Downstream flow rates, discharges,
temperatures, and dissolved gas concentrations may all be
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deleterious to fish populations. Frey (1963) and Gordon
and Hall (1971) should be consulted for specific tech-
nical information on this subject.)
(6) How does the quantitative discharge regimen relate to
downstream fishery requirements? (Alteration of the
discharge regimen can affect flow rates, stream depth,
flooding, and sedimentation patterns. Spawning areas,
feeding areas, and food sources can be adversely
affected. Pfitzer (1954) and Fraser (1972) should be
consulted for additional technical information on this
subject.)
(7) To what extent is the downstream community(s) dependent
upon impact of allochthanous detritus for a food source?
(If the downstream community in question is heterotrophic
(P/R < 1), reduction in import of particulate organic
materials due to sedimentation will cause a shift to
autotrophy and at least an initial decrease in overall
productivity.)
A variety of technical literature can be consulted for additional
information on the effects of reservoirs on fisheries, both in the impound-
ments and downstream. Frey (1963), Gordon and Hall (1971), and Varley et al
(1971) discuss numerous examples of fisheries development in various im-
poundments. Frasure (1972), Alabaster (1970), Brett (1957), and Gordon
(1965) discuss the effects of impoundments on downstream fisheries due to
discharge regimen alterations.
MEASUREMENT CONSIDERATIONS
Ecological impacts entail a reference point from which change can
be measured. In order that a reference point be established, data must be
collected from the projected impact area. To facilitate evaluation of the
various methodologies that may be represented in impact statements, a variety
of measurement considerations are discussed, when applicable, as to (1) type
of data input, (2) input data needed, (3) assumptions of the technique, and
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(4) conditions under which a given technique would or would not be an
appropriate methodology.
Terrestrial Ecology Measurement Considerations
Census Data -
A census is a complete or sample count of animals over a speci-
fied area at a specific point in time. From these data estimates are made
on the total population being manipulated. The methods employed in
colleting the data and the form of the calculating formulae will depend
on the species, ,the season of the year, the habitat, the purpose of the
study, and on any other feature of the problem that might conceivably
influence the observations and the validity of the method. It is assumed
here that the worker is familiar with the ecology of the species and with
the relevant behavioral patterns and environmental features.
In general, the goal of population estimation should be twofold:
(1) to obtain the best possible estimates commensurate with the objectives
of the study and the time, resources, and personnel available, and (2)
make the estimation within determined limits of accuracy.
Auditory Index -
This technique uses the breeding, feeding, or nesting calls of
animals (particularly birds) to determine presence^ The investigator must
be competent in recognizing species by the sound produced.
Auditory activity is influenced by (1) time of day, (2) weather
conditions, and (3) season; thus, a specialist should design the sampling
program. When properly used, this methodology is excellent for estimating
occurrence and population densities.
Aerial Counts -
Aerial counts are used to estimate large mammal populations for
occurrence, size, and distribution. The observer is limited by (1) type
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of aircraft available, (2) season and time of count, (3) altitude, (4)
observer efficiency, and (5) pilot efficiency. A complete or random search
design may be used depending upon the species being counted and the degree
of accuracy needed. As individuals are sighted, a mark corresponding to
location is placed on a map. In this manner, distribution, occurrence,
and numbers of organisms are recorded. This technique has one major disad-
vantage in that estimates of population densities are consistently low.
Roadside Counts -
Roadside counts (can be called horseback, foot, or spotlight
counts depending upon mode of transportation and species counted) of
organisms are made by traveling a given distance with designated sampling
areas occurring along the way. For example, a count would be made at 1/2-
mile intervals for a total distance of 20 miles. Output is expressed as a
census index.
r • A N
Census index = —
M
where M = number of miles traveled
N = number of organisms seen.
Factors affecting this technique are
(1) Abundance
(2) Activity as affected by time of day, food avail-
ability, weather, and season
(3) Sex of animal or bird
(4) Condition of roadside cover.
This technique is valid when the areas traversed are representative of the
projected impact region.
Drive Counts -
Driving consists of moving the desired organisms past an observer.
Techniques are variable depending upon the size of the area and number of
personnel involved (aircraft have been used). The minimum requirement is
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that two observer teams be present. The drive continues until the driver
reaches the observers . Observers count or photograph organisms as they
pass.
This technique is limited in that only relative numbers are
acquired. Also, species being driven must be amenable to being pushed. It
works well in limited areas for large game but is useless for small game or
large areas.
Temporal Census -
The temporal census is analogous to the drive method. Here, the
spatial dimension is a point and the count is made of all animals passing
the point during some interval of time. Count is recorded by visual
observation or photograph.
This technique is good for migrating animals that use a definite
route.
Pellet Group Count -
Pellet counting entails selecting an adequate number of randomly
selected plots in which the feces of the organism being studied is counted.
These data are used mostly to determine presence or absence but can also be
used as an indices of population level or can be calibrated to give an
estimate of actual numbers.
Three assumptions are made for this method: (1) assume a specific
defecation rate, (2) assume a period (number of days or hours) over which
the groups of fecus have been deposited, and (3) assume that the observers
can correctly locate and identify the groups relevant to the population and
study period.
Application of the method is as follows :
where + = pellet groups per unit area
n = number of plots
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y
L,y = sum of groups counted overall in plots
a" = area of one plot
na1 = area of entire sample.
Defecation rate = 2 (dayS utilization Per acre (for the study period)
If the population is assumed constant, Z divided by the number of days in
the period (Assumption 2) yields the number of organisms per acre.
This technique is best suited for organisms that deficate recog-
nizable feces. It has been used successfully for deer during the winter
months in northern areas. Attempts to use the pellet index in the South-
east have been unsuccessful due to problems of differential decomposition
and disappearance of pellet groups.
Radiotelemetry -
Radiotelemetry describes the transmission of information from a
sensor element to a measuring system by means of a wireless radio link.
There are various types and methods being used from a sensor-recorder fixed,
to sensor movable with fixed recorder to no connection between sensor and
recorder. This technique is limited only by the sophistication of the
equipment employed. Factors that should be considered in setting up a
radiotelemeter study include the following:
(1) Reliability - suitability to task as to field
conditions or application
(2) Accuracy - included in design
(3) Range - required range for effective transmission
must be determined regarding terrain
(4) Duration - a matter of specification and design;
proportioned to capacity of the power source and
inversely proportional to the power of the
transmission
(5) Wavelength and interface - depending upon legal
restriction, interface, and operational considerations.
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Telemetry data are excellent for establishing home range, movements, and
migratory patterns.
Carrying Capacity -
Carrying capacity is the number of organisms a given area will
support. It can be expressed as K, the upper asymptote of the sigmoid
growth curve beyond which no major increase in numbers can occur:
dN = rN(R-N)
d+ K
where dN/dt = the rate of change in the number of organisms per time
at a particular instant
r = instantaneous coefficient of population growth; the
difference between the instantaneous specific birth
rate (b) and the specific instantaneous death rate (d)
r = b - d
K = carrying capacity (maximum population size).
K is a function of the size and quality of available habitat.
It can be estimated by establishing the major limiting factor inherent
within the habitat, i.e., habitat size, food availability, nesting or
breeding sites, predation, etc.
Carrying capacity is commonly used in wildlife management and
agricultural systems which have the data available for calculations. It
can be used to characterize a single species or a community depending upon
the complexity desired and the data available.
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Physiognomic Methods -
Physiognomic methods are used to present pictorial or graphic
descriptions of the vegetation under study (physiognomy is defined as the
outward appearance of a community). Species need not be identified when
using this method, as structure and form rather than names are used to
describe the vegetation (Figure 5 ). These symbols are then arranged
graphically (Figure 5 )•
This technique allows a presentation of the data to show structure
and form. However, it is preceeded by a floristic study which identifies
species present. It is useful to geographers and other nontaxonomists
concerned with the vegetation of the area.
Floristic Methods -
Floristic methods are used when more precise analyses are required,
By using these methods, the role of individual species in relation to the
"system" can be defined. Also, community groups can be identified. The
floristic method considers the following factors:
a. Frequency. Frequency expresses the percentage of sample
plots in which a given species occurs.
7=F = ^ x 100
N
F = frequency in percent
X = number of plots species occurred in
N = total number of plots.
It is a statistical idea which is obtained by studying a certain number of
sample plots as widely distributed throughout the study area as possible.
The frequency index is ordinarily a satisfactory method of expressing
occurrence within a community. The major limitation is that enough sample
plots must be sampled to give an accurate expression of frequency.
b. Density,, Density is the average number of individuals per
sampled area. A rough rule of thumb for selecting appropriate plot size is
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1. LIFE FORM
W O erecc woody plants
L I I climbing or decumbent
woody plants
E /\ epiphytes and crusts
H "\7 herbs
M L J bryoids
2. STRATIFICATION
1 more than 25 meters
2 10-25 meters
3 8—10 meters
4 2—8 meters
5 0.5-2 meters
6 0.1-0.5 merers
7 0.0 — 0.1 meters
*•
3. COVERAGE
b barren or very sparse
i interrupted,
discontinuous
p in patches, tufts,
clumps
c continuous
4. FUNCTION
d
deciduous or
ephemeral
semideciduous
evergreen
evergreen-succulent
or evergreen-leafless
5. LEAF SHAPE AND SIZE
o leafless
needle, spine, scale,
or subulate
membranous
sclerophyll
succulent or fungoid
x F "1 sclerophyll
FIGURE 5. THE SIX CATEGORIES OF CRITERIA TO BE APPLIED TO A
STRUCTURAL DESCRIPTION OF VEGETATION TYPES (Phillips, 1959)
136
-------
?
Wl
W2
W3
W6 W7
nLi b AEI
CHI1-2 AE2
1 | L3 1 — i ^4 y\E3
— 1 — 1 L5 AE4
riL6 AE5.r,
— 1 — 117 A
AE7
1
"2
'3
4
5
6
7
H4
L_i
H5
116
n
(1
P ^
v-x ' ^7
5 (
>* ^\
r
a
i)
H7 M6
M7
A graphic representation of all the symbols
combining criteria 1 (life form) and 2 (stratification or
height class) of Figured, and a series of crown out-
lines for tall woody types (W 1,2,3), which can fit the
periir:;cr cf ths syn.bot? in A. a is an average globular
crown tree, such as Quercus alba', examples of tlio
others are as follows: b, Nothofagus clifforlioir/cs;
c, many tropical rainforest trees; d, Araucaria angusti-
folia, and many palms; e, spruces, firs, many other
conifers; /, Pinus ponderosa, P. pinaster, Hex canari-
ensis; g.Juniperus virginiana, Cupressus sempervirens;
h, Populus itigra var. italica.
FIGURE 6.
SYMBOLS FOR STRUCTURAL DESCRIPTIONS OF VEGETATIVE TYPE (Phillips, 1959)
137
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(1) Low vegetation, 1 sq. meter
(2) Medium vegetation, 4 sq. meters
(3) Trees, 10 sq. meters.
As many sample plots as needed to adequately cover the study area
should be sampled.
The species within each sample plot are counted. Then, the total
number of each species is divided by the total sample area.
_ total number of individuals
total sample area
where d = individuals per square meter.
c. Cover. Cover is a term generally used to indicate the area
occupied by a species and is usually a measure of the area covered by the
crown or stem (basal area). It can represent percent ground cover per unit
area and is another indicator of dominance.
Data needed for these calculations are (1) fixed sample plots of
a determined size and (2) field personnel trained in analytical method-
ologies and taxonomy. Data output is exceptionally good. Vegetation maps
can be prepared, some indication of community structure is achieved, domi-
nant organisms are identified, and a good estimate of standing crop can be
made.
d. Succession (Forests). These techniques are used to evaluate
forest types. The relative numbers of species (frequency) and age of
species (calculated from increment cores taken from trees) are used to
establish a time frame for species introduction into the sample area. The
data are used to establish the age of and type of community.
Usually, samples are taken along a transect which traverses several
environmental gradients to furnish a holistic view of the project area.
Then, using the available literature and professional judgment, successional
series are established in time and space.
e. Site Index. Site index is defined as the height reached by
a species stand at a selected age. It involves measuring the height and
age of representative trees within a given area. The index suggests the
138
-------
"growth potential" of the site, i.e., the culmination of the abiotic factors
influencing growth. It is used to develop productivity estimates (logs per
unit time).
Site index is arbitrary at best but does allow a relatively quick
evaluation of the potential for a site to produce timber.
f. Productivity (Net).
Harvest method - In situations where a specific species is con-
cerned or in plant systems where herbivore consumption is negligible,
harvest data can be used as a measure of net productivity.
To calculate, biomass per unit area is collected, dried, weighed
and expressed as dry weight per unit area. This method is used for agri-
cultural crops, natural grasses and vegetation, and for forest trees being
cut for commercial consumption.
The data are limited in that only net productivity is measured.
If samples are not taken periodically throughout the growing season, some
plant species may not be included due to a short life cycle. Also, herbi-
vore consumption may be occurring which could (if the amount consumed is
large) reduce the accuracy of the data.
Basic method for estimating net plant productivity:
BI = Biomass plant community at time t
B = Biomass same community t_(= t + At)
<4B = B - B = Biomass change during t - t«
L = Plant losses by death and shedding during t^ - t^
G = Plant losses by consumer organisms as herbivorous
animals, parasitic plants, etc, durg. t.. - t
Pn = Net production by community during t1 - t
Measuring (or estimating) £B, L & G we calculate Pn
Pn = LB + L + G.
Carbon Dioxide Methods - This method equates CCL uptake to photo-
synthetic rates, thus producing a measure of productivity. As with the
harvest method, productivity can be calculated for a single organism,
species, or community.
139
-------
Two measurement variations are employed: (1) enclosure and (2)
aerodynamic. The enclosure method necessitates physically enclosing a tree
or community in a C0_ impermeable container. Air is pumped in through a
monitor where CO^ content is continually measured. The relationship of the
CO,, intake to C0_ production (light versus dark) is expressed as produc-
tivity. The enclosure method is limited by cost, complexity of the enclos-
ure, and plant response to the "artificial" environment.
The aerodynamic method utilizes periodic measurements of the
vertical CO- gradient occurs an open forest or vegetation system. The only
modification to the environment is a pole or mast which holds the C0~
census. However, correction coefficients for the mass movement of air and
for C0~ input from the soil determine the accuracy of the technique. It
has been used most in crop or grassland situations.
Aquatic Ecology Measurement Considerations
Composition -
The collection and identification of organisms within a project
area are necessary in order to establish which organisms are present.
Collection may be accomplished by one or more of a variety of techniques,
some of which are more applicable in some situations than others. Identi-
fication of organisms collected may be accomplished by the use of appropri-
ate taxonomic keys. Appropriate reference materials for sampling and
identification methodologies include Welch (1964), APHA (1973), Pennak
(1959), and Edmondson (1965). The information to be derived is of a quali-
tative instead of quantitative nature, and is used to generate species
accounts (lists) for a defined area.
Abundance -
Estimates of the relative abundance of different species within
a defined area require the use of quantitative techniques, which give
information in terms of weight (biomass) or numbers (abundance/density) of
140
-------
organisms of a specific type per unit area or volume. Many techniques are
used in this regard; fundamentally, they all are designed to register,
directly or indirectly, the size (aerial or volumetric) of the portion of
the environment which is sampled and organisms which are present therein.
The efficiency of sampling processes must also be considered. The applica-
bility of specific techniques to the attainment of specific information is
a matter of professional judgment, with due consideration given to accuracy,
assumptions involved, and sampling intensity which is required. The plethora
of techniques (or modifications thereof) which are used for estimation of
abundance precludes an itemization of them, particularly since new ones are
developed and brought on-line at a rapid pace. The most complete array of
newer techniques used is presented in journals such as Limnology and Ocean-
ography, Transactions of the American Fisheries Society, and other appro-
priate journals. Many classic (but often outmoded) ones are discussed in
Welch (1964) and APHA (1973). A reliable approach designed for assessment
of the reliability of the use of a specific technique in a specific situa-
tion would include
(1) Documentation (from the investigator) of the specific
technique, and the basis for its selection, including
identification of literature pertaining to the
specific technique utilized and other techniques which
could have been used
(2) Consultation with expert professional per reliability
of information supplied in (1)
(3) Evaluation (by reviewer) of information gained in (1)
and (2).
Temporal Change -
Measurements taken at one instant in time are not necessarily
applicable to all time frames. Seasonal sampling should be emphasized,
and continuous monitoring programs of key organisms should extend well into
the future (post-reservoir construction) if a true assessment of impacts is
to be gained.
141
-------
Short-term temporal factors also play an important role in the
significance of composition and relative abundance of species within a
community. An organism's relative abundance is not necessarily indicative
of its importance in the food web of a community. Productivity of the
species' population also must be considered in determining an organism's
significance as a material and energy sink and/or source. There are
numerous techniques for determining rates-of-change of species' populations
and/or food web components (sometimes assemblages of numerous species
populations); specific techniques are applicable to specific situations and
circumstances. As in the case of techniques for determining standing crops,
some latitude of choice is generally available, and final choice is usually
a matter of professional judgment. A good deal of background information
or a variety of productivity techniques is presented in reviews by Vollenweider
(1969) (algae and periphyton), Edmondson and Winberg (1971) (secondary
producers), and Ricker (1971) (fish).
142
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REFERENCES
A.E.D., Huntington, W. Va. 1972. Final environmental impact statement:
Yatesville Lake, Elaine Creek, Big Sandy River Basin, Ky. NTIS PB-200-941-F.
A.E.D., Savannah, Ga. 1972. Draft environmental impact statement: Curry
Creek Reservoir, North Oconee River, Ga. NTIS EIS-Ga-72-4577-D.
Alabaster, J.F. 1970. River flow and upstream movement and catch of
migratory salmonids. J. Fish. Biol. 2:1-13.
Allen, R.N. 1972. The Anchicays Hydroelectric Project in Columbia: design
and sedimentation problems. In The Careless Technology, Ecology and
International Development, M.T. Farvar and J.P. Milton, eds., Nat. Hist.
Press, Garden City, N.Y., 342 pp.
American Public Health Association. 1971. Standard methods for the examina-
tion of water and wastewater, 13th edition. American Public Health
Association, N.Y. 874 pp.
1973. Standard methods for the examination of water and waste-
water. American Public Health Association, N.Y. 769 pp.
Anonymous. 1967. Lake Erie: dying but not dead. Env. Science and
Technology. 1:212.
Arend, P.H. 1972. The impact of the Dos Rios Dam on the wildlife ecology
of the Eel River, California. In The Effects of Middle Fork Eel River
Development on Wildlife 'Resources, California Dept. of Fish and Game,
Sacramento, California.
Army Engineer Dist., Louisville, Ky. 1971. Draft environmental impact
statement: Lincoln Lake, Embarras River, 111. NTIS PB-198-998-D.
Army Engineer Dist., Portland, Ore. 1971. Draft environmental impact
statement: Applegate Lake, Rogue River Basin, Ore. NTIS PB-200-792-D.
Atkinson-Wilber, G.L. 1966. General discussion. In Man-Made Lakes,
R.H. Lowe-McConnell, ed., Academic Press, N.Y., p 201.
Bardach, J.E. 1966. Some ecological implications of Mekong River Develop-
ment plans. In The Careless Technology, Ecology and International
Development, M.T. Farvar and J.P. Milton, eds., Nat. Hist. Press, Garden
City, N.Y., p 236.
143
-------
Baren, C.F. and H.A. Hewlett. 1971. Delaware River Basin Commission—
pumped storage and spawning of fish. In Pumped Storage Development and
Its Environmental Effects, G.M. Karad, et al, eds., Amer. Water Resource
Assoc., Urbana, 111.
Bates, J.J. 1970. Ohio Mussel Fisheries Investigation. U.S. Bureau of
Commercial Fisheries, Final Report—Part I.
Beck, D.E. and K.B. Trousdell. 1973. Site index: accuracy of prediction.
USDA Forest Service Research Paper SE-108, Asheville, N.C.
Becker, D.A. 1971. Impoundment effects on water quality as reflected in
parasitism of reservoirs basses. NTIS PB-20ID-826.
Bennett, D.H. and J.W. Gibbons. 1972. Food of largemouth bass (Micropterus
Salmoides) from a South Carolina reservoir receiving heated effluent.
Amer. Fisheries Soc. Trans. 101(4):650.
Blair, W.F. 1972. Ecological aspects. In Water, Man and Nature, a
Symposium Concerning the Ecological Impact of Water Resources Development,
U.S. Government Printing Office, Washington, D.C.
Borland, W.M. 1971. Reservoir sedimentation. In River Mechanics,
H.W. Shen, ed., H.W. Shen, Fort Collins, Colorado, Chapter 29.
Born, S.M. and D.A. Stephenson. 1973. Water management for shoreline
erosion control on the Chippewa Flowage. J. of Soil and Water Conservation
28(2):83.
Brett, J.R. 1957. Salmon research and hydro-electric power development.
Bull. Fish. Res. Bd. Can. 114:1-26.
Bureau of Reclamation, Salt Lake City, Utah, Region 4. 1972. Draft
environmental impact statement: China Meadows Dam and Reservoir, Lyman
Project, Wyoming. NTIS PB-205-581-D.
Burris, W.E. 1954. The bottom fauna development of a newly constructed
pond in central Oklahoma. Proc. Okla. Acad. Sci. 33:129-136.
Buss, 1.0. 1970. Effects of water impoundments on reproduction and
population number of waterfowl on the Snake River, Washington. NTIS
PB-194-456.
California Dept. of Fish and Game. 1970. Preliminary report on impact of
Trinity River water development on fish and wildlife resources. Environ-
mental Services Administrative Report 70-2, Sacramento, California.
California Dept. of Fish and Game. 1971. Report on the status of reservoir
research. Sacramento, California.
144
-------
Cooper, D.C. and B.J. Copeland. 1973. Responses of continuous-series
estuarine microecosystems to point-source input variations. Ecol. Monogr.
43:213-236.
Copeland, B.J. 1966. Effects of decreased river flow on estuarine ecology.
J. Wat. Poll. Cont. Fed. 38(11):1831-1839.
Curtis, J.T. and R.P. Mclntosh. 1950. The interrelations of certain
analytic and synthetic phytosociological characters. Ecology 31:434.
Edmondson, W.T., ed. 1959. Fresh water biology. John Wiley and Sons, Inc.
N.Y., London.
1964. Fresh water biology. John Wiley and Sons, Inc., N.Y. 248 pp,
and G.G. Winberg. 1971. A manual on methods of assessment of
secondary productivity in fresh waters. IBP Handbook No. 17, Blackwell,
Oxford, 358 pp.
Einstein, H.A. 1968. Deposition of suspended particles in a gravel bed.
Hydr. Div. Proc. Amer. Soc. Civil Eng.
1972. Sedimentation. In River Ecology and Man, R.T. Oglesby,
ed., Academic Press, N.Y. 465 pp.
Elder, R.A. 1968. Proceedings of the specialty conference on current
research into the effects of reservoirs on water quality. Tech. Report
No. 17, Dept. of Env. and Water Resources Engin., Vanderbilt Univ.,
Nashville, Tenn.
Estes, R.D. 1972. Ecological impact of fluctuating water levels in
reservoirs. In Ecological Impact of Water Resource Development: A
Technical Session of the Symposium, Water, Man and Nature, Bureau of
Reclamation, Denver, Colorado, p 7.
Fair, G., J. Geyer, and D.A. Okun. 1968. Water and wastewater engineering.
John Wiley and Sons, Inc., N.Y., Vol. 2.
Farvar, M.T. and J.P. Milton, eds. 1972. The careless technology, ecology
and international development. Nat. Hist. Press, Garden City, N.Y.
Pillion, D.B. 1967. The abundance and distribution of benthic fauna of
three mountain reservoirs on the Kananaskis River in Alberta. J. Appl.
Ecol. 4:1-11.
Findlay, J.D. 1972. North Coast Project, Eel River Division, English Ridge
Unit, California. U.S. Bureau of Sport Fisheries and Wildlife.
Frey, D.G. 1963. Limnology in North America. University of Wisconsin
Press, Madison, Wisconsin, 734 pp.
145
-------
Fraser, J.C. 1972. Regulated stream discharge for fish and other aquatic
resources—an annotated bibliography. RAO Fisheries Technical Paper 112.
Frost, W.H. and H.W. Streeter. 1924. Publ. Health Bull. 143, Washington
State Public Health Service, Washington.
Fullner, R.W. 1969. A comparison of macroinvertebrates collected by basket
and modified multiple-plate samplers. J. Wat. Poll. Contr. Fed. 43(3):494.
Gill, D.A. 1971. Damming the Mackenzie: a theoretical assessment of the
long-term influence of river impoundment on the ecology of the Mackenzie
River Delta. Proceedings of the Peace-Athabasca Delta Symposium,
Edmonton, Canada.
Gordon, R.N. 1965. Fisheries problems associated with hydroelectric power
development. Can. Fish. Cult. 35:17-36.
Gottshalk, L.C. 1964. Reservoir sedimentation. In Handbook of Applied
Hydrology, V.T. Chow, ed., McGraw-Hill, N.Y., Section 17.
Hall, G.E. 1971. Reservoir fisheries and limnology. Amer. Fish. Soc.
Spec. Publ. 8, 511 pp.
Hamilton, J.D. 1961. The effect of sand-pit washings on a stream fauna.
Verb. int. Verein. theor. angnes. Limnol. 14:435-39.
Harrison, A.S. 1953. Deposition at the heads of reservoirs. Proc. Iowa
Hydr. Conf. No. 5, pp 199-226.
Hem, J.D. 1965. Discussion of mineral quality control through streamflow
regulation. In Symposium on Streamflow Regulation for Water Quality
Control, Public Health Service Publ. No. 999-WP-30, 420 pp.
Houghton, G.U. 1966. Maintaining the safety and quality of water supplies.
In Man-Made Lakes, Academic Press, N.Y.
Howard, R.G. 1972. Reservoir destratification improves water quality.
Reclamation Era 58(1):6.
Hubbs, C. 1972. Some thermal consequences of environmental manipulations
of water. Biol. Cons. 4(3):185.
Hutchinson, G.E. 1957. A treatise on limnology. Vol. 1. Geography,
Physics, and Chemistry, John Wiley and Sons, Inc., N.Y. 1015 pp.
Hynes, H.B.N. 1970. The ecology of running waters. Published in Great
Britain, Bungay, Suffolk.
Jackson, P.B.N. 1966. The establishment of fisheries in man-made lakes
in the tropics. In Man-Made Lakes, Academic Press, N.Y., p 53.
146
-------
Jobin, W.R. 1973. Environmental control of Bilharzia snails in small
reservoirs. J. Irrigation Drainage Div. , Amer. Soc. Civil Engin. 99(3):365.
Kittrell, F.W. 1965. Thermal stratification in reservoirs. In Symposium
on Streamflow Regulation for Quality Control, Public Health Service Publ.
No. 999-WP-30, 420 pp.
and S.A. Furfari. 1963. Observations of coliform bacteria in
streams. J. Wat. Poll. Contr. Fed. 35(11):1361-1385.
Knight, W.E. 1965. Improvement of the quality of reservoir discharges
through control of discharge elevation. In Symposium on Streamflow
Regulation for Quality Control, Public Health Service Publ. No.
999-WP-30, 420 pp.
Krenkel, P.A. et al. 1968. The influence of impoundment on waste
assimilative capacity. In Proceedings of the Specialty Conference on
Current Research into the Effects of Reservoirs on Water Quality, Tech.
Report 17, Dept. of Env. and Water Resources Engin., Vanderbilt Univ.,
Nashville, Tenn.
Lagler, K.F. 1969. Freshwater fishery biology. Wm. C. Brown Co.
Publishers, Dubuque, Iowa.
1971. Ecological effects of hydroelectric dams. In Power
Generation and Environmental Change, D.A. Berkowitz and A.M. Squires,
eds., MIT Press, Cambridge, Mass, p 133.
Langbein, W.B. and G.B. Hoyt. 1959. Water facts for the nation's future.
Ronand, N.Y.
Lehmkuhl, D.M. 1972. Change in thermal regime as a cause of reduction
of benthic fauna downstream of a reservoir. J. Fish. Res. Bd. Canada
29:1329-1332.
Lennon, R.E., and R.S. Parker. 1955. Electric shocker developments on
southeastern trout waters. Trans. Amer. Fish. Soc. 85:234-40.
Leopold, L.B. et al. 1964. Fluvial processes in geomorphology. Freeman,
San Francisco, 284 pp.
Lewontin, R.C. 1969. The meaning of stability. In Diversity and Stability
in Ecological Systems, Brookhaven Symposia in Biology No. 22, Upton, N.Y.
Brookhaven Nat. Lab.
Mackenthum, K.M. et al. 1964. Limnological aspects of recreational lakes.
HEW, Public Health Service Publ. No. 1167, Washington, D.C.
Major, R.L. and G.J. Paulik. 1972. Effect of encroachment of Wanapum
Dam Reservoir on fish passage over Rock Island Dam. Fishery Bulletin
70(1):125, NTIS COM-72-50251-01-13.
147
-------
National Academy of Sciences. 1969. Eutrophication: causes, consequences,
correctives. International Symposium on Eutrophication, Washington, D.C.
Neel, J.K. 1963. Impact of Reservoirs. In Limnology of North America,
D.G. Frey, ed., Madison, Wisconsin, pp. 575-93, 447, 449.
Newbould, P.J. 1967. Methods for estimating the primary production of
forests. IBP Handbook No. 2, Blackwell Sci. Publ, Oxford, Great Britain.
Nielsen, E. 1973. Coastal erosion in the Nile Delta. In Nature and
Resources, UNESCO, 9(1):10.
Nursall, J.R. 1952. The early development of a bottom fauna in a new power
reservoir in the Rocky Mountains of Alberta. Can. J. Zool. 30:387-409.
O'Connell, T.R. and R.S. Campbell. 1953. The benthos of the Black River
and Clearwater Lake, Missouri. Univ. Mo. Stud. 26, 2:25-41, 208, 211, 447.
Ortolano, L., ed. 1973. Analyzing the environmental impacts of water
projects. U.S. Army Engineer Institute for Water Resources, NTIS DACW
31-71-C-0127.
D.J. Ringel, and J.R. Jones. 1973. Ch. 5 environmental impacts
associated with reservoir projects. In L. Ortolano, ed., Analyzing the
Environmental Impacts of Water Projects, U.S. Army Engineer Institute for
Water Resources, NTIS DACW 31-71-C-0127.
Ozkegova, V.E. 1962. Facts related to the hydrobiological characteristics
of the Kairak-Kumsk Reservoir during the first year of its existence.
Tr. Zon. Sov. Po Tipol. i Biol. Rib. Ispol. Vrutr. Vod. Yuzhn. Zony
SSSR:172-177.
Patterson, C.G. and C.H. Fernando. 1970. Benthic fauna colonization of a
new reservoir with particular reference to the Chironomidae. J. Fish. Res,
Bd. Canada, 27:213-232.
Pennek, P. 1953. Freshwater invertebrates of the United States, Ronald,
N.Y., 769 pp.
Petrides, G.A., F.B. Golley, and I.L. Brisbin. 1968. Energy flow and
secondary productivity. In F.B. Golley and H.K. Buechner, eds., A
Practical Guide to the Study of the Productivity of Large Herbivores,
Blackwell Sci. Publ., Oxford, Great Britain, IBP Handbook No. 7.
Petrusewicz, K. and A. Macfayden. 1970. Productivity of terrestrial
animals; principles and methods. F.A. Davis Co., Philadelphia, IBP
Handbook No. 13.
Pfitzer, D.W. 1954. Investigations of waters below storage reservoirs in
Tennessee. Trans. No. Amer. Wild. Conf., 19:271-282.
148
-------
Phelps, E.B. 1944. Stream sanitation. John Wiley and Sons, Inc., N.Y.
Phillips, E.A. 1959. Methods of vegetation study. Holt, Rlnehart &
Winston, Inc., N.Y.
Pinnak, R.W. 1953. Fresh-water invertebrates of the U.S. The Ronald
Press Co., N.Y.
Public Health Service. 1965. Symposium on streamflow regulation for
quality control. Public Health Service Publ. No. 999-WP-30, 420 pp.
Ralston, C.W. 1964. Evaluation of forest site productivity. Intrnl.
Rev. of Forestry Research, 1:171.
Reid, G.K. 1961. Ecology of inland waters. Rheinhold, N.Y.
Rhode, W. 1969. Crystallization of eutrophication concepts in northern
Europe. In Eutrophication: Causes, Consequences, Correctives, NAS,
Washington, 661 pp.
Ricker, W.E. 1971. Methods for assessment of fish production in fresh
waters. IBP Handbook No. 3, Blackwell, Oxford, 326 pp.
Ruttner, F. 1963. Fundamentals of limnology. Univ. of Toronto Press,
Toronto, Canada.
Sakolova, N.I. 1963. The benthic fauna of the Matbaisk Reservoir during
the first year of its existence. Uch. i. Mozh. Vod. Giero. Biol. Pod.
Fak. MGU Mosk Univ. pp 355-374.
Spence, J.A. and H.B.N. Hynes. 1971. Differences in fish populations
upstream and downstream of a mainstream impoundment. J. Fish. Res. Bd.
Canada, 28:45-46.
Stroud, R.J. 1966. Comments on the symposium in light of the biology of
U.S. reservoirs. In Man*-Made Lakes, R.H. Lowe-McConnell, ed., Academic
Press, N.Y., pp 205-208.
Symons, J.M. et al. 1964. Influence of impoundments on water quality.
Public Health Service Publ. No. 999-WP-18, 78 pp. 34, 46, 449.
et al. 1969. Water quality behavior in reservoirs. Public
Health Service Publ. No. 1930, Cincinnati, Ohio, 616 pp.
Tennessee Game and Fish Commission. 1972. Freshwater mussel ecology,
Kentucky Lake, Tenn. NTIS COM-73-10619.
Tennessee Valley Authority, Chattanooga, Office of Health and Environmental
Sci. 1972. Final environmental impact statement: Tellico Project.
Vol. 1, NTIS PB-200-025-F-1.
149
-------
U.S. Environmental Protection Agency. Data collected from the Coosa,
Chattahoochee, Escombia and Savannah Rivers by the Aquatic Biology Branch,
Region IV, Surveillance and Analysis Division, Athens, Georgia, unpublished.
U.S. Senate, Select Committee on National Water Resources. 1960. Fish and
wildlife and water resources. Committee Print No. 18, Washington, D.C.
Usinger, R.L., ed. 1971. Aquatic insects of California. Univ. of California
Press, Berkeley, Los Angeles, London.
Vanderhoof, R.A. 1965. Changes in waste assimilation capacity resulting
from streamflow regulation. In Symposium on Streamflow Regulation for
Water Quality Control, Public Health Service Publ. No. 999-WP-30, 420 pp.
Varley, J.D., A.F. Regenthal, and R. Wiley. 1971. Growth of rainbow trout
in Flaming Gorge Reservoir during the first six years of impoundment. In
Reservoir Fisheries and Limnology, Amer. Fish. Soc. Spec. Publ. 8, 511 pp.
Vollenweider, R.A. 1969. A manual on methods for measuring primary production
in aquatic environments. IBP Handbook No. 12, Blackwell, Oxford, 244 pp.
1970. Scientific fundamentals of the eutrophication of lakes and
flowing waters, with particular reference to nitrogen and phosphorus as
factors in eutrophication. OECD Tech. Rept. DAS/CSI/68.17, 159 pp.;
Annex Bibliography, 61 pp.
Waddy, B.B. 1966. Medical problems arising from the making of lakes in the
tropics. In Man-Made Lakes, R.H. Lowe-McConnell, ed., Academic Press,
N.Y., p 87.
Weber, G.I., ed. 1973. Biological field and laboratory methods for
measuring the quality of surface waters and effluents. Nat. Env. Res.
Center, Off. of Res. and Dev., EPA, Cincinnati, Ohio.
Welch, P.S. 1964. Limnological methods. McGraw-Hill, N.Y. 381 pp.
Wirth, T.L., R.C. Dunst, P.O. Uttormark, and W. Hilsenhoff. 1970.
Manipulation of reservoir waters for improved quality and fish population
response. Wisconsin Dept. of Natural Resources, Madison. NTIS PB-196-662.
Wistendahl, W.A. and K.P. Lewis. 1972. Willow Island Locks and Dam,
Ohio River, Ohio and West Virginia. Corps of Engineers, Huntington, W. Va.
150
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SECTION V
ECONOMIC, SOCIAL, AND AESTHETIC
IMPACTS RESULTING FROM RESERVOIR CONSTRUCTION
As is well known, site specific socioeconomic impact analysis
presents many challenges to the writers and reviewers of environmental
impact statements. The major problem in assessing socioeconomic impacts
is the cost of making reliable projections of site-specific changes.
Data inadequacies and the present state of the art of projection models
are the two problems which make reliable projections an expensive under-
taking. Because of the large number of unknown or difficult-to-predict
•
factors, estimates of future socioeconomic changes resulting from reservoir
construction and operations will necessarily be imprecise.
In spite of significant estimation problems, it is possible to
make general socioeconomic assessments based on the characteristics of a
reservoir project and a knowledge of existing conditions in the project
area. This section attempts to provide the impact statement reviewer
with a discussion of the general socioeconomic factors that should be
included in an impact statement. The section includes a proposed analytical
framework for structuring socioeconomic impact assessment as well as brief
descriptions of various categories of socioeconomic impacts. No attempt
is made to focus on regional considerations or to develop detailed empirical
documentation of impacts associated with specific reservoirs. Where lit-
erature on given impacts can be identified, references are included with
the description of the impact.
A GENERAL FRAMEWORK FOR ANALYZING
SOCIOECONOMIC IMPACTS
Socioeconomic impacts potentially can result from any type
of reservoir planning, construction or operation activity. Some impacts
may occur simultaneously with a particular activity. Others may require
several months or years before their full extent is known. Many times,
socioeconomic impacts may be the result of complex regional changes,
from which the reservoir effects are difficult to separate analytically.
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The general framework described below is an attempt to relate reservoir
activities to defined categories of socioeconomic impacts. As in any
general representation of a complex problem, arbitrary classifications
are unavoidable. The framework should be viewed with this limitation
in mind.
Project Activities
Socioeconomic impacts wj.ll result directly or indirectly from
specific activities under the following general headings:* •
• Project Planning
• Project Construction
• Project Operation and Output Characteristics.
The relationship and importance of these project areas to
socioeconomic impact assessment is discussed briefly below.
Project Planning -
Socioeconomic impacts can occur even before land for a
reservoir is acquired. These types of impacts relate directly to
the anticipation of future events caused directly or indirectly by
the reservoir project. For example, land values downstream from the
proposed project may be bid up in anticipation of flood protection benefits.
Other property value changes may occur if nearby residents anticipate
recreational development and increased traffic as a result of the reservoir.
Anticipation of future reservoir activities may also affect community
cohesion. Conflict between individuals supporting environmental preser-
vation and those promoting large scale economic development is a good
example.
* Section II of this report provides a detailed discussion of types of
project activities.
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Project Construction -
Socioeconomic impacts from construction of reservoirs are well
known. Among other things, they include displacement of individuals,
disruption of transportation routes resulting in change in community
cohesion, and change in recreational activities. Construction activities
which can lead to these changes include
• Development of access roads and power sources
• Clearing and excavation of the site
• Construction of dam
• Construction and development of associated
facilities.
Project Operation and Output Characteristics -
Socioeconomic impacts from operation of reservoirs will depend
primarily on the purpose of the project. General types of impacts include
change in property values, change in recreational activities, and change
in land use patterns. A primary consideration in assessing future changes
is the stimulus that the reservoir provides to regional economic development,
Operational factors that may cause Socioeconomic impacts include
9 Reservoir and downstream water level fluctuations
related to project function (hydroelectric,
irrigation, flood control, water supply and/or
recreation)
• Characteristics of newly created reservoir in
terms of location and size
• Characteristics and quantity of output of
reservoir (power, water supply, navigation,
flood control, etc.).
Jmpact Classification
Project activities will lead both directly and indirectly to
Socioeconomic impacts. Some types of impacts occur almost immediately
whereas others result over time through complex chains of interaction.
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For purposes of this report, project activities are seen as causing
certain fundamental environmental and economic alterations. These
alterations are not end products in themselves but are the basis for
broader socioeconomic effects. Alterations are defined as change in
physical/chemical, aesthetic, biological, and economic attributes resulting
directly from construction and operation of the project. The socioeconomic
effects that result from environmental and economic alterations are defined
as changes in various measures of human welfare. Traditional measures
relate to economic factors such as income, income distribution, property
values, and other asset prices. A less precise but equally as important
category of measures includes sociological and psychological phenomena
such as lifestyle and community cohesion.
Because there is no well defined cut off point for assessment
of socioeconomic impacts, a third category is included. This category
has various labels depending on one's particular background. It is often
called tertiary or ripple effects. These effects result when a reservoir
project promotes secondary economic development which in turn creates
environmental and economic alterations of its own. These additional
alterations may lead to socioeconomic affects similar to those caused
by the reservoir. For example, a water supply reservoir may increase
the capacity of a local water supply system. In combination with other
factors (access to product or other input markets, primarily), the
increased water supply may induce a water intensive industry, a brewery
for example, to locate in the region. Odor problems that are often
associated with breweries may in turn cause downwind residential property
values to decline relative to other comparable areas. This impact on
property values is termed a tertiary effect. Prediction of tertiary
effects can only be done in very general terms, due to the large number
of unknown factors that will influence such changes.
Figure 7 presents a list of alteration and effects categories
appropriate for assessing socioeconomic impacts. As shown in the figure,
project planning, construction, and operation/output characteristics are
depicted as causing certain fundamental physical/chemical, biological,
154
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Project
Planning
Project
Construction
Public and Private
Anticipation of
Alterations
Listed below
. 1-13
Environmental
and
Economic Alterations
Physical/Bio- (1)
chemical
Alterations
Habitat and (2)
Species Alter-
ations
Aesthetic
Alterations
(3)
Removal of (4)
land from
present use
(agricultural,
residential, etc)
Displacement (5)
of families
Relocation (6)
and/or blocking
of transportatior
utilities, etc.
Employment (7)
Requirements
Project (8)
material
requirements
Change in Com-(A)
munity Cohesion
(1-13)
SoCioeconotnic
Effects*
Change in(B;
unique natural
and/or man-made
resources
Change in (C)
recreational
activities
(1.2,3,4,9)
Change in (D)
property values
(1,2,3,4,6)
Change in (E)
income and income
distribution
(4,6,7,8,13)
Change in (F)
existing life
style
(4,5,6)
Migration (G)
(5,7,13)
Tertiary Effects
(A,B,C,D,E,F,G)
FIGURE 7. SCHEMATIC REPRESENTATION OF SOCIOECOMOMIC IMPACTS OF RESERVOIRS
* The alterations that generally cause each listed socioeconomic
effect are indicated by the numbers in parentheses.
155
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Project
Characteristics
Output and
Operation
Increased (9)
regional avail-
ability of flat
water areas
Physical/ (10)
chemical alter-
ations
Habitat and (11)
species alter-
ations
Increased (12)
and/or lower cost
water and power
supplies
Emp loyment
requirements
(13)
Development of (H;
recreation/service
related activities
and second home
(9)
Recreation use (I)
• boating
• fishing
• day use, etc.
(9,10.11)
Change in (J)
downstream recre-
ational activities
(10,11)
Agricultural (K)
development and/
or increased
intensity of
farming (12)
Tertiary Effects
(H.I.J.K.L.M.N)
Industrial
development
(12)
(L)
Residential (M)
development
(12)
Change in (N)
public expend-
itures and
revenues
(4,5,6,12)
FIGURE 7. (Continued)
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economic (and social) alterations. These alterations in turn will affect
various socioeconomic variables. The extent to which the socioeconomic
variables change will be related to many factors, including:
• Relative magnitude, duration, or frequency of
alterations caused by the reservoir (i.e., the
percentage change a reservoir causes in the
various alteration categories)
• Population density of the immediate region
» Industrial development history and potential
of the region (relating primarily .to access to
transporation systems, to raw materials, to labor
and other input markets, and to final product
markets)
• Proximity of the immediate region to major popu-
lation concentrations (relating primarily to
recreational use and second home development)
• Characteristics, extent and stability of the
ecologic and hydrologic systems altered by
the reservoir.
For each socioeconomic effect listed in Figure 7, the
alterations that may cause the effect are indicated by the numbers in
parentheses. The relation of socioeconomic effects to tertiary effects
is not treated explicitly due to the complexity of such relationships.
Instead, tertiary effects are treated as one category which is related
to the variety of socioeconomic effects. A brief description of each
of the alterations and effects identified in Figure 7 is presented
below.
SOCIOECONOMIC IMPACT DESCRIPTION
The following general format is used in describing alterations
and effects. For alterations, items discussed are definition, description,
and determining conditions. For the discussion of socioeconomic effects,
the same format is used except that the description relates alterations
to effects.
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As can be seen from Figure 7, similar types of alterations
may result from both construction and operation activities. The socio-
economic effects caused by these alterations are treated under one
heading (income, for example) with appropriate reference to the
distinction between the project related alterations causing the
particular effect. Also, socioeconomic impacts caused by project
planning are shown as the result of anticipation of the specified
construction and operation alterations.
Environmental and Economic Alterations
Planning and Construction Phases
Public and Private Anticipation of Alterations. Most of the
political and interest group conflicts associated with a particular
reservoir occur in anticipation of reservoir related alterations and
effects. The community effect caused by these anticipations will be
related to several factors including:
• Number of individuals affected by various
anticipated alterations
• Magnitude, character, and duration of anticipated
alterations
• Relative political influence of affected individuals
(relating primarily to their position in the com-
munity, their source of employment, their income
levels, their education and background, and their
tastes and preferences)
• Proximity of alterations to individuals' property
• Regional and national importance of resources that
will be altered by construction and operation of
the reservoir.
Literature on the relation of anticipated alterations to
socioeconomic effects will be presented below in the discussion of
various effects. Explicit consideration of anticipation is treated
by Smith (1970).
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Physical/Biochemical Alterations (Box No. 1) -
These factors are discussed in detail in Section III. They
include fundamental changes in biochemical characteristics of a river
system due both to reservoir construction and to changes in the basic
flow regimes affecting ground and surface water. Physical/biochemical
alterations are included in Figure 7 to show the conceptual relation
of environmental alterations to socioeconomic effects.
Habitat and Species Alterations (Box No. 2) -
These factors are discussed in detail in Section IV of the
report and are included in this section for the same reason as physical/
biochemical alterations. Habitat and species alterations involve direct
removal of various classes of habitat (aquatic, marsh, and terrestrial)
and the associated destruction of organisms that are unable to migrate
from the affected area.
Aesthetic Alterations (Box No. 3) -
These alterations include changes in the natural or man-made
visual appearance and alteration in amenity characteristics due to
reservoir construction and operation. They include changes in:
• Land (such as surface configurations, land
appearance, alignment of streams and reservoir
shoreline, and geological surface material)
• Water (in terms of flow, clarity, water level,
floating material)
• Biota (such as vegetation, animal life, aquatic
life)
• Man-made Structures (such as the dam itself,
power transmission lines, and other support
facilities)
• Noise
• Odors.
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The magnitude of aesthetic alterations will be determined by such
factors as the relative uniqueness of aesthetic characteristics that are
altered or created, distance that the structures are visible, their
height, the materials used in the construction, the extent and magnitude
of changes in vegetation along shore lines and the extent of other physical/
chemical alterations that may cause odor and plant growth (e.g., algae)
problems.
Removal of Land from Present Use (Box No. 4) -
This alteration involves the change in land use status resulting
from pre-emption of present uses for the reservoir site and other related
facilities. Land use changes resulting from reservoir sites could con-
ceivably be at the expense of a variety of present uses including:
• Agricultural
• Woodland
• Waste land
• Parks or recreational areas.
This alteration is related directly to the extent and size of
the given reservoir project (i.e., the number of surface acres inundated
as well as land taken adjacent to the reservoir for associated purposes
(Higgins, 1967).
Displacement of Families (Box No. 5) -
Most major reservoirs will involve the displacement of some
individuals residing in the areas to be flooded. The extent of this
alteration will depend on the population density of the project site
as well as the extent of the project. Socio-psychological effects
will be discussed in the "effects" part of this section. Some of
the factors involved are discussed in various reports and articles
(Napier, 1972; Ludtke, et al., 1970; Burdge and Ludtke, 1970).
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Relocation of Transportation Systems, Utilities,
Cemeteries, and Other Public and Private
Facilities (Box No. 6) -
Utilization of certain areas for a reservoir site will require
either abandonment of existing roads, and/or rerouting of these roads
around the high water areas. Similar rerouting may be necessary for
power lines, railroads, and possibly for water and sewage facilities.
Movement of cemeteries is also often a major problem. The magnitude
of this alteration will be directly related to the extent of urbanization
in the area.
Employment Requirements (Box No. 7 and 13) -
Reservoir operation and construction activities create demands
for various categories of labor and skilled personnel. Relative mag-
nitude of the demand for labor will depend on the scale of the project
and the type of facilities (hydroelectric, flood control, etc.) that
are being built. General figures on labor requirements are described
in various publications ("Labor and Material Requirements...", 1964;
Hannon and Bezdek, 1973; Krutilla and Haveman, 1968).
Project Material Requirements (Box No. 8) -
Construction and operation of reservoir projects will also
set up demands for specific building materials, aggregates, construction
supplies, and other items potentially drawn from the region. The mag-
nitude of this alteration will again be a direct function of the relative
scale of the project and the availability of local supplies. The
reference provided for the previous category provides general guidance
on material requirements.
Environmental and Economic Alterations
Operation Phase
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Increased Regional Availability of Flat Water Areas (Box No. 9) -
Construction of a reservoir will increase total acreage of
surface waters available in the project region. The size of increase
will be directly related to the project purpose, specific modifications
in project design aimed at increasing or maintaining minimum pool
elevations to maximize surface acreage, and the overall scale of the
project. The extent to which increased flat water area will benefit
related recreation activities (motor boating, swimming, lake fishing,
sailing, etc.) will depend on the number of other lakes and reservoirs
in the region and on the regional population density and socioeconomic
characteristics. Recreation aspects will be discussed in the "effects"
portion of this section.
Physical/Chemical Alterations (Box No. 10) -
Reservoir operations will create a variety of physical/chemical
alterations, described in detail in Section III of this report. These
alterations are identified in this section of the report in order to
show their general relationship to socioeconomic effects.
Habitat and Species Alterations (Box No. 11) -
Reservoir operations (downstream water level fluctuations, for
example) may cause alteration in the habitat of certain aquatic species.
These types of impacts are discussed in detail in Section IV of the
report. They are included in the socioeconomic section in order to
indicate the general relationships.
Increased and/or Lower Cost Water and Power Supplies (Box No. 12) -
Depending on project purpose and design, regional availability
of water supply and power may be increased as a result of a reservoir
project. These output characteristics will in turn create certain
locational and development incentives which are discussed in the "effects"
portion of this section.
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Socioeconomic Effects
A general list of socioeconomic effects that may result from
the preceding list of reservoir-related alterations is described below.
The reader should refer to Figure 7 for a summary description of the
relation of alterations to effects.
Change in Community Cohesion (Box A) -
Reservoir projects will impact various community and regional
interest groups differently. Those groups of individuals who may lose
real and perceived values because of the project are likely to come
into conflict with those that stand to gain from the project. Many of
these conflicts and the effects on community cohesion will occur at
the planning and design phase of reservoir projects. Since most viable
communities undergo change and growth, the significance of interest
group conflicts due to a reservoir project will probably diminish with
time. More significant will be the changes in lifestyle (Box E),
due to displacement of individuals and alterations in land use patterns.
General literature on effects of reservoir and water resource projects
is presented in Napier (1971); Napier (1972); and Andrews, et al (1972).
Change in Unique Natural and Man-Made Resources (Box B) -
This effect involves degradation, impairment, or loss of
unique natural environments and/or man-made resources of unique value.
Unique natural environments would be defined as ecologically or geo-
logically rare areas of which the total regional or national supply
is strictly limited. Man-made resources could include historical
areas, areas of architectural significance, areas of educational
interest, or areas with archeological values. Several factors may cause
deterioration or loss of unique natural or man-made areas. These factors
include physical/chemical alterations (Box No. I), habitat and species
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alterations (Box No. 2), aesthetic alterations (Box No. 3), and removal
of land from present uses (Box No. 4). Change in unique and natural
man-made areas will, of course, be dependent on their presence in the
project site and immediate area.
Loss of unique or natural man-made resources will have many
ramifications. It decreases their abundance on a national basis and
creates a regional loss if they are an attraction of importance for
visitors from other regions. Loss of visitation will create an
economic decline^ associated with this activity and result in displace-
ment of certain activities in the regional economy. Loss of unique
natural man-made resources will also create psychological losses for
certain members of communities, depending on their preferences and
perceptions. Irreversible change in the status of these resources
represent a loss not only to regional inhabitants but to the nation
and to future generations.
Change in Recreation Activities (Box C) -
This effect involves changes in present activity patterns
associated with the reservoir site. (Recreational use of the reservoir
and downstream recreational use will be discussed separately below.)
Items of major interest include the type and extent of hunting, the
type and extent of river fishing, the utilization of the river for
canoeing and related free-flowing water activities, and the utilization
of the area for other recreational pursuits such as hiking, camping,
picnicking, and nature study and observation. Factors causing change
in these activities are the same as those for the above effect:
• Physical/biochemical alterations (Box 1)
• Habitat and species alterations (Box 2)
• Aesthetic alterations (Box 3)
• Removal of land from present use (Box 4).
Factors determining the extent of change relate primarily to the scale
of the reservoir project and the present (or potential) activities in
the site area. Tertiary effects include decline in employment of stream
related recreation enterprises.
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Change in Property Values (Box D) -
Change in property values involves an increase or decrease
in the average values of specific properties over and beyond that which
would normally occur without the reservoir. Construction and operation
activities can cause change in property values of a temporary or permanent
nature for several reasons. These include:
• Aesthetic deterioration due to alterations of
the environment around the construction site
(Box No. 3)
• Removal of certain parcels of land from present
use
• Alteration in the physical or biochemical environ-
ment creating odor or other aminity problems
• Creation of development potential due to reservoir
operation and output characteristics
• Creation of traffic and congestion associated with
recreational use.
Conditions determining the effect on property values are related to
two important factors. One is the sensitivity of the present use to
alterations in the surrounding environment. Impact on agricultural
use will probably be minimal from aesthetic or amenity alterations in
the neighborhood of the reservoir. On the other hand, proximity to
residential areas (during the construction phase) may have a retarding
effect on property values. This effect will primarily be evidenced
as a slower rate of increase rather than any noticeable decrease.
Proximity to urban areas and potential recreation demand will also play
an important role in property value changes.
Tertiary effects from change in property values are hard to
trace and all that can be done is to identify potential areas of concern.
One of these relates to Box D in terms of change in income. Effects on
property values also may have broader effects in terms of changing the
character of neighborhoods or altering the development characteristics
of a particular area. Literature includes Milliken (1967) and Drucker
(1972).
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Change in Income and Income Distribution (Box E) -
Change in income involves an increase or decrease in the
annual wages, salaries, interest, profit, or rent received by individuals
in the region of the reservoir. Several alterations can cause a change
in income. These include:
• Removal of land from present use (Box No. 4)
• Disruption of transporation (Box No. 6)
• Project employment requirements (Box No. 7)
• Project material requirements (Box No. 8)
• Developmental stimulus provided by the
reservoir outputs.
Construction of the reservoir will alter income by taking certain lands
out of production, by creating demands for certain factors of production
such as labor or raw materials, and by causing temporary changes in the
income earning capacity of the land due to disruption of transportation
or other public service systems. The conditions determining the magnitude
of these effects will be related to the present use and economic activity
in the neighborhood of the reservoir as well as the scale of the project.
Development of land surrounding the reservoir and industrial location
may also result in new sources of income for the region.
Factors determining the magnitude of changes in income
distribution include:
• Employment and skill categories required in
construction and operation of the reservoir
• Patterns of land ownership
• Magnitude of development stimulated by presence
of the reservoir and ownership of income earning
assets which are positively or negatively affected
by development
• Methods of financing public services needed as a
result of development.
For example, if large numbers of unskilled workers are employed
at high wages, one could expect an increase in income in those categories.
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If marginal farmers are forced off the land because of the project,
decreases in income to these individuals could be expected.
Tertiary effects will depend on the magnitude of the project
relative to present activities. In most cases, change in income
earning capacity of labor and assets in the region will have a multiplier
effect through expenditure of income on consumer goods and services.
These expenditures may in turn create demands for further consumer
serving businesses which will generate additional sources of regional
income. Other income generation factors relate to industrial location
and secondary development, as discussed below. More detailed material
on the subject is given in U.S. Department of Labor, Bureau of Labor
Statistics (1964), Saitta and Bury (1973), Levin (1969), and Andrews (1972).
Change in Existing Life Styles (Box F) -
This effect involves the disruption of existing social patterns,
means of livelihood, or particular characteristics associated with work,
recreation, and social tradition in a given region. The major alterations
which will effect life style include the removal of land from present use
(Box No. 4), displacement of families (Box No. 5), and relocation or
blocking of transportation and utilities (Box No. 6). Each of these
alterations has a potential for causing major shifts and change in
existing work and activity patterns. Alteration of the physical and
ecological environment also can produce changes in existing life styles.
This results because of alterations in the character of the area and
because of change in recreational activities that may follow (Box C
above). Industrial, recreational, residential, and agricultural develop-
ment (discussed below) may also cause change in existing life styles.
Alteration of life style will be a direct function of the scale of the
project as well as the uniqueness of the life style in a given area.
Areas with considerable urbanization can be expected to suffer lesser
magnitude effects than areas with rural character or deeply ingrained
traditions.
Tertiary effects from change of life style are often difficult
to separate from pervasive technical, economic, and social trends in
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society as a whole. Tertiary effects that can be identified include
other socioeconomic effects such as change in recreational activities
(Box C), and out migration (Box G). Other tertiary effects might be
found in urban areas to which displaced or unemployed people migrate.
These effects could include increased welfare payments, unemployment,
or other related urban social problems.
Literature on the subject includes those references cited
under "displacement of families" as well as Baur (1973), Utah State
University (1968), Andrews (1972), and Prebble (1969).
Migration (Box G) -
This effect involves the voluntary or involuntary movement
of people over a specified distance. Alterations causing migration
include removal of land from present use (Box No. 4), displacement of
families (Box No. 3), and employment requirements (Box No. 7). Con-
ditions determining the magnitude of this effect will be related to
the population density of the reservoir area, job opportunities in
the immediate area as present economic activities are displaced, and
the distance to other major areas of employment. Mobility of families
based on educational level and training will also be a factor in the
degree of migration that occurs.
Tertiary effects relate to other socioeconomic effects such
as change in existing life style (Box F) and to increased social
problems in urban areas.
References on migration and displacement were presented
previously in the discussion of "displacement of families" (Box No. 5),
Development of Recreation/Service Related
Activities and Second Homes (Box H) -
Development of a reservoir creates new water areas on which
flat water recreation can be pursued. This in turn may stimulate private
investment in service and supply related activities. It is also possible
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that land adjacent to the reservoir may be developed over time for second
homes. Primary characteristics determining the potential for these
developments will be the physical dimensions of the reservoir, its
surface area, and its general attractiveness. Conditions which will
determine the extent of these developments include the proximity to
urban areas and to interstate highway systems, income levels in the
region, and the availability of alternative areas of similar character-
istics.
Tertiary effects and pertinent references are discussed below
under recreational use. One specific study on second home development
has been conducted by Burby (1971).
Recreational Use (Box I) -
Creation of a reservoir and the provision of associated
facilities and services will result in certain recreational use.
Recreational use may include boating of various types (power boating,
sailing, canoeing), fishing, day use (such as hiking and nature obser-
vation), and overnight camping. The extent of recreational use will
be determined by the features of the reservoir, population density,
per capita income levels in the region, and the availability of other
recreational areas. Limitation on use may result if physical/chemical
changes create offensive water quality conditions or undesirable
ecological changes.
Tertiary effects of recreation development will relate to
two important areas. One is the environmental impact these developments
and their use cause. The other is the economic implications in terms
of income and employment. Development of recreational facilities and
private enterprises requires construction and facilities development
which generates its own forms of land use change and potential environ-
mental degradation. For example, traffic congestion and boating use
on the reservoir have potential environmental impacts. The extent of
these impacts and their importance will be determined both by the
magnitude of recreation use and facility development (including second
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home development). Also the size of the reservoir project and its
ability to assimilate both pollutants and large numbers of recreationists
will determine the significance of this tertiary effect.
The other aspect of recreation development is the generation
of income and employment. Construction and operation facilities will
mean employment and income to residents of the region. This may have
positive effects on unemployment, welfare payments, and in the long run,
on overall education and health levels of the population.
Development of the area for recreational activities will also
have a tertiary effect in terms of relation to life style (Box F).
Certain lands may go out of one type of land use (agriculture, for
example) and be put to more intensive uses such as marinas or boat
sales and service facilities. References on the general subject of
recreation development and use include Saitta (1973), U.S. Department
of Interior (1971), and Milliken and Mew (1969).
Change in Downstream Recreational Activities (Box J) -
Reservoir operation may lead directly or indirectly to change
in recreational activity patterns below the reservoir. These may include
increased fishing in the tail race and change in the type of fishing and
hunting activities conducted in reaches below the reservoir. Alterations
which will be significant in causing such changes include habitat and
species alterations due to altered habitat (water level fluctuations)
and physical/biochemical alterations causing subtle changes in riverine
ecology. These alterations and impacts are discussed in Sections III
and IV. Conditions determining the magnitude of change in downstream
recreational activities will depend on present activities, sensitivity
of the environment to subtle biochemical/physical alterations, and
the scale of the project relative to the overall minimum, average, and
maximum stream flows.
Tertiary effects relate to change in life style (Box F) and
indirectly to certain changes in income earning capacity of enterprises
which cater to existing recreational activities. References on the subject
include Dearinger (1968), Dearinger and Woolrine (1973), and Bianchi (1969).
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Agricultural Development and/or Increased
Intensity of Farming (Box K) -
Depending on project purpose, a reservoir project may lead
to agricultural development or more intensive farming on already irrigated
lands. Alterations that will create this potential relate primarily to
the increased availability of water or lower cost water supplies. Con-
ditions which will permit realization of these potentials include the
fertility of the soil, development costs in the area, access of the area
to markets, and overall level of demand for agricultural products.
Tertiary effects from agricultural development include both
the regional economic stimulus (wages and income) and environmental
changes in terms of potential degradation of waterways (from erosion,
pesticide, and fertilizer run off) and alteration of local terrestrial
ecology due to clearing of vegetation. In the extreme, secondary
developments in housing and support facilities for agricultural develop-
ment could be expected. The conditions determining these tertiary
effects will be directly related to the purpose of the reservoir
project and the market potential for development. References on the
secondary stimulus of agricultural development may be found in various
Department of Agricultural experiment station reports and in agricultural
economic journals. Bureau of Reclamation publications are another possible
source of information. Other references include Rainer and White (1971),
Regan and Timmons (1954), Regan and Steel (1957), Hargrove (1971), and
Leven (1969).
Industrial Development (Box L) -
Power and water outputs from the reservoir may induce certain
industrial locations in offsite areas. Alterations creating this
potential will relate directly to increased and/or lower cost water and
power supplies (Box No. 12). Conditions determining realization of the
potential will relate to the proximity of the reservoir to urban areas,
the requirements of industries for water and power supplies, and the
proximity of the region to broader regional and national markets.
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Tertiary effects again relate to environmental and economic
factors. Industrial development has the potential for altering land
use through its own location. Corresponding population increases may
result from influx of workers with demands for homes, retail services,
and public facilities and services. All of these potential develop-
ments in turn have environmental consequences and effects associated
with them. These involve impacts on several of the alterations areas
such as physical/chemical and habitats and species. Alterations also
occur through pollution and physical removal of habitat.
References on industrial development stimulus provided by
reservoirs include Regan and Steel (1957), Hargrove (1971), and Leven
(1969).
Residential Development (Box M) -
Residential development will be intimately related to many
of the other socioeconomic effects such as recreational use, industrial
or agricultural development, and to alterations involving increased or
lower costs water supplies. Conditions determining residential develop-
ment will relate directly to the economic development potential facili-
tated by construction and operation of the reservoir.
Tertiary effects will be similar to those discussed above
under industrial development and relate to change in land use and
environmental side effects through the increased urban runoff, air
pollution, and ecological changes.
References include many of those already presented,
especially Burby (1971).
Change in Public Expenditures and Revenues (Box N) -
Recreational use, residential and industrial development, and
regional population growth may result directly or indirectly from reservoir
projects. These developments in turn create demands for public services
(roads, schools, water and sewer, police and fire protection, etc.) and
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create new sources of revenue (state and local income taxes, state
excise taxes, municipal and county property taxes, and user charges).
Determining the net effects on public expenditures is an important
consideration in analyzing socioeconomic effects including income
distribution, community cohesion and regional economic stimulus.
References include Saitta (1973), Bates (1970), Drucker (1972), and
Smith (1972).
SUMMARY
This section presented a very general framework for identifying
the socioeconomic impacts of reservoir projects. In using the framework,
the impact statement reviewer should refer to the various footnotes cited
for each impact area. These references provide in depth treatment of
technical and conceptual aspects of socioeconomic impact evaluation as
well as examples of specific case studies. An excellent general
reference is "Water Policies for the Future" (National Water Commission,
1973). The reviewer should also keep in mind the limitations of arbitrary
classification schemes, including the one presented in this section.
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REFERENCES
Andrews, W.H., et al. 1972. Identification and measurement of quality of
life elements in planning for water resources development: an exploratory
study. Research Rept. No. 2. Institute for Social Science Research
on Natural Resources, Utah State University, Logan, Utah.
Bates, C.T. 1970. The effect of a large reservoir on local government
revenue and expenditure. Univ. of Ky. Water Resources Institute
Research Rept. No. 23, Lexington.
Baur, E. 1973. Assessing the social effects of public works projects.
Resident Scholar Program Research Paper No. 3, Dept. of the Army,
Corps of Engineers, Fort Belvoir, Va.
Bianchi, D.H. 1969. Economic value of streams for fishing. Univ. of
Ky. Water Resources Institute Research Rept. No. 25, Lexington.
Burby, R.J. III. 1971. A model for simulating residential development
in reservoir recreation areas. Water Resources Research Institute
Rept. No. 52, Center for Urban and Regional Studies, Univ. of N.C.
Chapel, Hill.
Burdge, R.J. and R.L. Ludtke. 1970. Factors affecting relocation in
response to reservoir development. Univ. of Ky., Water Resources
Institute Research Rept. No. 29, Lexington.
Dearinger, J.A. and G.M. Woolrine. 1971. Measuring the intangible
values of natural streams, part 1, application of the uniqueness
concept. Univ. of Ky. Water Resources Institute Research Rept.
No. 40., Lexington. (Part 2, 1973).
. 1968. Esthetic and recreational potential of small
naturalistic streams near urban areas. Univ. of Ky. Water Resources
Institute Research Rept. No. 13, Lexington.
Drucker, P. 1972. Impact of a proposed reservoir on local land values,
anthropological analysis of social and cultural benefits and costs from
stream control measures, phase 3. Univ. of Ky. Water Resources Institute,
Lexington.
Hannon, B.M. and R.H. Bezdek. 1973. Job impact of alternatives to
Corps of Engineers projects. Engineering Issues, ASCE.
Hargrove, M.B. 1971. Economic development of areas contiguous to
multipurpose reservoirs: the Ky.-Te. experience. Univ. of Ky.
Water Resources Institute Research Rept. No. 21, Lexington.
174
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Higgins, J.M., Jr. 1967. The effect of landowner attitude on the
financial and the economic costs of acquiring land for a large
public works project. Univ. of Ky. Water Resources Institute
Research Rept. No. 3, Lexington.
John Hopkins Press. 1968. Idle capacity and the evaluation of public
expenditures. Published for Resources for Future, Inc. Table 6:
20-21.
Levin, C.L. ed. 1969. Development benefits of water resources
investments. Report to U.S. Army Engineer Institute for Water
Resources by Washington Univ., St. Louis, Mo., IWA Rept. 69-1.
Ludtke, R.L., et al. 1970. Evaluation of the social impact of reservoir
construction on the residential plans of displaced persons in Ky. and
Ohio. Univ. of Ky. Water Resources Institute Research Rept. No. 26,
Lexington.
Milliken, J.G. and H.E. Mew, Jr. 1969. Economic and social impact of
recreation at reclamation reservoirs. Prepared for U.S. Dept. of
Interior, Bureau of Reclamation by Denver Research Institute, Univ.
of Denver.
Napier, T.L. 1972. Social-psychological response to forced relocation
due to watershed development. Water Resources Bulletin 8(4):784-794.
. 1971. The impact of water resource development upon local
communities: adjustment factors to rapid change. Unpublished Ph.D.
Dissertation, The Ohio State Univ.
National Water Commission. 1973. Water policies for the future.
Final Rept. to the President and to the Congress of the U.S.
Washington, D.C.
Prebble, B.R. 1969. Patterns of land use change around a large
reservoir. Univ. of Ky. Water Resources Institute Research Rept.
No. 22, Lexington.
Proceedings of the workshop for sociological aspects of water resources
research. 19 . Held at Utah State Univ., Logan, Utah, April 18-19.
Rainer, R.K., and C.R. White. 1971. Identification and interrelationships
of secondary benefits in waterways development. Water Resources Research
Institute Bulletin 711. Auburn Univ., Auburn, Alabama.
Regan, M.M. and H.A. Steel. 1957. Recent developments in watershed
programs in committee on the economics of water resources development
of the western agricultural economics research council. Water
Resources and Economic Development of the West, Rept. No. 6: Small
Watershed Development; Rehabilitation and Reorganization of Irrigation
Projects, Berkeley, Gal., Nov. 13-15, pp 1-11. (With comments by
Andrew Vanvig, same publication, pp 13-15.)
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Regan, M.N. and J.F. Timmons. 1954. Current concepts and practices in
benefit-cost analysis of natural resource developments. In Committee
on the Economics of Water Resources Development of the Western
Agricultural Economics Research Council. Water Resources and Economic
Development of the West, Rept. No. 3: Berkeley, Cal., Dec. 27. pp 1-5.
Saitta, W.W. and R.L. Bury. 1973. Local economic stimulation from
reservoir development: a case study of selected impacts. J. of
Soil and Water Conservation. March-April, pp 80-85.
Smith, C.R. 1972. Social and cultural impact of a proposed reservoir
on a rural Kentucky school district. Univ. of Ky. Water Resources
Institute Research Rept. No. 59, Lexington.
. 1970. Anticipation of change: a socioeconomic description
of a Kentucky county before reservoir construction. Univ. of Ky.
Water Resources Institute Research Rept. No. 28, Lexington.
U.S. Army Corps of Engineers. 1964. Labor and material requirements
for civil works construction. Bureau of Labor Statistics Bulletin
1309.
U.S. Department of Interior, Office of Water Resources Research. 1971.
Socioeconomic study of multiple use water supply reservoirs. Report
by Ralph Stone and Company, Inc. Los Angeles, Cal.
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SECTION VI
REVIEW CRITERIA
Environmental impact statements on reservoir construction
activities provide information about how a proposed project will affect
the environment. If well done, an impact statement can be an important
summary of information vital to the decision-making process. In addition,
the impact statement will generally be the principle source of information
about a project and its implications available to the public at large.
Consequently it is essential that the statement cover all significant
factors and provide accurate, useable findings. The difficult function
of an EPA reviewer is to determine whether the information contained in
the statement is complete and accurate.
One approach, of course, is for the reviewer or decision-maker
to duplicate the analysis and develop his or her own environmental state-
ment. This may be the surest way, but it is certainly not efficient in
terms of time and resources required to do the job. It essentially
requires a doubling of resource requirements for every statement developed.
A second approach is to utilize a set of predetermined criteria
against which the completeness and accuracy of a statement can be tested.
This approach, while less certain of identifying inadequacies, can provide
a reasonably sound evaluation of a statement in a short period of time
with a minimum of resources.
The purpose of this section is to provide such criteria for
judging impact statement adequacy and completeness. It should be
emphasized that the function of these criteria is to assure that the
most important questions are asked during the course of a review; not
to provide an assessment of overall project acceptability.
Two levels of review criteria are important. One level uses
information such as that provided in the Water Quality Impacts and
Ecological Impacts sections of this report to ask rather detailed questions
about specific aspects of the environment that may be impacted by reservoir
construction. This research has not attempted to develop a complete list
of such specific criteria for any impact area but does suggest several
important considerations, particularly on pages 97 through 129.
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It is difficult, however, to assess the completeness and accuracy
of an environmental impact statement with respect to specific impact areas
without some feel for the degree of confidence that can be placed in more
general information regarding the project and its impacts. For this reason,
a set of general review criteria are needed, applying to the impact state-
ment as a whole. Such a set is presented in Table 13 and discussed in
the following pages.
No strictly objective procedures can be developed that will
adequately evaluate all possible impact statements. The use of both
general and specific review criteria must be tempered by the judgment
of the reviewer--especially in determining when an item may or may not
be significant and when the level of accuracy is adequate or inadequate.
Unique site characteristics, extenuating circumstances, and gradation of
impact will require that the reviewer be the ultimate judge of the adequacy
of impact statements.
GENERAL REVIEW CRITERIA
Completeness
Project Description -
The project description should include detailed project maps
showing the layout of buildings, dams, and other structural changes,
engineering designs and drawings depicting construction details, operating
procedures, and equipment to be employed. The visual aspects of the
entire project should be presented in architectural drawings.
In addition, the project description should include plans for
inspection and monitoring programs and contingency plans for environmental
quality'control throughout the reservoir construction and operation phases.
The flow of materials to and from the project site should also be discussed,
including the quantities and sources of raw materials and the sources and
shipping routes of these materials if pertinent.
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TABLE 13
GENERAL ENVIRONMENTAL IMPACT STATEMENT REVIEW CRITERIA
Completeness
1. Project Description. Are the proposed project activities
adequately described, through the inclusion of sufficient maps,
sketches, construction timetables, etc.?
2. Present Situation. Are present conditions in the project area
adequately described in terms of land use, environmental, economic,
and social conditions?
3. Project-Caused Impacts. Has an explicit attempt been made to
isolate project-generated impacts from other changes in the
project area resulting from activities not associated with the
proposed project?
4. Timing and Duration. Does the statement indicate precisely when
specific project activities will take place and for how long a
time they will be continued?
5. NEPA Points. Does the statement include all the required con-
tents specified in NEPA and in subsequent CEQ guidelines?
6. Data Sources. Are the sources of all information used to pre-
dict and evaluate environmental impacts adequately documented?
7. Tool Identification. Are the specific analytical tools, models,
or methodologies employed to predict impacts or evaluate impact
significance identified?
8. Analyst Identification. Are those individuals who conducted the
actual impact analysis identified by name and background?
9. Uncertainty and Risk. Does the statement indicate the analysts'
level of confidence in the predicted impact magnitudes? Does the
statement discuss (or explicitly assert the nonexistence of) any
high risk-low probability impacts?
10. Affected Parties. Does the statement specifically identify those
segments of the public who will be directly impacted by the project?
11. Key Issues. Does the statement include a summary, highlighting the
most important conclusions of the analysis that may be important in
the making of a public decision?
Accuracy
1. Geographic Scope. Are the geographical boundaries used for analysis
broad enough to include all identifiable impacts or can the reviewer
identify potentially important impacts in areas outside those
boundaries?
2« Time Scope. Has the entire time frame of the project been analyzed
for potential impacts, including construction, operation, and
ultimate disposal of the site?
3. Methods and Procedures Accuracy. Does the reviewer have any basis
for asserting that the analytical procedures used in identifying
and measuring impacts are inadequate or inappropriate?
4. Data Reliability. Does the reviewer have any basis for questioning
the accuracy, reliability, or appropriateness of data cited to
support conclusions?
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TABLE 13. (Continued)
Analyst Qualifications. Assuming the responsible impact analysts
are identified, are their areas of expertise and backgrounds
appropriate to impacts in question?
Magnitude vs. Importance. Does the impact statement make a clear
distinction between the predicted size of impacts (magnitude) and
the significance of these impacts (importance)?
Evaluation Documentation. Does the statement identify the rationale,
criteria, or other bases supporting any subjective judgments of
impact significance?
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Present Situation -
The description of the existing situation should include maps
and tabulations of current land use in the entire region that may be
affected by the project. Also, current types, levels, and trends in
economic and social activities in the region should be detailed and
quantified (e.g., population, housing, number of employees, and output
of major firms; number of annual user days at each recreation site,
etc.).
The ecological characteristics of the area should also be
detailed and their relationships to areas and activities outside the
direct influence of the project should be clearly described. Current
environmental conditions should be quantified, and also described in
terms of trends. Air and water quality, noise levels, traffic patterns,
levels of existing resources and services (water supply, sewage treat-
ment and disposal, power) must all be identified and described. All
the foregoing data should be consistent with current official data
available to the reviewer.
Project-Caused Impacts -
Since changes in the economic, social, and environmental
characteristics of the region will undoubtedly occur with or without
the project, it is important that those impacts specifically attributable
to project activities be identified as separate from changes expected to
be produced by other causes.
Timing and Duration -
The temporal pattern of environmental impacts is an important
issue often overlooked. Reservoir construction projects may have markedly
different impacts, particularly in the areas of water quality and ecology,
during the construction phase, during early operational phases, and as the
project nears the end of its useful life. The potential for such signif-
icantly different impacts over time should be addressed in the impact
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statement as should the duration of such impacts; that is, does an
impact occur once for a brief period, once for an extended or permanent
period, or repeatedly in a cyclic manner?
NEPA Points -
A complete environmental impact statement must, as a minimum,
address the specific points of statement content set forth in the
National Environmental Policy Act of 1969 and in subsequent guidelines
put forth by the Council on Environmental Quality (CEQ). The most
recent CEQ guidelines, dated August 1, 1973, identify eight specific
content areas required:
• Description of the proposed action
• Relationship of the proposed action to land use plans,
policies, and controls for the affected area
• Probable impact of the proposed actions on the
environment
• Alternatives to the proposed action
• Any probable adverse environmental impacts which
cannot be avoided
• Relationship between local short-term uses of man's
environment and the maintenance and enhancement of
long-term productivity
• Any irreversible and irretrievable commitments of
resources
• An indication of what other interests and considerations
of Federal policy are thought to offset the adverse
environmental effects identified.
Data Sources -
Data used in predicting and evaluating impacts should be
adequately documented so that decision makers, members of the public,
or the reviewer can consult original sources for further information or
verification. Such specific citation is a required first step in the
analysis of data accuracy and reliability.
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Tool Identification -
As is illustrated in the Water Quality Impacts and Ecological
Impacts sections of this report, a variety of techniques may exist for
predicting impacts in any given area. Since each technique is appropriate
in some circumstances but not in others identification of the specific
techniques used is a prerequisite to the reviewers' analysis of tool
appropriateness.
Analyst Identification -
NEPA requires that impact analyses be conducted by an inter-
disciplinary team. An environmental impact statement should identify
this team both by name and by area of expertise.
Uncertainty and Risk -
In all project situations, some impacts are virtually certain
to occur while others are very difficult to predict with confidence,
being highly dependent on future events. A complete environmental
impact statement should indicate the level of confidence the analysts
have in impact prediction. This information is particularly important
when impacts are quantified. An adequate impact statement should also
identify any impacts of low probability but high damage or loss potential.
If no such high risk impacts can be foreseen the statement should so state.
Affected Parties -
Since an impact statement is intended to communicate infor-
mation to the public, wherever identified impacts will impinge upon a
specific segment of that public, defined in either geographic or socio-
economic terms, the group should be specifically identified. For example,
reservoir construction frequently replaces a cold, flowing water fishery
with a warm, still water one. Typically, a distinctly different group
of recreationists will utilize these two fisheries.
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Key Issues -
An impact statement must be comprehensive and discuss all
identifiable impacts, but it must also provide some guidance for public
decision making. The key conclusions of the impact analysis, including
expected major positive impacts, major negative impacts, areas of little
or no impact, and levels of certainty should be given special prominence
to guide public discussion.
ACCURACY
Geographic Scope -
Important environmental impacts may frequently occur outside
the immediate project area and should be identified in the impact
statement. Such impacts are particularly important in reservoir projects
where major downstream alterations can be expected. Any geographical
boundaries chosen for analysis are artificial and in some sense arbitrary,
but the boundaries utilized in any impact statement analysis should be
clearly specified and the reviewer should be unable to cite any specific
project-related impacts identifiable outside the region of analysis.
Time Scope -
Impacts should be analyzed over the entire life span of a
project, including construction, operation, and final disposition of
the reservoir site. An adequate impact statement should address all of
these periods and assign specific dates to them as well. A statement
is inadequate if the reviewer can identify an impact directly generated
by the project occurring outside the time scope of analysis.
Methods and Procedures Adequacy -
The reviewer must evaluate the adequacy of analytical techniques
used in the impacts analysis. Impact statement accuracy can be judged
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satisfactory only if the reviewer concludes that the techniques used
to identify, predict, and evaluate impacts are appropriate to the cir-
cumstances and warrant the conclusions made. Data such as that provided
on water quality and ecological impact prediction methodologies presented
in other sections of this research will be required by the reviewer in
making this evaluation.
Data Reliability -
Regardless of the techniques employed, impact assessments may
be invalid if the data used is incomplete, unreliable, out of date, or
statistically inadequate. Though it may be difficult for the reviewer
to make a determination on data reliability, an attempt should be made
to address the point.
Analyst Qualifications -
The findings of an environmental impact statement may be
inaccurate if they are produced by individuals unqualified to speak
with authority on the area in question. The reviewer should examine
an impact statement to determine whether the appropriate breadth and
depth of disciplinary skills is represented on the project team to justify
the assertions made in a statement.
Magnitude vs. Importance -
Impact significance is not necessarily directly related to
impact size. Unique site and regional characteristics are major
determinants of impact significance not necessarily automatically
reflected in objective measures of impact magnitude. Professional
judgments and personal values may also result in differing significance
interpretations being placed upon impacts of the same magnitude. An
impact statement, therefore, should explicitly differentiate between
purely objective quantitative measurements of impacts and evaluative
statements of impact significance.
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Evaluation Documentation -
The environmental impacts identified in impact statements are
never all of equal importance. Some evaluation, including subjective
judgments, is always required to identify those impacts which are key.
The accuracy of impact statements should be reviewed to discover the
basis of such evaluation. This review may indicate a consistent and
obvious bias or it may fail to indicate any consistent basis for
evaluation. An adequate impact statement in contrast, explicitly states
the viewpoints or criteria upon which subjective evaluations are based.
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SECTION VII
A REVIEW OF ENVIRONMENTAL IMPACT
ASSESSMENT METHODOLOGIES
Environmental impact analysis, as required by the National Environ-
mental Policy Act of 1969 (NEPA), is more art than science. There are no uni-
versally applicable procedures for conducting an adequate analysis. There are,
however, a wide variety of assessment tools and even comprehensive methodologies
that may make preparation of an environmental statement a less formidable and
more meaningful task. This section describes and critically analyzes 17 of
these tools and offers suggestions on choosing those tools or methodologies
which may apply to the specifics of a particular environmental assessment
situation.
In only a few cases are the tools discussed full-blown methodologies
developed specifically for impact statement preparation. More commonly, they
are more limited ideas borrowed from other fields with potential application
to NEPA environmental assessments. None of these tools has been widely applied
as yet in actual impact statements; indeed, many have never been so used.
This discussion is not intended as a step-by-step "cookbook" to
the use of these tools; very rarely would any of them be directly applicable
to any specific situation without modification. Instead, key ideas that one
may find useful are discussed and the tools are described in sufficient detail
to help the reader identify those which he or she might wish to examine
more fully.
CHOOSING A METHODOLOGY
•
There is no single "best" methodology for environmental impact
assessment. Characteristics of a methodology such as types of impacts or
projects covered and resources required may be virtues in one instance,
vices in another. Only the user can determine which tools may best fit a
specific task. In selecting the most appropriate tools the following key
considerations may be useful:
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1. Use. Is the analysis primarily a decision or an information
document? (A decison document is vital to determining the best course
of action, an information document functions primarily to reveal the
implications of a single, clearly best choice.) A decision document
analysis will generally require greater emphasis on the identification of
key issues, on quantification, and on direct comparison of alternatives.
An information document requires a more comprehensive analysis concentrating
on interpreting the significance of a broader spectrum of possible impacts.
2. Alternatives. Are alternatives fundamentally or incrementally
different? If differences are fundamental, such as preventing flood
damage by levee construction as opposed to flood plain zoning, for example,
then impact significance can better be measured against some absolute
standard than by direct comparison of alternatives since impacts will differ
in kind as well as size. Fundamentally and incrementally different alter-
native sets require different levels of analysis to discriminate between
alternatives, in that incrementally different alternatives require a greater
degree of quantification.
3. Public Involvement. Does the anticipated role of the public
in the analysis involve substantive preparation, token review, or vital
review? The first two roles allow use of more complex techniques such as
computer or statistical analysis that might be difficult to explain to a
previously uninvolved but highly concerned public. A substantive prepara-
tion role will also allow a greater degree of quantification or weighting
of impact significance through the direct incorporation of public values.
4. Resources. How much time, skill, money, data, and computer
facilities are available? Generally, more quantitative analyses require
more of everything.
5. Familiarity. How familiar is the analyst with both the type
of action contemplated and the physical site? Greater familiarity will im-
prove the validity of a more subjective analysis of impact significance.
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6. Issue Significance. How big is the issue in terms of contro-
versy and scope? All other things being equal, the bigger the issue the
greater the need for explicitness, quantification, and identification of
key issues and the less appropriate become arbitrary significance weights or
specific formulas for trading off one type of impact (e.g., environmental)
against another type (e.g., economic).
7. Administrative Constraints. Are choices limited by agency
procedural or format requirements? Specific agency policy or guidelines
may rule out some tools by specifying the range of impacts to be addressed,
the need for analysing trade-offs, or the time frame of analysis.
CATEGORIZING METHODOLOGIES
The various methodologies examined can be divided into five types,
based on the way impacts are identified:
(1) Ad hoc; These methodologies provide minimal
guidance to impact assessment beyond suggesting
broad areas of possible impacts (e.g., impacts
on flora and fauna, impacts on lakes, forests,
etc), rather than defining specific parameters
to be investigated.
(2) Over lays: These methodologies rely on a set
of maps of environmental characteristics
(physical, social, ecological, aesthetic)
for a project area. These maps are overlaid to
produce a composite characterization of the
regional environment. Impacts are identified
by noting the impacted environmental charac-
teristics lying within the project boundaries.
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(3) Checklists; These methodologies present a specific
list of environmental parameters to be investigated
for possible impacts but do not require the estab-
lishment of direct cause-effect links to project
activities. They may or may not include guidelines
on how parameter data are to be measured and interpreted
(4) Matrices; These methodologies incorporate a list of
project activities in addition to a checklist of po-
tentially impacted environmental characteristics.
These two lists are related in a matrix which identifies
cause-effect relationships between specific activities
and impacts. Matrix methodologies may specify which
actions impact which environmental characteristics or
may simply list the range of possible actions and
characteristics in an open matrix to be completed by
the analyst.
(5) Networ ks; These methodologies work from a list of
project activities to establish cause-condition-effect
networks. They are an attempt to recognize that a
series of impacts may be triggered by a project action.
These approaches generally define a set of possible
networks and allow the user to identify impacts by
selecting and tracing out the appropriate project
actions.
REVIEW CRITERIA
To serve the purposes of the National Environmental Policy Act of
1969 (NEPA), an environmental impact assessment must effectively deal with
four key problems:
• Impact identification
• Impact measurement
• Impact interpretation
• Impact communication to information users.
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Based upon experience with impact assessments to date, a set
of 20 criteria for methodology evaluation can be defined covering these
four key problems. These are:
• Impact Identification
1. Comprehensiveness. An impact methodology should
address a full range of impacts including:
ecological, physical-chemical pollution, social-
cultural, aesthetic, resource supplies, induced
growth, induced population or wealth redistri-
butions, and induced energy or land use patterns.
2. Specificity. A methodology should identify
specific parameters (subcategories of impact
types) to be examined.
3. Isolate Project Impacts. A methodology should
require and suggest methods for identifying project
impacts as distinct from future environmental
changes produced by other causes.
4e Timing and Duration. A methodology should require
and suggest methods for identifying the timing
(construction phase vs. short-term operation
vs. long-term operation phase) and the duration
of impacts.
5. Data Sources. A methodology should require iden-
tification of the sources of data used to identify
impacts.(Data sources should also be listed for
impact measurement and interpretation.)
• Impact Measurement
6. Explicit Indicators. A methodology should suggest
specific measurable indicators to be used to
quantify impacts on parameters.
7. Magnitude. A methodology should require and pro-
vide for the measurement of impact magnitude as
distinct from impact significance.
8. Objectivity. A methodology should emphasize objec-
tive rather than subjective impact measurements.
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• Impact Interpretation
9. Significance. A methodology should require explicit
assessment of the significance of measured impacts
on a local, regional, and national scale.
10. Explicit Criteria. A methodology should require
that the criteria and assumptions employed to
determine impact significance be stated.
11. Uncertainty. A methodology should require an
assessment of the uncertainty or degree of confi-
dence in impact projections made.
12. Risk. A methodology should require identification
of any impacts of low probability but high potential
damage or loss.
13. Alternatives Comparison. A methodology should
provide a specific method for the comparison of
alternatives, including the no-project alternative.
14. Aggregation. A methodology may provide a mechanism
for aggregating impacts into a net total or composite
estimate. If aggregation is provided for, specific
weighting criteria or processes to be used should be
identified. The appropriate degree of aggregation
is a hotly debated issue on which no judgment has
been made in this review.
15. Public Involvement. A methodology should require
and suggest a mechanism for public involvement in
the interpretation of impact significance.
• Impact Communication
16. Affected Parties. A methodology should require
and suggest a mechanism for linking impacts to
the specific affected geographical or social groups.
17. Setting Description. A methodology should require
a description of the project setting to aid state-
ment users in developing an adequate overall
perspective.
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18. Summary Format. A methodology should provide a
format for presenting in summary form, the results
of the analysis.
19. Key Issues. A methodology should provide a format
for highlighting key issues and impacts identified
in the analysis.
20. NEPA Compliance. A methodology should provide
guidelines for summarizing results in terms of the
specific points required by NEPA and subsequent CEQ
guidelines.
In addition to the above "content" criteria, methodological tools
should be evaluated in terms of their resource requirements, replicability,
and flexibility. The following considerations, used in arriving at the
generalized ratings for these characteristics (shown in Table 14), may be
useful in considering the appropriateness of tools. Important specific
requirements and limitations are discussed for each tool reviewed in the
methodology descriptions below.
• Resource Requirements
1. Data Requirements. Does the methodology require
data that is presently available at low retrieval
costs?
2. Manpower Requirements. What special skills are
required?
3. Time. How much time is required to learn to use
and/or actually apply the methodology?
4. Costs. How do costs of using a methodology compare
to costs using other tools?
5. Technologies. Are any specific technologies (e.g.,
computerization) required to use a methodology?
• Replicability
1. Ambiguity. What is the relative degree of ambiguity
in the methodology?
193
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2. Analyst Bias. To what degree will different impact
analysts using the methodology tend to produce
widely different results?
• Flexibility
1. Scale Flexibility. How applicable is the methodology
to projects of widely different scale?
2. Range. For how broad a range of project or impact
types is the methodology useful in its present form?
3. Adaptability. How readily can the methodology be
modified to fit project situations other than those
for which it was designed?
Methodologies were rated for their degree of compliance with
the 20 content criteria, their level of resource requirements, and their
replicability-flexibility limitations as follows:
• = Substantial compliance, low resource needs, or few
replicability-flexibility limitations
• = Partial compliance, moderate resource needs, or
moderate limitations
o = No or minimal compliance, high resource needs, or
major limitations.
The resulting ratings, shown in Table 14, should be regarded as
subjective judgments only, but do provide a shorthand characterization
of the important features of the methodological tools examined.
METHODOLOGY DESCRIPTIONS
The 17 methodologies or tools discussed were examined via the above
set of review criteria with results summarized in Table 14 on page 192. A brief
description of each methodology follows, discussing the following points.
• The methodology type
• The general approach used
• The range of actions or project types for
which the methodology may be applicable
• The comprehensiveness of the methodology
in terms of the range of impacts addressed
195
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• The resources required (data, manpower, time, etc).
• The limitations of the methodology (replicability,
ambiguity, flexibility)
• Key ideas or particularly useful concepts offered
• Other major strengths and weaknesses as identified
by the review criteria.
Because of the brevity and subjectivity of these characterizations,
they should not be considered as adequate critiques of the tools examined.
They may instead serve as a useful introduction to the range of techniques
now evolving.
1. Adkins, William G. and Dock Burke Jr., Interim Report;
Social, Economic, and Environmental Factors in Highway
Decision Making, research conducted for the Texas
Highway Department in cooperation with the U.S.
Department of Transportation, Federal Highway Admin-
istration: College Station, Texas; Texas Transportation
Institute, Texas A&M University (October 1971).
The Adkins methodology is a checklist using a +5 to -5 rating system
for evaluating impacts but providing no guidelines for measuring impacts.
The approach was developed to deal specifically with the evaluation of
highway route alternatives. Because the bulk of parameters used relate
directly to highway transportation, the approach is not readily adaptable
to other types of projects.
The parameters used are broken down into categories of transportation,
environmental, sociological, and economic impact. Environmental parameters
are generally deficient in ecological considerations. Social parameters
emphasize community facilities and services.
Route alternatives are scored +5 to -5 in comparison to the present
state of the project area, not the expected future state without the project.
Since the approach uses only subjective relative estimations of impacts, the
data, manpower, and cost requirements are very flexible. Reliance on sub-
jective ratings without guidelines for such ratings greatly reduces the
replicability of analysis and generally limits the valid use of the approach
to a case-by-case comparison of alternatives only.
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The detailed listing of social and, to a lesser extent, economic
parameters may be helpful for identifying and cataloging impacts in other
types of projects. An interesting feature of possible value to other
analyses using relative rating systems is the practice of summarizing the
number as well as the magnitude of plus and minus ratings for each impact
category. The number of pluses and minuses may be a more reliable indicator
for alternative comparison since it is less subject to the arbitrariness
of subjective weighting. These summarizations are additive and thus
implicitly weigh all impacts equally.
2. Dee, Norbert, et al, Environmental Evaluation System
For Water Resources Planning, report to the U.S.
Bureau of Reclamation, Columbus, Ohio: Battelle
Memorial Institute (January 1972).
This methodology is a checklist procedure emphasizing quantita-
tive impact assessment. It was designed for major water resource projects
but most parameters used are also appropriate for other types of projects.
Seventy-eight specific environmental parameters are defined within the four
categories of ecology, environmental pollution, aesthetics, and human
interest. The approach does not deal with economic or secondary impacts
and social impacts are only partially covered within the human interest
category.
Impacts are measured via specific indicators and formulas defined
for each parameter. Parameter measurements are converted to a common base
of "environmental quality units" through specified graphs or value functions.
Impacts can be aggregated using a set of preassigned weights.
The resource requirements are rather high, particularly data
requirements. These requirements probably restrict the use of the approach
to major project assessments.
The approach emphasizes explicit procedures for impact measurement
and evaluation and should therefore produce highly replicable results. Both
spatial and temporal aspects of impacts are noted and explicitly weighted
in the assessment. Public participation, uncertainty, and risk concepts
are not dealt with. An important idea of the approach is the highlighting
of key impacts via a "red flag" system.
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3. Dee, Herbert, et al., Planning Methodology for Water
Quality Management; Environmental Evaluation System,
Columbus, Ohio: Battelle Memorial Institute (July 1973).
This unique methodology of impact assessment defies ready classi-
fication since it contains elements of checklist, matrix, and network
approaches. Areas of possible impacts are defined by a hierarchical system
of four categories (ecology, physical/chemical, aesthetic, social), 19
components and 64 parameters. An interaction matrix is presented to indicate
which activities associated with water quality treatment projects generally
impact which parameters. The range of parameters used is comprehensive,
excluding only economic variables.
Impact measurement incorporates two important elements. A set
of "ranges" is specified for each parameter to express impact magnitude on
a scale from zero to one. The ranges assigned to each parameter within a
component are then combined by means of an "environmental assessment tree"
into a summary environmental impact score for that component. The signi-
ficance of impacts on each component is quantified by a set of assigned
weights. A net impact can be obtained for any alternative by multiplying
each component score by its weight factor and summing across components.
The key features of the methodology are its comprehensiveness,
its explicitness in defining procedures for impact identification and
scoring, and its flexibility in allowing use of best available data.
Sections of the report explain the several uses of the methodology
in an overall planning effort and discuss means of public participation.
The data, time, and cost requirements of the methodology when used for impact
assessment are moderate, though a small amount of training would be required
to familiarize users with the techniques used.
Because of its explicitness, the methodology possesses only minor
ambiguities and should be highly replicable. Because the environmental
assessment trees are developed specifically for water treatment facilities,
the methodology cannot be adapted to other types of projects without re-
constructing the trees though the parameters could be useful as a simple
checklist.
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One potentially significant obstacle to use of the approach is
the difficulty of explaining the procedures to the public. Regardless
of the validity of the "trees", they are unfamiliar devices developed by
highly specialized multivariant analysis techniques and public acceptance
of conclusions reached by their use may be low.
4. Institute of Ecology, University of Georgia, "Optimum
Pathway Matrix Analysis Approach to the Environmental
Decision Making Process: Test case: Relative Impact
of Proposed Highway Alternatives", Athens, Georgia:
University of Georgia, Institute of Ecology (1971)
fmimeographed).
The "Georgia"methodology incorporates a checklist of 56
environmental components. Measurable indicators are specified for each
component. The actual values of alternative plan impacts on a component
are normalized and expressed as a decimal of the largest impact (on that
one component). These normalized values are multiplied by a subjectively
determined weighting factor. This factor is the sum of one times a weight
for "initial" effects plus ten times a weight for "long-term" effects.
The methodology is used to evaluate highway project alternatives
and the components listed are not suitable for other types of projects.
A wide range of impact types are analyzed including land use, social, aes-
thetics, and economic impacts.
The lower replicability of the analysis produced by using sub-
jectively determined weighting factors is compensated for by conducting
several passes at the analysis, and incorporating randomly generated error
variation in both actual measurements and weights. This procedure provides
a basis for testing the significance of differences in total impact scores
between alternatives.
The procedures for normalizing or scaling measured impacts to
obtain commensurability, and testing of significant differences between
alternatives are notable features of potential value to other impact
analyses and methodologies. These ideas may be useful whenever several
project alternatives can be identified and compared.
The Georgia methodology places rather high resource demands on
the user since computerization is necessary to generate random errors and
make the large number of repetitive calculations.
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5. Krauskopf, Thomas M., and Dennis C. Bunde, "Evalua-
tion of Environmental Impact Through a Computer
Modelling Process", Environmental Impact Analysis;
Philosophy and Methods, (eds.) Robert Ditton and
Thomas Goodale, Madison, Wisconsin: University of
Wisconsin Sea Grant Program (1972), pp. 107-125.
This methodology employs an overlay technique via computer
mapping. Data on a large number of environmental characteristics are
collected and stored in the computer on a grid system of 1 km square cells.
Highway route alternatives can either be evaluated by the computer (by
noting the impacts on intersected cells) or new alternatives may be
generated via a program identifying the route of least impact.
The environmental characteristics used are rather comprehensive,
particularly as regards land use and physiographic characteristics. Though
the methodology was developed and applied to a highway setting, it is
adaptable, with relatively small changes in characteristics examined, to
other project types with geographically well defined and concentrated im-
pacts. Because the approach requires considerable amounts of data on the
project region, it is not practical for the analysis of programs of broad
geographical scope. The high manpower-skill, money, and computer technology
requirements of the approach may also make it impractical at the present
time for any but major projects, or in situations where a statewide, computerized
data base exists (New York, Minnesota, Iowa, etc).
The estimation of impact importance is done through the specification
of subjective weights. Because the approach is computerized, the effects
of several alternative weighting schemes can be readily analyzed.
The methodology is attractive on several viewpoints. It allows
a demonstration of which weighted characteristics are central to a particular
alternative route; it presents a readily understandable graphic representation
of impacts and alternatives; it easily handles several subjective weighting
systems; the incremental costs of considering or generating additional
alternatives is low; and it fits well with developing regional and statewide
data bank systems.
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The mechanics of the approach—how impacts are measured and
combined—are not readily apparent from the reference cited. Considerable
training beyond the information available in this reference would be
required to use the approach.
6. Leopold, Luna B., et al., A Procedure for Evaluating
Environmental Impact, Geological Survey Circular 645,
Washington: Government Printing Office (1971).
This is an open-cell matrix approach identifying 100 project
activities and 88 environmental characteristics or conditions. For each
action involved in a project, the analyst evaluates the impact on every
impacted environmental characteristic in terms of impact magnitude and
significance. These evaluations are subjectively determined by the analyst.
Ecological and physical-chemical impacts are treated comprehensively,
social and indirect impacts are less well handled, and economic and
secondary impacts are not addressed.
Because the assessments made are subjective, resource requirements
of the approach are very flexible. The approach was not developed in re-
ference to any specific type of project and may be broadly applied with
some alterations.
Guidelines for use of the approach are minimal and several
important ambiguities are likely in the definition and separation of impacts.
The reliance on subjective judgment, again without guidelines, reduces the
replicability of the approach.
The approach is chiefly valuable as a means of identifying project
impacts and as a display format for communicating results of an analysis.
7. Arthur D. Little, Inc., Transportation and Environment;
Synthesis for Action: Impact of National Environmental
Policy Act of 1969 on the Department of Transportation,
Vol. 3, Options for Environmental Management, prepared
for Office of the Secretary, Department of Transportation
(July 1971).
This is less a complete methodology than an overview discussion
of the kinds of impacts that may be expected to occur from highway projects
and the measurement techniques that may be available to handle some of
them. A quite comprehensive list of impact types and the stages of project
development at which each may occur are presented. As broad categories,
the impact types identified are useful for other projects as well as for
highways. 2Q1
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The approach suggests the separate consideration of an impact's
amount, effect (public response), and value. Some suggestions are offered
for measuring the amount of impact within each of seven general categories:
noise, air quality, water quality, soil erosion, ecologic, economic, and
sociopolitical impacts.
Five possible approaches to the handling of impact significance
are presented. Three of these are "passive" (requiring no agency action)
such as "reliance on the emergence of controversy". The other two involve
the use of crude subjective weighting scales. No specific suggestions are
made for the aggregation of impacts either within or between categories.
In general, the reference cited is a useful discussion of some
of the important issues of impact analysis, particularly as they apply
to transportation projects, but does not present a complete analytical
technique.
8. McHarg, Ian., "A Comprehensive Highway Route-
Selection Method", Highway Research Record,
Number 246, 1968, pp. 1-15, or McHarg, Design
With Nature, Garden City, New York: Natural
History Press, 1969, pp. 31-41.
The McHarg approach is a system employing transparencies of
environmental characteristics overlaid on a regional base map. Eleven
to sixteen environmental and land use characteristics are mapped. The
maps represent three levels of the characteristics, based upon "compatibility
with the highway". These references do not indicate how this compatibility
is to be determined but available documentation is cited.
This approach is basically an earlier, noncomputerized version
of the ideas presented in the Krauskopf reference. Its basic value is as
a method for screening alternative project sites or routes. Within this
limited use, it is applicable to a variety of project types.
Limitations of the approach include its inability to quantify
as well as identify possible impacts and its implicit weighting of all
characteristics mapped.
Resource requirements of the McHarg approach are somewhat less
demanding, in terms of data, than those of the Krauskopf approach because
information is not directly quantified, only categorized into three levels.
High degrees of skill and training are required, however, to prepare the
map overlays.
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The approach seems most useful as a "first cut method" of
identifying and sifting out alternative project sites, preliminary to
detailed impact analysis.
9. Moore, John L., et al., A Methodology for Evaluating
Manufacturing Environmental Impact Statements for
Delaware's Coastal Zone, Report to the State of
Delaware, Columbus, Ohio: Battelle Memorial Institute
(June 1973).
This approach was not designed as a method for impact analysis
but its principles could be adapted for such use. It employs a network
approach, linking a list of manufacturing-related activities-to potential
environmental alterations-to major environmental effects, and finally-to
human uses affected. The primary strength of the set of linked matrices
is their utility in displaying cause-condition-effect networks and tracing
out secondary impact chains.
Such networks are useful primarily for identifying impacts and
the issues of impact magnitude and significance are addressed only in
terms of high, moderate, low, or negligible damage. As a result of these
subjective evaluations the approach would have low replicability as an
assessment technique. For such a use, guidelines would likely need to be
proposed to define the evaluation categories.
The approach incorporates indicators especially tailored to
manufacturing facilities in a coastal zone though most indicators would
also be pertinent to other types of projects.
The approach would perhaps be valuable as a visual summary of
an impact analysis for communication to the public and decision makers.
10. Central New York Regional Planning and Development
Board, Environmental Resources Management, prepared
for Department of HUD (October 1972) (available
through the National Technical Information Service
PB 217-517).
This methodology employs a matrix approach to assess in simple
terms the major and minor, direct and indirect impacts of certain water
related construction activities. It is designed primarily to measure only
the physical impacts of water resource projects in a watershed, and is
based on an identification of the specific, small-scale component activities
that are included in any project. Restricted to physical impacts on nine
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different types of watershed areas (e.g., wetlands) and fourteen types
of activities (e.g., tree removal), the procedure indicates four possible
levels of impact-receptor interactions (major direct through minor indirect).
Low to moderate resources in terms of time, money, or personnel are required
for the methodology, due principally to its simple way of quantification
(major versus minor impact). However, the procedure is severely limited in
its ability to compare different projects or the magnitude of different
impacts. There is no spatial or temporal differentiation, hence the full
range of impacts cannot be assessed. Impact uncertainty and high damage-
low probability impacts are also not considered. Only two levels of the
magnitude of an impact are identified while the importance of the impacts
are not assessed, resulting in moderate replicability. The lack of objec-
tive evaluation criteria may produce ambiguous results. NEPA requirements
for impact assessments are not directly met by this procedure.
The value of this methodology is less in the actual assessment
of the quantitative impacts of a potential project than in a "capability
rating system" which determines recommended development policies based on
existing land characteristics. Thus, guidelines on desirable and undesirable
activities with respect to the nine types of watershed areas are used to
map a region in terms of the optimum land use plan. The actual mapping
procedure is not described, however, and hence that aspect of the impact
assessment methodology cannot be evaluated here.
11. Smith, William L., "Quantifying the Environmental
Impact of Transportation Systems" , Van Doren-
Hazard-Stallings-Schnacke, Topeka, Kansas (undated)
(mimeographed).
The Smith approach, as developed for highway route selection,
is a checklist system based on the concepts of probability and supply-
demand. The approach attempts to identify the alternative with least
social cost to environmental resources and maximum social benefit to
system resources. Environmental resources elements are listed as:
agriculture, wildlife conservation, interference, noise, physical features,
and replacement. System resources elements are listed as: aesthetics,
cost, mode interface, and travel desires. For each element, categories
are defined and used to classify zones of the project area. Numerical
probabilities of supply and of demand are then assigned to each zone for
each element. These are multiplied to produce a "probability of least
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social cost" (or maximum social benefit). These least social cost
probabilities are then multiplied across the elements to produce a
total for the route alternative under examination.
The approach is tailored and perhaps limited to project
situations requiring comparison of siting alternatives. The range
of environmental factors examined is very limited, but presumably
could be expanded to cover more adequately ecological, pollution, and
social considerations.
Since procedures for determining supply and demand probabilities
are not described, it is difficult to anticipate the amounts of data, man-
power and money required to use the approach. The primary limitations of
this methodology are difficulties inherent in assigning probabilities,
particularly demand probabilities, and the implicitly equal weightings
assigned to each element analyzed when multiplying to yield an aggregate
score for an alternative.
12. Sorensen, Jens, A Framework for Identification and
Control of Resource Degradation and Conflict in
the Multiple Use of the Coastal Zone, Berkeley:
University of California, Department of Landscape
Agriculture (1971), and Sorensen and James E. Pepper,
Procedures for Regional Clearinghouse Review of
Environmental Impact Statements — Phase Two, report
to the Association of Bay Area Governments (April
1973).
These two publications present a network approach usable for
environmental impact analysis. The approach is not a full methodology but
rather a guide to the identification of impacts. Several potential uses
of the California coastal zone are examined through networks relating
uses-to causal factors (project activities)-to first order condition
changes-to second and third order condition changes, and finally-to
effects. The major strength of the approach is its ability to identify
the pathways by which both primary and secondary environmental impacts
are produced.
The second reference also indicates types of data relevant to
each effect identified, though no specific measurable indicators are
suggested. In this reference some general criteria for identifying projects
of regional significance are suggested, based on project size and types of
impacts generated, particularly land use impacts.
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Because the preparation of the required detailed networks is
a major undertaking, the approach is presently limited to some commercial,
residential, and transportation uses of the California coastal zone for
which networks have been prepared. An agency wishing to use the approach
in other circumstances might develop the appropriate networks for reference
in subsequent environmental impact assessments.
13. Stover, Lloyd V., Environmental Impact Assessment;
A Procedure, Miami, Florida: Sanders and Thomas,
Inc. (1972).
This methodology is a checklist procedure for a general
quantitative evaluation of environmental impacts from development activities.
The type and range of these activities is not specified, but is believed
to be comprehensive. Fifty different impact parameters are sufficient to
include most possible effects, and thereby allow much flexibility. Sub-
parameters indicate specific impacts, but there is no indication of how
the individual measures are aggregated into a single parameter value. While
spatial differences in impacts are not indicated, both initial and future
impacts are included and explicitly compared. Resource requirements are
moderate to heavy, especially in terms of an interdisciplinary personnel
team which grows as more subparameters are included, requiring additional
expertise in specific areas. However, the actual measurements are not
based on specific criteria and are only partially quantitative, with seven
possible values ranging from an extremely beneficial impact to an extremely
detrimental one. Therefore, there is potential for ambiguous and subjective
results, with only moderate replicability. Impact areas are implicitly
assumed to be of equal importance. A specific methodology is mentioned
for choosing the optimum alternative in terms of benefits and adverse
effects. The procedure for alternatives comparison may be the most
interesting aspect of the procedure, with results given in terms of the
proportional significance of an impact vis-a-vis other potential alterna-
tives. There is no explicit mention of either public involvement in the
process, or environmental risks.
The impact assessment procedure is presented as only one step
in a total evaluation scheme which includes concepts of dynamic ecological
stability and other ideas. An actual description of the entire process
is not included, however.
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14. Multiagency Task Force, "Guidelines for Implementing
Principles and Standards for Multiobjective Planning
of Water Resources", Review Draft, Washington: U.S.
Bureau of Reclamation (1972).
The Task Force approach is an attempt to coordinate features
of the Water Resources Council's Proposed Principles and Standards for
Planning Water and Related Land Resources with requirements of NEPA. It
develops a checklist of environmental components and categories organized
in the same manner as the WEC Guidelines. The categories of potential
impacts examined deal comprehensively with biological, physical, cultural,
and historical resources, and pollution factors but do not treat social or
economic impacts. Impacts are measured in quantitative terms where possible
and also rated subjectively on "quality" and "human influence". In
addition, uniqueness and irreversibility considerations are included where
appropriate. Several suggestions for summary tables and bar graphs are
offered as communications aids.
The approach is general enough to have wide applicability to
various types of projects, though its impact categories are perhaps
better tailored to rural than urban environments. No specific data or
other resources are required to conduct an analysis, though an interdisci-
plinary project team is specified to assign the subjective weightings.
Since quality, human influence, uniqueness, and irreversibilities are all
subjectively rated using general considerations only, results produced
by the approach may be highly variable. Significant ambiguities include
a generally inadequate explanation of how human influence impacts are to
be rated and interpreted.
Key ideas incorporated in the approach include explicit identifi-
cation of the without-project environment as distinct from present conditions,
and use of uniqueness rating system for evaluating quality and human
influence (worst known, average, best known, etc). The methodology is
unique among those examined in not labeling impacts as environmental
benefits or costs but only as impacts to be valued by others. The approach
also argues against the aggregation of impacts.
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15. Tulsa District, U.S. Army Corps of Engineers,
Matrix Analysis of Alternatives for Water Resource
Development, draft technical paper (July 31, 1972).
Despite the title, this methodology can be considered a checklist
under the definitions used here since, though a display matrix is used to
summarize and compare the impacts of project alternatives, impacts are
not linked to specific project actions. The approach was developed to
deal specifically with reservoir construction projects but could be readily
adapted to other project types.
Potential impacts are identified within three broad objectives:
environmental quality, human life quality, and economics. For each impact
type identified, a series of factors are described, indicating possible
measurable indicators. Impact magnitude is not measured in physical units
but by a relative impact system. This system assigns the future state of
an environmental characteristic without the project a score of zero; then
assigns the project alternative possessing the greatest impact on that
characteristic a score of +5 (for positive impact), or -5 (for negative
impact). All other alternatives are assigned scores between 0 and 5 by
comparison. The raw scores thus obtained are multiplied by weights
determined subjectively by the impact analysis team.
Like the Georgia approach, the Tulsa methodology tests for the
significance of differences between alternatives by introducing error
factors and conducting repeated runs. The statistical manipulations
are different from those used in the Georgia approach, however, and con-
sidered by the Corps' writers to be more valid.
Resource requirements of the Tulsa methodology are variable.
Since specific types or levels of data are not required, data needs are
quite flexible. The consideration of error, however, requires specific
skills and computer facilities.
The major limitations of the approach, aside from the required
computerization, are the lack of clear guidelines on exactly how to
measure impacts and the lack of guidance on how the future no-project
state is to be defined and described in the analysis. Without careful
description of the assumptions made, replicability of analyses made using
the approach may be low since only relative measures are used. Since all
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measurements are relative, it may also be difficult in some cases to deal
with impacts that are not clearly definable as gains or losses.
The key ideas of wider interest incorporated in the Tulsa
approach include reliance on relative rather than absolute impact
measurement, statistical tests of significance with error introduction,
and specific use of the no-project condition, as a base line for impact
evaluation.
16. Walton, L. Ellis, Jr., and James E. Lewis, A Manual
for Conducting Environmental Impact Studies, Virginia
Highway Research Council (January 1971) (available
through the National Technical Information Service
PB-210 222).
The Walton methodology is a checklist, unique in its almost
total reliance on social impact categories and strong public participation.
The approach was developed for the evaluation of highway alternatives and
identifies different impact analysis procedures for the conceptual,
corridor, and design states of highway planning. All impacts are measured
by either their dollar value or a weighted function of the number of persons
affected. (The weights used are to be determined subjectively by the study
team.) The basis for most measurements is a personal interview with a
representative of each facility or service impacted.
Resource requirements for such a technique are highly sensitive
to project scale. The extensive interviewing required may make the approach
impractical for many medium-size or large projects because agencies pre-
paring impact statements seldom have the necessary manpower or the money
to contract for such extensive interviewing.
Analyses produced by the approach may have very poor replicability
due to the lack of specific data used and the criticality of the decision
regarding boundaries of the analysis since many impacts are measured in
numbers of people affected. There is also no means of systematically
taking into account the extent to which these people are affected.
The key ideas of broader interest put forth by the approach
are the use of only social impacts without direct consideration of other
impacts (pollution, ecology, etc), the heavy dependence on public in-
volvement and specific suggestions on how the public may be involved,
and the recognition of the need for different analyses of different stages
of project development.
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17. Western Systems Coordinating Council, Environmental
Committee, Environmental Guidelines (1971). (Mr.
Robert Coe, Southern California Electric Company,
Environmental Committee Chairman.)
The Environmental Guidelines are intended primarily as a planning
tool for siting power generation and transmission facilities. However,
they address many of the concerns of environmental impact analysis and
have been used in the preparation of impact statements. Viewed as an
impact assessment methodology, the approach is an ad hoc procedure,
suggesting general areas and types of impacts but not listing specific
parameters to examine.
The approach considers a range of pollution, ecological,
economic (business economics), and social impacts but does not address
secondary impacts such as induced growth, or energy use patterns. The
format of the approach is an outline of considerations important to the
selection of sites for each of several types of facilities — e.g.,
thermal generating plants, transmission lines, hydroelectric and pumped
storage, and substations. An additional section offers suggestions for
a public information program.
Since the approach does not suggest specific means of measuring
or evaluating impacts no particular types of data or resources are required.
The application of this approach is limited to the siting of electric
power facilities with little carry over to other types of projects.
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ASSESSMENT METHODOLOGIES IN IMPACT STATEMENTS
As a part of the review of methodologies for environmental impact
assessment, 67 statements were examined for the methodologies used. The
statements were distributed as follows (see full listing at the e~d of the
section): Bureau of Reclamation 15, Army Corps of Engineers 22, Tennessee
Valley Authority 14, Soil Conservation Service 13, and Federal Pover Con-
mission 3.
None of the statements examined employed any of the 17 method-
ologies reviewed, nor did they employ other identifiable systems of impact
assessment. Without exception, the statements utilized techniques that
must be characterized as ad hoc, or less frequently, simple check lists.
These approaches characteristically addressed the four basic elements of
impact assessment as follows.
Impact Identification
Impacts were generally identified solely from the perceptions of
the agency staff preparing the statement, with general guidance fr:n agency
procedural guidelines. There was no evidence of any attempt to enploy
either exhaustive lists of potentially impacted environmental features or
lists of impacts typically associated with specific types of projects. As
a result, the statements exhibited great variability in the types cf
impacts dealt with. Impacts on hydrologic systems, wildlife, water and
air quality were nearly always covered. Impacts on ecological systems
characteristics (diversity, productivity), land use, induced growth, eco-
nomics, social-cultural patterns, and all types of secondary impacts were
more rarely addressed.
Impact Measurement
The only generalization possible regarding impact measurement
techniques employed in the statements reviewed is that impacts were
211
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universally expressed in terms of available data only. No evidence of
the collection of any original data to assess environmental impacts was
seen. As a result, impacts were expressed at greatly varying levels of
objectivity and precision, from "may affect air quality" to detailed
inventories of species population changes expected and acres of land
use shifts. Generally, impact magnitudes were not separated from signifi-
cance.
Impact Evaluation
No systematic means of reporting impact significance was found
in the statements examined. Most estimates of significance were highly
subjective conclusions of the agency staff. The only commonly employed
aspect of significance used was "uniqueness", occasionally employed in
discussing impacts on wildlife, historical and archeological features,
and aesthetics. The statements exhibited no consistent frame of reference
(local, regional, national) in assessing impact significance and no
systematic consideration of the timing of effects.
In contrast to the heavy emphasis placed on aggregating impacts
into net scores exhibited by several of the methodologies examined, the
67 impact statements universally ignored aggregation. Impacts were simply
listed in paragraph or outline form, though such listing became long and
complex for some major projects such as the Central Arizona Project.
Impact Communication
Attempts to summarize and communicate conclusions were generally
limited to a mechanical adherence to the points of NEPA, and a one-page
statement summary. In only one case (Bonneville Unit, Central Utah Project,
BuRec) were simple summary comparisons of alternatives prepared. No state-
ment included a point-by-point comparison of the preferred project plan and
alternatives. Impacts were likewise never summarized in terras of affected
parties.
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REFERENCES
Adkins, W.G. and Dock Burke, Jr. October, 1971. Interim report: social,
economic, and environmental factors in highway decision making.
Research conducted for the Texas Highway Department in cooperation with
the U.S. Department of Transportation, Federal Highway Administration:
College Station, Texas. Texas Transportation Institute. Texas A&M
University.
Dee, N., et.al. January, 1972. Environmental evaluation system for water
resources planning. Report to the U.S. Bureau of Reclamation. Columbus,
Ohio. Battelle Memorial Institute.
. July, 1973. Planning methodology for water quality management:
environmental evaluation system. Columbus, Ohio.
Institute of Ecology, University of Georgia. 1971. Optimum pathway matrix
analysis approach to the environmental decision making process : test
case: relative impact of proposed highway alternatives. Athens, Georgia.
University of Georgia. Institute of Ecology. (mimeographed)
Krauskopf, T.M. and D. C. Bunde. 1972. Evaluation of environmental impact
through a computer modelling process. Environmental impact analysis:
philosophy and methods. Robert Ditton and Thomas Goodale, eds. Madison,
Wisconsin. University of Wisconsin Sea Grant Program, pp. 107-125.
Leopold, L.B., et.al. 1971. A procedure for evaluating environmental
impact. Geological Survey Circular 645. Washington. Government Printing
Office.
Arthur D. Little, Inc. July, 1971. Transportation and environment: synthesis
for action: impact of National Environmental Policy Act of 1969 on the
Department of Transportation. Vol. 3 Options for environmental management.
Prepared for Office of the Secretary, Department of Transportation.
McHarg, I. 1968. A comprehensive highway route-selection method. Highway
research record. Number 246. pp. 1-15; or McHarg, I. 1969. Design with
nature. Garden City, New York. Natural History Press, pp. 31-41.
Moore, J.L., et.al. June, 1973. A methodology for evaluating manufacturing
environmental impact statements for Delaware's coastal zone. Report to
the State of Delaware. Columbus, Ohio. Battelle Memorial Institute.
Central New York Regional Planning and Development Board. October, 1972.
Environmental resources management. Prepared for Department of HUD.
(available through the National Technical Information Service PB 217-517)
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Smith, W.L. Undated. Quantifying the environmental impact of transportation
systems. Van Doren-Hazard-Stallings-Schnacke. Topeka, Kansas.
Sorensen, J. 1970. A framework for identification and control of resource
degradation and conflict in the multiple use of the coastal zone. Berkeley.
University of California, Department of Landscape Agriculture. And,
Sorensen, J. and J.E. Pepper. April, 1973. Procedures for regional
clearinghouse review of environmental impact statements. Phase two.
Report to the Association of Bay Area Governments.
Stover, L.V. 1972. Environmental impact assessment: a procedure. Miami,
Horida. Sanders and Thomas, Inc.
Multiagency Task Force. December, 1972. Guidelines for implementing
principles and standards for multiobjective planning of water resources.
Review draft. Washington. U.S. Bureau of Reclamation.
Tulsa District, U.S. Army Corps of Engineers. July 31, 1972. Matrix
analysis of alternatives for water resource development. Draft technical
paper.
Walton, L.E., Jr. and J.E. Lewis. January, 1971. A manual for conducting
environmental impact studies. Virginia Highway Research Council.
.(available through the National Technical Information Service PB-210 222)
Western Systems Coordinating Council. Environmental Committee. 1971.
Environmental guidelines. (Mr. Robert Coe, Southern California Electric
Company, Environmental Committee Chairman)
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SECTION VIII
ENVIRONMENTAL IMPACT STATEMENTS REVIEWED
DEPARTMENT OF THE INTERIOR
BUREAU OF RECLAMATION
Department of the Interior, Bureau of Reclamation, "Final
Environmental Impact Statement, Proposed Central Arizona
Project" (September 26, 1972).
Department of the Interior, Bureau of Reclamation, "Draft
Environmental Impact Statement, Granite Reef Aqueduct, Central
Arizona Project, Arizona-New Mexico" (March 1A, 1973).
Department of the Interior, Bureau of Reclamation, "Final
Environmental Impact Statement, Bonneville Unit, Central Utah
Project, Utah" (August 2, 1973).
Department of the Interior, Bureau of Reclamation, "Final
Environmental Impact Statement, Bonneville Unit, Central Utah
Project, Utah", Appendix A: Review Comments (August 2, 1973).
Department of the Interior, Bureau of Reclamation, Regional
Office, Upper Missouri Region, Billings, Montana, "Draft
Environmental Impact Statement, Initial Stage, Garrison Diversion
Unit, Pick-Sloan Missouri Basin Program, North Dakota" (April
5, 1973).
Department of the Interior, Bureau of Reclamation, "Final
Environmental Impact Statement, Tualatin Project, Oregon"
(April, 1972).
Department of the Interior, Bureau of Reclamation, "Final
Environmental Impact Statement, Pueblo Dam and Reservoir,
Fryingpan-Arkansas Project, Colorado" (May, 1972).
Department of the Interior, Bureau of Reclamation, "Final
Environmental Impact Statement, Auburn-Folsom South Unit,
Central Valley Project, California" (November 13, 1972).
Department of the Interior, Bureau of Reclamation, "Final
Environmental Impact Statement, Crystal Dam, Reservoir, and
and Powerplant, Curecanti Unit, Colorado River Storage
Project, Colorado" (December 6, 1971).
Department of the Interior, Bureau of Reclamation, "Supplement
to the Final Environmental Impact Statement, Crystal Dam,
Reservoir, and Powerplant Curecanti Unit, Colorado River
Storage Project, Colorado" (April 30, 1973).
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Department of the Interior, Bureau of Reclamation, "Draft
Environmental Impact Statement, Initial Stage, Oahe Unit,
Pick-Sloan Missouri Basin Program, South Dakota" (August
4, 1972).
Department of the Interior, Bureau of Reclamation, "Final
Environmental Impact Statement, Lyman-Tarrington 115-KV
Transmission Line and Torrington Substation—Pick-Sloan
Missouri Basin Program" (July 31, 1972).
Department of the Interior, Bureau of Reclamation, "Final
Environmental Impact Statement, Mountain Park Project,
Oklahoma" (March 27, 1972).
Department of the Interior, Bureau of Reclamation, "Final
Environmental Impact Statement, Yolo County Flood Control
and Water Conservation District, Application Under the
Small Reclamation Projects Act" (July, 1971).
Department of the Interior, Bureau of Reclamation, Regional
Office, Region 7, Denver, Colorado, "Draft Environmental
Impact Statement, Long Draw Reservoir Enlargement Project,
Colorado, an Application Under the Snail Reclamation Projects
Act for Water Supply and Storage Company" (June 7, 1972).
Department of the Interior, Bureau of Reclamation, Region 1,
"Final Environmental Impact Statement, Lower Teton Division-
First Phase, Teton Basin Project, Idaho" (June 24, 1971).
Department of the Interior, Bureau of Reclamation, Regional
Office, Region 5, Amarillo, Texas, "Draft Environmental
Impact Statement, Pojoaque Unit, San Juan-Chama Project,
Colorado - New Mexico" (June 14, 1972).
DEPARTMENT OF THE ARMY
ARMY CORPS OF ENGINEERS
U.S. Army Engineer District, Kansas City, Missouri, "Draft Environ-
mental Impact Statement, Harry S. Truman Dam and Reservoir, Osage
River, Missouri" (September, 1972).
Hylton, A.R., et al., "Draft Environmental Impact Statement, Harry
S. Truman Dam and Reservoir, Osage River, Missouri," Appendix C,
prepared by Midwest Research Institute for the Department of the
Army, Kansas City District, Corps of Engineers (August 4, 1972).
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"Draft Environmental Impact Statement, Harry S. Truman Dam and
Reservoir, Osage River, Missouri," Appendix D, Comments of the
Environmental Defense Fund and the Missouri Chapter of the Wildlife
Society for Use in Preparation of the Draft Environmental Impact
Statement {July 31, 1972).
U.S. Army Engineer District, St. Louis, Missouri, "Draft Environmental
Impact Statement, Meramec Park Lake, Meramec River, Missouri" (April,
1973).
U.S. Army Engineer District, St. Louis, Missouri, "Draft Environmental
Impact Statement, Meramec Park Lake, Meramec River, Missouri,"
Appendices A-J (April, 1973).
U.S. Army Engineer District, Galveston, Texas, "Final Environmental
Impact Statement, Wallisville Lake, Trinity River, Texas" (December 13,
1971).
U.S. Army Corps of Engineers, Tulsa District, "Draft Environmental
Impact Statement, Shidler Lake, Salt Creek, Oklahoma" (January 27,
1971).
U.S. Army Engineer District, Baltimore, Maryland, "Final Environmental
Impact Statement, Cowanesque Lake, Cowanesque River, Tioga County,
Pennsylvania" (October 31, 1972).
U.S. Army Corps of Engineers, Tulsa District, "Final Environmental
Impact Statement, DeQueen Lake, Rolling Fork River, Arkansas"
(January 7, 1972).
U.S. Army Corps of Engineers, Tulsa District, "Final Environmental
Impact Statement, Copan Lake, Little Caney River, Oklahoma"
(March 31, 1972).
U.S. Army Engineer District, Kansas City, Missouri, "Final Environ-
mental Impact Statement, Smithville Lake, Little Platte River,
Missouri" (March, 1972).
U.S. Army Corps of Engineers, Nashville District, Ohio River
Division, "Draft Environmental Impact Statement, Temporary Naviga-
tion Lock (Modification of Lock and Dam 53), Ohio River, Illinois
and Kentucky" (December, 1972).
U.S. Army Engineer District, Walla Walla, Washington, "Draft Envi-
ronmental' Impact Statement, Catherine Creek Dam and Lake, Catherine
Creek, Oregon" (July, 1972).
U.S. Army Engineer District, Louisville, Kentucky, "Draft Environ-
mental Impact Statement, Highland Lake, Fall Creek Basin, Indiana"
(May, 1972).
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U.S. Army Engineer District, Sacramento, California, "Draft Environ-
mental Impact Statement, Lakeport Lake Project, Scotts Creek, California
(August, 1972).
U.S. Army Engineer District, Louisville, Kentucky, "Final Environments!
Impact Statement, Taylorsville Lake, Salt River, Kentucky" (July 16, 1971}
U.*S. Army Engineer District, Huntington, West Virginia, "Final Envi-
ronmental Impact Statement, Salt Creek Lake, Salt Creek, Scioto
River Basin, Ohio" (April 30, 1971).
U.S. Army Engineer District, Albuquerque, New Mexico, "Final Envi-
ronmental Impact Statement, Los Esteros Lake, Santa Rosa, New Mexico
(August 6, 1971).
U.S. Army Engineer District, Portland, Oregon, "Final Environmental
Impact Statement, Lost Creek Lake Project, Rogue River, Oregon"
(May 8, 1972).
U.S. Army Engineer District, Charleston, South Carolina, "Draft
Environmental Impact Statement, Clinchfield Dam and Reservoir,
Broad River Basin, North Carolina and South Carolina" (May, 1972).
Department of the Army, "Draft Environmental Impact Statement, Curry
Creek Reservoir, North Oconee River, Georgia" (May, 1972).
U.S. Army Engineer District, Huntington, West Virginia, "Draft Envi-
ronmental Impact Statement, Whiteoak Dam and Reservoir, Whiteoak
Creek Basin, Ohio" (May, 1972).
U.S. Army Corps of Engineers District, Seattle, Washington, "Final
Environmental Impact Statement, Mud Mountain Dam and Reservoir,
White River, Washington" (January, 1972).
U.S. Army Engineer District, New York, New York, "Final Environmental
Impact Statement, Atlantic Coast of Long Island, Fire Island Inlet and
Shore Westerly to Jones Inlet, New York, Beach Erosion Control and
Navigation Project" (February, 1971).
Department of the Army, "Draft Environmental Impact Statement, El
Doredo Lake, Kansas Project" (April, 1971).
TENNESSEE VALLEY AUTHORITY
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Shelby 500-KV
Substation and Transmission Line Connections" (September 22,
1971).
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Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Gas Turbine Peaking
Plant Addition, Thomas H. Allen Steam Plant-Memphis, Tennessee"
(October 29, 1971).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Gas Turbine Peaking
Plant Addition, Units 1-8, Colbert Steam Plant-Colbert County,
Alabama" (March 31, 1972).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Gas Turbine Peaking
Plant Addition, Units 17-20, Thomas H. Allen Steam Plant, Shelby
County, Tennessee" .(March 31, 1972).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Proposed New
Lock-Pickwick Landing Dam" (September 13, 1972).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Rehabilitation
of the Nolichucky Project" (March 10, 1972).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Tellico Project",
Volume 1 (February 10, 1972).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Tellico Project",
Volume 2 (February 10, 1972).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Tellico Project",
Volume 3 (February 10, 1972).
Tennessee Valley Authority, Office of Health and Environmental
.Science, "Final Environmental Impact Statement, Control of
Eurasian Watermilfoil (Kyriop'ri-jllim sp-icatwn L.) in TVA
Reservoirs" (September 29, 1972).
Tennessee Valley Authority, "Final Environmental Impact State-
ment, Experimental S02 Removal System and Waste Disposal Pond
Widows Creek Steam Plant" (January 15, 1973).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Yellow Creek
Port Project" (November 30, 1971).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Bear Creek Project"
(December 29, 1972).
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Tennessee Valley Authority, "Final Environmental Impact Statement,
Briceville Flood Relief Project" (May 29, 1973).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Duck River
Project" (April 28, 1972).
Tennessee Valley Authority, Office of Health and Environmental
Science, "Final Environmental Impact Statement, Policies
Relating to Sources of Coal Used by Tennessee Valley Authority
For Electric Power Generation" (December 6, 1971).
UNITED STATES DEPARTMENT OF AGRICULTURE
SOIL CONSERVATION SERVICE
United States Department of Agriculture, Forest Service, Eastern
Region, "Final Environmental Impact Statement, Council Bluff
Reservoir, Potosi Ranger District, Clark National Forest, Iron
County, Missouri" (August 17, 1971).
United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Patterson
Watershed Project, Stanislaus County, California" (January,
1973).
United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Upper Salt
Creek Watershed, Cook, Lake, and DuPage Counties, Illinois"
(May, 1973).
United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Nescopeck
Creek Watershed Project, Luzerne County, Pennsylvania"
(May, 1973).
United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Moorehead
Bayou Watershed, Sunflower County, Mississippi" (May, 1973).
United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Palatlakaha
River Watershed, Lake County, Florida" (April, 1973).
United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Banlick Creek
Watershed, Boone and Kenton Counties, Kentucky" (March, 1973).
United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Little Creek
Watershed Project, Laurens and Wheeler Counties, Georgia"
(March, 1973).
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United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Nutwood Water-
shed, Illinois" (March, 1973).
United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Prickett
Creek Watershed, West Virginia" (February, 1973).
United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Stevens-Rugg
Watershed Project, Franklin County, Vermont" (January, 1973).
United States Department of Agriculture, Soil Conservation
Service, "Final Environmental Impact Statement, Lost Creek
Watershed, Newton County, Missouri" (January, 1973).
United States Department of Agriculture, Soil Conservation,
"Final Environmental Impact Statement, Georgetown Creek
Watershed Project, Bear Lake County, Idaho" (February, 1973).
FEDERAL POWER COMMISSION
Federal Power Commission, Bureau of Power, "Staff Draft
Environmental Impact Statement, Chippewa Reservoir Project
No. 108-Wisconsin" (April, 1973). [Applicant—Northern
States Power Co., Eau Claire, Wisconsin]
Federal Power Commission, Bureau of Power, "Final Environ-
mental Impact Statement, Request to Grant an Easement Affecting
Certain Lands Saluda Project, No. 516-South Carolina" (April,
1973). [Applicant—South Carolina Electric & Gas Company,
Columbia, South Carolina]
Federal Power Commission, Bureau of Power, "Final Environmental
Impact. Statement, Modified Blue Ridge Project No. 2317-North
Carolina/Virginia" (June, 1973). [Applicant—Appalachian
Power Company, New York, New York]
OU.S. GOVERNMENT PRINTING OFFICE:1974 582-414/105 1-3
221
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
W
An Assessment Methodology for the Environmental Impact
of Water Resource Projects
M. L. Warner, J. L. Moore, S. Chatterjee,
D. C. Cooper, C. Ifeadi, W. T. Lawhon, and R. S. Reimers
Battelle Columbus Laboratories
Columbus, Ohio
u.
Environmental Protection Agency
5 Report Date
6
68-01-1871
Pcaiod f nt-ewd
Final Report
Environmental Protection Agency report number, EPA-600/5-7l*-Ol6, July 197k
This report presents materials intended for use by reviewers of environmental impact
statements on major water resources development reservoir projects. The report is
prepared as a series of six related but individually referenced discussions of the
following major topics:
. Reservoir project planning, construction, and operation activities;
. Water quality impacts of reservoir construction;
. Ecological impacts of reservoir construction;
. Economic, social, and aesthetic impacts of reservoir construction;
. Review criteria for assessing general statement completeness and accuracy;
. A review of impact assessment methodologies.
The materials presented attempt to call to the reviewer's attention important issues
or potential impacts that an adequate impact statement should address. In addition, the
water quality and ecological impacts sections discuss the site-specific conditions under
which a given potential impact may or may not occur.
The section on water quality impacts also presents a detailed comparison of mathemati-
cal models for predicting impacts on water temperature, dissolved oxygen levels, and
some chemical constituents of surface waters. The sections dealing with water quality,
ecological, and economic-social-aesthetic impacts include extensive citations to
relevant literature the impact statement reviewer may wish to consult for further
information.
17a. Descriptors
Environmental Impact Statements, Ecological Impacts Water Quality
Assessment Methodologies, Reservoirs
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D.C. 2024O
H. V. Kibbv
U.S. Environmental Protection Agency
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