GUIDELINES FOR REVIEW OP
ENVIRONMENTAL IMPACT STATEMENTS
VOLUME III
IMPOUNDMENT PROJECTS
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF FEDERAL ACTIVITIES
-------
PREFACE
This volume presents detailed guidance for the
assessment of the primary impacts of impoundment projects.
In its current form, this volume is intended to serve
as a supplement to the Environmental Protection Agency's 309
Review Manual and existing assessment techniques related
to water resources projects. In toto, these documents
provide the detailed framework for the Environmental
Protection Agency's review of impoundment project environ-
mental impact statements.
As additional or refined review techniques and
assessment procedures become available, this document will
be reissued or revised as necessary. Note, however, that
only the numbered copies are on the distribution list
for revised materials.
Comments and suggestions regarding this document
should be directed to the attention of the Director,
Office of Federal Activities (A-104), Environmental
Protection Agency, Washington, D.C. 2046 0.
ii
-------
Contents
Page
Preface ii
Contents iii
List of Illustrations vi
I. Introduction 1-1
II. Impoundment Project Review (Note on
Cooling Lakes) II-l
II.A. Pre-EIS Activity II-2
II.B. Review of Draft EIS II-4
II.B.l Project Description II-5
II.B.2 Relationship of Project
to Land Use Plans,
Policies, and Controls for
the Affected Area II-5
II.B. 3 Probable Impact of the
Proposed Project 11-10
II.B.4 Alternatives to Proposed
Action 11-15
II.B. 5 Probable Adverse Impacts that
Cannot be Avoided 11-16
II.B.6 Relationship of Short-Term
Uses vs. Long-Term
Productivity 11-17
II.B.7 Irreversible and Irretrievable
Commitments to the Proposed
Project 11-17
II.B.8 Other Interests and
Considerations of Federal
Policy 11-18
II.C. Pre-Final Impact Statement Consulta-
tion 11-19 *
II.D. Review of Final EIS 11-20
II.E. Project Follow-Up 11-21
III. Project Rating III-l
IV. Identification and Assessment of Project
Impacts IV-1
IV.A. Review of Land Use Impacts IV-1
IV.A.1 Sources of Impacts IV-1
A.l.a. In Impoundment IV-1
A.l.b. In Vicinity of Im-
poundment IV-2
A. I.e. In Impoundment Area
of Influence IV-3
IV.A.2 Review of Impact Quantifi-
cation IV-3
IV.A.3 Assessments of Impacts IV-10
iii
-------
CONTENTS (Cont'd)
Page
IV.B. Review of Water Quality and Ecological
Impacts IV-13
IV.B.1. Sources of Impacts IV-13
IV.B.l.a. Impoundment Construc-
tion IV-13
IV.B.l.b. Inundation of Land
and Creation of
Artificial Lakes . . . IV-16
IV.B.I.e. Downstream Impacts
from Impoundment
Operation IV-21
IV.B.2. Review of Impact Quantification . IV-24
IV.B.2.a. Impoundment Construc-
tion Impacts IV-25
IV.B.2.b. Impacts of Land In-
undation and Creation
of Artificial Lakes . . IV-26
IV.B.2.c. Downstream Impacts
from Impoundment
Operation IV-37
IV.B.3. Assessment of Impacts IV-46
IV.B.3.a. Impacts During Con-
struction IV-47
IV.B.3.b. Impacts Due to Creation
of an Artificial Lake
and Impoundment
Operation IV-51
IV.C. Review of Solid Waste Management Impacts . IV-66
IV.C.l. Sources of Impacts . IV-66
IV.C.2. Review of Impact Quantification . IV-69
IV.C.3. Assessment of Impacts IV-70
IV.D. Review of Air Impacts IV-73
IV.D.l. Sources of Impacts IV-73
IV.D.2. Review of Impact Quantification . IV-74
IV.D.3. Assessment of Impacts IV-75
IV.E. Review of Noise Impacts IV-78
IV.E.l. Sources of Impacts IV-78
IV.E.2. Review of Impact Quantification . IV-78
IV.E.3. Assessment of Impacts IV-83
XV
-------
CONTENTS (Cont'd)
Page
Appendix: Federal Agency Procedures Related to
Environmental Assessment of Impoundment
Projects
U.S. Army Corps of Engineers A-2
Soil Conservation Service A-5
Bureau of Reclamation A-7
Tennessee Valley Authority A-9
Federal Power Commission A-ll
Water Resources Council and River Basin
Commissions A-12
Fish and Wildlife Service A-14
References R-l
v
-------
LIST OF ILLUSTRATIONS
Table Page
II-l Impoundment Review Checklist 11-21
II-2 Impoundment Impact Checklist 11-28
III-l Standards, Criteria, and Regulations Related
to Impoundment Projects III-3
III-2 Rating Impoundment Projects III-4
IV-1 Soil Losses from 5 Inches of Simulated Rain on
Denuded Slopes for Various Types and Rates of
Mulch IV-5 0
IV-2 Water Quality Criteria for Selected Constituents
and Probable Effect of Impoundment IV-53
IV-3 Maximum Weekly Average Temperature for Spawning
and Short-Term Maxima for Survival During the
Spawning Season (Centrigrade and Fahrenheit) . . IV-54
IV-4 Types of Impoundments Equipped with Selective
Withdrawal IV-57
IV-5 Waste Generation Rates for Recreation Sites . . IV-70
IV-6 Summary of Solid Waste Impacts IV-72
IV-7 National Primary and Secondary Air Quality
Standards IV-76
IV-8 Typical Ranges of Noise Levels at Construction
Sites with a 50 dBA Ambient Typical of Suburban
Residential Areas IV-80
IV-9 Typical Ranges of Noise Levels at Construction
Sites with a 70 dBA Ambient Typical of Urban
Areas IV-80
IV-10 Reduction of A-Scale Sound Level at Various
Distances from a Vehicular Point Source, Relative
to 50-ft. Distance IV-81
IV-11 Yearly Average Equivalent Sound Levels Identified
as Requisite to Protect the Public Health and
Welfare with an Adequate Margin of Safety . . . IV-85
Figure
1-1 Impoundement Project Review Elements 1-3
IV-1 Crooked Creek Project Area-Volume Curve .... IV-31
IV-2 Tellico Project Area-Volume Curve IV-31
IV-3 Le for Intermittent Ljyjj^ to L^ IV-82
vi
-------
I. INTRODUCTION
The development of water resources continues at a high
level in response to the need for water supply, flood control,
irrigation, power generation, navigation, and other purposes.
Virtually all of the larger streams in the United States are
either already impounded or have been studied and identified
as potential impoundment sites. Concurrently, pressures for
conservation and preservation have been increasing because of
concerns for the ecological, historical, aesthetic, and recrea-
tional values of our natural resources. There is also a growing
awareness that these resources are rapidly being lost to develop-
ment of all kinds. The conflict between development and preserva-
tion is particularly evident in the case of impoundment projects,
since the major commitments of a freely flowing stream and
riparian lands to permanent or periodic inundation, and the
associated water quality and ecological impacts, are essentially
unavoidable as long as the project remains in place.* From an
ecological standpoint the worst thing that can happen to a
stream is impoundment, and the second worst thing is channeliza-
tion.^- Impoundment has totally changed the molluscan fauna of
the Tennessee River, dammed to form the Kentucky Reservoir, and
it is concluded that the rich preimpoundment fauna is doomed.
Over one-half the known species of mussels of the Illinois
River have disappeared, and many others are on the verge of ex-
tinction. In addition, the maintenance of impoundments can
result in significant environmental impacts in areas totally
removed from the impounded area. For example, to prolong the
life of reservoirs and to maintain the depth of navigation
channels about 4 50 million cubic yards of bottom materials are
dredged each year, and much of the spoil is dumped on marshes,
swamps, and flood plains. It is apparent, then, that a complete
assessment of resource commitments in terms of land, natural
stream, and alteration of riverine ecology is fundamental to
the process of weighing the benefits of an impoundment against
the project's impacts.
Often the basic question of whether a given stream should
be impounded at all sparks the most controversy and cannot be
adequately answered using traditional methods of analyzing bene-
fits and costs. Intangible costs, relating to the maintenance
of natural environmental values, take on greater significance as
the supply of the affected resources declines. Monetary values
*The term, "Impoundment projects" in this document includes
most fresh water impoundments from the largest to the small
watershed work type.
1-1
-------
for land acquisition, recreation days lost, and other
factors do not adequately reflect these costs. The weighing of
impacts that involve long-term resource commitments needs to
be examined very carefully in the context of environmental goals
and objectives. Planning must also be conducted relative to
the fate of the project after its useful economic or structural
life ends. The dismantling, evaculation, or continued
maintenance of an impoundment should be consistent with
environmental safeguards used during facility operation.
The seriousness of this problem is illustrated by the fact
that reservoirs in the Great Plains and elsewhere are
accumulating sediments at the rate of 1 million acre feet
per year. The average life of such reservoirs is estimated
to be less than 50 years.
EPA's involvement in the impoundment development
process stems from the mandates of the Federal Water
Pollution Control Act (FWPCA), as amended, the National
Environmental Policy Act (NEPA) of 1969 and the Clean Air
Act Amendments of 1970.*
Under the FWPCA, EPA has authority and responsibility
for effecting national water quality goals specified by the
law. In particular, impoundment projects may affect EPA
authority under Sections 102(b), 208, 303, 313, 402, and
404 of the FWPCA. The relationship of impoundments to these
sections of the FWPCA are addressed in more detail below.
In view of the legal jurisdiction of, and special
expertise within EPA, Section 102(2)(C) of the NEPA
obligates Federal agencies to obtain comments from EPA
wherever an action related to air or water quality, noise
abatement, solid waste management, generally applicable
environmental radiation criteria and standards, or other
provisions of the authority of EPA are involved. Section 309
of the Clean Air Act Amendments of 1970 gives EPA the
explicit legal mandate to comment in writing on the environ-
mental impact of any matter relating to EPA's duties and
responsibilities. To implement these responsibilities,
the EPA manual Review of Federal Actions Affecting the
Environment2 (hereafter referred to as the "309 Review
Manual" has established detailed policies, responsibilities,
and administrative procedures for the Agency's review of
Federal actions impacting the environment. This manual
provides that, where an environmental impact statement
(EIS) has been sent to EPA for comment, EPA's comments on
*A listing of other relevant legislation, Executive Orders,
and Office of Management and Budget circulars and bulletins
may be found in Basic Documents Concerning Federal Programs
to Control Environmental Pollution From Federal Government
Activities, U.S. EPA, Office of Federal Activities.
February 19 75.
1-2
-------
the EIS shall also constitute its comments for purposes
of the Section 309 review. Furthermore, it is EPA policy to
use the Section 309 process in conjunction with EPA's other
authorities to: (a) provide technical assistance to Federal,
State, regional, and local governmental entities; (b) assist
the environmentally-related activities of EPA and other
Federal, State, regional, and local entities; and
(c) assist Federal agencies in meeting the objectives of
the National Environmental Policy Act.
Because the 309 Review Manual does not provide guidance
for applying the Section 309 review process to specific types
of projects, the Office of Federal Activities, in conjunction
with the EPA program and regional offices, has prepared a
series of detailed review guidelines for several major
project categories. As one of the documents in that series,
this guideline provides detailed information for applying
the EPA EIS review process to impoundment projects.
Figure 1-1 illustrates the EIS review process. Chapters II and
III of this guideline expand the manual's guidance for
implementing the EPA policy described above. Chapter IV
supplements the manual by providing a synthesis of the
possible land use, water quality, ecological, solid waste,
air, and noise impacts associated with impoundment projects.
Information on the analysis and assessment of such impacts
is also presented. Finally, a detailed bibliography is
provided to permit the reviewer to explore specific problem
areas in greater depth.
Figure 1-1: Impoundment Project Review Elements
REVIEW GUIDELINE- VOLUME III
1-3
-------
II. IMPOUNDMENT PROJECT REVIEW
As described in the 309 Review Manual, the EPA EIS
review process consists of pre-EIS activities, review
of Draft EIS's, pre-final EIS Liaison, review of Final
EIS's, and post EIS follow-up. Guidance for the review
of impoundment projects is given in the following sub-
sections in terms of these five review phases. While it is
recognized that unique situations within each region may
dictate emphasis on one phase over another, all phases of
the review process should be conducted to the fullest extent
of the region's resources. In any case, it should be kept
in mind that the goal of the review process is to maximize
the effectiveness of the EPA involvement in impoundment
projects. Generally, this is accomplished when the EPA
involvement: (1) reflects the total environmental responsi-
bilities of EPA, especially in those cases where the basic
nature of the EIS indicates a need for a coordinated
multi-program response; (2) is part of a continued working
relationship with the originating agency to improve their
project planning and design processes; (3) focuses sharply
on environmentally unsatisfactory actions; (4) lends EPA
support to projects having beneficial impacts on the
environment; and (5) produces review responses which are
expressed in constructive language, pointing out specific
environmental problems that a proposed action might cause.
Note on Cooling Lakes
Impoundments constructed for the purpose of serving
as cooling lakes for stream electric power plants will be
treated in a separate technical manual yet to be developed.
Revisions to the effluent guidelines for the Steam Electric
Power Generating Point Source Category were proposed on
26 March 1976 (41 Federal Register 12694) to allow for the
construction and use of on-stream cooling lakes, if the lakes
meet criteria involving (1) the environmental acceptability
of the lake in terms of municipal water supplies, shellfish beds
and fishery areas, wildlife and recreation; (2) thermal
efficiency; (3) recirculation requirements. Since procedures
and information on review of cooling lakes proposals will be
the subject of a separate manual, they are not discussed herein.
II-l
-------
II.A. Pre-EIS Activity
"Pre-EIS activity" is a generic term which includes
pre-EIS coordination within EPA as well as coordination and
information exchanges with Federal, State, and local agencies
responsible for project planning or licensing. Pre-EIS
activity within EPA involves the coordination of EIS
review with other EPA actions which may affect the impoundment
project, such as discharge permits (NPDES), review of 404
permits, non-point source management under Sections 208 and
303, Federal facilities pollution control under Section 313,
flow augmentation determinations under Section 102(b)(3), and
sole-source aquifer determinations under Section 1424(e) of
the Safe Drinking Water Act of 1974. Additionally, EPA positions
expressed previously on the project or project site, as might be
contained in reviews of earlier EIS's, Congressional correspondence,
or other agency statements, must be considered in developing a
consistent EPA position.
External pre-EIS activity includes a wide-range of
activities outlined in the 309 Review Manual: (1) review of an
applicant's environmental report or agency pre-draft EIS;
(2) review of negative declarations; (3) participation at agency
meetings describing the project? (4) substantive discussions
with agency officials responsible for a proposed action, with
emphasis on alternative mitigation measures; (5) provision of
background materials for use in developing the EIS; (6) review
of basin plans (Level B studies); (7) site visits. In order
to fully realize such opportunities for pre-EIS liaison it
is important that EIS Coordinators maintain frequent and regular
contact with appropriate field agencies. EIS Coordinators
should understand planning processes and associated outputs
that might be useful in determining an early environmental
assessment of developing projects. As a reference, the
Appendix contains brief descriptions of the planning processes
of the Corps of Engineers, the Soil Conservation Service, the
Water Resources Council, the River Basin Commissions, and
the Fish and Wildlife Service.
Pre-EIS liaison with Federal agencies may also be
formalized through (1) a memorandum of understanding or
(2) through protocols developed by the Federal agency. A
memorandum of understanding, such as that developed with the
Nuclear Regulatory Commission (NRC) contains provisions for
joint preparation of an EIS for projects requiring an NRC
license and a new source NPDES permit from EPA. (The NRC-EPA
memorandum of understanding is contained in the Appendix).
Under such an MOU, EPA bears responsibilities both as an EIS
II-2
-------
preparer (as issuer of the new source permit) and EIS
reviewer (of the EIS on NRC's licensing action). In order
to ensure an even-handed and consistent EPA approach in
discharging these duties, the MOU establishes procedures
requiring close coordination between the agencies at the
EIS preparation stage. This specialized form of pre-EIS
liaison is necessary in those circumstances in which EPA
is involved in granting a permit to a facility that is
being licensed by another Federal agency. MOU's analogous
to that between EPA and NRC will probably be developed
with the Rural Electrification Administration and the Federal
Power Commission.
A more general type of arrangement is the pre-EIS
protocol established by the Soil Conservation Service. In
the early stages of planning, the SCS writes to EPA's
regional offices to seek consultation on matters within EPA's
area of responsibility and special expertise (See section
650.10(a)(6) of the SCS NEPA regulations). It is the
responsibility of the EIS coordinator to ensure that the
region is responsive to the SCS request for technical
assistance as the planning process is initiated.
Pre-EIS activity is extremely important in preventing
potential environmental problems from being realized. It
is at the very early pre-EIS stages of project development
that environmental problems are most susceptible to EPA-
recommended mitigation measures. Similarly, the consideration
of project alternatives is most practical when done before
any single alternative becomes entrenched in the minds of
project planners. The EIS review function is one of the few
Agency programs by which EPA practices prevention, rather
than abatement, of environmental problems. To secure the
greatest benefit from this program, effective pre-EIS
liaison is essential.
II-3
-------
II.B. Review of Draft EIS
While the purpose of the review is to assess the
environmental impact of the proposed project, it is also
obviously necessary to assess the completeness (i.e.,
adequacy) of the material presented in the EIS. It is
emphasized that the main objective of the EPA review is to
assess the impacts related to air, water, noise, solid
waste management, and other environmental areas within
EPA's jurisdiction and expertise, and not primarily to
critique the way in which the EIS is organized or written.
In determining the adequacy of the EIS, the reviewers
should consider both the material presented in the EIS and
the material presented in reference documents. According to
the Council on Environmental Quality (CEQ) guidelines for
preparation of impact statements,-3 "Highly technical and
specialized analyses and data should be avoided in the body
of the draft impact statement. Such materials should be
attached as appendices or footnoted with adequate bibliographic
references." In what follows, then, the term "EIS" is used
in the generic sense of "EIS and referenced technical documents,"
provided that, first, the EIS contains adequate summaries of
the methodologies and results of the various technical
analyses, and, second, the detailed reports describing t^.ese
methodologies and results are available.
The reviewer should note that the foregoing does not
preclude the requirement that the EIS itself should contain
sufficient "information, summary technical data, and maps and
diagrams, where relevant, adequate to permit an assessment
of potential environmental impact by commenting agencies and
the public."
A systematic review procedure is necessary to insure
that all significant primary impacts have been considered
and that the assessment of the various types of impacts
can be combined into a single assessment of the project.
The CEQ Guidelines (1500.8) have defined the major analysis
categories to be included in an EIS:
(1) Project description;
(2) Relationship to land use plans, policies,
and controls for the affected area;
(3) Probable impact of the project;
(4) Alternatives to the project;
II-4
-------
(5) Probable adverse impacts which cannot be avoided;
(6) Relationship between local short-term use of
man's environment and the maintenance and
enhancement of long-term productivity;
(7) Irreversible or irretrievable commitments of
resources;
(8) Other interests and consideration of Federal
policy affecting the project decision.
The following review guidance is structured along these
1ines .
II.B.l. Project Description
Project description includes a statement of project
purposes as well as a description of environmental effects.
According to the CEQ guidelines, "the amount of detail
provided (in the description of the proposed action) should
be commensurate with the extent and expected impact of the
action, and with the amount of information required at the
particular level of decision making...." The reviewer should
place the project in context with respect to the purpose of
the project, the area in which the project will be constructed,
and the relationship between the proposed project and other
projects. This effort should aid the reviewer in defining the
general level of review that will be required. To gain insight
into a project, the reviewer may need to develop information
from outside sources. Investigation of the history of project
development and discussions with local groups who may have
personal knowledge of the project characteristics can provide
useful additional information and understanding of the project.
As an aid in checking the completeness of the EIS, a
review checklist for impoundment projects is given in
Table II-l. Since no single checklist can be applied to all
situations, the reviewer is cautioned to utilize the
technical review information in Chapter IV to determine which,
and to what extent, each of the checklist items apply to the
specific project under review.
II.B.2. Relationships of Project to Land Use Plans, Policies
and Controls for the Affected Area
EPA's particular interest in reviewing an impoundment
project under this criteria centers on the consistency of the
project with the requirements of the Federal Water Pollution
II-5
-------
Control Act, in particular sections 208 and 303. Under
guidelines recently issued as 40 CFR Parts 130 and 131,
States are to assume overall responsibility for development
and implementation of water quality management plans
mandated by section 208 and 303 to meet the goals of the
FWPCA: (1) the determination of effluent limitations needed
to meet applicable water quality standards, including the
requirement to at least meet existing water quality; and
(2) development of State and areawide management programs
to implement abatement measures for all pollutant sources.
All States have developed a river basin planning process
consistent with Section 303(e) of the Act. The basin
planning program has resulted in the development of plans
setting out effluent limitations needed by point sources to
meet existing State water quality standards (Phase I vtfater
Quality Management Plans). Under 40 CFR Parts 130 and 131,
States must consider revisions to water quality standards to
meet the "fishable, swimmable" goals of Section 101(a) (2)
of the Act. The revised plans (Phase II Water Quality
Management Plans) should consider all available means to
meet water quality standards including effluent limitations
for point sources and management of non-point sources.
Impoundment projects play a double role in the overall
water quality management plan. On the one hand, impoundments
are hydrologic modifications classified as possible indirect
sources of pollution requiring the application of "best
management practices."* On the other hand, an impoundment
may provide storage leading to water quality improvements
by retaining and settling polluted flood waters until their
eventual release during periods of low flow. Section 102(b)
of PL 92-500 makes specific provision for the consideration
of water quality storage in impoundments constructed by
Federal agencies or licensed by the Federal Power Commission.
In addition, Section 102(b) (3) gives EPA the responsibility
for determining the need for, value of, and impact of the
inclusion of such storage for water quality control. Section
102(b)(1), however, specifically prohibits use of streamflow
regulation as a substitute for adequate treatment or
source management.
*The term Best Management Practices (BMP) means a practice, or
combination of practices, that is determined by a State (or
designated areawide planning agency) after problem assessment,
examination of alternative practices, and appropriate public
participation to be the most effective, practicable (including
technological, economic, and institutional considerations) means
of preventing or reducing the amount of pollution generated by
nonpoint sources to a level compatible with water quality goals.
II-6
-------
The development of State water quality management plans
must factor in the water quality effects of existing
impoundments, both as indirect sources of pollution and as
possible means of retaining indirect source pollution from
extreme hydrologic events, or of reducing through flow
augmentation the adverse effects of point source pollution.
Determinations by EPA under 102(b) (3) should be tied to the
water quality management plan for the river basin area that
will be affected by proposed federally-sponsored or licensed
impoundments. Section 102(b)(3) is discussed in more detail
below.
Present and Projected Waste Discharges Within Reservoir
Area. The water quality management (WQM) plan will contain
information on the location and characteristics of wastewater
discharges. If a proposed impoundment is to be used for
public water supply, water contact recreation, or other
purposes which require water of uniformly high quality,
more stringent effluents limitations or even relocation of
wastewater outfalls may be necessary. Nutrients, potentially
toxic chemicals, organic matter, or other substances contained
in treated wastewater discharges may be readily trapped and
perhaps reach undesirable concentrations in the impounded
water body, reducing its value for intended uses.
Alteration of Hydrographic Regime. A WQM plan is
to contain, for each water quality segment, an analysis of the
total maximum daily loads of those pollutants that violate
applicable water quality standards, including a provision for
seasonal variation. The plan should establish discharge load
allocations or effluent limitations among significant discharges
with an allowance for anticipated economic and demographic
growth over twenty years. These determinations will
generally be made through application of mathematical modeling
techniques for specific flow conditions.
Many impoundments will be located on streams where water
pollution is not a problem. Their operation may cause major
changes in the flow regime at downstream points where serious
water quality problems do exist. Low flows may be augmented,
even if no storage has been allocated specifically for
water quality control, and high flows during normally wet
seasons may be severely curtailed as water is held for later
release. Such changes may affect previously determined
waste load allocations for downstream water quality segments
or priorities for treatment plant construction.
II-7
-------
4
EPA regulations require that WQM plans be revised
every five years, or more frequently where significant
changes occur within the basin as brought about, perhaps, by
impoundment construction. The affected State should be consulted
regarding the possible impacts of regulated flow patterns on its
areawide water quality management program. As a matter of
policy concerning flow regulation by an impoundment project,
EPA considers any flow regulation practices that result in
lower than natural low flows to be in violation of the antidegrada-
tion clause of the water quality standards. On the other hand,
any dependable upward revision of low flows which is expected
from the operation of a proposed reservoir may affect interpre-
tation of water quality standards and planning for individual
treatment works. Both water quality standards and design of
treatment plants are based on a specific, often statistically
derived low flow value that may not be representative of the
Post-impoundment flow conditions. Ideally, these issues
should be resolved by the state water pollution control agency,
with the assistance of EPA, during the planning phase of the
impoundment.
Alteration of Preimpoundment Water Quality. An impound-
ment may have both beneficial and adverse effects on water
quality in the impoundment and in downstream reaches.
Changes in water quality parameters may directly affect
the attainment of water quality standards and associated uses.
For example, anaerobic conditions existing in the impoundment
hypolimnion may result in high manganese and iron content,
thus resulting in increased costs of treatment for water
supply facilities. A more direct effect of the impoundment
would be the elimination of a stream cold-water fishery,
a high use supportable in a free-flowing stream but not
in an impoundment. Improvement of water quality may be
directly related to increased streamflow and waste assimilative
capacity or to the settling and retention characteristics of
the reservoir pool. Because basin planning, area-wide waste
treatment management planning, and the discharge permit
program are strongly oriented to the analysis and regulation
of specific pollutants, predicted changes caused by impoundment
may need to be considered. For example, an impoundment may
substantially reduce suspended solids, turbidity, or coliform
bacteria. If any of these parameters violate water quality
standards or cause water quality problems in and downstream from
a proposed reservoir area, then there may be cause for revising
effluent limitations or other restrictions on these pollutants
to allow for the "treatment" capacity of the impoundment. Any
degradation of preimpoundment water quality, such as reduction
of dissolved oxygen in the discharge, is detrimental.
II-8
-------
Remedial measures should be evaluated during project
planning and EIS review just as would be done for any other
discharge which adversely affects water quality (see section
IV.B.3 for descriptions of several alternatives).
Alteration of Water and Related Land Use. The direct and
indirect changes in land use induced by a reservoir may have
far reaching effects on water quality. In some cases,
implications for future land use may be readily apparent.
For instance, the location and amount of land to be brought
into or taken out of agricultural production by use of
impoundment-supplied irrigation water should be fairly
well defined.
Likewise, storage allocated for municipal or industrial
water supply may aid in supporting future development within
or near those municipalities receiving the additional supply.
Other growth may occur in the vicinity of the reservoir itself
due to enhanced recreational attractiveness, or in downstream
flood plains if control storage is included.
Although development of particular areas would often
be expected regardless of whether an impoundment was
constructed, the project may nevertheless stimulate such
growth earlier than would otherwise have occurred. Coordina-
tion of impoundment planning (by BLM, COE, SCS, TVA, and
BuRec) and areawide water quality planning is necessary so
that potentially accelerated development, especially in
water limited regions, is properly evaluated. A revision of
growth projections in basin, land use, and other plans may
be required as allowances for wastewater volume increases
may no longer be representative of expected conditions.
The EPA, in overseeing state water quality management programs,
should ensure that any such changes in relevant planning
factors are properly considered and incorporated as necessary
into the basin plan.
Evaluation of Water Quality Control Storage. As discussed
earlier" Section 102 (b) of the Federal Water Pollution
Control Act (FWPCA), as amended, gives EPA full responsibility
for determining the need for, the value of, and the impact of
storage for water quality control at federally planned
impoundments and impoundments licensed by the Federal Power
Commission. EPA has issued a policy statement and guidelines
to regional offices for implementing the requirements of
Section 102(b). Pertinent EPA memoranda that are important
for review of impoundment EIS's and for pre-EIS studies of
water quality control storage are:
II-9
-------
° "Policy on Storage and Releases for Water Quality
Control in Reservoirs Planned by Federal Agencies,"
16 January 1973, (being revised).
0 "Implementation of Policy on Storage and Releases
for Water Quality Control in Reservoirs Planned by
Federal Agencies" (7 February 1973).
0 "Policy on Storage and Releases for Water Quality
Control in Reservoirs," amendment to the first
memorandum listed above (31 October 1973) .
The policies and guidance contained in these documents
apply to both requests for water quality storage studies and
to the review of reports and EIS's involving Federal proposals
for reservoir storage allocated for water quality purposes.
All the environmental consequences of such studies should
be considered so that the reviewer will be in a position to
comment on the water quality storage aspect of the draft
EIS when it is circulated. This procedure obviates the
need for an additional, detailed review of proposed storage
for water quality control at the draft EIS stage.
It should be noted that releases from multiple-purpose
projects for navigation, recreation, fish and wildlife
conservation, or other nonwithdrawal uses may provide incidental
water quality improvement benefits. EPA should evaluate flow
regulation specifically for these purposes in terms of its
effect on water quality. The impoundment planning agency is
responsible for actual determination of needs and values of
storage allocated to purposes other than water quality control.
II.B.3. Probable Impact of the Proposed Project
Review of the probable impact of the proposed project
should include the determination that all potentially signifi-
cant impacts have been identified, the potential impacts
have been properly quantified (within the limits of the
state-of-the-art and commensurate with the severity of the
impact expected), and that the impacts have been assessed
with respect to applicable standards, criteria, and
regulations.
In reviewing the EIS it is important to recognize the
complexity of the changes that can occur in water quality due
to impoundment and artificial management of a river. These
changes can be broadly classed as:
11-10
-------
0 Changes that might occur in the water due to the
presence of the project. This includes water
quality changes due to impoundment such as DO
depletion in bottom layers, seasonal temperature
stratifications, the effect on sediment transport,
warming trends, and potential eutrophication.
0 Changes which might occur in water quality due to
project operation. For instance, the operation
of a reservoir for flood control can prolong the
release of turbid water later in the year than
normal and can appreciably alter temperature regime
of the stream for a distance below the dam. The
elimination of high velocity flood flows can disrupt
the flushing action of the river and can lead to
increased sediment accumulation with resultant
effects on aquatic life. Levels of outlets will
be important in the regulation of water quality and
temperature of released waters. This may affect
downstream uses as well as downstream ecology.
Table II-2 presents a comprehensive list of environmental
impacts that could be associated with impoundment projects
and gives the location in Chapter IV for detailed discussions
of their identification, quantification, and assessment.
Since this is a general list, the reviewer must determine the
applicability of each item to the specific project at hand
through the use of Chapter IV and other sources. By proceed-
ing in this way, Table II-2 may be used as a checklist to help
insure a complete review. As a further aid in the use of
this table as an "overview," a synthesis of the major
considerations for physical impacts is given below.
In addition to the cumulative impacts of impoundment in
terms of the loss of land and a reach of freely-flowing
stream, important changes in impounded water may affect
water quality constituents in both the impounded stream
section and downstream reaches. Initial impacts from organic
decomposition resulting from permanent inundation of the
impoundment site will generally lead to adverse water quality
conditions, lasting from two to several years. The impounded
stream segment also experiences a permanent reduction in its
reaeration capacity, thus altering the capacity of the stream
to assimilate oxygen-demanding wastes; however, the long
retention times in other than run-of-the-river impoundments
may mitigate the loss of reaeration capacity. The modified
hydrological regime also results in important alterations in
aquatic biota, particularly under stratified conditions.
Oxygen depletion below the thermocline may prevent important
sport fish (e.g. trout, salmon) from inhabiting the lower
II-ll
-------
reaches of the impoundment (hypolimn ion). On the other hand,
the oxygen-rich waters above the thermocline (epilimnion) may
reach summer-time temperatures which are unsuitable for the
support of these cold-water game fish. Impoundments almost
invariably reduce the diversity of the aquatic ecosystem in
the impounded reach, leading to situations under which
rough fish will out-compete and predominate over more desirable
game fish.
The high probability that the quality of impounded water
will be poorer than that of streams flowing into the
impoundment has important implications for specific quality-
sensitive water uses for downstream reaches as well as the
impounded reach. Alterations of water quality that take
place in the reservoir will similarly be transferred to
downstream reaches. Sports fisheries downstream may be
affected by the generally poorer quality water released from
the impoundment. For municipal water supply, lowering of
water quality in the reservoir may necessitate increased
treatment costs for removal of iron, manganese, tastes and
odors, algae, or other undesirable substances. These
costs should be fully evaluated as a component of total
costs of the project.
Water quality changes in downstream reaches result from
the water quality of impoundment releases and by alteration
of natural flows, water temperatures, and waste assimilative
capacities. Stream conditions are not likely to remain
static over the life of an impoundment, however, and impacts
which may appear to be minor may become highly significant
when viewed in conjunction with other incremental effects.
An impoundment may alter the thermal regime through discharges
of treated wastewater and cooling water, increased urban
runoff from paved areas, and removal of streamside vegetation.
Although each of these effects may be small, when combined
they may jeopardize the maintenance of the natural stream
ecosystem. The same analysis may apply to changes in flow
regime, which arise not only from impoundments but also from
downstream withdrawal uses of river water, diversion, and
other losses.
Changes in water quantity and water quality downstream
from a dam are certain to affect river ecology. Elimination
or reduction of either cold or warm-water species of fish,
invertebrates, and other fauna can be anticipated at
impoundments that significantly change the thermal regime
of the river. Flow regulation, alone or along with temperature
and other changes, may interrupt fish migrations and spawning.
11-12
-------
Stabilization of flows may provide conditions more favorable
to some fish species, although the reduction of bank overflows
will detrimentally affect the seasonal wetland vegetation
characteristic of undeveloped river bottom lands and valley
storage areas. Traditionally, modification of fish and wildlife
resources, vegetation, and the ecology of areas affected
by impoundments has been equated with losses or gains of
hunting, fishing, or other recreational opportunities.
However, this sort of analysis ignores many of the intangible
values associated with the preservation of the remaining
rivers in their natural states. (For example, areas of
unique ecological or geological value would not be adequately
evaluated using this technique alone).
Many indirect ecological impacts are related to changes in
land use and increased development pressures resulting from
impoundment construction. Intensive recreational use of shore-
line areas around a reservoir will adversely affect wildlife
and wildlife habitat as will the relocation of roads, railroads,
and other facilities above the maximum reservoir elevation.
Residential or second home development along the shorefront and
on adjacent hillsides can also have detrimental impacts on terres-
trial ecology and aesthetics. In the longer term, increased
traffic and home development will exert additional pressures on
wildlife in areas surrounding an impoundment. Such impacts can
be traced to land use changes in downstream flood plains which
are offered greater protection by an impoundment project and in
areas of water use for water supply or irrigation.
Most impoundment projects incorporate major concerns for
primary and secondary impacts on water quality, land use, and
ecology. It should be realized that adequate assessment tech-
niques do not exist for all impacts, even those which can be
accurately identified and predicted. Downstream ecology can
be altered substantially by fairly small changes in flow regime,
temperature, characteristics of the stream bed, and other
factors while all the parameters addressed in applicable water
quality standards and criteria are being met. Such subtle shifts
in ecology can rarely be evaluated in economic terms. These
problems cannot be resolved readily within the existing frame-
work of environmental criteria. Such impacts should be evaluated
as fully as possible to indicate a need for a more comprehensive
environmental quality standard or further study of the impact
area significance.
The environmental effects, and feasibility of project alter-
natives should be described fully in the EIS , In the case of
multiple-purpose projects, a combination of nonimpoundment
alternatives would probably be required to meet various water
11-13
-------
o Alternative methods of accomplishing each proposed
project function. For instance, in the case of
flood control, show that adequate consideration
has been given to nonstructural alternatives such
as flood plain management or zoning, flood-proofing,
etc.
& Alternative structural components of the impound-
ment and/or alternative structural methods of
achieving project purposes
© Alternative methods outside of agency responsibility
© Rescheduling of action
® Compensatory or mitigating measures
The effort required for assessment of each alternative will
be a function of the type of alternative under consideration.
The alternative must be reviewed in sufficient detail to
identify all impact changes, whether they increase or decrease.
The review should recognize that the EIS's consideration
of alternatives will be one of demonstrating why the alterna-
tive was unacceptable. In most cases, socioeconomic considera-
tions will be a major factor. It is the reviewer's task to:
e Determine that all viable alternatives have been
considered
© Determine that their environmental effects have been
set forth adequately
© Review the alternatives from the standpoint of their
mitigation of environmental impact possibilities over
the proposed project's lifetime
II.B.5. Probable Adverse Impacts that Cannot be Avoided
The probable adverse impacts that cannot be avoided will
be the basis for the overall assessment and rating of the project.
11-15
-------
For each alternative considered, the reviewer should
summarize the probable adverse impacts and relate the adverse
impacts to the proposed project and other alternatives. After
all alternatives have been considered the reviewer should be
able to determine whether the proposed project both minimizes
the environmental impact over all other alternatives and is
within acceptable environmental impact limits.
Although these guidelines are concerned mainly with the
primary pollutant impacts, to the extent possible the project
assessment rating also should include consideration of secondary
pollutant impacts. The crux of the review assessment is to
insure that the EIS contains sufficient information to "explore
alternative action that will avoid or minimize adverse impacts
and to evaluate both the long and short-range implications of
proposed actions to man, his physical and social surrounding,
and to nature.
II.B.6. Relationship of Short-Term Uses vs Long-Term Productivity
3
From the Council on Environmental Quality guidelines,
"This section should contain a brief discussion of the extent
to which the proposed action involves tradeoffs between the
short term environmental gains at the expense of long term
losses, or vice versa, and a discussion of the extent to which
the proposed action forecloses future options." Assessment
of impacts within this category requires that the reviewer
determine the extent of the limitations, if any, placed on
future benefits of the project area, such as:
e The effects the project will have on the natural value
of free-flowing rivers which must be considered diminish-
ing resources themselves
© The potential long-term decreases in environmental
productivity due to the artificial control of basin
hydrology for short-term economic gain
9 An evaluation of flood hazard in locating federally
owned or financed buildings, roads, and other
facilities and in disposing of federal lands and
properties (i.e., review of E011296)
11-16
-------
II.B.7. Irreversible and Irretrievable Commitments to
the Proposed Project
The intent here is to determine that the environmental
impact statement has identified properly "the extent to which
the action irreversibly curtails the range of potential areas
of the environment." Especially noteworthy are the effects
associated with connecting a free-flowing river to an arti-
ficially managed water body and the potential commitment of a
river's flood plain for surface water use and general develop-
ment. Assessment in these areas, if well posed, can provide
significant inputs to the EPA review response.
II.B.8. Other Interests and Considerations of
Federal Policy
The CEQ Guidelines refer to such Federal policies
that are "thought to offset the adverse environmental
effects of the proposed action." EPA reviewers should,
however, consider the project from the standpoint of all
Federal policies for which EPA has primary responsibility.
Most of these policies are, of course, contained in EPA's
legislative authority and implementing regulations. Other
sources of EPA policy are contained in the Administrator's
Decision Statements, the 309 Review Manual, and the
notebook containing Policy and Guidance documents compiled
by OFA. The OFA Policy and Guidance notebook provides
guidance on a number of policy areas which are under the
cognizance of other Federal agencies, but which nevertheless
impact EPA programs. Laws relating to such policy areas
include the Coastal Zone Management Act, the Endangered
Species Act of 1973, the National Historic Preservation
Act of 1966, E.O. 11296, and the Fish and Wildlife
Coordination Act. All but the last two areas are specifically
discussed in the OFA Policy and Guidance notebook.
11-17
-------
II.C. Pre-Final Impact Statement Consultation
Efforts should be maintained to follow up and work with
agencies which have submitted draft EIS's that are rated with
categories ER, EU, or 3, so that they are improved at the
final stage. At the request of the principal reviewer,
appropriate EPA personnel should meet with officials of the
initiating agency to discuss EPA's comments, provide additional
information, and to recommend means to improve the proposed
action, and supporting EIS. Meetings conducted at the Head-
quarters level shall be coordinated by OFA. If an agency
requests an EPA position on a proposed final EIS, the principal
reviewer may acknowledge tentative concurrence or nonconcurrence
with the agency's response to EPA's comments on the draft EIS.
Care should be taken to avoid written statements that can be
taken as an EPA endorsement of an action or objection to an
action on nonenvironmental grounds.
SCS has requested that EPA be available to provide an
evaluation of its response to the EPA comments on draft EIS's
not rated "LO." Complying with SCS's request for an EPA posi-
tion on proposed final EIS's (for drafts rated ER, EU, or 3),
responses to their comments should be made within 30 days of
receipt, provided that the EPA concerns have been adequately
resolved in pre-final consultation. The reviewer should
acknowledge EPA's tentative concurrence with SCS's response to
the comments on the draft through a letter subsequent to the
pre-final EIS consultation. If the EPA concerns cannot be
resolved with SCS during pre-final consultation, the normal
final EIS review procedure should be followed.
A follow-up on EPA's comments on draft EIS's relating to
permits under consideration (for issuance pursuant to Section
10 of the Rivers and Harbors Act of 1899 and Section 404 of the
FWPCA) is especially important because of the Administrator's
responsibility under Section 404(c). Principal reviewers
should determine whether the final EIS contains sufficient
information to provide a basis for the exercise of the
Section 404(c) responsibility.
11-18
-------
II.D. Review of Final EIS
For each draft EIS which was rated category 2, 3, ER, or EU,
the final EIS will be reviewed to determine whether the state-
ment substantially resolves the problems surfaced by the
draft EIS. The principal reviewer will consult and coordinate,
as necessary, with those EPA offices included in the review of
the draft EIS. In reviewing the final EIS, primary attention
should be directed to substantive issues related to assessing
the environmental impact of the proposed action.
The principal reviewer must also review the final EIS
where the Agency's draft EIS comments were rated 2 or 3 to
ensure that the originating agency provides sufficient infor-
mation for a comprehensive review of the final EIS. It is
necessary that the review of the final EIS be effected in an
expeditious manner. The comments generated by EPA must be
issued within the 30-day deadline. Thirty days is the period
the initiating agency must wait before taking action on the
proposed project.
11-19
-------
II.E. Project Follow-Up
After completion of the reviews of an EIS, the principal
reviewer should conduct a post-EIS follow-up where the EPA
determines that the proposed action, as reflected in the final
EIS, contains environmental reservations, or is environmentally
unsatisfactory, or that the final EIS is unresponsive. The
principal reviewer should effect post-EIS liaison by preparing
a plan of action and submitting this plan to OFA for Head-
quarters comment and coordination. (See Transmittal 2 for
procedural requirements). In carrying out his post-EIS follow-
up responsibilities the principal reviewer shall ensure that he
coordinates his activities with the responsible initiating
agency official, appropriate state and local environmental
protection officials, and other EPA officials. These officials
will include, among others, regional or state enforcement
officials for NPDES permitting, regional enforcement officials
for Section 404 enforcement, and regional air program officials
for transportation control strategy compliance and state imple-
mentation plan requirements.
In the long term, a project follow-up will consist of the
review of Operation and Maintenance EIS's. These EIS's are
written for large in-place impoundments and should include a
description of the releases from the dam as well as the manage-
ment of the recreational developments, fisheries, and land use
plans of both Federal, non-Federal, and other responsible
agencies.
11-20
-------
Table II-l. Impoundment Review Checklist
I. Review the Project Environmental Setting
Issue: What is there now? What are the
baseline conditions?
Physical
0 Topography
0 Soils and geology
00 stability (slides and slumps)
0 0 earthquake potential, geological evolution
0 Basin geomorphology
Cultural
0 Land use
00 commercial, industrial, residential
00 forestry
00 mining
00 agricultural
00 recreational
00 aesthetic: wilderness, scenic, open space,
parks, unique physical features, historical
and archaelogical sites
Biological (flora and fauna)
0 Aquatic
00 endangered species
00 unique ecosystems
00 fish and shellfish, including migration routes
and spawning areas
11-21
-------
00 benthic organisms
00 insects
00 microfauna, microflora
00 aquatic plants
0 Terrestrial
°0 endangered species
00 unique ecosystems
00 range and habitat, migratory patterns,
barriers, and corridors
00 vegetation: trees, grasses, shrubs, crops
° Wetlands
00 relation to aquatic, terrestial habitat
00 type and value
Hydrological
° Climate
° Flows, floods (highest and lowest, recurrence
intervals)
° Erosion and sediment production, deposition
0 Geohydrological
00 aquifer location and extent
08 recharge characteristics
° Water quality
00 existing uses
00 existing levels of water quality parameters
c Rainfall-runoff/snow - snow melt characteristics
° Estuaries
11-22
-------
° Floodplains and wetlands
II. Review the Project Characteristics
Issue; What is this project for? What will it do?
What does it look like?
Physical
° Impoundment morphometry
° Size: height, acre-feet, conservation levels,
flood control pools
° Construction techniques
° Auxiliary systems: roads, transmission lines,
boat ramps, power houses
Functions
° Single purpose
00 flood control
00 navigation
00 water quality
00 recreation
00 water supply
00 irrigation
0 Multi-purpose
Economics
0 Demand studies: bases for project need
0 Supply studies: ways to meet identified needs
00 alternative projects
- structural
- non-structural
11-23
-------
0 Project life
° Benefit/cost analysis
° Application of Water Resource Council Principles
and Standards
Operating Characteristics
0 Schedule of releases for each project function
° Design
00 outlet levels
00 reaeration procedures
III. Review Environmental Impacts of Project
Issue: How will completion of this impoundment
project (described in II above) affect
the environment (described in I above)?
0 Review the predicted effects of the proposed
impoundment on the environmental characteristics of
the river basin: Physical, cultural, biological,
hydrological (I above).
0 In particular, review:
00 Projected changes in water quality parameters
resulting from impoundment construction
and operation
- in the impoundment itself
- in downstream reaches
00 Projected changes in uses (e.g. aquatic biota,
water supply, recreation) resulting from
charges in water quality parameters.
- in the impoundment
- in downstream reaches
00 Projected charges in land use, such as a shift
from low intensity (agriculture) to high intensity
(industry) uses on the flood plain.
11-24
-------
- effect on wetlands, aquatic and terrestial
habitat
- effect on water quality management planning
- effect on air quality maintenance planning
* Review predictive modeling techniques for:
00 reasonableness of assumptions
00 technical validity
00 predictive reliability 1
00 sensitivity analysis under differing assumptions
0 Review alternatives
00 design
- impoundment size
- operating policy
- operating design (e.g. multi-level outlets)
00 non-structural
- no project
0 Review mitigation measures
00 design modifications
- aeration of releases
- destratificationj hypolimnetic aeration
- multi-level outlets
Review Project Impacts for Consistency with Federal
Environmental Policy
Issue: Does the severity of the environmental impacts
(described in III above) of the project render
it inconsistent with the objectives, standards,
or implementing procedures of Federal
environmental policy?
11-25
-------
° Review EPA legislative authority
00 Is project consistent with legislated
environmental objectives and policies?
00 Is project consistent with regulations imple-
menting environmental objectives and policies?
00 Will the project lead to standards violations?
0 Review consistency of project with environmental
planning efforts
00 Is project consistent with State Water Quality
Management Plans?
00 Is project consistent with Air Quality Maintenance
Plans ?
0 In particular, review consistency of project with
environmental requirements most likely to be
affected by impoundment projects.
00 Water quality standards
- flow requirements
- water quality criteria
- designated water quality uses
- anti-degradation policy
00 Section 313 (Federal facilities) pollution
control
00 Section 404 (Dredge and Fill). If disposal of
dredged or fill material is involved, review
for compliance with 404 Guidelines (40 CFR 230)
- wetlands
- municipal water supplies
- fisheries and shellfish beds
- wildlife
- recreational areas
11-26
-------
00 Administrator's Decision Statement on Wetlands
0 Review project under related Federal environmental
requirements
00 Conformance with NEPA requirements and CEQ
Guidelines
00 Conformance with Water Resources Council's
Principles and Standards (if applicable)
00 Conformance with:
- Coastal Zone Management Act
- Endangered Species Act
- Fish and Wildlife Coordination Act
- National Historic Preservation Act
0 Review project in terms of mitigation measures
(including alternative projects and delayed
construction) which could reduce the adverse
environmental effects of the project
00 Mitigation measures available to reduce adverse
effects should be fully utilized.
11-27
-------
Table 11-2. Impoundment Impact Checklist
Page
Reference in
Topic
Chapter IV
Construction Phase Impacts
Sediment pollution and stream siltation
14
Pesticides, petrochemicals, and other potential
pollutants
14,15
Quantification of erosion and sediment generation
25
Relevant criteria for sediment pollution
47
Protection of water quality during construction - general
47,48
Erosion and sediment control techniques
48,49
Treatment of polluted water from construction site
51
Activity scheduling
56
Components of solid waste from construction operations
66
Disposal of chemicals and containers
68
Summary of solid waste impacts
72
Air pollution sources at construction sites
73
Noise generators at impoundment construction site
78
Typical construction noise levels
80
Rough estimation of noise impacts
81,82
Damaging effects of noise
85
Impacts in Impoundment
Probable land use impacts
1,2
General methodology for evaluating land use changes
and impacts
3,4
Loss of stream and bottom land
4,5
Relocation impacts
5
Recreational development - general
5,6
Secondary air pollution impacts (parking facilities)
77
Solid waste generation at recreational areas
69,70
Impact of land inundation on impoundment water quality
16
Organic decomposition and dissolved oxygen deficiency
16,17
Solution of iron and manganese
17
Loss of wildlife habitat
17,35,36
Assimilative capacity changes - general
Primary determinants
17
Critical water quality conditions
18,19
Effects of stratification and density currents
18,19
Eutrophication and associated impacts
19
Consideration of evaporation
20,35
Shift from river to lake environment and reduction of
species diversity
20,36
Sedimentation in impoundment
21
Modelling of impoundment water quality
25,26
Estimating significance of site conditions with respect
, to impoundment water quality
27,28
| Potential for erosion in reservoir
28,29
IT-7R
-------
Table II-2. Impoundment Impact Checklist
(Cont'd)
Page
Reference in
Topic Chapter IV
Impacts in Impoundment (Cont'd)
Relationship of morphometry to potential eutrophication
and weed problems
30-33
Nutrient sources and loadings
30-33
Quantification of influent water quality
32
EPA responsibilities for point and nonpoint pollution sources
32,33
Probability of water quality problems in stratified reservoirs
33,34
Evaluation of reservoir fisheries
51-55
Summary of water quality parameters that may be affected
by impoundment and relevant criteria
52,53
Thermal criteria for fisheries
54
Downstream and in areas of water use
Influence of land acquisition policy on reservoir development
5-7
Induced development in region
7
Land use impacts due to increased flood protection
7,8
Land use impacts of irrigation impoundments
8,9
Evaluation of water pollution from irrigation
8,9
Policy concerning use of flood plains
10
Prevention of water quality degradation from irrigation
projects
9-12
Impact of water quality changes on downstream biota
23,24
Impact of dam as barrier
24
Flow regime changes - general
37
Quantification of hydrographic modification
38
Seasonal and diurnal flow variations
39
Minimum release requirements
39,40
Low-flow augmentation analysis
40
Effects on riparian vegetation
40
Flow requirements for salmon and other species
41,42
Temperature changes - general
42
Important categories of fish species
42,43
Effects of outlet location and impoundment operation
43,44
Possible thermal effects on downstream species composition
44,45
Thermal criteria for fisheries
54
Effects on downstream uses
60-62
Alternatives for mitigatinq impoundment and
downstream water quality impacts
Reservoir clearing
55,56
Removal of soil and organic matter
56
Selective withdrawal
57
Turbine aeration
62,63
Howel1-Bunger valves
63,64
Destratification and hypolimnetic aeration
64,65
-------
III. PROJECT RATING
The basis for the EPA comments on the environmental
impact of impoundment projects is quite broad. As stated in
the Clean Air Act, Section 309(a), EPA comments on "...any
matter relating to duties and responsibilities granted pursuant
to this Act or other provisions of the authority of the
Administrator...." The NEPA, section 102(2) (C) states
"...the responsible Federal official shall consult with and
obtain the comments of any Federal agency which has jurisdic-
tion by law or special expertise with respect to the environ-
mental impact involved."
The above mandates have been interpreted to mean that
the EPA comments should be related to the impact of projects
on water quality, air quality, solid waste management, noise,
radiation control, and pesticide and other toxic substances
use and control. Water quality concerns include protection
of beneficial water uses, wetlands, aquatic life and habitat,
and water-related wildlife. Comments related to land use,
terrestrial wildlife, aesthetics, recreation, and other areas
must be related to areas of expertise. It is proper to
discuss residential or industrial development that an impound-
ment project may induce if it will aggravate an already serious
air or water pollution problem. It is also proper to evaluate
the potential for downstream development in floodprone areas
as a result of flood control impoundments as well as the
extent to which projects benefits assigned to flood control
include such projected development.
If an EPA reviewer has special insight on a project,
such as that resulting from an on-site inspection or discus-
sion with community leaders, it is appropriate to make comments
on matters falling outside of EPA's specific areas of juris-
diction. The EPA policy is that such comments are for informa-
tion only and are not used to justify the assigned EPA rating.
Furthermore, such comments must include a statement to the
effect that final determination on the matter is deferred to
the Federal agency with the appropriate jurisdiction.
The specific bases for the EPA assessment of environmental
impacts consists of the standards, criteria, EPA policy
decisions, and consistency requirements with other EPA program
responsibilities as shown in Table III-l.
IIl-l
-------
As detailed in the 309 Review Manual, the EPA rating
scheme is different for draft EIS's, final EIS's, and
pre-Clean Air Act Amendments EIS's. At the draft stage
comments shall be designated by an environmental impact
rating of LO (Lack of Objections), ER (Environmental
Reservations), or EU (Adequate), Category 2 (Insufficient
Information), or Category 3 (Inadequate). If a draft EIS
is assigned a Category 3, normally no rating will be made
on the environmental impact of the proposed project or action
since a basis does not generally exist on which to make such
a determination. When there is a basis for assessing the
environmental impact of a proposed action, such as independent
documents or on-site surveys, such a rating may be established
at the discretion of the principal reviewer after consultation
with OFA.
At the final stage, no alpha-numeric designations are
made since only the project impact is considered and not the
completeness of the EIS. The project impact rating assignments
for the final EIS consist of Lack of Objection, Environmental
Reservations and Environmentally Unsatisfactory. A rating
assignment of Unresponsive Final Impact Statement can be made
if the final EIS has not responded adequately to comments made
by EPA on the draft EIS. Such comments may also be offered if
new environmental concerns have been brought to the EPA's
attention since the review of the draft EIS and the originating
agency does not adequately evaluate these factors in the final
EIS. In the case of projects which were authorized prior to
passage of the Clean Air Act Amendments (December 31, 1970),
the determination of Environmentally Unsatisfactory shall not
be used. Instead, the final EIS comment should present
EPA's substantive comments on the project, omitting both
reference to Section 309 and use of the term, Environmentally
Unsatisfactory.
The general criteria for assigning the Environmental
Reservations, Environmentally Unsatisfactory, or Category 3
ratings are given in Table III-2. The reviewer should note
that these criteria are intended to be used as guidelines
rather than strict rules. The decision regarding the impact
of each project must incorporate all the mitigating factors
for that particular project. The sensitivity of the impoundment
environment to the changes imposed by the project, as well as
the effectiveness of mitigating measures, must be taken into
account.
III-2
-------
Table III-l. Standards, Criteria and Regulations
Related to Impoundment Projects
Standards
° Latest version of primary drinking water standards
prepared by EPA pursuant to the Safe Drinking Water
Act (PL 93-523)
0 Water Quality: State adopted water quality standards
consisting of designated use and water quality criteria
and plans for the enforcement and implementation as
referenced in 40 CFR Part 120 and 130.17
° Air Quality: National primary and secondary ambient
air quality standards as specified in 40 CFR Part 50
Criteria, Regulations and Policy
0 Criteria for Water Quality, Volume 1 (Proposed)
U.S. EPA, October 1973
° Water Quality Information, Volume II (Proposed),
U.S. EPA, October 1973
0 Information on Levels of Environmental Noise Requisite
to Protect Public Health and Welfare with an Adequate
Margin of Safety, U.S. EPA, March 1974
° Regulation for the Disposal and Storage of Pesticides
and Pesticide Containers, 40 CFR Part 165
° EPA Policy to Protect the Nation's Wetlands,
Administrator's Decision No. 4
° Navigable Water, Procedures and Guidelines for Disposal
of Dredged or Fill Material, 40 CFR Part 230
° Latest regulations prepared by EPA pursuant to Section
1424(e) of the Safe Drinking Water Act regarding Federal
projects in a recharge area of an aquifer designated as
a sole source aquifer
° Amended FIFRA Act. The Federal Environment Pesticide
Control Act of 1972 (FEPCA)
° Policy on Storage and Releases for Water Quality Control
in Reservoirs Planned by Federal Agencies, 16 January
1973 (two enclosures) and amendment, 31 October 1973
° Implementation of Policy on Storage and Releases for
Water Quality Control in Reservoirs Planned by Federal
Agencies, 7 February 1973
° Thermal Processing and Land Disposal of Solid Waste
Guidelines, 40 CFR, Parts 240, 241
Consistency with Other EPA Programs
° Areawide Waste Treatment Management Planning Areas
("208" Plans), 40 CFR Part 126
0 State and Areawide Water Quality Management Plans,
40 CFR Parts 130 and 131
0 National Pollutant Discharge Elimination System,
40 CFR Part 125
° State Air Implementation Plans, 40 CFR, Parts 50 and 51
III-3
-------
Table III-2. Rating Impoundment Projects
General Criteria
(from 309 Review Manual)
Category EU
a. Where it is highly probable
that a violation of standards
will occur.
1. Federal, State, and local
standards are included;
includes EPA regulations
and guidelines.
Specific Criteria
for Impoundments
Category EU
° Violations of water quality
standards, including
noncompliance by Federal
facilities with requirements
for pollution abatement and
control (section 313);
00 violations of water quality
criteria defining uses
designated in standards;
00 violations of flow require-
ments required by water
quality standards;
00 violation of State anti-
degradation provision
or EPA's anti-degradation
policy;
00 violation of State mixing
zone policy.
° Violation of informational
guidelines, such as those
for non-point source control
(304 (e) ) .
0 Unacceptability under FWPCA
Section 4 04, i.e. impoundment
projects for which EPA has
denied a permit under 404(c)
for reasons relating to water
supply, shellfish beds and
fishery areas, wildlife, or
recreational areas.
III-4
-------
2. Projects which as "an initial
step do not violate standards,
but inherently create signi-
ficant pollution problems
in related areas."
0 Projects which, with high
probability, will lead to
undesirable growth rates
adversely affecting the
attainment of air quality
goals in critical Air
Quality maintenance areas
or water quality goals
established through State
Water Quality Management
Plans (Section 208, 303).
° Projects which will not
"stand along," i.e. those
for which full realization
of benefits strongly
implies further system
development which, taken as
a whole, would lead to
standards violations or
"undesirable growth rates"
described above.
Where a Federal agency violates
its own substantive environmental
requirements.
Where .there is a violation of an
EPA policy declaration.
d. Where there are no applicable
standards or where applicable
standards will not be violated
but there is potential for
significant and severe
environmental degradation:
(1) which could be mitigated
by other feasible
alternatives; or
As applicable.
° Violation of EPA's Statement
of Policy on Protection
of Nation's Wetlands
(38 FR 10834) .
° Violation of EPA policy
regarding 102(b) of the
FWPCA.
0 Where adverse environmental
effects are beyond EPA's
jurisdiction and expertise
(e.g. historic site,
wild and scenic rivers),
but there exists a feasible
alternative (i.e. one that
would substantially
accomplish project purposes)
which would significantly
reduce adverse environmental
effects.
III-5
-------
(2) which relates to EPA's
area of jurisdiction
or expertise.
° Where severe adverse
environmental effects are
within EPA jurisdiction
and expertise but no stand-
ards violations are
expected, e.g. either no
standard exists for a
particular water quality
parameter, or considerable
uncertainty regarding
project environmental
effects exist.
° Where aquatic biota,
water supply, or recrea-
tional areas are threatened,
but no 404 permit is
involved.
III-6
-------
Category 3
a. Insufficient information to
permit a reasonable review
of project features, thus
precluding evaluation of
project effects on EPA
standards, regulations,
or policies.
Category 3
0 Inadequate description of
water quality parameters
and their effects on uses
(e.g. aquatic biota, water
supply), either for the
impoundments or downstream
reach.
b. EIS's which, whether intended
or not, are overview EIS's
covering a broad class of
actions for which the
initiating agency either does
not intend to prepare
detailed project-by-project
EIS's, or where the Inadquate
rating, coupled with specific
comments, would substantially
aid the initiating agency in its
useful pro ject-by-pro ject« EIS ' s .
° Inadequate description of
project operation, purposes,
benefits and costs, con-
struction techniques, result-
ing growth patterns, and
other features necessary to
allow comparison of project
effects with area
Water Quality Management
Plans (and, perhaps, Air
Quality Maintenance Plans).
° Projects which may provide
comparisons with Water
Quality Management Plans,
but are inadequate for
determining local effects
on water quality, aquatic
biota, or other areas of
EPA jurisdiction and
expertise.
L
III-7
-------
IV. IDENTIFICATION AND ASSESSMENT OF PROJECT IMPACTS
IV.A. Review of Land Use Impacts
Land use impacts related to construction and operation of
an impoundment may not be limited to the immediate project area
and may vary depending upon the purposes of the impoundment.
It is critical that the scope of the EIS is broad enough to
cover significant secondary land use effects which may be ex-
perienced downstream or in other locations. The primary focus
of the review should be on the expected environmental impacts
of land use changes following impoundment construction and on
the significance of the affected natural resources.
IV.A.1. Sources of Impacts
The impacts of an impoundment on land use may be associated
with three different zones within the project's area of in-
fluence, namely, the reservoir area itself, the immediate
vicinity of the impoundment, including surrounding communities,
and the region that benefits from the project's functions and
purposes. Identification and quantification of impacts become
increasingly difficult in areas directly affected by, but
geographically removed from, the project site. Guidance for
impact assessment becomes less definitive and precise when deal-
ing with impoundment-induced impacts on land use. Some land
use impacts within an impoundment's area of influence are in-
cluded in the following sections.
IV.A.1.a. In Impoundment
Impoundment construction necessitates acquisition and
removal, from existing uses, of a certain amount of land area
and natural stream. A number of environmental and socioeconomic
impacts, both primary and secondary, may be associated with
land conversion for a reservoir:
e Loss of freely flowing stream and associated recrea-
tional opportunities
® Alteration of aesthetic values
© Displacement of families
o Loss of flora and fauna
© Change in aquatic biota characteristics
IV-1
-------
° Increase in employment during construction
° Loss of agricultural land and farm revenues
0 Loss of forest land and timber production
0 Loss of wetlands
0 Increase in lake-related recreational opportunities
0 Loss of archaeological resources
0 Loss of historic sites
0 Loss of wildlife habitat (possible effect on rare and
endangered species)
0 Effects on water quality and possible effects on
applicability of existing water quality standards
IV.A.l.b. In Vicinity of Impoundment
Land use changes and related impacts in the area surround-
ing an impoundment depend largely on the characteristics and
purposes of the project. The following are examples of im-
pacts that may occur:
0 Relocation of transportation networks and utilities
0 Change in economic base
0 Development of concessions and recreational service
facilities
0 Development of second homes
° Change in recreational use below dam
0 Increase in traffic, noise, and air pollution
0 Increase in waste management problems
° Impacts on aquifer
° Environmental and health effects including psychological,
physiological changes and changes in life styles.
IV-2
-------
IV.A.I.e. In Impoundment Area of Influence
Possibly the greatest long-term land use impacts of an
impoundment will be felt in those areas that receive project
outputs such as flood control, water supply, irrigation, or
recreation benefits. Impacts on land use may occur in less
well defined areas in the region but it is difficult if not
impossible, to isolate the contributing influence of an
impoundment from general economic and social stimuli for
development. With concentration on areas principally affected
by an impoundment, important land use changes and impacts
include:
0 Further development of downstream flood plains
o Concentration or growth, and consequently pollution
sources, in urban or other areas receiving water supply
© Loss of natural vegetative cover on newly irrigated lands
o Impacts on existing agricultural producers and markets
a Increase in wastewater discharges
© Pollution problems from irrigation drainage and runoff
More detailed outlines of socioeconomic, land use, and
related ecological considerations can be found in publications
by Hagan and Roberts and Warner et al.
IV.A.2. Review of Impact Quantification
In the long-term commitment of land for an impoundment,
existing and potential future uses and values of the inundated
area must be put into perspective so that the magnitude and
significance of the action can be estimated. Many natural
resources and ecological values cannot be described fully in
economic terms. For these values, a reasonably accurate
determination of regional significance or uniqueness is
especially important. With respect to each category of land
or stream use in a proposed impoundment area an adequate
description of impacts should address, and quantify as appro-
priate, at least the following:
IV-3
-------
0 What is the magnitude of the resources involved
(e.g. miles of stream, acres of agricultural bottom
land, etc.)?
0 What is the supply of similar resources in the vicinity
of the project, the watershed, and the region?
0 What is the quality of the resource relative to similar
resources in the region (e.g. fertile bottom land
versus marginal agriculture nearby, good stream
fishery, highly utilized waterfowl breeding area, etc.)?
° Does the resource have special significance because of
uniqueness (e.g. historic or archaeological values,
candidate for wild and scenic river status, spectacular
scenic beauty, rare or endangered flora and fauna, etc.)?
0 Can the resource commitment be mitigated or avoided by
utilizing a different site, a change in proposed pool
elevation, or a non-impoundment alternative?
Since land commitment for an impoundment is essentially
permanent, the aspects of regional supply and quality of the
particular resource should be projected into the future, to
a certain extent, to complete the analysis. Pertinent con-
siderations to quantification of various land use impacts are
discussed below.
Loss of Stream. On both the national and regional scale,
natural, unimpounded rivers are diminishing resources. There
are only a few areas where the supply meets the demand, either
because of damming or because of water quality degradation, or
other factors that detract from the usefulness of streams for
recreation and other purposes. A continuing decrease in the
supply of natural streams also enhances the values of the re-
maining streams.
The loss of "x" miles of freely flowing stream must be
related to the availability both of other such streams in the
region and of attendant values such as stream fishing for trout
or other species, white water canoeing, or unique natural
beauty. Because of the long-term commitment of a stream
resource, it is not sufficient to quantify the environmental
impact in terms of a loss of so many visitor-days per year.
Numerous intangible impacts and costs should also be expressed,
at least through comparison with similar resources in the region.
Important points to look for in the EIS to aid this assessment are:
0 Description of stream biota and analysis of how they will
be affected by impoundment.
0 Description of other existing, authorized, or proposed
impoundments in the basin or region. If the impound-
IV-4
-------
merit constitutes only one of several projects in a
comprehensive water resources development program,
cumulative losses of natural streams may be critically
important.
@ Discussion of alternatives. The alternatives of "no-
build," construction of a smaller project, a dry-bed
reservoir, lower pool elevation, or location at a
different site might avoid or reduce stream losses.
Loss of Agricultural and Forest Land. The best agricultural
land in an area is often preempted for an impoundment site. It
is probable that the need for this land will steadily increase
while at the same time marginal lands are being brought into
production and more fertile areas lost to various types of
development. There is no way to mitigate the loss of highly
productive river bottom land that is committed to reservoir
use. The local impact of reduced agricultural productivity
can be measured and assessed by relating the amount of farm
land and the value of crops affected by an impoundment to
similar parameters of the agricultural economy in surrounding
areas. Regionally, the impact of changes in agricultural land
use due to impoundment construction may be minor and is usually
difficult to quantify. However, these impacts may be cumula-
tive .
The same comparisons for forest and timber land, pasture,
natural wetlands, and other land resources within the impound-
ment area can be used as an aid in determining their importance
near the project site.
Relocation Impacts. Relocation of residences, commercial
establishments, transportation facilities, and even small
communities are evaluated in terms of economic costs. Land
use impacts may extend into areas adjacent to a proposed im-
poundment, both directly as a result of the need for certain
relocations and indirectly from the alteration of local re-
sources. Construction or reconstruction of access roads,
highways, railroads, transmission lines and other corridor-
type utilities is commonly required at impoundment sites.
The topography along the perimeter of a reservoir often pre-
sents more difficult conditions for construction than that of
the lower valley. Adverse aesthetic and environmental impacts
may accompany relocation of such facilities and are best
addressed in rigid construction specifications for the project.
Recreational Development Impacts. Development of exten-
sive recreational facilities at an impoundment project can be
expected to result in secondary environmental impacts. It is
important that the number, type, and location of proposed
IV-5
-------
facilities, as well as projected initial and future recreation-
al use, be specified in the EIS. Intensively used recreation
areas such as campgrounds, picnic areas, and swimming beaches
experience greater environmental degradation than do hiking
trails, nature study areas, and other sites receiving less
heavy use. Localized traffic congestion, degradation of air
quality near parking lots, soil compaction, loss of vegeta-
tion, increased waste generation, and potential water quality
problems may occur and should be addressed in the EIS. Anti-
cipated visitation on peak summer weekends should also be
quantified.
Provision for recreational facilities in the project plan
may stimulate development of supporting enterprises such as
sporting goods stores, boat rentals, concessions, and other
businesses. Such development may occur near the lake shore
or in peripheral areas made accessible by existing or relocated
roads. Construction of cottages or summer homes overlooking
or along the shoreline of the reservoir may take place, par-
ticularly if the impoundment offers significant recreational
opportunities.
The same factors of supply and quality previously discussed
pertain to water-based and shoreline recreational development
at an impoundment. Some of the comments on the draft EIS for
TVA's proposed Tellico Project brought up the point that 19
other major impoundments with a total surface area of over
.80,000 ha (200,000 acres) were located within an 80-kilometer
(50-mile) radius of the Tellico site.7 it was indicated that
these impoundments could meet the demand for water-oriented
recreation and that the reservoir fisheries were underutilized.
These and similar issues should be appropriately discussed, and
quantitative data presented, in the EIS so that impacts can be
assessed fully.
Land use changes in the vicinity of an impoundment may be
influenced substantially by the amount of public land acquired
at the periphery of the project. Federal acquisition, in fee
or easement, allows close control over shorefront development
and access to the reservoir. Land to be purchased by the
government should be delineated on a reservoir map along with
the limits of the normal water surface. It is a fairly com-
mon practice among federal impoundment construction agencies
to purchase lands within a taking line at a certain elevation,
perhaps several feet above the spillway crest elevation, and to
obtain flowage easements for areas that will be only occasion-
ally inundated. Fee ownership of the reservoir perimeter may
preclude development of private shore front homes and easements
may specify compatible land uses such as agriculture or pas-
turage .
IV-6
-------
Hillside overlooks and privately owned shoreline areas may
be desirable locations for second homes or recreational enter-
prises. Subsurface sewage disposal systems that are used to
serve this type of development constitute a potential source
of nutrients and other pollutants to the impoundment. The
normal increase in human activity around an impoundment due to
recreational use, relocation of roads, new access points, and
second home development will also have an adverse impact on
wildlife habitat that, for the most part, cannot be avoided.
Some of these impacts may be avoided or mitigated by changes
to the project design.
Regional Land Use. Provision of storage for flood control
or irrigation may induce alteration of land use patterns in
downstream flood plains and in areas of water use. These
usually can be clearly identified but the actual magnitude and
importance of induced effects may be difficult to estimate.
Because of EPA's broad responsibilities for water and air
quality management programs, it is important that impoundment
related changes in land use be identified and assessed as to
their impacts on these programs and on overall environmental
quality. Projections of economic or demographic growth with
and without an impoundment are very difficult to make, parti-
cularly since water availability is usually a necessary but
not sufficient condition for growth.
Given time and resource constraints for review of an im-
poundment EIS, the data, projections, and descriptive informa-
tion contained in the statement may furnish a base from which
to assess the effects of induced land use changes. Stimulation
of further development in areas with existing water or air
quality problems may aggravate environmental degradation
or complicate attainment of applicable environmental standards.
Effects of Flood Control. A variety of information is
necessary for quantifying land use impacts for flood control
including:
® Location and description of downstream damage centers,
both agricultural and urban
® The degree of flood protection afforded by the
project
o Local or state flood plain regulations in effect
® An indication of whether damage centers have qualified
for federal flood insurance and the extent to which
landowners are utilizing the program
© General economic, demographic, and land use trends in
flood-prone areas
IV-7
-------
0 Amount of undeveloped but readily developed land
within the flood-prone area and flood hazard zone
° Degree to which projected downstream development
in flood-prone areas is part of the flood control
benefits
Development of areas subject to flooding is often
encouraged by construction of an upstream storage reservoir,
even when substantial flood risks still exist. Industries
are especially apt to locate near the river because of
the availability of process water. Growth in the downstream
flood plain can be evaluated in general teams for its effect
on water and air quality plans, and in its specific effect
on the flood plain. Specific effects include hydrological
and ecological changes resulting from the conversion of
flood plains from agricultural, or less intensive uses,
to more intensive uses, such as industrialization. The
flood plain belongs, in a physical sense, to the stream,
i.e. it is part of the stream's hydrological and ecological
regime. The conversion of flood plain to industrial use
affects that regime by destroying vegetation cover and
reducing riparian aquatic habitat. In addition, the flood
plain loses some of its natural capacity for storing flood
waters and for filtering water-borne pollutants. The
impoundment may, to some extent, mitigate the need for
these flood plain functions, but the loss of habitat is
generally irreplaceable.
Floodplain development may also affect EPA's authority
under Section 404, FWPCA {dredge and fill). While the
Corps of Engineers has primary responsibility for issuing
these permits, EPA may overrule such approvals if the
permit will have an unacceptable adverse effect on
municipal water supplies, shellfish beds and fishery areas,
wildlife, or recreational areas. Thus, where 404 permits
are involved, EPA's regulatory authority and expertise
includes several areas in which EPA has exercised little
previous jurisdiction.
Effects of Irrigation. The impacts of developing
agricultural land must be analyzed for impoundments supplying
irrigation water. The following factors are important for
quantification of environmental impacts in the area of
irrigation water use:
Amount, location, composition and drainage characteristics
of land to be brought into production, level of
water table
IV-8
-------
° Existing vegetative cover and uses of land to
be brought into production
0 Types of crops expected
0 Irrigation methods to be employed
0 Amount of return flow, discharge locations, and
general water quality of receiving stream
0 Probable salinity and other pollutant increases
and method of treatment, if any
° Secondary economic and environmental effects on
agricultural areas outside the area to which the
irrigation water is delivered (e.g., due to competitive
advantage which may be given to farmers in impoundment
irrigated lands because of cheap water)
The existing character of land to be irrigated must be
described in relation to its ecological values and physical
features. Ecological impacts will probably be less in the
conversion of an already cultivated land or pasture to a more
intensively irrigated agriculture than in altering natural
grasslands or flood plain areas. Physical features of the
area including soil type and salinity, location of the water
table, and topography will affect long-term agricultural use
and potential water quality in nearby streams. Irrigation may
increase the antecedent moisture conditions in irrigated areas
and this condition can yield increased runoff.
Water pollution from irrigated lands is generally associa-
ted with overland runoff and drainage water. Pollutants
accompanying runoff include sediments, nutrients, pesticides,
and decaying vegetation. Irrigation return flows, in the form
of drainage water, may also contain high concentrations of
dissolved solids composed primarily of ions of sodium, calcium,
magnesium, potassium, boron, chloride, bicarbonate, sulfate,
and nitrate. Present technology may in some cases be inade-
quate for predicting the quality of irrigation return flow.
The problems resulting from irrigation development are usually
confronted after-the-fact.^ Because such estimates are more
likely to be qualitative than quantitative in the EIS, only
general observations on water quality changes may be possible.
In any case, dissolved solids, nutrients, and perhaps pesticides
and suspended solids concentrations would normally increase.
IV-9
-------
It is important that present water quality and water uses
in the stream reaches that are affected by proposed increases
in irrigated agricultural land, are clearly identified and
quantified. It should be noted also that continuous irriga-
tion over long periods of time may result in elevated
groundwater levels and salt buildup to the point where crops can
no longer be grown. Most irrigation return flows are not now
treated and may not be treated (for economic reasons) in the
near future. Therefore, increases in salinity, nutrients,
sediments, and other pollutants may be expected. Good irrigation
practices can minimize the adverse impacts on the water quality
of the return flow. The type of irrigation system to be used
should be evaluated. The EIS should discuss the model used to
predict water quality, the data base used, the accuracy of the
results, the sensitivity of the model to variations in input
data and should also relate the results obtained from the
modeling to downstream water uses and standards.
IV-A.3. Assessment of Impacts
The key to assessing changes in land use and impacts is
the ability to judge the suitability of lands for supporting
the type and intensity of growth which might be induced by the
project. This means evaluating the benefits as well as the
environmental impacts of such growth. The quantities of water
made available for water supply and irrigation may be directly
converted to population or land area equivalents. Not only
the magnitude but also the probable phasing of such develop-
ment will influence how well environmental quality is main-
tained during the induced growth period. If the supply of
water to a city removes a major growth constraint, development
may proceed more rapidly than in an area not hampered by water
availability limit. Local and regional water and air quality
conditions and goals may serve as important indicators to
assess the desirability of further growth in particular areas.
The existence of pollution problems should be interpreted
as a signal that natural resources are being overutllized
and overstressed.
Extensive shoreline development may threaten water quality
and increase the potential for eutrophication in an impound-
ment. In assessing the adequacy of an EIS discussion of land
uses and impacts around a proposed reservoir, consideration
must be given to ensuring maximum protection of water and
environmental quality. Because nutrients from septic tank
leaching field systems can be readily transported through the
soil to a reservoir, public sewering of developable shoreline
areas should be evaluated. Requirements for a minimum setback
distance might also be recommended. If proposed Federal land
acquisition for the project leaves large sections of shoreline
open to private development, extension of public ownership to
further protect water quality and maintain open space may be
necessary.
iy -in
-------
In many cases development will occur downstream from an
impoundment partially due to the increased flood protection
afforded by the presence of the dam. Under Executive Order
11296 Federal agencies are responsible "to provide leadership
in encouraging a broad and unified effort to prevent uneconomic
uses and development in the nation's flood plains...." EPA
feels that it is appropriate to advise agencies on preventative
as well as recovery tactics. The EIS should provide information
on requirements for local cooperation in zoning and planning in
flood plains as well as information on health, building and sub-
division regulations. If the EIS claims flood control benefits
for structures which are expected to be located in the flood
plain below the dam at some time in the future, the project
may be inconsistent with the policies stated in Executive Order
11296. Conversion of agricultural lands, wildlife habitat
or recreation areas in flood-prone areas (for example, in
the 100-year flood plain) to urban development is environmentally
undesirable and should not be promoted by any Federal actions.
In the case of irrigation where definite modifications of
land use are more easily identified, the assessment of impacts
can be more specific. Water used in irrigation may reenter a
stream either as a point source discharge (drainage return
flow) or nonpoint discharge (surface or subsurface runoff).
The latter may be controlled best by proper land management and
good irrigation methods which includes mulching, contour planting,
terracing, careful regulation of the amount of water applied,
and suitable fertilizer and pesticide application techniques.
The salinity of the soils in areas to be irrigated has an
important influence on the water quality of return flows.
It might be feasible to avoid irrigating those areas where
soils are formed from shales or are high in natural salts
if other land is available. Any method which reduces evaporation
and transpiration losses aids also in limiting salinity increases.
Drip or "trickle" irrigation and subsurface irrigation systems,
offer a number of advantages over furrow or sprinkler systems
among which are a reduction of evaporation and resultant salt in
concentrations and a high degree of water and nutrient control.
Presently, treatment of drainage water for removal of minerals
and salts is considered infeasible except in special situa-
tions, Special situations are deemed to be where high-value
£ S3 and where
carried out in combination with the p'riductio^of'do"11 "°UM b®
SOme 0th« generating lar^ ^ounts'o?
quali^M<«»¦/
quality requirements of cerLin"^ ZVn^^
iv-ll
-------
be met. Raw water sources for public supplies should not
contain more than 250 mg/1 of either chloride or sulfate unless
no other source containing less than that concentration is
available. 1 Maximum acceptable concentrations for nitrate and
various pesticides are described in EPA Proposed Interim
Primary Drinking Water Standards. Certain industrial users
may have fairly rigid water quality requirements that may not
be met after the addition of irrigation drainage water without
extensive additional investment in water treatment facilities.
The reviewer should consult Section V of "Water Quality Criteri
for further information on water,quality characteristics and
requirements for various industrial classifications.
Any practices that result in more efficient use of irri-
gation water may reduce water quality degradation due to return
flows. Subsurface irrigation may produce comparable crop
yields with as much as 40-50 percent less water than is re-
quired with furrow irrigation.1-3 installations of lined canals
or closed conduit conveyance systems will reduce seepage losses
salt pickup, and evapotranspiration losses due to phreatophtes.
Conduits also have the added advantage of reducing direct evapo
ration losses. Tile drains designed to intercept less saline
groundwaters will minimize deep percolation losses and reduce
water quality problems due to salts . A pumpback system for
tailwater control increases the efficiency of water use and
minimizes pesticides, phosphorus, and heavy metals in the
return flows. The EIS should contain descriptions of how the
rrigation system will be operated, wnat provisions will be
-made for monitoring water use and quality at individual farms,
and how pollution from return flows will be minimized. Plans
to implement land treatment programs, and other water quality
protection measures, should be fully described in the EIS
along with the agencies responsible for implementation. The
publication "Evaluation of Salinity Created by Irrigation Re-
turn Flow," 3 discusses irrigation water quality problems and
control methods in greater detail and should be consulted if
further assessment information is needed.
IV-12
-------
IV.B. REVIEW OF WATER QUALITY AND ECOLOGICAL IMPACTS
Potential water quality and ecological impacts are basic-
ally related to the direct and indirect environmental changes
caused by the project. Three general , but interrelated, areas
of influence are the impounded water body, the river downstream
from the dam, and the areas of impoundment-related land use
change. The latter area is discussed in greater detail in
section IV.A, Land Use Impacts.
The effects on temperature, dissolved oxygen, dissolved
and suspended solids, flow, and bacteria are usually the most
important with respect to water uses and ecology. Certain im-
pacts can be expected, and described, in relation to particular
site characteristics, upstream conditions, and proposed reser-
voir operations. Quantification of impact magnitudes and
significance may be difficult, other than to say that an ef-
fect may or may not occur. Water quality and related ecological
impacts are obviously major issues for impoundments requiring
careful review and coordination with agencies having specific
interest and expertise in these areas. The guidance presented
herein may be supplemented by reference to the cited technical
publications or through appropriate program offices within EPA.
IV.B.l. Sources of Impacts
Impacts on water quality and ecology can be associated
with impoundment construction inundation of land areas, cre-
ation of an artificial lake, operational procedures, and any
water uses which influence both the impoundment itself and
downstream waters. Impacts to water quality in the impounded
water body and the river downstream from the dam should be
related to applicable state and federal water quality standards
and criteria, as discussed further in section IV.B.3.
The impact statement must recognize the existing situation
with regard to dischargers upstream. In some cases, particu-
larly with sewage treatment discharges, a higher level of
treatment may be necessary due to the dam. The cost of in-
stalling this higher level of treatment should be included in
the project cost and calculated into the benefit/cost ratio.
IV.B.l.a. Impoundment Construction
Sediment, pesticides, petroleum products, and other mater-
ials are potentially significant water pollutants at an impound-
ment construction site. These are described briefly below with
IV-13
-------
further information available in section 6.0 of "Methods of
Identifying and Evaluating the Nature and Extent of Nonpoint
Sources of Pollution."14
Sediment. A major source of water pollution at an im-
poundment site is construction generated sediment transported
primarily by water and, to a lesser extent, by wind. Erosion
of land areas disturbed by construction activities is dependent
on many factors including the characteristics of the soil, cli-
matolotical conditions, and topography of the site, particular-
ly in areas where clearing and excavation are to take place.
During the construction of an impoundment any of the fol-
lowing activities may be potential sources of sediment
pollution:
e Site preparation - clearing, grubbing
o Earthmoving (cutting, filling and stockpiling)
® Construction and removal of cofferdams or other
diversion structures or stream relocation
© Relocation of existing facilities
o Dredging
o Access and haul road construction and use
® Removal of material from borrow areas
® Rock blasting, drilling, tunnelling, or channelling
e Dam foundation preparation and placement of materials
o Landscaping and general site clean-up operations
® Sediment control pond discharges
Wash waters from processing stone aggregate and concrete
batching, placement, curing, and clean-up operations are also
common sources of sediment.
Pesticides. Depending on the type of dam and ultimate use
of the impoundment, a number of chemical compounds may be used
at the impoundment construction site. They are used to control
the growth of aquatic vegetation, kill or retard growth of
vegetation around the impoundment (dam faces), or suppress in-
sect populations (primarily mosquitoes which breed in standing
water) .
Petrochemicals. Gasoline, diesel fuel, and lubricants are
the major petroleum products used at construction sites.
-------
Potential pollution problems may occur from any of the follow-
ing :
e Storage depots (accidental spills)
© Leaky vehicles (crankcase oil, gas lines, seals, and
hydraulic lines)
® Road oiling (reduces dust)
© Disposal of waste oils onto the ground (crankcase)
® Spillage when filling vehicles
Petrochemicals are significant because they will form a
film on the water surface, are odorous, and may adversely affect
wildlife which contact the water surface.
Sanitary Wastes. The four basic methods for handling sani-
tary wastewater at the impoundment construction site are the
pit privy, chemical toilet, holding tank, and septic tank with
leaching field. None of these systems should present a pollu-
tion hazard under normal conditions provided that the facilities
are properly located and maintained. Areas with steep slopes,
high water table, poorly draining soils, and sites subject to
flooding or heavy runoff should be avoided.
Other Construction Activities. Other materials used at a
construction site may be potentially harmful if introduced into
waterways through spillage, improper disposal, or careless ap-
plication. Some of the materials and operations which may
create adverse environmental effects are the following:
Potential Effect
Activity Materials Used on Waterbody
© Cleaning masonry Usually acids Lower pH
surfaces
® Landscaping
© Other cleaning
agents, solvents
Lime, fertilizers
Kerosene, toluene,
Turpentine, etc.
Raise pH,
Eutrophication
May be toxic to
fish and other
biota
o Solid waste Solid waste Water pollution
management Floating refuse
The EIS should identify potentially toxic or hazardous chem-
icals to be used and their application rate, particularly when
used adjacent to or in waterways.
IV-15
-------
IV.B.l.b. Inundation of Land and Creation of Artificial Lakes
Replacement of a freely flowing stream with a lake environ-
ment, inundation of land, and altered hydraulic characteristics
represent the principal sources of water quality and ecological
impacts in an impoundment. Thermal stratification, sedimenta-
tion, expected land use around the reservoir, and inflowing
water quality all affect the physical, chemical, and biological
properties of the impounded water. The impacts described below
are likely to occur at many impoundment projects. The EIS should
be reviewed with adequate consideration given to these effects.
Impacts Due to Land Inundation. The nature and composition
of vegetative cover and soils within a proposed reservoir area
can influence the overlying water quality subsequent to im-
poundment. Water quality changes resulting from initial inun-
dation of the reservoir and continuing for varying periods up
to several years may affect both withdrawal (consumptive) and
downstream uses of the water. At most impoundments, even large
and deep ones, changes are likely to be evident for a few years.
Substantial depletion of dissolved oxygen, organic enrichment,
increases in iron, manganese, nutrients, dissolved substances,
and increased algae growth are just a few such changes.
These changes in water quality result from the following
processes
9 Ion exchange through the clay and humic colloids in
the soil under water-saturated conditions
® Microbiologic degradation of organic materials, which
releases dissolved materials and carbon dioxide
o Leaching of organic and mineral substances from the
soil or vegetation
® Microbiologic activity at the soil-water interface,
which depletes dissolved oxygen possibly causing
anaerobic conditions and a change in the products
of decomposition
Submergence of vegetative matter and other organic debris
such as might exist in an area used for disposal of sanitary
or solid wastes causes an oxygen demand. Microbiologic acti-
vity which, in the initial years of filling and operation, may
be sufficient to deplete dissolved oxygen or even produce an-
aerobic conditions in parts of a reservoir. In many impound-
ments the reduction of dissolved oxygen due to organic decomp-
osition and leaching alone will be significant for only one
or two years. However, the effect is the same as the addition
of an external waste source. Downstream waste assimilative
capacity or intended water uses may be temporarily impaired.
IV-16
-------
Associated with an oxygen-deficient environment at the
bottom of a newly created reservoir may be other biochemical
reactions which also adversely affect overlying water quality.
Under normal, oxygenated conditions, iron and manganese are
only slightly soluble and form precipitated complexes with
phosphate and other substances. In anaerobic waters, the com-
plexes are reduced to free iron, manganese, and phosphate in
solution.15
Land flooded by an impoundment is lost as habitat for ter-
restrial wildlife. Areas exposed by seasonal drawdown or
subject to recurring inundation from flood control operations
may have significantly reduced ecological value. Inundation
may destroy wildlife or plants of special significance because
of their rarity or uniqueness. Decomposition of organic mat-
ter and solution of nutrients are likely to create an initially
high rate of productivity in the reservoir that may decline
after several years.
Alteration of Assimilative Capacity. The creation of an
impoundment on a previously free-flowing stream can substan-
tially alter the capacity to assimilate oxygen-demanding waste
introduced either into upstream reaches above the dam or to
downstream sections. With respect to basin-wide water quality
management and planning, changes in reaeration rates, travel
times, and flow and temperature regimes within the impound-
ment's zone of influence may have far-reaching effects on
optimal waste loading and allocation.
The assimilative capacity of a water body is defined in
terms of the waste load that can be introduced without degrad-
ing the water below a minimum acceptable quality for a certain
water use. A variety of factors combine to determine the as-
similative capacity of a stream and as any of the factors
change, so does assimilative capacity. Among the primary de-
terminants are:
e Flow, which affects the amount of dilution a waste
will receive
© Stream gradient and depth, which affect vertical
mixing and turbulence
e Surface area of water exposed to atmospheric
reaeration
© Temperature, which affects the saturation concentra-
tion of dissolved oxygen and BOD reaction rate
© "Background" BOD or concentration of organic wastes
and chemical oxygen demand (COD)
IV-17
-------
© Dissolved oxygen concentrations present, which
affect gas transfer at the air-water interface
© Biological and chemical characteristics
The items listed above are interrelated in terms of their
effects on waste assimilative capacity, and all can be
drastically altered by impounding and regulating a freely
flowing stream. Altered conditions in an impoundment can sub-
stantially affect the application and basis for interpretation
of stream standards, water quality criteria, waste load allo-
cations, and other regulatory and planning devices for water
pollution control. Existing EPA-approved state water quality
standards recognize the variability of assimilative capacity
with the above-listed factors. Interpretation of the stan-
dards is generally based on the average minimum consecutive
7-day flow to be expected once in 10 years. Such low flow
generally coincides with the warmest season of the year when
water temperatures approach their highest annual levels and de-
fines the critical water quality period with respect to assim-
ilation of wastes. In general, the reviewer should recognize
that upstream sources of pollution, including both nonpoint
sources and treated wastewater effluents, will often create
poorer water quality conditions in an impounded stream seg-
ment than in an unimpounded reach.
An inflowing stream will seek its own density level in
thermally stratified reservoirs and may move as an interflow
or underflow rather than staying in the epilimnion where waste
assimilative capacity is decidedly greater.^ Such density
currents are primarily the result of temperature differences
although dissolved solids and suspended solids may also cause
density differences. If the impoundment is used for flood
control, highly turbid waters from heavy runoff may move
through the reservoir as a distinct layer at a level determined
by density. With respect to waste assimilative capacity, any
inflowing water which sinks and spreads horizontally below the
epilimnion is effectively removed from the two major sources
of oxygen replenishment, namely, reaeration by contact with
the atmosphere and photosynthesis. Oxygen depletion may also
occur in the absence of stratification.
Under stratified conditions water quality in an impound-
ment may be altered significantly with important effects on
aquatic biota. Parts of the total volume of the reservoir
below the thermocline may be uninhabitable by fish if oxygen
deficiencies develop. The magnitude of hypolimnetic oxygen
depletion may be largely dependent on productive or eutrophic
conditions in the epilimnion, since this is the level from
which dead algae and other organic matter sink adding to the
oxygen demand. Nutrients may be released from bottom sediments
IV-18
-------
when dissolved oxygen concentrations are low and then recyled
to the euphotic zone by mixing in the autumn, winter, and spring.
Eutrophication. Eutrophication is the process whereby
water bodies become enriched with nutrients, resulting in
generally undesirable changes in water quality. Excessive
growths of algae and sometimes higher aquatic plants charac-
terize a eutrophic lake or impoundment. Although numerous
elements are essential for the growth of algae, phosphorus
and nitrogen are most likely to be in limited supply in
natural waters.
The change in flow regime from a free-flowing stream to
an impounded lake results in the reduction of the assimilative
capacity of the water body. This fact, combined with the in-
undation of land rich in nutrients and/or favorable nutrient
influx conditions, may result in eutrophication of the im-
poundment. In addition, hard waters are more likely to be
eutrophic than soft waters. Portions of the reservoir may
exhibit the characteristics of eutrophic waters while other
portions may not.
Eutrophication is essentially irreversible. Although numer-
ous methods for restoring and enhancing water quality of
eutrophic lakes are being used and researched, most are remedial
and have generally limited long-term effectiveness. The poten-
tial for eutrophication as well as possible preventive measures
must be thoroughly analyzed in the EIS, since impacts asso-
ciated with eutrophication are likely to detract from the
usefulness of an impoundment. Impacts caused by eutrophication
of an impoundment include the following:
f
© Reduced water clarity
© Possible increase in water temperatures in the
surface layers, due to increased turbidity
® Tastes and odors
o Increased water treatment costs for disinfection,
filtration, and coagulation in impoundments used for
water supply
o Production of organic matter which contributes to
dissolved oxygen deficiencies in the hypolimnion,
® Nuisance weed growths that interfere with boating
and water contact sports
Other Impacts. Other possible impacts in an impoundment
are reduction of coliform bacteria and other potentially harm-
ful microorganisms, reduction of sediment load, reduction of
IV-19
-------
color, increases in salinity due to evaporation, loss of sport
fish, and alteration of species composition and diversity. If
widely fluctuating water levels are anticipated, erosion in the
drawdown zone and impacts on fish spawning should also be con-
sidered .
Impoundment of a reservoir may have the effect of creating
habitat for pool types of mosquitoes depending on construction
design, operation of water levels, and aquatic weed control.
In addition, operation of the water level of the impoundment
may be favorable to production of flood-water types of mos-
quitoes, particularly if reservoir levels are allowed to
fluctuate above normal pool level for a week or more during
mosquito breeding season. On the other hand, establishment
of an impoundment may have the overall effect of reducing mos-
quito and other anthropoid problems by flooding breeding areas.
This is particularly true where rocky fast-flowing streams (the
habitat for blood-sucking black flies) are inundated, or where
flood-water mosquito habitats created by periodic flooding of
local streams are permanently inundated and changed to a per-
manent or semi-permanent pool situation. Often low lying,
shallow, swampy areas and small ponds which are particularly
productive can be permanently eliminated by impoundment with
deep waters.
The die-off of bacteria and reduction of color in an im-
poundment are usually regarded as beneficial effects. Although
coliforrn bacteria may be carried into watercourses from soils
and vegetation in the watershed, microorganisms in sewage ef-
fluent will generally be the greatest source of bacterial
pollution.
Increases in salinity in an impoundment will require con-
sideration only for projects located in arid or semi-arid
regions where high rates of evaporation are anticipated, or
where dissolved solids concentrations in inflowing streams
are high. Salinity problems presently are of greatest con-
cern in the seventeen western states and often result from
irrigation drainage and water loss. High salinity may make
a water source unpalatable or unacceptable, from a health
standpoint, for public supply. Water with high dissolved
solids concentrations contributes to salt build-up in ir-
rigated soils, may damage plants, and must be applied in
greater quantities to maintain a salt balance.
Impoundment of a stream almost invariably reduces the
diversity of the aquatic ecosystem. The total number of or-
ganisms present is likely to be greater than in the stream be-
cause of expanded aquatic habitat in a reservoir. It is
probable that, with time, the species composition will change.
Stocking in a newly created impoundment may allow for sub-
stantial populations of the stocked fish but after the initial
IV-20
-------
stocking of fry mature, the rough fish may be able to outcome-
pete, and therefore predominate the desired species. Im-
poundments may become overpopulated with rough fish making
management for more desirable game species difficult. This
adjustment, although adversely affecting recreational fishing,
serves to maintain an ecological balance. For the most part
this situation is unavoidable.
Increased depth and decreased water velocities in an im-
poundment cause sedimentation of suspended material on the
reservoir bottom. These changes may eliminate or severly
reduce populations of benthic organisms and insects that are
adapted to a stream environment. Improved water clarity due
to sedimentation of suspended matter allows greater light
penetration, possibly enhancing productivity of an impound-
ment and stimulating growth of aquatic weeds in shallow areas.
The possibility of earthquakes may be an important matter for
discussion in some impoundments, especially those located in
areas of recent seismic activity or fault zones.
IV.B.I.e. Downstream Impacts from Impoundment Operation
Primary and secondary ecological impacts downstream from an
impoundment can be traced, essentially, to changes in physical
chemical, and biological quality and to changes in water
quantity and flow regime. Alterations of nutrient supply,
dissolved oxygen, temperature, sediment load, and flow changes
are usually the most important factors to be considered in
regard to downstream impacts. Changes in chemical and biologi-
cal water quality that take place in an impoundment will in-
fluence downstream conditions, although factors of flow, outlet
location, season, size, and morphometry of an impoundment will
also affect stream quality. The impacts described in this
section are encountered at many impoundments and they should be
addressed in the EIS.
Impacts on Water Quality and Assimilative Capacity. To a
large extent the uses of a reservoir determine the operation of
the project and, thus, the changes in the river's flow regime.
Artificial variations in flow, the quality of released waters,
hydraulic characteristics of the river, and other factors in-
fluence downstream water quality and quantity. Much of the
technical literature concerning the impacts of impoundments on
downstream waste assimilative capacity and water quality focuses
on thermally stratified impoundments which are used for, among
other purposes, the generation of electrical energy. Many
problems similar to those associated with hydroelectric power
generation may also occur at other types of impoundment projects.
Because hypolimnetic waters in deep, stratified reservoirs
are often depleted of dissolved oxygen, their release through
IV-21
-------
deep outlets or power penstocks may degrade water quality
downstream. Hypolimnetic water quality may deteriorate
progressively from the onset of stratification. By the
critical water quality period (later summer or early autumn)
low concentrations of dissolved oxygen and possibly high BOD,
iron manganese, and dissolved solids usually accompany
reservoir discharge.
The same factors causing changes in reaeration in the up-
stream backwaters of an impoundment affect the replenishment
of dissolved oxygen in downstream reaches. A zone of high
turbulence is usually created in the tailrace below a dam by
deflectors, hydraulic jump stilling basins, or other energy
dissipation devices. The short time of turbulent contact may
not be sufficient to induce significant reaeration. Below the
tailrace section, velocity decreases and depth increases, both
of which work against increases in reaeration. Kittrell?
observed that high discharge rates with deep flow and short
times of travel allowed a minimum of reaeration. Although it
is possible that a greater total quantity of dissolved oxygen
would be transferred during periods of high discharge below a
dam, the concentration of DO is of interest for protecting
downstream aquatic life and assuring good water quality for
other uses.lo Churchilll9 found that dissolved oxygen con-
centrations in the Holston River below Cherokee Dam were
consistently and significantly lower at higher discharge
rates associated with hydroelectric power generation. Such
conditions should be anticipated in impoundment projects which
create large, deep reservoirs with low-level intakes. Methods
for predicting, as well as techniques to minimize or avoid ad-
verse effects of impoundment on downstream water quality, are
discussed in greater detail in sections IV.B.2 and IV.B.3.
Besides the possibility of low dissolved oxygen and re-
duced waste assimilative capacity, other probable water quality
effects may include:
© Raising or lowering of downstream water temperatures
e Changes in nutrient and dissolved solids concentrations
& Nitrogen supersaturation (if large spillway discharges
are expected)
© Decrease in sediment load
0 Decrease of coliform bacteria
The magnitude and significance of these effects depend on
associated flow regimen variations and on downstream consumptive
IV-22
-------
and nonconsumptive uses of water. Increased water treatment
costs may be necessitated by increases in iron, algae, or
other undesirable constituents altering a stream's aesthetic
value. Major factors influencing downstream water quality changes
are the existence and extent of thermal stratification in a
reservoir, outlet location, upstream water quality, and the
extent and timing of artificial flow regulation.
Impacts on Stream Ecology. Many organisms have very
definite habitat requirements for survival, growth, and re-
production that may be affected either adversely or beneficial-
ly by construction and operation of an impoundment. When
analyzing the ecological impacts the reviewer should keep in
mind that the effects of one factor on biota may be either ne-
gated or magnified by another. Cool water releases to enhance
salmon or trout spawning may be ineffective unless the con-
comitant discharge magnitude and timing are sufficient to
provide proper stimuli and maintain suitable spawning beds.
Evaluation of probable ecological impacts is largely contingent
on the kind and amount of information presented in the EIS
about the existing ecosystem, important species, proposed
operating criteria and procedures, and future water uses above
and below the impoundment site. Ecological impacts of various
impoundment-induced changes are identified below.
o Temperature. Decrease in temperature from low-level
releases at a stratified impoundment may reduce the
numbers and diversity of fish, insects, and other
organisms whose life cycles do not conform with colder
water temperatures during the summer. Overall product-
ivity in the stream may decline due to the temperature
dependence of many chemical and biochemical reactions.
On the other hand, cold water releases may enhance a
trout fishery and other life forms that require or can
adapt to cooler water temperatures. High-level releases
may warm the stream excessively and have detrimental
effiects on some species. In particular, increases in
temperature from the release of warmer epilimnetic
waters during the summer may adversely affect coldwater
species.
© Dissolved Oxygen (DO). Reduction of DO concentrations
normally accompanies deep releases from stratified
reservoirs. The tolerance of different organisms to low
DO levels varies substantially. If channel gradient and
stream depth are such that a DO deficit persists for some
distance downstream then a shift to more pollution-tol-
erant species may occur. Low dissolved oxygen concentra-
tions would have a greater adverse impact on trout, mi-
grating salmon, and other generally valuable species
than on some warmwater biota.
IV-2 3
-------
® Nutrients. An impoundment usually reduces the total
nutrient input to downstream reaches due to utilization
by algae and entrapment in bottom sediments. The down-
stream nutrient load may deviate considerably from con-
centrations observed in inflowing waters. In particular,
discharge of nutrients may be high during stratification
if concentrations build up in the hypolimnion under
reducing conditions and discharge water is drawn from
deep parts of the impoundment. Variations in nutrient
concentrations affect autotrophic organisms such as algae
that form the basis of the food chain.
o Sediments. Reduction of sediments in water passing
through an impoundment improves water quality downstream.
This change may enhance productivity by increasing light
penetration, especially if the stream is highly turbid in
its preimpoundment state. In stratified reservoirs turbid
water may move in distinct layers which, if they coincide
with the discharge level, may cause downstream turbidity
problems over a longer time period. Depending on flow
regime, scouring of the stream channel and bank erosion
may increase as a new equilibrium sediment load is
attained. The stream reach below the dam may, in a short
time, be degraded for a considerable distance. The
stream may also be turbid for longer periods of time, and
more frequently, below an impoundment. If high flows are
significantly reduced or eliminated, sediment may deposit
on the stream bottom causing impacts on bottom-dwelling
organisms and fish spawning.
® Flow. All of the above factors may be affected by flow.
Ecological impacts depend on the timing, duration, and
magnitude of flow regime changes and coincident water
quality conditions. Within the general area of flow
regime modification, the functioning of a dam as a
physical barrier to upstream movement of migratory or
anadromous species should be viewed as a potential source
of ecological impacts.
IV.B.2. Review of Impact Quantification
It should be noted at the outset that quantification of
water quality and ecological impacts following impoundment is
a highly complex task, particularly in the case of reservoirs
that are expected to exhibit strong thermal stratification.
Numerous mathematical modelling techniques may be used for
prediction of postimpoundment water quality, both in the
reservoir and downstream. All such models have inherent limit-
ations due to the need for various simplifying assumptions
IV-2 4
-------
and the inability to verify results until data from the oper-
ating reservoir are available. Any quantitative method used
to describe flow or water quality variations for a proposed
impoundment should be identified either in the EIS or in ap-
propriately referenced planning or study reports made available
to the reviewer. In addition, and perhaps more importantly,
the degree of reliability or confidence associated with any
such estimates should be stated to avoid misinterpretation.
The time frame of analysis may also have particular importance.
If, for example, estimates of downstream releases or water
temperature are presented as monthly averages, the possibility
of significant daily, weekly or erratic deviations from mean
values because of reservoir operations should not be overlooked.
The following three sections describe the kinds of analyses
and impact quantification techniques that should be looked for
in EIS's on impoundment projects. Guidance is also given for
relating, project scope, physical features, and environmental
characteristics to the magnitude and importance of various
impacts.
IV.B.2.a. Impoundment Construction Impacts
For the most part, the potential for water pollution at an
impoundment construction site is directly related to the scale
of construction operations. Relevant considerations include
the amount of land area to be cleared and/or grubbed; the lo-
cation and size of excavation, borrow, and fill areas; the ex-
tent of highway and railroad relocations; and the scheduling
of various work items.
Numerous quantitative methodologies for determining erosion
and sediment generation can be found in the literature, several
of which are summarized in "Methods for Identifying and Evaluat-
ing the Nature and Extent of Nonpoint Sources of Pollution."14
Application of these techniques requires considerable data and
assumptions that would not generally be obtainable from an im-
poundment EIS. In reviewing potential water pollution impacts
from impoundment construction the focus should include pollution
control as well as quantification of effects. Enforcement of
definitive environmental protection specifications and appropri-
ate federal, state, and local regulations should minimize water
pollution hazards.
There are no generally available techniques for quantifying
water pollution caused by impoundment construction other than
for soil erosion. The potential for water pollution from
chemicals used at the site is a function of the scope of the
construction project and size of the stream, for example,
spillage of oil is likely to have a greater adverse impact on
IV-25
-------
water quality and stream biota in a small brook than in a large
river. Also, the larger an impoundment, the greater will be the
area of soil disturbance and quantity of various chemicals used
at the construction site.
Except in the event of direct spills to the watercourse,
chemical pollutants will often be transported along with sedi-
ments by erosion. Sedimentation due to construction may not be
evaluated quantitatively in the EIS, but should be addressed in
construction specifications limiting turbidity increases in the
stream. Estimates of process water and runoff volumes used in
the design of treatment systems for removal of turbidity or
other pollutants should be stated in the EIS and compared to
low-flow stream conditions. If projected wastewater volumes
are large relative to streamflow then pollutants contained in
process waters and runoff from exposed areas may have a signi-
ficant impact on stream quality.
Quantification of construction impacts is difficult. Know-
ledge of the magnitude of construction operations, stream
characteristics, and stream uses will help the reviewer to
estimate whether significant pollution potential exists and
whether proposed measures for protecting water quality are
adequate.
IV.B.2.b. Impacts of Land Inundation and Creation of Artificial Lakes
Generally, a number of quantitative methodologies for
predicting water quality or project facility design (such as
selective withdrawal outlets for control of downstream water
temperature and/or quality) are used to support conclusions
reached in the EIS. Predictions of reservoir temperatures and
the discharge thermal regime, dissolved oxygen, chemical para-
meters, and, for multilevel outlets, hydraulic and withdrawal
zone characteristics are often made. All of the federal im-
poundment and water-related agencies have conducted considerable
research on the effects of impoundments on water quality. Data
requirements, assumptions, applicable conditions, and the valid-
ity of results for selected reservoir water quality models are
summarized in section III of "An Assessment Methodology for the
Environmental Impact of Water Resource Projects."20 This refer-
ence discusses models for prediction of reservoir and down-
stream water temperatures, dissolved oxygen in reservoirs and
streams, and nitrogen, phosphorus, and toxic compounds. Other
authors 21-24 have described models of reservoir hydraulics and
selective withdrawal outlets as well as their relationship to
downstream water quality.
In the absence of water quality modelling studies, it is
still possible to get a reasonable indication of the post-
IV-26
-------
impoundment water quality characteristics and possible impacts
by studying: (1) site characteristics, including vegetative
cover types, soils, topography and morphometry; (2) existing
stream quality data; (3) design and operational characteristics
such as anticipated modification of natural flows, reservoir
fluctuations, depth of outlets; and, (4) project purposes and
stream and water uses. The following paragraphs discuss use of
information in these various categories in quantifying or esti-
mating potential water quality impacts at proposed impoundments.
Impacts Due to Land Inundation. For a period of from one to
several years after an impoundment is initially filled, overall
water quality in the reservoir will be affected more strongly by
the characteristics of the newly inundated bottom land area than
by inflowing water. The designated uses of the impounded water
and the stream below the dam, along with applicable water quality
criteria supporting such uses, will define acceptable limits for
those water quality constituents which would be subject to
change as a result of impoundment. If a portion of the reser-
voir storage is allocated to public water supply or low-flow
augmentation, the impounded water quality will be critically
important to the values derived from these water uses. Pursuant
to Section 102 of the FWPCA, it is the responsibility of EPA to
determine the value of flow augmentation for water quality
control for projects authorized after the Act was passed.
In order to estimate the impact of impoundment area con-
ditions on future water quality, information concerning the
location and extent of various types of soil and plant cover is
basic. Knowledge of land uses, such as presently cultivated
and abandoned agricultural fields and pasture, gives some indi-
cation of potential nutrient supplies to the overlying water
following inundation. Forest and brush land can contribute to
an overall deterioration of water quality, particularly with
respect to dissolved oxygen (DO), color and dissolved materials.
This occurs even though such lands are generally a smaller
source of nutrients for algae growth in the initial years of
impoundment than fertilized farm land. It is important that
land uses within an impoundment are fully described and quanti-
fied in the EIS, using reservoir maps to depict areas and
tabulations to indicate percentages of the total floodable area.
Agricultural land, marshes, swamps, and other areas rich in
organic matter or nutrients can be expected to degrade water
quality more than less fertile sites such as coniferous forest
areas.
Iron and manganese problems are most likely encountered
impoundment sites exhibiting a large proportion of organic
soils, such as muck, peat, and vegetative matter, in the areas
to be flooded. Such site characteristics will also influence
IV-27
-------
the initial, and perhaps the longer-term, productivity of the
impoundment since phosphates, nitrogen compounds, and other
inorganic nutrients could be released from the underlying soils.
Initially high rates of biological productivity in newly
created impoundments are characteristic of organically enriched
sites which have settling and decay of algal cells. This
condition could compound the oxygen deficiency in the lower
strata. The maintenance of reservoir fertility, after the
nutrient supply originating from inundated soils and plants is
stabilized, depends primarily on inputs from upstream sources,
recycling from accumulated bottom sediments, and the amounts of
nutrients discharged from the reservoir. Algal blooms, which
depend in part upon nutrients released from bottom material, are
capable of changing water quality more than any other single
factor.
The potential for water quality deterioration due to soils
and vegetation that will be flooded should be investigated
carefully. The reservoir soils should be classified according
to their organic content and general areal extent. An arbitrary
classification scheme could be: trace to 20 percent, mineral
soil; 20-50 percent, organic soil (muck); and 50-100 percent,
organic soil (peat).25 Additional tests should include sub-
jection of reservoir soils to water-soil contact under labora-
tory conditions to predetermine their effect per unit area on
overlying water. Recommended analyses include DO, color,
nitrate, ammonia, algal counts, and pH measurements for at
least one month.15 Soils within proposed drawdown areas will
be subject to alternate exposure and inundation and their
erodibility will influence turbidity in the impoundment. Wave
action and changes in soil pore pressures are likely to cause
sloughing or landslides, particularly on steeper, unvegetated
slopes. Such field studies and soil analyses are essential for
estimating possible water quality problems and for evaluating
the necessity of special site preparation measures beyond the
usual clearing.
The general topography and morphometry of an impoundment
may have considerable influence on its subsequent water quality
characteristics. The effect of morphometry on stratification
is most important although several other factors that bear on
water quality and related problems can be identified.
Erosion in Drawdown Zone. As a general rule, the steeper
an area subject to recurring inundation or drawdown, the greater
the threat of substantial erosion problems. From a detailed
topographic map of the proposed impoundment, an estimate of
the amount of land within the inundation-drawdown area that
could pose special stability problems can be made. The contour
map would also allow correlation of erosion-prone areas with
different flood heights and frequencies. Information on the
IV-2 8
-------
magnitude and frequency of water level fluctuations contained
in the EIS should be translatable into pool elevations and
inundated areas. The design flood, which would fill the
reservoir to or above the spillway crest elevation, may have
a recurrence interval of several hundred years. Pool stages
expected on an average of once in two to five years would
clearly define the reservoir area that might be subject to
severe erosion problems on a regular basis. The season in
which flood control operations are expected should also be
noted. Winter floods sometimes occur due to unseasonably warm
temperatures and, with subsequent refreezing before the flood
pool is drawn down, ice may be an additional erosive agent.
If much of a project's flood storage capacity is derived
from shallow inundation of flat bottomland, and steeper hill-
side areas are only rarely subject to flooding, erosion may
be less severe than at a reservoir confined largely to a
narrow valley where slopes are submerged every year during
flood control operations. If the reservoir valley is oriented
so as to coincide with the prevailing wind direction at the
site, the potential for shoreline erosion by wave action is
greater than if crosswinds predominated.
Other features of the flooding/drawdown zone, especially
vegetation and soil types, may also affect the potential for
erosion. Borrow areas and agricultural land within the flood
pool limits may be susceptible to erosion and should be iden-
tified on the reservoir map. Loose, unconsolidated soils
also erode easily, particularly if vegetation is sparse. At
some New England flood control impoundments, erosion of sandy
soils in pine-forested areas is troublesome and is compounded
by undermining of the roots, loss of trees, and further expo-
sure to erosive forces. Clay content may promote flow or slip-
page of the soil when wetted by a rising flood pool. For the
same parcel of land, heavy grass cover may offer better pro-
tection against erosion than forest cover. The factors of
slope and flooding frequency should also be considered when
viewing erosion potential at different locations in the reser-
voir .
As land in a flood control reservoir is inundated, the
saturation of soils with water adds weight and may reduce
cohesion. If the water freezes, expansive forces are exerted.
These phenomena, in addition to the direct action of wind, ice,
and waves may enhance erosion by producing conditions favorable
for localized slope failures, slumping, or sloughing. In many
instances, impoundment EIS's treat this subject in general terms,
if at all. Information on reservoir operation, topography,
soils, and vegetative cover should be available in the section
describing the project and its environmental setting. With this
data, a reasonable, site-specific estimate of at least the loca-
IV-2 9
-------
tion and frequency of potential erosion problems due to water
level fluctuations is possible. In addition to these factors,
artificial cuts and fills associated with roads, highways, and
railroads that will be abandoned in the reservoir, and subject
to inundation, may pose special erosion and stability problems.
Eutrophication and Aquatic Vegetation. The morphometry of
a reservoir will also indicate where, and to what extent, aqua-
tic weeds and algal blooms will occur and create problems for
water supply or recreation. Because sedimentation in the res-
ervoir will increase water clarity, unless algal bloom condi-
tions occur, areas of the proposed normal pool where water
depths will be less than about 5 meters (15 feet) may be sub-
ject to aquatic weed infestations. An impoundment that covers
a broad valley bottom may have far greater shallowly inundated
area than a reservoir of the same capacity located in a deep
narrow canyon. This comparison is illustrated by the area-
capacity curves for two reservoirs, Figures IV-1 and IV-2,
taken from EIS's.
Both the Crooked Creek Project and the Tellico Project
would have volumes of 400,000 acre-feet (483,000,000 cu m) at
respective surface elevations of 790 feet msl and 812.5 feet
msl. Yet, for the given surface elevations, water depths of
15 feet (5 meters) or less cover only 2,750 acres (1,110 hec-
tares) of reservoir bottom at the former, as compared with
5,400 acres (2,180 ha) at the Tellico Project. This informa-
tion can be used in a number of different ways. Besides
giving an indication of the extent of shallow areas, an area-
capacity curve can be useful in interpreting and estimating
water quality impacts associated with thermal stratification
and hypolimnetic releases. Areas identified in this way as be-
ing susceptible to weed growth should be located on a reservoir
map, where their proximity to proposed recreational develop-
ments such as swimming beaches, cottages, and marines, can be
ascertained and potential nuisance conditions identified.
Shallow areas, particularly in the upstream reaches of a
reservoir, may also be subject to heavy sedimentation and
build-up of undesirable bottom deposits creating aesthetic
and possible water quality problems.
In addition to impoundment morphometry, other key factors
which must be considered in evaluating the potential for
eutrophication include nutrient loading, presence or absence of
temperature stratification, length of stratification period,
latitude, retention time, land to be inundated, light, and
turbidity.
The major contributors to the nutrient load in an impound-
ment include nutrient-laden influent streams, the entrance of
IV-30
-------
Figure IV-1. Crooked Creek Project Area-Volume Curve
SOURCE FEOERAL"POWER COMMISSION, DRAFT ENVIRONMENTAL STATEMENT CROOKED CREEK PROJECT
NO 2628 EXHI81T H 2 MARCH~1972 fNTIS PB 207 260 Di
SOURCE TENNESSEE VALLEY AUTHORITY FINAL ENVIRONMENTAL STATEMENT TEtLICO PRO JECT VOL 2 10
FEBRUARY 1972 PG M 1 ^0 t,*JT:S P" 200 075 F
-------
runoff or seepage containing nutrients from areas surrounding
the impoundment, and the land to be inundated. Modes of
transport of nutrients into the lake include surface water,
ground water, precipitation, nitrogen fixation, dry fallout,
and wildlife. The most significant sources of nutrients
entering most impoundments by various modes of transmission
will usually be domestic wastes and/or agricultural runoff.
Information on the nutrient load as well as the morphometry,
and mean depth of the reservoir will help the reviewer assess
the potential for eutrophication.26 Depending on the conditions
at the particular impoundment, the nutrient load may be mini-
mized through regulation of pollutant sources. Reduction in
the nutrient load should result in lowering the potential for
eutrophication of the impoundment. It must be remembered that
there are a wide variety of factors which may be limiting in
an impoundment.
In order to determine the potential for eutrophication,
the EIS should provide data on the quality of the incoming
water with regard to nitrogen, phosphorus, silica, carbonate,
and organics. Upstream point and nonpoint sources of nutrients
should be identified. If water quality data indicates a poten-
tial for eutrophication of the impoundment under the existing
influent conditions, then methods of controlling nutrient input
from upstream sources and the status of current EPA control
measures should be described. If nutrient input is mostly
from nonpoint sources, the EPA has jurisdiction under section
40 2 of the FWPCA. The sponsoring agency should not place the
onus on the EPA to resolve issues surrounding sections 208 and
402 but should recognize the existing situation and present
state of the program in these areas as limitations in their
project planning. The major issues involved here include the
following:
o Nonpoint source nutrient input may originate from
septic tanks, privies, or cesspools located near the
incoming stream and seeping into it. The state's
priorities in sewage treatment plant grants in the
basin should be investigated to determine whether a
reduction in the sanitary waste input may be forth-
coming by construction of a sewage treatment plant which
would take the place of the existing inadequate treatment.
Other possible nonpoint sources of nutrient pollution
are agricultural and silvicultural runoff. This type of
pollution is difficult to control. The EPA must deter-
mine whether the nonpoint source contribution of nutrients
is controllable in a reasonable period of time. This
will involve investigation of current planning priorities
in the basin. Leaching of nutrients from surrounding
land may also contribute nutrients by seepage.
IV-3 2
-------
© Point sources which may contribute to the
nutrient load of the stream should be identi-
fied in the EIS. There should be sufficient
data on their effluents to determine the feasibility
of EPA's altering the plant's effluent discharge
limitations to require a greater degree of treatment.
Where a need exists, it may be possible to change
the permit's treatment requirements from best prac-
ticable treatment (BPT) to best available treatment
(BAT). Such an alteration of permit conditions would
decrease the base load of nutrients in the influent
stream, thereby decreasing eutrophication potential.
The EIS should provide data on development around the lake.
Specific data on the types of sewage treatment facilities and
the volume to be treated per day should be provided. All point
source discharges to the lake should be identified and allow-
ances should be made for evaporation and concentration of nu-
trients in the impoundment.
The reviewer should combine the data on nutrient input
sources and their location with the map of the impoundment to
assess the potential for eutrophication and the impoundment as
a whole. The reviewer should also attempt to assess the po-
tential for problems of algal blooms or aquatic weeds in vari-
ous areas of the impoundment. Among the factors which should
be considered are morphometry of the impoundment, drawdown
practices, thermal stratification, and flow in the section of
the impoundment being evaluated. For example, a long narrow
reservoir may exhibit the characteristics of eutrophy in the
upper sections and not in the lower sections if incoming water
is rich in nutrients.
Groundwater could also account for a significant portion of
the nitrogen loading in some lakes. Phosphorus input from
groundwater usually accounts for a smaller portion of the
phosphorus loading but may be significant.
Alteration of Assimilative Capacity. The area, depth, and
volume relationships describing an impoundment project can aid
in determining whether potential water quality and ecological
impacts have been adequately addressed in an EIS. Several
parameters such as depth, period of storage, and climate can
help determine whether thermal stratification should be ex-
pected . ^ 7
The presence of oxygen-demanding wastes in influent streams
is not necessary for oxygen deficiency in the hypolimnion of a
reservoir. There are many examples of significant dissolved
oxygen depletion in reservoirs receiving water with negligible
pollution.17 Changes in water quality that take place in the
IV-33
-------
hypolimnia of most stratified impoundments are detrimental to
uses for public water supply and recreation. These changes
may degrade downstream water quality if discharges are made
through outlets below the thermocline. Although their pre-
diction is most difficult, problems with dissolved oxygen
deficiency, tastes, odors, and high concentrations of iron,
manganese, and possibly hydrogen sulfide generation are quite
likely to occur in any reservoir that is expected to stratify
thermally and should be accounted for in the EIS.
It is not possible to specify exact numerical criteria
or guidelines for levels of influent water quality parameters
that either will or will not cause deterioration of impound-
ment water quality. However, all upstream sources of both
point and nonpoint pollution should be identified and resultant
stream quality should be compared with applicable water quality
standards. Treated effluents may be as important as other
pollution sources since conventional secondary treatment of
sewage, for instance, has relatively little effect on inorganic
nutrient concentrations. The existence of upstream wastewater
discharges, extensive agricultural land use, or large scale
forest harvesting should be a signal of possible water quality
problems in stratified or large impoundments.
The assimilative capacity of an impoundment may differ
significantly from that of a freely flowing stream because of
increased depth and surface area and decreased velocity. The
rate of atmospheric reaeration in a water body, as measured by
the reaeration coefficient, is a direct function of average
velocity and an inverse function of average depth.28 An oxygen-
demanding waste discharge entering the backwater area of an
impoundment may cause a greater depletion of dissolved oxygen
than would have occurred in the unimpounded stream. Assimila-
tion of the waste may take place over a much shorter distance.^9
Reaeration by the action of wind and waves, as well as photo-
synthesis, may counter the loss of reaeration capacity due to
turbulence and mixing. Additionally, the deposition of organic
matter as velocity decreases may cause an additional BOD exertion.
In a stratified impoundment, productivity of the epilimnion also
has a strong influence on water quality conditions in the
hypolimnion. If nutrient loadings and other factors are condu-
cive to eutrophication, the cycling of dead algae, weeds, and
other organic matter to hvpolimnetic waters may aggravate dis-
solved oxygen deficiencies and water quality deterioration.
The possibility of density flows in a stratified impound-
ment should be assessed in considering assimilative capacity
changes., If existing summer water temperatures in inflowing
streams are likely to be considerably lower than expected
epilimnion temperatures, the water may move through an impound-
IV-34
-------
ment in a layer below the epilimnion where reaeration is
minimal. These temperature differences might be due to cold
water releases from an upstream impoundment, or a particular
watershed characteristic. High-gradient, well-shaded streams
may be significantly cooler than others with flat gradients
flowing through unforested areas. Any oxygen-demanding
waste entering the hypolimnion with inflowing water will
probably contribute to lowering hypolimnetic water quality.
Evaporation. Another consideration relevant to water
quality prediction or estimation is evaporation, which may be
significant in certain geographical areas. Fairly accurate
estimates of water losses by evaporation can be made through
studies of pan evaporation and the reservoir heat budget. The
problem may reach major proportions in arid or semi-arid
regions in the West and Middle West. As an example of the
magnitude of water that can be involved, evaporation and
seepage losses from Cheney Reservoir in Kansas represent about
42 percent of river inflow and local precipitation.30-31 such
losses will result in increased concentrations of dissolved
solids both in the reservoir and downstream, as well as pro-
portional decreases in streamflow. Several Weather Bureau
atlases are useful in providing such evaporation data.
Impacts on Fisheries and Other Biota. Ecological impacts
in the area of impoundment result from both the loss of ter-
restrial habitat due to the initial filling and from the con-
tinued existence of the artificial lake. In quantifying the
short- and long-term implications of flooding an area of land,
general concepts of magnitude, quality, relative supply, and
uniqueness of the resource (as described in section IV.A.2)
should be used. The relationship of different land uses and
habitat types to the regional resource base must be logically
described if an accurate estimate of impact is to be made. The
values of an impoundment's ecological and recreational resources
should not be quantified in an isolated analysis. Instead, a
comparison with resource availability in the region should be the
basis for the analysis.
The biological characteristics of an impoundment will be
determined largely by conditions discussed previously in other
sections. These characteristics include impoundment water
quality as affected by morphometry, inflowing water quality, site
characteristics, project operational features, and the ecological
character of an unimpounded stream including species composition
and diversity. In addition, introduced or stocked species of
fish will alter impoundment ecology.
The productivity of an artificial impoundment with respect
to fisheries will be affected by many factors, but in general
will closely parallel changes in trophic status beginning when
IV-3 5
-------
the reservoir is filled. Almost all impoundments undergo an
initial surge in productivity for a few years after dam closure
and the growth of game fish populations may be rapid. It is im-
portant that proposed management of the impoundment fishery be
delineated in the EIS. In the absence of conscious management
and/or insufficient harvest by anglers, the full value of the
fishery as a recreational resource may not be realized. In
many parts of the country, there is an overabundant supply of
lake-type warmwater fishing opportunities and an undersupply
of coldwater fishing. This situation may prohibit an impound-
ment from receiving the high degree of fishing pressure normally
required to maintain and improve reservoir warmwater fisheries.
In order to establish and keep a coldwater fishery in an
impoundment, there must be adequate temperature and adequate
dissolved oxygen. Generally, trout need water temperatures
throughout the summer of less than 65°F to 70°F, at the most,
and dissolved oxygen concentrations about 5 to 6 mg/1 to sur-
vive and grow adequately. These conditions will probably not
be met in portions of the hypolimnia of many thermally strati-
fied impoundments, especially if nutrient levels either from
upstream sources or reservoir bottom land are expected to be
high. The feasibility of establishing a trout fishery in a
stratified reservoir is best evaluated after impoundment when
detailed water quality surveys can be taken in the lake. Any
benefits assigned to trout fishing in an impoundment should
be analyzed carefully with regard to suitable temperature and
oxygen requirements.
Area-volume curves for an impoundment, comparable to those
shown in Figures IV-1 and IV-2, may be of some use in estimat-
ing impoundment characteristics in relation to possible impacts
on aquatic biota. The approximate depth of the thermocline at
a proposed impoundment may be predicted or estimated in an EIS.
If not, examination of thermal stratification data for nearby
lakes or reservoirs of similar size may give a rough approxi-
mation of conditions to expect. The area-volume curve can then
be used to estimate the volume of water stored in the hypo-
limnion of the proposed impoundment. This may define, in
effect, the portion of the impoundment that will be unusable
by fish and other organisms if conditions of hypolimnetic
oxygen deficiency are expected. Continuous releases of cold
water from an impoundment with a relatively small hypolimnetic
volume may exhaust the cold water supply at some time in the
summer. As warmer waters sink from above, outlet water tempera-
tures may rise significantly. This occurrence would obviously
jeopardize maintenance of a coldwater fishery in downstream
sections..
The shift from a stream ecosystem to a lake environment
will be accompanied by important changes in the relative
abundance of aquatic organisms. Eutrophication; water level
fluctuations; and alteration of temperature, velocity, depth,
IV-36
-------
bottom characteristics, and water quality all influence the re-
sulting composition and diversity of species in an impoundment.
Many biota have narrow or well defined tolerances with respect
to these conditions. Based on an inventory of species and popu-
lations in the stream segment, the reviewer should expect the
EIS to state which species will be favored, decreased in abun-
dance, or eliminated following impoundment. Experience at other
reservoirs in the region may prove valuable for assessing the
probable decline or increase of various species. The importance
of certain fish and other biota for recreation and other uses
should be quantified in relation to the supply of the resource
in the region.
IV.B.2.C. Downstream Impacts from Impoundment Operation
Downstream impacts are closely related to impoundment water
quality, method of discharge, and changes in flow regime caused
by a project. Impacts on water quality caused by land use changes
are discussed separately in section IV.A. Downstream water qual-
ity will normally compare closely with the quality of impounded
water at the level of the outlet. Discharges from near the sur-
face would probably be well oxygenated, clear, and somewhat warmer
than inflowing water, whereas hypolimnetic releases would reflect
the possibly poorer quality water stored there.
The magnitude and importance of ecological changes vary ac-
cording to the purposes, site characteristics, size, and regional
environmental setting of an impoundment thus necessitating a case-
by-case evaluation. Flood control impoundments that do not include
extended storage for other purposes have the least effect on down-
stream flows, with little or no regulation except during potential
flood situations. Aquatic ecological impacts in downstream reaches
will probably be minor unless water temperatures are changed mark-
edly. For large multipurpose projects, operational patterns are
more complex and discharges may deviate substantially from natural
conditions. Changes in physical and chemical water quality may
complicate analysis of ecological impacts. The likelihood of
significant impacts on resident and anadromous species (if present),
productivity, and aquatic habitats increases as temperature, flow
rates, sediment load, and water quality depart further from natur-
al unimpounded conditions.
Changes in Hydrographic Regime
Impacts on Water Quality Management. The general pattern of
flow regulation by an impoundment will be largely determined by
the hydrology of the basin, project uses, and allocation of stor-
age to these uses. Artificial manipulation of streamflow may fol-
low daily cycles, as at peaking power dams, temporary or seasonal
shifts caused by flood control and flow augmentation, and a gen-
eral decrease in discharge due to withdrawal uses of water and
evaporation. Any of these may be superimposed at multipurpose
IV-3 7
-------
projects. The reservoir operating policy and resulting flow
modification will have a strong influence on the nature of other
physical, water quality, and biological impacts which occur down-
stream from the dam.32 Quantitative estimates of the degree and
timing of flow regulation at an impoundment are therefore im-
portant for comparing expected discharge patterns with preim-
poundment flows and an assessment of possible impacts.
Since withdrawal uses of water at an impoundment project,
as well as evaporation, will decrease streamflow below the
dam, the following aspects of these uses should be quanitifed
in the EIS:
© The volume of impoundment storage allocated to with-
drawal uses and corresponding reservoir elevations
e The maximum annual yield from the allocated storage
for different annual inflows (set, normal and dry
years)
© Minimum project release requirements during with-'
drawal
® Restrictions on rate of pool drawdown
e Seasonal requirements of withdrawal uses
© Projected water demands and use of stored
water in impoundment
The first two items above define the decrease in annual
streamflow, neglecting evaporation and other losses, that
could be expected from maximum water supply withdrawals un-
der various hydrologic conditions.
Minimum release requirements and regulation of the rate of
pool drawdown may often be spelled out in a contract between
the government and the water supply user. This will have an
influence on the amount of water that can be withdrawn from
an impoundment. If the impoundment is a flood control/water
supply project, discharge to the downstream channel may be
strongly influenced by regulation which takes place during
withdrawal. At some impoundments the intake or diversion works
may be completely separate from the outlet structures that
control flow downstream from the dam, while different water
uses may govern other reservoir releases.
In water supply contracts between the Corps of Engineers
and water users the government may reserve "the right to main-
tain at all times a minimum downstream release of cubic
feet per second..."33
IV-38
-------
Any special seasonal flow requirements should be fully de-
scribed in the EIS. The minimum flow may be set at a level
exceeding the design flow for downstream waste treatment plants,
but the sustained occurrence, during periods when natural flow is
substantially higher, may interfere with water quality manage-
ment. Maximum daily pollutant loads for Water Quality segments
are to include provision for seasonal variation,34 and might
have to be adjusted accordingly if water withdrawals frequently
and regularly interrupt normal downstream flows. Thermal load
allocations established under the state's Section 303(e) basin
planning program, as well as individual NPDES permits, might
have to be revised in light of significantly altered discharge
and temperature conditions.
Hydroelectric plants used to generate peak power usually
cause very large fluctuations in downstream flow, both di-
urnally and between weekdays and weekends. Cyclic discharges
related to peaking operation may reach several thousand cubic
feet per second during the daytime period of high power demand,
while flows at night or other off-peak periods may be re-
stricted essentially to leakage and local inflow. It has been
shown that aeration capacity lost at high discharge is greater
than that gained at low flow.28 The release of poorly aerated
hypolimnetic water may cause a significant reduction in down-
stream assimilative capacity even with high flows. The abrupt
changes in flow over a 24-hour period caused by power generation
may have other effects on water quality. Suspended organic
matter entering the stream at the waste discharge points may
settle, at a water velocity of less than 0.183 m/sec (0.6
ft/sec), to the stream bottom during off-peak hours and be re-
suspended when the velocity reaches 0.305 to 0.458 m/sec
(1.0 to 1.5 ft/sec).The suspension of sludge deposits in
the vicinity of a sewage outfall due to flow increases may re-
sult in a further decrease in DO. Extreme variations in flow
may cause severe scouring and bank erosion in downstream sec-
tions.
Federal law relating to low-flow augmentation has under-
gone a number of revisions, the most recent and important of
which is contained in section 102(b) of the FWPCA Amendments
of 1972. The new law, and attendant implementing policy, re-
quires that the EPA determine the value of flow augmentation
for water quality control. The policy states that flow aug-
mentation for water quality control cannot be used as a sub-
stitute for adequate treatment at the source. This may take
place at the preauthorization phase, postauthorization study
stage and during review. EPA policy and guidelines regarding
low-flow augmentation, and any earlier EPA recommendations
made during project planning, are relevant inputs to the EIS
review process. Projects for which funds to initiate con-
struction were appropriated prior to 18 October 1972 are not
subject to EPA's determinations regarding water quality con-
trol storage. Predicted impoundment water quality and the
IV-39
-------
timing and methods of discharge are especially important in
assessing low-flow augmentation. The quality of reservoir
outflow will be a major determinant of the volume of storage
needed for a certain incremental improvement of stream quality.
The issuance of NPDES permits that specify maximum daily
pollutant loadings in terms of weight, and in some cases con-
centration or discharge as well, have given the states control
over variable and increased waste discharges. This control,
if used effectively, could be an alternative to low-flow
augmentation. Regulation of downstream uses of the extra
dilution water may depend on applicable water rights such as
the riparian or prior appropriation doctrines. Further in-
formation on state water policies and special situations re-
lating to flow augmentation may be obtained from the report ,
"Legal Aspects of Water Storage for Flow Augmentation,"33 al-
though it is not reflective of new requirements under the
FWPCA Amendments of 1972. It should be noted that storage
required to offset mineral water quality deterioration
primarily attributable to irrigation must be allocated to
that purpose rather than water quality control.35
The EIS should present sufficient information on antici-
pated hydrographic modification at an impoundment project
so that probable effects on water quality management can be
identified. If the magnitude and frequency of low flows are
altered by the impoundment, or if greater variability of dis-
charge results, water quality may suffer. Since treatment
plants are typically designed for waste flows that may occur
15 to 20 years in the future the reviewer must also be able
to determine what impoundment-induced alterations in water
quality and quantity may occur within this longer time frame.
A few possibilities might be the siting of a thermal-electric
power plant near the reservoir to obtain cooling water, phased
increases in water supply withdrawals, or utilization of ir-
rigation storage over a number of years.
Impacts on Stream Ecology. Many of the ecological impacts
associated with alteration of a stream's flow pattern are
subtle and not easily quantified. Because of the interrela-
tionships of discharge with physical and chemical water quality,
ecological changes below a dam may often occur due to a com-
bination of these factors. Effects on fish spawning, benthic
organisms, riparian and stream vegetation, and other biota have
been related directly or indirectly to flow regime modifications.
The difficulties in predicting the magnitude of such impacts
become evident upon examining relevant published materials.
The guidelines presented herein are oriented primarily to
identification of probable impacts downstream from a proposed
impoundment, supplemented by quantitative information and
techniques as available.
IV-40
-------
Generally, greater downstream ecological changes should be
expected with increased deviations from the preimpoundment flow
regime since the aquatic ecosystem is adjusted to natural
seasonal variations. Ideally, the determination of discharge
recommendations should be based on quantification of the water
flow needs of the species inhabiting reaches below a dam. In
practice, these needs may conflict with the attainment of
maximum economic benefits from a project so that a compromise
must be reached. An assessment of downstream ecological impacts
should begin by noting the major features of the proposed flow
regulation schedule, including the effect of the project on
natural high and low flows and on total annual discharge. In
certain instances (such as at hydroelectric peaking power
plants) diurnal and weekly variations may be substantial. An
inventory of downstream fish species and a brief description
of other water resource projects contributing to flow regime
changes in downstream sections are also important for evalua-
tion of ecological changes.
Ecological impacts caused by reduction of flood peaks below
an impoundment project may relate to the flood plain areas, the
stream itself, and, in certain cases, to the estuary. Except
in the event of an unusually large flood, most flood control
projects are designed to keep flows below a safe channel capa-
city. In some parts of the country allowable discharges may be
higher in the non-growing season when agricultural crops
are not threatened by flooding. An impoundment may provide
protection to industries, residences, commercial establishments,
roads, farmland, and other developments in the flood plain. Un-
developed natural flood plains may exhibit unique associations
of vegetation that are tolerant of recurrent inundation during
periods of high runoff. These semi-wetland areas often drain
slowly after recession of flood peaks with large amounts of
water remaining in standing pools and infiltrating into the
ground.
In most cases, reduction of streamflow due to impoundment
will adversely affect downstream ecology while flow augmenta-
tion may have certain benefits. Frequently, decreases in dis-
charge result in increased stream temperatures. This may be
critical at certain times of the year. The flow and thermal
requirements of salmon and other anadromous species have re-
ceived the most intensive study, but the general observations
may apply also to resident or migratory freshwater fish as
well. For salmon, low water levels during migration may
cause significant delay in reaching spawning grounds because
of either low water velocities, exposure of obstructions, or
barriers in the stream channel.36 Streamflows during the in-
cubation period following spawning must be sufficient to
prevent deposition of sediment on the eggs, wash away waste
products, and prevent dehydration. Fraser3 7 describes
IV-41
-------
situations where curtailing flows may result in riparian vege-
tation encroachment on spawing areas for salmon. Many fish,
most notably trout, occupy and defend certain territories, the
size of which decreases with increasing velocity. It is prob-
able that sustained streamflow reductions may in fact reduce
the carrying capacity of a regulated river.
The EIS should provide data on both preimpoundment and post-
impoundment low flow events on a monthly, weekly, and daily
basis. Comparisons of these date will help reveal the extent
of the hydrologic modification and its effect on the downstream
communities. If the impoundment is in an arid area fed by one
or more streams, whether ephemeral or intermittent, water qual-
ity conditions at low flow must be estimated. Evaporation may
be an important consideration in these cases.
Changes in Thermal Regime
The major focus of state water quality standards and cer-
tain EPA programs is on thermal pollution and prevention of
unacceptable water temperature increases. An impoundment has
the potential to significantly raise or lower downstream water
temperatures. The direction, magnitude, and timing of such
thermal regime changes determine, in part, the biological im-
pacts that occur below a dam. Quantification or estimation
of these impacts is dependent on (1) baseline data describing
the existing temperature regime and aquatic biota, (species and
composition), (2) the expected temperature patterns under im-
pounded conditions, and (3) definition of downstream priorities
for fisheries and stream use related temperature requirements.
The following paragraphs explain the importance and use of this
information in evaluating temperature related ecological im-
pacts. Temperature patterns downstream from the reservoir can
be computed via energy budget techniques involving meterologi-
cal and hydrological information.38-39
The existing temperature pattern in and below the stream
reach to be impounded may be relatively free from human in-
fluence. It may be modified by upstream thermal effluent dis-
charges, cold-water releases from an upstream reservoir, or
land use practices, such as clearing of trees along the banks
that contribute to warming of the stream. Fish, insects, and
other biota inhabiting the stream are reflective of the parti-
cular thermal regime because reproduction, growth, and survival
of different species often depend on water temperature.
As a minimum, the EIS should present data on general season-
al variations of preimpoundment stream temperatures, such as
monthly average values, along with approximate summer maxima.
This information is valuable for purposes of comparison with
IV - 42
-------
predicted temperature patterns, estimation of fish spawning
periods, and possible temporal shifts. An inventory of fish
species in the vicinity of the project site is valuable for
characterizing the stream habitat. Important categories are:
(1) cold water and warm water game fish, whether native,
stocked, or native and supplemented by stocking; (2) nongame
fish both rough and forage species; (3) anadromous and cat-
adromous species; and (4) rare and endangered species. The
state fish and game agency or the U.S. Fish and Wildlife
Service can furnish a complete, or nearly complete, species list
if the EIS contains insufficient information (for example, only
species sought by anglers might be mentioned). The EIS should
also include information on the thermal requirements of these
organisms (see Table IV-3, page IV-54).
Prediction of discharge water temperatures for various in-
flow, storage, and discharge conditions at a proposed impound-
ment is a prerequisite to identification of downstream ecologi-
cal impacts. The process may be relatively straightforward for
single purpose projects or it might be complicated by such
factors as variable discharge elevation, thermally induced
density currents, depth of thermocline, thickness of the with-
drawal layer,, and thermal discharges to the impoundment or river
upstream from the reservoir.
If discharges are to be made from the surface layer, using
either an overflow weir or selective withdrawal gates at differ-
ent elevations according to the pool level, downstream tempera-
ture will correspond closely to that of the reservoir surface.
Both the pool surface area exposed to solar heating and flow-
through time in the upper layer will affect discharge tempera-
tures, which, during the summer and early autumn, may be signi-
ficantly higher than inflow temperature. If the normal summer
pool is not expected to stratify, the location of reservoir
outlets near the surface or near the bottom is likely to be
unimportant with respect to discharge water temperature since
such a pool would be nearly isothermal. Major changes in the
downstream thermal regime will accompany continuous or intermit-
tent hypolimnetic discharges from deep, thermally stratified
impoundments. Temperature predictions under these conditions
are most difficult, especially if water is withdrawn from two
different layers simultaneously as might be done to improve
water quality of the releases. For purposes of estimating
ecological impacts, the temperature variations in the period
from late spring through early or mid-autumn are usually most
critical. The effects of temperature variations on the eco-
logical community at other times of the year should not be
overlooked, however.
Knowledge of thermal constraints for various stream uses
is essential for impoundment projects whose operation may sub-
stantially alter or provide a high degree of control over
IV-4 3
-------
downstream water temperatures. Possibly conflicting thermal
requirements should be addressed and thermal priorities should
be established in the EIS. Most of the questions concerning the
effects of downstream temperature changes would involve the
desirability of releasing cold hypolimnetic water during the
stratified period. Specific issues that may arise include the
preservation of an existing, or creation of a new, coldwater
fishery, maintenance of existing warmwater species composition,
and releases of cold water to benefit downstream withdrawal
uses for water supply or cooling.
Low-level releases from an impoundment may cause a signi-
ficant reduction in downstream water temperatures from spring
through early summer or later. In the winter, a warming effect
may be evident when the deepest water will have a temperature
near 4°C (39°F) as opposed to inflow temperatures just above
freezing. In reservoirs with hypolimnetic outlets, altered ther-
mal regime has been implicated in the elimination or reduction of
benthic fauna as well as certain fish species for varying dis-
tances downstream. Many insect species, which are important
food organisms for fish and other animals, have life cycles
dependent on strict temperature requirements. Lehmkuhl40
observed a marked decrease in the number of species and
abundance of macroinvertebrates for a distance of 70 miles
downstream from a reservoir on the South Saskatchewan River.
He attributed the decline to hypolimnetic discharges from the
dam since the warm water requirement for hatching and growth
of the species involved was not met. Most aquatic inverte-
brates have temperature-dependent seasonal life cycles and may
not be able to tolerate major modifications of a river's therm-
al regime.
Because macroinvertebrates form an important link between
primary producers such as phytoplankton and fish in the food
chain, their reduction may adversely affect productivity of
the stream fishery. Prediction of this relationship is com-
plicated by the influence of temperature on gross productivity
and chemical reactions and the fact that nutrient inputs to
the downstream ecosystem may change due to impoundment. Hynes'
book "The Ecology of Running Waters"41 offers some information
on temperature requirements and seasonal life cycles of various
aquatic insects and may be used to develop a general estimation
of changes in species composition.
The predicted thermal regime below an impoundment will
directly affect the type, and perhaps the quality, of the
stream fishery that can be maintained. If hypolimnetic dis-
charges are planned, estimates should be made of both the
discharge temperature variation during the stratified period
and the temperature "recovery" as a function of distance below
the dam., Temperatures could be expected to rise less rapidly
IV-4 4
-------
in deep and/or well shaded streams. The cooler water tem-
peratures in the affected zone may delay or prevent spawning
of warmwater fish species and enhance conditions for trout or
other coldwater species. Changes in fish species composi-
tion due to impoundment can be quite dramatic. In a preim-
poundment survey of Beaver Reservoir on the White River,
Arkansas, 72 species and 5 hybrid combinations were reported.
Subsequent to impoundment only 29 species were collected in
the tailwater area below the dam.42 Cold tailwater tempera-
tures may also inhibit reproduction of warmwater species
without causing their complete disappearance. Certain trade-
offs may have to be made with respect to a postimpoundment
downstream fishery. In a survey of 32 projects in southern
states, 43 percent of the total tailwater miles were reported
to be marginal waters which provided little or no fishing.43
The views of the Fish and Wildlife Service, which should be
summarized in the EIS, should aid in evaluating the effects
of impoundment on the downstream fishery. Replacement of a
productive, heavily fished stream, whether warmwater or cold-
water, with a marginal, or a "put-and-take," trout fishery
that must be maintained by stocking should be considered an
adverse ecological impact even though recreational use may be
increased considerably.
In the absence of significant inputs of thermal effuents
downstream from an impoundment, the release of warmer epilim-
netic water is unlikely to have a measurable adverse effect on
an existing warmwater fishery below a dam. This mode of opera-
tion would undoubtedly create temperature conditions unsuitable
for the survival and reproduction of trout and other coldwater
species if they were present prior to dam construction.
The major changes in flow regime, water temperature, and
dissolved oxygen that may occur downstream from stratified
impoundments often overshadow the effects of other water
quality parameters. Two effects which may be extremely harm-
ful to downstream biota, but which occur only in special cases,
are supersaturation of dissolved gases and accumulation and re-
lease of hydrogen sulfide. Nitrogen supersaturation is a major
problem at high dams in the Northwest and West where heavy
spillway discharges are encountered. The phenomenon causes
gas bubble disease and often mortality in affected fish. Fur-
ther biological information is contained in "Proposed Criteria
for Water Quality," Volume I. Quantitative data and general
discussions of the problem can be found in articles by Beinin-
ger and Ebel44 ancj Boyer.4 5
Hydrogen sulfide is toxic to fish at low concentrations
(see Table IV-2., page IV-52). In some instances fish kills
have occurred downstream from dams releasing anaerobic water
containing hydrogen sulfide. It is not likely that the prob-
lem would persist for a long distance downstream if it were
IV-45
-------
to occur because mixing and aeration would disperse the gas to
the atmosphere.
Reduction of sediment load combined with release of pos-
sibly nutrient-rich water from the hypolimnion may stimulate
eutrophication downstream. Wright observed that cities with-
drawing water from rivers downstream of large impoundments
experienced taste and odor problems due to algae growth. This
necessitated additional water treatment in some cases.46
Whether nutrient increases have resulted in better productivity
of downstream fisheries is uncertain. Since temperature,
oxygen, and flow may all vary considerably, it is difficult to
separate out the effects of any one factor.
Ecological impacts due to combinations of the changes dis-
cussed above may be evident long distances downstream from an
impoundment. These far-reaching impacts often occur cumulative-
ly in basins whose water resources are highly developed for
power, flood control, irrigation, and water supply. Effects
on estuarine ecosystems and agricultural productivity in deltas,
generally linked to major flow regime and sediment-load changes,
are discussed in the report "Analyzing the Environmental Impacts
of Water Projects"32 and in the publications referenced therein.
IV.B.3. Assessment of Impacts
EPA's basic policy47 regarding the water related impacts
of impoundments is as follows:
Flow regulation practices that result in lower than
natural low flows (i.e., those which would occur
in the absence of the impoundment) or release water
of less than preimpoundment quality (e.g., zero dis-
solved oxygen) are considered to be in violation of
the antidegradation clause of the water quality
standards. During the periods when natural flows
are equal to or less than the flow values used to
design waste treatment facilities located downstream
from the site of a proposed impoundment, the rate of
discharge past the dam should be at least equal to
the rate of inflow above the dam, whether or not water
quality storage is provided.
An assessment of impacts should therefore relate identi-
fied and quantified impacts to appropriate environmental
standards and criteria and determine the need, applicability,
and effectiveness of alternative mitigative techniques.
Alternatives to the proposed project such as scope, location,
or alternative means of meeting water resource objectives,
which may or may not be addressed in the EIS, should also
be included.
-------
IV.B.3.a. Impacts During Construction
Water pollution from construction activities, although
usually of short duration, may be an important source of en-
vironmental impacts. Deposition of sediments on the stream
bed may severely reduce populations of bottom-dwelling
organisms and eliminate habitat for species that require
clean gravel or rubble for spawning. Aesthetic and recrea-
tional values of a stream may also be adversely affected by
turbidity during construction. Pesticide residuals resulting
from application in proper dosages probably will not directly
affect aquatic biota. However, some such chemicals are highly
toxic, nonbiodegradable, readily concentrated by plants and
animals, and may- have cumulative impacts. Accidental spills
of pesticides, as well as oil and other chemicals, pose the
possibility of fish kills and other environmental damage at
impoundment construction sites. Careful handling and use of
hazardous materials are necessary to minimize water quality
and ecological impacts. The discussion of pesticides should
cite standards for fish flesh as well as for water. Food and
Drug Administration standards for the marketing of commercial
fish should be applied to assessing the viability of a future
commercial or sport fishery.
Construction related impacts on water quality cannot be
quantified easily even though it is known that some pollution
will occur during the construction period. The purpose of
assessing water pollution from construction should be to
assure the use of all feasible methods for reducing or avoid-
ing pollution and maintaining water quality standards. EPA's
proposed water quality criteria specify that for freshwater
aquatic life the maximum acceptable total concentration of
suspended solids is 80 mg/1, depending on the level of pro-
tection desired. The basic rationale for this criterion is
that waters containing suspended solids concentrations in
excess of 80 mg/1 are unlikely to support good freshwater fish-
eries. Water quality standards of some states specify numeri-
cal criteria for turbidity as well as general guidelines
relating to the effects of suspended matter in watercourses.
Vermont's water quality standards require turbidity levels
not to exceed 10 Jackson Turbidity Units (JTU) for coldwater
streams and oligotrophia lakes supporting trout, or 2 5 JTU in
warm waters "as a result of any discharge or activity, except
as may result from natural conditions or as may be permitted
in accord with the conditions of a temporary pollution permit
or order of the Secretary."48 The rules further state that
Class B waters be free of pollutants that affect the compo-
sition of bottom fauna, affect the physical or chemical nature
of the bottom, and interfere with the propagation of fish.
It is important that the review be coordinated with ap-
propriate state agencies that may have specific recommendations
-------
or requirements for environmental protection during construction.
During construction of Martis Creek Dam, California's Regional
Water Quality Control Board established requirements which
limited the increase in turbidity in the creek (which is an im-
portant trout stream) to not more than 10 JTU during any one-
hour period, nor more than 100 JTU at any one time.49 The re-
quirements were incorporated into construction specifications
for the project.
Downstream uses may contribute largely to a determination
of acceptable turbidities and concentrations of other pollutants
originating at a construction site. The EPA's, "Proposed Cri-
teria for Water Quality", suggests that clarity for bathing and
swimming waters be such that a Secchi disc is visible at a mini-
mum depth of 4 feet. This corresponds to a turbidity of about
10 JTU.50 in some instances, the protection of recreational
and aesthetic values may necessitate even stricter controls than
are required for preserving fish and wildlife. Water supplies
withdrawn from the river below an impoundment construction site
may also be affected adversely by higher than normal turbidity,
perhaps to the extent that addtional expenditures or process
modifications for treatment are required.
In the construction of a dam, some excavation and earth-
moving, (and other activities) will occur in the stream or
immediately adjacent to it. A special set of criteria may be
desirable for application during constuction. The criteria
should be designed for reasonable protection of the most water
quality sensitive stream use, with perhaps some degree of flexi-
bility (for example, as in the turbidity limits for construction
of Martis Creek Dam mentioned above). For protection of water
quality in the construction period, activity scheduling and proper
location of access and haul roads, as well as land treatment and
process water treatment systems should be considered. Depending
on the particular topographic conditions, any of the following
methods of erosion control might apply: (1) minimize soil ex-
posure, (2) control runoff, (3) shield soil, and (4) bind
soil. These are discussed briefly below with supplemental
information available in "Processes, Procedures, and Methods to
Control Pollution Resulting from All Construction Activity."51
Soil Exposure. Minimizing the exposure of disturbed soils,
particularly during seasons of the year when high intensity rains
may be expected, can be best accomplished by careful timing.
Excavation and earthmoving activities should be scheduled to
minimize total exposure at any given time.
Control Runoff. Minimizing the quanity of water before it
can run over an exposed slope is accomplished by using terraces,
ditches, and dikes on upper slope areas. Rain falling directly
onto the surface may be handled by scarifying slopes to reduce
-------
the flow velocity and inducing infiltration, thereby reducing
erosion. This is accomplished with shallow grooves following
contours of the slope.
Shield Soil. Numerous types of ground cover, both vege-
tative and nonvegetative, may be used to protect exposed slopes.
Nonvegetative mulches include straw, hay, wood chips, stone,
and gravel. The erosion control effectiveness of these mulches
has been evaluated under closely controlled experimental condi-
tions. Some of these results are summarized in Table IV-1.
In these experiments, stone, gravel, and wood chips were tested
because of their general availability at construction sites.
The table may be used to determine whether specifications re-
lating to slope protection are stringent enough to avoid severe
erosion. Due to increased restrictions on open burning, small
trees, brush, and limbs from the clearing of impoundment areas
may provide a large source of wood chips for use as mulch material.
The greatest shortcoming of nonvegetative mulches is the possi-
bility of rilling. Mulching loses much of its effectiveness if
drainage becomes established in small rills rather than through
the mulch material.
Fine mesh netting, stone riprap, and impermeable materials
such as tarpaulins and plastic mats may also be used for temporary
stabilization of relatively small areas. The faces of earth dams
are commonly riprapped with stone since maintenance is reduced
considerably in comparison with sodded embankments.
Bind Soil. Vegetation such as grasses, shrubs, and other
ground cover is often used to bind the soil and minimize water
erosion. It is important that the vegetation be tolerant of
the adverse conditions expected at the site such as drought,
sun, shade, and soil nutrients. During construction periods,
fastgrcwing annual grasses, either alone, or in a mixture, with
longer-lived grasses and/or mulches may be used to provide more
permanent control. Chemical binders, usually in liquid form,
may be sprayed over exposed slopes or mixed with mulches to aid
in reducing soil loss. Due caution should be exercised when
using potentially toxic or otherwise polluting chemicals to avoid
contamination of surface and/or groundwater in the impound-
ment area.
Sediment control techniques may be necessary at an impound-
ment site in addition to the erosion control procedures described
above. Vegetative controls may be used to detain or filter over-
land runoff before sediment enters waterways. Provision for
natural or planted vegetative buffer strips between the water-
courses and borrow areas, haul roads, or other areas where soil
is exposed may aid in minimizing turbidity increases.
IV-4 9
-------
Table IV-1. Soil Losses from 5 Inches of Simulated Rain on
Denuded Slopes for Various Types and Rates of Mulch
Application Rate
Soil Loss
Percent Reduction
Mulch
(tons/acre)
(tons/acre)
in Soil Loss
None
_
39.6
Portland cement
-
32.7
17
Wood chips*
2
27.1
32
Crushed stone*
15
25.6
35
Gravel
70
14.7
63
Straw
2.3
12.1
69
Crushed stone
60
11.4
71
Wood chips
4
8.5
79
Wood chips*
7
5.5
86
Crushed stone*
135
3.5
91
Crushed stone*
240 & 375
2
95
Wood chips*
14 & 25
2
95
Rain intensity, 2.5 inches per hour; slope length, 35 feet; slope
steepness, 20 percent; soil, calcareous till beneath Wingate silt loam.
*Based on one replication; others are averages for two replications.
Source: Meyer, L.D., C.B. Johnson, and G.R. Foster, "Stone and Wood-
chip Mulches for Erosion Control on Construction Sites," Journal of
Soil and Water Conservation, Vol. 27, No. 6, November-December 1972
p. 267.
IV-50
-------
In many cases more elaborate controls are necessary, par-
ticularly where waste streams may be amenable to clarification
by physical and chemical treatment. Temporary holding basins
that allow larger particles to settle out from highly turbid
waters may be constructed at low points in the impoundment area.
Turbidity control plants have been used at impoundment sites to
treat aggregate wash water, water that collects around diversion
tunnels and other structures, and other water containing high
concentrations of suspended solids. Chemical flocculants are
often used to aid in removing fine particles. These chemicals
should not be toxic to fish, wildlife, or vegetation. Adequate
inspection should be required to insure application in proper
and safe dosages. If not specified in the EIS, these or other
techniques should be recommended for all polluted water that can
be readily collected and treated.
IV.B.3.b. Impacts Due to Creation of Artificial Lakes and Impoundment Operation
Based on EPA and state antidegradation policies, and the
guidelines in previous sections, it should be possible to assess
water quality and ecological impacts at impoundments of differing
sizes, site characteristics, purposes, and operational features.
Table IV-2 summarizes water quality criteria for various con-
stituents that may be affected by an impoundment. Individual
states may have EPA approved water quality standards prescribing
different levels for these parameters, in which case state regu-
lations would take precedence.
These standards are designed to protect and enhance both
aquatic life and stream water uses and should be the primary
basis for assessing aquatic ecological impacts as well.
Table IV-3 lists the thermal criteria for protection of
a number of important freshwater and anadromous fish during
their spawning seasons. The fish listed are considered impor-
tant because of their value for sport and commercial fishing.
Although only a few of the listed species may be found in a
given stream, their requirements are likely to govern the
desirabliity and acceptability of thermal regime modifications
caused by an impoundment project.
By comparing the thermal criteria for fish currently exist-
ing at an impoundment site with the expected temperature patterns,
the reviewer can determine which species will be adversely or
beneficially affected in downstream reaches. Special circum-
stances, such as the existence of rare or endangered species,
or other locally important species, may intorduce different
temperature requirements.
-------
Table IV-2. Water Quality Criteria for Selected
Constituents and Probable Effect of
Impoundment*
Constituent
Water
Use**
Criterion
Probable Effect of
Impoundment
Iron
WS
I
0.5 mg/1
5.0 mg/1 for con-
tinuous irrigation
Increase in anaerobic
or oxygen-deficient
hypolimnion
Manganese
WS
0.3 mg/1
Increase in anaerobic
or oxygen-deficient
hypolimnion
Dissolved Oxygen
A
WS
Vari able9
None prescribed,
preferable near
saturation
Depletion or deficien-
cy, hypolimnion, with
low-level outlets, may
persist downstream
Sulfides
(Hydrogen sulfide)
A
0.002 mg/1
May be present in
anoxic hypolimnion
Dissolved Solids
I
WS
500-1000 mg/1 for
sensitive crops
None prescribedb
May increase due to
evaporation, water di-
version irrigation, or
leachi ng
Sulfate
WS
250 mg/1
May increase due to
evaporation, water di-
version irrigation, or
leachi ng
Chloride
WS
250 mg/1
May increase due to
evaporation, water di-
version irrigation, or
leachi ng
Ammoni a
WS
0.5 mg/1
May increase in anaero-
bic or oxygen-deficient
hypolimnion, from
bottom sediments
Odor
WS
R
Essentially none
Essentially none
May be problem in hypo-
limnion due to reduc-
tion products or in
epilimnion due to
algae
Clarity
R
4 feet Secchi
disc visibility
May improve upon im-
poundment; however,
excessive algae growth
may reduce clarity
-------
Table IV-2. Water Quality Criteria for Selected
Constituents and Probable Effect of
Impoundment* (Cont'd)
Constituent
Water
Use**
Criterion
Probable Effect of
Impoundment
Microorgani sm
Fecal coliform
I
WS
R
1000/100 ml
2000/100 ml (raw
water)
200/100 ml
(waters used for
swimming or water
contact sports)
Normally significant
reduction in impound-
ment; however, in-
creases have been
observed following
drawdown after flood
control operations
Mercury
WS
.002 mg/1
May increase due to
evaporation. High con-
centrations are haz-
ardous to human health
Lead
WS
.50 mg/1
May increase due to
evaporation
High concentrations
are hazardous to
human health
Zinc
WS
5.0 mg/1
May increase due to
evaporation
High concentrations
are hazardous to
human health
*Table source should be consulted for further background information
** I = Irrigation
A = Aquatic Life
WS = Public Water Supply Intake
R = Recreational Waters
aVaries with temperature and species
^Sulfate and chloride are most troublesome components
Source: U.S. Environmental Protection Agency, "Proposed Criteria for
Water Quality," Volume I, Washington, D.C., October 1973.
IV-53
-------
Table IV-3. Maximum Weekly Average Temperature for Spawning and
Short-Term Maxima for Survival During the Spawning
Season (Centrigrade and Fahrenheit)*
Species
Optimum Spawning
Maximum
Spawning Season
Atlantic Salmon
5 (41)
18 (64)
Oct. - Dec.
Bigmouth Buffalo
17 (63)
-
Late Apr. into June
Black Crappie
16 (61)
-
Mar. - July
Bluegill
25 (77)
31 (88)
Apr., June - late Aug.
Brook Trout
9 (48)
22 (72)
Sept. - Nov.
Carp
20 (68)
31 (88)
Mar. - Aug.
Channel Catfish
27 (80)
34 (93)
Mid Apr. - late July
Coho Salmon
10 (50)
22 (72)
Fall
Emerald Shiner
23 (73)
29 (84)
May - Aug.
Freshwater Drum
21 (70)
-
Early May - late June
Lake Hering (Cisco)
4 (39)
18 (64)
Mid. Nov. - mid Dec.
Largemouth Bass
21 (70)
30 (86)
Apr. - June (North)
Nov. - May (Florida)
Northern Pike
12 (54)
-
Feb. - June
Rainbow Trout
9 (48)
26.5 (78)
Nov. - Feb.
Feb. - June
Sauger
10 (50)
-
Apr. - May
Smallmouth Bass
17 (63)
-
May - July (Ontario)
Smallmouth Buffalo
17 (63)
-
Late Mar. thru June
Sockeye Salmon
10 (50)
22 (72)
Fall
Striped Bass
18 (64)
-
Apr. - July
Threadfin Shad
18 (64)
-
Apr. - Aug.
White Bass
19 (66)
-
Apr. - July (North)
Mar. - May (Tennessee)
White Crappie
18 (64)
-
Mar. - July
White Sucker
10 (50)
24 (75)
Mar. - June
Yellow Perch
12 (54)
22 (72)
Mar. - June
*Based on 24-hour median lethal limit minus 2°C (3.6°F) and acclimation
at the maximum weekly average temperature for optimum spawning for
that month.
Source: U.S. EPA, "Proposed Criteria for Water Quality, Volume I,"
Washington, D.C., 1973, p. 165 and Appendix A.
IV-54
-------
The criteria of quality and uniqueness should be applied
to ecological resources impacted by an impoundment project,
whether they are rare or endangered species, anadromous fish,
or of special seenic, historic, aesthetic, or geologic value.
Mitigation measures cannot replace committed resources. Such
alternatives as acquisition of wildlife ranges, wetlands and
other lands; construction of fish by-pass facilities; or mini-
mization of water quality impacts should receive full consider-
ation and evaluation in an EIS.
The EIS must be responsive to water quality and ecological
impacts that will result from impoundment. There should be a
full evaluation of alternative measures for maintaining water
quality that will be as good as, or better than, that existing
prior to impoundment. Several techniques have been employed
including site preparation measures, selective withdrawal
outlets, turbine aeration, discharge aeration using Howell-
Bunger valves, and artificial destratification and hypolimnetic
aeration. These are described in the following sections with
enough detail to determine their applicability at certain types
of impoundments, the water quality problems that can be amelior-
ated, and any drawbacks and limitations.
Site Preparation Measures.
In the past, reservoir site preparation has varied from
the removal of marketable timber only, to complete clearing and
stripping of all organic soil, vegetation,'and debris. Neither
extreme is usually optimal with respect to both future water
quality protection and cost. The EIS should describe and justify
the degree of anticipated site preparation work in terms of
balancing water quality gains, recreational, and aesthetic con-
siderations against cost. The evaluation may be supported by
field investigations or may be a result of general reconnaissance,
consideration of proposed uses of the impoundment, and profes-
sional judgement.
Removal of trees from an impoundment area is widely practiced.
Its purposes include aesthetics? elimination of boating, fishing,
and debris accumulation hazards; and protection of impounded
water quality. Cases often arise where total clearing is not
justifiable, feasible, or even desirable. Standing timber, stumpsT
and other vegetation can increase fishery productivity and result
in a greater sport fish harvest. Few reservoirs are cleared up
to the gross pool (spillway) elevation, particularly if a portion
of the total storage is allocated to flood control and is used
only infrequently or for relatively short periods during high
runoff. Many Corps of Engineers' reservoirs (existing or being
planned) in the Northeast have no provision for extended storage
and are operated so as to evacuate stored flood waters and recover
T\7— e: c
-------
flood control capacity as rapidly as possible following reces-
sion of a flood peak downstream. Clearing elevation for such
projects is often chosen on the basis of the storage required
to regulate a flood of a certain frequency or recurrence interval.
This interval is sometimes taken to be five years.
Removal of stumps (grubbing), brush, herbaceous vegetation,
and topsoil may be included as part of reservoir site preparation
activities, particularly if impoundment storage is to be used
for public water supply. Such operations may involve consider-
able expense. As a result, grubbing, if done at all, is re-
stricted to higher elevations in the reservoir where drawdown is
frequent. Removal of all stumps, roots, and topsoil tor a mar-
ginal 20 feet has been recommended.52 Taste, odor, and other
objectionable characteristics in water supplies may be avoided
or lessened by the removal of organic materials.
The methods and scheduling of reservoir clearing, grubbing,
and other site preparation techniques should be assessed for
resultant impacts on water and general environmental quality.
Access roads through the basin should be planned to follow
reservoir contours. This will minimize soil erosion and allow
piling and burning of brush in place rather than dragging it
toward the valley bottom.^3 Large depressions in the reservoir
drawdown area should be self-draining to avoid ponding and
stagnation of reservoir water. This means that channels or
ditches may have to be cut. Reservoir clearing should be sched-
uled for the dry season to minimize erosion of the unprotected
reservoir during heavy rains. Reservoir clearing should be
scheduled closely with work progress on the dam structure and
ideally should be completed just prior to reservoir filling so
that time of exposure is kept as short as possible. In addi-
tion to the increased threat of erosion, the regrowth of herba-
ceous cover in a long lag period between clearing and filling of
the reservoir can contribute a significant additional oxygen
demand in the first years of impoundment.54
Soil conditions in some parts of the reservoir may posfe
exceptional hazards to future water quality. Swamps, bogs, or
peaty soils with high organic contents are likely to impart
characteristics unacceptable from the public water supply stand-
point. Organic rich soils may be stripped and removed from the
reservoir, plowed under, or covered with a layer of mineral soil
to prevent leaching of excessive iron, manganese, color, and
other undesirable constituents. The decision whether to do any
of these things will be influenced by the amount of area exhi-
biting unfavorable soil conditions, the anticipated impairment
of water quality for proposed water uses, the cost of the treat-
ment, and the arrangements for water supply withdrawal and
reservoir discharge.
IV-56
-------
Selective Withdrawal Outlets
Dissolved oxygen and temperature are two principal water
quality criteria used to gauge the need for multilevel releases
at an impoundment project.55 Downstream requirements, uses of im-
pounded water, and physical features of the project are also of
concern in evaluating the applicability of selective withdrawal
to a particular reservoir. Multilevel intake structures have
been constructed at all types of single and multiple-purpose pro-
jects. A 1970 survey of 90 dams equipped with selective with-
drawal devices is summarized in Table IV-4 to indicate the pre-
vailing uses.
Table IV-4. Types of Impoundments Equipped
With Selective Withdrawal
Primary Purpose(s)
Number of Projects
Single-purpose flood control
20
Single-purpose water supply
21
Single-purpose power
2
Water supply and flood control
21
Water supply and low-flood augmentation
6
Flood control and power
4
Other (includes navigation, irrigation
16
and fish propagation in various combinations
with the above)
Source: "Register of Selective Withdrawal Works in the United
States," Task Committee on Outlet Works, Committee on Hydraulic
Structures, R.E. Nece, Chairman, Journal of the Hydraulics Division.
ASCE, Vol. 96, No. HY9, Proc. Paper 7533, September 1970, pp.
1841-1372.
Water supply is a primary impoundment purpose in 6 3 percent
of the projects surveyed. Assuring provision of high quality
water for municipal and industrial uses was an important factor
in the decision to utilize selective withdrawal facilities.
If the EIS has satisfactorily demonstrated the probability
of strong thermal stratification, eutrophication, and associated
water quality problems at a proposed impoundment, then adverse
downstream impacts from low-level discharges may occur. Multi-
level outlets should be considered as one mitigation alternative
worthy of investigation. Uses, advantages, and limitations of
selective withdrawal are discussed below.
-------
Withdrawal from Impoundment for Water Supply. The most
common use of selective withdrawal facilities is for control-
ling the temperature or chemical quality of water which is
withdrawn from an impoundment for municipal and industrial
water supply. Withdrawal points may vary from two intakes
(one near the surface and one deeper in the reservoir) to
numerous intakes which are evenly or unevenly spaced and are
capable of blending water from two or more elevations. Multi-
level intakes can provide some flexibility and control over the
quality of water introduced to a supply system. It should be
noted, however, that their inclusion in a project may simply be
a safety precaution in the event that quality problems are
encountered after construction. In any case, the design should
be based on thermal and hydraulic modelling studies and de-
tailed water quality studies. The most frequently noted water
quality problems that can sometimes be ameliorated by selectively
withdrawing water from an impoundment consist of:
e Tastes and Odors. Highly objectionable tastes and
odors may be imparted to hypolimnetic waters under
anaerobic or low dissolved oxygen conditions due to
decaying organic matter and high sulfide concentrations.
In eutrophic reservoirs, water from the euphotic zone
may also have some taste and odor from algae, thus
restricting the range of depths from which water of
suitable quality can be drawn during the stratified
period.56
© Iron and Manganese. Metallic salts of iron and man-
ganese are released from bottom sediments in a reducing
environment. They may reach concentrations at which
objectionable tastes and odors are detectable and the
staining of clothes occurs. Although they are prim-
arily "aesthetic" pollutants, criteria for acceptable
maximum levels of iron and manganese are included in
federal drinking water standards. Oxidation of excessive
iron and manganese during prechlorination of such hypo-
limnetic water produces undesirable color, which once
in a water system may persist for several weeks.56
Since a buildup of these compounds is normally confined
to the deeper, unoxygenated parts of a reservoir, with-
drawal from the epilimnion or thermocline may avoid
high concentrations of these ions.
0 Turbidity. Sediment laden density currents are fairly
common in larger reservoirs. Their course through a
reservoir is influenced by sediment concentrations,
inflowing current velocities, and temperature dif-
ferentials .57 High turbidity may contribute to
chlorine demand or interfere with water treatment
-------
processes such as coagulation and ion exchange. By
using outlets at different depths, water may be with-
drawn from above or below the undesirable layer.
© Salinity. Because of the extensive development of
irrigation projects and reuses of water, salinity
has become a major problem in the West. Variations
of dissolved solids with depth in a reservoir may be
pronounced which suggests that multilevel intakes
could be used to select water with acceptable dis-
solved solids concentraitons, if available. These
substances are not removed by conventional treatment
and may cause tastes at levels higher than the recom-
mended limits.
e Radioactivity and Toxic Substances. It has been sug-
gested that knowledge of seasonal stratification,
flow patterns, density currents, and other character-
istics may be useful in special circumstances for pro-
tecting the quality of water released from a dam or
withdrawn for public use.58 Accidental spills of
toxic or radioactive substances upstream from a strati-
fied reservoir are likely to be confined to a narrow
depth band as the inflow seeks its density level. In
the summer stratification period the pollutant may
enter as an overflow or interflow and remain confined
to a well defined layer. Use of multilevel withdrawal
in this instance could perhaps prevent or minimize in-
terruption of water supply service by safely drawing
water from another level. The situation could be compli-
cated by suspended matter absorbing harmful material and
settling to the bottom or deeper parts of the reservoir.
o Temperature. Although no specific temperature limits
exist for municipal water supplies in the United States,
there is a definite aesthetic benefit associated with
cool waters.59 Economic advantages may also be evident
if the impounded water supply is used for industrial
cooling. Because of overriding water quality consider-
ations mentioned previously, it is sometimes not feas-
ible to operate multilevel outlet works solely for
maintaining cold water in the supply and distribution
system. Withdrawal depth limitations imposed by taste
and odor, iron and manganese, or other constituents may
necessitate use of water with a higher than desirable
temperature. However, the flexibility of temperature
control may be critical in maintaining downstream condi-
tions favorable for other water uses.
IV-59
-------
Impoundment Releases for Downstream Quality Control. Water
quality problems caused by the development of thermal stratifi-
cation and consequent dissolved oxygen changes should be con-
sidered in the planning of any impoundment. Because an impound-
ment may have a useful operating life of one hundred years or
more, probable future stream uses must be analyzed in conjunction
with impoundment-induced water quality changes. Justification
for selective withdrawal or other mitigating project features may
not be evident on the basis of current conditions alone. Some
uses of selective withdrawal for controlling or influencing down-
stream water quality are:
© Regulation of Temperature. Distinct thermal gradients
in a stratified impoundment may permit fairly close con-
trol of discharge temperatures. Downstream water uses
may in some cases present mutually exclusive temperature
requirements. It is important that the various needs be
identified in the EIS. Use of the stream as a source of
cooling water for an electric power generating station or
industry would favor release of cold water, as would the
creation of a new, or maintenance of an existing coldwater
fishery. On the other hand, temperatures comparable to
those occurring without impoundment might be desirable
for irrigation water supplies, recreation, and preservation
of natural fish life. Since the thermal structure of a
stratified impoundment is very much interrelated with water
quality, temperature regulations for particular uses cannot
be separated from accompanying quality characteristics. A
deficiency of dissolved oxygen in water selectively dis-
charged from the hypolimnion may negate the benefits of
reduced temperatures for downstream fisheries. The water
may also be corrosive or contain concentrations of iron
or other substances detrimental to use for public water
supply.
o Maintenance of Assimilative Capacity. Release of water
containing adequate dissolved oxygen to meet stream standards
and waste load requirements may be accomplished by selec-
tively withdrawing from the epilimnion in the summer
months. Downstream temperatures are likely to be increased
by this mode of operation.
o Regulation of Physical and Chemical Quality. Any physical
or chemical constituents exhibiting vertical gradients, or
affected by inflow density currents, may be controlled to
some extent by use of multilevel outlets (several examples
were discussed previously in relation to water supply
withdrawals).
Design and Operational Considerations. If selective with-
drawal works are proposed as part of an impoundment project plan
the EIS should contain supporting information on their proposed
operation relative to water quality or temperature selection.
-------
Predictions of water quality changes, stream uses, and hydro-
graphic modifications are necessary to judge whether miticratina
measures for water quality control not considered in the F.IS
warrant attention and study.
An assessment of the need for selective withdrawal facili-
ties should include several considerations. Initially the de-
termination of existing and future needs and objectives for water
quality management should form the basis for design of selective
withdrawal facilities. Secondly, in order to meet specific
physical, chemical, and biological requirements of the releases,
there should be an evaluation of the effects of the size, shape,
spacing, and number of outlets.60 Finally, criteria indicating
when and how the facilities will be used and formulae for pre-
dicting withdrawal layer characteristics are essential for effec-
tive operation of multilevel outlet works.^
The Tennessee Valley Authority, the Bureau of Reclamation,
and the Corps of Engineers have all constructed project incor-
porating selective withdrawal facilities. Some hydroelectric
dams licensed by the Federal Power Commission also have multi-
level outlets. Knowledge of the hydraulic and water quality
behavior of reservoirs under various conditions has been gained
both from research and from observations and studies of existing
impoundments. Experience has shown that professional judgement or
extrapolation of results at one impoundment to another cannot
substitute for detailed, site-specific investigations and model-
ing. Prior to construction of Folsom Dam in California it was
concluded, based on experience at the existing Shasta and Friant
Dams, that multilevel power outlets would not be required for
maintaining suitable fall spawning temperatures for salmon in
the American River.56 The conclusion proved to be incorrect as
cold hypolimnetic water was frequently depleted before the fall
spawning period. If multilevel discharge facilities are included
in a project plan, or if potential water quality problems suggest
their inclusion, the reviewer should ascertain that accepted
prediction techniques are used (See Section IV.B.2) to provide
reasonable assurance that proposed objectives for water quality
control will be met.
Use of selective withdrawal may not completely solve the
anticipated water quality problems discussed earlier and may have
some detrimental effect on water quality. If nutrient loadings
in streams draining the area upstream from a proposed reservoir
site are relatively high then the situation typified by undesira-
ble aLgae growth in the epilimnion and oxygen deficiency in the
hypolimnion is likely to occur. At the Casitas Reservoir in
California, nine selectively level intakes with a vertical spacing
of 7.3 m (24 ft) have not afforded sufficent flexibility to
eliminate withdrawal of poor quality water for municipal supply.
Treatment with copper sulfate for algae control and destratifi-
IV-61
-------
cation by air injection have both been used to supplement selec-
tive withdrawal.56
The Corps of Engineers has sponsored a number of studies on
the effects of selective withdrawal on water quality and fisher-
ies, the results of which may aid in -identifying and assessing
potential impacts of different discharge regimes. Analysis of
data from more than 100 stratified impoundments indicate that
continuous discharges from the hypolimnion may increase dissolved
oxygen levels in the deeper parts of a reservoir^. The data
were reflective of late summer and fall conditions. This is a
period of intense stratification and usually results in the lowest
dissolved oxygen levels. These results suggest that the fishery
potential of a stratified impoundment may be enhanced if releases
of relatively poorer quality hypolimnetic water are made.
The above observations neglect possible downstream thermal
requirements and the impact of relatively poorer quality hypo-
limnetic discharges on waste assimilative capacity and other
water uses. Discharges from the hypolimnion or thermocline
region may induce water quality patterns in an impoundment that
are different from those resulting from release of surface waters.
The differences may be important in determining how to operate
selective withdrawal works for specific management purposes.
Turbine Aeration
In impoundment projects which provide hydroelectric power
generation facilities, turbine aeration offers a means to in-
crease dissolved oxygen concentrations of water drawn through
low-level power intakes. The simplest system introduces air
through draft tube vents that are built into many projects to
control vibration.63 Air flow is induced by negative static
pressures developed in the draft tube. The location of modern
turbines at or below the tailrace elevation may eliminate nega-
tive pressures or produce positive pressures in the draft tubes
necessitating an external power source to force air into the
water stream. This difficulty can be overcome by using wedge-
shaped deflector plates to create negative pressures and draw
air into the draft tube.64 Once air is introduced, turbulence
and increasing pressure enhance absorption of oxygen.
Capital costs for turbine aeration systems are relatively
small and operating costs consist mainly of reduction of gener-
ating efficiency. Turbine efficiency losses averaging less than
.1 percent to about 5 percent have been reported. Power gener-
ating efficiency losses during turbine aeration decrease with
increasing head and with increasing flow through the turbine.
Most studies conducted at existing projects have shown that
transfer efficiency falls off rapidly as the oxygen concentra-
tion in water passing through the turbines increases. The
T\7_ c r>
-------
technique of turbine aeration should not be relied on to in-
crease dissolved oxygen concentrations of anaerobic or poorly
aerated water more than about 2-3 mg/1 with higher initial
oxygen levels. Oxygen transfer may also be less efficient at
higher flows than at low flows.
The degree of aeration attainable by simple turbine venting
may be insufficient to meet minimum stream standards for dissolved
oxygen during summer and fall; the time period when oxygen deple-
tion in the hypolimnion is typically greatest.
A highly valued stream fishery might be adversely affected
by dissolved oxygen concentrations below 4 mg/1. The concen-
tration of 4 mg/1 is a floor value to protect sizeable popula-
tions of resistant species and successful passage of most
migrants. Higher concentrations may be needed in many cases
because production of sensitive species may be reduced at the
lower DO concentration. Location of a hydroelectric impoundment
on a freely flowing tributary stream may present conditions
that are conducive to rapid natural reaeration downstream with
no significant water uses intervening in the affected reach.
In this case, the need for high concentrations of dissolved
oxygen immediately downstream from the dam may not be as
critical. In assessing mitigating features for water quality
improvement, downstream water uses and water quality require-
ments should be examined and compared with expected water quality
of impoundment discharges.
Discharge Aeration Using Howell-Bunger Valves
The Tennessee Valley Authority has conducted extensive re-
search regarding the aeration efficiency of the Howell-Bunger
valve, which is a fixed dispersion cone valve. The valve has
been used at several TVA impoundments and has been shown to be
an effective aeration device. Aeration efficiencies, defined as
the ratio of the difference between the initial and final
oxygen deficits to the initial deficit, were found to be con-
sistently greater than 0.8 when outflow velocities exceeded
9 m/sec (30 ft/sec).65 initial dissolved oxygen concentrations
were not found to affect appreciably aeration efficiency.
It appears that Howell-Bunger valves could be used success-
fully for aeration at a wide variety of impoundment projects
where hypolimnetic discharges are expected to cause downstream
water quality problems. The valves may be situated to discharge
water horizontally into a containment structure or tunnel as
well as directly into the stream channel below a dam. Such
facilities could be provided at hydroelectric projects to aerate
the relatively small, off-peak discharges occurring at night and
on weekends.
IV-6 3
-------
Several possible advantages of utilizing Howell-Bunger
type valves for reservoir discharge aeration should be con-
sidered. In contrast to turbine aeration discussed above, a
properly designed cone valve aeration system is effective in
increasing dissolved oxygen to near-saturation values regardless
of initial concentrations. The valve could not be used during
a peak power generating cycle because of the magnitude of dis-
charges involved. It appears that the Howell-Bunger valve would
permit maintenance of both cooler temperatures and better oxyge-
nated conditions downstream from a stratified impoundment in the
summer and autumn. Whether the altered thermal regime is bene-
ficial would depend in large part on downstream water supply,
cooling, fisheries, recreation, and other uses and needs.
Destratification and Hypolimnetic Aeration
Various systems for mixing and aerating stratified reservoirs
have been devised although actual operating experience has been
restricted almost exclusively to impoundments with volumes of
less than 5 x 10® (40,500 acre ft). The basic purpose of
either destratification or hypolimnetic aeration is to elimi-
nate or avoid exygen depletion and associated water quality
changes in the deeper parts of an impoundment. Maintenance of
aerobic conditions inhibits the leaching of color, solutions of
iron, manganese, and nutrients from bottom sediments and the
production of hydrogen sulfide. All of these could be detri-
mental to various water uses.
Prediction or estimation of the concentrations of objec-
tionable substances that will occur in a new impoundment, as a
result of anaerobic conditions, cannot be done with any degree
of certainty using present modelling or quantitative techniques.
However, it is reasonable to assume that concentration levels
will probably exceed prescribed limits for raw water sources
if stable stratification and oxygen depletion are expected.
Under these conditions, artificial destratification can be used
to maintain dissolved oxygen throughout the reservoir and suppress
the solution or leaching of iron, manganese, color, and other
constituents. Other possible effects of destratification should
also be anticipated and assessed in view of overall water resource
needs. Destratification tends to increase the heat budget of an
impoundment considerably. The entire water body will become iso-
thermal and exhibit a temperature that may approach that of the
epilimnion under stratified conditions. The cold water reserve
of the hypolimnion may be needed for cooling purposes or for
regulation of stream temperatures below the dam during certain
periods. This situation might arise during migration and spawn-
ing of anadromous species that have definite thermal requirements.
Attempts to lower water temperatures and eliminate oxygen deficits
by artificial destratification, thereby creating suitable summer
IV-6 4
-------
trout habitat, have been unsuccessful. Desirable dissolved
oxygen levels can be maintained but minimum temperatures are in-
creased to intolerable levels.66
Table IV-3 and pertinent state water quality criteria should
be consulted for thermal requirements applicable to important
fish species which may be present in or downstream from a pro-
posed impoundment area. Protection of indigenous aquatic biota
or migratory species will define, in some cases, allowable thermal
alterations due to impoundment. Artificial destratification
reduces flexibility in downstream temperature control and may
lead to unacceptably high temperatures during critical spawning
or migration in the autumn. The evaluation of thermal require-
ments should be coordinated with the U.S. Fish and Wildlife
Service or the state fish and game agency if specific constraints
due to fisheries exist or if the EIS is deficient or unclear as
to possible effects.
Some of the advantages and disadvantages of artificial
destratification and hypolimnetic aeration are summarized in
"Measures for the Restoration and Enhancement of Quality of
Freshwater Lakes."66 Several case studies and cost estimates
are also presented. Although some detrimental effects have been
observed, these methods may improve the quality of raw water in
an impoundment, reduce treatment costs, and perhaps benefit the
reservoir fishery. Not enough is known about the ecological
impacts on reservoir productivity, algae, zooplankton, and fish
to permit a thorough assessment of their beneficial and detri-
mental effects. The need for reservoir aeration or mixing can
best be determined after a project becomes operational. Toetz
et a_1.6 7 have reviewed and analyzed a large portion of the
literature concerning biological impacts of artificial destrati-
fication and aeration. This publication should be consulted for
additional information on ecological effects.
IV-6 5
-------
IV.C. Review of Solid Waste Management Impacts
Activities during both the construction and operational
phases of an impoundment project may generate solid wastes
that require handling and disposal. The reviewer should in-
sure that short-term and long-term solid waste management
requirements have been identified and appropriately quanti-
fied in the EIS. Acceptable disposal methods should be em-
ployed to minimize potential adverse impacts.
IV.C.l. Sources of Impacts
Solid waste impacts may occur both in the short term
during construction of an impoundment and in the long term from
recreation-generated refuse and other waste sources. Among the
common components of solid waste that must be dealt with during
the construction phase are demolition materials such as con-
crete, brick, wallboard, plaster, and used lumber; packaging
materials including paper, cardboard, plastic, excelsior and
metal retaining bands; wood including trees and scrap products;
rubber; plastic; glass; pesticides; and pesticide containers.
During operational phases, flood debris and refuse from public
use areas represent the major sources of solid waste. A full
review of potential impacts includes consideration of the
storage, collection, transport, resource recovery, waste re-
duction, and ultimate disposal of waste materials.
Storage. Storage of solid waste at the construction site
is generally temporary. Provisions must be made for proper
handling to minimize impacts. Operations such as clearing
and grubbing, stripping of topsoil for future use, and ex-
cavation can generate a significant amount of material. Of
particular interest is stockpiled soil which could be trans-
ported to nearby streams by erosion processes. Stumps, timber,
and slash usually present no significant pollution problems,
although disposal may pose difficulties because of the massive
quantities involved.
Contractors often utilize temporary scrap depots for used
or leftover materials such as lumber, various pieces of fab-
ricated metals, large empty containers and other material. Ex
cept for empty containers which may have toxic residues, most
of this material is nonpolluting.
The impact of refuse generated from food, and food con-
tainers, merits special consideration when the construction
activities occur near inhabited areas. The major problem is
the potential attraction of rats, dogs, and cats to the site.
Covered waste containers strategically placed around the
construction site and emptied periodically tend to eliminate
these problems.
IV-66
-------
The long-term solutions for adverse storage impacts are
oriented toward reduction of litter, prevention of entry by
animals, and reduction of odors. Provisions for temporary
storage of recreation-generated refuse obviously must be made.
Although open top barrels are often used, it is preferable to
use enclosed containers with easy to open lids or doors. A
sufficient number of containers should be provided to accommo-
date peak loads and thus reduce littering. The Corps of En-
gineers requires a minimum of one trash receptacle for each
three to five picnic tables at the recreation areas.^8
Collection. The EIS should identify waste collection
methods and the frequency of collection, where applicable,
both during construction and after the impoundment has been
completed. The latter would apply to recreational areas,
visitor centers, and routine collection of floating debris
at outlet structures and log booms. For garbage and other
solid waste generated at recreational sites, collection at
least twice a week is desirable to minimize problems with
flies and odors.
Transport. Transport of solid waste from the construc-
tion site to the ultimate disposal area may cause dust and
noise problems and contribute to the damage to local roads.
Narrow roads with gravel shoulders are most susceptible to
pavement edge-breaking, especially during periods of alternate
freezing and thawing. Covering all loaded materials before
traveling off-site may be required by State or local regula-
tions. Mud and dust problems from construction vehicles
traveling on public ways may be particularly important if the
site is near an urbanized area.
Resource Recovery and Waste Reduction. Waste recovery is
especially important where materials are proposed to be dis-
posed of in a local disposal facility. Reduction of waste
volume at the construction site will be beneficial, and may be
necessary, if available local landfills would be severely im-
pacted by the added load of construction debris. This reduc-
tion in volume would also reduce the vehicle hours travelled
on municipal roads. The reuse of "waste" materials, such as
wood mulch from timber and slash, should be encouraged. The
mulch, for example, could be used as a substitute for netting
in stabilizing slopes and for prevention of erosion. Removal
of all marketable timber from areas to be cleared would reduce
disposal problems. Since the quantities of spoil material may
be significant, its use as fill in borrow areas should also be
considered.
IV-67
-------
The EIS should address the issue of clearing, which may
affect the amount of waste produced and the overall impact
of solid waste operations. A balance between clearing to
facilitate construction operations and preservation of vegeta-
tion should be reached, especially if there are species unique
to the area. Plans should delineate the types and extent of
various species before construction and should also show what
would be removed and/or replaced after construction. Other
effective steps to reduce the amount of waste generated should
also be considered, particularly during construction.
Ultimate Disposal. Ultimate disposal of construction-
generated refuse is the key element in the review of solid
waste management operations. For the most part local and
State regulations will apply to disposal of such waste. In
the absence of either local or State regulations, or if dis-
posal sites are on Federal land, the "Thermal Processing and
Land Disposal of Solid Waste"69 guidelines should be followed.
Disposal of stumps, timber and slash from clearing and
grubbing operations generally represents the largest source
of solid waste at an important construction site. Proposed
disposal areas and methods should be clearly delineated in the
EIS, particularly if a disposal site outside of the impound-
ment area is required. Unsalvageable demolition debris gene-
rated by removing or relocating structures from the flood
pool area may in some instances add significantly to waste
volumes requiring disposal.
On-site disposal practices typically consist of some form
of land disposal method such as burying the material in an
abandoned borrow area, which is then inundated, or by open
burning. On-site disposal methods should be questioned if they
involve disposal of empty chemical containers from paints,
solvents, pesticides and herbicides; acids for cleaning masonry
and asphalt; or other potentially hazardous materials. Many of
these containers leave residues which are nonbiodegradable and
can remain chemically active for many years. The disposal of
unused pesticides and pesticide containers should be done in
accordance with EPA1s proposed rules, "Pesticides and Containers;
Acceptance, Disposal, and Storage."70 The environmental impact
statement should include a provision that garbage and other non-
inert materials will not be disposed of in "inert" waste disposal
areas.
A long-term consideration is the disposal of debris which
accumulates in and around the impoundment area. This problem
may be particularly acute at flood storage reservoirs follow-
ing pool drawdown. The material brought down by floodwaters
consists mostly of fallen timber and brush which remains in
IV-6 8
-------
the drawdown zone or is conveyed to the dam or trashracks pro-
tecting the outlet works. Left to rot, the dried timber may
present a serious fire hazard. The EIS for a flood control
impoundment should address this problem and indicate how dis-
posal of the debris is to be accomplished, particularly if
larger quantities are involved.
IV.C.2 Review of Impact Quantification
It is quite difficult, if not impossible, to determine
accurately the quantities of construction refuse since site
characteristics and the extent of reuse of materials vary con-
siderably, particularly such things as forming materials, timber,
slash and other spoil material. However, a general schedule of
expected waste generation, including recovered materials,
could serve an important function if local community disposal
sites are to be used. If peak waste generation periods such
as produced from clearing, grubbing, and final clean-up opera-
tions coincided with peak tourist inflow in a particular
community, transporting the solid waste to the local disposal
facility might increase traffic congestion or result in tempo-
rary economic decline from a reduced number of tourists. For
on-site disposal this schedule becomes less important.
Reasonable estimates of waste quantities generated from
recreational areas or visitor centers can be made based on
projected visitation figures and the number of various types
of facilities. It is important that potential recreational
development by private interests as well as the federal govern-
ment be described in the EIS. Table IV-5 may be used to
estimate waste quantities if projections of initial and
future recreational development are available.
It is not uncommon for recreational facilities at even
fairly small impoundments, with water surface areas of less
than 1000 acres or so, to attract several hundred thousand
visitors in a season. At larger projects, annual visitation
may run in the millions. Using a waste generation rate from
Table IV-5 of 0.93 lb/picnicker day (0.423 kg/picnicker day)and
hypothetical annual total of 400,000 picnickers, 186 tons
(173 metric tons) of waste would require disposal. Also,
most of the refuse would be generated in the 3 or 4 warmer
months. This waste load increment would not significantly
affect a large sanitary landfill operation. However, a rural
landfill serving 2000 people may process 4 or 5 tons per day of
refuse. In this case, the addition of an average 1.5 to 2 tons
per day during the recreation season may put a substantial burden
on the operation and available landfill space.
The quantities of the debris resulting from flood control
operations are difficult to estimate. Although no specific
-------
Table IV-5. Waste Generation Rates for Recreation Sites
Recreation Site
Average rate of waste generation
(90 percent confidence interval)
Campground
1.2 ± 0.08 lb/camper day
Family picnicground
0.93 i 0.16 lb/picnicker
Group picnicground
1.16 + 0.26 lb/picnicker
Organization camp
1.81 ± 0.39 lb/occupant day
Resort area
Rented cabin
1.46 t 0.31 lb/occupant day
Lodge room (wo/kitchen)
0.59 ± 0.59 lb/occupant day
Restaurant
0.71 t 0.40 lb/meal served
Residence
2.13 t 0.54 lb/occupant day
Observation site
0.05 i 0.03 lb/incoming axle
Visitor center
0.02 t 0.008 lb/visitor
Swiriming beach
0.04 t 0.01 lb/swimmer
Concession stand
0.14 lb/patron
Source: Little, H.R., "Design Criteria for Solid Waste Management in
Recreational Areas," U.S. Environmental Protection Agency, Solid Waste
Management Series Report (SW-91ts), 1972, p. 7.
techniques exist to assess the "magnitude of this debris problem,
experience at other impoundment projects in the region may give
some insight into the quantities of floating material to ex-
pect .
IV.C.3. Assessment of Impacts
The major element in assessing the impact of recreational
and other solid waste is the relationship between anticipated
waste quantities and the capacity of the selected disposal
areas. Initial estimates can be made to determine the signifi-
cance of solid waste from recreational areas as described in
the preceding section. The development of a landfill to serve
v-"7 n
-------
recreational areas at an impoundment would not, in most cases,
require a significant amount of land. However, site character-
istics would need to be suitable for avoiding or minimizing
potential pollution problems. Generally, the guidance on de-
sign and operational criteria for recreational landfills con-
tained in "Design Criteria for Solid Waste Management in
Recreational Areas,"71 should be followed. To aid in this
assessment a summary of impoundment-related solid waste im-
pacts is given in Table IV-6.
Disposal of construction waste should not pose any pollu-
tion hazards if acceptable sites and methods are set forth
adequately in construction specifications for the project.
Much of the construction debris may normally be buried in
excavation or borrow areas or in the lower reservoir that will
be flooded. This will create few solid waste problems for
nearby disposal sites. Where the proposed conservation pool is
small and shallow, debris disposal at the bottom of the reservoir
may not be feasible or desirable. An off-site landfill may be
required to receive construction waste, particularly stumps,
cleared trees, and brush. If no discussion of construction
waste disposal appears in the EIS, and the amount of clearing
or other operations suggest the generation of potentially large
quantities of solid waste, then clarification of these points
should be requested.
Estimation and assessment of the effects of open burning
of solid waste are discussed in the section on air impacts.
Open burning should be discouraged unless it has been demon-
strated that no feasible disposal alternatives exist. Due
caution must be taken to avoid burning smoke-producing materials
such as rubber and plastics or containers with potentially toxic
residues. Favorable meteorological conditions should also
prevail.
IV-71
-------
Table IV-6. Summary of Solid Waste Impacts
H
<
i
Material
Source
Characteristics
Significance
Mltlgatlve Measures
Steps, tlsfcer
and slash
Clearing and grubbing
Basically nonpollutlng
Economic Inpact on local coeaunlty If Its disposal
site Is used. Generally largest source of solid
aaste. Clearing night result 1n a potential source
of erosion and sedlnent transport to streas. If
burned on-site, refer to air Inpact.
Cut and clear selectively; sell
aarketable t1c*er, reuse on-site
as oulch.
Rock
Blasting, excavation
of dea foundation,
splllMiy channel, etc.
Basically nonpollutlng
If a borroa area 1s used, night result In pernanent
scar on landscape unless provisions are oade for
restoration. Volune nay be significant.
Use as rip-rap 1n core of dsns or
road foundations
Masonry oasts
Concrete dtsa or
appurtenant structure!
Nonpollutlng when
hardened
Bust avoid disposal of wet concrete near bodies of
water to prevent slltatlon.
Use as fill In borrow areas.
Excoil building
8 scrap
neterials
Fonrlng activities 1
supplies
Mostly nonpollutlng
Litter problen at construction site; partially full
containers with toxic Materials (solvents, pesti-
cides, acids) might be discarded and cause potential
pollution problem due to high -ocallzed concentra-
tions. Might be burned at construction site.
Reuse 1n future projects, estlnate
saterlal quantities accurately, dis-
pose of empty containers properly,
use partially full containers at
other Jobs.
Food products
1 containers
Recreational 1 visitor
canters 1 construction
corkers
Polluting potential,
malodorous
Might create litter and odor problens, and attract
anlnals. Might be burned at construction site.
Provide sufficient nusber of con-
tainers, collect frequently, and
dispose of 1n a landfill or other
acceptable manner.
Construction vehicles
on public roads trans-
porting solid waste to
local disposal facility
Creates broken paveaent, noise, cud on street, dust,
and adds to traffic congestion.
Select alternative routes, reduce
loads, keep vehicles clean and In
good repair. Schedule deliveries
to alleviate any potential traffic
problem.
~
Excavation of Impound-
ment area
Potentially pollut-
ing
Stockpiled soil materials might be a source of sedl-
nent to streams.
Place waste material In borrow and
fill areas as soon as practicable;
grade and seed or apply oilch.
Otter spoil
tutorial
Debris at log boons,
outlet structures;
debris from flood
mters
Generally non-
polluting
Volmay be significant, especially at flood
control reservoirs. Potential killing of trees
and other vegetation by submergence; unsightly and
harmful mud deposits.
Practice good upstreao forestry
management; maintain disposal area
for this material, adjacent to site
(such as borrow area), to reduce
Inpact on local coomunlty.
-------
IV.D. Review of Air Impacts
In most cases the effects of impoundments on air quality
will be less important in comparison with impacts on water
quality, water resources, ecology, and land use. Except un-
der special circumstances of proximity to densely populated
areas, generation of significant traffic volumes, or probable
secondary development, an analysis of air quality impacts will
probably not be carried out in any detail in an impoundment
EIS, nor would it be required. To ensure that potential air
pollution problems are not overlooked, however, guidance is
presented for the identification of situations where primary
and secondary air impacts may be significant and a determination
of the adequacy of air quality analysis in the EIS should be
made.
IV.D.I. Sources of Impacts
The primary air quality impacts associated with impound-
ment development occur as a result of construction stage
activities. Construction related air pollution sources are
best illustrated by association with the pollutants they pro-
duce. These pollutants include:
Dust. One of the noticeable types of air pollution at a
construction site is particulate matter such as dust and
smoke. The types of construction activities which might produce
noticeable amounts of particulate include clearing and grubbing,
excavation, blasting, drilling, sand blasting and grinding, gunite
operations, concrete production, aggregate production and spread-
ing, stockpiling of materials, application of lime and fertili-
zers, pesticides and herbicides, and dust generated by movement
of equipment over the construction site.
Combustion By-Products. Another source of particulate
matter, as well as other air contaminants, is open or incinerator
burning of wood and other combustible wastes from clearing and
grubbing operations. Such burning should be permitted only when
no justifiable alternative is available. The relatively low
burning temperatures associated with open burning usually result
in the emission of particulates, carbon monoxide, and hydro-
carbons although the low temperature tends to suppress the
emission of oxides of nitrogen. Since the sulfur content of the
debris from clearing and grubbing operations is negligible, the
resultant emission of sulfur oxides is also negligible. Avail-
able emission factors for the burning of wood may be found in
"Compilation of Air Pollutant Emission Factors."72
Vehicular Emissions. Heavy-duty, diesel-powered vehicles
are the primary contributors of construction stage vehicular
emissions. Diesel vehicles emit pollutants from the same sources
IV-73
-------
as gasoline-powered vehicles and have the same general charac-
teristics as auto exhausts. Concentrations of some of the
pollutants, however, may vary considerably.
® Sulfur Dioxide. Emissions of sulfur dioxide are a direct
function of the fuel composition. Because of the higher
average sulfur content of diesel fuel (0.20 percent S)
as compared with gasoline (0.035 percent S), Sulfur
dioxide emissions are relatively higher from diesel
exhausts.
o Carbon Monoxide and Hydrocarbons. Because diesel engines
allow more complete combustion and use less volatile fuels
than spark-ignited engines, their hydrocarbon and carbon
monoxide emissions are relatively low. The hydrocarbons
in diesel exhaust are largely unburned diesel fuel.
© Nitrogen Dioxide. Both the high temperatures and the
large excesses of oxygen involved in diesel combustion
result in relatively high nitrogen oxide emission.
® Particulates. Particulates from diesel exhaust are in two
major forms, black smoke and white smoke. White smoke is
emitted when the fuel droplets are kept cool in an envi-
ronment abundant in oxygen as in cold starts. Black
smoke is emitted when the fuel droplets are subjected to
high temperatures in an environment lacking in oxygen as
in road conditions. A hot diesel engine properly ad-
justed and operated under design loads should emit no
visible smoke.72
Emission factors for heavy-duty, diesel-powered vehicles
typical of those used at large construction sites are also
presented in the publication "Compilation of Air Pollutant
Emission Factors."72
Secondary air pollution sources associated with impound-
ment development include, when applicable, highway develop-
ment or modification, parking facility development, and recrea-
tional area development such as camping facilities where open
fires might be permitted. Induced development of flood plains
below an impoundment due to increased flood protection is
another possible source of air pollution.
IV.D.2. Review of Impact Quantification
Unless any of the secondary air pollution sources listed
are present and apparently significant, only construction stage
impacts will warrant evaluation. Even then, unless the reviewer
can pinpoint that a major possible impact is evident, no de-
tailed critical evaluation is required.
IV-7 4
-------
Should a possible impact be identified, the impact potential
should be quantified in terms of the percentage of generated pol-
lutants which would reach the sensitive receptor under the most
adverse possible meteorological conditions. The probability of
the occurrence of worst case meteorlogical conditions, construc-
tion timing, and geographical influences must be carefully con-
sidered along with background ambient air quality levels. Meteor-
ological data should contain a one-year historical record if mod-
eling is to be employed. These inputs combined with an approxi-
mation of the magnitude of the project emissions should provide
sufficient background for the evaluation of sensitive receptor
impact and the need for abatement. For comparative purposes the
pertinent National Primary and Secondary Air Quality Standards
are listed in Table IV-7. Air quality standards and applicable
state implementation plan strategies are specific requirements
that must be addressed in any EIS on impoundment projects.
IV.D.3. Assessment of Impacts
The air quality assessment must first identify the primary
and secondary air pollution generators associated with the
impoundment project. The time span and magnitude of these
pollutant generators must also be addressed.
Air pollution sensitive receptors should be identified. Ex-
isting ambient air quality and the air quality influence of area
meteorological and geographical conditions should be addressed
to the extent applicable.
In many cases no significant air pollution problems will
arise. Reasonable care should be taken to see that any pos-
sible significant impact is identified, its magnitude estimated
and related to existing standards, and that abatement plans, if
necessary, are formulated.
For the limited secondary impact of existing highway modi-
fication which does not increase capacity, no air quality analy-
sis, either microscale or mesoscale, will be required for rural
areas.73
IV-7 5
-------
In the case of the associated secondary impact of parking
facility development, outside of standard metropolitan statisti-
cal areas, as defined by the U.S. Office of Management and Bud-
get, no new parking facility nor other new indirect source with
an associated parking capacity of less than 2000 cars, nor any
modified parking facility, nor any modification of an associated
parking area which increases parking capacity by less than 1000
cars requires an "indirect source" environmental analysis of air
quality impact.^ The EPA's "Interim Guidelines for Review of
the Impact of Indirect Sources on Ambient Air Quality," published
July 1974, may prove useful for evaluating parking facilities,
amusement parks, and recreational areas.
The referenced publications may be of assistance should any
question exist as to the significance or impact of any other
identified secondary source.
IV-77
-------
IV.E. Review of Noise Impacts
In the context of the overall environmental impact of an
impoundment project, noise pollution is not ordinarily con-
sidered a major impact category. Depending on the location,
size, and uses of an impoundment, noise impacts may be signifi-
cant enough to warrant analysis in the EIS, at least in qual-
itative terms. The guidelines of this section are intended
to assist in identifying probable noise impacts, estimating
their significance, and determining the adequacy of noise im-
pact assessment in an impoundment EIS.
IV.E.l. Sources of Impacts
As an environmental pollutant, noise may be defined as any
sound, independent of loudness, that may produce an undesired
physiological or psychological effect in an individual to the
degree that it may interfere with the social ends of the indi-
vidual or group. It is important to note that, unlike other
forms of pollution, noise has a rapid decay time. That is,
when the source of the noise is turned off, the noise dissipates
within a matter of seconds and further degradation of the en-
vironment ceases immediately.
The impact of noise is primarily dependent upon the charac-
teristics of the sound such as the sound pressure level or loud-
ness, its frequency, pattern and duration, the proximity of the
receiver, and the existing ambient level of background noise.
The primary and secondary noise generators for an impound-
ment project will consist of some combination of the following:
o> The primary construction noise generated on-site and
during on-road hauling operations.
9 Facilities constructed as part of the impoundment
development (i.e., power generating stations)
» Recreational facilities created as part of the im-
poundment development (i.e., lakes for power boating,
trails for motorcycling and snowmobiling, and parking
lots adjacent to sensitive facilities).
© Highways and rail lines developed, relocated or
expanded as part of the impoundment/development
IV.E.2. Review of Impact Quantification
Few EIS|s on projects involving impoundments will be en-
countered which contain detailed analyses of noise impacts.
IV-7 8
-------
There are several reasons for this, including: (1) construc-
tion noise impacts are of relatively short-term consequence,
lasting, at most, over a construction period of up to several
years, (2) impoundments located in remote areas have no sensi-
tive receptors nearby, and (3) noise sources associated with
impoundment operation and use such as power generating facili-
ties, off-road vehicles, motorboats, and others are generally
overlooked or dismissed as insignificant. Since these noise
impacts can be important, they should either be evaluated in
the EIS or supporting information should be given to justify
a conclusion that the impacts are not significant.
The reviewer should be familiar with the following EPA pub-
lications for further background material on the description
and evaluation of noise:
o "Noise Facts Digest," prepared by Informatics, Inc.,
June 1972
® "Fundamentals of Noise Measurement, Rating Schemes
and Standards," NTID300.15
e "Effects of Noise on People," NTID300.7
© "Information on Levels of Environmental Noise Requi-
site to Protect Public Health and Welfare with an
Adequate Margin of Safety," March 1974 (550/9-74-004)
If special expertise is needed, the Office of Noise Abate-
ment and Control should be contacted.
In most cases the greatest impoundment-associated noise im-
pacts will occur during the construction phase. As a first
estimate, Tables IV-8 and IV-9 may be used to determine the noise
levels generated during various types of construction.
Since the actual noise levels decrease as distance from
the site increases, the noise levels established in Tables IV-8
and IV-9 must be adjusted for each receptor under consideration.
Table IV-10 may be used to obtain the specific reduction value
required.
In addition to the distance reduction, a natural barrier
such as a dense growth of trees extending at least 15 feet
above any line of sight between the source of noise and ex-
tending 100 feet (30.5m) deep can provide an attentuation of
approximately 5 dBA. An additional woods depth of 100 feet
(30.5m) may provide an additional 5 dBA attenuation, but the
total attenuation from vegetation should not exceed 10 dBA.
IV-79
-------
Table IV-8. Typical Ranges of Noise Levels at Construction
Sites with a 50 dBA Ambient Typical of Suburban
Residential Areas*
I
II
Units
Ground Clearing
84
84
Energy Average dBA
Excavation
88
78
Energy Average dBA
Foundations
88
88
Energy Average dBA
Erection
79
78
Energy Average dBA
Fini shing
84
84
Energy Average dBA
*Noisiest piece of equipment at 50 feet, other equipment at 200 feet
from observer.
I - All pertinent equipment present at site
II - Minimum required equipment present at site
Source: Bolt, Beranek and Newman, Inc., "Noise from Construction
Equipment and Operations, Building Equipment and Home Appliances,"
U.S. Environmental Protection Agency, December 31, 1971, p. 19.
Table IV-9. Typical Ranges of Noise Levels at Construction
Sites with a 70 dBA Ambient Typical of Urban Areas*
I
II
Units
Ground Clearing
84
84
Energy Average dBA
Excavation
89
79
Energy Average dBA
Foundations
88
88
Energy Average dBA
Erection
79
79
Energy Average dBA
Finishing
84
84
Energy Average dBA
*Noisiest piece of equipment, at 50 feet, other equipment at 200 feet
from observer.
I - All pertinent equipment present at site
II - Minimum required equipment present at site
Source: Bolt, Beranek and Newman, Inc., "Noise from Construction
Equipment and Operations, Building Equipment, and Home Appliances,"
U.S. Environmental Protection Agency, December 31, 1971, p. 20.
IV- 80
-------
Table IV-10. Reduction of a-Scale Sound Level at Various Distances
from a Vehicular Point Source, Relative to 50-ft.
Distance
Distance
Reduction
(ft)
On)
(dBA)
50
15.3
0
100
30.5
6
150
45.8
9.5
200
61
12
500
153
20
750
230
23.5
1000
305
26
2010
613
33.5
3140
957
40
Source: Anderson, G.S., L.N. Miller, and J.R. Shadley, Fundamentals
and Abatement of Highway Traffic Noise, prepared for the Federal High-
way Administration, June, 1973, p. 1-32.
Any receptor noise levels estimated from the preceding tables
must be considered in terms of a specified noise level which
is either on or off as a function of time. If this noise level
is projected over a period of time, and the normal background
sound level at the receptor is available, the expected receptor
noise impact may be converted to impact levels for comparison with
those in Table IV-11 (page IV-85) through the following operations:
Let L]-, = the background noise. This level may be con-
sidered as the equivalent sound level (Leg) exist-
ing before the introduction of the new noise, pro-
vided that its fluctuation with time is small
relative to the maximum value of the new noise level.
IV- 81
-------
T = TRACTION OF TIME L " ON
max
Figure IV-3. for Intermittent Lmax to Lb
SOURCE U S EPA, OFFICE OF NOISE ABATEMENT AND CONTROL. ' INFORMATION ON LEVELS OF ENVIRONMENTAL NOISE
REQUISITE TO PROTECT PUBLIC HEALTH AND WELFARE WITH AN ADEQUATE MARGIN OF SAFETY " WASHINGTON 0 C ,
MARCH 1974 P A 8
Let LMAX~ the established level of continuous construction
noise reaching the receptor.
= the fraction of the total time for during
which lmax is Present-
Let Y
Let L = L - L
MAX b'
the newI1LtheaI[d1JhPN' ^ the decibel difference between
k2 ? ^ . he Previously existing noise level (Lw) mav
"wors^case estimate?"6"06 t0 Fl9Ure IV'3' ThiS glveS a r°u9h
IV-82
-------
It is most important that the significance of the predicted
Leq noise impacts be weighted by the total time span, the length
of the construction stage, over which they will be experienced
as well as by the sensitivity of the receptor at the time of day
during which impacts will actually occur.
IV.E.3. Assessment of Impacts
Although noise can be a subjective experience in that the
same sound might be objectionable to one observer but not to
another, the following direct and indirect effects on humans
have been well documented.
Hearing Damage Risk. Potential hearing impairment, which
is a direct effect of noise, is of prime importance. Hearing
impairment may be classified as temporary or permanent. Tem-
porary hearing impairment may result from exposure to high
impulse noise such as from blasting or impact equipment. Re-
peated exposure to such noise or continuous high level noise
above 90 dBA can produce permanent hearing damage. Except
under unusual conditions, hearing damage risk to persons off the
the impoundment construction site is almost nonexistent.
Communication. Another direct effect of noise is its po-
tential interference with normal speech conversation and teach-
ing, telephone communication, listening to television and radio
broadcasts, and listening to music.
Relaxation and Sleep Interference. Noise affects sleeping
habits in two ways. It may lengthen the time taken to fall
asleep and it may interrupt sleep stages leading to awakening.
Other Effects. Physiological and psychological stress, an-
noyance, and task interference are for the most part dependent
on the particular individual and it is therefore difficult to
establish criteria. Physiological stress may include increase
in blood pressure and heart beat rate, such as from a sudden,
high level sound like blasting. Noise may also be a contribut-
ing factor to headaches, indigestion, ulcers, heartburn, and
gastro-intestinal complications. Noise generated from impact
equipment such as from pile drivers, jack hammers, and rock
drills is a likely source for most physiological stress. This
equipment might also be responsible for so-called psychological
effects including increased irritiability and nervous tensions.
The type of noise is particularly important in determining the
effect on individuals in this category of effects. High fre-
quency sound also tend to be more disturbing than low frequency
at the same level.
The masking effect of noise may also present a serious
hazard if auditory caution signals are masked such as railroad
crossings and back-up alarms on construction vehicles.
IV-83
-------
The effects of noise on wildlife are varied and the reviewer
should consult the publication "Effects of Noise on Wildlife and
Other Animals."75 This may be particularly important if en-
dangered species are involved.
Further information on the determination of the effects of
noise may be obtained from "Information on Levels of Environ-
mental Noise Requisite to Protect Public Health and Welfare
with an Adequate Margin of Safety."76 This document presents
information on noise levels based on current analyses, extrapo-
lations, and evaluations of the present state of scientific
knowledge. The informational levels provided in this report
are listed in Table IV-11. These noise level values are given
in Leq (24) and L<3n. Leq (24) is an equivalent A-weighted
sound level over 24 hours. Ldn is an Leq (24) sound level
with a 10 decibel penalty applied to nighttime levels. The
levels provided should not be construed as standards, nor
should they be thought of as discrete numbers, since they are
described as energy equivalents prepresenting noise levels based
upon cumulative exposure over a period of time. It must be kept
in mind that the data upon which the information statistics in
Table IV-11 are based is not "short run" or single event noises.
In summary, each of the following areas must be assessed to
a degree sufficient to fully explore all short-term and long-
term probable noise impacts associated with the project under
review.
o Sufficient background and technical information in
the introduction to the topic of noise
@ Adequate identification of existing noise levels,
probable sources of impacts, and probable impacts,
both direct and indirect
e A discussion of applicable noise control regulations
including:
(1) Existing noise ordinances
(2) Construction contract specifications concerning
noise
(3) Responsibility for contract specification
enforcement
(4) Possible noise abatement strategies, if nec-
essary. See "Noise Source Abatement Technology
and Cost Analysis Including Retrofitting."77
IV-84
-------
Table IV-11. Yearly Average* Equivalent Sound Levels Identified as Requisite
to Protect the Public Health and Welfare with an Adequate
Margin of Safety
Measure
Indoor
To Protect
Activity Hearing Loss Against
Inter- Considera- Both Ef-
ference tion fects (b)
Ou tdoor
Activity Hearing Loss
Inter- Considera-
ference tion
To Protect
Against
Both Ef-
fects (b)
Residential with
Outside Space
and Farm
Residences
Ldn
Leq(24)
45
70
45
55
70
55
Residential with
No Outside
Space
Ldn
Leq(24)
45
70
45
Commerci al
Leq(24)
(a)
70
70(c)
(a)
70
70(c)
Inside Trans-
portation
Leq(24)
(a)
©
70
(a)
Industrial
Leq(24)
(a)
70
70(c)
(a)
70
70(c)
Hospltals
Ldn
Leq(24)
45
70
45
55
70
55
Educational
Leq(24)
Leq(24)(
45
d)
70
45
55
70
55
Recreational
Areas
Leq(24)
(a)
70
70(c)
(a)
70
70(c)
Farm Land
and General
Unpopulated
Land
Leq(24)
(a)
70
70(c)
Code:
a. Since different types of activities appear to be associated with different levels,
identification of a maximum level for activity interference may be difficult except
in those circumstances where-speech communication is a critical activity. See Fig-
ure D-2 for noise levels as a function of distance which allow satisfactory com-
munication.
b. Based on lowest level.
c. Based.only on hearing loss
d. An Leq(8) of 75 dB may be identified in these situations so long as the exposure over
the remaining 16 hours per day is low enough to result in a negligible contribution to
the 24-hour average, i.e., no greater than an Leq of. 60 dB.
Note: Explanation of identified level for hearing loss: The exposure period which results
in hearing loss at the identified level is a period of 40 years.
~Refers to energy rather than arithmetic averages.
Source: U.S. EPA, "Information on Levels of Noise Requisite to Protect Public Health and Wel-
fare with an Adequate Margin of Safety," Washington, D.C., March 1974, p. 29 (EPA 550/9-74-004).
IV-85
-------
APPENDIX
FEDERAL AGENCY PROCEDURES RELATED TO
ENVIRONMENTAL ASSESSMENT OF IMPOUNDMENT PROJECTS
Page
U.S. Army Corps of Engineers A-2
Soil Conservation Service A-5
Bureau of Reclamation A-7
Tennessee Valley Authority A-9
Federal Power Commission A-ll
Water Resources Council and River Basin Commissions A-12
Fish and Wildlife Service A-14
A-1
-------
U.S. ARMY CORPS OF ENGINEERS78"80
The U.S. Army Corps of Engineers acts as an engineer consult-
ant to Congress and develops most of its water resources projects
by specific Congressional authorization. When local interests
feel the need for a flood control project they petition their
representatives in Congress. The Senator or Representative then
requests the appropriate Congressional committee to direct the
Corps to make a survey and furnish necessary recommendations.
The authority for a study is either a resolution adopted by
appropriate Senate or House Committees or a Congressional Act.
Some studies may be confined to a small area and have a compar-
atively simple solution. Other studies may cover an entire river
basin and require consideration of, among other things, naviga-
tion, flood control, erosion control, hurricane protection, water
supply, water quality control, hydroelectric power, drainage,
irrigation, and recreation.
When Congress makes funds available for construction, the
Corps prepares plans and specifications, awards contracts, and
supervises construction. The completed projects may be operated
and maintained by the Corps, or they may be transferred to another
agency or to local interests to operate and maintain. For pro-
jects with limited scope, Congress has authorized the Secretary
of the Army and the Chief of Engineers to approve these projects.
Projects of limited scope include small river and harbor im-
provements for navigation, small flood control projects, shore
and beach restoration, emergency bank protection, channelization,
flood repair, removal of wrecked vessels, and dissemination of
information to states and local communities. Generally, for
projects in which federal financing is more than $1,000,000,
Congressional approval for investigation and installation is re-
quired; whereas, projects in which federal financing is less than
$1,000,000 may receive Corps approval.
The projects receiving Congressional approval are different
in nature and scope from projects receiving Corps approval.
As such, the Corps has elected to employ two separate planning
processes.
A. Congressionally Approved Projects
The planning process for congressionally approved projects
consists of the following six steps:
(1) Project Investigation. During this step an inventory of
environmental resources is made, and the District Engineer (DE)
prepares a summary of environmental considerations. A determin-
ation is made on whether further investigation and expenditure
of funds for a more comprehensive and detailed survey are
A-2
-------
warranted. Public participation in the form of public meet-
ings is initiated and is used to develop a dialogue to assist
in the formulation of the project and the identification of en-
vironmental concerns. Also at this time, coordination with
federal, state, and local agencies is begun. Where necessary,
assistance from these agencies may be requested.
(2) Public Hearings. This activity provides a means for the
DE to make recommendations for improvements. Through a series
of public meetings, in which alternatives for improvements
are discussed, the DE is able to refine his determination of
the proper scale and scope of improvements, the economic just-
ification, and the equitable sharing of costs and responsibili-
ties by federal and nonfederal interests. These findings make
up the Survey Report which is completed at this time. Also
completed at this time is the Preliminary Draft EIS. The DE
circulates the Survey Report and the Preliminary Draft EIS to
concerned federal, state, and local agencies, citizen groups
and individuals on the project mailing list for review and
comment. Utilizing the comments received, the DE revises the
above reports which then serve as a basis for the DE to make
recommendations for improvement.
(3) Corps Recommendations. The Survey Report and the Draft
EIS are reviewed by the Division Engineer, the Office of the
Chief of Engineers (OCE), and the Board of Engineers for Rivers
and Harbors (BERH). Based upon this review, OCE and BERH make
proposed recommendations.
(4) Formal Review and Comment. OCE completes the Draft EIS.
The Survey Report and the Draft EIS are then circulated for
review and comment to local, state, and federal agencies at
the Washington level in accordance with established procedures.
The Draft EIS and other reports are furnished to the Council on
Environmental Quality (CEQ) at this time.
Based on the comments received, BERH may revise its recom-
mendations, the DE prepares the Final EIS, and OCE prepares its
final report on the proposed project.
(5) Transmittal of EIS. The Final Report and the Final EIS are
transmitted by OCE to the Office of the Secretary of the Army
(OSA) for review. Following the review, OSA transmits these
documents to the Office of Management and Budget (OMB). OMB
reviews the documents and furnishes OSA with comments which
are then incorporated into the Final Report. OSA then trans-
mits the report to Congress with its recommendations for im-
provements. A copy of this report is sent to CEQ, EPA, the
DE, the Division Engineer, state and local agencies, citizen
groups, and individuals on the project mailing list. OCE
also informs the public that the Final EIS is available for
review.
A-3
-------
(6) Approval. The Senate and House Committee on Public Works
holds open hearings on the Filial Report submitted to Congress
for the purpose of deciding whether or not to include the
project in an omnibus River and Harbor and Flood Control Bill.
If included, the passage of the act will authorize the construc-
tion of the project.
After the hearings, the Committee prepares a report on the
bill under consideration and the proposed bill is brouqht to
the floor of Congress for consideration. Enactment by Congress
and approval by the President are the final steps in authoriza-
tion for construction of the project. Authorization, however,
does not provide funds for planning and construction of the
project. These funds must be secured independently through
the normal procedures of budget presentation and annual ap-
propriation proceedings.
B. Corps Approved Projects
The planning process for Corps-approved projects consists
of the following four steps:
(1) Project Investigation and Findings. The DE undertakes a
reconnaissance study to determine if a detailed study is war-
ranted. If detailed studies are warranted, the DE undertakes
studies to determine the scope and nature of the project. At
ttic same time public meetings are held to assist the DE in
project formulation as well as identification of environmental
concerns. The DE concludes the detailed studies by preparing
a Detailed Project Report (DPR) and a Draft Environmental Im-
pact Statement (DEIS).
(2) Review and Comment. The DE circulates the DEIS and the DPR
to concerned federal, state, and local agencies for review and
comment. At the same time, the DE will circulate the DEIS for
review and comment to other agencies, groups, and individuals
on the project mailing list. In addition, copies of the DEIS
will be furnished directly to CEQ and higher authorities. A
news release informing the public of the availability, of the
DEIS is issued by the CEQ.
After receipt and evaluation of agency review comments,
comments of the interested public, and information obtained
at the public meeting (optional), the DE prepares the Final
Environmental Impact Statement (FEIS) and completes the De-
tailed Project Draft.
The Division Engineer then approves the project formula-
tion, the technical aspects of the project report, and the ade-
quacy of the FEIS and transmits these documents to OCF.
A-4
-------
(4) 'rr.insmi.ttaL. Alitor OCE reviews the nP"v and the. FEIS for
po I. rcV"'-iiK]"7^rocedurc, OCE or OSA will transmit the FI'IS to
CEO. The 1)1:'. aJso furnishes copies of tho FEIS to agencies, groups,
and individuals on the project mailing list and to the appro-
priate state, regional, and metropolitan clearinghouses. In
addition, CEQ issues a news releas informing the public of the
availability of the FEIS.
(4) Approval. At the appropriate time OCE approves the DPR
and authorizes the project. OCE notifies the Division Engineer
who then notifies the governor and interested congressmen of the
project approval.
SOIL CONSERVATION SERVICE81'84
The Watershed Protection and Flood Prevention Act of 1954
(PI, 5 MO , as amended, provides for technical, financial, and
credit assi.stance for watershed planning and program develop-
ment for the conservation of soil and water resources. Local
organizations are responsible for the initiation and develop-
ment of projects. Close cooperation and assistance of local,
state, and federal agencies are generally encouraged.
To be eligible for federal assistance a watershed project
must not exceed 101,000 hectares (250,000 acres) in size, nor
include any single structure which provides more than
J.. 54 x 106 m3 (12,500 acre-feet) of floodwater detention
capacity, nor more than 3.08 x 10^ m^ (25,000 acre-feet) of
total capacity. The planning process for watershed projects
i.s initiated when a sponsor applies for planning assistance
to deal with authorized project purposes. Authorized purposes
winch may involve impoundments include watershed protection,
f l.ood prevention, agricultural water management, public rec-
reation, publ i.c fish and wildlife, municipal and industrial
water supply, and water quality management. The sponsor may
be a state, or political subdivision thereof, soil or water
cons-ervation district, flood control district, or any other
agency having authority to carry out, operate, and maintain
works of improvement. Nonprofit irrigation or reservoir com-
panies, water users' associations, or similar organizations
havmg such authority are also eligible if approved by the
Secretary of Agriculture.
Despite the differences m authorization, all watershed
proiocts employ a similar planning process for the develop-
ment and review of the EIS. This planning process is de-
scribed in the following six step orocedure :
(I) Application Development. Application for planning assist-
ance is initiated and completed by local organizations such as
A-5
-------
water conservation districts. Public meetings to define and
evaluate watershed problems are conducted in concert with the
application development. Comments from state and areawi.de A-95
clearinghouses are received and included in the application.
The application is prepared by the sponsoring organization and
submitted to a designated state agency for approval. If an ap-
plication is disapproved, no further action is taken by the
SCS. The designated state agency may also defer action until a
field examination under the direction of the SCS is conducted
to acquire sufficient information. If the application is ap-
proved,. the state conservationist performs a thorough review and
transmits it to the SCS Administrator. The Administrator ac-
knowledges receipt of the application by notifying the spon-
sors, state conservationist, and appropriate clearinghouses.
(2) Preliminary Investigation. Once a request for planning
assistance has been approved, the state conservationist, with
the assistance of the SCS and participating agencies, conducts
a preliminary investigation of the project. Sufficient infor-
mation is assembled to determine if national and regional
standards are met. Public meetings are held to obtain and
disseminate information, discuss alternatives, and reach a
tentative consensus on the impacts of available alternatives.
Based on the preliminary investigation, the state conserva-
tionist may request authorization to begin planning and prepar-
ation of the EIS.
(3) Detailed Planning. Once the Administrator (SCS) grants
planning authority, appropriate agencies, organizations, and
heads of government are notified. Those notified include the
designated state agency, state conservationist, heads of con-
cerned federal agencies, the sponsoring local organizations,
and appropriate clearinghouses.
With the initiation of planning, a preliminary draft EIS is
prepared by the SCS under the direction of the state conserva-
tionist. Assisting agencies are determined by the state con-
servationist and CEQ guidelines. The guidelines for watershed
projects do not include the EPA as an agency having legal juris-
diction to assist. The Preliminary Draft EIS is then reviewed
and commented on by the public, appropriate clearinghouses, and
other interested local, state, and federal agencies. Following
the informal field review, the state conservationist prepares
the Draft EIS which is reviewed by the Technical Service Center.
(4) Formal Review and Comment. The state conservationist dis-
tributes the Draft EIS for a formal interagency review. Those
included in the review are CEQ, sponsors, heads of governments,
designated state agencies, appropriate state and federal agen-
cies, clearinghouses, and the general public. Review and com-
ment are requested within 60 days. Comments received are used
by the state conservationist in the preparation of the Final
A-6
-------
EIS, which is then reviewed by the Technical Service Center.
(5) Transmittal of EIS. The state conservationist signs and
approves the Final EIS. If the project requires congressional
approval, the Administrator also signs and approves the Final
EIS. Following approval, the Final EIS is transmitted to the
CEQ, to all who commented on the Draft EIS, and to others upon
request.
(6) Authori zation. Final approval to proceed with the project
is given. For congressionally approved projects, the appro-
priate congressional committees approve the project, with the
Administrator authorizing installation. For administratively
approved projects, the state conservationist approves the
project and authorizes installation. In both cases, the state
conservationist notifies appropriate offices of federal and
state agencies, clearinghouses, and others who have indicated
an interest. For congressional plans, the Administrator noti-
fies the Secretaries of HEW, Interior, Labor, Commerce, the FPC,
and the Corps of Engineers.
BUREAU OF RECLAMATION 85'86
The Reclamation Act of 1902 (43 U.S.C. 391 et seq.) auth-
orized the Secretary of the Interior to locate, construct,
operate, and maintain works for the storage, diversion, and
development of waters for the reclamation of arid and semi-
arid lands in the western states. A Reclamation Service was
established in the Geological Survey (later separated from the
Survey and renamed the Bureau of Reclamation) in 1923. In
promoting optimum development of water and related land re-
sources in the seventeen contiguous western states, the Bureau's
program has expanded to include impoundments that may serve some
or all of the following concurrent purposes: irrigation water
service, municipal and industrial water supply, hydroelectric
power generation, flood control, and navigation related uses.
The development of a reclamation project may be initiated
by the Bureau itself or at the request of a local agency or
group. In the latter case, the local sponsors must bear one-
half of the cost of the investigation. The study process en-
tails two major steps. The first step is a preliminary recon-
naissance investigation which is generally defined as recogni-
tion of potential development, the collection of all readily
available information in the particular area, and having as
its chief purpose the determination of whether further invest-
igation is justified. The second step is a feasibility invest-
igation, based on the reconnaissance report, which is conducted
to determine the engineering, economic, and financial feasibility
of a project.
A-7
-------
When a project is proposed, the Commissioner of Reclama-
tion, upon receiving clearance from the Office of the Secretary
of the Interior, directs the appropriate Regional Office of the
Bureau to undertake a reconnaissance investigation. This first
phase study is normally funded from an annual appropriation for
investigation. The Area Development Office in the vicinity of
the proposed project conducts the field investigations. The
Regional Director then uses this information to prepare a recon-
naissance report which is coordinated with interested agencies
and groups.
If the reconnaissance report indicates that further study
of a project is justified, the Bureau then seeks authorization
and funding for a feasibility investigation. The Area Develop-
ment Office where the project is located carries out the feas-
ibility investigation and prepares a draft report that describes
the findings and serves as the basis for receiving construction
authorization. Each of the feasibility components must be an-
alyzed thoroughly. Engineering feasibility relates to the
adequacy of site conditions, hydrology, and other physical fact-
ors influencing design, construction, or operation of the proj-
ect. The economic feasibility criterion specifies that the
project benefits must exceed costs, including the evaluation
of both primary and secondary gains and losses. In addition, a
description of intangible values affected by the proposed proj-
ect must be included. The study of financial feasibility con-
centrates on the equitable distribution of costs among various
project purposes and whether reimbursable costs can be returned
by project beneficiaries.
Several federal agencies, including the EPA, may assist the
Bureau in these feasibility evaluations. The Bureau itself
generally assesses irrigation benefits derived from a proposed
project. Hydroelectric power benefits are evaluated with the
assistance of the Federal Power Commission. The Corps of En-
gineers supplies information concerning flood control and
navigation, both of which are generally nonreimbursable project
benefits. The EPA may be called on to furnish data concerning
water supply and treatment, water quality benefits associated
with the proposed project, or the value of storage allocated
specifically to flow augmentation for quality control. The
Fish and Wildlife Service and the Bureau of Outdoor Recreation
may be consulted for an evaluation of project benefits and
costs in their respective areas of expertise.
After completion of the feasibility studies, the Area De-
velopment Office in charge of the investigation prepares a draft
of a proposed planning report and a draft environmental state-
ment. These are forwarded to the Bureau's Regional Office for
review. The drafts are then circulated for review and comment
to interested local and state agencies and to regional offices
A-8
-------
of interested federal agencies. After further review by na-
tional levels of the Bureau, a final draft of the report is
prepared and submitted to the Secretary of the Interior for
approval and adoption. Comments on the Final Draft are solic-
ited from affected or interested state and federal agencies and
the Secretary's final feasibility report is transmitted to the
Office of Management and Budget, the President, and Congress
for authorization and funding.
Because of federal emphasis on comprehensive planning for
water and related land resources, the Bureau's program has be-
gun to shift from isolated, project-oriented reconnaissance
investigations and reports to more broadly based planning ac-
tivities. As a result, project planning currently falls into
one of three general areas: (1) comprehensive framework (Type
I) studies begun under the Water Resources Planning Act of 1965;
(2) Western United States Water plan which provides reconnais-
sance coverage of 11 of the 17 states in the Bureau's jurisdic-
tion; and (3) reconnaissance type state-wide plans for Kansas,
Colorado, Montana, Nebraska, Oklahoma, and New Mexico which are
not included in the Western United States Water Plan above.
With the exception of some projects for which reconnaissance
studies have been completed, new impoundments will generally
be studied as part of one of the above planning processes.
However, the feasibility phase for individual projects will
be based on information in the more comprehensive reconnaissance
study.
TENNESSEE VALLEY AUTHORITY87
The Tennessee Valley Authority (TVA), a corporation wholly
owned by the federal government, was created by an act of Con-
gress on 18 May 1933. Its basic purpose is to conduct a uni-
fied program of conservation, development, and use of the re-
sources of the Tennessee Valley. The TVA presently operates a
system of dams and reservoirs on the Tennessee River and its
tributaries and investigates the need for, and feasibility of,
additional river control projects in the region. Impoundment
purposes are varied and may include development of navigation,
flood control, hydroelectric power, water supply, recreation,
irrigation, and other beneficial uses of water.
Consideration of the environmental aspects of a proposed
TVA action is to begin at the earliest possible point in the
planning process. The TVA's policies and procedures relating
to implementation of NEPA and EIS's require the preparation of
an Environmental Evaluation Record (EER) when project planning
is initiated. The EER contains three major sections:
A-9
-------
@ A description of the need or opportunity which has
arisen and a preliminary identification of alterna-
tives .
© A proposal and discussion of one or more solutions
that are to be favored in the planning process
® An outline of environmental compliance procedure
These steps are fully coordinated internally within TVA
to uncover alternatives, special environmental problems, and
otherwise assist the initiating office, which in the case of
impoundments is normally the Division of Water Management.
The Division of Environmental Planning works closely with the
initiating office throughout the planning and EIS development
stages of a proposed project.
The outline of environmental compliance procedures lists
both the important steps in the planning process and the
studies and investigations required to assess a proposed ac-
tion. The initiating office also recommends an appropriate
time in the planning process for issuing a draft EIS. The
timing is based on the schedules for studies and the gather-
ing of pertinent environmental information. The EPA and other
Federal or state agencies may be requested to investigate speci-
fic aspects of the proposed project during the planning phase.
Consultation and coordination with non-TVA groups may also take
place through the normal working relationships that have been
established.
After consultation with the Division of Environmental
Planning on the need for additional investigations, relevant
information from the EER (and other studies) is synthesized
into a preliminary draft EIS. This preliminary draft is re-
viewed by offices and divisions within TVA, revised as necessary,
and transmitted to the General Manager who may approve or reject
the document. If rejected, the draft is returned with instruc-
tions for revisions. When the General Manager approves the
preliminary draft, it becomes the Draft Environmental Impact
Statement and is submitted to CEQ and to interested agencies and
groups for external review. The DEIS is subject to CEQ guidelines
and procedures established pursuant to the Office of Management
and Budget Circular A-95.
Special environmental studies conducted with the TVA and by
other agencies during planning for a proposed impoundment pro-
ject will normally be summarized and referenced in the Draft EIS.
The reviewer should be able to contact the agency responsible
for investigating a certain environmental aspect of a project,
or obtain the original report, if he has questions on informa-
tion included in the EIS.
A-10
-------
FEDERAL POWER COMMISSION88
The use of hydroelectric power is regulated at the federal
level by the Federal Power Commission (FPC). The FPC is an
independent agency of the federal government originally es-
tablished in 1920 under the Federal Water Power Act. This Act
extended federal control over water power development on naviga-'
ble streams. The Commission's authority covers the licensing
and regulation of both conventional and pumped-storage hydro-
electric projects.
An applicant for an FPC license may be a utility company,
a private business or association, an individual, a municipal-
ity, or a state. The FPC's guidelines concerning implementa-
tion of the NEPA require that all applications for major pros-
pects (those in excess of 2,000 horsepower) or for reservoirs
which only provide regulatory flows to downstream major hydro-
electric projects shall be accompanied by the applicant's de-
tailed statement on environmental considerations (Exhibit W).
The same requirement also applies to applications for license
amendments which propose changes in construction or operation
of a project. This report is one of several exhibits which
the applicant must prepare and submit to the FPC along with the
license application. If, after an initial review of the materials
submitted, it is determined that the proposal will be a major
federal action significantly affecting the quality of the
human environment, the Commission staff will proceed to prepare
an environmental impact statement. Often the applicant's Ex-
hibit W is used to supply much of the information eventually
included in an EIS.
Other exhibits of particular interest to the EIS reviewer
are Exhibit H, the operation of the project with respect to
water use and quality; Exhibit R, the recreation plan; and Ex-
hibit S, the impact on fish and wildlife. Applicant's are ex-
pected to have consulted with appropriate federal, regional,
state, and local entities during the preliminary planning
stages for the purpose of identifying relevant environmental
factors. As these exhibits may contain a considerable amount
of background information which is not always put into the EIS,
the reviewer should make sure he has copies of them to assist
in the impact evaluation.
The question of low-flow augmentation at FPC projects is
specifically addressed in Section 102 of the Federal Water Pol-
lution Control Act Amendments of 1972. The law states that:
No license granted by the Federal Power Commission
for a hydroelectric power project shall include storage
for regulation of streamflow for the purpose of water
quality control unless the Administrator (of EPA) shall
recommend its inclusion....
A-ll
-------
Evaluation of a water quality storage proposal should be con-
ducted in accordance with the EPA's policy on low-flow augmenta-
tion. Although the reviewer of a project EIS would not normally
be responsible for this evaluation, he should be acquainted with
any water quality concerns raised in those cases where flow reg-
ulation for water quality control has been studied by EPA.
WATER RESOURCES COUNCIL AND RIVER BASIN COMMISSIONS - WATER RESOURCES
PLANNING ACT89
The Water Resources Planning Act of 1965 has as its stated
purpose:
...to provide for the optimum development of the Nation's
natural resources through the coordinated planning of water
and related land resources, through the establishment of a
water resources council and river basin commissions, and
by providing financial assistance to the states in order
to increase state participation in such planning.
The Water Resources Council is composed of the Secretaries
of Interior; Agriculture; Army; Health, Education and Welfare;
Transportation; and the Chairman of the Federal Power Commission.
The Council has primary responsibility for continuing stud-
ies and periodic assessments of the adequacy of water supplies
in the United States. The Council also reviews water and re-
lated land resource plans prepared by river basin commissions,
or by interagency coordinating committees, and formulates rec-
ommendations on these plans prior to transmittal to the Presi-
dent and Congress.
The Water Resources Planning Act directed the Council to
establish guidelines for water resource planning as well. The
"Principles and Standards for Planning Water and Related Land
Resources"^ provides guidance for developing comprehensive plans
through the coordinated efforts of federal, state, and local
governments, private businesses and organizations, and individ-
uals. The standards apply to the impoundment planning and eval-
uation studies normally carried out by federal agencies as well
as to river basin commissions, federal-state interagency or co-
ordinating committees, and other entities engaged in comprehen-
sive water resource planning with coordinated federal technical
or financial assistance.
River basin commissions created under the 1965 Act serve to
coordinate federal, state, interstate, local, and nongovern-
mental water and related land resources development plans in
A-12
-------
their areas. The commissions may undertake and encourage stud-
ies of problems that relate to the preparation or updating of a
comprehensive and coordinated plan for water resource develop-
ment. The commissions may make recommendations concerning in-
dividual water projects included in a comprehensive plan.
The Water Resources Council defines three levels of plan-
ning: Level A, framework studies and assessments; Level B,
regional or river basin plans; and Level C, implementation
studies. The framework studies are comprehensive evaluations
of regions with complex water resource problems that require
interagency and interdisciplinary coordination. The framework
study may lead directly to recommendations for undertaking im-
plementation studies without further study or to "Level B" plan-
ning at the river basin, sub-basin or regional level.
This second level of planning addresses the complex, long-
range problems identified in the framework studies through re-
connaissance-type studies. A federal agency, such as a river
basin commission, the Bureau of Reclamation, or the Corps of
Engineers may take the lead for coordinating interagency in-
volvement in the development of a regional or river basin plan.
Section 209 (a) of the Federal Water Pollution Control Act
Amendments of 1972 provides that Level B plans must be com-
pleted by the Water Resources Council for all river basins
in the United States by 1980.
Implementation studies are program or project feasibility,
studies and are usually undertaken by a single federal, state,
or local agency. Their purpose is to carry out the recommenda-
tions contained in higher level plans. In the case of federal
impoundments, the planning process would be comparable to that
used by the various agencies involved. Such plans are oriented
to near-term needs; those that require action within 10 to 15
years.
The reviewer of an impoundment EIS is specifically con-
cerned with Level C, the implementation study phase of a pro-
posed project. It should be noted, however, that if more
comprehensive Level A, Level B, or similar studies, have pre-
ceded planning for an individual project they may contain
considerably more information on regional characteristics,
interrelationships with other existing or planned water re-
source developments, alternatives, and other factors than is
found in the EIS. The Water Resources Council planning stand-
ards call for a full evaluation of "without project" and "with
project" conditions and an accounting of beneficial and/or ad-
verse effects in the four categories: national economic de-
velopment, environmental quality, regional development, and
social well-being. The standards also discuss quantification
of these effects, either in monetary terms or otherwise.
Since the EIS for an impoundment is apt to be the product
A-13
-------
of numerous carl ier planning and environmental studies, the
reviewer should refer, if necessary, to these documents for back-
ground information and data on the project. Planning studies
done under the auspices of the Water Resources Council may be
particularly useful for tracing the development of a project
and understanding its basin-wide implications.
FISH AND WILDLIFE SERVICE - FISH AND WILDLIFE COORDINATION ACT
The major activities of the United States Fish and Wildlife
Service occur under the authorization of the Fish and Wildlife
Coordination Act of 1934, as amended. The Bureau of Sport Fish-
eries and Wildlife was established in the Department of the In-
terior by the Fish and Wildlife Act of 1956, as amended. This
Bureau is directly involved with environmental coordination of
federal water resource development efforts. Enabling legisla-
tion provides that fish and wildlife conservation, protection,
and enhancement receive equal consideration along with other
water resources project purposes. Furthermore, any federal
agency or licensee proposing to modify or control any stream
of water body must first consult with the Fish and Wildlife
Service and with the fish and wildlife agencies in the
state(s) in which a project is to be located.
One of the six regional offices of the Bureau of Sport Fish-
eries and Wildlife, Division of River Basin Studies, will be
responsible for carrying out the duties of the Fish and Wild-
life Service under the Fish and Wildlife Coordination Act. The
Bureau staff normally conducts surveys and investigations con-
currently with ongoing planning, feasibility, or other studies
by the lead agency. Their report contains an inventory of fish
and wildlife species; habitat types in the proposed project
area, including any rare, endangered, or other unique biota,'
the probable beneficial and/or adverse effects of the project
on these resources; means to mitigate damages; and ways to de-
velop and improve fish and wildlife values. The report and
recommendations of concerned state fish and wildlife agencies
accompany any report submitted by the originating agency to
Congress. The views expressed in the report are also usually
integrated into the Draft Environmental Impact Statement for a
proposed project.
The Bureau of Sport Fisheries and Wildlife generally be-
comes involved early in the planning process in the case of the
Corps of Engineers projects, the Bureau of Reclamation projects,
and in the EIS review phase.
The Fish and Wildlife Service may or may not conduct stud-
ies of proposed small watershed projects of the Soil Conserva-
tion Service. State fish and wildlife agencies will normally
investigate such proposed projects whether or not the Service
participates directly.
A-14
-------
For hydroelectric projects under the jurisdiction of the
Federal Power Commission, a report on fish and wildlife re-
sources (Exhibit S) must be submitted with applications for
licensing or relicensing. The exhibit should describe the
effects of the project on fish and wildlife resources in the
project area, or in other areas affected by the project, and
potential mitigation or enhancement measures. The applicant
for a license prepares the report "on the basis of studies
made after consultation and in cooperation with the U.S. Fish
and Wildlife Service, Department of the Interior, and appro-
priate state fish and wildlife agencies...". The Fish and
Wildlife Service reviews Exhibit S and the applicant's Draft
Environmental Impact Statement (Exhibit W) and recommends license
stipulations and other requirements relating to conservation and
development of fish and wildlife resources affected by the
project.
The reviewer should regard the Fish and Wildlife Service
as a source of technical assistance in all areas of fish and
wildlife conservation and management, particularly with re-
spect to ecological impacts of flow regime, thermal regime,
water quality, and habitat changes resulting from impoundment.
A-15
-------
1
2
3
4
5
6
7
8
9
10
11
12
REFERENCES
Funk, J.L and Ruhr, C.E., "Stream Channelization in the
Midwest," E. Schneberger and J.L. Funk, ed., "Stream
Channelization: A Symposium," American Fisheries Society,
Special Publication No. 2, 1971.
U.S. Environmental Protection Agency, "Review of Federal
Actions Affecting the Environment," EPA Transmittal No. 2,
Mar. 1, 1975.
Council on Environmental Quality, "Preparation of Environ-
mental Impact Statements," Vol. 38, No. 147, Aug. 1, 1973.
"Preparation of Water Quality Management Basin Plans,"
Title 40 Code of Federal Regulations, Part 131.
Hagan, R.M. and Roberts, E.B., "Ecological Impacts of
Water Projects in California," Journal of the Irrigation
and Drainage Division, ASCE, Vol. 98, No. IRl, Mar. 1972.
Warner, M.L., et al., "An Assessment Methodology for the
Environmental Impact of Water Resource Projects," EPA-
600/5-74-016, Washington, EPA, Office of Research and
Development, July 1974.
Tennessee Valley Authority, "Final Environmental State-
ment, Tellico Project, Vol. I," Feb. 10, 1972.
U.S. Environmental Protection Agency, "Policy on Storage
and Releases for Water Quality Control in Reservoirs
Planned by Federal Agencies," Jan. 16, 1973.
Skogerboe, G.V., "Role of Water Delivery Systems in Water
Quality," Age of Changing Priorities for Land and Water,
Irrigation and Drainage Division Specialty Conference,
Spokane, Wash., 1972.
Wells, D.M., Chrmn., "Agricultural Waste Management, by
the Committee on Agricultural Waste Management of the
Environmental Engineering Division," Journal of the En-
vironmental Engineering Division, ASCE, Vol. 100, No. EE1,
Feb. 1974.
U.S. Environmental
for Water Quality,
National Technical
Quality Criteria,"
Protection Agency,
Vol. I," Washington
Advisory Committee,
Washington, Apr. 1,
"Proposed Criteria
, 1973.
FWPCA, "Water
1968.
R-l
-------
13. Jenke, A.L., "Evaluation of Salinity Created by Irrigation
Return Flows," EPA 430/9-74-006, Washington, EPA, Office
of Water Program Operations, Nonpoint Source Control Branch,
Jan. 1974.
14. U.S. Environmental Protection Agency, Office of Air and
Water Programs, "Methods for Identifying and Evaluating
the Nature and Extent of Nonpoint Sources of Pollution,"
EPA 430/9-73-014, Washington, EPA, Oct. 1973.
15. Sylvester, R.O. and Seabloom, R.W., "Influence of Site
Characteristics on Quality of Impounded Water," Journal
of the American Water Works Association, 57:1528-1546,
Dec. 1965.
16. U.S. Environmental Protection Agency, "The Control of
Pollution from Hydrographic Modifications," Washington,
Oct. 1973.
17. Kittrell, F.S., "Effects of Impoundments on Dissolved
Oxygen Resources," Sewage and Industrial Wastes, Vol. 31,
No. 9, Sept. 1959.
18. Ingols, R.S., "Effect of Impoundment on Downstream Water
Quality, Catawba River, S.C.," Journal of the American
Water Works Association, 51:42-46, Jan. 1959.
19. Churchill, M.A., "Effects of Impoundments on Oxygen
Resources," Oxygen Relationships in Streams, Technical
Report W58-2, Cincinnati, Ohio, Taft Sanitary Engineer-
ing Center, Mar. 1958.
20. Warner, M.L. et al. , "An Assessment Methodology for the
Environmental Impact of Water Resource Projects," EPA-
6 0 0/5-7 4-016, Washington, EPA, Office of Research and
Development, July 1974.
21. Bohan, J.P. and Grace, J.L., Jr., "Selective Withdrawal
from Man-Made Lakes," Technical Report H-73-4, U.S. Army
Engineer Waterways Experiment Station, Hydraulics Lab-
oratory, Vicksburg, Miss., Mar. 1973.
22. Brooks, N.H. and Koh, R.C.Y., "Selective Withdrawal from
Density-Stratified Reservoirs," Journal of the Hydraulics
Division, ASCE, Vol. 95, Mo. HY4, July 1969.
23. Imberger, J. and Fischer, II.B., "Selective Withdrawal
from a Stratified Reservoir," Water Pollution Control
Research Series (15040 EJZ 12/70), Washington, EPA,
Dec. 1970.
R-2
-------
24. Wunderlich, W.O. and Elder, R.A., "Effect of Intake Eleva-
tion and Operation on Water Temperature," Journal of the
Hydraulics Division, ASCE, Vol. 95, No. HY6, Nov. 1969.
25. Buckman, H.O. and Brady, N.C., "The Nature and Properties
of Soils," 6th ed., New York, The MacMillan Co., 1960.
26. Uttorraark, P.D., Chapin, J.D., and Green, K.M., "Estimat-
ing Nutrient Loadings of Lakes from Non-Point Sources,"
EPA-660/3-74-020, Washington, EPA, Office of Research and
Development, Aug. 1974.
27. Massachusetts Institute of Technology, "A Predictive
Model for Thermal Stratification and Water Quality in
Reservoirs," 1613ODJII01/71.
28. Krenkel, P.A., Thackston, E.L., and Parker, F.L., "Im-
poundment Effect on Waste Assimilation," Journal of the
Sanitary Engineering Division, ASCE, Vol. 95, No. SAl,
Feb. 1967.
29. Vanderhoof, R.A., "Changes in Waste Assimilative Capacity
Resulting from Streamflow Regulation," in "Symposium on
Streamflow Regulation for Quality Control," Public Health
Service Publication No. 999-WP-30, 1065.
30. Ward, J.C., and Karaki, S., "Evaluation of Effect of Im-
poundment on Water Quality in Cheney Reservoir," Bureau
of Reclamation Research Report No. 25, Washington, U.S.
Government Printing Office, 1971.
31. Water Resources Engineers, "Mathematical Models for- the
Prediction of Thermal Energy Changes in Impoundments,"
Water Pollution Control Research Series 16130DHS07/60,
July 21, 1969.
32. Ortolano, L., Ringel, D.J., and Jones, J.R., "Environ-
mental Impacts Associated with Reservoir Projects,"
Ortolano, L., ed., "Analyzing the Environmental Impacts
of Water Projects," U.S. Army Engineer Institute for
Water Resources, NTIS Ad-766 286, Mar. 1973.
33. Virginia Polytechnic Institute, "Legal Aspects of Water
Storage for Flow Augmentation, Appendix II, Typical
Corps of Engineers Contract," EPA, Water Quality Office,
Water Pollution Control Research Series Report 16090
FPW 03/70, Aug. 1970.
34. "Preparation of Water Quality Management Basin Plans,"
Title 40 Code of Federal Regulations, Part 131.304.
R-3
-------
35. U.S. Environmental Protection Agency, "Policy on Storage
and Releases for Water Quality Control in Reservoirs
Planned by Federal Agencies," Jan. 16, 1973.
36. Gordon, R.N., "Fisheries Problems Associated with Hydro-
electric Power Development," Canadian Fish Culturist,
35:17-36, Oct. 1965.
37. Fraser, J.C., "Regulated Dischrage and the Stream En-
vironment," "River Ecology and Man," R.T. Oglesby,
et. al., ed., New York, Academic Press, 1972.
38. U.S. Environmental Protection Agency, "Effect of Meteor-
ological Variables on Temperature Changes in Flowing
Streams," EPA-660/3-75-002, Vanderbilt University, Jan.
1975.
39. Edinger, Brady and Geyer, "Heat Exchange and Transport
in the Environment," Report No. 14, Cooling Water Dis-
charge Research Project, Electric Power Research In-
stitute, Palo Alto, ERRF Publication No. 74-049-00-3,
Nov. 3, 1974.
40. Lehmkuhl, D.M., "Change in Thermal Regime as a Cause of
Reduction of Benthic Fauna Downstream of a Reservoir,"
J. Fish. Research Bd. Canada, Vol. 29, No. 9, Sept. 1972.
41. Hynes, H.B.N., "The Ecology of Running Waters," Univ.
Toronto Press, Toronto, Ont., 1970.
42. Hoffman, C.E. and Kilambi, R.V., "Environmental Changes
Produced by Cold-Water Outlets from Three Arkansas Reser-
voirs," Water Resources Research Center Publication No. 5,
Univ. of Arkansas, Fayetteville, Arkansas, 1971.
43. Pfitzer, D.W., "Evaluation of Tailwater Fishery Resources
Resulting from High Dams," C.E. Lane, Jr., ed., "Reservoir
Fishery Resources Symposium," Southern Division, American
Fisheries Society, Univ. of Georgia, 1967.
44. Beininger, K.T. and Ebel, W.J., "Effects of John Day Dam
on Dissolved Nitrogen Concentrations and Salmon in the
Columbia River, 1968," Trans. American Fisheries Society,
Vol. 99, No. 4, Oct. 1970.
45. Boyer, P.B., "Gas Supersaturation Problem in the Columbia
River," "Age of Changing Priorities for Land and Water,"
Proceedings of the ASCE Irrigation Division Specialty
Conference, Spokane, Wash., Sept. 26-28, 1972.
R-4
-------
46. Wright, J.C., "Effect of Impoundments on Productivity,
Water Chemistry and Heat Budgets of Rivers," C.E. Lane,
Jr., ed., "Reservoir Fishery Resources Symposium," South-
ern Division, American Fisheries Society, Univ. of Georgia,
1967.
47. U.S. Environmental Protection Agency, "Guidelines of the
Environmental Protection Agency Regarding Storage and
Releases for Water Quality Control in Reservoirs Planned
by Federal Agencies," Jan. 16, 1973.
48. State of Vermont, Agency of Environmental Conservation,
Water Resources Board, "Regulations Governing Water
Classification and Quality Control," adopted in accord-
ance with 10 V.S.A. 905(a) (12), Dec. 20, 1973.
49. Sciandrone, J.C., "Environmental Protection at California
Dam," Civil Engineering, Vol. 44, No. 3, Mar. 1974.
50. Katzer, M.F., "Control of Turbidity at Construction Sites,"
Economical Construction of Concrete Dams, Proceedings of
the Engineering Foundation Conference, ASCE, New York,
May 14-18, 1972.
51. U.S. Environmental Protection Agency, Office of Air and
Water Programs, "Processes, Procedures and Methods to
Control Pollution Resulting from all Construction Ac-
tivity," EPA 430/9-73-007, Washington, Oct. 1973.
52. Fair, G.M. and Geyer, J.C., "Water Supply and Waste Water
Disposal," John Wiley & Sons, New York, 1954.
53. McCullough, C.A. and Nicklen, R.R., "Control of Water Pol-
lution During Dam Construction," Journal of the Sanitary
Engineering Division, ASCE, Vol. 97 No. SAl, Feb. 1971.
54. Allen, E.J., "Taste and Odor Problems in New Reservoirs
in Wooded Areas," Journal AWWA, 52:1027-1032, Aug. 1960.
55. U.S. Environmental Protection Agency, "The Control of
Pollution from Hydrographic Modifications," Washington,
1973 .
56. Austin, G.H., Gray, D.A., and Swain, D.G., "Multilevel
Outlet Works at Four Existing Reservoirs," Journal of
the Hydraulics Division, ASCE, Vol. 95, No. HY6, Nov.
1969.
57. Glymph, L.M., "Summary: Sedimentation of Reservoirs,"
W.C, Ackermann, G.F. White and E.B. Worthington, ed.,
Man-Made Lakes: Their Problems and Environmental Ef-
fects , Geophysical Monograph 17, American Geophysical
Union, Washington, 1973.
n r
-------
58. Love, S.K., "Relationship of Impoundment to Water Quality,"
Journal of the American Water Works Association, Vo1. 5 3,
No. 5, May 1961.
59. Speece, R.E., "Hypolimnion Aeration," Journal AWWA, Vol.
63, No. 1, Jan. 1971.
60. Bohan, J.P. and Grace, J.L., Jr., "Selective Withdrawal
from Man-Made Lakes," U.S. Army Engineer Waterways Ex-
periment Station, Hydraulics Laboratory, Technical Report
H-73-4, Vicksburg, Miss. Mar. 1973.
61. Wunderlich, W.O. and Elder, R.A., "Mechanics of Flow
Through Man-Made Lakes," W.C. Ackermann, G.F. White, and
E.B. Worthington, ed., Man-Made Lakes: Their Problems
and Environmental Effects, Geophysical Monograph 17,
American Geophysical Union, Washington, 1973.
62. Stroud, R.H. and Martin, R.G., "Influence of Reservoir
Discharge Location on the Water Quality, Biology and
Sport Fisheries of Reservoirs and Tail Water," W.C. Ack-
ermann, G.F. White, and E.B. Worthington, ed., Man-Made
Lakes: Their Problems and Environmental Effects, Geo-
physical Monograph 17, American Geophysical Union, Wash-
ington, 1973.
63. Wisniewski, T.F., "Improvement of the Quality of Reser-
voir Discharges Through Turbine or Tailrace Aeration,"
in "Symposium on Streamflow Regulation for Quality Con-
trol," Public Health Service Publication No. 999-WP-30,
1965.
64. Raney, D.C. and Arnold, T.G., "Dissolved Oxygen Improve-
ment by Hydroelectric Turbine Aspiration," Journal of
the Power Division, ASCE, Vol. 99, No. P01, May 1973.
65. Elder, R.A., Smith, M.N., and Wunderlich, W.O., "Aeration
Efficiencies of IIowell-Bunger Valves," Journal of the
Water Pollution Control Federation, Vol. 41, Ho. 4,
Apr. 1969.
66. U.S. Environmental Protection Agency, Office of Air and
Water Programs, Division of Water Quality and Non-Point
Source Control, and the Office of Research and Develop-
ment, National Eutrophication Research Program, "Measures
for the Restoration and Enhancement of Quality of Fresh-
water Lakes," EPA-430/9-73-005, Washington, EPA, 1973.
67. Toetz, D., Wilhm, J., and Summerfelt, R., "Biological
Effects of Artificial Destratification and Aeration in
Lakes and Reservoirs - Analysis and Bibliography," Bu-
reau of Reclamation Report REC-ERC-72-33, Denver, Oct.
1972.
"D _ r
-------
68. Department of the Army, Office of the Chief Engineers,
"Recreation Planning and Design Criteria," Engineer
Manual No. 1110-2-400, Sept. 1, 1971.
69. "Thermal Processing and Land Disposal of Solid Waste,"
Federal Register, Vol. 39, No. 158, Part III, Aug. 14,
1974 .
70. "Pesticides and Containers; Acceptance, Disposal, and
Storage," Federal Register, Vol. 39, No. 85, Part IV,
May 1, 1974, and Vol. 39, No. 200, Part I, Oct. 15,
1974.
71. Little, H.R., "Design Criteria for Solid Waste Management
in Recreational Areas," EPA, Solid Waste Management Series
Report (SW-91ts), 1972.
72. U.S. Environmental Protection Agency, Office of Air and
Water Programs, Office of Air Quality Planning and Stand-
ards, "Compilation of Air Pollutant Emission Factors,"
Second Edition, AP-42, Apr. 1973.
73. U.S. Environmental Protection Agency, "Guidelines for
the Review of Environmental Impact Statements: Vol. I,
Highway Projects," Sept. 1973.
74. "Preparation of Water Quality Management Basin Plans,"
Title 40 Code of Federal Regulations, Chapter 1, Part
52.22 (b) .
75. Memphis State University, "Effects of Noise on Wildlife
and Other Animals," Washington,EPA, Office of Noise Abatement
and Control, 1971.
'76. U.S. Environmental Protection Agency, Office of Noise
Abatement and Control, "Information on Levels of Environ-
mental Noise Requisite to Protect Public Health and Wel-
fare with an Adequate Margin of Safety," 550/9-7 4-004,
Mar. 1974.
77. U.S. Environmental Protection Agency, U.S. Office of
Noise Abatement and Control, "Noise Source Abatement
Technology and Cost Analysis Including Retrofitting,"
(NTID 73.5), July 27, 1973.
78. "Administrative Procedures, Environmental Impact State-
ments," Title 33 Code of Federal Regulations, Part 209.
79. Office of the Chief of Engineers, Department of the Army,
"Engineering Manual: Survey Investigations and Reports,
General Procedures," revised through Aug. 29, 1969.
R-7
-------
80.- Office of the Chief of Engineers, Department of the Army,
"Preparation and Coordination of Environmental Statements,"
Apr. 15, 1974.
81. "Compliance with NEPA," Title 7 Code of Federal Regulations,
Part 650.
82. United States Department of Agriculture, "USDA Procedures
for Planning Water and Related Land Resources," Mar. 1974.
83. Soil Conservation Service, United States Department of
Agriculture, "Watershed Protection Handbook: Part I -
Planning and Operations," Aug. 1967, updated through May 1,
1974.
84. Soil Conservation Service, United States Department of Agri-
culture, "Environmental Impact Statements: Guidelines for
Preparation," Federal Register, Vol. 39, No. 107, June 3,
1974 .
85. Reclamation Instruction Series 350, Part 376, "Environ-
mental Quality - Preservation and Enhancement," Bureau
of Reclamation.
86. Ely, N., "Authorization of Federal Water Projects," NTIS
PB-206 096, National Water Commission, Arlington, Va.,
Nov. 1971.
87. Tennessee Valley Authority, "Environmental Quality Manage-
ment: Policy and Procedures," Federal Register, Vol. 39,
No. 2, Feb. 14, 1974.
88. Federal Register, Vol. 38, No. 117, June 19, 1973.
89. "Principles and Standards for Planning Water and Related
Land Resources," Federal Register, Vol. 38, No. 174,
Sept. 10, 1973.
R-8
------- |