Williams, R. 1985. Report on the Loss of Salmonid Fish at the Winchester Hydroelectric
Project in 1984. Oregon Department of Fish and Wildlife, Research and
Development Station.

Williams, I. V., and J. R. Brett. 1987. Critical Swimming Speed of Fraser and Thompson
River Pink Salmon (Oncorhynchus gorbuscha). Canadian Journal of Fisheries and
Aquatic Sciences, 44 pp 348-356.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 53


rane PIER

WATER ELEVATION

BAY Yew .
FLOW NUNN VUNMUNUUCC]
’ FLOW
FLAT BAR STEEL WITH MAXIMUM —>

4” CLEAR OPENING
(DEPENDING ON SPECIES) lS

SHH

335 nee HT rt t

sseteee SEESSSSESSSSSSOSSEEEEE y
SEES ESS SSR cece
eS SES ae

os
HSS SSE i
= aS

SSS

FIGURE 32

VERTICAL OR INCLINED
DIFFUSER BARRIER

TAILRACE BARRIER STUDY
SOURCE: WOOIFIED FROM NWES 1999

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 19


Stone & Webster Environmental Technology & Services prepared this report, and
it does not necessarily reflect the views of the staff of the Federal Energy Regulatory
Commission.



Annotated Bibliography

Bulow, F.J., W. D. Crumby, S. S. Quisenberry, M. A. Webb. 1988. Effectiveness of a fish
barrier dam in limiting movement of rough fishes from a reservoir into a tributary stream.
North American Journal of Fisheries Management. Vol. 8 pp 273-275.

ee
ees
es

ROUGH FISH
FISH BARRIER DAM

LOCATION OF STUDY:

Roaring River, tributary to Cordell Hull Reservoir on the Cumberland River, Tennessee.

PROJECT CHARACTERISTICS: N/A

I ‘HARA\ RISTICS: N/A
PROJECT TRE. ISH PASSAGE: N/A
TAILRACE BARRIER DESIGN:

A fish barrier dam was constructed on the Roaring River near where it empties into the
Cordell Hull Reservoir. The fish barrier was constructed of steel, filled with stones, and
reinforced with a concrete cap (after it was damaged by storm waters). The barrier is 69.2
meters in length and extends across the entire width of the river. The barrier crest is 3.45
meters above the downstream minimum pool elevation (152 meters).

BIOLOGICAL EFFECTS OF TAILRACE BARRIER:

The fish barrier dam was constructed across the Roaring River to prevent rough fish in the
reservoir from moving upstream into the river. An evaluation of the barrier found it to be
highly effective at excluding seven species of rough fish. River flow alterations caused by
the barrier have produced silted areas extending about 3 kilometers upstream. The
observed siltation could negatively affect resident fish populations located upstream of the
barrier.

TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A
COMMENTS:

This paper describes the design and biological effectiveness of a fish barrier that was
constructed solely for preventing the movement of undesirable fish species into a tributary

Page 62 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

Haynes, J. M., and R. H. Gray. 1980. Influence of Little Goose Dam on upstream
movements of adult chinook salmon, Oncorhynchus tshawytscha. Fishery Bulletin 78(1):185-
190.

CHINOOK SALMON

l FALSE ATTRACTION
MIGRATION DELAY

LOCATION OF STUDY:

Little Goose Dam, lower Snake River, Washington.

PROJECT CHARACTERISTICS:

No information was provided with respect to the design and operation of the hydroelectric
facilities at the Little Goose Dam.

BIOLOGICAL CHARACTERISTICS:

Adult chinook salmon migrate annually to spawning areas upstream of the Little Goose
Dam.

PR STREAM FISH PASSAGE:

The Little Goose Dam is an impediment to upstream migrants, consequently, fish ladders
have been installed to allow fish to pass upstream.

TAILRACE BARRIER DESIGN: N/A
BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A
TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A

MMENTS:
This study examined migration delays of adult chinook salmon encountering the Little
Goose Dam. The average passage delay for radio-tagged and control fish combined was 216
hours in 1976 and 90 hours in 1977. At the Lower Granite Dam, which is upstream of the

Little Goose Dam, passage delays of the same fish were less than 50 hours in 1976 and 58
hours in 1977. The passage delays recorded for chinook salmon in 1976 were significantly

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 73


Williams 1985; Brown 1991). There is
little information, however, on migration
delays for Atlantic salmon, clupeids, and
other species that may undertake spawning
migrations in rivers. Effects of delay may
be extrapolated, however, from studies
conducted with other species if differences
in spawning parameters (e.g., time of year,
duration of spawning period, length of
migration) and biological characteristics
(e.g., energy reserves, swimming
capabilities) are considered.

Assuming that fish passage facilities
are present at a project, migration delays
can result from attraction to non-fishway
flows or inadequate fishway entrances.
The following discussion examines these
two issues and the effects of migration
delay on spawning success.

Ise_At ion

For migratory fish, false attraction
occurs when upstream migrants are
attracted to turbine discharge or spillway
flows rather than to fishway flows. False
attraction also occurs when upstream
migrants detect the scent of their natal
stream downstream of its natural outlet
(Fretwell 1989). This happens when water
from a natal stream is diverted through a
canal or pipe to a hydroelectric project.
In either instance, without proper project
design or operation modifications, there
may be extensive migratory delays.

The scent of natal waterbodies can
be influenced by the upstream
impoundment. At the Green Peter Dam
on the Santiam River the reservoir is
stratified. Returning adult fish are
attracted to the juvenile outmigrant

discharge structure which spills reservoir
surface waters. Adults could not be
attracted to the fishway which is served by
a deep reservoir water supply because as
juveniles they were not imprinted with the
scent of the deep reservoir waters (Bates
1992).

When confronted with several flow
alternatives, upstream migrants typically
are attracted to the flow with the greatest
velocity (Weaver 1963). Therefore, fish
may not locate or enter the fishway if
spillway or turbine discharge velocities are
considerably greater than fishway entrance
velocities.

At hydroelectric projects without
river bypass reaches, fishway entrances
usually are located adjacent to draft tube
outlets and spillways. Migrants are
attracted to turbine discharge and spillway
flows when velocities and volumes are
greater than fishway flows. Long spillway
training walls can also become a barrier
when periodic spill flows attract fish away
from the powerhouse and fish passage
channel. This can also lead to migration
delay.

At sites where the spillway is not
adjacent to the powerhouse (e.g., sites
with upstream diversion dams and power
canals or pipelines), fish may or may not
use the bypassed reach of river for
migration (Department of Fisheries,
Canada 1958, 1962; IPSFC 1976; Schadt et
al. 1985; PacifiCorp 1993). At the Sultan
Project in Washington, a berm was used to
concentrate bypass flows to the
powerhouse side of the channel and
attract fish from the tailrace into the
bypass. Many projects with a long bypass

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 9


Annotated Bibliography

A tentative modification in the project operations during the spring migration consisted of
100 to 200 cfs released downstream of the project diversion dam in conjunction with power-
house shut-downs and an artificial freshet of 400 cfs produced once a week for 6 hours.
Screens were installed in 1956 at the tailrace outlets and were designed to reduce draft tube
injuries, not to minimize migration delays. (Note: no information was provided with respect
to screen dimensions or design.) After the evaluations of the modified project operations
and the tailrace screens were completed, a third approach to reducing migration delays and
fish injury and mortality was recommended. The third approach consisted of a barrier dam
and fish collection facility located immediately downstream of the powerhouse. Fish cap-
tured at the collection facility would be transported upstream to designated release points.

BI ICAL EF

The modified project operations (i.e., timed diversion dam releases and powerhouse shut-
downs) were successful in diverting some upstream migrants away from the powerhouse.
However, it was noted that many fish were still delayed and injured at the tailrace and
powerhouse. The tailrace outlet screens were considered ineffective because large numbers
of seriously injured fish were still being observed after the screens were installed. There was
no indication from this study that either the modified project operations or the tailrace
screens were producing additional migration delays or injuries.

TAILRACE BARRIER EFFECTS ON PROJECT OPERATION:

There was no discussion of how modified flows or tailrace screens and barriers affected
project operation. It was noted, however, that the project owners would not be receptive
to a permanent schedule of powerhouse shut-downs and increased water releases, which
most likely would result in lost generation revenues. Also, there would be annual costs
associated with the use of screens or a tailrace barrier. It was suggested that a flow release
plan could be developed that minimized effects on adult salmon migrations and spawning
and maximized power generation from available flows.

COMMENTS:

This study presents reasonable evidence that tailrace flows were resulting in migration delays
and fish injury at the Puntledge powerhouse. The observed injuries, however, cannot be
conclusively linked to contact of draft tube walls because fish were recovered upstream of
the powerhouse not in the tailrace. Also, this study was not designed to specifically assess
injury and mortality to upstream migrants entering the draft tubes. A discussion of other
sources for fish injury or a more detailed study may have provided additional support for
the conclusion that fish were being injured in the powerhouse draft tubes. This study does
demonstrate that tailrace flows can delay spawning migrations and that modified project
operations may alleviate these delays.

Page 68 Impacts of Hydroelectric Plant Tailraces on Fish Passage


LENGTH OF APRON
WATER ELEVATION |

DEPENDENT ON SWIMMING

NON eer ABILITY OF TARGET SPECIES

MAXIMUM DEPTH = 5“

FLOW MINIMUM VELOCITY = 15 F.P.S.

HIGH DESIGN T.W

TAILWATER
ELEVATION

FIGURE 37

VELOCITY BARRIER

TAILRACE BARRIER STUDY
SOURCE: MODIFIED FROM MMS 1993

Page 26 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

be shallow (maximum of 6 inches). The water velocity and depth requirements are based
on the swimming capabilities of Pacific salmonids and are subject to change depending on
species of concern. Should a fish be able to swim up a barrier apron, the shallow apron
depth eliminates the necessary hydraulic conditions that allow fish to jump over
impediments. To attain proper hydraulic conditions a sill height of 3.5 feet and an apron
length of 15 feet were recommended. The water velocities, depths, and barrier dimensions
reported in this paper were considered general criteria; site-specific deviations were
acknowledged.

BIOLOGICAL EFFECTS OF TAILRACE BARRIER:

The main purpose of these two barrier designs was to allow upstream migrants to find
entrances to fishways located at dams or hatcheries. Therefore, the two types of barrier
dams should reduce migration delays by facilitating fish passage. Also, these barriers, by
design, would prevent fish from swimming into draft tubes and contacting walls and turbine
runners. Proper placement of the barrier dams and fishway entrances was considered
important for reducing attempts by fish to pass the barriers, subsequently reducing chances
for injury.

TAILRACE BARRIER EFFECTS ON PROJECT OPERATION:

The effects of either of these fish barriers on project operations was not discussed. Negative
impacts on power generation may result from increased tailwater levels if sited in proximity
to the tailrace discharge.

COMMENTS:

This paper provides important design criteria, both physical and biological, for two fish
barrier designs. Several sites where these barriers have been successfully installed were used
as examples to demonstrate modifications that may be necessary to prevent fish from passing
upstream and effectively guiding them to a fishway entrance.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 97


units may attract upstream migrants to a
fishway entrance.

Spillways with adjustable gates or
those that can be fitted with non-overflow
sections, can also be operated to attract
fish to a fishway entrance.  Spillway
operation often can be used to improve
fish passage in a bypassed reach of river.

Modified project operation can
have negative impact on generation
capacity and project revenue. But
innovative project designs, as illustrated by
experience at the Wilder Project where
the addition of a small hydro turbine
supplied fishway attraction water, can have
positive economic benefits.

Little cost information is available
for general comparison of barriers because
site-specific conditions generally determine
feasibility and costs of these devices.
Physical barriers typically require extensive
civil works, and tailrace civil conditions
and costs vary greatly. Costs may also be
incurred to provide passage of
downstream migrants around the tailrace
barrier. Generally, behavioral barriers are
the least costly, while barrier screens
would be the most costly alternative
because of cleaning requirements. Barrier
dams and some screen designs also may
reduce usable head and thus reduce
energy and revenue.

4.0 DISCUSSION

The level of mitigation required to
minimize impacts to upstream fish
migrations is determined by a project’s
biological, hydraulic, and physical
characteristics. Some species suffer more

from delays than others because they
spawn under a narrow range of
environmental conditions and within a
short time period. Migration delays,
injury, and mortality associated with
powerhouse operation may have more
adverse impacts to fish stocks and
populations that are at very low levels.

To provide additional information
for assessing the need for tailrace barriers
and modified project operation and spill,
a survey of existing projects was conducted
(see Section 2). The information obtained
through the literature search was used
with survey information to develop criteria
and guidelines for assessing the need for
tailrace barriers and modified project
operation and spill. | Recommended
studies that would provide additional
information on the impacts of
hydroelectric tailraces on upstream
migration also are discussed.

4.1 Summary of Current and Potential
Applications of Upstream Fish
Migration Protection Technologies

As described in Section 2, a survey
of hydroelectric projects where tailrace
barriers are operating, are proposed, or
have been requested by resource agencies
was conducted.

Table 4-1 summarizes the
information collected. Of the 24
identified projects, 8 currently have
upstream migrant protection in the form
of diffuser barriers such as bar racks,
netting, screens, or guidance devices.
There is very little information on
effectiveness of these barriers. At Morse
Creek, Washington, plastic netting

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 33


Annotated Bibliography

Beiningen, K.T., and WJ. Ebel. 1970. Effect of John Day Dam on dissolved nitrogen
concentrations and salmon in the Columbia River, 1968. Transactions of the American
Fisheries Society. 1970. No. 4. pp 664-671.

PACIFIC SALMON
STEELHEAD TROUT
MIGRATION DELAYS

LOCATION OF STUDY:
John Day Dam, Columbia River, Washington.
E RIS'

There was no specific information describing the John Day Project. Construction of the
dam was completed just before initiation of the study, however, the powerhouse was not
operating at this time.

ICAL CHARA RI

The Columbia River supports populations of five Pacific salmon species, steelhead trout,
white and green sturgeon, lamprey, and American shad, all of which migrate annually
upstream to spawning areas.

ECT E IN_UPS' FISH SAGE:
Columbia River hydroelectric projects are impediments to upstream migrants.
Consequently, upstream fish passage facilities have been installed at most of the projects.

This paper describes the effects of gas supersaturation on the Columbia River salmonid
populations. Secondary problems (e.g., migration delays) also are discussed.

TAILRACE BARRIER DESIGN: N/A
BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A
TAIL BARRIE) E IN_PROJECT OPE N: N/A

Page 58 Impacts of Hydroelectric Plant Tailraces on Fish Passage


3.2.2 Modified Project Operation and
ill to Re Tailrace I

Powerhouse operations often can
be modified to reduce attraction of
migrants to draft tube discharges. This
may improve the ability of fish to locate a
fishway entrance or bypass reach and
eliminate potential injury and mortality at
the powerhouse. Modification of spill
regimes (e.g. amount of flow and
distribution) also can help migrants find
fishways or bypass reaches. Attractive
upstream passage routes can reduce
powerhouse-related injury and mortality by
limiting the time fish spend in the tailrace.

Modified project operation can
alleviate injury, mortality, and migration
delays in several ways. Migrants often are
most susceptible to powerhouse-related
damage during turbine start-up and shut-
down when draft tube discharge velocities
are considerably lower than during full or
partial load operations. Since many
migratory species have diurnal (within a
24-hour cycle) movement patterns, injury
and mortality may be reduced if start-ups
and shut-downs are scheduled during low
fish activity. Fish may still enter draft
tubes and be injured or killed, however,
when units are operating with partial
loads. Adverse impacts may be reduced or
eliminated if units are shut off or run at
full load. Injury and mortality that occurs
at full load operation may necessitate
shut-down of problem units. Shut-downs
during all or part of migration seasons
have been somewhat successful at several
projects (Department of Fisheries, Canada
1958; IPSFC 1976; Fedorenko 1989).

Alterations in powerhouse
operations can eliminate migrant
attraction to draft tubes. Clay (1961)
described several scenarios for operating
powerhouse units and for controlling spill
distributions to improve upstream passage.
At large powerhouses, a flume with
multiple entrances leading to a fishway
can be constructed across the face of the
powerhouse above the draft tube exits.
One solution for reducing fishway
entrance problems associated with false
attraction is to keep all units off line
during the entire migration period or
during peak movements each day.

Spill regimes also can be modified
at some sites where fishway entrances
compete with spillway flow (Clay 1961).
At sites with fish ladders on both river
banks, spill can be concentrated in the
middle of the spillway. At sites with one
fishway, spill should be greatest away from
the fishway entrance and decrease closer
to the fishway. This spill regime controls
hydraulics to lead fish to the fishway
entrance and assumes that high velocities
near the spillway exceed the swimming
capacity of fish. At many projects that do
not have some type of adjustable spill -
gates, it may be impossible to control flow
distribution across the spillway. At these
sites, multiple fishways (located at both
ends and in the middle of the spillway)
may be the only means to reduce
migration delays and false attraction. If
the spill amount can be controlled, the
ideal situation may be no spill at all.
Without spill, fishway attraction water
would be the only flow source available
for migrants to follow. However, if
spillway flows are required to maintain
habitat quality downstream of the dam or

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 29


Annotated Bibliography

or killed from striking concrete walls or contact with the turbine runner blades.
Documented internal injuries were attributed to hydraulic shear within the draft tubes.

B, JER DESIGN:

No physical tailrace barriers were installed or proposed at the Seton powerhouse to direct
fish away from the tailrace or to prevent fish from entering the draft tubes. However, to
reduce injury and mortality associated with the draft tubes, the turbines were only operated
at full load. The discharge flow velocities physically prevented fish from entering the draft
tube. Pressurized air was injected into the draft tubes during start-up and shut-down of
turbines to prevent fish entry during these times. Although full power generation reduced
the potential for fish injury and mortality at the powerhouse, fish continued to be attracted
to the discharge and delayed in their migration.

BIOLOGICAL EFFECTS OF TAILRACE BARRIER:

Fish injury and mortality were reduced by operating the station at full generating capacity
during the spawning migration, but false attraction was not reduced.

TAILRACE BARRIER EFFECTS ON PROJECT OPERATION:

Lost generation and revenues could be expected during the upstream fish migrations if flows
dropped below levels that prevented the station from operating at full load.

COMMENTS:

This paper reviewed the history of fisheries-related problems associated with hydropower
development in the Seton area of the Fraser River, specifically focusing on the problems
related to the operation and design of the Seton hydroelectric facilities. Evidence was
provided that adult sockeye and pink salmon were being delayed at the Seton powerhouse
and injured or killed in the draft tubes. Negative impacts from migration delays could not
be documented; however, there were indications that delays could reduce the number of fish
that survive to spawning time.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 61


Annotated Bibliography

Weaver, C. R. 1963. Influence of water velocity upon orientation and performance of adult
migrating salmonids. Fishery Bulletin 63(1):97-121.

COHO SALMON

CHINOOK SALMON
STEELHEAD TROUT
SWIMMING SPEED

ATTRACTION FLOWS !

LOCATION OF STUDY:

Fisheries Engineering Research Laboratory at the Bonneville Dam, Columbia River,
Washington.

PROJECT CHARACTERISTICS: N/A

BIOLOGICAL CHARACTERISTICS: N/A

PROJECT EFFECTS ON UPSTREAM FISH PASSAGE: N/A
TAILRACE BARRIER DESIGN: N/A

BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A
TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A
COMMENTS:

This study examined the swimming capabilities of chinook and coho salmon and steelhead
trout in a laboratory setting. The results support the false attraction phenomenon observed
at many hydroelectric projects and provide a basis for fish ladder design and siting. The
purpose of the study was to determine (1) how adult salmonids respond to differences in
water velocities, (2) adult salmonid swimming capabilities in two relatively high-velocity
flows, and (3) how flow velocity influences rate of movement. When presented with two
different flow velocities in parallel channels, fish of each species typically selected the faster
water velocity. Steelhead trout and chinook salmon swimming performance were assessed
at water velocities of 13.4 and 15.8 fps in an 85-ft channel. During these tests, steelhead
trout demonstrated an ability to swim greater distances against both flow velocities, and
larger fish of both species typically swam greater distances than smaller fish. Both species
negotiated the lower velocity (13.4 fps) more readily than the higher velocity (15.8 fps).

Page 98 Impacts of Hydroelectric Plant Tailraces on Fish Passage


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Annotated Bibliography

IN TRE. AGE:

The Turners Falls Project is an impediment to upstream migrants; however, the installation
of three fish ladders has alleviated the inability of fish to reach upstream spawning grounds.
This study examined the delay of adult shad in the power canal. Apparently, adult shad that
entered the power canal through the powerhouse ladder were having difficulty finding the
entrance to the gatehouse ladder and subsequently continuing their upstream migration.

TAILRACE BARRIER DESIGN: N/A

BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A
TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A
COMMENTS:

The purpose of this study was to examine the movements of upstream-migrating adult
American shad in the power canal of the Turners Falls Project. Shad upstream migrants
were having difficulty locating the gatehouse fish ladder and were remaining in the canal
rather than continuing their migration to upstream spawning areas. The Turners Falls study
comprised two parts. First, radio-telemetry techniques were used to determine shad
movements through the power canal, and second, hydroacoustics were used to locate areas
in the canal where fish may have been accumulating rather than proceeding upstream.

During the radio-telemetry study, nine of ten tagged shad migrated from the powerhouse
fish ladder exit to the head of the canal. Of these nine fish, only one passed through the
gatehouse fish ladder and into the impoundment. Fish that did not enter the gatehouse fish
ladder maintained position downstream of the gatehouse ladder entrance gallery. An eddy
was observed immediately downstream of the entrance and was cited as potentially
inhibiting shad passage. The hydroacoustic study determined that adult shad were
congregating along the canal edges. It was concluded from the results of both studies that
shad were able to ascend the canal but were reluctant to enter the gatehouse fish ladder due
to inadequate attraction flows or entrance configuration.

This study clearly demonstrated the inability or unwillingness of upstream migrants to enter
the fish ladder. The inefficiency of the Turners Falls gatehouse fish ladder delayed
upstream migrants. Effects of the delay on spawning success cannot be determined from
this study; however, it is likely that many adults would not reach upstream spawning areas
before environmental conditions (specifically temperature) would prevent any further
upstream movement and spawning would commence. Because fishery agency management
goals included spawning of American shad throughout their entire range, the delay at
Turners Falls was hampering restoration efforts.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 81


they have on fish. Direct effects include
diversion into areas where fish may be
injured or killed, such as draft tubes and
plunge pools (where they may be
adversely affected by altered river
temperatures or gas supersaturation).
Indirect effects include decreased fitness
leading to lowered reproductive success
and less subsequent recruitment into the
population.

Data also were collected on the
types of tailrace barriers that are currently
used to reduce injury to fish and/or delays
in migration. Studies were reviewed and
summarized to develop the database and
to formulate guidelines and criteria for
modifying project operation or spill
regimes to mitigate impacts.

The literature search included: 1)
a computer search of the open literature,
and 2) a telephone survey of selected
fishery agencies to identify pertinent
reports and data not readily available
through published literature. Agencies
contacted include the National Marine
Fisheries Service (NMFS), U.S. Fish and
Wildlife Service (FWS), fishery agencies in
those states where tailrace barriers are
installed, the Canadian Department of
Fisheries and Oceans (CDFO), and other
fishery agencies identified through
published literature.

A total of 55 studies were identified
and reviewed for this report. Most
available information on tailraces is
included in literature on fish passage
facilities. Tailraces generally have been
studied as part of studies to determine the
best location for fish ladders or bypass
entrances. Much of the literature,

therefore, considers tailraces as a
secondary issue.

In addition to the literature search,
data were gathered from a survey of
hydroelectric projects with known tailrace
problems or at which FERC or state
agencies have required installation of
tailrace barriers. Hydroelectric projects
where tailrace barriers are installed and
operating also were surveyed to determine
barrier effectiveness and costs.

A preliminary list of projects was
compiled and reviewed by FERC to verify
addresses of contacts to determine if each
project was currently licensed or being
considered for relicensing or a new
license. License applications for several
projects identified during the telephone
survey were dismissed before development
of tailrace barrier plans. The contacts for
the remaining projects received a tailrace
barrier survey questionnaire, which
requested information on:

1) site conditions;

2) effectiveness of existing
tailrace barrier designs in
reducing fish injury,
mortality, or delay in
migration; and

3) the cost of these devices.

After 29 survey questionnaires were
mailed, follow-up telephone calls were
made to those parties that failed to
respond to the questionnaire. Information
was received for a total of 24 sites. Data
gathered from the literature review and

Page 2

Impacts of Hydroelectric Plant Tailraces on Fish Passage


Acknowledgments

The Office of Hydropower Licensing, Federal Energy Regulatory Commission
(FERC), thanks John Downing, Elaine Bazarian, and Steve Amaral from Stone & Webster
Environmental Technology & Services for their contributions to this publication. We also
offer sincere appreciation to the members of the Tailrace Review Team including Ken Bates
(Washington Department of Fish and Wildlife), Paul Higgins (BC Hydro), Steve Rainey
(National Marine Fisheries Service), Ben Rizzo (U.S. Fish and Wildlife Service), and Gary
Whelan (Michigan Department of Natural Resources). The technical contributions from
each of these experts were invaluable when completing the final report.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page iti


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Annotated Bibliography

Department of Fisheries, Canada. 1958. The fisheries problems associated with the power
development of the Puntledge River, Vancouver Island, B.C. 40 pages and 9 appendices.

0. .

PACIFIC SALMON
DRAFT TUBE INJURIES

MIGRATION DELAY
MODIFIED OPERATION
TAILRACE SCREENS

ATION OF DY:
Puntledge Hydroelectric Project, Puntledge River, Vancouver Island, British Columbia.

PROJECT CHARACTERISTICS:

At the time of this study (1955-1958) the Puntledge Project consisted of a dam at the outlet
of Comax Lake (about 9 miles upstream from the river mouth), a diversion dam 2.5 miles
downstream from the lake, and an intake and transport pipe carrying water 0.5 mile
downstream to a powerhouse.

BIOLOGICAL CHARACTERISTICS:

Adult Pacific salmon (chinook, coho, pink, chum, and sockeye) and steelhead trout migrate
upstream in the Puntledge River from May through December. Timing of spawning
migrations varies among the six species; chinook salmon are the first to enter the river each
year (late May) and sockeye salmon the last (late October).

PROJECT EFFE ON UPSTREAM FISH PASSAGE:

This study concludes that adult salmon were delayed, injured, and killed at the Puntledge
powerhouse tailrace. Fifty percent of adult migrants, recovered dead and unspawned after
passing through a counting fence upstream of the powerhouse, had severe head and dorsal
injuries. The injuries were attributed to fish striking concrete in or near draft tube exits.
Large numbers of upstream migrants were attracted to the tailrace and attempted to swim
up the draft tubes.

TAILRACE BARRIER DESIGN:

Two methods were evaluated for reducing the number of fish approaching the powerhouse
and entering the draft tubes. In 1955, experiments were conducted with modified power-
house operations and diversion dam releases that included shutdowns and artificial freshets.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 67


Annotated Bibliography

tailrace. Draft tube air injection also was assessed as a means to counter the leakage flow
into the tailrace, as well as to prevent draft tube related injury and mortality.

ICA FE F TAIL! BARRIER:

Migration delays due to false attraction and injury and mortality from turbine runner contact
have been acknowledged as the major contributors to sockeye losses in Seton Creek.
Migration delays were observed even when the spill at the diversion dam was increased to
4,000 cfs. Based on observations of 4,000 cfs flows, it was concluded that 1,000 cfs would
not adequately counteract the attraction of fish to the tailrace and would not alleviate the
fish injury problem.

TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A
COMMENTS:

This study evaluated migration delay mitigation measures and concluded the problem was
reduced with the measures implemented (i.e., plant shut-downs). Impacts to the sockeye
fishery were identified, and attempts were made to alleviate spawning migration delays,
injury, and mortality. However, migration impacts were not completely eliminated, and
other concepts were suggested. Alternative methods for reducing sockeye population losses
included artificial scent attraction, implementation of a physical or electrical barrier, utilizing
a trap and transport system, re-routing the water, and eliminating the tailrace by extending
the draft tube.

Page 76 Impacts of Hydroelectric Plant Tailraces on Fish Passage


IMPACTS OF HYDROELECTRIC PLANT TAILRACES
ON FISH PASSAGE

A Report on Effects of Tailraces on Migratory Fish and Use
of Barriers, Modified Project Operations, and Spills for
Reducing Impacts

Federal Energy Regulatory Commission
Office of Hydropower Licensing
Washington, DC

Paper No. DPR-9

June 1995





(this page intentionally left blank)



A porous dam is more suitable as a
downstream reregulating dam or as a
block to passage into the bypassed reach
of river than as a draft tube barrier
because head loss is generally high.

Buttress-type barrier dams (Figure
3-6) are designed to prevent movement of
fish into bypassed reaches and spillways,
while simultaneously providing flows that
attract fish away from tailraces and
towards fishway entrances.

Typically, this type of dam is
constructed below a spillway to block
upstream fish movement, but above a
tailrace so not to reduce effective project
head. Although a buttress-barrier does
not directly block entry of fish into draft
tubes, it can be used in conjunction with a
fishway to make fishway entrance flows
more attractive than tailrace flows to
migrating fish.

A channel is constructed under the
crest of the dam overflow and connected
to a fishway entrance to facilitate
upstream passage away from tailrace
flows. Fish attempting to jump the barrier
either fall or swim into the channel
beneath the overflow crest; if the barrier
is angled, a lower elevation at the
downstream end will provide an attractive,
direct flow through the channel for fish to
follow to the fishway entrance.

Fishway entrance flows, combined
with flow through the channel beneath the
dam, provide a stronger attraction flow for
fish than do tailrace flows.

Recommended hydraulic head
levels for buttress-type barriers are not

less than 10 feet for salmonids (Wagner
1967; NMFS 1993). To ensure effective-
ness, this type of barrier must be designed
to operate at all possible combinations of
head- and tailwater levels when fish are
migrating.

Velocity barriers (Figure 3-7)
create either water velocities that are
greater than the swimming speeds of a
target species or a plunging flow where
fish cannot turn to jump. Spill or tailrace
discharges descend over a sill at shallow
depths and most typically over a concrete
apron. High velocity flow is produced
across the apron. Generally, fish are
unable to ascend the spilling water at the
end of the apron (Wagner 1967). If fish
do swim or jump on to a velocity barrier
apron, the hydraulic conditions at the
upstream portion of the apron are not
suitable for fish to leap or swim over the
sill (ie., flow is too fast and shallow).
Low tailwater levels may cause fish to
jump at the dam and may lead to injury.
Apron depth on a velocity barrier should
not exceed 6 inches for salmonids
(Wagner 1967; NMFS 1993). The water
velocity necessary to block upstream fish
movement depends on the swimming
capabilities of all species that are targeted
for protection or guidance at a site.
Minimum water velocities of 18, 22, and
26 fps have been recommended for coho
salmon, chinook salmon, and steelhead
trout, respectively.

Wagner (1967) provides general
criteria for salmonid velocity barriers.
Criteria include maximum water depth of
6 inches with a minimum velocity of 16 fps
on an apron at least 15 feet in horizontal
length. A water velocity of 16 fps would

Page 24

Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

injury and mortality (depending on the type of operating modification employed). Improved
fish ladder designs would provide the proper hydraulic conditions that are necessary for
attracting migrants to entrances.

TAILRA( RATION:

Modifications to spill and turbine operations may effect generating capabilities, and
revenues may be lost. Improved fish ladder designs would not impact project operation
unless the improvements involved increasing attraction water flows or the ladder used
greater volumes of water.

COMMENTS:

This paper provides a brief overview of impacts of hydropower development on the
Columbia River on the anadromous fish population. Hydropower projects were cited as
sources of fish mortality and migration delays. Mortality at some dams was positively
correlated with flows. One possible source of mortality at dams was abrasion injuries
(specifically observed for chinook salmon). Modified flow regimes throughout the river
basin were believed to contribute to delays in migration. Delays may have been more
significant during high flow periods because increased spill and turbine discharge can mask
fishway attraction flows. In the Snake River, a thermal block was thought to delay upstream
migrants and may have contributed to mortality of adult chinook salmon and steelhead
trout.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 83


Annotated Bibliography

upwelling flow at which fish are less likely to jump. A horizontal diffuser is entirely
submerged even at low tailwater elevations.

The paper describes several types of variable-slope weirs that are designed to exclude fish
whereas floating debris can pass through. Variable-slope weirs typically comprise smaller
diffuser panels compared to vertical or horizontal barrier racks. The panels are placed side
by side across the entire stream width and are connected by hinges to concrete sills or apron
structures located on the river bottom. The entire diffuser inclines downstream. The hinges
allow variable-slope diffusers to adjust to flow levels and to pass large debris. Floating,
hydraulic diffuser, and pneumatic weirs are three types of variable-slope designs. Floating
weirs have planer boards on the downstream side of the panels to provide uplift. As debris
loads increase, the uplift is overcome and debris passes downstream. Hydraulic diffuser
weirs use hydraulic cylinders to control the position of weir sections. Pneumatic weirs
incorporate an air filled bladder downstream of the panels at the base of the structure. The
inflation level of the bladder determines the angle of the weir.

Non-diffuser barriers include hydraulic and behavioral barriers. Hydraulic barriers are
designed to impede fish passage by creating impassable static head or water velocities.
Hydraulic barriers typically are concrete structures that either create static head in excess
of 10 feet or high water velocities over a sloped apron. Behavioral barriers (e.g., electrical,
sound, or light systems) are used to elicit an avoidance response from fish. Electrical
barriers have been developed for tailrace applications and rely on fish to avoid the electrical
field or become temporarily impaired causing the fish to be swept downstream. The
electrical field is designed to decrease in strength from the upstream to downstream
direction; this results in fish becoming more paralyzed by the electrical current as they
attempt to swim upstream. Although extensive research has been conducted with alternative
behavioral devices, such as various types of sound and lights, for fish protection, most of this
work focuses on downstream migrants.

Operational changes can be implemented to alleviate migration delays and prevent turbine-
related injuries and mortality. Partial or full plant shut down for designated time periods
may inhibit fish from-entering a tailrace or cause fish already present to leave and seek
alternative passageways (e.g., fish ladders). Full load operation may exclude fish from draft
tubes by creating impassable water velocities reducing related injuries and mortality. The
manner in which turbines are brought on and off line also may influence occurrences of fish
injury and mortality. Sudden increases or decreases in flow may trigger fish to enter draft
tubes; lower water velocities prior to full generation or turbine stoppage will allow fish to
enter draft tubes. Spill modifications also can influence the passage route chosen by
approaching upstream migrants. Increased spill may draw fish away from tailrace entrances
and towards spillway fishways.

Page 78 Impacts of Hydroelectric Plant Tailraces on Fish Passage


openings are created by splitter walls or
flow training vanes. Projects with these
types of draft tube structures can have
complex hydraulics and may have high
hydraulic shear zones that can injure fish.
Some of the multiple draft tube openings
may experience reverse flows; tailrace
water enters one draft tube opening and
exits via another. In these cases any
downstream fish may be drawn into the
draft tube and be injured by hydraulic
shear.

Fish may be injured or killed by
turbine contact at projects with vertical-
shaft Francis units (Bengeyfield 1982),
reaction turbines (Fedorenko 1989), and
axial flow-tube turbines (Williams 1985).
Fish may not be able to contact Pelton
turbine runners since they usually are
located above draft tube water levels
(Schadt et al. 1985; Beak Consultants, Inc.
1993). Fish also may contact Kaplan
turbine runner blades, and protective
measures have been requested by resource
agencies at some hydroelectric sites with
this type of turbine.

Although fish may be able to
physically ascend a draft tube, other
factors may prevent them from reaching a
station’s turbines. At the Jackson
Hydroelectric Project on the Sultan River
in Washington, adult salmonids do not
contact the two Pelton turbines because
the runners are about 11.5 feet above the
tailwater elevation during periods of
average flows (actual distance depends on
discharge flows and tailwater elevation;
Schadt et al. 1985). In addition to unit
location, high water velocities (actual
measurements were not reported),
considerable turbulence, air depression

system noise, and lack of a tailrace pool
prevented fish from contacting the turbine
runners (Schadt et al. 1985).

Fish also may be injured or killed
by contact with draft tube walls caused by
high water velocities and turbulence. Fish
ascending draft tubes can be thrown
against concrete walls and/or contact
turbine blades and runners. Injuries also
have been attributed to hydraulic shear
within a draft tube (Bengeyfield 1982).
Fish also may be injured by attempting to
"jump" at powerhouses. Injuries, which are
usually sustained from striking rock or
structural projections, often result in direct
or delayed mortality (NMFS 1993).

Injury Type

The types of injury sustained by
some fish entering draft tubes or
contacting turbines vary from site to site,
as do immediate and delayed mortality
rates. Several studies, however, attribute
injuries in migrating salmonids to
powerhouse structures associated with
tailrace areas (Department of Fisheries,
Canada 1958; IPSFC 1976; Marshall 1973;
Schadt et al. 1985; Williams 1985;
PacifiCorp 1993).

At the Puntledge Hydroelectric
Project, dead adult salmon recovered
upstream from the powerhouse had severe
head and dorsal injuries (Department of
Fisheries, Canada 1958). Although there
was no direct evidence, injuries were
attributed to fish swimming into the draft
tubes and subsequently striking concrete
walls and/or turbine runners. Reports
subsequent to the 1958 study also identify
fish injury (particularly head injury) and

Page 6

Impacts of Hydroelectric Plant Tailraces on Fish Passage


6.0 LITERATURE CITED

Barwick, D. H., and L. E. Miller. 1990. Effectiveness of an Electrical Barrier in Blocking
Fish Movements. Duke Power Company Production Environmental Services,
Huntersville, NC.

Bates, K. M. 1992. Fishway Design Guidelines for Pacific Salmon. Washington
Department of Fish and Wildlife. Working Paper 1.4. 82 pp and Appendix.

Beak Consultants, Inc. 1993. A Study to Determine the Influence of the Snoqualmie Falls
Project on the Injury or Mortality of Adult Salmonids. Beak Consultants Inc. June
1993. Prepared for Puget Sound Power & Light Company, 31 pp.

Beiningen, K. T., and W. J. Ebel. 1970. Effect of John Day Dam on Dissolved Nitrogen
Concentrations and Salmon in the Columbia River, 1968. Transactions of the
American Fisheries Society, 99 pp 664-671.

Bell, M. C. 1990. Fisheries Handbook of Engineering Requirements and Biological
Criteria. Fish Passage Development and Evaluation Program, Corp of Engineers,
North Pacific Division, Portland, OR.

Bengeyfield, B. 1982. Review of Fisheries Enhancement Programs in Seton Lake - Cayoosh
Creek area. Prepared for British Columbia Hydro and Power Authority, Reservoir
Land Management Department, Properties Division. Prepared by Environmental
Sciences Ltd, 19 pp.

Brown, B. J. 1994. Draft Report Comment Letter to J. Downing. July 27, 1994. National
Marine Fisheries Service, Portland, OR. 7 pages.

Brown, R. L. 1991. Bioengineering Problems in River Systems of the Central Valley,
California. American Fisheries Society Symposium, 10 pp 19-31.

Bry, C. 1981. Temporal Aspects of Macroscopic Changes in Rainbow Trout (Salmo
gairdneri) Oocytes Before Ovulation and of Ova Fertility During the Post-Ovulation
Period; Effect of Treatment with 17 Alpha-Hydroxy-20 Beta-Dihydroprogesterone.
Aquaculture 24: 153-160.

Bulow, F. J., M. A. Webb, W. D. Crumby, and S. S. Quisenberry. 1988. Effectiveness of
a Fish Barrier Dam in Limiting Movement of Rough Fishes from a Reservoir into
a Tributary Stream. North American Journal of Fisheries Management, Vol. 8 pp
273-275.

Page 48 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

Sloane, R. D. 1984. Upstream migration by young pigmented freshwater eels (Anguila
australis australis Richardson) in Tasmania. Australian Journal of Marine and Freshwater
Research 35:61-73.

IS

FRESHWATER EELS
MIGRATION CUES

LOCATION OF STUDY:

Trevallyn and Meadowbank Hydroelectric Projects, the island of Tasmania off the southeast
coast of Australia. Sampling also was conducted on smaller stream barriers throughout
Tasmania.

PROJECT CHARACTERISTICS: N/A
BI ICAL CHARA RISTICS:

Juvenile freshwater eels (elvers) annually migrate upstream to rearing habitats throughout
the river systems of Tasmania.

PROJECT EFFE! IN_ UPSTREAM FISH PASSAGE:

The Trevallyn and Meadowbank projects were an impediment to upstream movements of
elvers. No upstream passage facilities exist at either project or at any of the smaller barriers
that were examined. However, because eels can climb over land and up certain structures
during rain periods, the blockage of elver migrations was not 100 percent at any of the study
sites. At the Trevallyn Project it was determined that turbine output, not environmental
factors, exerted the greatest influence on elver catches. When turbine output was high it
prevented elvers from entering the trap areas in the tailrace because the elvers could not
swim against the flow.

TAILRACE BARRIER DESIGN:

Tailrace barriers were not discussed in this paper. Juvenile eels do not have the swimming
capabilities that are generally required for ascending draft tubes. Because fish were not
trying to reach spawning areas and there were no upstream passage facilities, delayed
migration was not an issue. Elvers remaining in the tailrace incur long-term physiological
costs and population loss if elvers are not able to reach upstream feeding grounds. Trapping
and transport was conducted, however, to stock upstream areas with elvers to improve the
overall eel production of Tasmania’s rivers.

Page 90 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

Doret, S. C. 1987. A fishway that generates power. Hydro Review, October.
Additional Literature:

Millette, A.J. 1989. Wilder fish ladder with a hydroturbine as a fish-attracting water
system. American Fisheries Society Symposium 10:551.

ATTRACTION WATER
ATLANTIC SALMON

LOCATION OF STUDY:
Wilder Hydroelectric Project, Connecticut River, Vermont.
PROJE! HARA‘ ‘RISTICS:

The Wilder Hydroelectric Project was constructed in 1950 with two 17 MW Kaplan turbines
and provisions for a third unit and fish passage facilities. The third unit eventually was
installed and consisted of a 3.2 MW Francis turbine. After the Anadromous Fish
Conservation Act was passed in 1965, a restoration program for Atlantic salmon was
developed for the Connecticut River Basin and subsequently a fish ladder was installed at
the Wilder Project. The design of the third unit allows the Wilder Station to uniquely meet
the needs of fishway attraction water, minimum flow, and power generation simultaneously.
The attraction water for the fishway is provided from exit flows of the third unit which
generates power at the same time. Minimum flow is passed both during fishway operation
and when the other two units are shut-down. A bypass system has been incorporated in the
event of a unit outage during the fish migration season. Construction costs were $7.54
million for the fish ladder and $6.5 million for Unit 3.

RISTICS:

Atlantic salmon are currently being restored to the Connecticut River. Very few fish have
been passed upstream at the Wilder Project because only 10 percent of upstream migrants
are allowed to pass the first dam they encounter after entering the river in the spring (the
remaining 90 percent of adult returns are held for broodstock purposes). Also, the
Testoration program relies entirely on smolt and fry stocking for producing adult returns.
The large majority of fish that are stocked are released downstream of the Wilder Project.

PROJECT EFFECTS ON UPSTREAM FISH PASSAGE: N/A

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 69


to allow fish to move up the river, no spill
would not be a viable solution.

Bell (1990) presents powerhouse
and spillway modifications for improving
upstream passage that are nearly the
opposite of those proposed by Clay (1961),
even though both authors would likely
agree on project-specific fishway and
spillway flows. Bell (1990) states that
spillway flow and turbine discharges
should be greatest near fishway entrances
in order to attract fish to the vicinity of the
entrance. These opposite conclusions are
based on the opposite assumption each
author makes on the effect of spillway
flows. Clay assumes, from experience with
large hydro projects, that spillway flows
create velocity conditions that exclude fish.
Bell assumes spillway flows attract fish in
the high-flow conditions. Bell (1990)
views spillway flows as supplementary
attraction water and suggests that flows
should increase in volume from the
opposite end of a powerhouse or spillway
to the end with the fishway entrance. Bell
(1990) also suggests that flows at spillways
with fishways at either end should be
greatest near the fishway entrances and

* taper off towards the center of the
spillway.

If natal stream scents are the
source of false attraction, altering
powerhouse operation and spill regimes
may not alleviate injury and mortality or
migration delays. At the Seton
Hydroelectric Project on the Fraser River
in British Columbia, the powerhouse was
shut down during the upstream migration
of sockeye and pink salmon runs to reduce
attraction of fish to the draft tubes where
they were being injured and killed (IPSFC

1976). Seton Creek is diverted into a
power canal that leads to the Seton
powerhouse which releases the water into
the Fraser River downstream of its
confluence with Seton Creek. Spill was
increased at the Seton diversion dam to
enhance mainstem river flows and,
consequently, facilitate upstream
migration. Because of wicket gate
leakage, however, fish still ascended the
draft tubes. Continued attraction of fish
was attributed to the scent of Seton Creek
water leaking through the gate. Fish that
followed the leakage into the draft tubes
were susceptible to injury and mortality
during start-up periods. The leakage
problem was reduced by injecting air into
the turbines when they were not operating.

Spillway flows may need to be
increased when the bypass reaches contain
important spawning or rearing habitats
(for resident and migratory species) which
attract migrants despite low-flow levels.
For tailraces leading to a powerhouse
without passage facilities, increased bypass
reach flows may keep fish from entering
the tailrace. Artificial freshets may be
used to stimulate fish movement in a river
channel (Hayes 1953), thus allowing
migrants to reach spillway fishways.
Ramping rates may be necessary when
altering flows to prevent safety hazards to
humans and stranding of fish.

At most projects, powerhouse
operation modifications will reduce
generation revenues if one or more units
cannot be operated at full load. However,
if flow levels necessary for operating all
powerhouse units at full capacity are not
available, there may be no loss of
revenues. Spill reductions to enhance

Page 30

Impacts of Hydroelectric Plant Tailraces on Fish Passage


operation. Appropriate sampling methods
are conventional marking, fin clipping, or
acoustic and radiotagging. Actively
migrating fish are collected, tagged, and
released into the project tailwaters. The
fish entering the fishway are trapped. The
time between release and recapture is
defined as the delay time. With radiotags
and directional antennas, radiotagged fish
movements can be monitored. Fish that
are delayed due to hydraulics or fishway
entrance conditions often can be identified
from such a study.

4.2.2 Hydraulic Studies

Numerical or physical modeling
studies may indicate that the draft tube
can be extended or reshaped to increase
velocities or redistribute flows more
evenly, which could reduce fish injury.
Specific numerical or physical modeling
conducted would depend on the physical
features of the draft tube or tailrace area.
Physical modeling is also very useful in
characterizing conditions under a variety
of spill and operation conditions. Such
studies also should model backwater affect
of such changes since  tailrace
modifications could impact the effective
head and energy of the project.

Hydraulic modeling also may help
identify simple modifications to improve
the hydraulics near fishway entrances.
Studies may be able to identify how
separator walls between the spillway and
powerhouse could eliminate eddies that
mask spillway attraction flows or otherwise
misdirect migrating fish.

43 Guidelines for Evaluating Agency
Requests for Tailrace Barriers

In evaluating requests for tailrace
barriers, FERC staff should consider the
need, feasibility, effectiveness, and cost of
such devices. Although these four
considerations are interrelated, staff
should evaluate each of the four steps
separately. Staff should also consider the
professional opinion of the resource
agencies.

4.3.1 Need

The need for tailrace barriers
should be well documented before FERC
staff pursues further steps. One source of
documentation is a comprehensive fish
management plan for the watershed.
Tailrace barriers will have capital and
operational costs that must be justified by
a defined need. Cases that would pass the
need step include:

1) an established migratory fish
program that would be
adversely affected by
tailrace injury, mortality, or
delay at a specific project;

2) a potential for a recurring,
or large fish kill, high injury
rate, or delay that is a result
of project tailrace
operations;

3) a watershed management
plan or specific fish
restoration plan that cannot
be implemented until a
tailrace barrier can be

Page 42

Impacts of Hydroelectric Plant Tailraces on Fish Passage


. Project generation and
revenue can be influenced
by the head loss associated
with installation and
operation of barrier dams,
bar racks, and screens.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 47


incorporated at a specific
project; or

4) physical or hydraulic tailrace
conditions similar to other
projects that have been
shown to lead to injury,
mortality, or migration delay
to the same species of fish.

Poorly identified needs for tailrace
barriers include:

1) a non-presence of a
migratory fishery, or a
proposed fishery that has a
less than reasonable
restoration plan even with
installation of  tailrace
barriers;

2) a concern for undocu-
mented or poorly docu-
mented injury or delay at a
project tailrace; or

3) use of only hydraulic flow
velocities to show that some
resident fish species may be
able to ascend the draft
tubes of a project.

Poorly identified needs for tailrace
barriers must be clarified before
continuing the need evaluation.
Additional studies (see Section 4.2) to
identify need may be requested of the
licensee or the agency requesting tailrace
barriers. Poorly identified needs for
tailrace barriers may come from watershed
plans or migratory fish restoration plans.
Insufficient data on need for a barrier will
not justify the typical costs of a tailrace

barrier. The need for barriers has been a
contentious issue. If the plans do not
contain enough information to
demonstrate that the fish populations
require tailrace barriers to sustain a viable
population, then additional information
must be obtained to define the need.
Studies may demonstrate that such
barriers are not necessary.

4.3.2 Feasibility

Feasibility of a tailrace barrier
depends on the type of impact to be
mitigated (injury or delay), the biological
characteristics of the species, and the
physical conditions of the tailrace. The
relative importance of these issues, which
is project specific, will determine the
feasibility and selection of the most
appropriate tailrace barrier.

Generally, a change in project
operation should first be investigated to
determine feasibility to prevent injury and
delay. Changes in project operation are
not as likely to require an irrevocable
capital expense and can be tested to
determine their effectiveness, before being
implemented on a permanent basis.

If passage into a bypassed reach of
river leads fish beyond a tailrace ladder
entrance, a barrier dam should be
considered. A barrier dam in the
bypassed reach of river does not
necessarily affect the conventional
operation of the hydro facility.

If injury or delay due to draft tubes
is a problem, bar racks or screens should
be considered. Debris conditions should
be factored into the feasibility assessment

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 43


Annotated Bibliography

of days fish were held. Despite faster migration rates, females with greater levels of
maturation did not travel as far upstream as females with lower levels of maturation.

From the data obtained during this study and evidence from two independent studies (Bry,
1981; Sakai et al., 1975) conducted with rainbow trout (controlled laboratory experiments),
the authors concluded that spawning-run delays of Arctic grayling may reduce egg viability
and result in decreased hatching rates of eggs and increased deformity rates of alevins.
Also, delayed migration may lead to fish spawning in unsuitable habitats because they were
unable to reach upstream spawning areas within time periods constrained by biological (e.g.,
level of maturation) and physical (e.g., water temperature) parameters. Based on these
factors, it was concluded that spawning-run delays would. reduce recruitment to the
population.

Page 72 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

Rondorf, D. W., G. A. Gray, and W. R. Nelson. 1983. Effects of hydropower development
on Columbia River salmonids. In: Waterpower °83: International Conference on
Hydropower. Volume III: Environmental Impacts; Research and Development; Dam Safety;
General Sessions.

| KEYWORDS __
PACIFIC SALMON

MODIFIED OPERATIONS
MIGRATION DELAY
FALSE ATTRACTION

‘ATI DY:
Columbia River Basin.

PROJECT CHARACTERISTICS: N/A

BIOLOGICAL CHARACTERISTICS:

The Columbia River supports populations of five Pacific salmon species and steelhead trout.
ROJECT EFFECTS ON UPS' FISH PASSAGE:

Hydropower development has impacted all anadromous salmonid populations of. the
Columbia River Basin by delaying migrations and contributing to mortality and injury of
upstream and downstream migrants. Depending on the project, impacts may include injury
and mortality of upstream migrants from gas supersaturation, draft tubes, or turbine runners,
Also, migration delays may result from false attraction of fish to spillway areas and tailraces
and alterations in temperature regimes upstream of a project (typically in impoundments).

TAILRACE BARRIER DESIGN:

Physical tailrace barriers are not discussed and modifications to spill and turbine operation
and improved fish ladder designs are briefly mentioned as means that have been employed
to reduce upstream migration delays and injury and mortality.

BIOLOGIC. FFECTS OF TAILRACE BARRIER:
Spill modifications may reduce migration delays by allowing upstream migrants to more

readily locate fish ladder entrances. Modifications to turbine operations also would facilitate
migrants finding fish ladder entrances and would reduce draft tube or turbine runner related

Page 82 Impacts of Hydroelectric Plant Tailraces on Fish Passage


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Impacts of Hydroelectric Plant Tailraces on Fish Passage - A Report on Effects of Tailraces
on Migratory Fish and Use of Barriers, Modified Project Operations, and Spills for
Reducing Impacts

This report summarizes what is known about the impacts of tailrace barrier structures
and operations at hydroelectric plants on injury, mortality, migration, and reproductive
success of fish. Little scientific information exists about these topics. Important tailrace
issues arise at some hydropower developments, however, particularly when tailraces appear
to disrupt migratory behavior patterns of anadromous fish populations.

This report provides background perspective and technical guidance for FERC staff
to use when reviewing hydropower license applications and evaluating resource agency
recommendations about tailrace problems. The purpose of the report is to assist staff in
establishing independent, objective, and sound licensing positions about tailrace barriers.

Eh Queue" Ard Sonny

John H. Clements Fred E. Springer
Director, Division of Project Review Director, Office of Hydropower Licensing

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page i


Annotated Bibliography

Williams, R. 1985. Report on the loss of salmonid fish at the Winchester Hydroelectric
Project in 1984. Oregon Department of Fish and Wildlife, Research and Development
Station.

CHINOOK SALMON

STEELHEAD TROUT
INJURY DRAFT TUBE

LOCATION OF STUDY:

The Winchester Hydroelectric Project, North Umpqua River, Winchester, Oregon.

PROJECT CHARACTERISTICS:

The Winchester Project consists of a powerhouse and dam with a bedrock outcrop
separating the tailrace and spillway areas. A fishway is located adjacent to the powerhouse,
and entrances have been placed in both the tailrace and spillway areas. A detailed
description of the Winchester Project was not provided (i.e., number and types of units,
discharge flow volumes, river flow levels).

[Note: This project was shut down per FERC order on remand rescinding the project’s
Exemption from Licensing. Issued December 17, 1985 - 33 FERC paragraph 61,387.]

BI ICAL

Adult chinook salmon and steelhead trout annually migrate to spawning areas upstream of
the Winchester Project.

PROJECT EFFECTS ON UPSTREAM FISH PASSAGE:

Because the original Winchester Dam was an impediment to upstream fish passage, the
existing fish ladder was upgraded when the powerhouse was installed. Injury and mortality
associated with fish entering the station draft tubes were identified during the study. Injuries
included broken vertebrae and internal bleeding immediately posterior to the head.
Migration delays were not discussed; however, attraction to the tailrace discharge indicates
delays may exist. It was assumed that the greater the flow going through the powerhouse
the greater the attraction of upstream migrants to the tailrace. This was most evident at
higher flow levels when the proportion of the total river flow diverted through the
powerhouse was greatest.

Page 100 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

Bengeyfield, B. 1982. Review of fisheries enhancement programs in Seton Lake - Cayoosh
Creek area. Prepared for British Columbia Hydro and Power Authority, Reservoir Land
Management Department, Properties Division, Vancouver, B.C. Prepared by Environmental
Sciences Ltd. Vancouver, B.C.

FALSE ATTRACTION
SOCKEYE/PINK SALMON
| MIGRATION DELAY

: DRAFT TUBE INJURY

LOCATION OF STUDY:

Seton Hydroelectric Project, Seton Creek, Lillooet, British Columbia.

TERIS' :

The Seton Project consists of a dam on Seton Creek, a power canal, and a powerhouse that
is located on the Fraser River downstream of the Seton Creek confluence. The dam diverts
water from Seton Creek through the power canal which carries it to the powerhouse. At
the powerhouse, water is discharged into the Fraser River. (Note: no information on flow
volumes or powerhouse design was provided.)

BIOLOGICAL CHARACTERISTICS:

The Fraser River system supports runs of sockeye, pink, coho, and chinook salmon. The
sockeye population is the most important salmonid that returns annually to Seton Creek to
spawn. Sockeye spawn above and below the Seton Dam. Pink salmon also return to Seton
Creek each year, but in lower numbers than sockeye.

ROJECT EFFECTS ON STREAM FISH PASSAGE:

Upstream migrants returning to Seton Creek have been delayed at the Seton powerhouse
because it discharges large volumes of Seton Creek water into the Fraser River downstream
of the natural confluence. The natural outlet discharges less water than the powerhouse.
Upstream migrants detect the water from their natal stream at the powerhouse and
consequently attempt to ascend the tailrace. Greater water velocities coming from the
powerhouse also induce false attraction for adult salmon. Also, fish that did migrate past
the powerhouse often had difficulty detecting the natural channel of Seton Creek because
the concentration of water from another stream that discharged into it below the dam was
much greater due to lower Seton Creek flows that resulted from power generation. Fish
that did enter the powerhouse tailrace were able to enter the draft tubes and were injured

Page 60 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Secondary infection of fish
with contact-type injury can
lead to delayed mortality
and lowered reproductive
success.

Cai f Del:

.

Stream scents and hydraulic
conditions can attract
upstream migrants to
impassable tailrace flow
discharges.

Inadequate fishway location,
numbers, or entrance
conditions also can delay
passage.

Tailrace Barriers

Few data are available on
the effectiveness of tailrace
barriers at existing
hydroelectric facilities.

A survey of sites with
tailrace barriers shows 22
sites currently have bar
racks, screens, netting, or
other guidance devices for
upstream migrants.

Tailrace barriers can be
used to repel migrants from
undesirable passage routes
and guide fish to ladders or
other preferred routes of
migration.

Diffuser barriers provide a
physical block to migrants

without inducing fish to
jump at the structure.

Height and water velocity
block or guide fish passage
at barrier dams.

Graduated electric fields
have been successfully used
to block upstream passage.

Sound- or __ light-based
behavior barriers have
potential for providing
alternative methods in
blocking fish passage but
generally require more
documentation of
effectiveness.

Modified project operation
and spill releases have been
used to limit delay and
improve passage conditions.

Guidance for Reviewing Tailrace
Barrier Recommendations

Guidance for  tailrace
barriers is a four step
evaluation of need,
feasibility, effectiveness, and
cost.

Biological or hydrological
studies often can provide
the information needed for
completing the four-step
evaluation for  tailrace
barriers at a project.

Page 46

Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

1980s, however, concluded that the diversion dam was a major impediment to the upstream
migration of salmonids, contributing to considerable migration delays and blockage.

TAILRACE BARRIER DESIGN: N/A
BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A
TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A

MME-

This paper did not examine the use of tailrace barriers, but it did summarize studies that
have been conducted at the Red Bluff Diversion Dam that have identified considerable
migration delays at the dam’s two fishways. Biological effects of migration delays that were
identified included increased pre-spawning mortality, reduced egg viability, and fish
spawning below the dam where high water temperatures may be lethal to eggs. During
experiments conducted at Red Bluff, spillway crest gates were manipulated to produce
various flow conditions in attempts to attract fish to the two fish ladders. It was concluded
from these experiments that the fish ladders had insufficient flows and inadequate entrance
configurations. Based on these results, replacement or modification of the fish ladders was
recommended to provide increased flows at the entrances. Placement of entrances at a
depth that would increase the probability of upstream migrants locating them also was
recommended.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 95


WEIR PICKETS
WATER ELEVATION —\

FLOW
> <¢——— FLOW LIFT
BOARD

HINGED SUPPORT ee

~~ ===

FIGURE 3-3
FLOATING WEIR

TAILRACE BARRIER STUDY
SOURCE: MODIFIED FROM MWFS 1999

Page 20 Impacts of Hydroelectric Plant Tailraces on Fish Passage


3.2.1 Tailrace Barriers

Tailrace barriers prevent entry of
fish into tailrace areas or turbine draft
tubes or guide migrants to a fishway or
bypass reach. Tailrace barriers may be
physical structures, behavioral barriers, or
electrical barriers. Physical structures
include various bar racks (or screens) and
barrier dams that create hydraulic head or
water velocities that fish cannot ascend.
Behavioral barriers block fish movement
by eliciting an avoidance response from
them which causes them to retreat or seek
an alternative route. Behavioral barriers
have been extensively evaluated for
blocking or guiding downstream migrants
(EPRI 1986, 1993), but not as much for
upstream migrants. Electrical barriers
have been examined more than any other
available device for upstream passage.

NMFS categorized tailrace barrier
designs as diffuser or non-diffuser (NMFS
1993). Diffuser barriers distribute flow
over a relatively large area and may
reduce attraction of fish and physically
prevent movement of fish into upstream
areas. Diffuser barriers include vertical or
inclined bar racks, horizontal bar racks,
and floating weirs.

Non-diffuser barriers create
impassable physical or hydraulic
conditions or produce a stimulus that
elicits an avoidance response from fish.
Non-diffuser barriers include various types
of barrier dams and behavioral barriers
(e.g., electrical fields, lights, and sound).

Both types of tailrace barriers are
designed to prevent upstream movement
of fish. Any of these barriers can be

operated seasonally. They can also be
used in combinations to overcome unique
conditions of any tailrace. If designed
accordingly, barriers also can be used to
guide fish to alternative passage routes.

Diffuser Barriers

Diffuser barriers (barrier screens or
bar racks) prevent movement of fish into
tailraces or draft tubes and are designed
to guide migrants to a fishway entrance or
bypass channel. Diffuser barriers include
vertical, inclined, and horizontal screens.
Despite design differences, each diffuser
barrier produces a physical block to fish
without inducing fish to swim or jump at
the barrier in attempts to move upstream.

Although diffuser barriers may
alleviate fish injury and mortality, they
may not reduce migration delays unless
they are specifically designed to do so. To
facilitate upstream passage and to block
movement into draft tubes, barrier screens
and racks should be angled with the
upstream terminus located at a fishway or
bypass channel entrance. Regardless of
purpose, a properly designed diffuser
barrier should block upstream movement
of fish in a selected water course without
creating additional injury, mortality, or
delay problems.

Important barrier screen
characteristics include water velocities,
static head levels, and location. The most
important biological factors affecting
barrier screen performance are water
velocities and hydraulic head levels that
do not induce fish to jump at a barrier.
Between-bar spacing (i.e., clear opening)
must be narrow enough to prevent the

Page 16

Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

Rates of fish movement were evaluated at water velocities of 2 to 15.8 fps and over a
distance of 30 feet. Steelhead trout and coho salmon increased their rate of movement as
water velocities increased from 2 to 8 fps, whereas chinook salmon rates of movement
decreased with increases in velocity. There was no indication that the distance fish were
able to swim influenced their rate of movement at water velocities of 13.4 and 15.8 fps.

The results of this study are extremely important to the design of fishways, specifically for
consideration of attraction flows. Upstream-migrating salmonids appear to select faster
water velocities when confronted with two flow magnitudes. The author concluded that
upstream migrants may not locate fishway entrances if there are adjacent flows with greater
velocities. Specifically, the author cited spillway and turbine discharge at Columbia River
low-head dams as competing flows that may prevent fish from locating fishway entrances.
It also was noted that flow volume could have influenced water velocity selection, as it was
greater in the channel with the faster velocity. Furthermore, because this was a controlled
study that manipulated water velocities only, the influence of other factors such as
turbulence, turbidity, temperature, and light intensity could not be determined. These
parameters may vary considerably among fishway locations and could have a significant
effect on the migration routes chosen by adult salmonids at hydroelectric sites. Variations
in the swimming capabilities among the three species also demonstrate the need to assess
upstream migration problems at a hydropower project on a species by species basis.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 99


Electric fields or fences have been
used as fish barriers for many years, but
persistent problems (e.g., fish injury and
mortality, safety, and effectiveness at a
wide range of flows and environmental
conditions) have inhibited widespread
acceptance and use (Clay 1961; NMFS
1993).

Recently, Smith-Root, Inc.,
developed and patented a Graduated
Field Fish Barrier (GFFB) designed to
block upstream fish movement. The
GFFB produces a DC electrical current
with electrodes placed across the channel
bottom (eg. stream or _ tailrace)
perpendicular to the flow. The electrodes
are mounted in an insulating medium
(often a specific type of concrete), evenly
spaced, and designed to produce a
electrical field decreasing in strength from
upstream to downstream. This design
increases field strength as fish approach
the barrier. Fish that do not initially
retreat eventually are overcome by the
electrical current and are involuntarily
swept downstream.

Studies have been conducted to
examine the GFFB’s effectiveness while
minimizing additional injury or mortality
(Rozich 1989; Hilgert et al. 1992). Other
studies focused solely on a GFFB’s ability
to repel fish or prevent upstream
movement (Seelye 1989; Barwick and
Miller 1990). A study at the Quilcene
Hatchery on the Quilcene River in
Washington demonstrated that a GFFB
prevents upstream movement of adult
salmonids without causing injury or
mortality or damaging gametes of
upstream migrants (Hilgert et al. 1992).
However, the GFFB at Quilcene was

ineffective when river flows were high.
Two studies conducted on rivers in
Michigan demonstrated that GFFBs could
effectively block upstream migrations of
sea lampreys (Rozich 1989; Seelye 1989).
One study also showed no apparent injury
or mortality sustained by downstream-
migrating steelhead trout post-spawn
adults and smolts exposed to the GFFB
(Rozich 1989), The GFFB’s also block
migration of non-target species such as
lake sturgeon and adult steelhead (Whelan
1994). In an experimental flume, a GFFB
successfully inhibited movements by
several species of resident freshwater fish
(Barwick and Miller 1990). This study
assessed the fish response to the GFFB
during simulated non-generation,
generation, and pumpback flow regimes.

Although electrical fields like the
GFFB show promise as tailrace barriers,
many state and federal resource agencies
do not consider them a proven technology
(NMFS 1993). Electrical barriers may not
be completely effective at blocking fish
under all conditions. High flows reduce
the effective strength of an electrical field,
and increased field strength to overcome
high flows may increase injury or
mortality. Also, temperature, conductivity,
and fish size influence the effect of
electrical currents on fish. Because the
ability of an electrical current to
immobilize fish depends on fish size,
smaller fish may easily pass through
electrical fields that are designed for
larger fish. Safety to other animals and
humans may be an operational concern.
Monitoring for corrosion and reliable
operation may be maintenance issues.

Page 28

Impacts of Hydroelectric Plant Tailraces on Fish Passage


Rondorf, D. W., G. A. Gray, and W. R. Nelson. 1983. Effects of Hydropower Development
_ on Columbia River Salmonids. In: Waterpower ’83, International Conference on
Hydropower, September 18-21, Knoxville, TN. Vol. III, pp 1201-1212.

Ross, Q. E., D. J. Dunning, R. Thomas, J. K. Menezes, G. W. Tiller, and J. K. Watson.
1993. Response of Alewives to High Frequency Sound at a Power Plant on Lake
Ontario. North American Journal of Fisheries Management Vol. 13, pp 291-303.

Rozich, T. J. 1989. Evaluation of the Pere Marquette River Electrical Lamprey Barrier.
Michigan Department of Natural Resources Fisheries Division.

Sakai, K., M. Nomura, F. Takashima, and H. Oto. 1975. The Over-Ripening Phenomenon
of Rainbow Trout -- II. Changes in the Percentage of Eyed Eggs, Hatching Rate and
Incidence of Abnormal Alevins During the Process of Over-Ripening. Bulletin of the
Japanese Society of Scientific Fisheries, 41 pp 855-860.

Schadt, T. H., R. G. Metzgar, R. E. Carman, and J. H. Neuner. 1985. Background and
Assessment of a Berm/Fish Passageway Designed to Facilitate Upstream Migration
Past a Tailrace Area. In: Symposium on Small Hydropower and Fisheries, May 1-3,
1985-Aurora, Colorado. The American Fisheries Society. Bethesda, MD. 497 pages,
pp 409-415.

Seelye, J. G. 1989. Evaluation of the Ocqueoc River Electrical Weir for Blocking Sea
Lampreys. U.S. Fish and Wildlife Service, Hammond Bay Biological Station,
Millersburg, MI, 7 pp.

Taug, D. 1994. Personal communication between J. Downing, Stone & Webster, and D.
Taug, FERC-Portland Regional Office, June 16, 1994.

Vogel, D. A., K.R. Marine, and J.G., Smith. 1990, A Summary of Evaluations of Upstream
and Downstream Anadromous Salmonid Passage at Red Bluff Diversion Dam on the
Sacramento River, California, U.S.A. In: Proceedings of the International
Symposium on Fishways 1990 in Gifu, Japan.

Wagner, C. H. 1967. Fish barrier dams. Memo Dated August 23, 1987. Fish Facilities
Section, Columbia Fisheries Program Office, Bureau of Commercial Fisheries.

Weaver, C. 1963. Influence of Water Velocity Upon Orientation and Performance of Adult
Migrating Salmonids. U.S. Fish and Wildlife Service Fishery Bulletin, 63 pp 97-122.

Whelan, G. 1994. Michigan Department of Natural Resources. Personal communication
with J. Downing, Stone & Webster.

Page 52 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

TAILRACE BARRIER DESIGN: N/A

BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A

TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A

COMMENTS:

Although no fish barriers have been installed at Wilder and no fish have been reported to
be delayed or injured in the project’s tailrace or draft tubes, the unique design of the third

unit and its ability to provide attraction water to the fish ladder at all river flows may
alleviate any potential problems.

Page 70 Impacts of Hydroelectric Plant Tailraces on Fish Passage


WATER ELEVATION

WEIR PICKETS

—

FLOW

HINGED SUPPORT

BLADDER
~—

FIGURE 3-5
PNUEMAT ICALLY
OPERATED WEIR

TAILRACE BARRIER STUDY
SOURCE: MODIFIEO FROM MES 1993

Page 22

Impacts of Hydroelectric Plant Tailraces on Fish Passuge


Annotated Bibliography

EFFE IN PASSAGE:

At certain flow regimes (dependent on total river flow and discharge levels from the
powerhouse), powerhouse discharges during generation periods because of false attraction
of fish to the tailrace flow can inhibit upstream salmonid migration. There also is potential
for injury and mortality of fish that enter the powerhouse discharge canals and strike walls
or the turbine runners.

TAILRACE BARRIER DESIGN:

To reduce the false attraction of fish to the powerhouse discharge canals, a hydraulic
attraction to the project bypass was created by constructing a fish berm (lowhead dam) at
the upstream end of the powerhouse. The berm extends across most of the river
(perpendicular to the flow) from the bank opposite the powerhouse. A plume, with water
velocities approaching 7 fps (depending on discharge), is created from the constriction of
the river flow. The accelerated flows created by the berm make the main river channel
more distinguishable to upstream migrants as they approach the Jackson powerhouse during
periods of power generation. The installation of screens at the powerhouse also was
considered for preventing fish from entering the discharge canal. Although screens may
reduce any fish injury or mortality from canal wall and turbine contacts, they would not
alleviate the problems associated with false attraction.

BIOLOGICAL EFFECTS OF TAILRACE BARRIER:

At the time this paper was presented, a field evaluation of the fish berm had not been
completed. Based on the berm design, however, upstream migration delays and fish injury
and mortality from fish entering the discharge canals should be reduced. Tailrace associated
injury and mortality may be further reduced if screens are installed and the berm remains
in place. If the screens are installed and the berm is removed, migration delays most likely
would still occur and there may be injury and mortality from fish striking the screens in
attempts to enter the discharge canals.

TAILRACE BARRIER EFFECTS ON PROJECT OPERATION:

No lost generation should occur due to the fish berm because it is located on the main river
channel near the tailrace area of the powerhouse. There may be maintenance costs
associated with the berm, as well as with screens.

COMMENTS:

Based on its design, the fish berm installed at the Jackson Project should facilitate fish
migration past the project’s powerhouse during periods of generation. Without screens, fish
can still enter the powerhouse discharge canals, but would be less likely to do so because

Page 88 Impacts of Hydroelectric Plant Tailraces on Fish Passuge


survey were collated and summarized, and
Section 3 presents the results.

3.0 TECHNICAL SUMMARY

The literature search and survey
indicate that there is little pertinent
information on tailrace effects on fishery
resources. Most available data on
tailraces are related to fish passage
facilities. Further, there are few data on
effectiveness (in terms of numbers of
spawners or escapement) of tailrace
barriers at existing hydroelectric facilities.

The literature focuses most
commonly on Pacific salmonids. Most
survey responses were from projects with
anadromous salmonid runs. The following
discussion focuses on anadromous
salmonids with occasional reference to
other anadromous, catadromous, and
resident fish populations, as applicable.

3.1. Tailrace Effects on Injury,
Mortality, and Migration Delay

The development of hydroelectric
power has dammed many river systems
that formerly supported large runs of
migratory species. Impoundments
associated with hydroelectric development
change river hydraulics so that tailraces
are the only areas of flowing water that
mimic historic river hydraulics. Fish are
attracted to tailraces by a number of
hydraulically related factors.

When turbine discharges or
spillway flows contain water from natal
streams located upstream of a hydro
project, migratory species detect the scent
of their natal streams and often will be

falsely attracted from fish ladder flows.
Some turbine discharges or spillway flows
compete with fishway entrance flows or
mask the presence of natural stream
channels. The greater volume of water
and higher velocities associated with
turbine discharges and/or spillway flows
are key factors that falsely attract migrants
from the best route of upstream passage.

Typically, there is more than one
area of turbulent flow at a hydro site. As
noted in Section 1, spillways, trash sluices,
and entrances to fishways or bypasses may
create tailrace-like conditions. Depending
on the project size and layout of dam,
powerhouse, and appurtenant structures,
each of these areas may attract fish.

Water quality, particularly desirable
water temperatures, also may attract fish.
Habitat (e.g., for resting, holding, and
feeding) is an important criterion of
attraction, but habitat desirability depends
more on water velocity. The high volumes
of water and residual energy of tailrace
flows can provide attractive habitat to
some species. Areas of turbulence that
generally attract fish also can become
zones of exclusion if velocities in these
areas are excessive. Each project is
unique, however, and there is relatively
little documentation about the extent of
adverse effects at existing hydro sites.
Consequently, there may be other physical
characteristics beyond those noted in this
report that may be identified through
future research as important determinants
of tailrace attraction.

Attraction of migrants to tailraces
may result in injury, mortality, or a
substantial delay in migration and

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 3


Annotated Bibliography

Fleming, D. F., and J. B. Reynolds. 1991. Effects of spawning-run delay on spawning
migration of Arctic grayling. American Fisheries Society Symposium 10:299-305.

MIGRATION DELAY
ARCTIC GRAYLING

GAMETE MATURATION
HABITAT SELECTION

LOCATION OF STUDY:

Fish Creek, a tributary of the Jack River, Cantwell, Alaska.

E RISTICS: N/A
ICAL RISTICS: N/A
PROJECT EFFECTS ON UPSTREAM FISH PASSAGE: N/A

TAILRACE BARRIER DESIGN: N/A

ICAL F TAILRACE BARRIER: N/A
LRACE B. R EFFECTS ON P! E PERATION: N/A
COMMENTS:

This study examined the effects of delaying the spawning migration of Arctic grayling by
collecting fish at a weir and holding them for 3, 6, or 12 days before tagging and releasing
them. Tagged fish were recaptured at upstream traps and assessed for gamete maturation.
Based on the data from recaptured fish, migration rates and gamete maturation were
determined for each delay period. Of the fish initially captured, most males and about half
of the females were classified as ripe (ready to spawn). During the holding periods more
than half the females advanced in maturation level and the proportion of ripe males did not
change considerably. From these observations, it was concluded that migration timing is
more important for female spawners than for males.

The response of fish to delays was exhibited in subsequent migration rates and appeared
more closely related to maturation status at time of release than to length of delay.
Migration rate of females increased with the level of maturation regardless of the number

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 71


Annotated Bibliography

National Marine Fisheries Service. 1993. Environmental & Technical Services Division,
Portland, OR. Delay and injury associated with hydroelectric project powerhouses, draft
position paper.

WORD.
MIGRATION DELAY

INJURY AND MORTALITY
BARRIERS
OPERATION MODIFICATIONS

LOCATION OF STUDY: N/A

PROJECT CHARACTERISTICS: N/A

BIOLOGICAL CHARACTERISTICS: N/A

PROJECT EFFECTS ON UPSTREAM FISH PASSAGE: N/A
TAILRACE BARRIER DESIGN:

The paper examined several exclusion methods developed to prevent adult upstream
migrants from entering tailrace areas at hydroelectric projects. For each exclusion method,
the discussion included the general purpose of the method (i.e., to block or guide fish), a
basic structural description of physical barriers, and an explanation of how the method
functions to achieve the desired effect. Exclusion method descriptions also included site
applicability information and addressed barrier maintenance and operation issues. Exclusion
methods that were discussed included diffuser barriers, hydraulic barriers, electrical barriers,
operational changes, and modifications to stream channels. The following discussion
summarizes the information that was provided for each method.

Diffuser barriers are designed to minimize attraction of fish to tailrace areas by reducing
discharge water velocities. Diffuser barriers reduce water velocities by distributing flow over
a relatively large area. It was recommended that average diffuser velocities not exceed 1
fps. Absence of backwater effects was cited as an advantage to diffuser barriers. Several
types of diffuser barriers have been designed, including vertical (or inclined) and horizontal
barriers, and variable slope weirs. Vertical diffusers, which are the most common, consist
of a barrier rack with a maximum 1 inch clear spacing between bars. The bar racks are
inclined in the downstream direction and should create even flow distributions with an
average flow-through velocity of 1 fps. Horizontal diffusers are used to redirect the turbine
flow from its horizontal direction upward through a flat bar barrier. This creates an

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 77


CONTENTS

Page
EXECUTIVE SUMMARY ......... 0c cece eect eee eee eee e ene n eens v
1.0 INTRODUCTION .......... cece cee ene eee eee nenes 1
2.0 METHODS ....... 0. ccc ccc eee eee een e ene nee 1
3.0 TECHNICAL SUMMARY ........ cece cece eee eee e teen eeee 3
3.1 Tailrace Effects on Injury, Mortality, and Migration Delay ........ 3
3.1.1 Injury and Mortality ©... 06... ccc cece eee eee
3.1.2 Migration Delays ........... .
3.1.3 Summary of Tailrace Effects
3.2 Description of Tailrace Barriers, Modified Project Operation,
and Spill oo... cece cece eee een e een eeees
3.2.1 Tailrace Barriers
3.2.2 Modified Project Operation and Spill to Reduce
Tailrace Impacts 2... . 66. e cece eee eects 29
3.2.3 COStS oo. ccc cece cece eee een e een een eens 31
3.2.4 Summary .... 0. cece eee eee eee eens 32
4.0 DISCUSSION ... 0... 6c ccc eee enenee 33
4.1. Summary of Current and Potential Applications of Upstream
Fish Migration Protection Technologies
42 Additional Studies 2.0.0... cece eee eens
4.2.1 Biological Studies 0.1.0... ccc cece ee eee tenes
4.2.2 Hydraulic Studies ...... 6. 00sec eee eee eee teen eee
4.3 Guidelines for Evaluating Agency Requests for Tailrace Barriers .. 42
43.1 Need wo... c cece cece ect teeter eee teen teen eees 42
4.3.2 Feasibility 0... ccc eee eee eee eee 43
4.3.3 Effectiveness .. 0.0... ccc cece cece eee te tenes 44
4.3.4 Cost... ccc cece eee cnet eee ee eenee 45
5.0 CONCLUSIONS .... 0... eee e eee nee 45
6.0 LITERATURE CITED ........ 00. cece cece eee eens 48
APPENDIX ANNOTATED BIBLIOGRAPHY ......... 0.00 cece ee eeeenenee 54

Impacts of Hydroelectric Plant Tailraces on Fish Passa; Page vii
ge ge


Annotated Bibliography

International Pacific Salmon Fisheries Commission. 1976. Tailrace delay and loss of adult
sockeye salmon at the Seton Creek Hydroelectric Plant. Report No. 648. New Westminster,
B.C., Canada. 74 pages.

WORD:
FALSE ATTRACTION

SOCKEYE/PINK SALMON
MIGRATION DELAY

ATION OF DY:
Seton Creek hydroelectric project, the Fraser River, Lillooet, British Columbia, Canada.
PROJE HARA RISTICS:

The Seton Creek project is composed of a concrete diversion dam on Seton Creek, a 12,500
foot power canal, and a powerhouse that is located on the Fraser River 4,000 feet
downstream from its junction with Seton Creek.

BI ICAL CHARA RISTICS:

Adult sockeye migrate upstream each year to spawning grounds located above the Seton
diversion dam. Two distinct sockeye populations migrate biannually into Seton Creek; once
in the summer, and again in the fall. The majority of pink salmon spawn in river reaches
below the diversion dam, less than 10 percent spawn above the diversion dam.

PROJECT EFFECTS ON UPSTREAM FISH PASSAGE:

This study concluded that salmon populations were being depleted due to migration delay,
injury, and mortality associated with the project’s tailrace. Injuries resulted from turbines,
draft tube entry, and attraction to leakage flows through the wicket gates, which fish follow
into the turbines. During periods of large discharge flows, sockeye are prevented from
reaching the turbines, eliminating the possibility of turbine runner contact.

TAILRACE BARRIER DESIGN:

Although no physical tailrace barrier was installed at this site, several methods were assessed
to reduce fish injury and mortality in the tailrace. Plant shut-downs were implemented to
reduce false attraction; however, leakage into the tailrace through the plant wicket gates
continued to attract some sockeye. An increased discharge of 1,000 cfs through the spillway
was evaluated as a means to reduce sockeye injury, mortality, and migration delay in the

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 75


Annotated Bibliography

TAILRACE BARRIER DESIGN:

Grates were installed at the powerhouse discharges in response to the reported losses of
adult upstream migrants at the Winchester Project. The grates were set flush with the draft
tube exit and had 1-inch bar spacing. The grates were installed in pairs at each turbine
outfall to allow cleaning during power generation.

I E F TAILRACE TER:

Because the draft tube grates were installed based on the findings of this study, no biological
evaluation had been conducted; however, monitoring was proposed to determine the
effectiveness of the grates. Although injury to downstream migrants was identified from
effects of the upstream bypass facility, the report did not identify impacts on downstream
migrants from impingement on the tailrace grates.

T. JER EFFE! IN PROJE PERATION:

Because the grates were installed at the draft tube opening, it is possible that they could
influence power generation. There also would be general maintenance and operational
costs.

COMMENTS:

This study was conducted during the first year of operation of the Winchester Project, and
initially, injury and mortality were not a concern. However, cursory surveys were conducted
to monitor the effect of the project on upstream fish migrations. Presence of dead adults
downstream of the project prompted more detailed surveys and assessment of the project’s
impact on upstream migrants. Relative flow volume appeared to be a major factor in
determining the migration path of adult salmonids as they approached the project. At
higher flow levels more fish were attracted to the tailrace than to the spillway because a
greater proportion of the total flow passed through the powerhouse than did at lower flow
levels. During underwater surveys fish were observed entering the draft tubes while the
plant was generating. Based on observations of mortality, injury, and fish movements in the
tailrace, the study concluded that tailrace and discharge areas caused loss of 1.7 percent and
0.2 percent of the returning Chinook and Steelhead at Winchester Dam. Although it was
not discussed, migration delays also may have occurred at the Winchester Project because
fish were attracted to the draft tubes at higher flow levels.

U.S. GOVERNMENT PRINTING OFFICE: 1995-395-906-30717

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 101


Annotated Bibliography

Sakai, K., M. Nomura, F, Takashima, and H. Oto. 1975. The over-ripening phenomenon
of rainbow trout -- II. Changes in the percentage of eyed eggs, hatching rate and
incidence of abnormal alevins during the process of over-ripening. Bulletin of the Japanese
Society of Scientific Fisheries 41:885-860.

RAINBOW TROUT

GAMETE MATURATION
MIGRATION DELAY

LOCATION OF STUDY: N/A

PROJECT CHARACTERISTICS: N/A

BIOLOGICAL CHARACTERISTICS: N/A

PROJECT EFFECTS ON UPSTREAM FISH PASSAGE: N/A
TAILRACE BARRIER DESIGN: N/A

BI ICAL EFF! IER: N/A
TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A
COMMENTS:

This study examined the viability of over-ripened ova of female rainbow trout. Eggs were
stripped at 5-day intervals beginning immediately after ovulation and then artificially
fertilized. Percent eyed, hatching rate, and alevin deformity rate were recorded for each egg
group. The percentage of eggs eyed and the hatching rate exceeded 70 percent for eggs that
were stripped within 10 days of ovulation. These values decreased to 0 percent for eggs
stripped 1 month after ovulation. The percentage of deformed alevins increased with the
time of stripping. The results of this study have significant implications for spawning
migration delays experienced by salmonids. If upstream-migrating females have ovulated,
migration delays could result in decreased egg viability and hatching rates and increased
rates of alevin deformity. Consequently, considerable recruitment losses could be
experienced for the affected population.

Page 86 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

Barry, T., and B. Kynard. 1986. Attraction of adult American shad to fish lifts at Holyoke
Dam, Connecticut River. North American Journal of Fisheries Management 6:233-241.

ORDS

UPSTREAM FISH PASSAGE

FISH LIFT
AMERICAN SHAD
ATTRACTION WATER

ATION DY:

Hadley Falls Hydroelectric Project, Connecticut River, Holyoke, Massachusetts

PROJECT CHARACTERISTICS:

The Hadley Falls Project comprises the Holyoke dam, a powerhouse, and a power canal
system which provides water used by local industry for generation purposes. At the time of
this study, the Hadley Falls powerhouse had one generating unit (a second unit has since
been installed) with an additional unit located in the canal system. Fish passage is provided
by two fish lifts, and both are attached to the powerhouse. One fish lift collects upstream
migrants from the powerhouse tailrace and the other collects fish that move up the spillway.
The entrance to the tailrace lift collection area is located next to the powerhouse discharge
exits.

BIOLOGICAL CHARACTERISTICS:

Four species of anadromous fish that return to the Connecticut River to spawn are lifted
at the Hadley Falls Project each spring. These species include blueback herring, American
shad, sea lamprey, and Atlantic salmon. There also are Striped bass juveniles and shortnose
sturgeon at the Hadley Falls Project during the spring, but they are not currently lifted
upstream past the counting station to spawn. Atlantic salmon populations are being restored
to the Connecticut River, and the number of returning adults is still at low levels.
Generally, several hundred thousand blueback herring and American shad are lifted each
spring at the Hadley Falls Project.

PRO, FFE IN_UP! AM FISH PASSAGE:

The Holyoke dam is an impediment to upstream migrants. The operation of the two fish
lifts alleviates this problem and allows fish to reach historic spawning grounds upstream of
the project. The purpose of this study was to determine if there were problems with
American shad locating the entrance to the tailrace lift collection area.

Page 54 Impacts of Hydroelectric Plant Tailraces on Fish Passage


EPRI. 1992. Evaluation of Storage Lights for Fish Diversion at the York Haven
Hydroelectric Project. Electric Power Research Institute. Research Project 2694-01
Report Number TR-101703.

EPRI. 1993. Research Update on Fish Protection Technologies for Water Intakes. Electric
Power Research Institute. Project No. 2694-1. Palo Alto, CA.

Fedorenko, A. Y. 1989a. Information Related to Adult Injuries at the Puntledge Power
Plant Tailrace and any measures considered to ameliorate Damages. Draft Report
to Canada Department of Fisheries and Oceans, Vancouver, B.C.

Fleming, D. F., and J. G. Reynolds. 1991. Effects of Spawning-Run Delay on Spawning
Migration of Arctic Grayling. American Fisheries Society Symposium, 10 pp 299-305.

Fretwell, M. R. 1989. Homing Behavior of Adult Sockeye Salmon in Response to a
Hydroelectric Diversion of Homestream Waters. International Pacific Salmon
Fisheries Commission Bulletin XXV. Vancouver, B.C. 38 pp.

Hayes, F.R. 1953. Artificial Freshets and Other Factors Controlling the Ascent and
Populations of Atlantic Salmon in the La Have River, Nova Scotia. Fisheries
Research Board of Canada, Bulletin Number 99, 47 pp.

Haynes, J. M., and R. H. Gray. 1980. Influence of Little Goose Dam on Upstream
Movements of Adult Chinook Salmon, Oncorhynchus tshawytscha. U.S. National
Marine Fisheries Service Fishery Bulletin 78, No. 1, pp 185-190.

Heard, W. R. 1991. Life History of the Pink Salmon. In: Pacific Salmon Life Histories.
Edited by C. Groot and L. Margolis. University of British Columbia Press.
Nanaimo, 564 pp.

Hildebrand, S. G., Bell, M. C., E. P. Richey, J. J. Anderson, and Z. E. Parkhurst. 1980.
Analysis of Environmental Issues Related to Small Scale Hydroelectric Development
- Part II: Design Considerations for Passing Fish Upstream Around Dams
(Publication No. 1567). ORNL/TM-7396. Prepared for Assistant Secretary for
Resource Applications, U.S. Department of Energy by Oak Ridge National
Laboratory, Environmental Sciences Division, 78 pp.

Hilgert, P. J., W. K. Herschberger, and D, V. Smith. 1992. Evaluation of a Graduated
Electric Field as a Fish Exclusion Device - Final Report. Prepared for Puget Sound
Power and Light Company, Bellevue, WA, Prepared by Beak Consultants, Inc.,
Kirkland, WA, 29 pp.

Page 50 Impacts of Hydroelectric Plant Tailraces on Fish Passage


length of time between ovulation and
fertilization (Sakai et al. 1975).

Fish may spawn in suboptimal
habitats if they cannot reach preferred
spawning areas because of migration
delay. Adult salmonids at the Red Bluff
Diversion Dam on the Sacramento River
in California experienced migration delays
that caused fish to spawn below the dam
where summer water temperatures were
too warm for egg survival (Vogel et al.
1990; Brown 1991). Delay also may
prevent some fish from spawning even if
they reach preferred spawning areas,
because inappropriate environmental cues
are present (Hoar 1953) (e.g., low water
temperatures inhibit ovulation in some
salmonid species) (Goryczko 1972 [cited in
Bye 1984]). Species that spawn shortly
after reaching spawning areas (e.g., most
Pacific salmon and clupeids) may be more
affected by delays than species that may
not spawn for months after entering their
natal river basin (e.g., Atlantic salmon,
summer-run steelhead, spring chinook).
However, inability of individuals of the
latter group to reach suitable holding
areas before spawning may cause
prespawning mortality that would not
otherwise occur.

Resident species delayed during
annual migrations also may spawn in
suboptimal habitats and suffer lower egg-
hatching rates and larval survival. A study
on the effect of spawning-run delays on
Arctic grayling determined that delays
caused fish to stop migrating before
reaching their upstream goals (Fleming
and Reynolds 1991). Migration rate was
positively correlated to maturation level,
and more mature females did not travel as

far upstream as less mature females.
Delays of 3 days were critical for females
near the end of their spawning run. Study
results indicate that delayed graylings may
spawn in unsuitable habitats because they
cannot reach upstream spawning areas due
to biological (e.g., level of maturation) and
physical (e.g. water temperature)
constraints.

Delays also may kill migrants
before spawning if energy reserves, which
are used to reach breeding areas and for
spawning, are completely depleted. This
is especially true for migratory species that
do not feed during migration. Energy
depletion may be exacerbated by
increased stress levels caused by migration
blockages. Energy stores can be
significantly reduced at a powerhouse or
spillway if fish continually make attempts
to ascend turbine discharge or spillway
flows. Pre-spawning death from excessive
delays has been cited at several projects
on the Columbia River and in other river
basins throughout North America
(Burgner 1991; Heard 1991).

Effects of migration delays on
spawning success are difficult to
extrapolate to the recruitment of young to
the spawning stock of a population.
Depending on the species, recruitment
depends on the number of spawners,
environmental factors that influence
survival, or a combination of number of
spawners and environmental factors.
Environmental factors may influence
recruitment when resources (preferred
habitats and food) are limited and fish
densities are high. If recruitment is
directly related to the number of
spawners, fewer spawners will result in

Page 12

Impacts of Hydroelectric Plant Tailraces on Fish Passage


For example, small populations of sauger,
sturgeon, or other species may be present
or conjectured to be _ present.
Radiotelemetry may be a useful technique
to document this issue. Small populations
may not be important unless the species is
threatened or endangered, and
documenting the presence of rare species
is often difficult. Agencies often dictate
that all sampling must be nondestructive.
However, presence of a rare migratory
species sometimes can be confirmed by
trapping, electrofishing, or netting
preferred habitats in the tailwaters at the
appropriate season.

The second biological issue is
whether or not fish can enter draft tubes
during generation, thereby exposing
themselves to risk of injury or death. One
way to identify a species’ capability to
enter the draft tubes is through release
and monitoring of radiotagged fish in the
tailrace. If actively migrating fish are
radiotagged and released into the
tailwaters, movement into the draft tube
may be identified by well-positioned
receiver antennas.

Discharge hydraulics also can be
studied. There is abundant literature on
fish swimming capabilities, but little on
draft tube hydraulic conditions. As a first
measure of draft tube tailrace water
velocities, the open area of the draft tube
can be divided by unit flow to yield
average exit velocities; additional sampling
usually is required. Tailrace flow
distributions are often skewed because the
water rotates during passage through the
generating unit. Average velocity
estimates, therefore, may not accurately
represent the velocities migrating fish

would swim against in the tailrace. A
velocity profile of the tailrace discharge
can be collected with a flowmeter
mounted on a downrigger or from a
mounting rack positioned in draft tube
dewatering slots (if available).

The third biological issue to study
is whether or not migratory species that
are capable of entry into the draft tubes
are uninjured, or are injured in numbers
that are a threat to population levels. The
simplest way to document injury is to
search the river banks and tailwater areas
during migration. Dead and injured fish
showing injury consistent with turbine
blade strikes and abrasion from concrete
can be assumed to be injured by the
project. Injury may be difficult to
document, however, because some dead or
injured species may settle to the river
bottom or be consumed by predators.

To demonstrate population effects,
impacts must be assessed. Data on
population size, age structure,
reproductive capacity, numbers of fish
killed or injured, and possibly
compensatory survival are required.
Population modeling also may be
necessary. Available data may limit the
effectiveness of the modeling especially if
modeling of multiple species is
undertaken.

A tagging study can provide
valuable information on tailrace hydraulics
and fishway entrance conditions. These
biological studies should be done under a
variety of operating conditions to identify
conditions that may cause delay and
injury. These studies can identify how fish
respond behaviorally to modified project

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 41


43.4 Cost

Cost of mitigation devices is always
an important consideration in balancing
feasibility with effectiveness. There is
limited transferable experience with cost
of tailrace barrier installation.

To determine costs for tailrace
barriers, design data that is more detailed
than that available at a conceptual level
must be developed. Because there is little
information on costs of tailrace barriers
and site-specific conditions can be highly
variable, capital costs will probably be
identified from quantities of materials,
Backfitted tailrace barriers are more costly
than those installed with new project
construction.

Operational costs should include
effects of the tailrace barrier on power
generation and maintenance.
Maintenance may be a considerable factor
if a device requires on-site maintenance
personnel throughout the migration
season, especially if the project typically
operates in an unmanned mode.

5.0 CONCLUSIONS

Available literature was reviewed
and a survey of sites with installed or
proposed tailrace barriers was conducted.
Data were collected and the following
conclusions were made:

Population Effects

. No studies were identified
on the specific effects of
tailrace delays on migratory
fish populations.

Migration delays can limit
the upstream extent of
migration.

awning Su Eff

Delays of as little as 3 days
may have critical effects on
the spawning success of a
species,

Delays may cause upstream
migrants to spawn in
suboptimal habitat or not
spawn at all.

Delays can cause mortality
to migrating fish by
reducing energy reserves.

Causes of Injury

Swimming speed of target
species influences their
ability to enter dangerous
areas of the tailrace.

Turbine elevation, velocity
conditions, and turbine type
influence the susceptibility
of fish to injury in the
tailrace.

Fish are injured in tailrace
areas from contact with the
turbine runners, abrasion on
the walls of the tailrace
structure, or from non-
contact water-quality related
impacts.

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 45


Annotated Bibliography

less (p<0.05S) than delays observed at other Columbia and Snake River dams. (Note:
Brown, 1994 says more recent studies show average delays are approximately 20-30 hours.)
Several factors were identified that may have been contributing to the observed migration
delays at Little Goose, including dam spill, turbine discharge, and trapping operations.
Dropbacks and milling were common in the spill area and turbine operation reduced salmon
passage through the fish ladder (i.e., false attraction). Multi-dam passage delays were cited
as a possible factor in declines of fall-run chinook salmon because the delays may reduce
spawning success.

Page 74 Impacts of Hydroelectric Plant Tailraces on Fish Passage


mortality at the tailrace barrier and in the
Puntledge bypass when flows were high
(Department of Fisheries, Canada 1962;
Marshall 1973). This barrier was deemed
unsatisfactory, and design improvements
were recommended in 1988.

Contact-type injury or mortality
associated with powerhouse structures has
been identified at a number of other sites
where there are migratory salmonids. The
discharge from the powerhouse at the
Seton Hydroelectric Project on the Fraser
River attracts migrants that enter the draft
tube and are injured or killed (IPSFC
1976; Bengeyfield 1982). During high
discharge flows at Seton (e.g., full load
operation), fish are not able to ascend the
full length of the draft tubes because of
excessive velocities (greater than 20 fps
immediately downstream of the turbine
runners). However, at lower flows and
during start-up following shut-down
periods, fish are able to enter and travel
upstream into the draft tubes.

Tailrace-related injuries sustained
by adult chinook salmon and steelhead
trout were reported at the Winchester
Hydroelectric Project on the North
Umpqua River, Oregon (Williams 1985).
Turbine load and subsequent water flow
rates induced migrants to enter the
powerhouse draft tubes and contact
turbine runners. Project flow distributions
determined the passage route of migrants;
when spillway flows were a greater
proportion of the total flow, migrants
typically bypassed the project’s tailrace.
The turbines at Winchester were often
operated at lower generation levels to
reduce downstream migrant mortality.
The lower generation levels, however,

resulted in lower discharge velocities and
made it easier for migrants to ascend the
draft tubes and contact the runners.

Injuries sustained in tailrace areas
also can lead to latent mortality.
Abrasions and lacerations that leave fish
vulnerable to secondary disease such as
fungus growth, when combined with other
stresses, are possible sources of mortality.

Tailrace-related injury and
mortality also have been reported for
migratory freshwater fish species. At the
Peshtigo Hydroelectric Project on the
Peshtigo River in Wisconsin, mortality of
lake sturgeon and adult salmonids was
attributed to fish entering draft tubes and
striking turbine runners (Krueger 1989).
Specifically, the runners for one of the
plant’s two turbines are located at the
normal tailwater elevation (the runner for
the other turbine is about 3.5 feet above
this elevation). Dead fish that were
recovered immediately downstream of the
project on several occasions exhibited
injuries and marks indicating contact with
mechanical structures. Plant operations
were modified (the suspect unit was
operated continuously) to try to prevent
fish from entering the draft tube; however,
injury and mortality persisted. A bar rack
was then designed and installed at the
draft tube exits to exclude entry of larger
fish.

Another injury type associated with
tailraces is fish stranding. Fish can
become attracted to a tailrace by the
hydraulics, water temperature, natal scent,
or other features. When flows subside or
cease, fish may become stranded in pools

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 7


Burgner, R. L. 1991. Life History of Sockeye Salmon. In: Pacific Salmon Life Histories.
Edited by C. Groot and L. Margolis. University of British Columbia Press.
Nanaimo, 564 pp.

Bye, V. J. 1984. The role of environmental factors in the timing of reproductive cycles.
In: B. W. Potts and R. J. Wotton (eds.), Fish reproduction: strategies and tactics.
Academic Press, Harcourt Brace Jovanovich, Publishers, London.

Clay, C. H. 1961. Design of Fishways and Other Fish Facilities. Department of Fisheries
of Canada, Queen’s Printer, Ottawa. 301 pages.

Clay, C. H. 1991. Upstream Atlantic Salmon (Salmo salar) Passage. In: Proceedings of
the Workshop on Fish Passage at Hydroelectric Developments, March 26-28, 1991,
St. Johns, Newfoundland. Canadian Technical Report of Fisheries and Aquatic
Sciences No. 1905.

Department of Fisheries, Canada. 1958. The Fisheries Problems Associated with the Power
Development of the Puntledge River, Vancouver Island, B.C. 40 pp and 9
Appendices.

Department of Fisheries, Canada. 1962. Brief Outlining the Need for Fish Protective
Facilities at the Puntledge River Hydroelectric Development. Presented to Dr. H.F.
Angus, Commissioner Puntledge River Inquiry, Vancouver, B.C.

de Vlaming, V. L. 1972. Environmental control of teleost reproductive cycles: a brief
review. Journal of Fish Biology, 4 pp 131-140.

Doret, S.C. 1987. A Fishway that Generates Power. Hydro Review, October, pp 22-25.

Dunning, D. J., Q. E. Ross, P. Geoghegan, J. J. Reichle, J. K. Menezes, and J. K. Watson.
1992. Alewives Avoid High-Frequency Sound. North American Journal of Fisheries
Management. Vol. 12, No. 3, pp 407-416.

Ebel, W. J. 1969. Supersaturation of Nitrogen in the Columbia River and Its Effects on
Salmon and Steelhead Trout. U.S. Fish and Wildlife Service Fishery Bulletin, 68
pp 1-11.

EPRI. 1986. Assessment of Downstream Migrant Fish Protection Technologies for
Hydroelectric Application. Electric Power Research Institute Report No. EPRI AP-
4711. Palo Alto, CA.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 49


(this page intentionally left blank)



Annotated Bibliography

dam first with decreasing flow from the center of the spillway to the fishway. Obviously, at
dams that do not have spill gates, controlling the flow in this manner would not be possible.
Fishway attraction problems are not always related to spill; proper entrance configurations
and water volume and velocity ultimately determine the ability of a fish ladder to pass fish.
The location of an entrance for fishways adjacent to a powerhouse also is extremely
important. It was stated that the farther downstream an entrance is from the powerhouse,
the more difficult it will be for fish to find. Entrances that are located too far downstream
from a powerhouse could lead to false attraction of upstream migrants to turbine discharge.
Large powerhouses with many units may have fishway attraction problems because fish can
be attracted to the middle of a powerhouse. This situation often can be alleviated by
constructing a flume along the length of the powerhouse that has multiple entrances and
leads to a fishway.

Several types of barrier dams are discussed as means to alleviate false attraction of fish to
spillways and tailraces and to guide fish towards fishway entrances. The author provides
descriptions and examples of buttress-type dam, a hydraulic barrier, and a concrete addition
to a rock outcrop. Important design characteristics for all three of these barriers included
that the hydraulic head should be equivalent to 10 feet and that fish did not sustain injuries
as a result of jumping at the barriers. By design, the buttress-type barrier has a channel
underneath the crest that fish either swim or fall into. The channel can have directional
flow that leads fish to a fishway entrance. The hydraulic barrier is a concrete structure that
produces high velocities and turbulence in the hydraulic jump that are sufficient to prevent
fish from passing upstream. This barrier type can be angled towards a fishway to guide
upstream migrants to the entrance. The last barrier that was described was a concrete
addition to an natural rock outcrop downstream of the spillway. A minimum of 10 feet of
head was achieved preventing fish from reaching the spillway.

This book is an excellent general reference for reviewing upstream fish passage concepts.
The discussions are not filled with technical jargon and detailed figures make each concept
easy to understand.

Page 66 Impacts of Hydroelectric Plant Tailraces on Fish Passage


WEIR PICKETS

WATER ELEVATION

FLOW

HINGED SUPPORT

__HrpRAUL 1 CYLINDER
<n
SS ae

FIGURE 3-4

HYDRAUL I CALLY
OPERATED WEIR

TAILRACE BARRIER STUDY
‘SOURCE: MODIFIED FRCM WWFS 1999

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 21


Annotated Bibliography

Clay, C.H. 1991. Upstream Atlantic salmon (Salmo salar) passage. In: Proceedings of
the Workshop on Fish Passage at Hydroelectric Developments, March 26-28, 1991, St.
Johns, Newfoundland. Canadian Technical Report of Fisheries and Aquatic Sciences No.
1905.

aes

2 Se
KEYWORDS
ATLANTIC SALMON

FISHWAY ENTRANCES
FALSE ATTRACTION

LOCATION OF STUDY: N/A
PROJECT CHARACTERISTICS: N/A
BIOLOGICAL CHARACTERISTICS: N/A
PR H_ PASSAGE: N/A
TAILRACE BARRIER DESIGN: N/A

EFFE! F_ TAILRACE BARRIER: N/A
TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A
COMMENTS:
In a general discussion of upstream Atlantic salmon passage, the author briefly discusses
fishway entrance positions and possible techniques for improving a fish’s ability to locate an
entrance. It was concluded that fishway entrances should be placed at the furthest point
upstream to which fish can swim before being impeded by obstacles (e.g., a dam or natural
falls). Also, increased attraction flows or tailrace barriers (barred screens, barrier dams,

electrical fields) were cited as ways to improve upstream fish passage where fishway
attraction flows compete with tailrace discharges.

Page 64 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

COMMENTS:

The purpose of this study was to determine if upstream migrants were being injured or
killed in the draft tubes of Plant 2 of the Snoqualmie Falls Project. Shoreline, underwater,
and angler surveys were used to assess the presence of dead or injured adult salmonids in
the area downstream of Plant 2. Surveys were conducted from August 1991 through
February 1993. Survey data indicated that upstream migrants were not being injured or
killed in the Plant 2 draft tubes. Because fish could not ascend the draft tubes when the
station was operating at full load, any potential injury and mortality probably would occur
during low generation periods (e.g., start up and power down or low flow conditions). To
evaluate the potential for fish to enter the draft tubes during these times, underwater
surveys also were scheduled during worst case generation scenarios. However, after two
surveys with no observations of live or dead fish, this portion of the study was canceled.
Based on the evidence presented in this report, it is likely that there is not considerable
potential for upstream migrants to be injured or killed in the Plant 2 draft tubes at the
Snoqualmie Falls Project. Additional survey data from worst case scenarios when fish are
also known to be in the tailrace area would be useful to either support this conclusion or
to warrant the use of a tailrace barrier.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 57


Migration can be delayed at any
hydroelectric project when migrants are
falsely attracted to areas other than
natural stream channels or fishway
entrances. False attraction usually occurs
at projects with considerable mainstem
bypass reaches. Long bypasses with
relatively low flow releases may not
contain enough natal scent to attract fish
from tailrace flows especially if the bypass
teach contains inflow from other stream
channels or tributaries. Migrants typically
are attracted away from the main river
channel and into a tailrace by the
discharge from the powerhouse. False
attraction also can occur in the vicinity of
powerhouse and spillways if turbine
discharge and spill produce hydraulic
conditions that mask fishway attraction
water.

Level of impact depends on fish
species. Resident fish populations may
not be affected by delays if spawning takes
place over several months. Some resident
fish species may have shorter spawning
seasons, however, that depend on distinct
environmental conditions (e.g., sturgeon).

Migratory fish may be most
affected by migration delays because they
travel long distances to reach spawning
areas and typically spawn during distinct
time periods. Lengthy delays may deplete
energy reserves and lead to spawning
failure.

For migratory fish populations, the
loss of adult spawners due to delay, injury,
or mortality may result in lower spawning
success or recruitment. This is especially
true if spawning populations are low. For
catadromous species, there may be some

injury and mortality of upstream migrating
juveniles. Migration delays, however, do
not have the same effects on catadromous
juvenile upstream migrants; there may,
however, be some effect on survival,
growth, and maturation. It is important to
identify sources of injury, mortality, and
delay and to implement the appropriate
protective measures to ensure effective
passage of all age classes and species of
migratory fish.

Many false attraction problems can
be eliminated or reduced by improving
fishway entrance location and hydraulics,
or by modifying powerhouse operations or
spillway flow amount and distributions, as
discussed in the following section.

3.2. Description of Tailrace Barriers,
Modified Project Operation, and
Spill

Physical structures, behavioral
barriers, and modifications in project
operation and spill may alleviate
powerhouse-associated injury and
mortality or reduce migration delays.
Tailrace barriers are used specifically to
avoid injury to upstream migrants
especially where the project is upstream of
the terminus of fish migration. Effective
physical and behavioral barriers can limit
draft tube-related damage but may not
reduce migration delays unless specifically
designed to do so. Likewise, modified
project operation and spill regimes can
alleviate migration delays but cannot
eliminate injury and mortality at a
powerhouse. At sites where there are
injury and mortality and migration delays,
physical structures that guide fish to

Page 14

Impacts of Hydroelectric Plant Tailraces on Fish Passage


fishway attraction flows may not affect
generation capability, whereas an increase
in spill levels would decrease generation
potential.

For new hydroelectric
developments or retrofits to existing
projects, powerhouses and fishways can be
designed to minimize modified operation
and spill. At the Wilder Hydroelectric
Project on the Connecticut River in
Vermont, for example, a small hydro
turbine was added to the existing
powerhouse specifically to supply
attraction water to a fishway collection
area (Doret 1987). The new unit also
passes minimum required flows when the
larger units are not operating. This
innovative approach increases the
efficiency of the plant even when the
fishway is operating. The technique is
also in use at the Dalles North Shore
fishway and is planned for installation at
the McNary Dam.

Innovative solutions to upstream
migration problems can be implemented
but they depend on the site of the new
installation or retrofit. Innovative designs
always should be considered especially if
construction costs would not be
considerably greater than the cost of
alternative scenarios (e.g., lost generation
revenues because of modified powerhouse
operation or spill). Innovative solutions
are appropriate, however, only to the
extent that there is compelling evidence
that they work.

3.2.3 Costs

Depending on the selected barrier,
costs are incurred for installation,

operation, maintenance, and impacts on
power generation. Costs are highly
dependent on site characteristics, and
literature sources do not provide
meaningful values for the barriers
discussed. However, cost of each barrier
type and factors that contribute to overall
expense can be compared among barriers.
Factors influencing installation,
maintenance, and operation costs of
tailrace barriers include dimensions,
materials, and location. Power generation
impacts would depend on barrier type and
location.

Screens are the most expensive type
of barrier to install and maintain because
of cleaning requirements. At sites with
heavy debris loads, screens may require a
special cleaning device (e.g. a rake
system) or removal for cleaning. Tailrace
screen cleaning is often unnecessary if
debris is removed at the project intake.
Barrier dams generally have lower
installation and maintenance costs than
screens, but greater impacts on power
generation depending on proximity to the
powerhouse. Of the three barrier types,
behavioral barriers should be the least
costly to install and maintain and should
have the least impact on power
generation. Operating costs for behavioral
barriers, unless they are automated,
however, may be greater than for other
barrier types. Also, behavioral barriers
generally are less reliable than physical
barriers at blocking upstream fish
movement.

Backfitting tailrace barriers to
existing projects is more costly than
designing barriers into a new project.
Backfitted construction of this type in the

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 31


Hoar, W. S. 1953. Control and timing of fish migration. Biological Review 28:437-452.

International Pacific Salmon Fisheries Commission. 1976. Tailrace Delay and Loss ‘Of
Adult Sockeye Salmon at Seton Creek Hydroelectric Plant. Report No. 648. New
Westminster, B.C., Canada. 74 pages.

Klinect, D. A., P. H. Loeffelman, J. H. Van Hassel. 1992. A New Signal Development
Process and Sound System for Diverting Fish From Water Intakes. Proceedings of
the American Power Conference 1992, pp 427-432.

Krueger, R. A. 1989. Letter Dated August 3, 1989 from R. A. Krueger at Wisconsin Public
Service Corporation to N. Kutchery at Wisconsin DNR, 3 pp.

Loeffelman, P. H., D. A., Klinect, and J. H. Van Hassel. 1991. Fish Protection at Water
Intakes Using a New Signal Development Process and Sound System. Proceedings
of Water Power 1991, pp 355-365.

MacDonald, J. R., and R. A. Hyatt. 1973. Supersaturation of Nitrogen in Water During
Passage Through Hydroelectric Turbines at Mactaquac Dam. Journal of the
Fisheries Research Board of Canada, 30 pp 1392-1394.

Marshall, D. E. 1973. Progress Report on the Puntledge River Program, 1971 and 1972.
Tech. Rep. 1973-8. Department of the Environment Fisheries and Marine Service,
Pacific Region.

National Marine Fisheries Service. 1993. Environmental & Technical Services Division.
Delay and Injury Associated With Hydroelectric Project Powerhouses, Draft Position
Paper.

Nemeth, R. S., and J. J. Anderson. 1992. Response of Juvenile Coho and Chinook Salmon
to Strobe and Mercury Vapor Lights. North American Journal of Fisheries
Management Vol. 12, pp 684-692.

PacifiCorp. 1993. Additional Information Requested for Application for New License for
Major Projects-Existing Dam. Prepared for PacifiCorp by Harza. Vol. V, Item 13,

17 pp.

RMC and Sonalysts. 1993. Draft: Effect of Esonification on Juvenile American Shad
Movement and Behavior at Vernon Hydroelectric Station, 1992. March 1993,
103 pp.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 51


smallest upstream migrating fish of a
target species from becoming wedged or
gilled or from passing through the barrier.
To reduce such problems, 1-inch clear bar
spacing has been recommended for
tailrace barrier screens (NMFS 1993).
Bates (1992) recommends sizing the
spacing narrow enough to prevent fish
from injuring their eyes as they attempt to
push their way through the clear spaces.
To minimize jumping-related injury, it has
been recommended that average water
velocities should not exceed 1 fps and
should be uniformly distributed across the
entire area of a barrier screen structure
(NMFS 1993). When water velocities are
not uniform, there may be high-velocity
zones that induce fish to jump at the
barrier.

An important consideration for
diffuser barrier design is provision for
downstream migrants. To prevent
downstream migrant impingement,
removal of the barrier during outmigration
may be necessary. Alternatively, a
downstream fish protection/guidance
device can be used to prevent downstream
migrants from following the flows into the
upstream side of the tailrace barrier.

Fish injury is less likely with
horizontal diffusers (Figure 3-1). Unlike
vertical or inclined barrier screens (Figure
3-2) that are set at or nearly perpendicular
to the flow (ie. upright position),
horizontal diffusers are set parallel to the
flow. This design directs turbine discharge
upward, creating an upwelling effect. The
hydraulic conditions created by horizontal
diffusers minimize potential for injury
because fish are less likely to jump at
upwelling flows.

Variable-slope barriers (or weirs)
are designed to adjust to varying flow
levels and allow most debris to pass over
the screen and continue downstream (see
Figures 3-3, 3-4, and 3-5). NMFS
describes three types of variable-slope
weirs (floating, hydraulic, and pneumatic)
for use as tailrace barriers at hydroelectric
projects (NMFS 1993). All three types are
inclined downstream at an angle that
depends on water level. Most debris
contacting these screens will push the
screen downwards as the debris is carried
downstream by the flow. Hydraulic and
pneumatic screens also may need to be
mechanically lowered to facilitate passage
of debris.

Site-specific debris loads will affect
the feasibility of vertical, inclined, or
horizontal screens. Vertical or inclined
screens designed for sites with heavy
debris loads or with unscreened water
diversions may need a cleaning system
(eg., a rake device). Because these
structures are completely submerged,
horizontal screens are not easily cleaned
and are best suited for sites with light
debris loads or screened intakes.

Barrier screen location may affect
power generation because, to some extent,
screens reduce operating head. Generally,
the closer the barrier is to the project
tailrace, the more it will impact
generation. The height and bar spacing of
a screen also can affect tailwater
elevations and subsequently reduce
generation capacity. Generally, reductions
in operating head from a diffuser barrier
would be less than those from a barrier
dam. Barrier screens and bar racks
designed with an approach velocity of

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 17


Annotated Bibliography

Rozich, T. J. 1989. Evaluation of the Pere Marquette River electrical lamprey barrier.
Fisheries Division, Michigan Department of Natural Resources.

SEA LAMPREY

STEELHEAD TROUT

LOCATION OF STUDY:

Pere Marquette River, Mason County, Michigan.

PROJECT CHARACTERISTICS: N/A

BIOLOGICAL CHARACTERISTICS:

Adult sea lamprey migrate upstream in the Pere Marquette River each spring to spawn.
Lampreys are parasites that feed on the blood of fish. It is believed that they have
contributed to observed declines in many Great Lakes salmonid populations. Adult
steelhead trout also spawn in the Pere Marquette River each spring.

PROJECT EFFECTS ON UPSTREAM FISH PASSAGE: N/A
TAILRACE BARRIER DESIGN:

The electrical barrier was oriented perpendicular to the flow and was supported by five
wooden platforms (20 ft by 20 ft). Twelve Smith-Root Model GFFB 1.4U pulsators
provided the pulsed energy. Seven 1-inch wide by 1-inch thick steel bands were used as
electrodes and were imbedded in and hung from the wooden platforms. The pulsators (6
on each side of the river) were connected to the steel bands. The river was narrowed at the
site of the barrier with plastic sheet piling and the bottom was raised with limestone rock
to create a minimum water velocity of 5 fps across the barrier. During the latter stages of
the study, the voltage gradient typically increased from about 0.5 V/cm at the downstream
end of the platforms to 1.2 V/cm in the middle, after which it decreased to about 0.3 V/cm
at the upstream end (voltage was measured between the bands). Voltage was slightly higher
near the river bottom than near the surface (stream depth over the wooden platforms
ranged from 2 to 5.5 feet).

Page 84 Impacts of Hydroelectric Plant Tailraces on Fish Passage


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Annotated Bibliography

I ICAL EFFECTS OF TAIL! BARRIER:

The intention of the tailrace barriers that were discussed is to reduce tailrace migration
delay and alleviate injuries and mortality caused by draft tubes and turbine contact.
Diffuser barriers minimize false attraction flows that lead to migration delay and also can
be used to guide fish to a bypass canal. Hydraulic and electrical barriers prevent fish from
entering draft tubes and also can reduce migration delay. Operational changes may alleviate
migration delays and injury and mortality associated with tailrace areas. If tailrace barriers
are installed and operated properly, there should not be any additional delay, injury, or
mortality associated with their use.

TAILRACE B. JER EFFE! IN PROJE PERATION:

Aside from installation costs and the loss of power associated with screens that require
maintenance, economic loss due to tailrace barriers is not expected. There would be
economic loss to the extent that screens reduce effective head for the project. Economic
losses can also be expected from implementing operational changes that may reduce the
flow passing through the turbines resulting in lost power production or a complete plant shut
down.

COMMENTS:

This document was a working paper prepared by the National Marine Fisheries Service.
The paper provided information on different barrier types designed to prevent adult fish
from entering draft tubes and turbines. Fish injury, mortality, and spawning migration delays
are concerns at many hydroelectric sites and technology, and measures that can be applied
for reducing these problems were discussed. The paper discussed the effectiveness of
several barrier types and recommended why and when fish barriers or exclusion methods
should be implemented at powerhouse wasteways, tailraces, and tunnel outfalls. Discussions
of each barrier type included site-specific requirements for application and assessed the
effectiveness of a barrier for reducing negative impacts of upstream migrants from
hydroelectric project.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 79


Annotated Bibliography

Beak Consultants Incorporated. 1993. A study to determine the influence of the
Snoqualmie Falls Project on the injury and mortality of adult salmonids. Prepared for
Puget Sound Power & Light Company, Bellevue, WA.

WORDS

| PACIFIC SALMON
INJURY AND

ATION OF DY:

Snoqualmie Falls Hydroelectric Project, Snoqualmie River, Washington.

PROJECT CHARACTERISTICS:

The Snoqualmie Falls Project is composed of two generating stations, Plants 1 and 2.
Plant 1 is located at the base of Snoqualmie Falls and Plant 2 is about one-quarter mile
downstream of the falls. Plant 1 has pelton turbines; the number of turbines was not
reported. Plant 2 has two generating units. The type of turbines that are in Plant 2 was not
reported. No specifics were provided with respect to flow levels or generating capacity.

BIOLOGICAL CHARACTERISTICS:

The Snoqualmie River supports Pacific salmon (chinook and coho salmon, others not
reported but may occur) and steelhead trout populations.

PROJECT EFFECTS ON UPSTREAM FISH PASSAGE:

There is potential injury and mortality of upstream migrants that can enter the draft tubes
of Plant 2 under certain generating conditions. Fish injury and mortality to upstream
migrants is not a concern at Plant 1 because there is a 15-foot drop from the turbines to the
tailwater elevation. However, there was no mention whether fish could be injured or killed
from contacts with walls and structures in the Plant 1 draft tubes. It was concluded as a
result of tailrace survey studies that upstream migrants were not being injured or killed in
the draft tubes of the Snoqualmie Falls Project Plant 2.

TAILRACE BARRIER DESIGN: N/A
BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A
TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A

Page 56 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

Northeast Utilities Service Company. 1985. The movements and behavior of migratory
American shad (Alosa sapidissima) in the Turners Falls Project Power Canal, Turners Falls,
Massachusetts. Northeast Utilities Service Company, Hartford, CT. 29 pages and figures
and appendix.

AMERICAN SHAD

FISHWAY ENTRANCE
MIGRATION DELAY

LOCATION OF DY:

Turners Falls Hydroelectric Station, Connecticut River, Turners Falls, Massachusetts.
PROJE! HARA RISTICS:

The Turners Falls Project consists of a dam and gatehouse at the upstream end of a power
canal (2.2 miles in length) and powerhouse at the downstream end of the canal. There are
three fish ladders at the project. The first fish ladder encountered by upstream migrants is
an Ice Harbor type pool and weir ladder located at the powerhouse and allows fish to move
upstream into the canal. Another Ice Harbor type ladder is located at the base of the dam
adjacent to the power canal and gatehouse. Fish ascending this ladder enter directly into
the project impoundment. The third ladder is a vertical slot fish ladder and is located at
the gatehouse on the opposite side of the canal from where the spillway ladder is located.
The gatehouse fish ladder allows fish that entered the canal through the powerhouse ladder
to continue upstream into the project impoundment. During low water level periods nearly
all the river flow will be diverted into the canal so most fish will ascend the powerhouse
ladder into the canal.

BIOLOGICAL CHARACTERISTICS:

Adults of four anadromous fish species migrate to spawning areas located upstream of the
Turners Falls Project. Species include Atlantic salmon, American shad, blueback herring,
and sea lamprey. Because American shad passage at Turners Falls was the focus of this
report, the passage and population characteristics of the other three species are not
described. American shad are a target species included in the Connecticut River
anadromous fish restoration program. One purpose of the Turners Falls fish passage
facilities, which began operating in 1980, is to allow American shad to reach historic
spawning areas upstream of the project.

Page 80 Impacts of Hydroelectric Plant Tailraces on Fish Passage
pac!


BYPASS WATER ELEVATION

——_—q
WNWINIW .OF

FIGURE 3-6
AMBERSEN OR
BUTTRESS-TYPE

BARRIER DAM
TAILRACE BARRIER STUDY

Page 25

SOURCE: MODIFIED FROM NMFS 1993

TAILWATER ELEVATION

PRP PPP PDD DAA metre

Impacts of Hydroelectric Plant Tailraces on Fish Passage


1.0 INTRODUCTION

A tailrace is an area of turbulent
flow at the discharge of a hydroelectric
facility turbine. Tailraces can have
adverse effects on the upstream migration
of fish that live in the sea but spawn in
freshwater (anadromous) and fish that live
in freshwater but spawn in the sea
(catadromous). Other fish species spend
their entire life in freshwater and make
long migratory movements. We will refer
to all these groups of fish as migratory in
this report.

There are other areas associated
with hydroelectric facilities that have
hydraulic characteristics similar to turbine
discharge tailraces. These areas, which
may mimic tailrace effects, include:

1) spillway discharges;
2) trash sluices; and
3) fishway entrances.

The creation of impoundments at
hydroelectric facilities alters the hydraulics
of some river systems such that tailraces
may be the only areas of flowing water.
Migrating fish, particularly anadromous
fish returning to their natal waters to
spawn, are attracted to point discharges
where flow quantities are relatively large
or velocities are high. Water quality (e.g.,
desirable water temperatures) also may
attract fish to these areas (NMFS 1993).

The artificial hydraulic conditions
created by the layout of hydroelectric
facilities may attract fish away from
appropriate passage routes. Fish that are

attracted to these areas may be either
significantly delayed in their upstream
passage or diverted away from fish
passage facilities such as fish ladder
entrances.  Tailraces associated with
turbine discharges also may attract
migrants to draft tubes where they may be
injured or killed by contact with physical
structures and turbine runners or by
exposure to hydrodynamic shear forces
near the turbine runner.

All fish species may be affected by
tailraces, but most research on tailrace
attraction focuses on salmonids, and the
majority of the literature is about
anadromous species.

This report identifies tailrace
characteristics that may affect migratory
fish and summarizes impacts on these
resources. Section 2 presents the methods
used to gather the information for this
report, and a technical summary of the
Tesults is provided in Section 3. Section 4
presents a discussion on guidelines and
criteria for assessing the need for tailrace
barriers, modified project operation, or
spill regimes at project sites. Section 5
presents conclusions, and Appendix A
contains an annotated bibliography. It
also identifies potential solutions and
mitigation measures for reducing impacts.

2.0 METHODS

A literature search and a survey
questionnaire were used to gather data on
tailraces. A thorough review of the open
literature was conducted. Data were
gathered on the nature of tailraces (e.g.,
physical hydraulic characteristics that
attract fish) and direct and indirect effects

Impacts of Hydroelectric Plant Tailraces on Fish Passage

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CONTENTS

LIST OF FIGURES

Figure 3-1 Horizontal Diffuser Rack ....... 0... ccc ccc eee eee ene eee nee 18
Figure 3-2 Vertical or Inclined Diffuser Barrier ........... 0.0 ce eee ee eee eee 19
Figure 3-3 Floating Weir... 2.0... . ccc ccc een ene e eens 20
Figure 3-4 Hydraulically Operated Weir ........ 6... c cece eee eee e eens 21
Figure 3-5 Pneumatically Operated Weir ........ 600 c eee e eee eee eee eee 22
Figure 3-6 Ambersen or Buttress-Type Barrier Dam .......... 6.00 ceeeeeee 25
Figure 3-7 Velocity Barrier... 1.0... ccc cc cee nent e eens 26
LIST OF TABLES

Table 4-1. Summary of Tailrace Barrier Project Information ...............4.. 35

Page viii Impacts of Hydroelectric Plant Tailraces on Fish Passage


effectively reduces injury and mortality to
Pacific salmon. Screens at Peshtigo River,
Wisconsin, also have been effective in
protecting lake sturgeon and adult
salmonids. A berm passageway was
installed at Sultan, Sultan River,
Washington, and is reported to be
successful in reducing migration delay for
Pacific salmon and steelhead trout. There
are no reported data on the effectiveness
of the bar racks in place.

Protection, primarily in the form of
bar racks, is proposed at an additional five
sites.

One site (North Fork, Clackamas
River, Oregon) presently uses modified
generation as mitigation for injury,
mortality, and migration delay of Pacific
salmon, steelhead, and resident trout. The
modified generation schedule has reduced
injury and mortality but also has reduced
the operator flexibility in loading the units.

At eight sites, resource agencies
have requested or required mitigation that
consists of physical and velocity barriers
such as floating weirs, upwelling systems,
bar racks, and generation shut-down. At
two sites, no mitigation is proposed or
required at this time. At one of these two
sites, Bull Run, Sandy River, Oregon,
tailrace attraction is complicated by
another diversion project. At the other
site, Snoqualmie Falls, Washington, a 1993
study (Beak Consultants, Inc. 1993)
showed that suspected tailrace mortality
did not occur. Resource agencies still
suspect that the geometry of the draft
tubes and hydrology may injure fish.

Studies, which have been
performed at only 5 of the 24 sites,
include radio-tracking (2), biological
evaluations (2), and one hydraulic study of
the relationship between spill and passage.
As previously noted, the majority of target
species are Pacific salmonids.

4.2 Additional Studies

Site-specific injuries and migration
delays identified in the literature survey
indicate that additional studies may be
needed to determine the most appropriate
mitigation for a project. Some issues may
be difficult to address even with additional
study. This section identifies types of
studies that may be useful in identifying
tailrace-influenced injury and migration
delay and in developing the most
appropriate mitigation.

Both biological and hydraulic
studies may be used to acquire the
necessary information for target species
and physical conditions in the tailrace.
Biological studies can help determine
migratory fish presence, incidence of
injury, duration of delay, and population
impacts. Hydraulics studies can provide
data on tailrace velocity conditions and
fishway and bypass passage conditions.

4.2.1 Biological Studies

The most important biological issue
requiring more study is presence of
migratory or resident fish and
identification of delayed migration in the
tailwaters. In some cases, the presence of
these species may be poorly documented.

Page 34

Impacts of Hydroelectric Plant Tailraces on Fish Passage


lower recruitment levels. Alternatively, if
recruitment is related to environmental
factors (i.e. survival of young after
hatching and up to recruitment to the
spawning population), a reduced number
of spawners may not directly influence
recruitment levels. If the number of
spawners is low such that the maximum
number of young produced would be far
below the carrying capacity of the
environment, however, then spawning
stock size could strongly influence
recruitment levels.

3.1.3 Summary of Tailrace Effects

Most hydroelectric sites have the
potential to cause injury or mortality to
migratory and resident fish that move into
tailrace and draft tube areas. Tailrace-
related injury and mortality are a
particular concern for species with strong
swimming capabilities or particular
migratory behavior (i.e., the need to move
to upstream areas for spawning, feeding,
or rearing) and at sites with variable
operating conditions. The extent of
impact and the need for mitigation
measures depend on biological factors and
physical characteristics at each site.

Potential for adverse impact is
greatest at sites with adult migratory
species that are capable of negotiating
high water velocities. Migrating salmonids
are particularly susceptible to attraction to
tailrace areas, and few projects have
discharge velocities that would exceed the
swimming speeds of adult salmonids at all
operating loads. Clupeids, however, may
be less susceptible than salmonids to draft
tube and turbine runner injury and
mortality. Unlike salmonids, they typically

avoid highly turbulent areas such as
turbine discharges and generally are
unable to negotiate areas with high water
velocities greater than 15 fps (Bell 1990).

There is also potential for tailrace
effects to cause injury or death of any fish
with strong swimming capabilities (e.g.,
freshwater basses, walleye, pike, catfishes,
paddlefish, and sturgeons). Few data,
however, document effects on these
species.

Project layout, local hydraulic
conditions, and operating schedules
influence potential for injury and mortality
in tailrace and draft tube areas. In
tailraces where fish entry is unavoidable,
fishway entrances should be appropriately
located with optimum hydraulic conditions
that minimize residence of migrants in
spillway flows and turbine discharges. A
spillway flow with hydraulic characteristics
that are more attractive than the
powerhouse flows should prevent migrants
from entering most discharges and
tailraces. Discharge velocities in excess of
20 fps across the entire draft tube opening
should exclude the entry of any fish if the
length of the high velocity channel is long
enough for the target species.

To successfully identify or predict
migrant injury and mortality related to a
hydroelectric project, all relevant
biological and hydraulic characteristics at
a site must be understood. Hydraulic
conditions are often complex and difficult
to characterize. Even if fish are not being
directly injured in tailrace and draft tube
areas, there may be adverse impacts from
migration delays.

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 13


and stressed or killed by lack of water,
high temperatures, or poor water quality.

Supersaturation of nitrogen in
tailrace or spillway flow can cause
noncontact injury or death for upstream
migrants. On the Columbia River in the
late 1960s, nitrogen concentration levels
downstream of project spillways often
exceeded safe threshold levels (greater
than 120 percent saturation) for adult
salmonids (Ebel 1969; Beiningen and Ebel
1970). In 1968, upstream migrant
mortality below John Day Dam was
attributed to nitrogen supersaturation that
was produced by spill over the dam
(Beiningen and Ebel 1970). The effects of
nitrogen supersaturation (i.e., injury and
mortality) were exacerbated by delays in
fish passage at the dam. Spill deflectors
that were installed at Columbia River
dams reduced nitrogen concentration
levels and related fishery impacts.
Nitrogen supersaturation has not been an
issue in the tailraces of Columbia River
projects until this year (1994). The need
for greater flow releases to improve fish
passage has been challenged by those
concerned about the impacts of nitrogen
supersaturation.

Migrating Atlantic salmon and
American eels were injured and killed as
a result of gas supersaturation (nitrogen
and oxygen) in the tailrace of the
Mactaquac Hydroelectric Project on the
Saint John River in New Brunswick
(MacDonald and Hyatt 1973). An
investigation of gas bubble disease injury
and mortality downstream of the project
found that gas supersaturation was
produced from air vented into the turbines
at low generating levels to reduce negative

pressures. This study and the problems
experienced at mainstem Columbia River
projects, indicate that supersaturation of
atmospheric gases downstream of a dam
or powerhouse may adversely impact
upstream migrants. However, structural
or operational modifications (such as
those implemented on the Columbia
River) should alleviate such impacts.

3.12 Migration Delays

Migration may be delayed when
tailrace flows successfully compete with
river bypass reaches or  fishways.
Migration delays caused by tailrace effects
may have a greater impact on fish
populations than injury and mortality.

Migration delays can expose
upstream migrants to unfavorable
environmental stresses (high temperatures
and low flows) including predation and
poaching. Migration delay may also
increase potential for injury as fish
attempt to move into the tailrace. There
may be delay-related mortality before
spawning because of accumulated stresses
from lengthy migrations in an altered
environment or from loss of energy
reserves needed to reach spawning areas.
Because spawning seasons are finite,
delayed fish also may never reach
spawning areas and may select suboptimal
habitats for egg deposition and
fertilization or may not spawn at all.

Migration delays are well
documented for anadromous salmonids in
the Pacific Northwest (Department of
Fisheries, Canada 1958, 1962; IPSFC 1976;
Haynes and Gray 1980; Rondorf et al.
1983; Schadt et al. 1985; Vogel et al. 1990;

Page 8

Impacts of Hydroelectric Plant Tailraces on Fish Passage


EXECUTIVE SUMMARY

Fish injury, mortality, and migration
delay are associated with some
hydroelectric project tailraces. This report
reviews the extent of these issues and
identifies tailrace characteristics that may
affect fish.

Little scientific information exists
on these topics. To collect information
for this report, we conducted a
computerized literature search and a
telephone survey of fisheries agencies, and
we sent a survey questionnaire to
hydroelectric projects where  tailrace
barriers are installed or proposed. We
requested information on site conditions
and cost and effectiveness of tailrace
barriers. Based on survey results, we offer
conclusions about tailrace effects on
populations, causes of injury and delay,
and use and effectiveness of tailrace
barriers. Importantly, we also obtained
sufficient information from the surveys to
provide guidance for reviewing license
applications and agency recommendations
involving tailrace barriers.

None of the information collected
quantified the effects of tailrace delays on
migratory fish population _ levels.
Migration delays can, however, limit the
upstream extent of migration, and delays
of as little as 3 days may have critical
effects on the spawning success of a
population. Delays can cause migrants to
spawn in suboptimal habitat or to abandon
spawning. Delays can cause mortality by
reducing energy reserves of migrating fish.

Tailrace-related injury can be
caused by both biological and physical

conditions. Swimming speed of a fish
influences its ability to enter dangerous
areas of the tailrace. Turbine elevation,
exit velocities, and turbine type influence
susceptibility of fish to injury in the
tailrace. Fish are injured when they
contact the turbine runner, walls of
tailrace structures, or hydraulic shear in
the draft tube. Fish also can be injured
from water quality related impacts of
hydropower operation (e.g., nitrogen
supersaturation). Secondary infection of
injured fish can lead to delayed mortality
and lowered reproductive success.

Upstream migrants can be delayed
when stream scents and hydraulic
conditions attract migrants to impassable
tailrace flow discharges. Inadequate
fishway entrance conditions also can delay
fish passage.

Limited data are available on the
effectiveness and use of tailrace barriers;
our survey identified only 22 sites with
useful information about bar racks,
screens, netting, and other guidance
devices for migrants.

Tailrace barriers can be used to
repel migrants from undesirable passage
routes and guide fish to ladders or
preferred routes of migration. Horizontal
diffuser barriers physically block migrants
without inducing fish to jump. Vertical
diffuser barriers with low differential head
can be equally effective. Height and
water velocity can be used to block or
guide fish passage at barrier dams.
Electric fields also have successfully been
used to block upstream passage. Sound

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page v


Annotated Bibliography

of a reservoir. Although the barrier was not used for a hydroelectric application, it does
appear that this type of barrier could effectively exclude fish from entering a tailrace area
at a powerhouse. The feasibility of this type of fish barrier for hydroelectric applications
most likely would be site-specific. It appears the barrier has the potential to effectively
exclude a wide range of fish species based on its ability to prevent seven species of rough
fish from upstream areas during the study conducted on the Roaring River. No information
was provided with respect to the size of fish that were excluded by the barrier; however, fish
that may be small enough to pass through this type of barrier typically would not be a
concern at powerhouse tailraces.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 63


LOW TAILWATER
ELEVATION

POWERHOUSE
STRUCTURE

a

FUSER SCREEN

ol
a af o
SS a |
1
; aot
DRAFT TUBE \ — SEES
' SS
i aK
1
ECSSESIEEEECEEEREEEESEEEEE SEE
FIGURE 3-1
HORIZONTAL DIFFUSER

RACK

TAILRACE BARRIER STUDY
SOURCE: MODIFIED FROM IMES 1999

Page 18 Impacts of Hydroelectric Plant Tailraces on Fish Passage


subsequent late or non-arrival at spawning
grounds. ‘

3.1.1 Injury and Mortality

Migrants that are attracted to
turbine discharges or other tailrace-like
areas may be injured when they attempt to
ascend draft tubes or other areas not
intended for passage. Lacerations and
abrasions from these attempts may result
in direct or delayed mortality.

Physical and biological factors
influence potential injury and mortality.
Physical factors include draft tube velocity,
turbine design, elevation relative to
tailwater, proximity to concrete walls,
presence of rocks or obstructions in the
tailrace, and variable operating conditions.
Biological factors include species, life
stages, size, and swimming ability.
Different species have different swimming
capabilities (duration and speed of
movement) that influence the potential for
injury and mortality at a project. Project
design and operation govern the physical
factors that affect injury and mortality.
The types of injury sustained are often
related to a combination of the swimming
ability of the species and the turbine
design.

This factor has a species-specific
impact. For example, where both species
occur, salmonids, with their stronger
swimming capabilities, are more likely
than clupeids to ascend draft tubes during
periods of high project flows. This
increases the salmonids’ risk of injury or
mortality.

Fish swimming capabilities strongly
influence potential injury and mortality in
powerhouse draft tubes. Fish swimming
speed and stamina, combined with draft
tube length and minimum discharge flow
velocity, determine the ability of a fish to
ascend a draft tube. Some draft tubes
may have water velocities that can be
negotiated by fish, but, if the draft tube is
too long, fish may not be able to sustain
enough speed to reach the turbine
runners, Fish also may expend a great
deal of energy attempting to ascend these
areas and then lose valuable energy
reserves. Loss of these reserves then
could result in death or poor condition
before spawning.

At sites with high discharge
velocities (such as typical draft tube
discharges) fish use their maximum
swimming effort (burst speed) when
attempting to ascend these flows. Burst
speeds, which cannot be maintained for
more than a few seconds and cannot be
repeated without a period of recovery, are
directly related to fish length and species
type (Hildebrand et al. 1980). Larger fish,
therefore, are more likely to enter draft
tubes than smaller fish and are more
susceptible to injury and mortality. If
discharge water velocities are low,
however, fish could enter draft tubes with
steady or sustained swimming speeds,
depending on water temperature and
oxygen levels (Hildebrand et al. 1980).
Fish could also enter the draft tubes
during unit shut-down if leakage water
attracts fish.

At projects where there are adult
salmonids, water velocities less than 16
feet per second (fps) may not exclude

Page 4

Impacts of Hydroelectric Plant Tailraces on Fish Passage


1 fps equate to a head differential of less
than 0.2 feet and should have a minor
effect on power generation.

Jumping-related injuries and
mortality have been observed at the Roza
Hydroelectric Project on the Yakima
River in Washington (NMFS 1993). Fish
diverted from the mainstem river into the
water wasteway are delayed because the
wasteway is a dead end (i.e., there are no
upstream fish passage facilities). To
reduce false attraction to the wasteway, a
bar rack diffuser barrier was constructed
at the confluence of the wasteway and the
river. The Roza barrier also was designed
to inhibit fish jumping at the rack.

Barrier screens can be located
downstream of debris sluices and tailraces
or flush against powerhouse draft tube
exits to reduce injuries. A barrier screen
called a "fish guard gate" was installed at
one of the turbine discharges at the
Peshtigo Hydroelectric Project, Peshtigo
River, Wisconsin (Krueger 1989). The
fish guard gate was installed to prevent
lake sturgeon and adult salmonids from
entering the draft tube where they were
being injured and killed. The barrier
screen at Peshtigo has panels of steel bars
set horizontally in a large frame and
supported by larger vertical bars. The
entire gate structure is set flush to the
powerhouse at the turbine outfall. The
panels can be rotated to a position
parallel to the flow for maintenance. The
spacing between horizontal bars is
adequate for blocking the movement of
the target species into the draft tube.

Non-Diffuser Barrier Dams

Barrier dams are a_ hydraulic
barrier that uses height or velocity to
block migration. Barrier dams are the
most common non-diffuser barrier used to
block fish entry into tailraces and draft
tubes and to guide migrants to fishway
entrances or a bypass channel. They
should be designed to block movement of
target species and to minimize potential
injury and reductions in power generation.

Barrier dams are similar to barrier
screens. They should be angled and
designed to terminate upstream at a
fishway or bypass channel entrance, which
facilitates migration past a project by
directing fish to locate upstream passage
routes.

Barrier dams are usually one of the
following types: (1) Ambersen or buttress;
(2) velocity barrier; or (3) porous dams or
dikes (e.g., rock dams or gabion diffusers).
Buttress-type and velocity barriers are
classified as hydraulic barriers because
they create hydraulic conditions that
cannot be ascended by fish. Hydraulic
barriers usually are used at sites with
upstream adult salmonid migrants because
most salmonids can swim at high speeds
and jump considerable heights. Porous
dams allow water but not fish (depending
on size class) to pass through the
structure, physically preventing fish from
moving upstream. Because porous dams
usually are designed to function without
spill, they are appropriate for blocking
movement of most adult fish. Also,
porous dams act as a diffuser (similar to
barrier screens) creating low water
velocities that are unattractive to migrants.

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 23


Annotated Bibliography

Vande Sande, T. 1982. Potential impacts of hydropower development on upstream fish
passage. In: 1982 Northeast Coldwater Workshop June 15-17, 1982-Ithaca New York;
Hydropower Development and Fisheries Impacts and Opportunities. pp 37-44. New York
State Department of Conservation. 127 pages.

KEYWORDS

UPSTREAM FISH PASSAGE

MIGRATION DELAY
HYDROPOWER IMPACTS

LOCATION OF STUDY: N/A
PROJECT CHARACTERISTICS: N/A
BIOLOGICAL CHARACTERISTICS: N/A

ECT EFFECTS ON UP: E: N/A
TAILRACE BARRIER DESIGN: N/A
BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A
TAILRACE BARRIER EFFECTS ON PROJECT OPERATION: N/A
COMMENTS:

The impacts of hydropower on upstream fish passage are summarized and several important
factors that influence migration delays and spawning success are discussed. The study states
that passage success in controlled flow conditions (e.g., hydropower projects) should reach
100%. The author suggested that to determine passage delays and its effects, the following
information should be obtained: 1) total number of days fish could not pass (i.e.,
unfavorable flow conditions); 2) consecutive number of days fish could not pass; 3) number
of days fish were present for passage; and 4) the effect of delay on spawning success. Also,
available flow data should be incorporated into evaluations of passage delays. The author
recommended the use of fish barriers (e.g., barrier dams, picketed fences, and electric
fences) when more water is discharged from a powerhouse than from fishway channels or
entrances. It was noted that power plants that operate under peaking schedules may cause
additional delays for upstream migrants, and high discharge flows during power generation
periods can mask fishway attraction flows. Major fluctuations in flow levels from peaking
operations can interrupt migrations throughout a river reach below a powerhouse. Reduced

Page 92 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

BI GI F TAIL! E BARRIER:

As part of a lamprey eradication program, the barrier was evaluated for its ability to prevent
sea lamprey from reaching upstream spawning areas without harming spent steelhead trout
passing downstream. With the voltage gradient described above, the electrical barrier
successfully blocked all upstream migrants and passed downstream-migrating steelhead trout
without injury or mortality. Also, it was determined that no injury or mortality occurred to
steelhead trout smolts that migrate downstream at the same time as adult lamprey and
steelhead migrate upstream.

‘AIL FFE IN_PROJE : N/A
COMMENTS:

The electrical barrier evaluated on the Pere Marquette River blocked upstream movements
of adult sea lamprey. The barrier achieved the objective of blocking lamprey movements
to upstream spawning areas without harming steelhead trout adults and smolts. These
results show that electric barriers may effectively be used in hydroelectric applications as
tailrace barriers.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 85


migrants from ascending a draft tube.
Steelhead trout and chinook salmon are
able to negotiate the entire length of an
85 foot channel at water velocities of 13.4
and 15.8 fps (Weaver 1963). Clupeids also
may be able to swim upstream against
velocities greater than 10 fps. Adult
American shad are able to swim moderate
distances (less than 75 feet) in water
velocities up to 14 fps (Weaver 1963).

Swimming capabilities also may
vary among individuals of the same
species, depending on location in the river
and how ready the fish is to spawn
(gamete maturation stage). During a
study conducted with Fraser and
Thompson River pink salmon, gravid
(ready to spawn) fish had greater
swimming strength than spawning fish, and
spawning fish had greater swimming
strength than fish that had already
spawned (Williams and Brett 1987).
Williams and Brett also found that pink
salmon that were collected lower in the
Fraser River were stronger swimmers than
those collected at upriver spawning sites.
This suggests that lower basin projects
may have more problems with fish
entering draft tubes because fish are
generally stronger swimmers at lower
points in a river basin.

Design an ion

Physical factors such as project
design and operation influence potential
injury or mortality. Physical factors that
may affect powerhouse-related damage
include: turbine type, draft tube design,
tailwater elevation, and discharge flow and
velocity.

Although type of turbine may affect
fish injury and mortality, discharge
velocities have more influence on whether
or not fish are able to move into a draft
tube and subsequently approach shear
zones or turbine runners. Because turbine
discharge velocities typically do not exceed
the upper range of adult salmonid
swimming speeds, there is potential for
draft-tube-related injury and mortality at
most hydroelectric sites where there are
migratory salmonids.

Even if discharge water velocities at
full load operation would prevent fish
from ascending a draft tube, low velocities
during partial operation may allow fish to
enter. There may be partial load
operation during prolonged shut-down or
start-up, while a unit is on spinning
reserve, or during low-flow periods. Fish
also may enter draft tubes during non-
generation periods and then be injured or
killed during turbine start-up.

Water velocity in draft tubes can be
highly variable in space and time. Draft
tubes can have significant variability in
distribution of high and low velocities.
Low velocity areas may allow fish to enter
a draft tube with a high average discharge
velocity. During start-up and shut-down,
velocity distributions vary with rapidly
changing flows. These shifting velocity
patterns may induce fish to swim at burst
speed toward and into turbine runners.
Fish injured in this manner generally drop
to the tailrace and are undetected (NMFS
1993).

Many projects have draft tubes with
a 90° elbow and multiple tailrace
openings for a single unit. These multiple

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 5


Annotated Bibliography

BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A
E BARRIE) IN_PR PERATION: N/A
COMMENTS:

This study demonstrates the effects that a hydropower project can have on the upstream
migration of a juvenile life stage. The Trevallyn Station blocked upstream movements of
elvers at all generating levels and prevented trapping of upstream migrants at high turbine
outputs because elvers were unable to negotiate the high flow velocities.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 91


Annotated Bibliography

Wagner, C. H. 1967. Fish barrier dams. Fish Facilities Section, Columbia Fisheries
Program Office, Bureau of Commercial Fisheries. Portland, OR. 9 pages.

PACIFIC SALMON
AMBERSEN-TYPE

LOCATION OF STUDY: N/A

PROJECT CI RI ; N/A

BIOLOGICAL CHARACTERISTICS: N/A
PROJECT EFFECTS ON UPSTREAM FISH PASSAGE: N/A
TAILRACE BARRIER DESIGN:

This paper discussed two fish barriers designed to guide fish. One design, an Ambursen-
type dam, is based on a water level drop that is sufficient for preventing upstream
movement of fish at all flow levels. The other design prevents fish passing upstream by
producing shallow depths with high flow velocities on an apron structure that has a flow
direction change at the upper end. Proper placement of the barriers and fishway entrances
and modification of river channels (where necessary) were considered important to the fish
guidance effectiveness of both barrier designs.

The Ambursen-type barrier is a structure that is angled upward in the downstream direction.
A channel is produced behind turbine discharge water that falls over the barrier.
Depending on the site, the channel can be connected to a side entrance of a fishway.
Upstream migrants either swim or fall into the channel as they try to jump over the barrier.
Directional flow through the channel can be produced from a side entrance of a fishway or
if one end of the channel is set at lower tailwater level than the other end. A minimum of
10 feet of head was considered necessary; however, 8 feet of head may be sufficient for
some anadromous salmonid species (i.e., barrier effectiveness depends on a species’
swimming speed and jumping capabilities). Barriers of this type have been constructed at
the Klamath River Fishway, Baker River Project, Mayfield Dam, and Cowlitz River salmon
hatchery. Adjustable weirs and electric barriers have been used at sites where hydraulic
conditions reduced the effectiveness of a Ambursen-type barrier dam.

The second type of barrier requires high water velocities (minimum of 16 fps) to prevent
fish from ascending the apron of the barrier. Also, the water depth along the apron must

Page 96 Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

COMMENTS:

This study examined dissolved nitrogen concentration below hydroelectric projects on the
Columbia River mainstem (lower 640 km) and assessed the effects of the dissolved nitrogen
levels on upstream migrants. Due to heavy spills, the nitrogen concentrations immediately
downstream of the dam were high (exceeded 120 percent). Gas supersaturation-related
mortality (i.e., gas bubble disease) of adult salmonids was observed below the John Day
Dam; specifically, during delays in migration that were caused by inadequate fishway
attraction flows. Also, many fish that did pass through the fishways exhibited external
injuries characteristic of gas bubble disease. Based on the results of this study, it was
concluded that high nitrogen concentrations (in excess of 125 percent saturation) were
partially responsible for mortalities of adult upstream migrants downstream of the John Day
Dam. Additionally, it was determined that delays caused by sub-optimal fishway attraction
flows contributed to the mortality associated with gas supersaturation. The results of this
paper demonstrate secondary negative impacts that may occur to upstream migrants when
they are delayed at a hydropower project. When fish are delayed at hydroelectric projects,
they may be exposed to changing environmental conditions (gas concentrations and
temperature regimes). These conditions may lead to increased stress levels that result in
mortality or reduced spawning success due to poor physical condition.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 59


Annotated Bibliography

Clay, C. H. 1961. Design of fishways and other fish facilities. Department of Fisheries of
Canada, Queen’s Printer, Ottawa. 301 pages.

FISH LADDER DESIGN

BARRIER DAMS
FISHWAY ENTRANCES

LOCATION OF STUDY: N/A

PROJECT CHARACTERISTICS: N/A

I ICAL CHARACTERISTICS: N/A

PR EFFE! IN UPSTREAM FISH PASSAGE: N/A

TAILRACE BARRIER DESIGN: N/A

BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A
‘AIL EFFECTS PROJE! PERATION: N/A
MME!

This book provides comprehensive information on the design and application of fishways.
The author discusses the biological and engineering aspects of fish ladders, locks, elevators,
fences and barrier dams, screens, and artificial spawning channels. Two sections from this
book are particularly relevant to the effects of tailraces and associated structures on
upstream fish passage. The first relevant section discusses fishway entrances and the second
provides information on fish barriers. The author cites fishway entrance locations as the
most important aspect of a fish ladder because improper placement may lead to
considerable migration delays or complete cessation of upstream movement, if fish cannot
locate the entrance or are unwilling to enter it due to local hydraulic conditions.
Additionally, it was stated that the physical changes in a fishes environment, other than
blocked migration, that are produced by dams contribute to stress levels beyond the effects
of delayed migration. These physical changes may include alterations in temperature and
flow regimes (velocity and volume).

The author concludes that if a fishway is to be effective, there should be no delay in
passage. To reduce potential delays at fishways located adjacent to spillways (i.e., at either
end of the spillway), it was recommended that spill gates be opened from the center of the

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 65


provide fishway entrances both at the
tailrace and at the head of the bypass
reach. Depending on the site, migrants
may be attracted to hydraulic conditions in
the tailrace (Department of Fisheries,
Canada 1958, 1962; Schadt et al. 1985;
PacifiCorp 1993; IPSFC 1976). Bypass
reach water temperatures may be
unattractive to upstream migrants due to
low flows and extremes in atmospheric
conditions. Increases in bypass reach
flows or decreases in powerhouse flows
may reduce attraction of migrants to
tailrace areas. This type of flow control
may not be necessary at projects that have
upstream fishway entrances at the
powerhouse and spillway.

Some powerhouses are located a
considerable distance from the river, and
their design includes wasteways to spill
unneeded water or to pass debris back to
the river channel. These wasteway
channels are dead ends to upstream fish
passage. At the Roza and Leaburg/
Walterville projects, barriers were
constructed at the confluence of the
wasteway channel with the river to
minimize this potential impact.

Inadequate Fishway Entrances

The ability of fish to locate or enter
fishways depends on entrance design and
location and the presence of competing
flows. If fishway entrances do not provide
adequate flow and velocity at the proper
location, migrants may be reluctant to
enter them, even in the absence of
competing flows. It also is possible for a
fishway to attract fish despite higher
velocities at adjacent spillways or draft
tubes if the fishway entrance is properly

located with adequate entrance water
velocities. The most effective fishway
entrances are sited based on fish
behavioral response to tailrace conditions.
Multiple entrances may be required to
cater to a range of flows.

To reduce false attraction, fishway
attraction flow should be at least 3 percent
of adjacent powerhouse or spillway
discharges when a fishway is located along
the shoreline (Hildebrand et al. 1980).
For small hydroelectric projects,
Hildebrand et al. (1980) recommend
attraction flows that are 3 percent of the
average annual river flow at the project.
For a number of sites that pass Pacific
salmonids, fishway flows are 4 to 10
percent of the total project flows (Bates
1992). Where possible, project operation
and spillway flow distribution should
alleviate false attraction and consequent
migration delays.

A poorly designed or located
fishway can inhibit fish passage at
hydroelectric dams. Other factors that can
influence fishway attraction include
lighting, flow patterns, channel shape and
size, and availability of holding areas.
Although a fishway may be properly
designed and sited for the behavioral and
physical characteristics of targeted fish
species and for local hydraulic conditions,
migration still may be delayed if
powerhouse or spillway flows mask fishway
entrance attraction water. Such delays can
be alleviated by manipulating generation
levels and the amount or distribution of
spill over a dam. The most efficient
fishway entrances are located based on
site-specific assessment of migrating fish
aggregations in the tailrace.

Page 10

Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

oxygen levels due to organic waste assimilation at low water levels also may impede
upstream fish movement. At projects with reservoirs, there may be more potential for low
oxygen levels downstream of the plant. Reservoir discharges with high water temperatures
were implicated in pre-spawning mortality and reduced spawning success of fall run salmon
in some California rivers.

Spill over a dam also was cited as a source of passage delay. To allow fishway attraction
water to be detected by upstream migrants, it was suggested that the majority of spill at a
dam be released as far away from fishway entrances as possible to allow the fishway
attraction water to be detected by upstream migrants. If there are fishways on both river
banks, the spill should be concentrated at the center of the dam. Also, large volumes of
water spilled over a dam can produce supersaturation of atmospheric gases, which can lead
to fish mortalities at levels greater than 120 percent saturation.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 93


fishway entrances or a bypass reach may
be necessary.

Regardless of the impact type, all
site-specific biological, physical, and
hydraulic parameters must be considered
when formulating appropriate measures to
reduce injury or migration delays.

Migration delays at many projects
can be reduced through improved fishway
entrance design, flow characteristics, or
location. Fishway entrance design and
location may be the most important
aspects of successful fish passage at
powerhouses and dams (Clay 1961).
Although some delay in migration may be
inevitable at hydroelectric projects,
properly designed and constructed fish
passage facilities minimize delays and
subsequent impacts.

Before selecting appropriate
mitigative measures to reduce or prevent
negative impacts to fish passage at a
hydroelectric project, specific issues must
be identified. If injury, mortality, or
migration delays result from tailrace
attraction, then a barrier that blocks
movements into tailraces and guides fish
to fishway entrances or a bypass reach
may be required. A barrier that
completely blocks upstream movement
may be sufficient, however, at projects
where fish injury and mortality are the
only concern. At sites with only migration
delay problems, measures to guide fish to
passage routes will be needed.

Appropriate mitigation for impacts
on upstream migrants must consider a
design that will not have an impact on
downstream migrants. Downstream

migrants may pass existing spillways or
turbines with some success. Some tailrace
barrier designs may lead to impingement
or injury from plunging into a concrete sill
or striking fixed structures on the tailrace
barrier. Downstream migrating juvenile
salmonids were observed to be impinged
on the rectangular bar rack tailrace
barrier at the Weber Dam on the Grand
River in Lansing, Michigan (Whelan
1994),

Downstream migrants can also be
affected by predators that populate
tailrace habitats. Downstream migrants
that successfully pass turbine or spillway
flows are often prey for tailrace predators.
Tailrace barriers for upstream migrants
would not be expected to contribute to
this effect.

After the problem is defined,
mitigation (such as barriers) can be
developed based on site-specific biological,
physical, and hydraulic characteristics.
Depending on the barrier type, biological
characteristics such as swimming and
leaping capabilities of the target species
must be considered. Important physical
characteristics at a project include length
and width of a tailrace, location of
fishways, spillway size and location, water
velocities, and other physical structures
associated with the powerhouse or
tailrace. Important hydraulic conditions
that can influence tailrace barrier design
include powerhouse and spillway discharge
volume and water velocity at all operating
conditions and all headwater and tailwater
elevations.

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 15


because the bar or screen spacing is likely
to be smaller than the trash racks on the
intake of the hydroelectric facility.
Behavioral barriers may be a promising
alternative to the bar racks or screens, but
many behavioral barriers lack suitable
documentation of effectiveness at this
time. Underwater sound or lights may be
effective at repelling fish from unsuitable
passage locations. There should be
enough data on the species-specific
repellent efficacy of the device and the
ambient tailrace sound or light levels to
evaluate the feasibility of these devices for
the site.

If migration delay is a problem,
angled bar racks or diffuser dams that can
alter the hydraulic characteristics and
guide migrating fish to a ladder entrance
should be considered. Also ladder
entrance conditions and improvements to
orientation or hydraulics that could further
limit tailrace delays should be reviewed.
These types of studies can be readily
accomplished with radiotagging or
hydraulic (physical or numerical)
modeling.

A barrier dam or velocity barrier
below the powerhouse tailrace should be
considered for species which are not likely
to jump (e.g. American shad) or for
species with limited swimming ability (e.g.,
alewife and blueback herring). These
devices could reduce available head,
generation, and revenue for the project.
This should be one of the last options
considered for a turbine discharge during
the feasibility analysis because barrier
dams and velocity barriers are likely to
create permanent operational costs to the
project.

43.3 Effectiveness

The effectiveness of a feasible
tailrace barrier must be evaluated against
the fish restoration plan, watershed
management plan, or professional opinion
of the resource agencies that prompted
the need for the tailrace barrier. If the
plan specified that no more than
50 percent of the upstream migrants must
be delayed for 3 days or less, then the
expected effectiveness of the proposed
device should satisfy this requirement.
There should be sufficient data to
determine the expected effectiveness,
these data should be available from actual
experience at similar sites or should be
demonstrated with a less costly prototype
at the site. Prototype testing may also be
necessary for any innovative solutions that
lack experience-based effectiveness data.

For methods that use modified
project operation or spill as the proposed
tailrace barrier, the recommended barrier
should be accompanied with a
requirement for the licensee to monitor
the effectiveness of the system.
Monitoring may identify minor changes to
the proposed modified operation that may
improve effectiveness. Monitoring is
particularly useful for trimming overly
conservative schedule requirements for
operational spills. For example, a
monitoring study may show that the
migration season is more protracted than
identified in original data used to establish
a spill season for fish attraction. With
additional monitoring information,
mitigation probably will be less costly.

Page 44

Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

of the high velocity plume created by the berm. Should fish enter the discharge canals, it
was considered unlikely that they would contact the turbine runners because of the location
and design of the two Pelton units. The distance of the turbines from the water surface,
high water velocities, turbulent water, air depression system noise, and lack of a plunge pool
inside the discharge canals are all factors that would prevent fish from leaping and striking
the turbine runners. However, fish striking the canal walls could still be a source of fish
injury and mortality.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 89


require a minimum sill height of 3.5 feet
(Wagner 1967). Velocity barriers may be
ineffective if tailwater levels exceed the
height of the downstream end of the
apron. Similar to buttress-type barriers,
velocity barriers are used to guide
upstream migrants to a fishway entrance
or bypass channel. If a velocity barrier is
angled, a channel with directed flow can
be placed beneath the crest of the apron
overflow. The abutments of a barrier dam
must be designed for a range of flows to
prevent fish passage around the ends of
the dam.

Porous dams are physical structures
that block the upstream movement of fish
too large to swim between gaps in the
core material. River flow continues
downstream by passing through the dam
without overflow, except during high water
periods. Porous dams effectively prevent
upstream fish movement as long as there
is no overflow. Because upstream
migrations often occur during high water
periods and tailwater elevations at
hydroelectric projects can fluctuate
considerably, porous dams most likely
cannot be placed near spillways or
powerhouses. Porous dams could be used
at the downstream exit of a tailrace or
bypass reach.

A rock dam fish barrier constructed
on a tributary to the Cordell Hull
Reservoir in Tennessee _ successfully
limited passage of undesirable species
from moving upstream (Bulow et al.
1988), Although the barrier was effective,
fish were able to move upstream during
periods of high river discharge. The dam
had a negative impact, however, in that
river habitats upstream of the barrier

experienced decreased quality because of
increased sedimentation and siltation.

Behavioral and Electrical Barriers

Behavioral barriers have been
extensively examined for downstream fish
protection (EPRI 1986, 1993), but not for
upstream migration.

Two behavioral devices have
considerable potential for protecting
juvenile downstream migrants (specifically
juvenile clupeids and salmonids): strobe
lights and transducer sound systems
(Loeffelman et al. 1991; Klinect et al.
1992; EPRI 1992, 1993; Dunning et al.
1992; Nemeth and Anderson 1992; Ross et
al. 1993; RMC and Sonalysts 1993). An
underwater strobe light pulses bright,
broad frequency light at rates of
approximately 300 flashes/minute to repel
fish. Strobe lights may have upstream
applications, but further studies are
needed to determine effectiveness for
adult fish. A transducer system that uses
low-frequency sounds has been shown to
block the movement of steelhead trout
ascending a fish ladder (Loeffelman et al.
1991). However, as with strobe lights,
further studies are needed to refine sound
systems before they can be considered a
viable upstream fish barrier technology.

Electric fields are an effective
upstream fish barrier. These devices elicit
an immediate avoidance response from
approaching fish. They may also
temporarily impair a species’ swimming
ability, which allows them to be swept
downstream. Electric barriers require a
constant water velocity to sweep fish from
the electric field.

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 27


Migration Timing and Spawning
Success

Specific effects of spawning
migration delays on fish population size
are not well documented in the literature.
As shown in the following discussion,
however, there are many possible adverse
effects of migration delay on fish.

Effects of delays on migration
timing and spawning success depend
primarily on the species of fish and
environmental factors. For example,
negative impacts may be considerably
greater for populations of migratory fish
that spawn once during their life span and
die at the end of the spawning season
whether they have spawned or not. If an
entire age class of these fish is adversely
impacted, the effect may be observed over
many generations. Populations of species
capable of spawning several times during
their life span, including most clupeids,
may not be similarly affected by migration
delays but may see some proportional loss
in reproductive potential.

Some species that spawn in
multiple years also can be affected both by
the need for adults to successfully pass
downstream and by delay-related spawning
failures. Some that spawn in more than
one year of their lives spawn infrequently
(e.g., sturgeons). Other species such as
clupeids and Atlantic salmon suffer high
mortality levels after spawning, and second
time spawning frequency is low.
Therefore, a single spawning migration for
these species contributes more to their
population than to the population for a
species that spawns every year with little

mortality (typical of most resident
freshwater species).

All fish species have distinct spatial
and temporal spawning requirements.
Fixed spawning times in habitats with
annual variations in productivity have
evolved to ensure that larval fish hatch at
a time when the physical environment
(e.g., water temperature and flow) and
food supply levels are conducive to
survival (Bye 1984). Some species such as
chinook salmon hold in the river for
several months before initiating their final
upriver migration and spawning. This
provides for optimal spawning timing but
requires adults to migrate in a weak
physical condition.

Spawning habitats and time of
spawning also are important for the
survival of eggs. Without adequate
temperature and oxygen regimes, hatching
rates may be considerably reduced.
Migration delays can reduce the survival
of both eggs and larvae by causing adults
to spawn in marginal habitats or at times
when environmental factors are less than
optimal.

Most migratory fish species have
fixed spawning times. Photoperiod (length
of day) is a major influence on salmonid
reproductive cycles (de Vlaming 1972; Bye
1984). Photoperiod influences gamete
maturation in anadromous fish even when
spawning migrations are delayed. Females
that ovulate before reaching spawning
areas have lower spawning success. In a
study that examined the viability of over-
ripened ova from female rainbow trout,
egg hatching rates decreased and alevin
deformities increased with increased

Impacts of Hydroelectric Plant Tailraces on Fish Passage

Page 11


Annotated Bibliography

TAILRACE BARRIER DESIGN: N/A

BIOLOGICAL EFFECTS OF TAILRACE BARRIER: N/A
TAILRA‘ TER EFFE! IN PROJECT OPERATION: N/A
OMM.

Based on the movements of radio-tagged fish, it was determined that fish were repelled by
turbulence from the powerhouse discharge. Estimated delays of American shad at the
Hadley Falls Project ranged from 2 to 7 days. Problems also were noted with the attraction
of upstream migrants to the spillway lift. Attraction water for the spillway lift competes with
dam spill during periods of high flow. High flows are the prevailing condition for upstream
migrating shad and river herring. During low flows, all river water is diverted through the
powerhouse and canal system which results in virtually all upstream migrants being attracted
to the tailrace. To reduce delays in the tailrace, it was suggested that the entrance to the
tailrace lift collection facilities be moved downstream so that the attraction flows did not
compete with the turbine discharge. Also, it was noted that the future operation of a second
unit probably would increase delay problems. Potential for fish entering the powerhouse
draft tubes was not discussed.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 55


and light behavioral barriers may provide
alternative methods of blocking fish
passage. However, fisheries resource
agency acceptance of these methods has
been limited. Modified project operation
and spill release also have been used to
limit delay and improve passage
conditions.

This report provides guidance for
reviewing tailrace barrier recommen-
dations; guidance is a four-step evaluation
of need, feasibility, effectiveness, and cost.

.A clearly identified need can eliminate
some contentious issues and help identify
the appropriate tailrace barrier.
Biological or hydrological studies often
can provide information needed for
completing the four-step evaluation
process for tailrace barriers at a project.
Project generation and revenue also can
be influenced by head loss associated with
installing and operating barrier dams, bar
tacks, and screens.

Page vi

Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

Schadt, T. H., R. G. Metzgar, R. E. Carman, and J. H. Neuner. 1985. Background and
assessment of a berm/fish passageway designed to facilitate upstream migration past a
tailrace area. In: Symposium on Small Hydropower and Fisheries May 1-3, 1982-Aurora,
Colorado, pp 409-415. The American Fisheries Society. Bethesda, MD. 497 pages.

PACIFIC SALMONIDS
MIGRATION DELAY

UPSTREAM FISH PASSAGE
BERM/FISH PASSAGEWAY
SCREENS

LOCATION DY:
Jackson Hydroelectric Project, Sultan River, northwestern Washington.

PROJECT CHARACTERISTICS:

The Jackson Project has four turbines with a combined generating capacity of 112 MW.
Eight miles of tunnel and pipeline bring water from an upstream reservoir (Spada Lake) to
the powerhouse. Only two (Pelton turbines) of the four turbines discharge water directly
into the Sultan River and have a combined operating capacity of 1,300 cfs with a maximum
discharge velocity of 4.8 fps (average velocity is about 2.6 fps). Discharge from the other
two units (Francis turbines) moves through a pipeline that terminates upstream at a second
lake (Lake Chaplain). Spada Lake is impounded by Culmback Dam and the lake provides
water for the City of Everett. Because the Everett water supply and instream flow
requirements have precedence over power production at the Jackson Project, water is
rerouted back upstream to Lake Chaplain during periods of low flow. To meet instream
flow requirements, water is returned to the Sultan River through another pipeline. The
hydraulic head provided by Spada Lake is sufficient to transport water through the entire
system.

BIOLOGI HARA‘ RISTICS:

Anadromous species that utilize the Sultan River Basin for spawning and rearing purposes
include chum, pink, coho, and chinook salmon; steelhead and sea-run cutthroat trout; and
Dolly Varden. The primary species of concern that spawn above the Jackson Project are
fall-run chinook and summer- and winter-run steelhead trout.

Impacts of Hydroelectric Plant Tailraces on Fish Passage Page 87


wet is generally 30 to 50 percent more
costly than new project construction (Taug
1994).

3.2.4 Summary

Tailrace barriers are designed to
prevent target fish species from entering
areas where they might be injured or
delayed in their upstream passage.
Tailrace barriers are often used with fish
passage facilities, but some are also used
solely to prevent injury. The biology of
the target species, the physical and
hydraulic conditions of the tailrace, and
project operations all influence the
effectiveness of tailrace barriers.

There are two major categories of
tailrace barriers: diffuser and non-
diffuser. Diffuser barriers are typically bar
racks or barrier screens used to spread out
the tailrace velocity distribution and
physically block passage of fish. Diffuser
barriers minimize high-velocity zones to
reduce the potential of some species to
jump at cascading or high velocity flows.
The screens or bar racks are often angled
to direct migrants to a fishway entrance or
away from a location not suitable for
passage. Although diffuser barriers can
incrementally reduce operating head and
thus energy production, typical designs
should have little effect on head. Diffuser
barriers also may require periodic cleaning
to prevent debris build up, unless flow has
already been screened upstream.

Non-diffuser barriers include
barrier dams, electric fields, and
behavioral devices that use sound or light
to repel fish. Porous dams physically
exclude upstream migrating fish but allow

downstream passage of water. Buttress
dams use differential head to block
upstream passage. Buttress dams must be
higher than the height that target fish
species can jump. Velocity barriers are
low dams that create long, high-velocity
flows in the path of migrating fish. The
water velocity and hydraulic jump must be
higher than the swimming ability of the
target species. In addition, the path that
fish must swim at high velocity must be
greater than the longitudinal distance the
target species can jump.

Electric fields are a type of non-
diffuser barrier. Electric barriers with
graduated field strengths are designed to
limit injury to target species. While
effective at some sites, variable flows,
conductivity, temperature, and fish size
can alter the effectiveness and induce
injury under some operating conditions.

Strobe lights and underwater sound
transducers also have been used to repel
fish, but additional studies are needed to
determine their effectiveness for adult
upstream migrants.

Modified project operation can
influence fish injury and migration delay.
Depending on site hydraulics, greater or
lesser amounts of water in a bypassed
reach of river may allow more suitable
passage conditions.

Cycling operation or partial loading
of a turbine may allow fish to enter the
draft tube and contact rotating equipment.
Preferential operation of units, or shut
down of problematic units may reduce
some fish injuries. At large powerhouses
with multiple units, selectively operating

Page 32

Impacts of Hydroelectric Plant Tailraces on Fish Passage


Annotated Bibliography

Vogel, C. A., K. R. Marine, and J. G. Smith. 1990. A summary of evaluations of upstream
and downstream anadromous salmonid passage at Red Bluff Diversion Dam on the
Sacramento River, California, U.S.A. In: Proceedings of the International Symposium on
Fishways 1990 in Gifu, Japan. October 8-10, 1990.

Additional Literature:

Brown, R. L. 1991. Bioengineering problems in river systems of the Central Valley,
California. American Fisheries Society Symposium 10:19-31.

PACIFIC SALMON
MIGRATION DELAY
FLOW MODIFICATIONS
= FISH LADDER DESIGN

LOCATION OF STUDY:

Red Bluff Diversion Dam, Sacramento River (river mile 243), California.

PROJECT CHARACTERISTICS:

The Red Bluff Dam has diverted water for irrigation purposes since 1966. Minimum river
flow at Red Bluff ranges from about 3,000 to 4,000 cfs, and normal flows range from 10,000
to 20,000 cfs depending on the season. The dam has 11 weir-controlled, fixed-wheel
overflow gates (each 60 feet wide) that raise the river level 13 to 15 feet depending on the
time of year. Upstream migrants pass upstream of Red Bluff by ascending one of two fish
ladders that are located at either end of the dam. The entrance flow capacity of each fish
ladder is 88 cfs with additional attraction flows of about 250 cfs.

BI ICAL CHARACTE
Chinook salmon and steelhead trout migrate to spawning grounds upstream of the Red Bluff
Diversion Dam each year. There are several seasonal runs (e.g., winter run; summer run)

of chinook salmon that result in adult salmon migrating upstream during all 12 months of
the year.

EFFE IN TRE,

Because the Red Bluff is a diversion dam, not a hydroelectric project, there is no injury or
mortality associated with draft tubes or turbine blades. Studies conducted in the 1970s and

Page 94 Impacts of Hydroelectric Plant Tailraces on Fish Passage


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