EPA
TVA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/7-80-094
May 1980
Tennessee Valley
Authority
Division of Energy EDT-102
Demonstrations and Technology ,
Chattanooga, TN 37401 O • I
Evaluation of
Two Concepts for
Protection of Fish
Larvae at Cooling
Water Intakes
Interagency
Energy/Environment
R&D Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
the views and policies of the Government, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-80-094
May 1980
Evaluation of Two Concepts
for Protection of Fish Larvae
at Cooling Water Intakes
by
D.A. Tomljanovich, J.H. Heuer, M. Smith,
P. Smith, S. Vigander, and R. Whittaker
TVA
Office of Natural Resources
Norris, Tennessee 37828
and
J.B. Brellenthin, J.T. Johnson,
and S.H. Magliente
TVA
Division of Energy Demonstrations and Technology
Chattanooga, Tennessee 37401
EPA Interagency Agreement No. IAG-D8-0721-BE
Program Element No. INE624A
EPA Project Officer: Theodore G. Brna
TVA Project'Director: Hollis B. Flora, II.
Industrial Environmental Research Laboratory
Office of Environmental Engineering and Technology
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
U.S. Environmental Protection Agency
Region V, Library
230 South Dearborn Street
Chicago, Illinois 60C-4
-------
DISCLAIMER
This report was prepared by the Tennessee Valley Authority and has been
reviewed by the Office of Energy, Minerals, and Industry, U.S. Environmental
Protection Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of the Tennessee
Valley Authority or the United States Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
111
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ABSTRACT
Laboratory studies were conducted to evaluate two screening concepts for
protecting larval fish at water intakes. Initial experiments with the "impinge-
release" concept were designed to evaluate several variables affecting percentage
retention and survival of larvae impinged for short periods of time on small-
opening continuous traveling screens. These Variables included species, screen
opening size, approach water velocity, and impingement duration.
Subsequent experiments with this concept were designed to evaluate several
fish handling components of a proposed vertical traveling fine-mesh screen,
the purpose of which was to identify and modify, as necessary, any components
of the screen or operating scheme that likely would result in high fish mortality.
These components included impingement duration, exposure of the larvae to a
"dry" screen as the screen panel traveled from the surface of the water to the
top or spilling position, spilling of the larvae into a fish return trough,
approach water velocity, sprays, and screen panel shape. Seventeen species of
larvae representing a wide range in hardiness were used to evaluate this concept.
Investigations on a second concept ("fish avoidance") were designed to
evaluate the ability of larval fish to avoid being entrained through and impinged
against a stationary intake screen featuring low inlet velocities and narrow
slotted openings. Experimental variables included velocity through the slot,
screen slot orientation (perpendicular vs parallel) to flow, illumination condi-
tion (day vs night), screen slot width, a bottom refuge, fish age, and screen
length. Twelve species of larval fish were used to evaluate this concept in a
flowing water environment.
This report was submitted in fulfillment of Task 3 Subagreement 21 of the
interagency agreement between TVA and EPA (TV-41967A, EPA-IAG-D8-0721BE) under
the sponsorship of the U.S. Environmental Protection Agency. This report covers
the period January 1, 1977, to February 7, 1980, with work completed as of May 7,
1980.
IV
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TABLE OF CONTENTS
Abstract iv
Figures vii
Tables viii
Acknowledgements xi
I. Introduction . 1
2. Conclusions and Recommendations 7
3. Impinge-Release Concept 10
Materials and Methods 10
Results and Discussion 17
4. Fish Avoidance Concept 39
Materials and Methods 39
Results and Discussion ..... 44
References 59
Glossary 60
Appendices
A. Impinge-Release Concept - Summary of Initial
Feasibility Study 61
B. Fish Avoidance Concept - Summary of Initial
Test Year . 71
C. Formula for Adjusting Test Results to
Include 24-hour Control Mortality 94
D. Analysis of Variance for Four Species Subjected
to Impingement, Air Exposure, and Spilling 96
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FIGURES
Figures Page
1 Three applications of the "impinge-release" method of
fish protection using continuous traveling screens 2
2 Horizontal traveling screen, schematic drawing 3
3 Laboratory test facility used to evaluate the effect of several
fish handling components of a continuously traveling fine-mesh
screen on larval fish survival 11
4 Two screen panels that were used to evaluate the survival of
larval fish exposed to several fish handling components of a
prototype fine-mesh traveling screen 12
5 Effect of approach water velocity and impingement duration on
survival of fish larvae subjected to impingement and spilling
into return trough on a laboratory model fine mesh screen .... 30
6 TVA Engineering Laboratory test flume for the study of fish
behavior near stationary screens 40
7 Stainless steel wedge wire screens used in the laboratory test
flume to evaluate the "fish avoidance" concept of protecting
fish larvae at water intakes 41
8 Average water velocity in the "fish avoidance" flume from
upstream end of test section #1 to downstream end of test
section #5 for two slot velocities 56
9 Effect of screen length on entrapment avoidance by
larval fish 58
VI
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TABLES
Table
1 Average sizes and ages of fish larvae used to evaluate
a laboratory model fine-mesh traveling screen 18
2 Results of analyses of selected water quality parameters
for water used in tests of a laboratory model fine-mesh
traveling screen 20
3 Initial and 24-hour survival of control fish used in
laboratory tests in 1978 and 1979 on a fine-mesh
traveling screen 21
4 Results of seven species which showed high 24-hour survival
to all test conditions designed to evaluate several fish
handling components of a laboratory model vertical traveling
fine-mesh screen 23
5 Summary results of two species of larval fish which showed the
lowest survival response to test conditions on a laboratory
model fine-mesh traveling screen 24
6 Summary results of four species of larval fish which showed
moderate to high survival response to test conditions on a
laboratory model fine-mesh traveling screen 26
7 Summary of analysis of variance results of impingement,
air exposure, and spilling 28
8 Summary of analysis of variance (ANOVA) results comparing
"impingement plus spill from the wet screen" with "impingement
only" nested over impingement durations 28
9 Average percentage of fish that remained in the tray after
passing through the spill position and spray 34
10 Comparison of percentage adherence of striped bass larvae
between screen angles and between screen travel speeds 35
11 Effect of panel shape on survival of fish larvae tested on
a laboratory model fine-mesh traveling screen 36
12 Experimental variables tested in the "fish avoidance"
concept flume studies 43
VII
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TABLES
(Continued)
Table
13 Age and mean size of fish tested in the "fish avoidance"
laboratory flume 46
14 Summary of all "fish avoidance" tests that were conducted
in the second test year , . 47
15 A summary of the experimental designs used to investigate
"fish avoidance" during the second test year 48
16 Results of Duncan's multiple range tests for significant
main effects of ANOVA analyses for slot velocity and slot
orientation 49
17 Mean avoidance for the combined levels of slot velocity and
slot orientation for two species which showed significant
interaction in a two-way ANOVA design 49
18 Results of Duncan's multiple range tests for significant
main effects of ANOVA analyses for slot velocity, slot
orientation, and diel period 50
19 Mean avoidance for combined levels of slot velocity and slot
orientation and diel period and slot orientation for species
which showed significant interactions in a three-way ANOVA
design 50
20 Results of Duncan's multiple range tests for significant main
effects of ANOVA analyses for slot velocity and diel period ... 51
21 Results of Duncan's multiple range tests examining significant
main effects of ANOVA analyses for slot velocity, diel period,
and slot width as independent variables 52
*
22 Mean avoidance of white sucker for the combined levels
of slot width and diel period and slot width and slot
velocity; the significant interaction effects in a
three-way ANOVA design 52
23 Results of Duncan's multiple range tests for significant main
effects of ANOVA analyses for slot velocity and slot width. ... 53
24 Mean avoidance for the combined levels of slot width and
slot velocity for three species which showed significant
interaction in a two-way ANOVA design 53
Vlll
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TABLES
(Continued)
Table
25
26
27
28
Results of Duncan's multiple range tests for significant main
effects of ANOVA analyses for slot velocity and bottom
refuge
Results of Duncan's multiple range tests for significant main
effects of ANOVA analyses for slot velocity and fish age. . .
Mean avoidance for the combined levels of fish age and
slot velocity for two species which showed significant
interaction in a two-way ANOVA design
. 54
. 54
Comparison of mean avoidance between dead and live
larvae of two species at each slot velocity . . . .
55
5?
IX
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ACKNOWLEDGEMENTS
Appreciation is extended to the following agencies for supplying larval fish:
Department of Conservation of Natural Resources
Alabama Game and Fish Commission
Department of Natural Resources
Georgia Game and Fish Commission
Minnesota Department of Natural Resources
Tennessee Wildlife Resources Agency
Texas Instruments
U.S. Fish and Wildlife Service
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SECTION 1
INTRODUCTION
In recent years increased attention has been directed at fish protection in
the design and location of power plant intake structures especially since the
enactment of Public Law 92-500 and the 1972 amendments which, under section 3l6(b),
provide for "best technology available for minimizing adverse environmental impact."
An important consideration in the evaluation of cooling water intake screen
systems as a mitigative device is the smallest fish that these devices and designs
are capable of protecting.
Conventional traveling screen designs have effectively divided the fish com-
munity into two sizes: those that are retained by a standard 9.5 mm (3/8") mesh
screen (impinged) and those that pass through the 9.5 mm screen (entrained). In
the past, efforts were focused on ways to reduce impingement at existing plants
while entrainment was largely neglected. TVA and EPA, as well as other organiza-
tions, have directed research efforts toward reducing impingement and entrainment
mortality through improved screening technology.
A review of available literature identified two screening concepts with poten-
tial for reducing entrainment and impingement. This report details laboratory
investigations on these concepts, the impinge-release concept and the fish
avoidance concept.
Impinge Release Concept
In this concept, larval fish are retained in front of the intake structure
by one or more continuously traveling fine-mesh screens. After impingement on
the screen for a short time, the fish are released into a bypass or return trough
and returned to the source water body.
Figure 1 illustrates three types of impinge-release systems that are currently
available or are being considered for application to vertical travelling screens.
The difference in fish handling among these screens is primarily in the method of
transferring the fish from the screen panel to the fish return trough. In the
single-entry, double-exit screen, fish are poured out of the panel directly into
the return trough as the screen panel moves around the upper sprocket. In the
other two screen types, the fish are either flushed out of the panel by a high
volume flood of water or are spilled into a trough as the panel moves toward the
back side of the sprocket. An additional impinge-release system, the horizontal
traveling screen (Figure 2), rotates the screens horizontally beneath the water's
surface releasing impinged material at the downstream end, eliminating air
exposure of impinged organisms and screen panels.
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CENTER FLOW
THROUGH FLOW
THROUGH FLOW
DRIVE
SPROCKET
SPRAY
SLIDE
RETURN
TROUGH
SEMI-CIRCULAR
SCREEN
PANELS
r~
/-
SPRAY
SCREEN
ROTATION
DRIVE
SPROCKET
FISH
BUCKET
FLAT
.SCREEN
PANEL
RETURN
TROUGH
SPRAY
TILTED
SCREEN
PANEL
WATER
SURFACE /—
FLOW
SEAL
SEAL
Figure 1. Three applications of the "impInge-release" method of fish protection using continuous traveling screens.
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TRASH BARS
STREAM
SPRAY HEADER
FOR TRASH REMOVAL
CONTINUOUS
ROTATION
f-
CIRCULATING WATER PUMPS
Figure 2. Horizontal traveling screen; schematic drawing.
Source: Document for Best Technology Available for the
Location, Design, Construction and Capacity of
of Cooling Water Intake Structures for Minimizing
Adverse Environmental Impact. EPA 440/1-76/015-a,
Washington, DC, April 1976.
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Sazaki et al., (1972) conducted laboratory tests on the retention and impinge-
ment tolerance of larval and juvenile chinook salmon (Oncorhynchus tshawytscha),
steelhead trout (Salmo gairdneri), striped bass (Morone saxatilis), and striped
bass eggs. The purpose of the tests was to determine "if impingement is a feasi-
ble concept in screening" to protect the anadromous fishery resources at the 623
m3/s (22,000 cfs) Peripheral Canal water diversion in California. They found that
a screen with openings no greater than 0.4 mm was needed to retain all striped
bass larvae, the smallest fish tested. Although survival of striped bass eggs
and larvae was high under several test conditions, it was concluded that screen-
ing was not feasible for individual striped bass larvae less than 40 mm (1.6 in.)
in length at velocities exceeding 18.3 cm/s (0.6 fps).
In another study, Prentice and Ossiander (1971) obtained essentially 100
percent retention and survival of 26 mm (1 in.) chinook salmon (Oncorhynchus
tshawytscha) on a screen with 2.5 mm openings at approach velocities up to 30.5
cm/s (1 fps) and impingement durations up to 30 minutes.
In TVA's initial feasibility study conducted in 1976, (Appendix A), several
variables which could influence the success of the impinge-release concept were
identified. These variables included the size of screen opening, the water
velocity in front of the screen (approach velocity), and the length of time that
the fish were retained on the screens (impingement duration). The hypothesis was
that retention on a fine-mesh screen would depend primarily on some body dimen-
sional feature of the fish and secondarily on approach velocity and/or impingement
duration. A second hypothesis was that survival of these retained larval fish
would be primarily dependent on impingement duration and secondarily dependent on
approach velocity and fish size. Finally, large interspecies differences were
expected, especially in survival of the retained individuals. The results of
these initial studies indicated:
1. It is feasible to retain larval fish with fine-mesh screens.
2. The most important experimental variable with respect to percent
retention is mesh size.
3. A 0.5 mm screen opening retained 98 percent of the smallest larval fish
tested.
4. Impingement durations up to four minutes resulted in 80-100 percent
survival.
5. Low current velocities £30.5 cm/s (1.0 fps) through the screen provided
the highest survival.
Based on these results, a second phase of the study was conducted during
1977-1979. The purpose of the second phase was to evaluate larval fish survival
associated with all aspects of fish handling on a laboratory screen. These data
will be used to optimize survival of fish by modifying any components of the screen
which cause significant mortality to the larvae. This report describes the labora-
tory model test screen, experimental designs, results of tests, and identifies
remaining areas of study that need to be addressed in order to develop a final
prototype design.
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Fish Avoidance Concept
This concept depends on the ability of the fish to swim away from the intake.
Basic fish protection requirements of this concept, which enable larvae to swim
away from the screen, include small openings and low water velocities through the
screen. This concept is being evaluated for application to a stationary screen.
Larval fish just a few days old are capable of orienting to low water veloci-
ties (Tomljanovich et al., 1977). Sazaki et al. (unpublished report, California)
tested swimming abilities of larval and juvenile Chinook salmon, steelhead trout,
and striped bass. They found that 90 percent of the 10-12 mm striped bass tested
were able to maintain themselves in a current of 6.1 cm/s (0.2 fps) for six minutes
while 90 percent of the 50 mm fish were able to maintain themselves in an 18.3
cm/s (0.6 fps) current for six minutes.
Sevefal applications of the fish avoidance concept have been suggested for
possible use at low-volume power plant intakes. Stober et al. (1974) conducted
studies on the use of rapid sand filters for protecting larval and juvenile fish
and large invertebrates from entrainment into power plant intakes. McSwain and
Schmidt (1976) reported on the use of a gabion screen in combination with perfo-
rated pipes buried in river-run gravel to protect juvenile salmon in the Merced
River in California. Water passes through the gravel and perforated pipes at
velocities low enough to prevent fish entrapment. Richards and Hroncich (1976)
reported the development of a perforated pipe intake for the protection of fish
at a 1.58 m3/s (55.7 cfs) water pumping station on the Columbia River. In this
design, the pipes rested on supports above the river bed rather than in the sub-
strate. The perforations were 9.5 mm in diameter and the velocity through them
was 15.2 cm/s (0.5 fps). The approach velocity 9.5 mm from the screen was reduced
to 6 cm/s (0.2 fps).
The design of a fish avoidance screen is necessarily dictated by the swimming
ability and behavior of the species of larval fish that are to be protected, the
site specific physical characteristics of the intake location, and requirements
for plant water flow. If an intake based on this concept is successful in protec-
ting larval fish, it will also provide protection for juvenile and adult fish which
have greater swimming ability.
The fish avoidance study was designed to estimate the ability of several
species of larval fish to avoid impingement against and entrainment through a
fish avoidance screen in flowing water. This concept also may have potential for
use in nonflowing situations. The stationary test screen used was made of slotted
stainless steel with wedge-shape wire (Smith 1977).
The safe transport of larval fish past such an intake was expected to be
influenced by the following variables:
1. Screen dimensions and shape.
2. Width of screen slot opening.
3. Combination of slot (through-screen) and bypass water velocities.
4. Proportion of total flow withdrawn through the intake screen.
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5. Orientation of the screen with respect to the river flow.
6. Differences in behavior, size, and swimming ability among different
larval fish species.
As in the impinge-release concept, the fish avoidance project was conducted in
two phases, an initial feasibility study (Appendix B) and a phase two effort.
The basic analysis of the first phase of the study compared proportion of
total number of fish bypassed (avoidance) with proportion of total flow bypassed.
The hypothesis tested was that the larvae were essentially passive with respect
to swimming ability and if homogeneously distributed in the approach flow, they
would be entrained and bypassed in the same proportions as the respective bypassed
and entrained portions of the flow. In these tests fish were exposed to a 1.2-m-
long section of screen. The above hypothesis was rejected; all species except
very young muskellunge had higher proportion bypass values than corresponding flow
bypass values under most experimental conditions. These results suggested that a
large proportion of larval fish and probably all juvenile-adult fish that would
be exposed to this type screen could avoid entrapment.
In the second phase additional laboratory tests were conducted in 1978 to
more fully evaluate the "fish avoidance" concept. The primary objective was to
evaluate the effect of several experimental variables on avoidance of entrapment,
including illumination, slot orientation, through-screen velocity, slot width,
fish age, a bottom refuge, and screen length.
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SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
Impinge-Release Concept
The objective of this study was to provide the necessary information to
evaluate fish handling components of a prototype fine-mesh intake screen using
the impinge-release concept. The initial results showed that the amount of modi-
fication needed to optimize survival will depend largely on the species and life
stages to be protected.
A large range in survival among species suggested that a similar pattern would
be found in the natural environment using a prototype screen. Consequently, an
average survival rate for larval fish would not be meaningful. Much of the range
in survival among species was related to size differences for a given age among
species.
If a species that has relatively large larvae is to be protected, little or
no modification to the basic fine-mesh screen may be needed. For this group of
larvae, 90 to 100 percent 24-hour survival after four minutes "impingement plus
spilling into a return trough" can be expected. However, for protection of small,
fragile larvae, such as striped bass, considerable modification may be required
to provide optimum protection. To date, tests discussed here have shown only
limited success in protecting the very fragile species using the impinge-release
screening concept. However, high control mortality in tests with these species
suggested that the laboratory studies have not adequately described the effect of
the screen on survival.
In the impinge-release tests, impingement had the greatest effect on survival,
followed by exposure to air as the larvae traveled in a "dry" screen to the spill-
ing position. Survival of larvae after spilling into the return trough was not
consistent between two types of tests. Additional studies need to be conducted
on this aspects of the impinge-release system.
For species of intermediate hardiness, (redbreast sunfish, largemouth bass,
bigmouth buffalo, walleye) it appeared that providing a water trough to the
screen panel, limiting the impingement time to four minutes or less, and provid-
ing low pressure sprays for fish removal would significantly increase survival.
For five species tested (smallmouth and largemouth bass, river carpsucker,
black buffalo, walleye) approach water velocities of 30.5 cm/s (1.0 fps) or
less did not significantly affect survival. Velocities equal to or greater
than 61 cm/s (2.0 fps), especially when impingement duration exceed two minutes,
can be expected to reduce survival for most species of similar hardiness to those
tested. Most larvae adhered to the screen panel fabric when the panel was raised
-------
from the water. An emergent spray installed near the water surface rinsed the
larvae into the water-holding tray at the bottom of each screen panel. A low pres-
sure spray of sufficient volume to gently rinse the fabric consistently transferred
both larvae and weeds into the tray. It was apparent from observation that neither
this spray nor the overhead low volume spray, used to ensure that all larvae spill
into the fish return trough, would be an important source of mortality.
Small larvae of some species which have distinct filiform shaped bodies will
become entrapped in screen openings of 0.5 mm square mesh. A low pressure emergent
spray would be ineffective in rinsing them out of the fabric. Additional testing
with smaller opening screens is needed to determine the maximum screen opening
that could be used to prevent entrapment for these fish.
Comparisons of screen panel shapes suggested that higher survival will be
obtained if the larvae are impinged against the fabric (rather than being allowed
to reside in an eddy produced by a high tray lip). Only a few centimeters of water
depth are required for larvae and juvenile fish to reside in during screen travel.
Self-cleaning angled screens were not found to consistently rinse the larvae
into the tray upon screen panel emergence and sometimes resulted in lower survival
than conventional screens. However, these screens were not tested extensively
and a more indepth evaluation of unique screen panel shapes may be warranted.
To adequately describe the effect of the impinge-release process on the
larvae, it may be necessary to more fully evaluate the shock response observed
for several species. It would appear that a recovery time exceeding several
minutes would impair the ultimate survival of stunned fish discharged back to the
source water body. An intermediate holding facility may need to be considered in
some cases to allow the fish to recover prior to returning them to the source water
body.
Fish Avoidance Concept
The results of this study indicated that a "fish avoidance" water intake
screen has high potential for protecting a large percentage of fish larvae which
could potentially be entrapped. All variables that were tested represent import-
ant design parameters for a prototype screen. In addition, large differences in
avoidance among species and ages dictate the need to consider species and sizes
of fish available at a particular site when designing an intake of this type.
The tests indicated that to provide optimum protection for very small larvae
(<6.0 mm total length) a screen slot width of 0.5 mm and a slot velocity no greater
than 7.5 cm/s may be required.
Use of a 1.0 mm slot and sufficiently low through-screen velocity would prob-
ably enable all larvae over 10 mm total length to avoid entrapment. For some
species a through-screen velocity as high as 15.0 cm/s would not appreciably reduce
avoidance, but for others it would be necessary to limit slot velocity to 7.5 cm/s
(0.25 fps). Several species between 7 to 10 mm total length would probably avoid
a screen of 1.0 mm slot width if through-screen velocity was limited to 7.5 cm/s.
For some species slot orientation and lighting may need to be considered in order
to optimize avoidance.
-------
A screen with 2.0 mm wide slots could be used to effectively protect most
species of larvae which exceed 10 mm length. With this slot size, use of low slot
velocity (7.5 cm/s) and orienting the slots perpendicular to flow direction may
be required to optimize avoidance for most species. Higher slot velocity could
be used and still provide adequate protection for juvenile and larger fish during
periods when larvae are not present.
Inclusion of a bypass area located below the screen (in the case of a vertical
flat screen oriented parallel to flow direction) probably would increase avoidance
for nearly all species.
A prototype screen should also be designed to provide sufficient velocity at
the downstream end of the intake to prevent reversal of stream flow. This pro-
vision will preclude problems associated with reexposure of the larvae to the
screen by ensuring that once bypassed they will be carried downstream away from
the intake.
Because of the potentially significant effect of so many design parameters,
it is obvious that a generalized optimum screen cannot be proposed. The results
of this study will be useful for site specific designs after an indepth evaluation
has been made of the fish species present and other biological and nonbiological
considerations have been assessed.
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SECTION 3
IMPINGE-RELEASE CONCEPT
MATERIALS AND METHODS
Summary of Initial Laboratory Study
A complete discussion of the test facility, test procedures, experimental
variables, results, and conclusions is presented in Appendix A.
Results of the first year of study suggested that most species of larvae could
be retained on a screen having 0.5 mm openings and that sufficiently high survival
could be obtained for many species if impingement duration was limited to four
minutes or less. There was no basis on which to estimate the effect on survival
of the remaining stresses associated with the impinge-release process. Thus, a
second phase of laboratory testing was begun in spring 1977, the purpose of which
was to evaluate all of the fish handling components of a single-entry, double-
exit vertical travelling screen.
This phase of the study was conducted over a period of three years during
the several months when larval fish were available. During the first year of
this phase it became apparent that abnormally high ambient water temperatures of
the laboratory water may have adversely affected survival. During the second year
of this phase, a chilling unit was installed which enabled matching the flume
temperature to holding water temperature.
Test Facility
In early 1977, construction was started on the laboratory test screen. Since
the test facility was not completed until well into the larval fish season, only
four species were tested in 1977. Provisions were made for installing a refrigera-
tion unit capable of regulating flume water temperatures. Installation of this
unit was completed midway into the 1978 testing program.
The test screen was installed in a 15.2 m long by 1.2 to 2.4 m wide by 1.2 m
deep flume (Figure 3). Although the test facility did not resemble the prototype
in appearance, each prototype fish handling component to which the fish would be
exposed was represented. A rail hoist rather than a sprocket similar to that
found in the prototype was used to mount two screen panels, each 53 cm high and
1.2 m wide. The rail hoist provided greater working space for the experimenters
without altering the actual trajectory of screen travel. During the first two
years of Phase II testing the top panel was flat and the bottom panel was semi-
circular (Figure 4). Each screen panel was divided in half by a vertical baffle.
On the right half of each panel, the bottom few centimeters of screen fabric were
sealed with epoxy paint (Figure 4). This created the "wet" screens: as the screen
10
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SCREEN
DRIVE
DRIVE SPROCKET
POSITION IN
THE PROTOTYPE
FLOW
METER
FLOW
CONTROL
VALVE
-U
\FISH RETURN
SLIDE
SPRAY HEADER
SCREEN PANELS
IN SPILLING POSITION
VERTICAL TRAVELING
SCREEN TRACK
FLOW
STRAIGHTENER
WATER
SURFACE ~
FISH INJECTION
FUNNEL
WATER
FLOW
-1 />-SCREEN PANEL
f IN IMPINGING
\ POSITION
J
DEPTH
CONTROL
GATE
RETURN FLOW
ELEVATION
Figure 3. Laboratory test facility used to evaluate the effect of several fish handling components of a continuously
traveling fine mesh screen on larval fish survival.
-------
CENTRAL
DIVIDING
BAFFLE
SCREEN
0.5 mm
OPENING
DEBRIS LIP
WET
POOL
FISH
BUCKET
Figure 4. Two screen panels that were used to evaluate the survival of
larval fish exposed to several fish handling components of a
prototype fine mesh traveling screen.
12
-------
panels were raised out of the flume, a shallow pool of water was retained in the
"wet" portion of each panel. The unsealed left side of each panel ("dry" screen)
did not hold a pool of water. The screen dimensions (except width), overhead
sprocket diameter (in this case rail curvature), and the length of the fish slide,
which extended from the spill position to the fish return trough, were prototype
size. During the third year of testing, additional panel shapes were tested.
During Phase II testing, several separate experiments were conducted. During
the first two years, tests were limited to the first experiment which are labeled
the baseline tests. During the third year, three additional species were tested
under these same conditions, and several other experiments were conducted.
Description of Experiments
1. Evaluation of Effect of Impingement Duration, Air Exposure During Screen
Panel Emergence and Travel to Spilling Position, and Spilling into Return
Trough. This baseline experiment evaluated survival among levels of expo-
sure to these three major fish handling components of the impinge-release
process.
A complete test series of each impingement duration and species included:
(1) impingement alone, (2) impingement plus spilling into return trough without
air exposure (fish were carried to spill position in the "wet" screen), (3) impinge-
ment plus one minute air exposure, (4) impingement plus one minute air exposure
plus spilling into return trough, (5) impingement plus three minutes air exposure,
and (6) impingement plus three minutes air exposure plus spilling into return trough.
"Impingement alone" represented the lowest level of exposure to the test facility
whereas "impingement plus spilling from the wet screen into the fish return trough"
(no air exposure) represented the lowest level of exposure that can be designed
for a prototype vertical traveling screen (excluding sprays and the ride back to
the river via the fish return trough). The remaining categories of testing repre-
sent kinds of exposure the fish would experience on an unmodified screen panel.
It was hypothesized that as the exposure increased, survival would decrease.
Experimental Variables
Screen panel shape
Screen opening
Approach water velocity
Screen travel speed
Impingement duration
Air exposure duration
Fish species
flat semicylindrical
0.5 mm
15.0-22.9 cm/s (0.5-.75
6.4 m/min (21 fpm)
1.0, 2.0, 4.0 min
1.0, 3.0 min
Paddlefish
Northern pike
River carpsucker
Quillback
White sucker
Channel catfish
Smallmouth buffalo
Bigmouth buffalo
Black buffalo
Striped bass
Striped bass
x white bass
fps)
(Polyodon spathula)
(Esox lucius)
(Carpiodes carpio)
(C. cyprinus)
(Catostomus commersoni)
(Ictalurus punctatus)
(Ictiobus bubalus)
(I. cyprinellus)
(Ictiobus niger)
(Morone saxatilis)
(Morone hybrid)
13
-------
Redbreast sunfish (Lepomis auritus)
Largemouth bass (Micropterus salmoides)
Walleye (Stizostedion vitreum)
A three-replicate design was employed for all tests. In each test a sample
of fish was removed from the transfer container and placed in a beaker. These
test fish were carefully examined and any dead fish removed before testing. The
live fish were introduced into the current directly in front of the test screen
via an L-shaped 25 mm diameter plastic pipe (Figure 3). In the "impingement only"
tests, after one, two, or four minutes impingement, the test screen panel was
raised, leaving only the bottom few centimeters on the panel immersed. As the
upper portion of the screen panel emerged from the water, any impinged fish which
adhered to the screen were gently splashed into the water at the bottom of the
panel. These fish were then siphoned into a styrofoam cooler. Dead individuals
were removed and counted, and the live fish were left in the cooler for 24 hours
to assess delayed mortality. This part of the test series (impingement only) pro-
vided a means for determining the effect of additional fish handling components.
In the "impingement plus air exposure" tests, the screen was raised com-
pletely out of the water following the impingement period, and the impinged fish
were exposed to the air for one or three minutes to simulate travel time of an
unmodified prototype screen panel from the water surface to the top of the screen
structure. At screen speeds of 4.2 and 8.5 m/min (14 and 28 fpm), a three-minute
air exposure represents a range of total distance from water surface to the top
of the screen structure of 12.6 to 25.5 m (41 to 84 ft). Immediately following
the air exposure period, the bottom portion of the screen panel was lowered into
the flume to facilitate siphoning the fish into coolers. Dead fish were immedi-
ately removed and counted, and live fish were held 24 hours for assessment of
delayed mortality.
The next test of the series consisted of impingement, followed by exposure
to air (one or three minutes), followed by spilling a distance of approximately
1 m into a return trough. As the screen panel reached the spill position, a gen-
tle spray directed from behind the screen was used to flush all fish from the panel,
The fish were siphoned from the trough into a styrofoam container and treated as
described for earlier tests.
In the final test of the series, the fish were impinged, carried to the spill
position in the pool of water in the "wet" screen, spilled into the return trough,
and removed and treated as described for the other tests.
2. Evaluation of Effect of Approach Water Velocity on/mortality of larvae which
were exposed to impingement and spraying followed/by spilling into the fish
return trough. All species were tested using the flat vertical screen.
Tests with largemouth bass also included a curved panel.
The velocities and impingement durations tested for each species are listed
below:
14
-------
Approach Water Impingement
Species Velocity in cm/s Duration in min.
Black buffalo 15.0 (.5 fps), 30.5 (1 fps) 1, 2, 4
Walleye 15.0 (.5 fps), 30.5 (1 fps) 1, 2, 4
River carpsucker 15.0 (.5 fps), 30.5 (1 fps),
61 (2 fps) 2, 4, 8
Largemouth bass 23.0 (.75 fps), 46 (1.5 fps) 4, 8
Smallmouth bass 30.5 (1 fps), 61 (2 fps) 4, 8
3. Evaluation of Sprays. Several aspects of spraying were evaluated:
a. Effectiveness in transferring fish from position of adherence on screen
mesh to water in screen panel tray.
b. Effectiveness in transferring fish from screen panel tray to return
trough.
c. Effect on survival of larvae impinged and spilled into a return trough.
The test facility was designed to simulate the collection and removal
process of a single-entry, double-exit vertical traveling screen. With
this type screen the debris, water, and fish spill over the tray lip
rather than over the screen itself as in the case of conventional
through-screens (Figure 1). Therefore the fish are spilled directly
into the fish return system without being exposed to the air or screen
surface. The screen panel tray begins to spill when it starts to travel
around the top sprocket. Length of time required for the panel to com-
pletely spill is dependent on the design of the tray, diameter of the
sprocket and speed of screen travel. Most screen panel contents empty
before reaching the sprocket axle. This is recommended to minimize
stress to the fish during the process of returning them to the source
water body via the return system.
Two rows of spray nozzles were installed to enhance the safe transport of
larvae through the screening process (Figure 3). To facilitate rinsing any
impinged fish into the water holding portion of the screen panel, one row of
spray nozzles was mounted behind the screen on a 5 cm diameter steel pipe mani-
fold located approximately 40 cm above the water surface. This emergent spray
consisted of six deflector type flat spray nozzles mounted on 14 cm centers.
This spray could be moved from 5 to 30 cm from the screen panel and could be
rotated to change the angle at which the spray hit the screen. Flow rate
through this spray ranged from approximately 0.9 to 1.3 iL/s (14 to 20 gpm) .
A second row of sprays was installed to assist in removing fish and debris
from the screen panel in the spill position. This low pressure spray initially
consisted of six full cone center jet nozzles mounted on a 7.6 cm (3 in.) diameter
PVC pipe manifold. Later, five additional nozzles were installed to achieve closer
spacing and more complete coverage of the screen panel. These 11 nozzles were
mounted on 7.6 cm centers and were positioned approximately 40 cm above the screen
panel roller guide. Total flow rates ranged from approximately 1.0 to 2.3 H/s
(15.5 to 36.5 gpm).
Evaluation of the requirements and effects of the overhead spray for assist-
ing in spilling fish into the return trough was mostly based on observations and
15
-------
trial and error adjustments of the spray angle, pressure and distance from the
screen panel. The number of fish remaining in the panel tray was recorded for
four species during tests in which 11 nozzles were installed.
Variables included in tests for survival were spray volume, spray angle to
screen, cleanness of screen (clean vs clogged), approach water velocity, screen
panel shape, impingement duration, and screen travel speed. Species tested
included black buffalo, striped bass, walleye, striped x white bass, quillback,
river carpsucker, largemouth bass, smallmouth bass, and bluegill.
4. Evaluation of Screen Panel Design. Several screen panels were tested to
determine the effect of panel shape on (1) adherence of fish to screen
during emergence, (2) spilling, and (3) mortality of the larvae.
Screen panel shapes included flat vertical (Figure 4), flat inclined 30° from
vertical, flat inclined 60° from vertical, curved with standard lip (Figure 4),
curved with high lip, and curved with low lip. All panels were equipped with water
holding trays. Results presented are based on tests using clean screens.
Inclined flat screens were tested primarily to determine if the fish would
avoid adhering to the screen as they emerged from the water. If this were the
case there would be no need for an emergent spray. The possibility also existed
that the larvae could avoid impingement by moving down the angled screen and
getting into the screen panel tray.
The purpose of testing high and low lip curved screens was to compare the
effect on survival of an eddy produced behind both high and standard lip screens
with no eddy in the low lip screen panel. It was noted in previous testing with
the standard lip curved screen that some species were able to avoid impingement
by staying in the eddy produced between the lip and the screen. Species tested
included river carpsucker, striped x white bass, striped bass, black buffalo,
bigmouth buffalo, smallmouth bass, largemouth bass, and walleye.
Acquisition and Pretest Holding of Test Fish
Most species of test fish were obtained as larvae from State or Federal fish
hatcheries. A few species were cultured in-house. Details of culture methods
and success are found in Yeager (1979).
Just prior to testing, the fish were transferred in an 11.42 plastic pail
from the holding tank to the test facility. Prior to installation of the refrig-
eration unit, test fish were acclimated to the higher flume water temperature by
submerging the holding container in the flume and slowly adding flume water to
the holding container until the temperature difference was within 1 C. After
installation of the refrigeration unit, flume water temperature was adjusted to
within ± 1 C of holding water temperatures prior to testing.
Controls
Several control groups were established during each day of testing. Approxi-
mately 25 to 200 fish (depending on the numbers of fish available and hardiness
of species) were removed from the transfer container and placed in a styrofoam
cooler containing water from the test flume. Survival of these control groups at
the end of 24 hours was used to adjust 24-hour survival of four species of test
fish (adjustment formula presented in Appendix C).
16
-------
Numerical Analysis
In all cases, survival of test groups was calculated as a percentage. To
satisfy the assumption of normality for parametric analyses, these data were trans-
formed by an arcsin function (Sokal and Rolfe 1969). For selected species, 24-hour
survival was adjusted for the observed control survival. The effects of the experi-
mental variables were analyzed using multifactor analysis of variance (ANOVA) tech-
niques available with the Statistical Analysis System (SAS), General Linear models
procedure (Barr et al. 1976). Duncan's Multiple Range tests, which were also
available with the SAS procedures, were used to compare mean survival among levels
of each significant effect.
RESULTS AND DISCUSSION
Sixteen species from seven taxonomic families were used to evaluate the
laboratory model fine-mesh traveling screen during the second phase of testing.
The larvae ranged in age from 2 to 16 days and average total length from 5.0 mm
to 16.0 mm (Table 1). These fish ranged in hardiness from very hardy to very
fragile and probably closely approximate the range in hardiness of fish of these
ages that would be found in the natural environment.
Water Quality
Dissolved oxygen was measured regularly throughout the testing period and
ranged between 80 and 95 percent of saturation. Before the refrigeration unit
was installed, holding water temperatures were always lower than corresponding
flume water temperatures. This temperature difference ranged among six species
from 1 C for striped bass to 8.5 C for largemouth bass. For two fragile species,
striped bass hybrid and walleye, flume water temperature exceeded holding tempera-
ture by 5 to 6 C and 5 to 7 C, respectively, during a three-day test period for
each species. Holding temperatures during this period ranged from 15.0 C to 21.0
C compared to 21.5 to 24.4 C for flume temperatures.
Other selected water quality parameters were measured twice in 1978 and once
during 1979, (Table 2). None of these results suggested that poor water quality
(apart from water temperature) contributed to any of the mortality observed.
Control Survival
Initial and 24-hour control survival was usually high for most species
(Table 3). Average initial survival, which was evaluated for the 1979 tests
only, was at least 92 percent for all species except striped x white bass and
bluegill. Twelve species experienced mean 24-hour survival of at least 95
percent for one or more age groups or test years.
Striped x white bass hybrid tested in 1979 arrived in poor condition (evi-
denced by about 50 percent mortality) which was reflected in the comparatively
lower initial survival experienced for the hybrid (58 percent) than for the
striped bass (92 percent). Bluegill larvae showed 24-hour control survival equal
to or greater than 75 percent. However, this species showed essentially 100 per-
cent initial mortality after being tested under the least stressful conditions.
17
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TABLE 1. AVERAGE SIZES AND AGES OF FISH LARVAE USED TO EVALUATE A LABORATORY MODEL
FINE-MESH TRAVELING SCREEN. AVERAGE TOTAL LENGTHS WERE DETERMINED FROM
MEASUREMENTS OF INDIVIDUALS FROM SELECTED CONTROL AND TEST GROUPS. THE
LOCATION FROM WHICH SOME SPECIES WERE OBTAINED IS INDICATED IN PARENTHESES.
Species
Paddlefish
Northern pike
River carpsucker
Quillback
White sucker
Smallmouth buffalo
Bigmouth buffalo
Bigmouth buffalo
Black buffalo
Channel catfish
Striped bass
(Georgia)
(New York)
(New York)
(Tennessee)
(Tennessee)
Striped x white bass
Striped x white bass
Redbreast sunfish
Bluegill
Test
Year
1978
1978
1979
1979
1978
1979
1978
1979
1979
1977
1978
1979
1978
1978
1979
1978
1979
Age
(days)
3
6
3
4
5
6
4
4
4
8
7
5
4
3
6
16
5
6
6
15
16
17
5
6
19
ca 8
ca 13
ca 16
Mean total
Length (mm)
14.0
13.5
6.6
7.1
7.4
7.4
9.3
13.5
8.3
7.3
7.1
12.2
6.0
6.0
7.0
5.4
5.3
5.0
6.0
6.5
6.5
7.6
7.9
10.8
6.0
5.8
6.6
Range (mm)
13.0-15.0
13.0-14.5
6.0-7.0
6.0-8.0
7.0-8.0
6.0-8.0
8.5-10.0
12.0-15.0
8.0-8.5
6.5-8.0
6.0-8.0
10.5-14.0
4.5-6.5
6.0-6.0
6.0-8.0
5.0-5.5
5.0-6.0
4.5-6.0
4.0-7.5
5.5-8.0
6.0-7.0
6.0-9.0
6.0-9.0
10.0-12.0
5.0-7.0
4.5-6.5
6.0-7.5
18
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TABLE 1. (continued)
Species
Smallmouth bass
Largemouth bass
Walleye
(Wisconsin)
(Minnesota)
(Wisconsin)
(Minnesota -Duluth)
(Minnesota-St. Paul)
Test
Year
1979
1978
1979
1978
1979
Age
(days)
unknown
5
unknown
4
4
5
6
10
2
3
4
unknown
Mean total
Length (mm)
10.2
7.0
6.0
9.0
9.0
9.5
9.5
10.6
8.0
8.4
9.0
9.2
Range (ram)
9.5-11.0
6.0-7.5
5.5-6.0
8.0-10.0
5.5-10.5
8.0-10.0
8.0-10.0
9.0-14.0
7.0-8.5
8.0-9.0
8.5-9.5
8.0-10.0
19
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TABLE 2. RESULTS OF ANALYSES OF SELECTED WATER QUALITY PARAMETERS FOR WATER
USED IN TESTS OF A LABORATORY MODEL FINE-MESH TRAVELING SCREEN.
Parameter
Temperature (C)
pH
Specific Conductance (umho/cm)
Total organic carbon (mg/2)
BOD (mg/2)
TKN (mg/2)
NH3-N (mg/2)
N02+N03 (mg/2)
Fe (mg/2)
Cu (mg/2)
Cr (mg/2)
5-16-78
23.0
8.0
230
1.3
<1.0
0.19
0.01
0.34
0.16
0.05
<0 . 005
Date
6-28-78
26.0
7.9
230
1.4
<1.0
0.06
0.04
0.38
<0.05
0.07
<0.005
6-19-79
18.7
7.9
200
2.0
1.7
0.08
0.04
0.62
<0.05
0.01
<0.005
20
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TABLE 3. INITIAL AND 24-HOUR SURVIVAL OF CONTROL FISH USED IN LABORATORY
TESTS IN 1978 AND 1979 ON A FINE-MESH TRAVELING SCREEN.
Species
Paddlefish
Northern pike
River carpsucker
Quillback
White sucker
Smallmouth buffalo
Bigmouth buffalo (1978)
Bigmouth buffalo (1979)
Black buffalo
Channel catfish
Striped bass (1978)
Striped bass (1979)
Striped x white bass
(1978)
Striped x white bass
(1979)
Redbreast sunfish
Bluegill
Smallmouth bass
Largemouth bass (1978)
Largemouth bass (1979)
Walleye (1978)
(Wisconsin)
(Minnesota)
Walleye (1979)
(Wisconsin)
(Duluth)
(St. Paul)
Age
(days)
3
6
3-16
4
4
4
8
7
5-12
4
3-16
5-6
6-17
17
5-19
8-16
unknown
5
unknown
4
4-10
2-3
4
unknown
Number of
Replicates
1
3
18
3
1
8
3
3
12
1
10
12
5
2
8
7
3
3
6
10
13
12
8
9
Average
Initial
NT1
NT
100
100
NT
99+
NT
97
99+
NT
NT
92
NT
58
NT
84
100
NT
99+
NT
NT
99+
92
96
Percentage
24-hour
96
98
99+
100
99
99
59
93
99
100
34
46
48
41
99
80
100
86
99+
55
56
99
65
73
Survival
(range)
(55-67)
(0-95)
(29-75)
(0-91)
(23-59)
(71-84)
(71-100)
(17-88)
(14-78)
(45-89)
(63-83)
*Not tested
21
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For a given species, test groups often contained several ages and individuals
from different brood stocks (hatchery location and year class). Large within-
species differences in average survival sometimes resulted between control groups.
For example, mean 24-hour control survival between 8-day-old bigmouth buffalo
tested in 1978 was 59 percent compared to 93 percent for 7-day-old individuals
tested in 1979.
Walleye tested in 1978 were from two brood stocks (Minnesota and Wisconsin)
but showed similar survival (55 and 56 percent). However, walleye tested in 1979
from these locations ranged from 65 to 99 percent, respectively. In this case
the survival of 55 to 65 percent was associated with fish at least 4 days old,
whereas the fish which show 99 percent 24-hour survival were 2 to 3 day-old fish.
Decreased survival may have been associated with a critical life stage change such
as absorption of the yolk sac and change to external feeding.
Evaluation of Effects of Impingement Durations, Air Exposures, and Spilling
Into Return Trough
Thirteen species were used to evaluate the effect of these fish handling com-
ponents. Seven species showed high survival under all test conditions and thus
were not helpful in identifying any components of the screen that might need to
be modified. The results of the 4 minute impingement series with these species
are presented in Table 4. Smallmouth buffalo was also tested at 1 and 2 minutes
impingement and showed 24-hour survival approaching 100 percent under all condi-
tions. Similarly, river carpsucker were tested at 2 minutes impingement as well
as 4 minutes and showed at least 91 percent 24-hour survival under all conditions.
Two species (striped bass and striped x white bass hybrid) showed highly vari-
able and generally poor survival under all test conditions; thus, as above, a sta-
tistical analysis could not be used to identify problem areas in the screening
process. Striped bass showed the lowest survival of the nine species tested.
The first group of striped bass obtained in 1978 experienced nearly 100 percent
mortality during the fourth night after hatching. A limited water quality
analysis did not detect any problems with dissolved oxygen, pH, carbon dioxide,
or temperature. Of 81 tests that were conducted with this species, mean initial
survival was 19 percent, whereas mean 24-hour unadjusted survival was only 2 per-
cent. Table 5 shows the survival results for each test condition. These values
ranged from 6 to 29 percent for initial survival and zero to 7 percent for 24-hour
survival. Survival of control fish (24-hour) for 10 samples averaged 34.3 percent
and ranged from zero to 95 percent. A trend of decreasing survival with increasing
exposure to test conditions was noted only for the two minute impingement series.
In 68 tests with striped bass x white bass hybrid, average initial survival
was 64 percent, and average 24-hour survival was 15 percent. Because of low
24-hour survival for the two-minute impingement series, a complete four-minute
impingement series was not conducted. Table 5 depicts average initial and 24-
hour survival for each test condition. Average initial survival ranged from
21 percent for the highest level of exposure to 86 percent for the lowest level
of exposure. Twenty-four hour survival ranged from zero to 37 percent. Control
survival for five samples averaged 48 percent and ranged from zero to 91 percent.
A relationship of decreasing initial and 24-hour survival with increasing expo-
sure was apparent for both the one and two minute impingement series. Average
initial survival remained above 75 percent where the fish were not subjected to
air exposure. An obvious decline in survival was shown for those test condi-
tions that included exposure to air (Table 5).
22
-------
ro
u>
TABLE 4. RESULTS OF SEVEN SPECIES WHICH SHOWED HIGH 24-HOUR SURVIVAL TO ALL TEST CONDITIONS DESIGNED TO
EVALUATE SEVERAL FISH HANDLING COMPONENTS OF A LABORATORY MODEL VERTICAL TRAVELING FINE-MESH
SCREEN. VALUES DENOTE 24-HOUR UNADJUSTED SURVIVAL FOR THE 4-MINUTE IMPINGEMENT SERIES.
Percentage 24-hour Unadjusted Survival
Northern White Channel River Smallmouth
Test Conditions Paddlefish Pike Sucker Catfish Carpsucker Buffalo Quillback
Impingement only 98 97 100 100 98
Impingement + spill
from wet screen 96 92 100 100 94
Impingement + 1 rain
air exposure - - 99+ 98 95
Impingement + 1 min
air exposure + spill - - 99+ 100 96
Impingement + 3 min
air exposure 92 92 100 99+ 97
Impingement + 3 min
air exposure + spill 95 90 100 98 96
99
99 99
99+
97
99+
97 88
-------
TABLE 5. SUMMARY RESULTS OF TWO SPECIES OF LARVAL FISH WHICH SHOWED THE
LOWEST SURVIVAL RESPONSE TO TEST CONDITIONS ON A LABORATORY MODEL
FINE-MESH TRAVELING SCREEN. PERCENTAGE VALUES REPRESENT ARITHMETIC
MEANS. DASH DENOTES NO OBSERVATION.
Impingement Duration
Average Percentage Initial and Unadjusted
24-hour (in parentheses) Survival
1 Min
2 Min
4 Min
Species
Test Conditions
Impingement only
Impingement + spill
from wet screen
Impingement + 1 min
air exposure
Impingement + 1 min
air exposure
+ spill
Impingement + 3 min
air exposure
Impingement + 3 min
air exposure
+ spill
Striped Bass
29 (2)
10 (1)
16 (0)
7 (0)
18
9 (0)
26 (4)
25 (7)
25 (2)
22 (2)
18 (2)
10 (1)
23 (2)
Striped Bass X White Bass Hybrid
Impingement only
Impingement + spill
from wet screen
Impingement + 1 min
air exposure
Impingement + 1 min
air exposure
+ spill
Impingement + 3 min
air exposure
Impingement + 3 min
air exposure
+ spill
86 (37)
79 (24)
64 (22)
57 (19)
37 (10)
33 (2)
75 (5)
83 (13)
46 (0)
39 (0)
32 (2)
21 (0)
40 (6)
-------
The four remaining species (redbreast sunfish, largemouth bass, bigmouth
buffalo, and walleye) showed initial and 24-hour survival that was intermediate
between the high and low values for the previously mentioned species. Redbreast
sunfish and largemouth bass mean 24-hour control survival was 99 and 91 percent,
respectively, compared to 59 and 56 percent for bigmouth buffalo and walleye,
respectively (Table 6). Due to low numbers of bigmouth buffalo, only the two-
and four-minute impingement series were tested.
A three-way ANOVA was used to evaluate the effect of the fish handling com-
ponents on initial and adjusted 24-hour survival for these four species (see Appen-
dix A). Table 7 is a summary of the ANOVA results in Appendix A. A significant
effect of impingement on both initial and adjusted 24-hour survival was observed
for all four species. For each species, except walleye, mean percent initial and
adjusted 24-hour survival values were significantly different among impingement
durations (based on Duncan's multiple range test). In each case survival was
inversely related to impingement duration (Table 7). Walleye usually showed
highest initial survival at four minutes impingement and highest 24-hour survival
at two minutes impingement (Table 7).
Only largemouth bass were significantly affected by air exposure in both
initial and 24-hour survival (Table 7). Air exposure showed a significant effect
on 24-hour survival only of redbreast sunfish and walleye while air exposure showed
a significant effect on initial survival only of bigmouth buffalo (Table 7). With
the exception of walleye, mean survival for 3 minutes air exposure was usually
lower than for either zero (impingement only) or one minute air exposure (Table 7).
However, based on results of Duncan's multiple range test, these differences were
not always significant.
Spilling did not have a consistent effect on survival. Lower mean survival
(both initial and adjusted) was occasionally associated with spilling for a par-
ticular species and at certain impingement durations and air exposures (Table 7).
However the results of the ANOVA indicated that spilling did not have a signifi-
cant effect on either initial or adjusted 24-hour survival for any of the four
species (Table 7).
The initial hypothesis was that a screen system which minimized air exposure
by providing a reservoir of water during travel to the spill position would repre-
sent a near-optimum system. In order to evaluate this hypothesized "best" screen
system, survival of impingement plus spill from a wet screen was compared with
"impingement only" survival using an ANOVA nested among impingement durations
(Table 8).
This test provided a comparison of survival associated with minimal handling
on a vertical traveling fine-mesh screen with "impingement only" survival.
Impingement would be associated with any fish screen employing the impinge-release
concept. . A significant main effect for initial and/or adjusted 24-hour survival
was observed for three species. Walleye showed higher average 24-hour adjusted
survival with "impingement plus spilling" compared to impingement only. Large-
mouth bass and redbreast sunfish showed lower average adjusted 24-hour survival
with impingement plus spilling. The main effect for redbreast sunfish and big-
mouth buffalo was most pronounced at the four minute impingement duration and at
the two-minute impingement duration for largemouth bass.
25
-------
TABLE 6. SUMMARY RESULTS OF FOUR SPECIES OF LARVAL FISH WHICH SHOWED
MODERATE TO HIGH SURVIVAL RESPONSE TO TEST CONDITIONS ON A
LABORATORY MODEL FINE-MESH TRAVELING SCREEN. DASH DENOTES
NO OBSERVATION.
Impingement Duration
Average Percentage Initial and 24-hour Survival
1 rain 2 min 4 rain
Un* Ad3
In Un Ad
In Un Ad
Species
Test Conditions
Controls (99)
Impingement only
Impingement + Spill
from wet screen
Impingement + 1 min
air exposure
Impingement + 1 min
air exposure
+ spill
Impingement + 3 min
air exposure
Impingement + 3 min
air exposure
+ spill
Controls (91)
Impingement only
Impingement + spill
from wet screen
Impingement + 1 min
air exposure
Impingement + 1 min
air exposure
+ spill
Impingement + 3 min
air exposure
Impingement + 3 min
air exposure
+ spill
Redbreast Sunfish
99+ 99 98
91 86 86
98 90 89
99 93 93
96 92 91
80 77 77
79 73 74
71 68 67
75 73 73
69 60 61
97 88 88 51 46 46
Largemouth Bass
100 89 99
100 90 99
99 87 95
96 74 87
96 78 91
89 72 85
99+ 87 99
87 53 66
93 72 85
99 85 97
78 64 77
75 55 68
46 44 42
15 14 14
20 17 17
856
88 46 60
82 58 72
87 68 81
83 56 69
72 35 48
79 51 64
26
-------
TABLE 6. (Continued)
Average Percentage Initial and 24-hour Survival
Impingement Duration
Species
Test Conditions
Controls (59)
Impingement only
Impingement + spill
from wet screen
Impingement + 1 min
air exposure
Impingement + 1 min
air exposure
+ spill
Impingement + 3 min
air exposure
Impingement + 3 min
air exposure
+ spill
Controls (56)
Impingement only
Impingement + spill
from wet screen
Impingement + 1 min
air exposure
Impingement + 1 min
air exposure
+ spill
Impingement + 3 min
air exposure
Impingement + 3 min
air exposure
+ spill
1 min
In1 Unz Ad3 In
Bigmouth
99
92
100
99+
100
99+
2 min
Un
Ad
4
In
min
Un
Ad
Buffalo
54
52
54
72
68
59
93
91
91
100
98
98
93
92
'94
91
74
69
39
28
42
33
36
17
80
68
80
74
77
58
Walleye
100 21 68 80
99+ 59 99 90
99 68 100 89
99+ 40 85 89
99+ 20 68 89
99+ 15 62 91
42
47
48
56
49
40
86
93
93
97
93
87
100
100
100
100
100
99
41
55
42
43
40
36
89
99
88
90
87
83
Initial survival.
224-hour unadjusted survival.
324-hour adjusted survival.
27
-------
TABLE 7. SUMMARY OF ANALYSIS OF VARIANCE RESULTS OF IMPINGEMENT, AIR EXPOSURE,
AND SPILLING. S DENOTES SIGNIFICANT ANOVA AT a = 0.05. NS DENOTES
NOT SIGNIFICANT.
Species
Redbreast
Sunfish
Source
Impingement
Air Exposure
Spilling
Imp. Dur. x Air Exp.
Imp. Dur. x Spill
Air Exp. x Spill
Initial
S
NS
NS
NS
NS
NS
24-hr
S
S
NS
NS
NS
NS
Largemouth
Bass
Initial
S
S
NS
S
NS
NS
24-hr
S
S
NS
NS
NS
NS
Bigmouth
Buffalo
Initial
S
S
NS
S
S
S
24-hr
S
NS
NS
NS
S
NS
Walleye
Initial
S
NS
NS
NS
NS
NS
24-hr
S
S
NS
S
NS
NS
TABLE 8. SUMMARY OF ANALYSIS OF VARIANCE (ANOVA) RESULTS COMPARING "IMPINGE-
MENT PLUS SPILL FROM THE WET SCREEN" WITH "IMPINGEMENT ONLY" (THIS
REFERRED TO AS "MAIN") NESTED OVER IMPINGMENT DURATIONS (LISTED AS
"NESTED"). S DENOTES SIGNIFICANCE OF THE EFFECT AT a = 0.05,
NS DENOTES NOT SIGNIFICANT.
Source
Redbreast
Sunfish
Largemouth
Bass
Species
Bigmouth
Buffalo
Walleye
Initial 24-hr Initial 24-hr Initial 24-hr Initial 24-hr
Main
Nested
NS
S
S
S
S
S
S
S
NS
NS
NS
S
NS
NS
S
NS
28
-------
Evaluation of Approach Water Velocity
The five species tested showed high initial and 24-hour adjusted survival
under most experimental conditions (Figure 5). All five species were tested using
a two-way ANOVA design including approach velocity and impingement duration as
independent variables.
All five species showed a close similarity between initial and 24-hour
adjusted survival values (Figure 5). This indicates that nearly all "test-
induced" mortality occurred within a comparatively short period of time (usually
less than 1 hour). Additional mortality which occurred during the holding period
was accounted for by the holding mortality experienced by the respective control
groups.
For smallmouth bass, black buffalo, and river carpsucker, approach velocity,
impingement duration, and the interaction between velocity and duration all had a
significant effect on both initial and 24-hour adjusted survival. For all three
experiments, the interaction effect was characterized by a more pronounced decrease
in survival at the longest duration and highest velocity (Figure 5).
For walleye, no significant differences in either initial or 24-hour adjusted
survival was observed for either approach velocity or impingement duration. How-
ever, a slight decrease in mean survival values was seen at the highest impingement
duration and slot velocity (Figure 5). For largemouth bass, only impingement dura-
tion had a significant effect (P = 0.03) on survival. Approach velocity and the
interaction of duration and velocity had no significant effect on survival of
largemouth bass.
Evaluation of Sprays
1. Adherence of larvae after passing through emergent spray.
Several tests were conducted without sprays to determine if impinged fish
adhered to the screen panel during emergence. The need for a spray at the screen
emergence position was apparent for most species. For both the flat vertical and
curved screens nearly all fish that impinged during screen submergence remained
attached to the screen fabric after the panel was raised out of the water.
Species which have large larvae (e.g., channel catfish, paddlefish) would not
adhere to the screen and would therefore not require an emergent spray.
Two levels of adherence were observed: (1) those that adhered to the screen
without penetrating the mesh and (2) those that penetrated the mesh. In most cases
the fish had not penetrated the mesh but were attached because of the adhesive
properties associated with the wet fish and wet screen fabric. The emergent spray
was usually very effective in rinsing those fish adhered to the screen into the
tray.
In other cases, individuals were entrapped in the mesh. In this case the
posterior end of the fish was observed protruding through the mesh with the
head preventing the fish from passing through the screen. The emergent spray
was ineffective in rinsing these entrapped larvae out of the mesh and into the
tray.
29
-------
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-------
Probably the most important single factor affecting entrapment was the stout-
ness of the fish. Based on earlier testing, cross sectional dimension appeared
to be more important than total length alone in determining whether larvae passed
through the screen (Tomljanovich et al. 1977). Similarly, in the 1979 tests length
alone did not account for entrapment. For example the two shortest species (striped
bass and bluegill) 5.4 mm and 5.8 mm mean total lengths, respectively, did not
experience any entrapment in the screen.
longer species that experienced some entrapment in the mesh included black
buffalo (mean total length =7.1 mm), bigmouth buffalo (mean total length =7.1 mm,
and river carpsucker (mean total length - 6.6 mm). Each of these species have
long threadlike bodies. The head region is typically largest with decreasing cross
sectional area from the head to caudal region.
A consistent pattern was not found to explain the reason(s) for larvae being
entrapped in the mesh. At the lowest approach velocity at least 25 percent of
the 5-day-old black buffalo were entrapped in the mesh. However, at 30.5 cm/s and
61.0 cm/s the fish were not entraped for any of the three impingement durations.
This suggests that at the lowest velocity the fish were able to move about while
impinged. In so doing they may have positioned their bodies to be more suscepti-
ble to going through the screen openings (this phenomenon was observed in the tests
conducted during 1976). At age 8 dayg none df this same group of fish, which was
tested at 23.0 cm/s was entraped in the screen, but were readily rinsed into the
tray.
In contrast to the results with black buffalo, 3-day-old walleye showed
approximately 6 percent entrapment at the highest velocity (61 cm/s) and no
entrapment at 15.0 and 30.5 cm/s. Two-day-did walleye tested at 23.0 cm/s
experienced about 8 percent entrapment.
A second group of walleye (age 4 days) was tested with clogged and clean high
and low lip curved, and inclined (60°) screens. In all of the tests the fish and
weeds readily were washed into the screen panel tray.
A third group of walleye larvae (age unknown) similarly did not experience
any entrapment in the mesh but were readily transferred to the tray with the
assistance of the emergent spray. Similarly, all largemouth and smallmouth bass
(ages unknown) were rinsed into the trough after passing through the emergent spray.
Seven-day-old bigmouth buffalo were tested exclusively with the curved screen
comparing the effect of the high tray lip, which produced a considerable eddy in
the screen panel, and a low lip which resulted in little, or no eddy formation.
With the high lip no bigmouth buffalo were entrapped in the mesh. With the low
lip approximately 25 percent were entrapped in the mesh.
Using the flat vertical screen, 4-day-old quillback were easily rinsed into
the tray at 23.0 cm/s approach velocity and 4 minutes impingement. Most fish moved
to the tray as the screen emerged so that few remained adhered when the panel
approached the spray.
River carpsucker were tested extensively from age 3-6 days. Three-day-old
larvae experienced a high percentage entrapment at two minutes impingement
(23.0 cm/s approach velocity) and a higher entrapment rate at four minutes
impingement (numbers not available).
32
-------
Four-day-old river carpsucker were tested at 2, 4, and 8 minutes impinge-
ment at 61.0, 30.5, and 15.0 cm/s approach velocity, using the flat vertical
screen. Also, two screen travel speeds (4.3 m/min and 6.4 m/min) were used.
None of the fish tested entrapped in the screen. Average adherence after
passing through the emergent spray ranged from 0 to 25.5 percent. High per-
centage adherence was associated with 8 minutes impingement, high screen speed,
and 61.0 cm/s approach velocity. Average adherence ranged from 0 to 4.5 percent
after 2 minutes impingement and from 0.6 to 6.2 percent after 4 minutes impinge-
ment. A clear relationship of approach velocity and adherence was not apparent.
Adherence was often greater at 30.5 cm/s than at 15.0 or 61.0 cm/s. Comparison
of high and low screen speed showed that adherence was equal to or greater for
the higher screen speed at all impingement durations for both 61.0 and 15.0 cm/s
approach velocity but less at 30.5 cm/s approach velocity.
Five-day-old river carpsucker were tested at 4 and 8 minutes impingement
using the curved screen with high and low lip, and the flat vertical screen.
All tests were conducted at 23.0 cm/s approach velocity. None of the fish
impinged or adhered with the high lip screen. On the contrary, with the low
lip screen after 4 and 8 minutes impingement 87 and 92 percent of the fish,
respectively, adhered. Many of these fish were entrapped in the mesh. In
tests with the flat screen 9 percent of the larvae adhered to the screen after
passing through the emergent spray.
Six-day-old river carpsucker were used to compare the effectiveness of
the sprays on a clogged screen compared to a clean screen. The flat vertical
screen was approximately 30 to 40 percent covered with fragments of three
species of aquatic plants found in the Holston River. After 8 minutes impinge-
ment nearly all weeds were washed into the tray and about 28 percent of the
fish were entrapped in the screen mesh. With the clean screen tests, average
adherence was 26 percent.
2. Adherence after passing through overhead spray.
In general, if the fish did not become entrapped in the mesh, they spilled
out of the tray readily. Occasionally one to several individuals adhered to a
corner of the panel or to the metal tray lip. Table 9 depicts the results of
tests using the overhead spray with 11 nozzles. For those fish that became
entrapped in the mesh, the overhead spray was not effective in removing them.
Several tests were conducted to evaluate spilling after the screen was
covered with aquatic plants. In initial tests of curved screens with high and
low lip, the weeds, water, and fish were readily emptied at the spill position.
In another series of tests using the lower volume emergent spray, much of
the weed content adhered to the screen. At the spill position the overhead
spray washed them into the tray but most of them did not spill into the fish
return trough. With a heavy load of clogging the higher volume emergent spray
would be required.
In general, there did not appear to be a significant problem with spilling.
Each panel type would require a slightly different spray design to spill most
effectively.
33
-------
TABLE 9. AVERAGE PERCENTAGE OF FISH THAT REMAINED IN THE TRAY AFTER PASSING
THROUGH THE SPILL POSITION AND SPRAY. ALL TESTS WERE CONDUCTED
WITH A CLEAN SCREEN.
Average Percentage
Species Screen Panel Type Remaining in Tray
Largemouth Bass Flat (vertical) 0
Curved (standard lip) 0.8
Smallmouth Bass Flat (vertical) 0.8
Curved (high lip) 3.4
Curved (low lip) 1.0
Walleye Curved (high lip) 0
Curved (low lip) 2.4
Flat (vertical) 0.7
Curved (standard lip) 0.8
Bluegill Flat (vertical) 0.3
3. Effect of emergent and overhead sprays on survival of fish larvae.
Initial testing with the mechanical sprays installed showed that only minimal
spray pressures were needed to adequately rinse the larvae and weeds into and out
of the trays. It was necessary to limit the force of the emergent spray to prevent
forcing adhered larvae out of the screen panel. It soon became apparent from
observation that sprays alone would not be an important source of mortality. Con-
sequently, tests comparing survival using higher pressure sprays were not conducted.
Sprays at the overhead position would have less effect on survival than the emergent
spray since the fish are already in the tray of water and the spray does not hit
directly on them.
Evaluation of Screen Panel Design
1. Adherence
Adherence of larvae during screen panel emergence has aready been discussed
for flat vertical and curved screens. It was shown that an emergent spray was
necessary for rinsing larvae into the panel tray. Walleye and striped bass
larvae were tested to determine if the use of flat angled screens would be self-
rinsing and thus obviate the need for an emergent spray.
Tests with walleye larvae and weeds showed that a partially clogged 60-degree
screen required an emergent spray to rinse fish and debris into the water holding
tray whereas tests conducted only with fish did not require an emergent spray.
With the clean screen the larvae did not impinge but moved down the angled screen
into the tray portion of the panel. Here they were agitated in an eddy for the
4-minute duration of the test. With the clogged screen the eddy was eliminated
and the larvae impinged against the screen.
34
-------
Comparison of adherence of five-day-old striped bass between 4.3 and 6.4
m/min screen speeds and between 60 degree and 30 degree angle screen panels
revealed some clear differences. Lowest average adherence was shown for the
faster screen speed for both 60 and 30 degree panels (Table 10). Paired t-tests
showed a highly significant difference (P=<0.001) in adherence between screen
speeds and a significant difference (P=<0.01) between screen panels. Adherence
was lower on the 60 degree screen.
TABLE 10. COMPARISON OF PERCENTAGE ADHERENCE OF STRIPED BASS LARVAE BETWEEN
SCREEN ANGLES AND BETWEEN SCREEN TRAVEL SPEEDS. NO SPRAY WAS
USED DURING SCREEN PANEL EMERGENCE.
Percentage Adherence
60 degree screen 30 degree screen
Screen speed (m/min) 4.3 6.4 4.3 6.4
Replicates 35 81 24 72
33 95 20 76
31 89 30 73
33.0 88.3 24.7 73.7
2. Spilling
Each panel shape showed a slightly different pattern of spilling. Lip angle
and height as well as inside shape of the tray determined at which point during
the overhead travel of the screen the tray would begin to spill and at what point
it would completely empty its contents. Most screen panels would empty before
spilling onto the sprocket shaft. Modification(s) may be required for some unique
screen panels not tested in these experiments in order to achieve the desired
spilling performance.
3. Survival
Table 11 presents the results of five screen combinations that were compared
to evaluate the effect of panel shape on survival. The predominant comparison of
a high lip curved screen with a low lip curved screen was designed to compare the
survival of larvae that stayed in the eddy produced behind the high lip with sur-
vival of larvae that were impinged against the low lip screen panel. Of the five
species tested, average 24-hour adjusted survival was significantly greater for
one species on the high lip curved screen and for two species on the low lip
curved screen.
The flat vertical screen was compared with each of the low lip curved, high
lip curved, and standard lip curved screens. Average 24-hour adjusted survival
for the flat vertical screen was greater in all six comparisons in which this
panel was evaluated. These differences were significant (P < 0.05) in three
comparisons. Greatest mean differences existed for those tests in which the
35
-------
TABLE 11. EFFECT OF PANEL SHAPE ON SURVIVAL OF FISH LARVAE TESTED ON A LABORATORY
MODEL FINE-MESH TRAVELING SCREEN. TESTS USUALLY INCLUDED IMPINGEMENT
FOLLOWED BY SPILLING INTO THE FISH RETURN TROUGH. TESTS WERE CONDUCTED
WITH A CLEAN SCREEN. HL C = HIGH LIP CURVED, LL C = LOW LIP CURVED,
FV = FLAT VERTICAL, SL C = STANDARD LIP CURVED, FI 60 = FLAT INCLUDED
60°.
Average Percent Survival
Species
River carpsucker
Bigmouth buffalo
Striped bass
Smallmouth bass
Walleye
River carpsucker
Smallmouth bass
Black buffalo
Largemouth bass
Largemouth bass
Smallmouth bass
Walleye
Walleye
Impingement
Duration (min)
8
4
2
8
4
4
8
2
4
8
8
4
4
HL C
85.3
76.5
69.4
68.8
50.9
LL C
85.9
93.3
SL C
83.3
81.7
77.4
HL C
68.8
HL C
50.9
HL C
63.7
Initial
vs LL C
58.9
75.7
56.8
93.3
63.7
vs FV
95.0
97.9
vs FV
72.6
94.2
93.2
vs FV
97.9
vs FI 60
18.6
vs FI 60
18.6
24-hour
HL C
84.9
71.2
81.3
64.2
57.3
LL C
83.0
91.9
SL C
55.2
79.0
76.4
HL C
64.2
HL C
57.3
LL C
70.4
Adjusted
vs LL C
56.9*
72.5
67.8
91.9*
70.4
vs FV
89.2
95.5
vs FV
62.0
94.4*
91.7*
vs FV
95.5*
vs FI 60
42.0
vs FI 60
42.0*
'"Denotes significance at P<0.05.
36
-------
larvae did not impinge on one of the two screens being compared, e.g., the high
lip curved vs flat vertical. Mean values were similar for those tests in which
the larvae impinged on both screens.
Comparison of walleye survival associated with a flat inclined 60° screen
compared with the low lip curved screen showed significantly lower 24-hour adjusted
survival for the inclined screen. In these tests the larvae resided in an eddy
in the inclined screen but impinged against the curved screen.
The results of the panel shape comparisons suggested that for most groups of
fish tested, a screen panel that impinges the fish is preferred over a screen panel
that allows the larvae to tumble and swim about in an eddy. Apparently the harmful
effects of tumbling in a turbulent zone behind the lip is greater than the effects
associated with impingement against the screen fabric.
Observations of Test-Induced Shock or Overt Signs of Stress
During the course of testing, observations on the larvae's post-test condi-
tions were often noted to determine the length of time required for the larvae to
regain normal behavior, i.e., the behavior observed prior to the test. For example,
most of the species tested were swimming actively in the holding container prior
to testing, but some fish showed no swimming activity for some period after the
test. Often these fish lay on the bottom (either motionless or twitching) for a
period of several minutes to an hour or more before resuming their normal swimming
posture.
Seven-day-old bigmouth buffalo exposed to "impingement only" for four minutes
on the high lip and low lip curved screens appeared quite stressed 30 minutes after
the tests. Approximately 75 percent of the fish were alive at the time of the
initial survival determination.
Three groups of walleye likewise showed overt signs of stress following test-
ing. Two-day-old walleye exposed to 1, 2, and 4 minutes "impingement plus spilling"
began to recover shortly after being spilled and siphoned into coolers. Initial
and 24-hour survival was very high for these fish.
In tests with another group of four-day-old walleye comparing the effect of
high and low lip curved screens, nearly all fish were lying on the bottom of the
coolers one hour after being subjected to four minutes "impingement plus spilling."
Somewhat fewer fish appeared to be stressed for these tests with the low lip
(impinging screen) than with the high lip (eddy-producing screen).
A third group of walleye (age unknown) subjected to two and four minutes
"impingement plus spilling" also showed some signs of stress following the test.
This group recovered within two hours. A greater percentage of fish in stress
was observed for those fish subjected to two minutes of being in an eddy on a
curved screen than for four minutes impingement against a flat screen. These
observations support the conclusion derived from survival results of screen panel
comparisons that impinging the larvae is preferred over allowing them to tumble
about in the screen panel.
A difference in post-test stress between 30.5 and 61.0 cm/s approach water
velocity was observed for smallmouth bass larvae. After both four and eight
minutes "impingement plus spilling" at 61.0 cm/s, nearly all fish were lying on
37
-------
the bottom of the cooler. Within an hour these fish either recovered (began
swimming) or died. After four and eight minutes "impingement plus spilling" at
15.0 cm/s velocity, there was much less evidence of test-induced stress. Most
fish were swimming actively at the end of the four-minute tests. At the end of
the eight-minute tests about half the number of fish were swimming.
Several other hardier species showed no or little overt stress immediately
after those tests which included four minutes or less impingement time. River
carpsucker showed signs of stress after eight minutes impingement but appeared to
recover within a few minutes after being siphoned into the coolers.
Observations of Longer Than 24-Hour Delayed Mortality
For one group of walleye and the quillback, observations were made on longer
than 24-hour survival. After the 24-hour dead count of three-day-old walleye
tested at two velocities and three impingement durations, the remaining live
larvae were left in the coolers for an additional 48 hours. The fish were not
fed during this period and no water was added to make up for considerable leakage
in the coolers. Despite the seemingly unfavorable conditions (by the end of 72
hours most of the coolers contained only a few centimeters water depth) there were
very few additional dead larvae. Most appeared to be livelier than at the 24-hour
mortality count.
Similarly, quillback larvae were held for 96 hours after testing without being
fed and without replacing water in the coolers. Nearly all the fish were very
lively at the end of 96 hours.
Evaluation of Predictive Value of Laboratory Tests
Tests were usually conducted on the earliest life stages that could be
obtained for each species. It appeared that, for a given species, the ability
of the fish to survive the impinge-release process would be positively correlated
with its size and age. It was assumed that by testing the youngest life stages
the results would represent minimum survival for the species. Few species of
larval fish have survived beyond several days under laboratory conditions. This
has precluded adequately evaluating the effect of size/age on survival. Often
the larvae that survive up to a few weeks in the laboratory grow weaker with age.
Tests with these fish can lead to erroneous conclusions about their expected
survival on a prototype screen operating in the natural environment.
Results of the few species that thrived under laboratory conditions or that
were obtained in their natural habitat as early juveniles suggested that when the
fish which are fragile as young larvae attained early juvenile stage they were
very capable of withstanding the conditions imposed by an impinge-release system.
Since only very limited age ranges of larvae were usually tested for most species,
it is impossible to provide an expected survival rate for a species. Each life
stage of the larvae, obtained in the condition that would be expected under natural
conditions, would need to be tested in order to accurately estimate survival for
that species.
Test results for most species which showed high control survival and
which were tested within a few days of hatching or obtained from the natural
habitat probably closely approximate the percentage survival that would be
expected on a prototype screen.
38
-------
SECTION 4
FISH AVOIDANCE CONCEPT
MATERIALS AND METHODS
Description of Test Facility
The test facility used in this experiment simulated a range of water velocity
conditions that could typically exist in a river or stream. The facility was not
designed to model a prototype but rather to test the response of larvae to several
combinations of approach and slot velocities, screen orientation, and amount of
exposure to screen (length of screen).
The test apparatus consisted of a plexiglas flume (Figure 6) 11.9 m long by
39.4 cm wide by 39.4 cm deep. Half of the flume contained five consecutive 1.2 m
long sections, each containing a flat slotted screen panel (Figure 7). Water
could be withdrawn from one or more of the test sections through the slotted
screen. Two directions of withdrawal were obtained by placing the screen either
horizontally to form the bottom of the flume or vertically to form one wall.
Smith (1977) described the design of the test flume and screening medium in
detail.
Water temperature control was unavailable in the test flume. Water used in
the laboratory was supplied from a 757 m3 sump located beneath the laboratory. A
few times each year the sump may be drained and refilled with chlorinated tap water.
To remove the chlorine and make the water suitable for testing fish, the water
was aerated by circulating it for several days through one or more test flumes or
models. Since the water supply is changed infrequently, chlorine toxicity is rarely
a problem. Water temperature is dependent on ambient weather conditions as well
as the extent to which the several test flumes and models are operated. Flume
temperatures were usually a few degrees warmer than holding water.
Acquisition and Pretest Holding of Fish Larvae
The same methods of obtaining and holding test fish described for the
impinge-release tests were used for the fish avoidance experiments.
Description of Test Procedures
1. Test fish were transferred from "Living Stream" holding tanks to the
Engineering Laboratory for testing via a 12 2 plastic container.
2. To adjust the temperature of the holding water to that of the flume water,
the transfer container was immersed in flowing flume water. Water tem-
perature was monitored periodically, and testing was not begun until
39
-------
MANOMETER
_, »FICE INLET
FLOW METER
FISH CHARGING
PIPE
VERTICAL
TEST
COLLECTION NET
BYPASSED
FISH
HORIZONTAL
TEST SCREEN
BYPASS FLOW
CONTROL VALVE
AND FLOW
—METER
CONTROL VALVE FOR
GRAVITY FLOW THROUGH
SCREENS
COLLECTION NET
FOR ENTRAINED
FISH
WATER RETURN CHANNEL
WEIR BOXES (5) FOR
CONTROL OF FLOW
THROUGH SCREENS
Plgure 6.
-------
HORIZONTAL SLOT
ORIENTATION
VERTICAL SLOT
ORIENTATION
FLOW
FLOW
APPROACH FLOW PARALLEL
TO THE SLOT
SLOT
APPROACH FLOW PERPEN-
DICULAR TO THE SLOT
WEDGE -WIRE
SUPPORT
WIRE
Figure 7. Stainless steel wedge wire screens used in laboratory test flume to evaluate the "fish
avoidance" concept of protecting fish larvae at water intakes.
-------
the temperature in the container was within 2 C of the flume tem-
perature. During the temperature adjustment period, the holding water
was continuously aerated, and fish were carefully observed for overt
signs of thermally induced stress. The first year of study showed the
fish to be livelier and more responsive when not subjected to long
acclimation periods, thus the second year of testing eliminated this
step. Ho signs of thermal shock were observed during any of the tests.
jerimental conditions for a particular test (screen position, screen
slot width, and water velocities) were established (Table 12). This
was accomplished by adjusting the valves which controlled the gravity
flow of water through the screens. The flow was metered by measuring
the water level in each of the five weir boxes (Figure 6). The water
depth in the downstream end of the flume was held at approximately 37
cm (14.6 in) during all tests. Therefore, approach velocity (upstream
of the test screens) and bypass velocity (downstream of the test screens)
were a function of through-screen velocity. The open area of all screens
¥as approximately 22 percent, regardless of slot width.
&. In each test all fish were introduced into the flume near the wall of
vertical test screens. Flow on this side represented the entrainable
portion, and all larvae introduced into this flow were subject to
entrapment. Therefore, any fish that bypassed the screens would have
shown some avoidance response. This method of introducing the fish and
evaluating the avoidance response represents the majar deviation between
the two year's studies. In the first year fish were introduced as uni-
formly as possible throughout the water column and proportion of fish
entrained was compared with proportion of flow entrained.
5, Depending on availability and size of each species, from several hun-
dred to more than 1,000 individuals were poured from a 1,000 mil beaker
into the flume via a glass tube of 2.5 cm diameter (Figure 6). As the
fish drifted downstream they were either entrained, impinged, or drifted
past (avoided) the screens. Entrained individuals were retrieved from
a fine-mesh catch cup located in each test section weir box (Figure 6).
Fish which avoided entrapment were retrieved from a collection cup fitted
to the cod end of a cone-shaped collection net located downstream of
the screen sections (Figure 6). Entrained fish were counted immediately.
Fish which avoided entrapment were usually more numerous and were pre-
served and counted at a later date. Selected samples of this latter
group were used to obtain average total lengths of test fish. Very few
fish impinged against the screens. If a fish was too large to fit
through the screen opening, it was usually able to avoid impingement.
The few fish that were impinged were included with the entrained frac-
tion. A three replicate test design was used throughout the study.
Numerical Analyses
Appendix B details the numerical analyses performed on the first year's data
and gives graphic presentations of the results for each species tested.
Using these data as a base, the second year of study evaluated the effect of
additional experimental variables on avoidance of entrapment. The variables tested
included illumination, slot orientation, through-screen velocity, slot width, fish
42
-------
TABLE 12. EXPERIMENTAL VARIABLES TESTED IN THE "FISH AVOIDANCE" CONCEPT FLUME
STUDIES.
Year Tested
Variable 1 i
Screen orientation (vertical) X X
Screen orientation (horizontal) X
Slot orientation (perpendicular to flow) X
Slot orientation (parallel to flow) X X
Slot width (0.5 mm) X X
(1.0 mm) XI
(2.0 mm) XX
Diel period (day) X 1
Diel period (night)
Bottom refuge (present)
Bottom refuge (absent) X X
Screen length (number of 1.2 m test sections) X
Velocities
Through Screen 7.5 cm/s (.25 fps) X X
15 cm/s (.50 fps) X X
22.9 cm/s (.75 fps) X
Bypass 7.6 cm/s (.25 fps) X
15 cm/s (.50 fps) X
30.5 cm/s (1.0 fps) X
61 cm/s (2.0 fps) X
Fish age (selected species) X
Species tested
Muskellunge (Esox masquinongy) X
Channel catfish (Ictalurus punctatus) X X
Bluegill (Lepomis macrochirus) X X
Largemouth bass (Micropterus salmoides) X X
Smallmouth bass (Micropterus dolomieui) X
Striped bass (Morone saxatilis) X
Walleye (Stizostedion vitreum) X X
Paddlefish (Polyodon spathula) X
Northern pike (Esox lucius) X
White sucker (Catostomus commersoni) X
Striped x white bass hybrid (Morone sp.) X
Sauger (Stizostedion canadense) X
43
-------
age, presence of a bottom refuge, and screen length (Table 12). Limited time
and numbers of test fish required that emphasis be placed on certain "key"
independent variables. These key variables were slot velocity, screen length,
slot orientation, and diel period.
Avoidance of entrapment was the basic dependent variable in the second
yearrs testing. Avoidance, expressed as a simple percentage value, was calcu-
lated in two ways. The effect of the experimental variables on avoidance for
the entire screen was examined first, treating all five screen sections as a
single screen unit. Avoidance was then calculated separately for each screen
section as the percentage of available fish which avoided entrainment and impinge-
ment. The total number available at each screen section was reduced by the
number of fish entrapped in the preceding (upstream} screen sections. Comparison
of avoidance values by screen, from upstream to downstream, was used to estimate
the effect of screen length on avoidance.
Multifactor analysis of variance (ANOVA) designs were used to examine effects
of experimental independent variables on avoidance. In all cases, percentage
values were transformed using an arcsin function (Sokal and Rohlf 1969). All
averages presented as part of the ANOVA results were calculated with the trans-
formed data and reconverted to the original percentage units. These averages
are derived means and are not "raw" arithmetic averages. Comparisons among
these values are therefore limited to the statistical analysis. Techniques
available from the Statistical Analysis System (SAS), General Linear Models
Procedure (Barr et al. 1976) were used to transform the data and to calculate
the statistics for the multifactor ANOVA designs. Duncan's Multiple Range tests,
used to compare mean avoidance among levels of each significant effect, were
also calculated by SAS procedures. Although use of the Duncan's test in analyses
which generally included only two levels of each main effect might appear redun-
dant, this procedure provided information on the magnitude and relationship of
significant differences indicated by the analyses of variance. Determination
of significance in all statistical tests was based on an a-level of 0.05.
RESULTS AND DISCUSSION
The ability of seven species of fish in the larval to early juvenile stages
to avoid entrainment through stationary slotted screens was tested the first
year of the fish avoidance study. The mean total lengths of these fishes ranged
from 5.6 mm to 21.5 mm. These species exhibited a wide range in behavior, which
affected their overall performance in the test flume. Within-replicate variabil-
ity was usually high for most species and was probably due to behavioral charac-
teristics which resulted in nonhomogeneous distributions of the fish in the
water column.
The results of the 296 separate test conditions (excluding the first experi-
ment with muskellunge) showed that for all three slot widths, the fishes tested
could avoid entrapment to some extent (Appendix B).
The initial hypothesis that larval fish are incapable of detecting and
responding to entraining flows was rejected. All of the larval fish species
tested, except very young muskellunge, showed some ability to avoid entraining
currents under most experimental conditions. Many species showed considerable
avoidance, often resulting in nearly all of the fish in a given test avoiding
entrapment (Appendix B).
44
-------
During the second year of study, 243 tests were conducted. Larvae of the
nine species tested ranged in age from 3 to 18 days (Table 13), with average
total lengths ranging from 5.7 mm (5-day-old striped bass hybrid) to 14.7 mm
(4-day-old paddlefish). Size of larvae was more dependent on species than age.
Paddlefish, northern pike, white sucker, and channel catfish were longer than
the older striped-white bass hybrid and sauger tested.
Table 14 shows the combinations of variables that were tested and percent
avoidance for all screen sections treated as a single unit. Since the objective
of the study was to evaluate the effect of several variables rather than to
simply determine conditions that would result in high avoidance for "problem
species," those conditions which would yield either low or high entrapment were
not tested. A large range in average avoidance among combinations of variables
was observed for all species.
Avoidance Response to Total Length of Screen
Nine different experimental designs were applied to the data, eight of
which included slot velocity as an independent variable (Table 15). ANOVA tech-
niques indicated that all independent variables had a significant effect on
avoidance for nearly every species. Interaction between these variables also
affected avoidance in many cases.
1. Independent Variable = Slot Velocity
Northern pike was the only species tested with this design. Slot velocity
had a highly significant effect on avoidance. Duncan's multiple range test
indicated that mean avoidance at slot velocity 7.5 cm/s (80.5 percent) was signi-
ficantly greater than at 15.0 cm/s (14.9 percent). The observed low avoidance
of this species at the high slot velocity is consistent with adaptations to
the natural habitat during young life stages. Flooded meadows and marshes,
characterized by very still or slowly moving water, are utilized as nursery
habitat by northern pike (Eddy and Underbill, 1974).
2. Independent Variables = Slot Velocity x Slot Orientation
This design was tested for five species (Table 15). Slot velocity and
slot orientation both had a significant effect on avoidance. Duncan's multiple
range tests indicated that the lower slot velocity resulted in significantly
higher avoidance (Table 16). The effect of slot orientation, however, was spe-
cies dependent. Greater avoidance occurred with the vertical slot orientation
for white sucker, channel catfish, and sauger, whereas striped-white bass hybrid
and largemouth bass showed significantly greater avoidance with the horizontal
orientation.
The slot velocity x slot orientation interaction effect was significant
for white sucker and channel catfish (Table 17). In each case, the effect of
slot orientation was greater at the lower slot velocity. At the higher velocity
fish apparently have little chance of escaping once contact is made, regardless
of slot orientation. At the lower slot velocity the probability of escaping
is apparently greater with the vertical slot orientation. This was expected
since in this case the slot is oriented perpendicular to the length of the fish.
45
-------
TABLE 13. AGE AND MEAN SIZE OF FISH TESTED IN THE "FISH AVOIDANCE" LABORATORY
FLUME. TOTAL LENGTHS OF 100 INDIVIDUALS WERE MEASURED FROM
SELECTED SAMPLES FOR EACH DAY OF TESTING.
Species
Age
(days)
Mean
Total Length
(mm)
Range
Faddlefish
Northern pike
White sucker
Channel catfish
striped x white bass
Bluegill
Largemouth bass
Sauger
Walleye
4
5
6
3
4
5
9
10
3
4
5
6
5
6
13
14
16
12
13
17
18
5
9
4
5
14.7
15.0
14.2
13.8
13.5
14.0
14.3
14.0
11.4
12.2
12.9
13.4
5.7
5.6
6.3
6.5
7.3
10.3
10.7
13.0
14.2
7.5
8.4
8.8
9.0
13.0-16.0
13.5-16.5
13.0-15.5
13.0-14.5
12.0-14.5
13.0-16.0
13.0-15.5
13.0-15.0
10.0-12.5
10.5-14.0
11.0-14.5
12.0-14.5
5.0-6.0
5.0-6.0
4.5-7.0
5.0-7.5
6.0-8.0
9.0-13.0
9.0-16.0
12.0-16.0
12.0-22.5
7.0-8.0
7.5-9.5
7.0-9.5
8.0-10.0
46
-------
TABLE 14. SUMMARY OF ALL "FISH AVOIDANCE" TESTS THAT WERE CONDUCTED IN THE 2ND TEST YEAR. VALUES
DENOTE THE MEAN PERCENTAGE (ARITHMETRIC AVERAGE) OF FISH THAT AVOIDED THE ENTIRE 6.1 m LENGTH
OF TEST SCREEN. EACH VALUE USUALLY REPRESENTS A MEAN OF THREE REPLICATES. IN A FEW CASES
DIFFERENT AGES WERE COMPARED, AND THE MEAN IS BASED ON SIX OR NINE TESTS.
Slot
Width
(mm)
0.5
0.5
0.5
0.5
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
Slot
Orientation
Perpendicular
Perpendicular
Perpendicular
Perpendicular
Perpendicular
Parallel
Perpendicular
Parallel
Perpendicular
Parallel
Perpendicular
Parallel
Perpendicular
Parallel
Perpendicular
Parallel
Perpendicular
Parallel
Perpendicular
Parallel
Perpendicular
Parallel
Perpendicular
Parallel
Diel
Period
Day
Night
Day
Night
Day
Day
Night
Night
Day
Day
Night
Night
Day
Day
Night
Night
Day
Day
Day
Day
Night
Night
Day
Day
Bottom
Refuge
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
Yes
No
No
No
No
Yes
Yes
Slot
Vel.
(cm/s)
7.5
7.5
15.0
15.0
7.5
7.5
7.5
7.5
15.0
15.0
15.0
15.0
7.5
7.5
7.5
7.5
7.5
7.5
15.0
15.0
15.0
15.0
15.0
15.0
Percentage Avoidance
Larval Fish Species1
W
100
-
96
-
97
88
87
42
47
61
14
3
-
-
-
-
-
-
-
-
-
-
-
—
SBH
972
9i2
422
252
85
89
28
-
32
35
-
-
„
..
-
-
_
-
-
-
-
-
-
—
CC
*PB
-
-
-
100
-
-
_
99+
-
-
—
98
44
-
60
-
90
32
11
-
12
-
57
WS
_
-
-
-
99+
-
91
-
86
-
71
—
92
76
96
-
86
-
49
52
38
-
71
—
S
w.
-
-
-
97
97
76
-
67
86
6
—
-
-
-
-
-
-
-
-
-
-
-
—
BG
_
-
-
-
99+
-
-
-
99+
-
-
—
94
-
81
-
-
-
82
-
46
-
-
—
P
_
-
-
-
-
-
-
-
-
-
-
—
93
84
86
59
-
-
75
60
51
28
-
—
1MB
_
-
-
-
-
-
-
-
-
-
-
—
94
96
-
-
-
-
69
75
-
-
-
—
NP
_
-
-
-
-
-
-
-
-
-
-
—
81
-
-
-
-
-
15
-
-
-
-
—
I. W = Walleye, SBH = striped x white bass, CC = Channel catfish, WS
P = Paddlefish, LMB = Largemouth bass, NP = Northern pike.
2. Only four sections of screen were available for these tests.
= White sucker, S = Sauger BG = Bluegill,
-------
TABLE 15. A SUMMARY OF THE EXPERIMENTAL DESIGNS USED TO INVESTIGATE "FISH AVOIDANCE" DURING THE SECOND
TEST YEAR. THE FOLLOWING ABBREVIATIONS WERE USED TO REPRESENT THE EXPERIMENTAL VARIABLES:
SW = SLOT WIDTH, SO = SLOT ORIENTATION, DP = DIEL PERIOD, BR - BOTTOM REFUGE, SV = SLOT
VELOCITY, AND FA = FISH AGE. AN "X" IN A VARIABLE COLUMN INDICATES THAT THIS VARIABLE WAS
TREATED AS AN INDEPENDENT VARIABLE IN ONE OF THE NINE EXPERIMENTAL DESIGNS USED.
oo
Experiment
No.
I
2
3
4
5
6
7
8
9
Potential Test Variables
SW
2.0 mm
2.0 mm
1.0 mm
2.0 mm
1.0 mm
2.0 mm
2.0 mm
1 .0 mm
0.5 mm
1.0 mm
X
X1
X1
2.0 mm
2.0 mm
2.0 mm
1.0 mm
SO
vert
X
X
X
X
horiz
vert
vert
vert
vert
vert
vert
vert
horiz
vert
horiz
vert
DP
day
day
day
X
X
X
X
X
X
X
X
day
day
day
day
day
day
BR
no
no
no
no
no
no
no
no
no
no
no
no
no
X
X
no
no
SV FA
X
X
X
X
X
X
Y M
X
X
7.5 cm/s
X
X
X
X
X
X X
X X
Species Tested
northern pike
white sucker, channel catfish, largemouth bass
striped x white bass sauger
paddlef ish
walleye
channel catfish
bluegill
sauger
striped x white bass
striped x white bass
white sucker
channel catfish, bluegill
walleye
channel catfish
white sucker
white sucker
striped x white bass, sauger
1Channel catfish and bluegill were tested with the 1.0 and 2.0 mm slot widths while walleye were tested with
the 0.5 and 1.0 mm slot widths.
-------
TABLE 16. RESULTS OF DUNCAN'S MULTIPLE RANGE TESTS FOR SIGNIFICANT MAIN
EFFECTS OF ANOVA ANALYSES FOR SLOT VELOCITY AND SLOT ORIENTATION.
Mean Avoidance (%)
Species
White sucker
Channel catfish
Striped x white
bass
Largemouth bass
Sauger
Slot Velocity
7.5
82.3
68.4
87.9
95.5
98.2
( cm/ s )
15.0
51.4
18.1
31.9
72.4
89.9
Slot
Vertical
74.3
74.5
59.5
84.2
96.7
Orientation
Horizontal
65.3
27.8
68.9
88.0
92.6
TABLE 17. MEAN AVOIDANCE FOR THE COMBINED LEVELS OF SLOT VELOCITY AND SLOT
ORIENTATION FOR TWO SPECIES WHICH SHOWED SIGNIFICANT INTERACTION
IN A TWO-WAY ANOVA DESIGN (SLOT VELOCITY AND SLOT ORIENTATION).
Slot Velocity (cm/s)
15.0
15.0
7.5
7.5
Slot Orientation
Vertical
Horizontal
Vertical
Horizontal
Mean
White Sucker
48.8
52.7
91.9
76.3
Avoidance (%)
Channel Catfish
32.3
10.9
97.6
43.9
3. Independent Variables = Slot Velocity x Slot Orientation x Diel Period
This design was tested with paddlefish and walleye (Table 15). All
three independent variables showed significant main effects for avoidance by
both species. Duncan's multiple range test indicated significantly higher mean
avoidance values for low slot velocity, vertical slot orientation, and daylight
period (Table 18).
49
-------
TABLE 18. RESULTS OF DUNCAN'S MULTIPLE RANGE TESTS FOR SIGNIFICANT MAIN EFFECTS
OF ANOVA ANALYSES FOR SLOT VELOCITY, SLOT ORIENTATION, AND DIEL PERIOD.
Species
Paddlefish
Walleye
Slot Velocity
7.5
82.0
83.2
(cm/s)
15.0
54.6
29.1
Mean Avoidance (%)
Slot Orientation
Vertical Horizontal
78.5 59.4
68.7 49.8
Diel Period
Day Night
79.5 58.1
76.0 40.4
Interaction effect for slot velocity x slot orientation was significant
only for walleye and was similar to that described previously; i.e. , the effect
of slot orientation was greater at the lower slot velocity (Table 19).
Diel period x slot orientatioft interaction effect was significant for both
paddlefish and walleye. The effect of slot orientation was apparently greater
during night tests. Both species were more vulnerable to entrapment by the
parallel slot screen at night. The remaining two-way interaction term, slot
velocity x diel period, was not significant in either analysis.
TABLE 19. MEAN AVOIDANCE FOR COMBINED LEVELS OF SLOT VELOCITY AND SLOT ORIENTA-
TION (WALLEYE) AND DIEL PERIOD AND SLOT ORIENTATION (PADDLEFISH AND
WALLEYE) FOR SPECIES WHICH SHOWED SIGNIFICANT INTERACTIONS IN A
THREE-WAY ANOVA DESIGN (SLOT VELOCITY, SLOT ORIENTATION, AND DIEL
PERIOD).
Slot Velocity (cm/s)
Slot Orientation
Mean Avoidance (%)
Walleye
15.0
15.0
7.5
7.5
Diel Period
Day
Day
Night
Night
Vertical
Horizontal
Vertical
Horizontal
Vertical
Horizontal
Vertical
Horizontal
Paddlefish
85.3
72.9
70.6
44.0
30.8
27.4
93.3
69.2
Walleye
79.4
72.3
56.2
23.1
50
-------
4. Independent Variables = Slot Velocity x Diel Period
These were the predominant experiments used to examine the effect of diel
period (Table 15). With the sole exception of diel period for channel catfish,
both independent variables had a significant effect on avoidance. Duncan's
multiple range tests showed the usual response to slot velocity (i.e., lower
slot velocity resulted in significantly higher mean avoidance (Table 20).
TABLE 20. RESULTS OF DUNCAN'S MULTIPLE RANGE TESTS FOR SIGNIFICANT MAIN
EFFECTS OF ANOVA ANALYSES FOR SLOT VELOCITY AND DIEL PERIOD.
Mean Avoidance (%)
Slot Velocity Ccm/s) Diel Period
Species 7.5 15.0 Daylight Night
Channel catfish
striped x white bass
Bluegill
Sauger
49.4
94.5
88.5
87.1
11.1
33.9
65.7
24.6
27. 81
77.2
88.9
74.8
37. 11
64.4
65.0
44.6
*Not significantly different.
All species except channel catfish showed significantly higher mean avoid-
ance during daylight tests (Table 20). The response of channel catfish is con_
sistent with the described habits of this species. Channel catfish are primarily
nocturnal. Pflieger (1975) noted that during early life stages, young channel
catfish seek secluded areas characterized by semidarkness. Specific behavioral
adaptations associated with nocturnal activity probably account for the higher
(although not significant) avoidance during night testing.
These results indicated that orientation to visual stimuli is important in
the overall avoidance response. The interaction effect of slot velocity and
diel period was not significant for any species.
5. Independent Variables = Diel Period
This experiment was conducted with striped x white bass (Table 15). As in
the case of the previous design, diel period was shown to have a significant
effect on avoidance. Duncanrs multiple range test indicated that mean avoidance
during daylight (77.8 percent) was significantly greater than during night (28.0
percent).
51
-------
6. Independent Variables = Slot Velocity x Diel Period x Slot Width
This design was tested only with white sucker (Table 15). All three inde-
pendent variables had a significant effect on avoidance. Low slot velocity, day-
light period, and small slot width again resulted in higher avoidance (Table 21).
TABLE 21. RESULTS OF DUNCAN'S MULTIPLE RANGE TESTS EXAMINING SIGNIFICANT MAIN
EFFECTS OF ANOVA ANALYSES FOR SLOT VELOCITY, DIEL PERIOD, AND SLOT
WIDTH AS INDEPENDENT VARIABLES.
Species
White sucker
Slot Velocity (cm/s)
7.5 15.0
95.3 63.4
Mean Avoidance (%)
Diel Period
Day Night
86.4 78.7
Slot
1.0
89.7
Width (mm)
2.0
74.2
Slot velocity x diel period interaction was not significant in this experi-
ment. The remaining two interaction terms (slot width x diel period and slot
width x slot velocity) each showed a significant effect on avoidance (Table 22).
The effect of diel period was greater for 1.0 mm than for 2.0 mm slot width
screens and a greater effect of slot velocity was shown for the larger slot size.
Therefore, for white sucker, avoidance appeared to be related to visual stimuli
and was strongest for the 1.0 mm screen.
TABLE 22. MEAN AVOIDANCE FOR THE COMBINED LEVELS OF SLOT WIDTH AND DIEL PERIOD
AND SLOT WIDTH AND SLOT VELOCITY: FOR WHITE SUCKER, WHICH SHOWED
SIGNIFICANT INTERACTION EFFECTS IN A THREE-WAY ANOVA DESIGN (SLOT
VELOCITY X DIEL PERIOD X SLOT WIDTH).
Slot Width (mm)
Diel Period
Mean Avoidance (%)
White Sucker
1.0
1.0
2.0
2.0
Slot Width (mm)
1.0
1.0
2.0
2.0
Day
Night
Day
Night
Slot Velocity (cm/s)
15.0
7.5
15.0
7.5
94.9
82.9
74.3
74.1
White Sucker
79.7
96.5
43.7
93.9
52
-------
7. Independent Variables = Slot Velocity x Slot Width
This design was tested with three species (Table 15). Both slot velocity
and slot width had a significant effect on avoidance in each analysis. Duncan's
multiple range tests showed significantly higher avoidance associated with the
lower slot velocity and narrow slot widths (Table 23).
TABLE 23. RESULTS OF DUNCAN"S MULTIPLE RANGE TESTS FOR SIGNIFICANT MAIN
EFFECTS OF ANOVA ANALYSES FOR SLOT VELOCITY AND SLOT WIDTH.
Mean Avoidance (%)
Species
Slot Velocity (cm/s)
7.5 15.0
Slot Width (mm)
0.5
1.0
2.0
Channel catfish
Bluegill
Walleye
99.4
98.3
99.4
79.5
95.0
77.4 99.9
99.9
99.9
79.4
74.5
88.9
The slot width x slot velocity interaction effect was significant in every
analysis (Table 24). As in the preceding analysis, the effect of velocity was
more pronounced with the larger slot width. The larvae in these tests were too
large to pass through the smaller slots and were able to avoid impinging on the
screens.
TABLE 24. MEAN AVOIDANCE FOR THE COMBINED LEVELS OF SLOT WIDTH AND SLOT
VELOCITY FOR THREE SPECIES WHICH SHOWED SIGNIFICANT INTERACTION
IN A TWO- WAY ANOVA DESIGN (SLOT VELOCITY X SLOT WIDTH).
Mean Avoidance (%)
Slot Width (mm) Slot Velocity (cm/s) Channel catfish Bluegill Walleye
0.5
0.5
1.0
1.0
2.0
2.0
15.0
7.5
15.0
7.5
15.0
7.5
_
-
99.8
100.0
32.3
97.6
„
-
98.9+
99.9+
81.9
94.3
95.8
100.0
46.7
97.5
-
-
8. Independent Variables = Slot Velocity x Bottom Refuge
This design examined the effect of a bottom refuge on avoidance for white
sucker and channel catfish (Table 15). Slot velocity and bottom refuge had a
53
-------
significant effect on avoidance for both species; significantly higher avoidance
occurred for low slot velocity and a bottom refuge (Table 25).
TABLE 25. RESULTS OF DUNCAN'S MULTIPLE RANGE TESTS FOR SIGNIFICANT MAIN
EFFECTS OF ANOVA ANALYSES FOR SLOT VELOCITY AND BOTTOM REFUGE.
Mean Avoidance (%)
Slot Velocity (cm/s) Bottom Refuge
Species 7.5 15.0 Present Absent
White sucker
Channel catfish
79.8
71.0
59.3
40.5
79.3
73.3
65.3
27.8
Increased avoidance with the bottom refuge was especially apparent for
channel catfish. These results are consistent with the tendency of this
species to remain very close to the bottom of the flume. The slot velocity x
bottom refuge interaction term was not significant for either species.
9. Independent Variables = Slot Velocity x Fish Age
This design was an attempt to determine the extent that swimming ability
(assumed to be directly related to fish age in this experiment) contributed to
fish avoidance of the wedge-wire screen. Three species were tested (Table 15).
Slot velocity and fish age significantly affected avoidance in each analysis.
Duncan's multiple range tests indicated significantly higher mean avoidance for
low slot velocity and older fish (Table 26).
TABLE 26. RESULTS OF DUNCAN'S MULTIPLE RANGE TESTS FOR SIGNIFICANT MAIN
EFFECTS OF ANOVA ANALYSES FOR SLOT VELOCITY AND FISH AGE.
Mean Avoidance (%)
Slot Velocity (cm/s)
Species 7.5 15.0
White sucker
Striped x white
Sauger
White sucker
bass
5 days 6 days
60.1
76.3
86.2
97.4
Fish Age
9 days 10 days
70.2
52.7
32.0
72.8
13 days 15
days
striped x white
bass 54.9 59.5
Sauger 74.8 96.7
54
-------
For two of the three species, the interaction effect of slot velocity
and fish age was significant (Table 27). In both cases, the entrapment effect
of velocity was greater for young fish. However, since growth is also a factor,
this interaction may partially reflect the slot width x slot velocity effect
described previously. The results suggested that a prototype would probably
entrap a relatively narrow age (size) range of fish.
TABLE 27. MEAN AVOIDANCE FOR THE COMBINED LEVELS OF FISH AGE AND SLOT VELOCITY
FOR TWO SPECIES WHICH SHOWED SIGNIFICANT INTERACTION IN A TWO-WAY
ANOVA DESIGN (SLOT VELOCITY AND FISH AGE).
Mean Avoidance
Fish Age (days) Slot Velocity (cm/s) White Sucker Walleye
5
5
9
9
10
10
15.0
7.5
15.0
7.5
15.0
7.5
39.3
77.4
-
-
64.8
75.2
42.0
95.1
93.1
99.0
-
-
Avoidance Response to Each Individual Screen Section
Nearly all of the experimental designs just discussed were also tested
using avoidance of individual screen sections as the dependent variable. This
analysis provided an additional independent variable, screen section position.
In each experimental design, avoidance of each 2.1 m long screen section showed
nearly identical patterns of response to the independent variables as previously
described for the dependent variable of combined screen sections.
In every analysis, screen section position in the flume had a significant
effect on avoidance. Duncan's multiple range tests showed that highest avoid-
ance always occurred for one of the first (upstream) three screens. In most
analyses, the subset of mean avoidance from one or more of these first three
sections (numbers 1 to 3) was significantly higher than mean avoidance on the
other screen sections.
Decreased avoidance of the downstream screens is probably due to decreased
current velocity at the end of the flume. Figure 8 illustrates the effect of
water withdrawal through the test screens on velocity in the flume for the two
slot velocities. The higher slot velocity resulted in lower velocity at the
downstream end of the flume. The velocity at the upstream end of the flume was
sufficiently high at both slot velocities to preclude any of the larvae from
maintaining a position in the current. However, some species were able to swim
for appreciable lengths of time in the last screen section, thus increasing the
period of susceptibility to entrapment. This was especially true for the higher
slot velocity tests, in which the velocity in the flume was minimal and in some
cases negative.
55
-------
w
tl
O -
•SLOT VELOCITY = I 5»0 cm/s
61.0
UJ LJ
HI
30.5 -
Ul
0
SLOT VELOCITY = 7.5 cm/s
34
SCREEN LENGTH,m
CO
2 Ujf>
-^ ii
LJ O
O UJ
< DC
CE 13
uj cn
> <
< UJ
Figure &.. Average water velocity in the "fish avoidance" flume (based on nine cross-
sectional measurements at six locations) from upstream end of test section
#1 to downstream end of test section #5 for two slot velocities.
-------
Net avoidance from upstream to downstream was used to examine avoidance
response with respect to screen length (Figure 9). Each slot velocity was
plotted separately since this was the major independent variable and because of
the strong effect of slot velocity x screen section interaction on avoidance.
Each species showed a large difference in avoidance between slot velocities.
At the higher slot velocity three species showed a nearly linear decline in
avoidance from upstream to downstream. On the other hand, white sucker,
largemouth bass, and walleye were distinctly affected by slot velocity at the
downstream-most section. Avoidance decreased markedly between the fourth and
fifth sections at the higher slot velocity for these species, probably due
largely to reduced velocity in the flume which enabled the fish to remain in
the downstream test section for extended periods of time.
To better understand the importance of swimming on the avoidance response,
several tests were repeated using the same individuals after they were dead and
preserved in formalin. White sucker, which have relatively large, filiform
larvae, and walleye, which have smaller, stouter larvae, were tested in daylight
with the vertical slot orientation and no bottom refuge. White sucker were
tested with the 2.0 mm slot, and walleye were tested with the 1.0 mm slot. The
live larvae clearly showed significantly greater avoidance (based on a paired
t-test) for both slot velocities (Table 28).
TABLE 28. COMPARISON OF MEAN AVOIDANCE BETWEEN DEAD AND LIVE LARVAE OF TWO
SPECIES AT EACH SLOT VELOCTIY.
White sucker Walleye
Slot Velocity (cm/s) Dead Live Dead Live
7.5
15.0
69
4
92
49
12
18
97
47
Dead larvae showed high impingement, as opposed to live fish. The walleye
results were questionable owing to greater dead fish "avoidance" with 15.0 cm/s
slot velocity compared to 7.5 cm/s slot velocity. The results of tests with
dead fish indicated that a portion of each avoidance value for live fish tests was
due to one or more factors not related to swimming ability. The large difference
in dead white sucker "avoidance" between slot velocities suggested that turbulence,
velocity in the flume, and/or percent of total flow entrained through the test
screens affected the portion of avoidance not related to swimming of live larvae.
57
-------
PADDLEFISH
WHITE SUCKER
CHANNEL CATFISH
Ln
00
UJ
o
z
<
Q
6
lOOr
80
60
40
20
0
g 100
g 80
cr
UJ
°- 60
40
20
SLOT VELOCITY =
7.5 cm/s
SLOT VELOCITY
15.0 cm/s
J L
STRIPED BASS HYBRID
LARGEMOUTH BASS
WALLEYE
1
\
\
-llOO
80
60
40
20
-1 100
80
60
40
20
0
SCREEN SECTIONS
Figure 9, Effect of screen length (number of adjacent 1.2-m-long screens) on entrapment avoidance by larval fish. Each
Vne represents cumulative entrapment (expressed as percentage net avoidance) from upstream (screen 1) to down-
stream (screen 5). All values are averages over several test conditions (slot width, slot orientation, diel perio4
-------
REFERENCES
Barr, A. J., J. H. Goodnight, J. P. Sail, and J. T. Helwig. 1976. A User's
Guide to SAS, 76, SAS Institute, Inc., Raleigh, NC 329 pp.
Eddy, S. and J. C. Underbill. 1974. Northern Fishes. University of Minnesota
Press, Minneapolis. 414 pp.
McSwain, Kenneth R. and R. E. Schmidt. 1976. Gabions, perforated pipe and
gravel serve as fish screens. Proceedings of the American Society of
Civil Engineers. 46(5):73.
Pflieger, William L. 1975. The Fishes of Missouri. Missouri Department of
Conservation. Western Publishing Co. 343 pp.
NJ Prentice, Earl F. and F. J. Ossiander. 1974. Fish diversion systems and
:" biological investigation of horizontal travelling screen Model VII.
Proc. 2nd workshop on eatrainment and intake screening. EPRI Report
No. 15, pp 205-213.
Richards, Richard T. and M. J. Hroncich. 1976. Perforated-pipe water intake
for fish protection. Journal of Hydraulics Division, Proceedings of the
American Society of Civil Engineers, Vol. 102, No. HY2. pp 139-149.
Sazaki, M., W. Heubach, and J. E. Skinner. 1972. Some preliminary results
on the swimming ability and impingement tolerance of young-of-the-year
steelhead trout, king salmon, and striped bass. Final Report for Anad.
Fish. Act Proj. Calif. AFS-13. 30 pp.
Smith, M. 1977. Fish impingement test facility using Johnson well screens
TVA internal report No. 0-7428.
Sokal, R. R. and F. J. Rohlf. 1969. Biometry. W. H. Freeman and Company,
San Francisco. 776 pp.
Stober, Q. J., C. H. Hanson, and P. B. Swierkowski. 1974. A high capacity
sand filter for thermal power plant cooling water intakes, Part I:
Model studies and fouling control techniques. In: Entrainment and
Intake Screening, Proceedings of the Second Entrainment and Intake
Screening Workshop. Report No. 15:317-334.
Tomljanovich, D. A., J. H. Heuer, and C. W. Voightlander. 1977. Investigations
on the protection of fish larvae at water intakes using fine-mesh screening.
TVA Technical Note B22. Norris, TN 53 pp.
Yeager, B. L. 1979. Induced spawning and hatchery techniques for the quillback
and river carpsuckers. Prog. Fish. Cult, (in print).
59
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GLOSSARY
Approach Velocity—The calculated or measured velocity of water in the flume
upstream of the test screen through which water is withdrawn.
Avoidance (Avoided)—Refers to a significant difference between observed and
expected proportion of fish which bypass the test screen in which observed
is greater than expected.
Bypass Velocity—The velocity of the remaining portion of the total flow of water
in the test flume after a portion has been withdrawn through the test screen.
Bypass velocity is calculated or measured at a point immediately downstream
of the test section being used in a particular experiment.
Entrainment—The transport of fish through a test screen by water current.
Entrapment--The arithmetic sum of number of fish entrained and number impinged.
Immediate Survival—The proportion of the retained fish which were alive
approximately one hour after a test.
Impingement--The process of a fish being forced against a test screen by water
current and unable to escape throughout the duration of a test.
Larval Fish—Developmental stage of fish defined as extending from the period of
hatching to full development of fin rays. Used throughout this report to
refer to fish a few days to a few weeks of age. This period of development
is divided into the prolarval stage (from time of hatching until absorption
of yolk sac is complete, and fish begin actively feeding on plankton) and
post-larval stage (larval stage after absorption of yolk sac).
Long-term Survival—The proportion of the retained fish of a given test which were
alive at the end of a 48-hour post-impingement holding period.
Pooled—Refers to the summing of the three replicate observations for each
test such that the totals are treated as representing a single observation.
Proportion Bypassed—Refers to that proportion of the total number of fish
released at the upstream end of the flume which are collected downstream
at the test screens.
Retention—The nonpassage of fish through a test screen when forced against it
by the water current.
Screening--Used interchangeably with retention.
Screen Opening--The clear opening distance in millimeters between any two parallel
and adjacent wires of a screen. Only square opening woven wire screens were
used in impinge-release testing. Slotted wedgewire screens were used in fish
avoidance testing.
Test Duration—The elapsed time in minutes from when the first fish of a test group
was observed impinged or entrained until the current was stopped.
60
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SUMMARY OF IIITIA-L FEASIBILITY
61
-------
APPENDIX A
IMPINGE-RELEASE CONCEPT
SUMMARY OF INITIAL FEASIBILITY STUDY
TEST FACILITY
The test facility provided for (1) instantly applying preselected velocities
through a pressurized test chamber, (2) instantly reducing the velocity to zero,
(3) interchanging screens of different material and mesh size, (4) collecting
fish which passed through the test screen, and (5) safely removing fish retained
in the test chamber.
The following experimental variables were examined during the first year.
Experimental Variables
Screen opening (mm) 0.5, 1.0, 1.3, 1.8, 2.5
Approach water velocity (cm/sec) 15, 31, 46, 58, (0.5, 1.0, 1.5,
1.9 fps)
Impingement duration (min)
Fish species:
0.5, 1, 2, 4, 8, 16
Common Name
Jewelfish cichlid
Threadfin shad (juveniles)
Golden shiner
Fathead minnow
White sucker
Channel catfish
Striped bass
Bluegill
Smallmouth bass
Largemouth bass
Walleye
Scientific Name
Hemichromis bimaculatus
Dorosoma petenense
Notemigonus crysoleucas
Pimephales promelas
Catostomus commersoni
Ictalurus punctatus
Morone saxatilis
Lepomis macrochirus
Micropterus dolomieui
Micropterus salmoides
Stizostedion vitreum
TEST PROCEDURES
A group of fish were placed in the test chamber, the chamber was pressurized,
and a preselected velocity was applied for one of the preselected impingement
62
-------
durations. The larvae either impinged against the test screen or passed through
it into a collection net. At the end of the test the velocity was reduced to
zero, the chamber depressurized, and the impinged fish siphoned into a styrofoam
cooler. Dead fish were removed and preserved; live fish were held for evaluating
delayed test-induced mortality.
RESULTS
Two primary dependent variables were percentage of fish retained by the test
screens and percentage survival of the retained or impinged fish. Table A-l
presents a summary of percentage of fish retained by screen opening size and
average size of test fish.
Fish shape ranged among species from threadlike to stout. Body length alone
was not a good indicator of percentage retention. Cross-sectional dimension was
more important than length in determining whether or not the fish passed through
the screen opening.
Average retention for the 0.5 mm opening screen was greater than 99 percent
for the four species with the smallest body depths: walleye (1.4 mm), large-
mouth bass, (1.4 mm), white sucker (1.4 mm), and striped bass (1.0 mm). For screen
openings larger than 0.5 mm, average percentage retention appeared to be largely
dependent on average body depth. For each screen, the minimum mean body depth
which resulted in essentially 100 percent retention was fairly well defined as
follows:
Screen Opening (mm) Body Depth (mm)
0.5 <0.7
1.0 1.8
1.3 2.4
1.8 2.8
2.5 4.6
A field study, in which fine-mesh screens were attached to a conventional
vertical traveling screen, showed that the 0.5 mm opening screen impinged at
least twice as many fish as the 1.0 and 2.0 mm opening screens.
Velocity did not significantly affect percentage retention for the two
smallest openings, but was significant for the 1.3, 1.8, and 2.5 mm screens.
This might indicate that at the smaller openings most of the fish tested were
sufficiently large that velocity increments had no effect in "squeezing" the
fish through the openings; whereas, for similar size fish but larger screen
openings, increased velocity forced more fish through the openings.
Table A-2 and Figures A-l and A-2 present a summary of percentage survival
of the retained fish.
Survival of the control groups of each species gave some estimate of the
mortality caused by handling and/or post-test holding. These data indicated
that holding mortality was negligible (survival at 48 hours > 90 percent) for
all species except striped bass and walleye. For these fragile species, sur-
vival of the control groups was characterized by large variability.
63
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TABLE A-l. PERCENT RETENTION OF FISH ON FINE-MESH SCREENS1
Square mesh
screen opening Number
Species (mm) of tests
Jewelfish cichlid
Threadfin shad
Golden shiner/
fathead minnow
White sucker
Channel catfish
Striped bass
Bluegill
Smallmouth bass
1.0
1.3
0.5
2.5
1.0
1.3
0.5
1.0
1.3
1.3
1.8
2.5
0.5
1.0
1.3
1.3
1.8
2.5
1.3
1.8
2.5
5
6
19
18
12
12
12
36
19
1
24
45
102
66
14
1
13
16
12
24
9
Average
retention
100.0
68.1
100.0
100.0
97.0
65.0
99.9
79.5
30.6
100.0
99.2
66.3
99.1
29.3
24.0
100.0
99.4
72.7
99.9
82.4
30.6
95% confidence
limits
Lower
100.0
58.7
100.0
100.0
93.2
50.3
99.8
71.3
16.3
97.7
51.6
98.7
24.1
8.0
97.6
58.5
99.6
66.4
9.2
Upper
100.0
76.8
100.0
100.0
99.3
78.2
100.0
86.4
47.2
99.9
79.5
99.4
34.9
44.8
100.0
84.9
100.0
94.0
57.8
Weighted mean size (mm) of
all entrained and impinged
test fish
Length
7.2
7.3
39.5
37.9
11.7
11.8
14.1
13.8
13.6
14.8
15.7
17.7
6.2
6.6
7.7
13.8
14.3
14.3
10.8
12.0
13.4
Width
1.5
1.6
4.2
3.6
1.5
1.5
1.2
1.2
1.3
2.8
3.0
3.4
0.7
0.9
1.0
2.0
2.2
2.1
2.0
2.1
2.3
Depth
1.8
1.8
8.9
8.2
1.8
1.7
1.4
1.4
1.4
2.8
2.8
3.3
1.0
1.0
1.3
2.9
3.0
2.9
2.5
2.7
2.9
-------
TABLE A-l. (continued)
Species
Largemouth bass
Walleye
Square mesh
screen opening Number
(mm) of tests
0.5
1.0
1.3
1.8
0.5
1.0
1.3
17
26
39
9
12
18
16
Average
retetention
99.5
84.7
80.4
38.2
99.7
89.7
11.0
95% confidence
limits
Lower
98.5
71.8
71.1
17.6
98.6
84.5
8.2
Upper
100.0
94.2
88.2
61.4
100.0
94.0
14.3
Weighted mean size (mm) of
all entrained and impinged
test fish
Length
6.8
7.7
8.9
10.3
9.6
9.8
10.3
Width
1.1
1.3
1.6
1.7
1.1
1.3
1.3
Depth
1.4
1.6
1.9
2.2
1.4
1.5
1.6
ON
Ln
1. Current velocities (0.5-1.5 fps; 15.2-46.7 cm/s) and test durations (0.5-16.0 min) were combined for
each species and screen opening.
-------
TABLE A-2. MEAN PERCENT SURVIVAL OF FISH IMPINGED ON FINE-MESH SCREENS
(SCREEN OPENINGS AND VELOCITIES COMBINED) AND CONTROL GROUPS.
Hours Fish
Held After Test Duration (minutes)
Species Test
Jewelfish cichlid
Threadfin shad
Golden shiner/
Fathead minnow
White sucker
Channel catfish
Striped bass
Bluegill
Smallmouth bass
0
6-12
24
48
0
6-12
24
48
0
6-12
24
48
0
6-12
24
48
0
6-12
24
48
0
6~I2
24
48
0
6-12
24
48
0
6-12
24
48
.5
65
53
53
53
100
99
97
95
99
94
94
94
99
97
97
97
1003
1003
iOO3
100s
79
52
35
22
100
100
100
100
IOO3
99
99
98
1
81
65
59
59
100
97
96
93
95
92
91
90
96
94
93
92
99
99
99
93
85
52
36
25
IOO
IOO3
IOO3
IOO3
99
99
99
88
2
91
83
83
83
IOO3
85
77
74
91
90
90
90
99
98
98
98
100
100
IOO
100
80
46
34
^T
<&* S
IOO3
IOO3
IOO3
IOO3
99
98
98
98
4
85
76
76
76
98
72
69
69
89
87
87
84
90
84
84
80
IOO3
IOO3
99
99
72
37
22
18
99
99
99
99
98
98
98
9?
8
90
69
69
69
75
44
44
43
90
86
86
86
95
80
80
77
IOO3
99
99
99
51
20
13
10
97
97
97
97
IOO3
IOO3
IOO3
98
16
43
30
30
30
55
26
21
20
89
81
81
79
74
40
37
36
97
90
88
88
7
1
<1
<1
96
96
96
96
IOO3
98
98
96
Mean
Survival1
of Controls
(%)
NA
100
100
100
NA
100
98
98
NA
99
99
99
NA
100
100
100
NA
99.8
99.5
99.5
NA
82
56
44
NA
100
100
99
NA
100
100
100
L2
_
-
-
-
_
-
-
«.
-
_
100
100
100
98
97
97
70
38
30
_
-
-
100
100
100
u2
«
-
-
_
-
-
-
_
..
-
100
100
100
100
100
100
92
73
61
-
-
-
100
100
100
66
-------
TABLE A-2. (Continued)
Species
Largemouth bass
Walleye
Hours Fish
Held After
Test
0
6» 12
24
48
0
6-12
24
48
Test Duration (minutes)
,5
93
88
79
74
90
66
65
63
I
96
90
85
81
79
60
52
48
2
94
89
87
83
75
53
51
49
4
93
82
71
61
74
A 2
3S
38
8
93
S3
75
71
35
9
9
9
Mean
Survival1
16 of
70
62
54
52
9
2
2
2
Controls L
(1)
NA
99 97
96 91
93 88
IA
84
74
71
U*
100
99
97
-
_
_
1. 95 percent
2 . L and U rep
confidence limits
resent lower and
calculated
uppe
r 95 pei
onlv
rcent
i f n
conf
>3,
idence
limits, re
sspectively ,
about the mean control survivals.
Average survival greater than 99,49 but less than 100,00,
67
-------
-------
\
V
*%
\
-A
\>
^ *. 'i<,
\ % \
\ **
-------
Average survival following impingement varied greatly among species, rang-
ing from 100 percent to less than 1 percent. Two species (smallmouth bass,
bludgill) showed high survival under practically all test conditions.
Impingement duration was the predominant variable affecting initial and
long-term survival and showed a strong inverse relationship to survival for all
taxa which responded to the test conditions.
For five taxa which showed fairly high average survival, (juvenile thread-
fin shad, mixed minnows, white sucker, bluegill, largemouth bass) approach
velocity showed a significant inverse relationship to survival. Generally,
larger fish showed better survival than smaller fish of the same species.
CONCLUSIONS
The results of the initial laboratory and field study demonstrated the
relationships of percentage retention to screen opening size and the remaining
test variables. The relationships of survival of the screened fish to the test
variables were also well defined within the range of species and sizes tested.
Accurately predicting survival of all species and sizes of larvae
which would be retained on a prototype screen was not possible owing to the
(1) large differences in size and hardiness that would be found among species
in the natural environment and (2) additional sources of mechanical handling
mortality associated with screens used.
70
-------
APPENDIX B
FISH AVOIDANCE CONCEPT
SUMMARY OF INITIAL TEST YEAR
71
-------
APPENDIX B
FISH AVOIDANCE CONCEPT
SUMMARY OF INITIAL TEST YEAR
NUMERICAL ANALYSES
Table B-l outlines the combinations of test variables used for each species.
A replicated goodness-of-fit procedure was found to be applicable to the analysis
of the first year's experimental question. The "G" statistical parameter was
selected because of ease of calculation and because it allowed a precise deter-
mination of within-replicate variability or "heterogeneity" (Sokal and Rohlf
1969).
The expected proportions bypassed and entrapped were determined by the
unique bypass-slot velocity combination for each test. Differences between the
horizontal and vertical orientations were analyzed by comparing the observed
proportions of fish bypassed (pooled over replicate tests) with a paired t-test
(Ostle 1963). Figures B-l to B-8 present the results for each species tested.
Since the proportion of water entrained among bypass-slot velocity combi-
nations was not constant in this experiment, direct examination of the propor-
tion of fish bypassed as a means of comparing fish response among slot velocities
and between bypass velocities was not meaningful. Therefore a variable, which
was adjusted for the different expected entrainment values, was calculated
using the formula:
t, Pb - Pb
Pr = x—
1 - Pb
where Pr = "relative bypass," Pb = observed pooled proportion of fish bypassed,
/S.
and Pb = expected proportion bypassed (based on proportion of total flow entrained
through the screen for a given bypass-slot velocity combination). This variable
(Pr) represents relative bypass as the ratio of the observed bypass (Pb - Pb) to
s*
the maximum possible bypass described by 1 - Pb). Thus, a score of 1.00 for any
given test would indicate that all of the larvae had bypassed the screen, and a
score of 0.00 was obtained when the observed proportion bypassed was equal to the
expected proportion. A negative value indicated that a larger proportion was
entrapped than was predicted by the expected proportion. However, since relative
bypass was not bounded on the negative scale, the magnitude of a negative value
had little comparative meaning. Figures B-9 to B-20 graphically present this
relationship for the species tested.
72
-------
TABLE B-l. SPECIES AND VARIABLES TESTED DURING THE FIRST YEAR'S EXPERIMENT.
co
VARIABLES
Species
Largemouth Bass
Bluegill
Channel Catfish
Striped Bass
(test 1)
Striped Bass
(test 2)
Muskel lunge
Walleye
Smallmouth Bass
Slot Size
0.5 mm 1.0 mm 2.0 mm
X X
X
X X
XXX
X X
X
XXX
X X
Slot
Orientation
Horiz
X
X
X
X
X
X
X
X
Vert
X
X
X
X
X
X
X
X
Bypass Velocity
cm/s
7.5 15
X
X
X
X X
X
X X
X X
X
30.5 61.0
X X
X X
X X
X X
X X
X
X X
X X
Slot Velocity
cm/s
7.5 15.0
X X
X
X X
X X
X X
X
X X
X X
22.9
X
X
X
X
X
X
X
-------
BYPASS VELOCITY = 15.2 a/sec
1,9
8.9
a.s
SS.7
HI
8
H
§8,4
f,
0
1 8.3
8.2
9.1
88
—
«_. N
»
/
&
fa
2'
N,
S
ft
/
X
ra
1 ,
\
N
2^
5
|
2
7.6 15.2 22.9
SLOT VELOCITY (ci/sec)
BYPASS VaOCITY = 39.5 OI/SK
M
9.9
98
an 7
kit 7
i
3
ae.B
8
§8-5
H
1=
SM
a
a
s*
ls.3
82
9.1
8f;
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0
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1
B
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«
III
h
152
SLOT VELOCITY (O/M
229
9.8
S9.7
«
ID
(L
0
183
82
9.1
BYPASS VELOCITY = 61 a/sec
5*5*
76
15.2
SLOT VELOCITY (a/sec)
229
[] - VERTICAL f^ - HORIZONTAL > - EXPECTED PROPORTION BYPASSED
» DIFFERENCES BETUEEN EXPECTED AND OBSERVED VALUES SIGNIFICANT AT <* = 85 LEVEL
Figure B-l. Proportion of largemouth bass bypassed by slot width (denoted in
mm above each bar) and screen orientation for each slot and bypass
velocity.
-------
BYPASS VaOCITY = 15 2 o/sec
I.B
8,9
e.8
Se.7
W
M
£0.6
ge.s
H
1-
K0 ,
08.4
n.
0
£0.3
8.2
e.i
0 1
K
r *
N
X
2
V
i.
*
7/1
7.6 i5.2 22.9
SLfil VEUBm (ca/-
£
H
5
12
V
7.6 152 22.9 "" 7.6 15,2 22.9
SLOT VaOCITY ( SLOT VELOCITY («/we)
[] - VERTICAL ^ - HORIZOKTAL > - EXPECTED PROPORTION BYPASSED
> DIFFERENCES BETVEEN EXPECTED AND OBSERVED VALUES SIGNIFICANT AT « = 85 LEV!
Figure B-2.
Proportion of bluegill bypassed by slot width (denoted in mm above
each bar) and screen orientation for each slot and bypass velocity.
75
-------
BYPASS VELOCITY = 15 2 ct/«c
it «
1 8
89
88
387
M6
0
H
1-
1
0
8:83
82
8!
8.8
S
X
1
N
!
1
N
X
2^
1
1
>
i
I
2*
I
76 15 2 22.9
SLOT VELOCITY Cci/sec)
BYPASS VELOCITY * 38.5 ci/stc
BYPASS VELOCITY = 61 «/s«
1.9
8.9
8.8
S87
- EXPECTED PROPORTION BYPASSED
» DIFFERENCES BETUEEN EXPECTED AND OBSERVED VALUES SISNIFICANT AT«= 85 LEV!
Figure B-3.
Proportion of channel catfish bypassed by slot width (denoted in
mm above each bar) and screen orientation for each slot and bypass
velocity.
76
-------
BYPASS VELOCITY = 7 6 ci/a
BYPASS VELOCITY = 15 2 c*/sec
1 8
89
8.8
S8.7
«
«
186
m
§1.5
H
h
0
Z83
8.2
6.1
8 6
-
\
-
3
*
2
1
I
!
I
\
ft
1
X
1
c
X
7
1
I
ft
f?
I
'
'/<
1
i
%
2
]
i
*
>
5
2*
i
I
I
i
^
/ /f
7.6 15.2 229
SLOT VELOCITY (C./MC)
BYPASS VELOCITY = 38 5 or/sec
X
1.8
89
68
887
«
ID
186
a
?«5
H
ge<
i
0
18.3
62
81
8 8
V.
s
ft
X
*
1
1
1
V
5*
-
2*
5*
X X
1 2
>
5*
1
2*
|
i
1
76 152 229
SLOT VaOCITY (en/sec)
69
88
Se;
196
g>
1-
"tti
08.4
H
0
6.2
8 1
5 , 5 ,
«
m
§
M
\£
^
///7
^77
I'
Zl
152
SLOT VaOQTY (en/sec)
BYPASS VELOCITY = 61 cn/stc
229
1 8
69
88
g8.7
10
10
^66
0
H
h
a
0
8.2
81
8.8
- ,.s' ; .• 5' 5' . 5'
-
—
j_
77
!
i_!_ *
1
1
'/
\
s
—
i
X
IT/
!
X C
!
LL
!
s
o
i
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7y
/I
i
'/'/
/,/,
77,
'///,
n
'///.
77,
vA
W
/'/
77
'/'
V1/
II ll
152
229
[] - VERTICAL ^ - HORIZONTAL > - EXPECTED PROPORTION BYPASSED
^Denotes differences between expected and observed values significant at a = 0.05
level.
Figure B-4.
Test 1
Proportion of striped bass bypassed by slot width (denoted in mm
above each bar) and screen orientation for each slot and bypass
velocity.
77
-------
BYPASS VELOCITY = 15 2 (Wsec
1.8
89
8.8
Se.7
M
01
18.6
0
S»-5
H
gB4
0
8:8.3
8.2
81
8 8
X
J,
I
»
t
1
i
//
*
*v
2
X
771
1
(/
//
-v
S
1*
X X
2 2
7.6 15 2 22.9
SLOT VELXITY (CH/MC)
BYPASS VELOCITY = 38.5 M/«C
BYPASS VaOCITY = 61 «/«
1.8
89
8.8
887
ID
186
a
H
i-
i
0
8.2
8.1
to
•\
J\
2'
1
1
>
1*
*
2
1*
i
i
•s,
X
2
1
1
1.8
8.9
88
Se.?
w
t)
18.6
a
H
I
0
{83
8.2
8.1
ee
-
•
I
!
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*
2 I L
I
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N
1
2
!
1
7.6
15.2
SLOT VELXITY («/sw)
SLOT VELOCITY (M/S«)
[] - VERTICAL ^j - HORIZONTAL > - EXPECTED PROPORTION BYPASSED
» DIFFERENCES BET1IEEN EXPECTED AM) OBSERVED VALUES SIGNIFICANT AT<*= 65 LEVa
Figure B-5-
Test Z
Proportion of striped bass bypassed by slot width (denoted in mm
above each bar) and screen orientation for each slot and bypass
velocity.
78
-------
BYPASS VaOCITY = 7 6 oi/sec
89
88
SB?
B
If)
186
ID
H
1-
o8<
1
0
8:83
82
8 1
6 0
_
•v
2*
,
«
2
76 152 229
SLOT VELOCITY CC./SK)
BYPASS VELOCnY = 15 2 - EXPECTED PROPORTION BYPASSED
» DIFFERENCES BETBEEN EXPECTED AND OBSERVED VALUES SIGNIFICANT AT «= 85 LEVEL
Figure B-6. Proportion of muskellunge bypassed by slot width (denoted in mm
above each bar) and screen orientation for each slot and bypass
velocity.
79
-------
BYPASS VaOCITY = 7 6 c»/sec
1.8
89
88
ge?
If)
L
H
I-
ra
o8
i
0
183
82
8.1
88
5 1
m
'///,
i
» »
I 2
Wi
w,
W4
w/
w/
V//ii
89 —
88 —
S87
H
h
"e
i
0
£83
82
6.1
W/
w/
'///,
2L_
76 152
SLOT VELOCITY (c./sec)
BYPASS vaxrn = SB 5 c./s
» tf w « »
5 1 * 5
I8r- rV^i-c
OT
i? r1!
« ft ft K
1251
Wl
w/
777
'/////
W/
'/////.
77
^
Vn
'///1
771
771
''/ I
'/>/ i
W/
VA
'/'/'/
'///,
w/
m
7,77
' //,
m
'///
W/!
76
152
SL8T VaOCITY (c»/sec)
i
7 ffl
7 7
7 7
7 7
7 '/
7 7
7 7
/ 7
m
Wi
R//I 2
1771
n 9
5 I
'M
'H
77
Wn
M
w/
m
I/'/',
W/
'////
'/ /',
I III
'////
m
229
PROPORTION BYPASSED
t-> J» cn e» — i
82 —
0
1
0
183
V
V
.*'
X
s* r
1
1
76
» < « « »
51251
B
!
B
2
\
(PASS
X
SL
1PASS
aocr
* *
5 1
FY
*
1
5*
2
!
152
OT VELOCITY (cm
VELOCITY = 61 c
* * I i
5 1 f 5 1
Cl
1
/M
«/»
2
SK
N
e)
ec
K
i
5*
i
////
77
77
77
77,
/ /
77,
77
V1/
77
V/,
229
ft ft X ft
5 1 * 5 1
76 15 2 22 9
SLOT VELOCITY (en/sec)
|J - VERTICAL ^ - HORIZONTAL > - EXPECTED PROPORTION BYPASSED
•'^Denotes differences between expected and observed values significant at a = 0.05,
Figure B-7. Proportion of walleye bypassed by slot width (denoted in mm above
each bar) and screen orientation for each slot and bypass velocity.
80
-------
BYPASS VELOCITY = 15 2 a/sec
1.8
8.9
8.8
S8.7
in
10
18.6
ID
§8.5
H
1-
a
0
82
8.1
a ft
X W X
— Ill
* * *
1 1 1
- y
-
—
1 £ 1
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I
' /
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i
J^
]
///
\
if
V,
i
'/,
7.6 15.2 229
SLOT VaOCITY (a/sec)
BYPASS VaOCITY = 38 5 M/SK
BYPASS VELXITY = 61 ci/sec
1 8
8.9
8.8
S8.7
in
in
18.6
o
g8.5
H
g8.4
1
a
^83
82
8.1
88
-
nn
\
/
» *
I ?
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I
X
t
X
I
1
1 2 1
N
X
1
N,
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K
I
2*
1
/
1*
tt
I
1
76 152 229 "'" 7.6 152 22.9
SLOT VELOCITY Cci/sec) SLOT VaOCITY fa/sec)
[] - VERTICAL ^ - HORIZONTAL >
''•Denotes differences between observed and
- EXPECTED PROPORTION BYPASSED
expected values significant at a = 0.05.
Figure B-8. Proportion of smallmouth bass bypassed by slot width (denoted in
mm above each bar) and screen orientation for each slot and bypass
velocity.
81
-------
ions
CD
<\i
in
(
z
o
ZH
CO Ol-
CO H< 1
< t-l- t
03
1
i
/•
(
f
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m g
SJ iii
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to
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LD
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i i
-------
CHANNEL CATFISH
1.0-
0.8-
0.6-
0.4-
0.2-
-0.4-
-0.6-
-0.8-
1.0-
% 0.8-
^ 0.6-
m 0-4-
uj 0-2-
5-?-2-
-0.6-
-0.8-
1.0-
0.8-
0.6-
0,
0.
4
2
-0.2-
-0.4-
-0.6-
-0.8-
O VERTICAL ORIENTATION
• HORIZONTAL ORIENTATION
O
15.2
H
Ld
_J
OT
7.6
I I
7.6 15.2
!
30.5
BYPASS VELOCITY Ccm/^ec)
61 .0
Figure B-10.
Results of larval fish screening investigations ("fish avoidance"
concept): relationship of relative bypass to bypass and slot
velocity for channel catfish. Slot width of screen - 2.0 mm.
83
-------
STRIPED BASS
O VERTICAL ORIENTATION
HORIZONTAL ORIENTATION
1 .0-
0£±
.8-
0.6-
0.4-
0.2-
0O(—
1@
-0.2-
-0.4-
-0.6-
-0.8-
1 .0-
0.8-
0.6-
0.4-
0.2-
0d_
V
-0^2-
-0!s-
1 .0-
0.8-
0.6-
0.4-
0.2-
0rti
W"~
-0!2-
-0.4-
-0.6-
-0.8-
m
•^ * o
o- — o—
^^^^^ _^
OL...O^-''" *""
•>— =fl*^— — •
*"^""^ r — ~~ g~~ — *"*
O ^0
III 1
7.6 15.2 30.5 61 .0
22.9
15.2
o
-------
STRIPED BASS
O VERTICAL ORIENTATION
HORIZONTAL ORIENTATION
1 .0-
0.8-
0.6-
0.4-
0.2-
0ft —
|£J
-0.2-
-0.4-
-0.6-
-0.8-
1 .0-
-------
STRIPED BASS
0.8-1
0^4-
8.2-
0.0-
-0.2-
-0.4-
-0.6-
-8.8-
I .0-
0.8-
0.6-
0^2-
f-j -0.4-
a -0.6-
1 .0-
0.8-
0.6-
0.4-
0.2-
0. 0-
-0.2-
-0.4-
-0.6-
-8.8-
VERTICAL ORIENTATION
HORIZONTAL ORIENTATION
22.9
O
O
W
\
E
O
15.2 8
ui
7.6
\ I I
7.6 15.2 30.5
BYPASS VELOCITY (cm/sec)
61 .0
Figure B-13.
Results of larval fish screening investigations ("fish avoidance"
concept): relationship of relative bypass to bypass and slot
velocity for striped bass. Slot width of the screen = 2.0 mm.
Test 1.
86
-------
STRIPED BASS
1.0-
0.8-
0.6-
0.4-
0.2-
0.0-
-0.2-
-0.4-
-0.6-
-0.8-
1.0-
0.8-
0.6-
0.4-
0.2-
0.0-
-0.2-
-0.4-
-0.6-
-0.8-
1.0-
0.8-
0.6-
0. 4-
0
0
-0
-0.4
-0.6
-0.8
2-
-0.2-
O VERTICAL ORIENTATION
• HORIZONTAL ORIENTATION
O
22.9
o. .......
15.2
O
0)
O
I—
M
O
O
UJ
o —
—
7.6
7.6 15.2 30.5
BYPASS VELOCITY Ccm/sec)
61 .0
Figure B-14.
Results of larval fish screening investigations ("fish avoidance"
concept): relationship of relative bypass to bypass and slot
velocity for striped bass. Slot width of the screen = 1.0 mm.
Test 2.
87
-------
STRIPED BASS
1 .0-
0.8-
0.6-
0.4-
0.2-
0.0
-0.2H
-0.4
-0.6-
-0.8-
<
Q.
U
1.0-
0.8-
0.6-
0.4-
0.2-
t -0 • 2-
•*c ^
-0.6-
-0.8-
1.0-
0.8-
0.6-
0.4-
0
0.0
-0.2
-0.4
-0.6
-0.8
2-
O VERTICAL ORIENTATION
• HORIZONTAL ORIENTATION
22.9
15.2
u
9
O
O
O
_J
UJ
O
_J
V)
7.6
7.6 15.2 30.5
BYPASS VELOCITY Ccm/sec)
61 .0
Figure B-15.
Results of larval fish screening investigations ("fish avoidance"
concept): relationship of relative bypass to bypass and slot
velocity for striped bass. Slot width of the screen = 2.0 mm.
Test 2.
88
-------
WALLEYE
LU
O VERTICAL ORIENTATION
HORIZONTAL ORIENTATION
1 0-
0.8-
0.6-
0.4-
0.2-
-0.2-
-0.4-
-0.6-
-0.8-
1 0
0.8-
0.6-
0.4-
0.2-
-0.2-
-0.4-
-0.6-
-0.8-
1 0-
0.8-
0.6-
0.4-
0.2-
„ \Q '
-0.2-
-0.4-
-0.6-
-0.8-
^ ^^ Q
*
22.9
15.2
U
«
0)
U
M
O
O
_l
UJ
O
_J
CO
7.6
I
7.6 15.2 30.5
BYPASS VELOCITY Ccm/sec)
61 .0
Figure B-16.
Results of larval fish screening investigations ("fish avoidance"
concept): relationship of relative bypass to bypass and slot
velocity for walleye. Slot width of the screen = 0.5 nun.
89
-------
WALLEYE
CO
1.0-
8,8=
8,6-
0^4-
0,2-
0 . 0-
0.8
»8-
£ 0.6=
fc 0.4-
i- -0 2-
•< °
a -0.6-
-0.8-
1 .0=
0,8^
0.6-
0.4-
0,2=
0.0-
-0,2-
-01e-
-0.8-
O VERTICAL ORIENTATION
• HORIZONTAL ORIENTATION
22.9
•9
15.2
O
-------
WALLEYE
O VERTICAL ORIENTATION
HORIZONTAL ORIENTATION
1 .0-
0.8-
0.6-
0.4-
0.2-
0m
. 0-
-0.2-
-0.4-
-0.6-
-0.8-
1 .0-
% 0.8-
^ 0.6-
^ 0.4-
uj 0.2-
S ~0-2~
jJ-0.4-
o: -0 . 6-^
-0.8-
1 .0-
0.8-
0.6-
0.4-
0.2-
0n>
. 0—
-0.2-
-0.4-
-0.6-
-0.8-
- „„ O
,^-°-
^^ ^, ^
^^x" 0 •• ' "" a~3"**"
•
O 0
O- 0-^ • — w
^^•^^
^O ^«.»Q ™""8
O^^^. „.,.„. 9
22,9
15
u
«
(0
X
M
O
o
i r
7.6 15.2 30.5
BYPASS VELOCITY Ccm/sec)
61 .0
Figure B-18.
Results of larval fish screening investigations ("fish avoidance"
concept): relationship of relative bypass to bypass and slot
velocity for walleye. Slot width of the screen = 2.0 mm.
91
-------
SMALLMOUTH BASS
OVERTICAL ORIENTATION
1 0-
0.8-
0.6-
0.4-
0.2-
00-
-0.2-
-0.4-
-0.6-
-0.8-
1 .0-
£ 0.8-
£ 0.6-
^5 0.4-
u 0.2-
> a Q_
H * .V
5-0.2-
^"2-i"
Qi -0.6-
-0.8-
1 .0-
0.8-
0.6-
0.4-
0.2-
0Q —
. >u
-0.2-
-0.4-
-0.6-
-0.8-
-^----0 o
g o n
8^^
22.9
15.2
O
o
M
O
O
_J
UJ
o
_J
to
7.6
I
7.6 15.2 30.5
BYPASS VELOCITY Ccm/sec)
61 .0
Figure B-19.
Results of larval fish screening investigations ("fish avoidance"
concept): relationship of relative bypass to bypass and slot
velocity for smallmouth bass. Slot width of the screen = 1.0 mm.
92
-------
SMALLMOUTH BASS
O VERTICAL ORIENTATION
HORIZONTAL ORIENTATION
1 .0-
0.8-
0.6-
0A
. 4—
0.2-
0o
. id
-0.2-
-0.4-
-0.6-
-0.8-
1 .0-
8 0.8-
^ 0.6-
^ 0.4-
uj 0-2-
> o r>
j^ y . 0—
^-0.2-
-0!s-
1 .0-
0.8-
0.6-
0.4-
0.2-
001—
. w
-0.2-
-0.4-
-0.6-
-0.8-
Q O
n'~~'~ m »
^^^**"^
^B ^^^
—
o*"""" • >—-*
^^^"^
^^^^^
"^^
_Q__-_ Q
^~~S* *
^^^
^s^
22.9
15.2
U
O
(0
\
£
O
O
O
UJ
o
CO
7.6
7.6 15.2 30.5
BYPASS VELOCITY Ccm/secD
61 .0
Figure B-20.
Results of larval fish screening investigations ("fish avoidance"
concept): relationship of relative bypass to bypass and slot
velocity for smallmouth bass. Slot width of the screen =2.0 mm.
93
-------
APPENDIX C
FORMULA FOR ADJUSTING IMPINGE-RELEASE TEST RESULTS
BASED ON CONTROL SURVIVAL
94
-------
APPENDIX C
FORMULA FOR ADJUSTING IMPINGE-RELEASE TEST RESULTS
BASED ON CONTROL SURVIVAL
Individual 24-hour survival values were adjusted for observed mortality of
the control fish in order to better reflect test-induced mortality. The adjusted
values were calculated using the formula:
Adjusted survival =
1 - [(D/N) - Mc)]
where
D = the total number of fish in a sample which died.
N = total number of fish in the sample.
M = average control mortality (expressed as a proportion).
For example, assume that for one observation with species A:
N = 200 specimens
D = 160 specimens
M = .45
c
Unadjusted survival =
D _ ,160
1 N " l 200 " -2°
Adjusted survival =
1 - [(160/200) - M ] = 1 - [.80 - .45] = .65
These values were expressed as a percent in this report.
95
-------
APPENDIX D
ANALYSIS OF VARIANCE FOR FOUR
SPECIES SUBJECTED TO IMPINGEMENT,
AIR EXPOSURE, AND SPILLING
96
-------
TABLE D-l.
APPENDIX D
ANALYSIS OF VARIANCE FOR FOUR
SPECIES SUBJECTED TO IMPINGEMENT,
AIR EXPOSURE, AND SPILLING
ANALYSIS OF VARIANCE OF IMPINGEMENT, AIR EXPOSURE, AND
SPILLING FOR REDBREAST SUNFISH. ANALYSIS IS BASED ON
INITIAL SURVIVAL.
Source
Model
Error
Impingement
Air Exposure
Spill
Imp. Dur. x Air Exp.
Imp. Dur. x Spill
Air Exp. x Spill
Corrected Total
df
8
21
2
1
1
1
2
1
29
Sum of
Squares
6.43704
0.56394
4.76797
0.10162
0.03770
0.01258
0.04331
0.02482
7.00098
F-value
29.96
88.77
3.78
1.40
0.47
0.81
0.92
Pr > F
0.0001
0.0001
0.0652
0.2493
0.5012
0.4598
0.3473
R- square
0.91945
TABLE D-2. ANALYSIS OF VARIANCE OF IMPINGEMENT, AIR EXPOSURE, AND
SPILLING FOR REDBREAST SUNFISH. ANALYSIS IS BASED ON
ADJUSTED 24-HOUR SURVIVAL.
Source
Model
Error
Impingement
Air Exposure
Spill
Imp. Dur. x Air Exp.
Imp. Dur. x Spill
Air Exp. x Spill
Corrected Total
df
8
21
2
1
1
1
2
1
29
Sum of
Squares
4.67616
0.36138
3.42956
0.09723
0.04341
0.05132
0.04617
0.06590
5.03754
F-value
33.97
99.65
5.65
2.52
2.98
1.34
3.83
Pr > F
0.0001
0.0001
0.0270
0.1271
0.0989
0.2830
0.0638
R- square
0.92826
97
-------
TABLE D-3. ANALYSIS OF VARIANCE OF IMPINGEMENT, AIR EXPOSURE, AND
SPILLING FOR LARGEMOUTH BASS. ANALYSIS IS BASED ON
INITIAL SURVIVAL.
Source
Model
Error
Impingement
Air Exposure
Spill
Imp. Dur. x Air Exp.
Imp. Dur. x Spill
Air Exp. x Spill
Corrected Total
df
9
26
2
1
1
2
2
1
35
Sum of
Squares
1.69428
0.61991
0.72110
0.64616
0.00067
0.18027
0.13884
0.00725
2.31419
F-value
7.90
15.12
27.10
0.03
3.78
2.91
0.30
Pr > F
0.0001
0.0001
0.0001
0.8685
0.0362
0.0723
0.5862
R- square
0.73213
TABLE D-4. ANALYSIS OF VARIANCE OF IMPINGEMENT, AIR EXPOSURE, AND
SPILLING FOR LARGEMOUTH BASS. ANALYSIS IS BASED ON
ADJUSTED 24-HOUR SURVIVAL.
Source
Model
Error
Impingement
Air Exposure
Spill
Imp. Dur. x Air Exp.
Imp. Dur. x Spill
Air Exp. x Spill
Corrected Total
df
9
26
2
1
1
2
2
1
35
Sum of
Squares
2.13859
0.94435
1.22243
0.64087
0.00924
0.07878
0.18461
0.00167
3.08295
F-value
6.54
16.84
17.64
0.25
1.08
2.54
0.05
Pr > F
0.0001
0.0001
0.0003
0.6183
0.3529
0.0982
0.8320
R- square
0.69369
98
-------
TABLE D-5. ANALYSIS OF VARIANCE OF IMPINGEMENT, AIR EXPOSURE, AND
SPILLING FOR BIGMOUTH BUFFALO. ANALYSIS IS BASED ON
INITIAL SURVIVAL
Source
Model
Error
Impingement
Air Exposure
Spill
Imp. Dur. x Air Exp.
Imp. Dur. x Spill
Air Exp. x Spill
Corrected Total
df
6
17
1
1
1
1
1
1
23
Sum of
Squares
2.27082
0.16884
1.78999
0.23622
0.03469
0.20950
0.00015
0.00025
2.43966
F-value
38.11
180.23
23.78
3.49
21.09
0.02
0.02
Pr > F
0.0001
0.0001
0.0001
0.0790
0.0003
0.9008
0.8763
R-square
0.93079
TABLE D-6. ANALYSIS OF VARIANCE OF IMPINGEMENT, AIR EXPOSURE, AND
SPILLING FOR BIGMOUTH BUFFALO. ANALYSIS IS BASED ON
ADJUSTED 24-HOUR SURVIVAL.
Source
Model
Error
Impingement
Air Exposure
Spill
Imp. Dur. x Air Exp.
Imp. Dur. x Spill
Air Exp. x Spill
Corrected Total
df
6
17
1
1
1
1
1
1
23
Sum of
Squares
2.50655
0.83484
2.06539
0.02346
0.00469
0.09768
0.25786
0.05747
3.34140
F-value
8.51
42.06
0.48
0.10
1.99
5.25
1.17
Pr > F
0.0002
0.0001
0.4987
0.7610
0.1765
0.0350
0.2945
R-square
0.75015
99
-------
TABLE D-7. ANALYSIS OF VARIANCE OF IMPINGEMENT, AIR EXPOSURE, AND
SPILLING FOR WALLEYE. ANALYSIS IS BASED ON INITIAL
SURVIVAL.
Source
Model
Error
Impingement
Air Exposure
Spill
Imp. Dur. x Air Exp.
Imp. Dur. x Spill
Air Exp. x Spill
Corrected Total
df
9
47
2
1
1
2
2
1
91
Sum of
Squares
0.97298
4.74461
0.93306
0.00130
0.00004
0.01621
0.00904
0.00047
5.71759
F-value
1.07
4.62
0.01
0.00
0.08
0.04
0.00
Pr > F
0.4014
0.0147
0.9102
0.9837
0.9230
0.9563
0.9454
R- square
0.17017
TABLE D-8. ANALYSIS OF VARIANCE OF IMPINGEMENT, AIR EXPOSURE, AND
SPILLING FOR WALLEYE. ANALYSIS IS BASED ON ADJUSTED
24-HOUR SURVIVAL.
Source
Model
Error
Impingement
Air Exposure
Spill
Imp. Dur. x Air Exp.
Imp. Dur. x Spill
Air Exp. x Spill
Corrected Total
df
9
47
2
1
1
2
2
1
56
Sum of
Squares
2.42175
2.74357
0.65694
1.07269
0.11618
0.46774
0.05809
0.05549
5.16532
F-value
2.15
6.51
3.28
0.49
0.53
0.05
0.84
Pr > F
0.0341
0.0024
0.0736
0.4852
0.5903
0.9484
0.3615
R- square
0.19086
100
-------
REFERENCES
Ostle, B. 1963. Statistics in Research. The Iowa State University Press, Ames,
Iowa. 585 pp.
101
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 REPORT NO.
EPA-600/7-80-094
3. RECIPIENT'S ACCESSION NO.
4. TITLE ANDSUBTITLE
Evaluation of Two Concepts for Protection of Fish
Larvae at Cooling Water Intakes
5. REPORT DATE
May 1980
6. PERFORMING ORGANIZATION CODE
7 AUTHORIS)*D. A. Tomljanovich,*J. H. Heuer J. B. Brel-
lenthin, J. T. Johnson,S. H. Magliente, *M. Smith,
*P. Smith, *S_. Vigander, and *R. Whittaker
8. PERFORMING ORGANIZATION REPORT NO.
TVA EDT-102
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Tennessee Valley Authority
Division of Energy Demonstrations and Technology
Chattanooga, Tennessee 37401
10. PROGRAM ELEMENT NO.
ME624A
11. CONTRACT/GRANT NO.
EPA Interagency Agreement
D8-O721-BE
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; 5/75-3/80
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES IERL-RTP project officer: Theodore G. Brna, MD-61, 919/541-
2683. TVA project director: H. B. Flora II. (*) Coauthors are with TVA, Office of
Natural Resources, Norris, TN 37828.
16. ABSTRACT
repOr|- gjves results of a laboratory evaluation of 'impinge -release' and
'fish-avoidance' concepts for protecting fish larvae at cooling water intakes.
Impinge-release requires a vertical-traveling screen that limits impingement time
to several minutes , the maximum time depending on the species to be protected. A
stationary slotted screen in flowing water was used to evaluate the ability of fish to
avoid entrapment. Both concepts showed high potential for protecting larvae as well
as older life stages. Approach velocities = or < 30. 5 cm/s did not affect survival.
But at 61 cm/s, survival was usually significantly reduced, especially for impinge-
ments over 2 minutes. Fish in a water-holding tray of a screen panel had higher
survival than fish exposed to air on emergence of the panel from water. Low pres-
sure sprays for rinsing fish into and from the tray, followed by spilling the fish into
a return trough, did not significantly reduce survival. The large range in swimming
ability, size, and behavior among species gave large differences in their avoidance
response. Adequate protection for small larvae may require 0. 5-mm slots and
through-screen (slot) velocity = or < 7. 5 cm/s. Large larvae (> 10 mm) can avoid
screens with 2-mm slots and a 7. 5-cm/s slot velocity. Except for channel catfish,
larvae avoidance of the slotted screen was higher during daylight.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
COS AT I Field/Group
Pollution
Fishes
Larvae
Cooling Water
Water Intakes
Impingement
Releasing
Avoidance Responses
Pollution Control
Stationary Sources
Impinge-release
Fish-avoidance
13B
06C,08A
ISA
13M
14B
05J
13. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
112
20. SECURITY CLASS (This page}
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
102
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