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# -- and Electric PowerGeneration,no.1 

# Impactsof 

# PowerPlant

# Intake Velocities

# onFish

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# FishandWildlife

# Service US.Departmentof

# theInteriorFWS/OBS-76/20.1 March 1977

Topical Briefs: Fish and Wildlife Resources and Electric Power Generation, no. 

### 1



## IMPACTS OF 

## POWER PLANT INTAKEVELOCITIES ON FISH

John Boreman National Power Plant Team 1451 Green Road Ann Arbor, Michigan 

### 48105

Power Plant Project Office of Biological Services Fish and Wildlife Service U.S. Department of the InteriorPreface
The series Topical Briefs: Fish and Wildlife Resources and Electric Power Generation is published by the National Power Plant Team of the Power Plant Project to provide a set of concise summaries on topics related to electric power generation and transmission and their effects on fish and wildlife resources. The briefs are written for fish and wildlife biologists who review and make recommendations regarding electric power projects. Each brief contains background information on and a discussion of the particular topic, a selected bibliography of additional information sources, and, in some cases, a strategy to address the problem. Any suggestions or questions regarding Topical Briefs should be directed to: Information Transfer Specialist National Power Plant Team 1451Green Road Ann Arbor, Michigan 48105 (313) 994-3331 ext. 238 PTS: 378-1238

# IMPACTSOF 

# POWER PLANT INTAKEVELOCITIES ON 

# FISH

Abstract This report outlines biological problems associated with power plant intake velocities. Informationneeded to assess impacts of intake velocities on fishery resources and a list of technical references containing more detailed analyses 

### of the problems and mitigation alternatives are included.
INTRODUCTION
There is growing recognition that mortality of aquatic biota due to entrainment or impingement at power plant intakes produce substantial impacts on estuarine, riverine, lacustrine, and coastal ecosystems. 

### In some power plants water withdrawal 

### may produce greater losses to fishery resources than thermal pollution. For example, up to 

### 165.5 million menhaden larvae were killed per day by entrainment at the Brayton Point Plant in Massachusetts during the summer 

### of 1971 (U.S. Environmental ProtectionAgency 1972). The ecological implications 

### of this mortality are not yet known.

L R PLANT 

# 1 ENTRAINMENT EVENT

Brayton Point, 7.0 to 165.5 million menhaden Mt. HoDe Bay. Mass. (some river herring) killed 

# I .. per day

50 million fishkilled in 11 days

Hillstone, 36 million fishkilled in Niantic Bay, Conn. 16 days (probably menhaden blueback herring) 

# I 2.5 million flounder entrained

Connecticut Yankee, Conn. River, Conn 179 million fish larvae killed per year 1 I

Indian Point, Predicted 7.3 million Audson Estuary, N.P. striped bass killed per year, larvae and juveniles Seabrook, Predictedkillof 74 million Hampton-Seabrook clam larvae per day Estuary, N.H. DATE COMMENT -~ Summer. L371 Estimated from EPA's sampling techniques. 164.5 million kill on July 2; fishmangled. August 10-21, Estimated from net tons 1971

Nov. 2-18, 1971
Apr.-June 1972

196961970

Future

Future at discharge; menhaden and blueback herring; tests showed all fish died.

Estimated by sampling of vertebrae of dean fish in discharge channel. Death rate not estimated

Estimated by B. Marcy. 

# I

For Units 162; estimated Prom estuary sampling in 1966 and 1967.
Estimatefor.proposed plant; 74 million is initialkill at plant startup, lower rate after equilibrium reached.
Table 

### 1. Reports and Predictions of Power Plant Entrainment (U.S. 'EnvironmentalProtectionAgenc:y 1976a)



### 1

# I 2 Intake Velocities

WER PLANT IMPINGEMENT EVENT I /Millstone, Niantic Ba? Massive kill of small menhaden (more than 2.0 million), screens clogged.



### . H. Robinson, 7,191,785 fish impinged inone year. lalvestonBay, Tex. 

# I Indian Point, No. 1 Yearly kill of 1.0 to 1.5 million fish.
udson River, N.Y. Killof 1.3 million in 9 112weeks 

# 1

ndian Point, No. 2 Massive kills; maximum per day 120,000

175,003 fish killed in 5 days.

ndian Point. No. 1.2 Predicted totalkill 6.5 million fish p
ort Jefferson 2 truckloads (at least) of fishkilled on screens in 3 days. 

# I rystal River Predicted annual kill of 400,000 fish and 100,000 shellfish. 

### I brayton Point 350,000 fishinpinged in one year; mostly menhaden yster. Creek, 10,000 fish, 5,000 crabs, destroyed pel arnegat Bay, N.J. month in spring and summer.

urry Power Station 6 million river herring destroyed in 2-3 monrhs DATE

1971

1969-70

1965-72
1969-70

Jan. 71

Feb. 72

:year Jan. 26-28 1966 1969

1971-TZ

1971

Oct.-Dec. 1972 COMMENT
Occurring late summer, early fall; plant shut down on 8121i71; persistent low killof 10 other species. Projected from sampling of operating plant; principal species were menhaden, anchovy, croaker; highest in ?larch. Primarily white perch with 4-10% srriped bass. 10% striped bass; plant closed Feb. 8. Testing cooling system of new plant (no heat); white perch 6 other species Testing again (no heat) Con. Ed. fined $1.6 million by N.Y. forkills. With both ulants in full overation Mostly sinail menhaden; alsowhite perch.
Based upon operation of 3 units (2 units now destroy 1.2 this amount).
Heaviest from Nov-March; flounder, silverside, 6 other also impinged.
Estimated from 19 days of sampling; screen kill incold season unknown.
Estimated by AEC from screen samplings during partial power runs.
Power Plant Impingement

STATEMENT 

### OF THE PROBLEM
Rates of entrainment and impingement of aquatic resources are directly related to intake velocities at and around the intake structures, and also to numerous other physical and biological phenomena. An understanding of these phenomena is necessary to make effective recommendations concerning intake velocities. Hydrodynamic conditions in the water body are the principal physical phenomena controlling entrainment and impingement. Three types of hydrodynamic conditionsmay exist (with associated site-specific modifications): a stagnant pool system, such as a lake or pond with no prevailing currents; an uni-directional system, such as a stream, river, or coastal systemwith one prevailing current in the vicinity of the intake; and a multi-directional flow system, such as in an estuary.Intake Velocities 3

Relative location and construction details 

### of the intake structure are also important,because they control flow conditions in the immediate vicinity 

### of the intake. The location of the structure in relation to the shoreline, bottom, and water surface influences the abundance, variety, and extent of withdrawal of aquatic organisms. Construction of skimmer wall%, submergedweirs, velocity caps, etc., can limit the zone of power plant water withdrawal, and screens set at an angle to the direction of inflowmay reduce the impingement 

### of small fish considerably (Stone & Webster Engineering Corporation 

### 1976).

IdealizedVelocitj/ Distributi0n [dealized Velocity Distribution Without Cap With Cap

Figure 

### 1. Operation of the Velocity cap 

### (U.S. Environmental ProtectionAgency 1976a)

Biological phenomena that influence the magnitude of entrainment and impingement of aquatic organisms include their: 

### (1) motility; (2) physiological and behavioral responses to factors such as temperature, salinity, oxygen concentration, currents, etc.; (3) vertical and horizontal distribution 

### in the vicinity 

### of the power plant intake; and (4) growth rate which governs the period 

### of vulnerability to entrainment or impingement during each life stage.
The biologist should be aware of the following problems inherent in discussions of entrainment and impingement impacts on critical fishery resources that appear in environmental reports, environmental impact statements, 316(b) demonstrations and other such reports. The biologist should also conskder the design stage.

# I 4. Intake Velocities

method has yet been established for predicting the zone of influence on aquatic organisms around power plant intake. Three-dimensional velocity profile models superimposed on movement patterns of aquatic species are one approach to this problem. However, these models are still in the formulative stage. Simplisticmathematical models neglect important hydrodynamic phenomena necessary for predicting 

### flow conditions in the studies do not reflect the reaction 

### of aquatic organisms to the higher velocities in the immediate vicinity of intakes and. therefore. are
Relating swimming speeds of fishes to intake vulnerability. 

### Impingement and entrainment rates 

### of fishes are dependent on much more than simply their ability to maintain position in a given velocity for a given period of time. For example, available data indicates that 

### impingement rates of fishes are strongly influenced by temperature and salinity conditions in the vicinities of estuarine power plant intakes. Rheotaxis (response of 

### an organism to current), phototaxis (response to light), and tactile responses also are important in determining the Vulnerability 

### of a species. Furthermore, fish may hold a position inmediately in front of the intake structure and become susceptible to entrainment or impingement upon exhaustion. Reports may also mention an organism's capacity to exert a burst of speed to support arguments for reduced vulnerability to intakes. However, such arguments are seldom supportablebecause initial orientation, distance and direction travelled, and the types 

### of stimuli that elicit a sudden burst 

### of speed all are variables that can not be sufficiently documented.
Meamirernents of intake velorities. The rennrt shnnlrl crate t-yartlv where measurements or estimates of intake velocities have been made with respect to the intake structure,water surface and bottom, tide, river sitage, and other pertinent variables. Often an average intake velocity is reportedwith no indication 

### of the range of velocities across the intake structure; some parts of the intakemay have close to zero velocity,while others may have velocities much higher than the "average". Furthermore, 

### low velocities are extremely difficult to measure, and the accuracy of 

### these measurements may be auestisonable.



### i 

# I IIntake Velocities 5

0061 

### 0.08E

I



### 007: 

# t

NOTES:

1. VELOCITIES SHOWNINMETERS/ SEC 2-MEANREMENTSMADE BETWEEN DEICING LOCP PIPEAND BAR RACKS INMARCH 1370 3.ME4WRFMENTS MADEAT A WATER FlDW RATE 60'1. OF NU CAPABILITY Figure 2. Undesirable Intake Well Velocity Profiles 

### (U.S. Environmental ProtectionAgency 1976a)

Stagnant pool areas around the intake. All intakes are designed to prevent the pumps from running dry. 

### To keep them from running dry some companies construct a reservoir. 

### In such cases, a stagnantwater area usually occurs in the vicinity of intakes,which allows material such as sand and silt to settle out and concentrations 

### of aquatic organisms to increase. Vulnerability of the aquatic organisms to the intakes is also increased. These areas can be created by breakwaters in combination with a dredged-out area, sheet pile walls, ponds dredged adjacent to the river, intake canals, etc. Relation 

### of intake location to plant discharge. Fish and shellfish often are attracted to the discharge, and more of themmay be subjected to entrainment or impingement if the intake is located too near the discharge.SUGGESTED STRATEGY
Entrainment: Eggs and early larval stages of aquatic organisms are particularly vulnerable to entrainment. Volume of intake flow is often more important than intake velocity 

### in determining degree 

### of impact. 

### If important fishery resources are likely to be entrained at a power plant, the project report should include the following:

* Accurate delineation of vertical and horizontal distribution 

### of eggs and larvae by species in the expected zone of withdrawal. Informationon the period of vulnerability 

### of the resource to entrainment, including data 

### on duration of the egg and larval stages, length of spawning season, and relationship 

### of developmental periods to environmental factors (e.g., temperature) that are likely to affect them. Description of the physical and biological phenomena that could increase vulnerability,such as tidal cycles, current patterns, location 

### in intake, behavior, etc. Indication of .thevolume of water withdrawal in relation to the net flow 

### of the water body.



# - Estimates of the egg and larvae population sizes.



# - Evaluation 

### of significance of entrainment losses to recreational and commercial fisheries.
Reduction of entrainment losses can be accomplished by several methods, including use of skimmer walls, velocity caps, and submerged weirs to control the zone of withdrawal; relocation of the intake in areas of less critical habitat; 

### or construction of a closed-cycle cooXing system to reduce the volume 

### of water withdrawal. Seasonalmode operation of once-through cooling during periods 

### of 

### low potential impact may also be recommended. 

### It cannot be overemphasized that the

## best way to minimize the impact 

### of a power plant 

### on important aquatic resources is t:o site the plaat in a locationwhere such resources are very scarce.

aIntake Velocities 7

Impingement. Juvenile (post-larval) stages of fish are much more vulnerable to impingement losses than any other life stage. In some instances, however, substantial impingement of adult fish can occur. If critical fishery resaurces are likely to be impinged at power plant intakes, the project report should contain the following:



# - Accurate delineationmovement patterns of the critical fishery resource through the zone of withdrawal. Description of the physical and biological phenomena that may increase the vulnerability 

### of a species to impingement, such as temperature, salinity, currents,behavior, etc. 

### If fishby-pass systems are utilized, evidence that fish returned to the water body will survive, grow, and reproduce successfully.



# - Estimation of the numbers and sizes of impinged species in relation to the quantity of wa.terpassing through the plant, intake current velocities, season,water temperatures, stage of tide, illumination,and other environmental conditions.

* Population estimates of the impingeable stocks of aquatic organisms. Evaluation of the degree to which impingement losses will reduce recreational and comercial fisheries.
Reduction 

### of impingement can be accomplished by use of methods such as travelling screens, fishbypass systems, louvers, relocation of the intake, etc. Air bubbler screens and sound waves have not been shown to be effective measures.
More detailed analyses of alternate intakes that will reduce entrainment and impingement are found in the Atomic Industrial Forum source book on cooling water intakes (Battelle 1975) and the U.S. Environmental ProtectionAgency's cooling water intake development document (1976a). Guidelines for studies related to power plant intake velocity impacts on aquatic resources are presented in the 

### U.S. Environmental Protection Agency's 316(b) technical guidance manual (19762)).


### It is important to keep in mind that closed-cycle cooling is not the best available technology in all cases. Minor alterations in existing open-cycle systems to minimize impact should be recommended whenever possible. Each systemmust be judged on a case-by-case basis.CURRENT POLICY
The U.S. Environmental Protection Agency (1973) recommends reducing intake velocities to below 

### 0.5 ft/sec(fps) at the trash rack to enable fish to escape the screenwell. The U.S. Nuclear Regulatory Commission (1975) recommends that "...the site should have characteristics that allow placement of intake structureswhere the relative abundance of impbrtant species is small and where 

### low approach velocities can be attained." Also "...approach velocity and screen face velocity are the p.rincipa1design criteria for controlling the impingement of larger organisms, principally fish, on intake screens. Acceptable approach and screen face velocities are based on fish swim speeds which will thus vary with the species, site and season. Maximum acceptable approach velocities are on the order of 

### 0.5 fps." Fish and Wildlife Service concerns on intake velocities appeared in 

### Dr. Willis King's Instructional Memorandum RB-44, dated February 

### 5, 1973, and in the Navigable Waters Handbook 

### (U.S. Fish and Wildlife Service 1974). The memorandum reads: "The maximum velocity protecting most 

### small fish is 

### 0.5 fps but even lower velocities will entrain larvae and plankton and even 

### small fishwhere intake channels are not provided with an effective escape bypass."IntakeVelocities 9

REFERENCES CITED

Battelle. 1975. Environmental impact monitoring of nuclear power plants 

## -- source book 

### of moxitoring methods. Atomic Industrial Forum, Inc.,New York. 2 vols.
Stone & Webster Engineering Corporation. 1976. Studies to alleviate fish entrapment at power plant cooling water intakes: final report. Boston, Mass. 

### 1vol.


### U.S. Environmental ProtectionAgency. 1972. Proceedings in the matter 

### of pollution 

### of Mount Hope Bay and its tributaries. Washington, D.C. 643 pp. 

### U.S. Environmental ProtectionAgency. 1973. Reviewing environmental impact statements

## - power plant cooling systems, engineering aspects. Environmental Protection Technology Series EPA-660f2-73-016. Corvallis, Oregon. 93 pp.
U.S. Environmental ProtectionAgency. 1976a. Development document for best technology available for the location design, constructiohand capacity of coolingwater intake structure for minimizing adverse environmental impact. EPA 440f1-76f015-a. Washington, D.C. 263 pp. U.S. Environmental ProtectionAgency. 1976b. Guidance for determining best technology available for the location, design, constructionand capacity of cooling water intake structures for minimizing adverse environmental impact. Section 316(b) 

### P. L. 92-500. (draft 2) Washington, D.C. 50 pp. U.S. Fish and Wildlife Service. 1974. Navigable waters handbook. Loose-leaf pub. n.p. U.S. Nuclear Regulatory Commission. 1975. Regulatory 

### guide 4.7. General site suitability criteria for nuclear power stations. Washington,D.C. 30 pp.