AN INVENTORY OF SELECTED 

I/ FISH SCREENS IN CALIFORNIPr 

t 

Brian D. Quelvog 

Bay-Delta Fishery Project 

4001 North Wilson Way 

Stockton, CA 95205 

AXTRACT 

Fish screens have been used to protect fishery resources in California since 

the turn of the century. This report lists most screened agricultural diversions in California by location, screen rype, and size of diversion, Also 

included is a history of fish screens in California and a brief evaluation 

of the major types presently in use. 

I/ Anadromous Fisheries Branch Administrative Report No, 81-5 Submitted 

September, 1981. 
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INTRODUCTION 

Fish screens have been helping to maintain fishery resources in California 

since the turn of the century. A fish screen is simply a device to permit 

the passage of water, but not fish, from a stream, river, or other body of 

water. Such diversions typically supply water for municipal, industrial, 

and agricultural uses, Agriculture accounts for approximately 80% of the 

water diversions in California. 

In 1977 and 1980, questionnaires were sent to the five inland regions of the 

Department of Fish and Game (DFG) requesting information on all fish screens 

which they either constructed or maintain. This report summarizes the information provided and includes similar information on fish screens operated by 

federal, state, and local agencies. Not included are screens located on the 

coast or those associated with industrial diversions such as power plants. 

Although this is not intended to be an exhaustive listing, it does represent 

the majority of screened agricultural diversions in California, Of the 91 

screens listed, most are in Siskiyou, Trinity, and Tehama counties. Nearly 

all of these screens were constructed to protect salmon and steelhead resources. 

HISTORY OF FISH SCMENS IN CALIFORNIA 

Screens to control the movement of fish were being built well before the turn 

of the century. Leitritz (1952a) mentions one screen used in New York in 

1865 to prevent fish from escaping a pond. 

Fish screen requirements in California were originally set forth in the 

Penal-Codein 1891. Prior to 1912, there had been little effort to imple- . 

ment these requirements; however, the Fish and Game Commission was becoming 

increasingly aware of the need for fish screens and in 1912 created a Department of Screens and Ladders under the Superintendent of-Hatcheries, Although 

only a staff of two were originally assigned to the new department, over 500 

‘ screens had been reported in operation by 1919 (CFG 1919). 

Screening diversions soon began to meet with strong resistance although 

installations continued over the next 8 years. Many of the early screens 

didn‘t operate satisfactorily (Wales 1948; Leitritz 1952a) and the diverters 

were responsible for all the costs of installation and maintenance, 

In 1927, financial responsibility for fish screens began shifting toward the 

Fish and Game Commission with the passage of Assembly Bill 448. This bill 

required that if the Commission approved a fish screen and it subsequently 

failed, the Commission would have to pay for installation of a second screen 

(CFG 1927). 

In 1932, the resistance to fish screens was brought before the court in 

People vs. Glenn-Colusa Irrigation District. In its decision, the court 

upheld the right of the Commission, but as a direct result, legislation was 
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passed the next year to require the Division of Fish and Game to pay half of 

the original installation costs for fish screens, By 1965, the Fish and Game 

Code had been amended again to make the Department responsible for all costs 

associated with diversions under 250 cubic feet per second (cfs), 

As a result of fiscal constraints during the last 20 years and resistance 

by the water diverters, the Department has not been able to expand the number of screens or even replace most of the existing installations which 

have eicher worn out or never functioned satisfactorily. Wales (1948) 

recorded 91 screens operating in Siskiyou, Trinity, and Shasta counties 

in 1947 and recommended 98 screens be put on the Klamath drainage alone, 

Currently, there are only 62 screens in these counties. 

In the face of these obstacles, the Department initiated studies in the late 

1940's and early 1950's to list and prioritize diversions in California. New 

screens would be built or old screens upgraded on the basis of their importance to the salmon and steelhead resources. Concurrently, there was a renewed emphasis on designing screens that were more effective, less expensive to build, and relatively maintenance free, 

Some early screens were merely a set of parallel bars and were essentially 

refinements of a "rack" or "grizzly" (Spencer 1928). Experiments with more 

exotic barriers such as electric screens had not been fruitful (CFG 1923). 

By 1928, the simple bars were being replaced by stationary sets of inclined 

parallel bars with self-cleaning mechanisms or self-propelled rotating drums, 

In 1947, studies revealed that screen mesh size should be reduced from 6 mm 

(1/4in.) by 76 mm (3 in.) to 3 mm (118 in.) by 38 mm (13; in,) and that a 

bypass from the screen back to the stream is absolutely essential (Wales 

19481, Three years later, Wales, Murphey, and Handley (1950) introduced 

the Nurphey Perforated Plate Fish Screen. This self-cleaning screen had 

holes of 4 mm (5132 in.) on 5 rn (7/32 in.) centers which continues to be 

a standard for fish screens for salmon in California. 

Leitritz (1952 a, b) described various types of fish barriers including the 

parallel bar screen, rotary drum, and Murphey screens., Since then, numerous 

modifications have been made to the basic screen designs, 

SCREEN TYPES 

It is beyond the scope of this paper to describe every screen which has been 

used in California, many of which are custom-made for specific situations. 

Y Burns (1966) and Kabef (1977) provide general information on fish screen types 

in California. The descriptions below are limited to those screens listed in 

the appendix. 

I. Sloping Perforated Plate Screen 

The sloping perforated plate screen is essentially a Murphey screen. 

Inclined from upstream to downstream (approximately 30 degl and 
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perpendicular to the stream flow, this screen is mechanically sound 

and an efficient barrier to fish if operated within strict limits of 

designed flow. However, at other than design flow, fish are impinged 

on the screen and it is also easily clogged by excessive trash and 

debris. Due to these limitations, this type of screen is generally 

used on only small diversions, 

11. Vertkaf Rotary Drum Screen 

This drum screen rotates in the vertical axis and is one of the most 

trouble-free screens available, It is capable of accormnodating,wide 

fluctuations in water level. Construction is relatively difficult, 

and seals around the drum are a habitual problem, 

111. Horizontal Rotary Drum Screen 

This drum screen rotates in the horizontal axis and is one of the best 

self-cleaning screens. As water cannot be allowed to flow over the 

top of the screens, it has water level restrictions and the seals 

around the drum are rarely fish proof. 

IV. Gabion Fish. Screen 

Gabion fish screens (Menchen 1975) are constructed from perforated plate, 

rolled into tubes, buried in the gravel of the stream bed, and held in 

place with gabions, Installation costs are low, the design is simple, 

there are no moving parts, and large areas of screen can be exposed to 

the flow in a small area of stream. Cleaning the screens may be a 

problem depending on water conditions (Jerome Staley, Fisheries Management Supervisor and Charles Young, Fish Habitat Supervisor 11, Calif. 

Dept. Fish and Game, pers. coma.>. 

V. Perforated' Pipe Screen 

These are simply perforated pipes placed on the bottom of the stream 

or protruding from the bank out into the flow. Severe problems with 

trash accumulation have limited the use of this type of screen (William 

Wilson, Fish Habitat Supervisor I, Calif. Dept, Fish and Game, pers. 

comm, 10 

VI, Vertical Diagonal Perforated Plate Screen 

Vertical diagonal perforated plate screens are set vertically in the 

channel and diagonally across the stream at an angle of less than 20 

deg with respect to the flow. Modifications for support structures 

have gradually reduced installation costs. These screens can be made 

"fish tight" and are relatively trouble-free, An inclined bar screen 
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is sometimes placed upstream to aid in trash removal. Either a system 

of oscillating wiper brushes (on screens less than 20 ft long) or 

brushes mounted on a single carriage (on screens more than 20 ft long) 

may be used for cleaning. 

VII, Sloping Diagonal Perforated Plate Screen 

These screens are similar to the vertical diagonal perforated plate 

screens with the single exception that the screen is sloped toward one 

side of the stream (approximately 60 deg with respect to the stream 

bottom). The sloping feature allows gravity and water flow to hold 

the screens in place and maintain proper tension on the wiper brushes, 

cutting construction and maintenance costs considerably.. 

VIIL. Louvers 

Similar louver systems are used at the U. S. Bureau of Reclamation, Tracy 

Fish Collecting Facility and the Department of Water Resources' John E. 

Skinner Delta Fish Protective Facility. Both utilize 320 ft of louvers spaced 1 in, apart and are arranged diagonally across the aqueduct 

intake channel, Each louver is aligned at 75 deg with respect to the 

flow. As water passes through the louvers, turbulence waves are created 

which fish will normally avoid, Fish guide in front of the louvers 

before entering a bypass which carries them to a second louver and 

bypass system. Fish are then directed into holding tanks prior to 

being transported by truck to sites near Antioch and released. Descriptions and evaluations of these facilities were accomplished by Bates, 

Logan, and Pesonen (1960) and Skinner (1974). These studies showed that 

successful salvage of fish depended on several factors including: fish 

species and size, approach and bypass velocities, and guiding structures. Subsequent studies have revealed fish losses due to predation 

and handling (Schaffter 1978; Hall 1980; Hallock in prep,). Although 

large facilities such as these are very costly to build and maintain, 

they provide a relatively inexpensive type of screening per volume of 

water diverted. 

I wish to thank John Riggs, Charles Young, Jr., Jerry Wise, William Wilson, 

Jerome Staley, and Robert Rawstron for providing the information on screens 

which was used in this report, Harold C. Cribbs was very helpful in researching codes pertaining to fish screens. I am also grateful to Alan Pickard and

Dan Odenweller �OK their editorial suggestions and Janet Boranian, Helen Hardy,

and Barbara Allen who typed the manuscripts. 
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REFERENCES 

Bates, D. W., 0. Logan, and E. A, Pesonen, 1960. Efficiency evaluation, 

Tracy Fish Collecting Facility, U, S. Fish and Wildlife Service and 

U, S. Bureau of Reclamation. 81 pp., 

Burns, J. W. 1966, Fish screens. . pp. 156-161. In: Alex Calhoun (ed.) 

Inland Fisheries Management. Calif. Dept, ofTish and Game, 

California Department of Fish and Game. 1919, Reply to the Eden Resolution by the executive officer of the Fish and Game Commission. Calif. 

Fish Game 5(4):184, 

1923. Hatchery Notes. Calif. Fish Game 9(4):165. 

1927. Summary of changes in Fish and Game laws. Calif. Fish Game 

13(3):190. 

1929. Self-cleaning fish screen. Calif. Fish Game 15(2):142-145. 

1933. Fish and Game legislation. Calif. Fish Game 19(4):268, 

California Department of Water Resources and Department of Fish and Game. 

1973. Evaluation testing program report �or Delta Fish Protective 

Facility, State Water Facilities, California Aqueduct, North San 

Joaquin Division, Memorandum Report. 211 pp. 

Hall, F. A. 1980. Evaluation of downstream migrant chinook salmon, Uncorhynchus tshawytscha, losses in Clifton Court Forebay, Contra Costa 

County, California, Calif. Dept. Fish and Game, Anad, Fish. Br. Admin. 

Rept. No. 80-4. 

Kabel, S. 1977. What's a fish screen? Outdoor California 38(3):6-7. 

Leitritz, E. 1952a, Stopping them: the development of fish screens in 

California. Calif, Fish Game 38(1):53-62, 

1952b. A new mechanical fish screen for hatchery ponds, 

Calif. Fish Game 38(3):405-406, 

Menchen, R, S, 1975, Perforated pipe used to screen and trap juvenile 

salmonids, Prog. Fish, Cult. 37(2):85-89. 

Schaffter, R. G. 1978, An evaluation of juvenile king salmon (Oncorhynchus 

tshawytscha)' loss in Clifton Court Forebay. Calif. Dept. Fish and Game, 

Anad, Fish. Br. Admin. Rept. No, 78-21. 

Skinner, J. E. 1974. A functional evaluation of a large louver screen installation and fish facilities research on California water diversion projects, 

pp. 225-249. In: L, D. Jensen (ed.) Proceedings of the Second Entrainment and IntakyScreening Workshop. Johns Hopkins University Coo ling Water 

Research Project, Report No. 15. 
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Spencer, 3, 1928. Fish screens in California irrigation ditches. Calif. 

Fish Game 14(3):208-210. 

Wales, J, H. 1948. California fish screen program. Calif. Fish Game 38(2): 

45-51. 

, E, W. Murphey, and J. Handley, 1950. Perforated plate fish 

screens. Calif. Fish Game 36(4) :392-403. 

L 
EXPLANATION OF THE FISH SCREEN LIST 

(APPENDIX) 

Screen: The fish screens are listed by Department of Fish and Game region 

and then alphabetically.bycounty and water. 

Installation Date: Most of the installation dates of the currently operating 

screens are available, although a few estimates had to be made. 

Period of'operation:. In most cases, the period of operation of the screens is 

based on weather, time of fish migration, location of the screen, and the 

water temperature (John Eggs, Fish Habitat Supervisor 11, Calif. Dept, 

Fish and Game, pers. comm.). 

Type:. The various types of screens were discussed in the previous section. 

Diversion: Where two numbers appear, they represent the normal and maximum 

flow diverted in cfs. A single number represents the best estimate of designed

diversion, 

Bypass: Water bypassing the screens and returning to the stream is described 

by two numbers: (1) the normal, and (2) the maximum bypass flow (cfs).

Single numbers represent normal bypass flows. 

Approach Velocity: 

screen and may not: reflect the actual velocity at all times, 

This is a calculated velocity of water approaching the 
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