INTERAGENCY ECOLOGICAL STUDY PROGRAM 

FOR THE SACRAMENTO-SAN JOAQUIN ESTUARY 

DELTA FISH FACILITIES TECHNICAL COORDINATING COMMITTEE 

-

WORKING JUSTIFICATION PAPER NO. 1 

"Justification For Proceeding With An 

"Off-River" Intake Concept For The Peripheral Canal'' 

. 

August 1979 
JUSTIFICATION FOR PROCEEDING WITH AN 

'YEF-RIVER~* INTAKE CONCEPT FOR THE PERIPHERAL mdI 

INTRODUCTION 

This is a 'korking justification paper" that presents the rationale 

for the present direction of the Delta Fish Facilities Program, It 

was prepared by the Delta Fish Facilities Technical Coordinating

Gomiittee whose members include both biological and engineering staff 

of the Interagency Ecological Study Program for the Sacramento-San 

Joaquin Estuary. As a "working" document it is subject to change

based on new findings, policy redirection, financial and other constraints. 

This paper recommends that the Fish Facilities Program effort proceed with major emphasis on the "off-river" intake cdncept, The 

ff on-river" concept should be considered a less desirable, but secondary approach, and the "in-canal" concept should be abandoned. Figure 1 has a generalized sketch of each of the three concepts, 

-I/ Prepared by the Delta Fish Facilities Technical Coordinating Committee, part of the Interagency Ecological Study Program for the 

Sacramento-San Joaquin Estuary whose members include: California 

f Department of Fish and Game, California Department of Water Resources, U, S, Bureau of Reclamation, and U. S, Fish and Wildlife 

Service. 
0 Fish Screen 

I 

Screen 

Peripheral Canal Intake Configurations 
DISCUSSION 

I 

. Initial planning for the Peripheral Canal intake and fish screens 

envisionkd a simple turnout from the river, with a fish protective

facility located several miles downstream in the canal. Although

11.igM.y desirable from the engineering design and cost side, this facility, the I tin-canal'' facility, had a number of significant drawb"cLcE= s from the biological side of the program. The main points of 

issue were: 

1. The predation losses anticipated in the settling

basin and canal ahead of the fish protective facility. 

2. Handling losses of juvenile fish which would be incurred in the operation of the fish facility. 

3, Uncertainties as to our ability to develop a pump

and conduit return system capable of safely returning the salvaged fish to the main river, a distance 

of several miles. 

4. A reluctance to expose the fish to a screen in a 

deadend channel, a situation, which in our experience, results in major operational problems, 

- These concerns were of sufficient import to cause a major change in 

program direction. 

The "on-river" intake and fish screen location was then proposed to 

relieve the concerns associated with the "in-canal" system. Essentially, by moving the intake to the river's edge, the biological

problems associated with handling fish trapped at the "in-canal" 

facility were eliminated by leaving the fish in the river. Predation problems in the settling basin and canal were also eliminated. 

However, the concept posed a new series of design, construction,

operation, and biological concerns. 

Construction and operation of the "on-river" facility would be considerably more difficult than for the "in-canal'' facility. ;Construction would require protecting and dewatering the bank of the river 

while the levee was removed and a fish screen structure installed. 

Operation of the "on-river'' facility would require continuous manipulation of the gates controlling the flow through the screen structure, This operation would be required to niaintain the water velocity

through the screen within our standards in the presence of a tidal 

reversal at the screen face. 

Further, protecting the intake works from winter debris loads, navigation traffic, and sedimentation would have presented substantial 

problems, The sedimentation problems were demonstrated to be of major 

concern by hydraulic model studies recently completed by U. C. Davis. 
t -3-

Biologically, t;he "on-river" concept presented two major concerns. 

First, fish could be exposed to the fish screen for the duration of 

a tidal reversal (up to 6 hours), since at that time water would be 

flowing from both up and down river to the screen. Secondly, an 

unknown, and relatively unmanageable predator population could establish itself at the screen face. These concerns, coupled with the 

difficulty of assuring a uniform flow through the fish screen in a 

tidal reversal situation led to the formulation of a third, intermediate concept. 

The "off-river" concept utilizes a new side channel to the river in 

which the fish screen is located. Construction could then take lace behind the existing levee, easing the problems presented in the p:on2-iver" configuration. Operational problems would be minimized by

providing a constant downstream flow in the "off-river" channel. 

This would require a low head pump to overcome the tidal reversal in 

the new channel. Adjustments to the flow control gates would be 

minimized by this system. 

hoblems with wineex debris loads and navigation traffic would also 

be more readily solved. Finally, the hydraulic model studies recently

completed at U, C. Davis demonstrated the potential for minimizing

sediment entrainment with this intake design. 

Biologically, eliminating the tidal reversal at the screen face reduces the stress on the fish by reducing the duration of exposure.

Also the new side channel is a more manageable situation in terms 

of controlling anticipated predator populations. Identifying a lowhead pump, which fish will pass through readily and safely,'is a 

major unresolved need being studied. However, to assure the constant 

dawnstream flow in the side channel, some sort of a low-head pump

will be required, Although not as rigorous a test as the "in-canal" 

situation, this problem remains a major unresolved question in the 

seudy program, Additionally, predator problems associated with the 

fish return system may require additional studies. 

CONCLUSION 

? 

The Delta Fish Facilities Technical Coordinating Committee recommends 

ehe program effort be directed to resolving the remaining "off-river'' 

questions at this time. We further recommend the "on-river'' concept

be relegated to a secondary, fallback position, which cannot be 

developed in time to meet our present deadlines, since no work on the 

problems assocrated with this concept is being pursued. Finally, we 

recommend that the "in-canal" concept be abandoned.