INTERAGENCY ECOLOGICAL STUDY PROGRAM FOR THE SACRAMENTO-SAN JOAQUIN ESTUARY

DELTA FISH FACILITIES TECHNICAL COORDINATING COMMITTEE



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WORKING JUSTIFICATION PAPER NO. 1

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

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August 1979JUSTIFICATION FOR PROCEEDING WITH AN 'YEF-RIVER~* INTAKE CONCEPT FOR THE PERIPHERAL

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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 theFish 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 theDeltaFish Facilities Technical Coordinating Committee, part of the Interagency Ecological Study Program for the Sacramento-San Joaquin Estuarywhose 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



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Screen

Peripheral Canal Intake ConfigurationsDISCUSSION

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. Initialplanning for the Peripheral Canal intake and fish screens envisionkd a simple turnout from the river, with a fishprotective facility located severalmiles 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"

cLc E=s from the biological side of the program. Themain points of issue were: 

### 1. The predation losses anticipated in the settling basin and canal ahead of the fishprotective facility.


### 2. Handling losses of juvenile fishwhichwould 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 severalmiles.
4. A reluctance to expose the fish to a screen in a deadend channel, 

### a situation,which in our experience, results inmajor operational problems,



### - These concerns were of sufficient import to cause amajor change in program direction.
The "on-river" intake and fish screen locationwas 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" facilitywere 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" facilitywould be considerably more difficult than for the "in-canal'' facility. ;Constructionwould 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'' facilitywould require continuous manipulation of the gates controlling the flow through the screen structure, This operationwould be required to niaintain the water velocity through the screenwithin our standards in the presence of a tidal reversalat the screen face. Further, protecting the intakeworks fromwinter debris loads, navigation traffic, and sedimentationwould have presented substantial problems, The sedimentationproblems were demonstrated to be ofmajor 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 

### 6hours), since at that time water would be flowing fromboth up and down river to the screen. Secondly, an 

### unknown, and relativelyunmanageable predator population could establish itself at the screen face. These concerns, coupledwith 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 

### lowhead pump to overcome the tidal reversal in the new channel. Adjustments to the flow control gates would be minimized by this system. hoblems withwineex 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 fishby reducing the duration of exposure. Also the new side channel is amore manageable situation in terms of controlling anticipated predator populations. Identifying a lowhead pump, which fishwill 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-headpump willbe required, Although not as rigorous a test as the "in-canal" situation, this problem remains amajor unresolved question in the seudy program, Additionally, predator problems associatedwith the fishreturn systemmay require additional studies.

CONCLUSION

? The Delta Fish Facilities Technical CoordinatingCommittee 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, fallbackposition, 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.