studies along these lines should include investigations into the matter 

 of operating speed of screens, approach velocity to the screens, and the 

 welfare and disposition of adult fishes within the influence of the pumps. 



To complete its function, the screen must be provided with a by-pass 

 of sufficient capacity, and of certain dimensions to carry the fish to a 

 point of safety within the shortest time possible. An integral part of 

 the screen structure should include means of collecting fish from the 

 screen and transferring them to the intake of the by-pass canal. These 

 are details that must be worked out by engineers in collaboration with 

 fishery biologists. 



Several alternate plans for transporting juvenile fish collected by 

 the screen have been proposed. The initial plan proposed that the by- 

 pass originate in the vicinity of Mossdale on the San Joaquin River. 

 From this point it would follow Paradise Cut, a short stretch of Tom 

 Paine Slough, thence through about 12 miles of new canal constructed 

 along the southwest side of the Delta to the screen structure. From 

 this point it would be necessary to construct another 15 miles of new 

 canal to the lower section of Dutch Slough, which empties into the San 

 Joaquin River upstream from Antioch, California, and is considered to 

 be sufficiently removed from pump influence to assure safety of the fish. 



This by-pass canal, approximately 33 miles in length, would have a ■ 

 capacity of 500 cubic feet per second, and would derive its entire flow 

 from the San Joaquin River by means of a 12 foot concrete diversion dam. 

 This structure would provide a 10 foot head at the point of diversion. 

 This canal would be continuous and would pick up fish collected at the 

 screens. 



This plan, as well as one which proposed a by-pass flow of 500 cubic 

 feet per second originating a't the screen structure, was abandoned because 

 of complexity and prohibitive costs. 



The plan currently in favor proposes a by-pass canal of 200 cubic 

 feet per second capacity originating at the screen structure and termina- 

 ting in Dutch Slough. ' It would be supplied by means of water pumped from 

 the approach canal. The channel would have a total length of approximately 

 15> miles, all of which would have to be constructed, since there are no 

 natural channels which could be used along its route. To assure the 

 maintenance of water temperatures as low as possible and to attain maximum 

 safety from predators, this canal should be made as deep as possible 

 consistent with its capacity. 



The adequacy of the channel and its volume of flow can only be deter- 

 mined under actual maximum operation of the project. If changes are 

 warranted at that time, they should be made. 



U3 



