PROGRESS IN BIOLOGICAL INQUIRIES^ 19 31 485 



of maximum irrigation demand, which is also the period of chief 

 migration of lish, this canal carried in excess of 1,000 second-feet. 



This screen is of the new, improved insulated type, consisting of a 

 double row of pipe electrodes located in the forebay in front of the 

 headgates. This year the location of the screen was moved upstream 

 and out of the river as far as practicable in order to escape the higher 

 water velocities which existed at the old site. 



In addition to this main electric screen there was installed an 

 auxiliary screen of similar type extending out from the upstream 

 end of the main installation at right angles to the shore line for a 

 distance of 24 feet. The purpose of this auxiliary screen is to give a 

 preliminary warning to downstream-migrating fish as they approach 

 the diversion point, and thus it is hoped to divert these fish before 

 they enter the higher water velocities which exist at the main screen. 



As previously commented uf)on, water conditions at Sunnyside 

 Dam at certain times produce very severe operating conditions affect- 

 ing the electric screen. The crest length of Sunnyside Dam is 500 

 feet. During practically the entire irrigation season flashboards are 

 maintained along the crest raising the water surface approximately 

 2.5 feet. At the center of the dam is located a large concrete fish- 

 way built by the Bureau of Fisheries in 1929. This ladder consti- 

 tutes the chief by-pass channel at the Sunnyside installation. It 

 undoubtedly serves many downstream migrating fish, especially those 

 that travel down river along the west shore. However, it has long 

 been recognized as desirable to have a by-pass channel located close 

 to the electric screen which is situated at the east abutment of the 

 dam. To this end, early in July a stem gate was installed in the 

 logway which extends through the dam close to the downstream end 

 of the electric screen. 



In the operation of any by-pass at the Sunnyside diversion the 

 main difficulty is lack of water. The irrigation season of 1931 was 

 the most critical short-water year in the history of the Yakima 

 project. The Sunnyside diversion is the lowest Government diver- 

 sion on the Yakima River, and at times the entire flow of the stream 

 is diverted directly into Sunnyside Canal. At such times practically 

 all the flow comes from storage reservoirs maintained by the Gov- 

 ernment, and all of this storage water is contracted for and sold to 

 the irrigation interests. When these irrigation requirements exceed 

 the available flow, there is no adequate by-pass flow available for 

 the conservation of fish life. 



There were times in the summer when there was practically no 

 overflow, but whenever even a small amount of water was available 

 for this purpose, the ready cooperation of the Reclamation Service 

 insured that it was jDut through the by-pass channels. 



Gold Ray intake screen. — Early in April the intake screen at Gold 

 Ray power house of the California-Oregon Power Co. was put 

 into operation at a point upstream of the trash rack at the intake. 

 This screen, also, was of the improved insulated type, consisting of a 

 double row of pipe electrodes. This year the screen was installed at 

 an angle with the intake in the hope that such location would en- 

 courage use of the newly improved north bank fishladder as a by-pass 

 for downstream-migrating fish. It proved, however, that close 

 proximity to the steel trash rack was an unfavorable factor, it being 



