PROGRESS IN BIOLOGICAL INQUIRIES, 1929 1101 



tinue to work up along the edge to the unelectrified section of channel 

 occupied by the trap. After several weeks of operation, during 

 which time many fish were stopped by the electric screen, but none 

 were found to enter the trap, further work with the latter was 

 abandoned. 



Throughout the season many people had an opportunity to observe 

 hundreds of salmon and steelhead in contact with the electric 

 field. Some of these fish were stopped at the weak fringe of electri- 

 cal effect just downstream from the ground pipe. The majority 

 would penetrate the electrified zone for from 5 to 8 feet, where they 

 would Dreak water in a mighty leap and, turning around, swim 

 rapidly out of the tailrace. A very few fish were seen to pass 

 through the screen, but this Was exceptional. A happy feature of the 

 season's operation was the almost complete absence of killing or 

 stunning of fish due to contact with the electric field. High success 

 has attended the operation of this screen. It is estimated that, 

 during the summer, upward of 5,000 salmon and steelhead attempted 

 to pass through the electric field. Brief shutdowns of the power 

 house were made upon several occasions for cleaning fish out from 

 above the screen. The results of these checks indicate that the 

 efficiency of the screen may conservatively be taken as from 95 

 to 98 per cent. 



Electrification of Savage Rapids sateen. — At the Savage Rapids 

 Dam on the Rogue River the Grants Pass irrigation district operated 

 a pumping plant to deliver a total of 110 second-feet of water to two 

 high-line ditches. Several years ago the Oregon Game Commission 

 installed a " roller-towel " type of mechanical screen in front of 

 the intakes to prevent downstream migrating salmon and steelhead 

 from being sucked into the turbines. With this large-mesh screen 

 remaining stationary it is known that great numbers of small fish 

 are drawn through it to the turbines. This summer, at the request 

 of the Oregon Game Commission, and with that body and the 

 Oregon Fish Commission bearing the expense, the United States 

 Bureau of Fisheries converted the installation to an electric screen. 

 In this work Prof. F. O. McMillan served in a consulting capacity. 



Naches power house electric screen. — In February, 1929, the 

 Pacific Power & Light Co. annoimced its willingness to install at 

 its own expense electric fish screens at the company's power intakes 

 in Yakima County and requested the United States JBureau of Fisher- 

 ies to specify and design the screen ; accordingly the bureau specified 

 the materials and designed the screens for the Naches and Fruitvale 

 plants. These screens were similar to the installations being made in 

 the Government ditches. 



FISH LADDERS 



The field work of 1928 included the inspection of practically all 

 fish ladders in the States of Washington, Oregon, Idaho, and Mon- 

 tana. Studies of these installations and observations of the habits 

 of migratory fish revealed certain basic principles which should 

 govern the design of fishways. The activities of 1929 have included : 

 (1) The practical application of these basic principles in the con- 

 struction by the United States Bureau of Fisheries of a new fish 

 ladder at the Sunnyside Dam of the Yakima project. United States 



