484 U. S. BUREAU OF FISHEEIES 



would be prohibitive in cost, the best solution of the problem would 

 be to gradually stock the lake with fall-spawning fish and protect the 

 pumping plant by means of removable steel racks which would have 

 to be held in place for only a short time each year. The company is 

 being asked to provide these racks and to cooperate in bearing the 

 cost of a new hatchery which is to be built on Bear Lake by the 

 Bureau of Fisheries and the State of Utah. 



ELECTRIC FISH SCREENS 



In three previous reports of this division there is presented the his- 

 tory and development of the electric fish screen and its use by the 

 Bureau of Fisheries up to the start of the irrigation season of 1931. 



The experimental work conducted in the sluiceway at Gold Ray 

 power house and at the Fort Klamath hatchery in the fall of 1930 

 demonstrated the superiority of the insulated type of screen over the 

 old-style grounded installation, and led to the adoption of this im- 

 proved type on all installations maintained by the Bureau of Fish- 

 eries. The improved type of screen consists of a double row of 6-inch 

 diameter pipe electrodes fabricated from No. 20 gage galvanized 

 iron. These electrodes, properly weighted at the lower end, are sus- 

 pended in the water from supporting cables. The most effective 

 spacing has been found to be 4 feet center to center of pipes in rows 

 with 6-foot spacing between rows. Electrification is accomplished 

 with 60-cycle alternating current at a potential ranging from 55 to 65 

 volts. Convenient voltage regulation is provided by means of a 

 transformer specially tapped on the secondary side and designed to 

 carry a sustained short circuit. 



Three years of operation with the electric screen has disclosed the 

 weaknesses of this type of fish-protective device. The chief difficulty 

 is in the antagonism which is likely to develop in the public mind 

 when some fish are killed or stunned by contact with the electrified 

 water. Such attitude entirely disregards the' fact that the electric 

 screen may be operating to save the majority of fish, but it creates a 

 problem in public relations which can not be overlooked. Further- 

 more, the action of the electric screen can never be expected to be 

 100 per cent effective as is the mechanical screen. Another difficulty 

 is the patent situation, which raises a restriction which can be avoided 

 by use of the mechanical screen. For these reasons the investigators 

 do not recommend the electric fish screen for general use. In the 

 case of the electric screens operated on United States Government 

 projects in the Yakima country the situation is somewhat different. 

 There the bureau itself operates the screens, giving them very careful 

 attention and supervision, and in Yakima County. Wash., alone the 

 use of the electric screen is free from patent royalties. These Yakima 

 screens undoubtedly save a large proportion of the fish, and it is felt 

 that the continued use of these particular electric screens is justified. 



Sunmfside electric screen. — The Sunnyside Canal, main diversion 

 of the Yakima project of the United States Eeclamation Service, 

 diverts water from the Yakima River near Yakima, Wash. The 

 capacity of the canal is 1,500 second-feet. The diversion period of 

 1931 extended from February 20 to October 20. During the period 



