PROGRESS IN BIOLOGICAL INQUIRIES, 192 9 



1099 



The efficiency of the Wapato electric screen can not be determined 

 from the numljer of fish left in the ditch at the end of the season 

 because, for a time, fish passed into tiie system through the Old 

 Indian Canal which was unscreened. Taking this into account, the 

 results indicate that the electric screen was a success. For the pur- 

 pose of comparison a check was made at the end of the irrigation 

 season on the Selah-Naches ditch where tliere is no screening device. 



This ditch, operated by a private irrigation company, diverts water 

 from the Naches River (a tributary of the Yakima) in the same dis- 

 trict with the Sunnyside and Wapato Canals. The ditch capacity 

 is about 300 second-feet. In the check up on this ditch there was 

 found a total of 5,900 salmon and steelhead 3 to 8 inches long. Of 

 this total 5,389 were actually caught and counted. All the fore- 



FlGURB 6.- 



-The Wapato electric fish screen. Chain electrodes are seen hanging in 

 front of the diversion gates 



going installations were under the competent care of W. N. Wagner, 

 inspector United States Bureau of Fisheries. 



Gold Ray intake screen. — The purpose of this electric screen is to 

 prevent downstream migrating salmon and steelhead from being 

 drawn into the power turbines. The Gold Ray Power House of the 

 California-Oregon Power Co. is situated on the Rogue River near 

 Medford, Oreg. Water is diverted to the turbines through an open 

 channel blasted in rock. The screen was electrified June 3, but re- 

 sults were not satisfactory. Experimentation with a view to im- 

 proving conditions was carried out throughout the summer. Early 

 in August a survey of the distribution of the electric field set up in 

 the water was made by Prof. F. O. McMillan. This revealed high 

 and undesirable voltage gradients at the chain electrodes and along 

 the masonry wall at the south side of the intake. 



