PROGRESS IN BIOLOGICAL INQUIRIES, 1930 597 



take this electric screen has diverted a considerable number of fish 

 and thereby justified its use. 



Old Indian Canal elective screen. — As commented on in the 1929 

 report the Old Indian Canal which diverts water from the Yakima 

 River and discharges it into lateral No. 1 of the Wapato Canal had, 

 in its unscreened condition, permitted a large amount of fish to enter 

 the Wapato system last year. To remedy this condition the Bureau 

 of Fisheries installed an electric screen at the Old Indian Canal 

 intake in the spring of 1930. 



The screen employed was of the grounded type as has been pre- 

 viously described. Its location was just in front of the head gate and 

 at a slight angle with it. At this location water is diverted into the 

 canal by means of a low rock and brush dam. It was possible to 

 maintain a favorable by-pass fiow adjacent to the screen for the 

 majority of the time. 



If fish enter the Old Indian Canal they are discharged directly 

 into lateral No. 1 of the Wapato Canal and are thus accounted for in 

 the check of fish in the Wapato system. Water velocities at this 

 location are not unreasonably high, and this factor along with the 

 good by-pass facilities prevailing here argues well for the successful 

 operation of this electric screen. 



Tieton. electric screen. — The Tieton Canal of the United States Rec- 

 lamation Service diverts water from Tieton River at a point about 35 

 miles northwest of Yakima, Wash. The capacity of the canal is 

 approximately 320 second-feet and this flow is maintained throughout 

 the irrigation season. The screen is as described in the 1929 report, 

 being of the grounded type consisting of a curtain of chain electrodes 

 spaced 24 inches center to center and a ground element of anchor 

 chain, all being located outside of the canal head gates. 



Check of fish left stranded in the Tieton system together with 

 observations regarding fish conditions along the Tieton River above 

 and below the head gate and in the canal itself indicates satisfactory 

 functioning of the electric screen at this installation. 



N aches power house electric screen. — In the early summer of 1930 

 the Pacific Power & Light Co. electrized the screen which they had 

 installed the previous year under the supervision of the bureau. This 

 installation is located at the head of the Wapatox Canal, which 

 diverts water from the Naches River for use at the Naches and the 

 Drop power plants near Yakima, Wash. The ditch has a capacity 

 of about 600 second-feet. The screen is of the grounded type, consist- 

 ing of a curtain of chains and a ground element of pipe laid in 

 contact with the bed of the concrete-lined canal. This screen is 

 located a short distance down the canal from the head gates and 

 adjacent to the spillway which, throughout the spring and summer 

 months, offers an excellent by-pass channel for return of fish to the 

 river. 



Observation of fish conditions in the Naches River in the vicinity 

 of this diversion and inspections of the canal itself from time to time 

 during the summer indicated the high efficiency of this screen. Dur- 

 ing the period that an adequate by-pass was maintained, which was 

 during the principal migration season, it is estimated that at least 

 90 per cent of the fish entering the Wapatox Canal were diverted 

 through the by-pass hy the electric screen. 



