Figure 2. — Physical facilities of experimental fish-giiidmg site at Prosser, Wash. Waterflow is from right 

 to left. Experimental canal (A) had V-type electrode array, an array trap, and a water- velocity control 

 structure to divert excess flow through water-bypa.ss channel (B). The water-bypass channel was 

 screened at both ends to prevent entry of fish. Arrow points to rotary drum screens used to evaluate fish- 

 guiding efficiency of electrical field created by electrode array- Yakima River Is in background. 



which was excavated adjacent and parallel to the 

 Chandler Canal. 



The bypass channel was about 1.2 m. deep, 288 

 m. long, and 64 m. wide. It carried the excess flow 

 when reduced velocities were desired in the experi- 

 mental canal. Both ends of this bypass channel 

 were screened to prevent entry of fish (fig. 3) . Each 

 screen support structure consisted of a wooden 

 framework, 72 m. long and 3 m. high, equipped 

 with guides to accommodate 69 individual screens. 

 Each screen was about 0.9 m. wide, 3 m. high, 3.2 

 mm. thick, and constructed of perforated steel 

 plate. The perforations were 6.4 by 25.4 mm. ovals 

 that provided a 46 percent opening. A traveling 

 hoist on an overhead I-beam was used to lift the 

 screens for cleaning. Each screen bay was fitted 

 with a double set of guides so that a second screen 

 could be installed before the first was removed. 



The screen support structure at the entrance to 

 the water-bypass channel was also equipped with 

 guides to accommodate stoplogs. The stoplogs, con- 

 structed of concrete, were about 0.9 m. long, 0.6 ra. 

 liigh, and 5.1 cm. thick. An overhead hoist, similar 

 to tliat used for lifting the screens, was used to 

 raise and lower these stoplogs. 



Another structure, at the upstream end of the 

 main experimental canal and just downstream from 

 the entrance to the water-bypass channel, was also 

 used to help regulate the water velocity (fig. 4). 

 This structure was constructed in the form of four 

 V's joined together (WW) and was placed in 

 the experimental canal at 90° to the flow. The struc- 

 ture was connected to each bank by earth-filled 

 wooden abutments. The sides of each V were 

 equipped with guides to accommodate 15 solid ply- 

 wood panels. An overhead hoist raised or lowered 



FISH-GUIDING EFFICIENCY OF AN ELECTRICAL GUIDING SYSTEM 



309 



