MOTOR 

 ^REDUCTION GEAR 

 T SHEAVE 



J^ POCKET SHEAVE 



POCKET SHEAVE 



Figure 6. — Horizontal traveling screen, model II. 



a 20° angle; the screen also began lifting at 

 an angle of 22°. By the time the screen reached 

 point H it had been lifted a distance of 61.0 cm. 

 The screen traveled at this height from H to 

 J, where it began descending. By the time it 

 reached F, the bottom of the screen was again 

 in contact with the floor. 



Support for the leading face of the screen 

 was identical to that on model I. A major 

 difference between the two systems was that 

 the drive unit and the tracking structure were 

 sloped in model II to bring the screen out of 

 the water for its travel upstream; all sheaves 

 and the track were placed on the same 22° 

 slope. 



METHOD OF TESTING SCREEN 



To test the traveling screen, we installed 

 it in a flume at the Carson National Fish 

 Hatchery near Carson, Wash., provided a 

 bypass, and tested fish in this system. 



Description of Flume 



The basic structure consisted of a wooden 

 flume (15.3 m. long, 1.8 m. wide, and 1.2 m. 

 deep) set against the left bank of Carson 

 Cr^ek. A clear plastic window (1.1 m, by 

 1.8 m.) was installed near the downstream 

 end of the flume to allow observation of re- 

 sponse by the fish. Test fish introduced at the 

 upstream end were recaptured at the down- 

 stream end of the flume by an inclined screen 

 and trap with a perforated plate. Water came 

 from Tyee Springs, several hundred meters 

 away, at a flow of 1.3 m.p.s., which could 

 be directed completely, or in part, into the 

 flume. 



Bypass 



A 30.5-cm.-wide bypass was constructed; 

 it was equal to the water depth, with an ac- 

 celeration of 135 percent of the approach 

 velocity to ensure acceptance by the fish. 



Test Fish 



Test fish were hatchery- reared spring 

 Chinook salmon, 8.9 to 15.3 cm, long, and coho 

 salmon, 5.1 to 7.6 cm. long. The fish were 

 dip-netted from a raceway and transported 

 in containers to the upstrean-i end of the flume. 

 Water velocities tested were 1.0, 0.8, and 0.5 

 m.p.s. All the fish that migrated down the 

 flume were guided by the screen into the 

 bypass and swept over an inclined screen 

 into a trap. 



EFFICIENCY OF THE SCREEN 



Placement of the traveling screen units at 

 a small (20°) angle to the flow enabled the 

 young fish to nnove into the bypass without 

 becoming impinged against the screen. 



All of the Chinook and coho salmon tested 

 at velocities of 0.5, 0.8, and 1.0 m.p.s. were 

 guided into the bypass and trap (table 1). 

 These high efficiencies were due to the perfect 

 operation of the sealing system (at either end 

 and along the canal floor) and the small size 

 of the screen mesh. 



Loss of head across the screen was small 

 for both models. The loss was higher on 

 model I because the screen remained in the 

 water during its return upstreann. There was 

 no indication that head loss could be reduced 

 by increasing the speed of the screen. 



To study the effect of debris on the traveling 

 screen we threw grass, nnoss, leaves from 



Table 1. --Summary ol' number of I'lsn ana number oi xests run at 

 different water velocities; all fish entered the bypass 



