Canvas Light Baffles 



Plywood Cover 



\ 









V 





Plunging Flow 



Canvas Light Baffles 



/ 





\ 



y, 



Figure 2. — Schematic illustration of test area (fishway) showing ply- 

 wood co-'/er, canvas baffles, and plunging flow pattern in 

 side view. 



in the upper end. Square crested weirs 

 7 1/2 inches wide were painted white on top 

 to facilitate observing the fish as they 

 passed in and out of the fishway. The head 

 on each weir, measured four feet upstream 

 of the weir, was 0.8 foot. The flow pattern 

 was that generally described as "plunging 

 flow" (figure 2). 



For the "dark" or test trials, the 

 fishway was covered with plywood sheets and 

 sealed with canvas strips (figure 3). To 

 reduce the light entering the entrance and 

 exit of the resulting fishway tunnel, canvas 

 baffles were extended from the plywood cover 

 to within two inches of the water surface in 

 the center of both first and last pools (fig- 

 ure 2). To further reduce the light enter- 

 ing the fishway the laboratory was darkened. 



Light readings y 

 foot candle in the co 

 entry gate (figure 1) 

 foot candle at the fi 

 (the upstream end of 

 and at the last weir 

 observations made in 

 the fishway indicated 

 register in the humcin 



ielded values of 0.1 

 llection pool near the 

 , and 0.01 and 0.02 

 rst weir of the fishway 

 the introduction pool) 

 of the fishway. Visual 

 the central portion of 



insufficient light to 



eye. 



For the "light" or control trials, the 

 plywood covering was removed and 1000-watt 

 mercury-vapor lajnps were suspended six feet 

 above the fishway (figure 4) and six feet 

 apart (raecisured center to center) down the 

 center of the fishway. These Isimps provided 

 light intensities at the surface of the 

 fishway pools ranging from 300 foot candles 



measured along the wall to 1000 foot ccuidles 

 directly beneath the lights. This range of 

 light intensities approximates outdoor con- 

 ditions on a bright, cloudy day. 



Water temperatures varied from 65.5" 

 F. to 66.0° F. on the two days the experi- 

 ment was conducted — July 23 cuid 24, 1957. 

 Turbidimeter and Secchi's disc readings 

 yielded values of 10 (equal to 10 p. p.m. 

 Si02) and 4.5 feet respectively on both days. 



PROCEDURE 



The experiment consisted of four con- 

 trol and four tests trials. As only one 

 fishway was used, the control and test 

 trials were conducted alternately. Averages 

 of 26 and 21 fish were utilized for each 

 control and test trial respectively. The 

 species composition for the four groups 

 passed under the dark (test) condition WM 

 82 steelhead and 1 chinook, and for the four 

 groups passed under the light (control) con- 

 dition, 100 steelhead aind 3 chinook. 



About 10 to 15 minutes before begin- 

 ning a test trial, we darkened the building 

 to permit the observers to adapt their eyes 

 to the limited light. At the end of this 

 time, the observers could count the fish as 

 they passed through the entry gate and over 

 the white weir crests of the fishway. 



An observer stationed at the collec- 

 tion pool initiated each test and each 

 control trial by opening the entrance gate. 



