Table 7. — Distribution of passage times of individual Chinook salmon, sookeye salmon, and steelhead trout through the 

 4.3-m. introductory pool of the 0.6-m.-diai!ieter pipe with and without a truncated entrance cone, May-August 1964 



95 percent confidence intervals about the median. 



fish were delayed somewhat b-y the 180° turns. 

 Rates of passage were faster in the illumi- 

 nated than in the nonilluminated pipe, except 

 in the third straight section where passage 

 was slightly faster in the nonilluminated pipe. 

 Under both light conditions the fastest pas- 

 sage was in the second straight section of the 

 test pipe. 



Water Depth 



The object of the tests in 1964 was to de- 

 ternnine the influence of a partly filled pipe 

 on fish passage in a 0.6-m. -diameter pipe. 



Water depth in the partly filled pipe was about 

 30.5 to 35.6 cm., which left a 25.4 to 30.5 cm. 

 air space; water velocity was 0.9 m.p.s. 

 Salmon and trout were tested in the 82.3-m. 

 pipe with two turns and a straight 27.4-m. 

 length of pipe. Passage times through a flooded 

 and partly full pipe were used to measure the 

 effect of water depth on fish passage. 



Passage times of fall chinook salmon and 

 steelhead trout were fastest in the partly filled 

 pipe (table 10). Willingness to enter the pipe 

 was about the same under the partly full or 

 flooded pipe conditions. 



12 



