tween pools affects passage time in a 

 fishway of a given slope. In the l:8-slope 

 fishway, three rises between pools (1.0, 

 1.5, and Z.O feet) were under study during 

 the season. A fairly large group of fish 

 was timed up the fishway for each rise. 

 Although species composition of each 

 group was not the same (see table 7), it 



is believed that the median elapsed times 

 may be connpared as each time would 

 reflect the passage time, in general, of 

 the fish passing Bonneville during that 

 period. Figure 10 indicates a direct rela- 

 tionship between height of rise between 

 pools and passage time required to ascend 

 a total rise of 6 feet. 



Table 6. — Passage times of groups of steelhead 

 in morning and afternoon periods in both 

 fishways, July and August 1956. 



\J Number entering fishway; species composition is based on fish leaving 

 fishway during test period. 



Table 7. — Passage times and species composition of three groups 



of fish ascending three variations of a l:8-slope fishway 



for a total rise of 6 feet, August 1956. 



Date 



Rise Number Median 

 between oi—' elapsed 

 pools fish time 



Species composition 



Steel- Blue- 



head Silver back Other J/ 



Chinook 



Number of fish 



48 



26 

 1 



3 



\J Number entering fishway; species composition is based on fish leaving 



fishway during test period. 

 2/ Suckeis ( Catostomus sp) and squawf ish (Ptvchocheilus sp) . 



10 



