Table 2. — Median and mean passage times of individual chlnook, steelhead, and sockeye ascending 

 six pools of the Ice Harbor flshway under full -width and half -width conditions, May 10 to 

 September 20, 1960 (test condition 1, table 1) 



■"■ Confidence intervals for 



^ Based on fish completing 



♦Significant 



N.S. Not significant. 



Figure 14. — Comparison of ascents of individual salm- 

 onids in the full-width and half-width fishway (test 

 condition 1, table 1). Number of fish completing the 

 ascent by 1-minute intervals expressed as a cumula- 

 tive percent of total tested, June 8 to September 14, 

 1960. 



from 6.6 minutes to 11.2 minutes. The average 

 median elapsed time was 9.4 minutes. Two 

 group releases conducted simultaneously in 

 both sides of the divided fishway had median 

 elapsed times of 8.8 minutes and 8.2 minutes. 

 Results of group tests generally agree with 

 those of tests with individual fish; that is, the 

 fish passed faster through the half-width fish- 

 way than through the full-width fishway. 



the median derived from table A-25, Dixon and Massey (1957). 

 six-pool ascent in 1-hour period. 



Steelhead .- -Group tests of steelhead (table 4) 

 were conducted under test conditions (table 1). 

 Two group releases in the full-width fishway 

 showed median elapsed times of 3.7 minutes 

 and 7.2 minutes. In the half-width fishway, 

 median elapsed times for six tests ranged 

 from 4.7 minutes to 9.7 minutes with an aver- 

 age time of 6.7 minutes. Included were two 

 tests in which fish were released simultane- 

 ously into both sides of the divided fishway.' 

 While there was a sizable range in passage 

 times among the different tests, the data 

 generally indicate that steelhead performed 

 as well in the half-width fishway as in the 

 full- width fishway. 



Fishway Capacity Trials 



Elling and Raymond (1959) and EUing (I960) 

 described experiments in which large numbers 

 of fish passed through a 1-on- l6-slope fishway 

 of pool-and-overfall design without orifices. 

 In one of the largest releases, 50 fish per 

 minute were passed through a 4-foot-wide 

 fishway for 20 minutes without any indication 

 that the capacity of the fishway had been 

 reached. 



During the experiment described here, four 

 tests were made with a half-width section of 

 the 1 -on- 10-slope Ice Harbor fishway (table 5). 

 Performance, expressed as median elapsed 

 time, was fairly constant during the test series, 

 though sample sizes ranged from 460 to 1,371 

 fish. In June I960, two tests, composed pri- 

 marily of Chinook salmon, showed median 

 elapsed passage times of 7.1 and 7.9 minutes. 



10 



