total release had passed the lower weir (ele- 

 vation 54) from the time at which half of the 

 total entered had passed the upper weir (ele- 

 vation 60), Fallbacks were accounted for by- 

 excluding the next fish following. 



RESULTS 



The following analysis treats performance 

 of both individual salnnonids and groups of 

 salmonids in accordance with various test 

 conditions (table 1) established in the labora- 

 tory version of the Ice Harbor fishway (fig. 13). 



Individuals 



Individual salmonids tested under proposed 

 fishway operating conditions (test condition 1) 

 included chinook and sockeye salmon and 

 steelhead trout in the full-width and half- width 

 fishway. 



Chinook.- -T-wo hundred and forty- nine chi- 

 nook were timed in the full-width fishway and 

 253 inthe half-width fishway (table 2). A com- 

 parison of median passage times (10.5 min- 

 utes and 7.1 nninutes, respectively) indicated a 

 significantly faster passage in the half-width 

 fishway. Inspection of the mean passage times 

 also reflected a faster ascent under the half- 

 width fishway condition. Figure 14 presents a 

 graphic connparison of these ascents. 



Steelhead . --Pas sage times of individual 

 steelhead in the full-width and half-width fish- 



way were similar (table 2 and fig. 14). The 

 median passage time for 78 individuals ascend- 

 ing the full-width fishway was 5.5 minutes, 

 whereas the median passage time for similar 

 ascents of 151 steelhead in the half- width fish- 

 way was 4.8 minutes. The difference between 

 these times was not significant. Mean passage 

 times for ascents during the full-width and 

 half-width conditions were virtually the same 

 (6.8 minutes and 6.7 minutes, respectively). 



Sockeye .- - The median passage time for 35 

 individuals ascending the full-width fishway 

 was 2.8 minutes, while the median passage 

 time for similar ascents of 51 sockeye in the 

 half-width fishway was 5.0 minutes (table 2). 

 The difference in passage times was not sig- 

 nificant. Mean passage times were virtually 

 the same--7.6 minutes in the full-width fish- 

 way and 7.5 minutes in the half-width fish^way. 



Groups 



Group releases of mixed species were made 

 in the full-width and half-width fishway 

 (table 3). While species connposition of the 

 groups varied, either chinook salmon or 

 steelhead predominated in individual tests. 

 Passage times, therefore, were considered in 

 accordance with the dominant species in a 

 given test. 



Chinook .- -All chinook group releases 

 (table 4) were made during test condition 1 

 (table 1). Median elapsed passage times for 

 the four tests in the full-width fishway ranged 



Figure 13.--The six-pool full-width test section of the Ice Harbor fishway design under 



proposed operating conditions. 



