Figure 2. — Pool and weir dimensions of the Ice Harbor fishway design. 



Ice Harbor Fishway Design 



The new 1-on- 10-slope fishway is a pool- 

 and-overfall type with submerged orifices, 

 flow stabilizers, and a nonoverfall section in 

 the middle of each weir (fig. 2). There is a 

 1-foot rise between pools, and average water 

 depth under normal operating conditions is 6.5 

 feet. 



The six-pool laboratory installation was 

 constructed of wood so that it could easily be 

 modified to produce a variety of test conditions. 



Test Conditions 



Performance offish in the Ice Harbor fishway 

 design was compared under both normal opera- 

 tional conditions and experimental situations 

 (table 1). During special tests, we modified the 

 weir crest design and fishway hydraulics and 

 compared the resulting fish passage under 

 full-width and half- width fishway conditions. 

 A narrow partition in each pool, which in 

 effect created two 8-foot-wide fishways, pro- 

 duced the half-'width fishway condition (figs. 

 1 and 3). 



Underwater facilities were provided for 

 viewing fish and fishway hydraulics. 



Table 1. 



-Test conditions during fishway 

 evaluation tests 



Proposed normal fishway operation. 

 ^ Orifices closed. 

 ^ No overfall on weir. 



