Figure 11. — Two release compartments and introductory area of the Ice Harbor 

 flshway. Observer on right has opened gate to receive a fish from the collec- 

 tion pool. Observer on left has released a fish into the divided fishway and is 

 recording progress of the fish as it passes over weirs in the six-pool ascent. 

 Button switches on the handrail are used to transmit weir crossings to a time- 

 event operations recorder. 



of the fishway. Grillwork on the upstream side 

 of each of these orifices helped to prevent 

 fish from swimming back into the fishway 

 from the flow introduction pool and aided in 

 the observation of fish by deflecting them 

 toward the viewing window. 



In a model study, Corps personnel at the 

 Bonneville Hydraulic Laboratory tested the ob- 

 servation chamber at the head of the fishway 

 (weir 60) to determine its effect on fishway 

 hydraulics. They found no noticeable effect. 



Test Procedure 



Passage times required to ascend the six- 

 pool fishway were used to compare fish per- 

 formance under various test conditions. Pro- 

 cedures for release, timing, and comparison 

 of passage time varied slightly within different 

 types of tests. 



Types of tests. --Three types of performance 

 tests were made: Ascents by ( 1 ) individual fish, 

 (2) groups of mixed species, and (3) capacity- 

 type fish concentrations, which were similar 



to group releases but involved larger numbers 

 of fish 6. 



Release of fish .- -Individual fish were re- 

 leased from either of two release boxes 

 (fig. 11), but only one fish at a time was per- 

 mitted to enter the fishway. When the fishway 

 was divided, two fish one on each side of the 

 fishway, could be introduced simultaneously. 

 As soon as each fish completed the ascent, 

 another fish was released into the fishway. 

 Species were identified and length of fish esti- 

 mated as each fish passed through the release 

 box. 



Generally, the number of fish in a group 

 test ranged from 40 to about 300. After identi- 

 fication, these fish were permitted to enter the 

 test area as rapidly as possible. 



^ These tests were made to examine capacity-type 

 situations; that is, the maximum number of fish (size and 

 species considered) that could be passed through a fishway 

 of given size and hydraulic conditions. To approach a 

 capacity condition, it was necessary to get as many fish 

 as possible into the fishway in the shortest period of time. 



