I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 



I I I i ' ' I I I i I I I l I i i i I I i I i i I ; i i i I I i i i i i 



5 10 15 20 25 

 MAY 



10 15 20 25 

 JUNE 



10 15 20 25 

 JULY 



5 10 15 20 25 

 AUGUST 



5 10 15 20 25 

 SEPTEMBER 



10 15 20 25 

 OCTOBER 



Figure 3. — Daily river discharge, Rock Island Dam, May 1 to October 24, 1964. 



side of each fish, the incidence of injury- 

 might have been greater than observed. Of 

 the total number of injured fish observed in 

 1964, about 56, 23, and 21 percent were 

 recorded in the left, middle, and right ladders, 

 respectively. In 1963, these percentages were 

 64, 19, and 17. As in previous years, the 

 greatest number of injuries was observed on 

 the large chinook and sockeye salmon. In the 

 2-week period July 16-31, 52,431 sockeye 



were counted through the fishways and injuries 

 noted on about 2 percent of them. In 1963, 

 during the same period, about 4 percent of the 

 sockeye salmon observed had injuries. 



Throughout the counting season, State and 

 Federal fisheries personnel made frequent 

 inspections of fishway operations at Rock 

 Island Dam. Inspections were similar to those 

 conducted at other main stem dams where 

 fishways were being operated. 



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