I'll 



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



J_L 



5 10 15 20 25 

 MAY 



5 K> 15 20 25 

 JUNE 



5 10 15 20 25 

 JULY 



5 10 15 20 25 

 AUGUST 



5 10 15 20 25 

 SEPTEMBER 



5 10 15 20 25 

 OCTOBER 



Figure 2. — Tailwater elevations, Rock Island Dam, May 1 to October 24, 1964. 



During 1964, fish were observed with cuts 

 or abrasions on their heads and bodies. 

 Of the 114,439 salmon and steelhead observed 

 as they passed over the counting boards, 



2,225 fish, about 2 percent, had injuries 

 (table 21). This same percentage of injuries 

 was noted in 1963. Since in both years the 

 counters could see only the top and one 



20 



