Maximum day's count in 1961 was 269 on 

 September 19 (table 2), 



WEATHER AND RIVER DISCHARGE 

 DATA 



Table 6 shows semimonthly totals of number 

 and percentage of steelhead trout which as- 

 cented each fish ladder. 



Miscellaneous Fish 



In 1961, enumeration was made of species of 

 fish other than salmon and steelhead trout 

 passing Rock Island Dam, Data pertaining to 

 these fish are given in tables 15-20. No claims 

 are made as to complete accuracy of identifi- 

 cation of these fish. It is felt, however, that 

 the degree of accuracy is consistent with that 

 maintained at other dams on the Columbia River 

 and as such may be used as a rough index of 

 abundance of these fish. In 1961, approximately 

 140,280 fish other than salmon and steelhead 

 trout passed Rock Island Dam. 



Headyvater and tailwater elevations are 

 plotted on figures 1 and 2, respectively. From 

 1 p.m. on June 9 through June 13 all fish facili- 

 ties were nonfunctional due to high water. Air 

 temperatures were taken twice daily by pocket 

 thermometer. Water temperatures were taken 

 at center fish ladder by recording thermometer. 

 Daily records of weather conditions and stream 

 flows are shown on tables 9-14. Daily river 

 discharge data are plotted on figure 3, 



ACTIVITIES AND OBSERVATIONS 



A count of 137 Chinook salmon on May 1 

 indicates that initial movement of these fish 

 probably began prior to that date. This is in 

 striking contrast to the late start of fish on 

 May 18, 1959. 



5 10 15 20 25 5 10 15 20 25 5 10 15 20 25 5 10 IS 20 25 5 10 15 20 25 5 10 15 20 25 



"»'' JUNE JULT AUGUST SEPTEMBER OCTOBER 



Figure l.—Headwater elevations. Rock Island Dam, May 1 to October 27, 1961. 



