and is well above the 27-year mean of 2,946 

 (table 1). Monthly totals of steelhead trout 

 counted are given in table 2. 



Maximum day's count in I960 was 198 on 

 September 20 (table 3). 



Additional data pertaining to steelhead trout 

 daily counts are contained in tables 6-11. 



Semimonthly totals of number and percent- 

 age of steelhead trout ascending each fish 

 ladder are given in table 14. 



Miscellaneous Fish 



In 1960, 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 identi- 

 fication 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 1960, 

 approximately 150,660 fish other than salmon 

 and steelhead trout passed Rock Island Dam. 

 Species of fish included are: largescale 

 sucker, Catostomus macrocheilus Girard; 

 longnose sucker, Catostomus catostomus 

 (Forster); squawf ish, Ptychocheilus orego- 

 nense (Richardson); Rocky Mountain whitefish, 

 Prosopium williamsoni (Girard); Columbia 

 River chub, Mylocheilus caurin us (Richardson); 

 chiselmouth, Acrocheilus alutaceus Agassiz 

 and Pickering; carp, Cyprinus carp to Linnaeus; 

 Dolly Varden trout, Salvelinus malma (Wal- 

 baum); and rainbow trout, Salmo gairdneri 

 Richardson. 



WEATHER AND RIVER DISCHARGE DATA 



Figure 1. --Headwater 

 May 210 



Rock 

 I960. 



Island Dam, 



Figure 2.--Tailwater elevations, Rock Island Dam, 

 May 2 to October 29, 1960. 



Headwater and tailwater elevations are 

 plotted on figures 1 and 2, respectively. Water 

 and air temperatures were taken by pocket 

 thermometer. Water temperatures given are 

 average of morning and afternoon surface 

 readings. Daily records of weather conditions 

 and stream flows are shown in tables 6-11. 

 Daily river discharge data are plotted in 

 figure 3. 



ACTIVITIES AND OBSERVATIONS 



Arrival time of the first chinook salmon 

 at Rock Island Dam in 1960 was 15 days 

 earlier than in 1959. In spite of this early 

 arrival of fish, the peak day's movement of 

 chinook salmon occurred on August 3, 70 

 days later than in 1959. 



