WEATHER AND RIVER DISCHARGE DATA 



Headwater and tailwater elevations are 

 plotted on figures 1 and 2. Air temperatures 

 were taken twice daily by maximum and mini- 

 mum thermometer. A continuous record of 

 water temperatures was taken by thermograph 

 at the middle fish ladder. Daily records of 

 weather conditions and stream flows are shown 

 in tables 9-14. 



Average daily river discharge data are 

 plotted on figure 3. Maximum daily discharge 

 of 451,900 c.f.s. on June 17 exceeded the 

 1963 record high discharge of 308,400 c.f.s. 

 which also occurred on June 17. 



Maximum water temperature of 64° F. oc- 

 curred August 18, 22, and 23. In 1963, maxi- 

 mum water temperature of 65° F. occurred 

 August 6-10, 13, 16, and September 6-12. 



ACTIVITIES AND OBSERVATIONS 



The waterflow was reduced in the right 

 fish ladder on April 28, 1964, from 9:15 to 

 11:15 a.m. to clear the submerged orifices 

 and remove accumulated debris. The flow of 

 water was again reduced in this ladder on 

 August 31 from 1:00 to 2:10 p.m. to repair 

 broken chains on an adjustable weir. The 

 left ladder was closed to fish migration on 



October 1 5 to permit repairs to the auxiliary 

 water trash rack and to the diffusion box 

 grating. The middle ladder was inoperative 

 from October 15-24 in order to make repairs. 



As part of an evaluation study of effects of 

 Wanapum Dam reservoir encroachment on 

 the ladders at Rock Island Dam, a program 

 of trapping and tagging was conducted by the 

 Bureau of Commercial Fisheries. Chinook 

 were taken in a floating trap at exit of the 

 left ladder, and sockeye were taken by a 

 trap at the counting station inside the left 

 ladder. All fish taken were tagged with num- 

 bered Petersen disks and released about 1,000 

 feet below the dam in equal amounts on each 

 bank of the river. Trapping and tagging was 

 conducted May 19-28 for chinook and July 15 

 to August 5 for sockeye. A total of 103 chinook 

 and 955 sockeye were tagged and released. 

 Numbers of tagged fish returning through the 

 ladders were: chinook, 92; sockeye, 898. 



Two chinook salmon tagged by the Fish 

 Commission of Oregon on the lower Columbia 

 in early spring were observed passing over 

 Rock Island Dam in May. 



On several occasions during the counting 

 season, spillway gate operations were changed 

 to improve ladder approach conditions. 



During early spring of 1964 and prior to the 

 counting season, modifications were made to the 

 middle ladder auxiliary water supply structure. 



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



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