ANNUAL FISH PASSAGE REPORT - ROCK ISLAND DAM 

 COLUMBIA RIVER, WASHINGTON, 1961 



by 



Paul D. Zimmer, Fishery Biologist (Management) 

 and John H. Broughton, Fishery Technician 



ABSTRACT 



Important runs of salmon and steelhead trout pass Rock Island Dam on the 

 Columbia River. 



Count of 33, 067 Chinook salmon in 1961 was well above the mean of 15,560 for the 

 28-year period 1933-60 and exceeded the 1960 count of 26,532. Sockeye salmon count 

 of 19,233 was slightly more than one-third the 28-year mean of 53,079. Only 50 coho 

 salmon were recorded in 1961. Greatest number of coho salmon, 229, occurred in 

 1947. The 7,042 steelhead trout passing Rock Island Dam in 1961 was the highest 

 count recorded since counting began in 1933 and was more than twice the 28-year 

 mean of 3,063. 140,173 fish other than salmon and steelhead trout passed through 

 the fishways at Rock Island Dam in 1961. 



INTRODUCTION 



Rock Island Dam, located on the Columbia 

 River approximately 12 miles downstream 

 from the city of Wenatchee, Wash., has been 

 in operation since 1933. The plant is owned 

 and operated by Chelan County Public Utility 

 District No. 1. 



This report on passage of fish at Rock Island 

 Dam during 1961 provides information on 

 operation of fishways and numbers of fish 

 utilizing upstream fish passage facilities. 



Rock Island Dam is now equipped with three 

 fishways: one located on the right bank. 



Note.- -Paul D. Zimmer and John H. Broughton. 

 Bureau of Commercial Fisheries, Columbia Fisheries 

 Program Office, U.S. Fish and Wildlife Service, Port- 

 land, Ore. 



another on the left bank, and the third ap- 

 proximately in the center of the dam. Two of 

 the fish ladders were placed in operation in 

 1933, and the third (middle ladder) was con- 

 structed in 1935-36. All three ladders have 

 undergone significant modifications since 

 initial construction. 



Included in this report are comments cover- 

 ing various investigations carried on at Rock 

 Island Dam during 1961. 



COUNTING PROCEDURES 



Fish counting in 1961 began on May 1 and 

 terminated on October 27. From May 1 to 

 August 19, counting was conducted 16 hours 

 each day, starting at 5 a.m. and ending at 

 9 p.m. From August 20 to September 30, to 



