biological information will also provide 

 a basis for comparisons of the runs in 

 future years. During 1956 and 1957 the 

 Service made studies on ( 1 ) the size and 

 time of migration of various species 

 past the dam site, (2) the rate of travel 

 of migrating fish pastRocky Reach Dam 

 site before the dam is built, and (3) 

 tributary spawning areas used by 

 various segments of the run. 



To accomplish these objectives we 

 have used the fish-count data at Rock 

 Island Dam for determining the size 

 and time of escapements atRocky Reach 

 Dam site 21 miles upstrecim. Tagging 

 experinnents provided information on 

 the rate of travel of blueback Sedmonj 

 and strejmi surveys in which spawning 

 salmon were counted in the streams 

 were used for obtaining salmon spawn- 

 ing data. 



Financial support for this study 

 was provided by Public Utility District 

 No. 1 of Chelan County, Washington. 



SALMON RUNS PAST ROCKY REACH 

 DAM SITE 



Over the years salmon become 

 specifically adapted to their environ- 

 ment and become established in certain 

 strecims and watersheds in varying 

 abundance. The purpose of the in- 

 vestigation was to determine the abun- 

 dance of these upriver runs and the 

 arrivcil times of these runs at the new 

 Rocky Reach Dam site. 



Since it was not possible to count 

 fish there, the arrival times of the 

 runs at Rocky Reach Dam site was 

 estimated from a study of the arrival 

 times of fish at Rock Island Dam 21 

 miles downstream. The daily counts 

 of salmon and steelhead were graphed 

 to show the seasonal pattern of migra- 

 tion, and by applying known rates of 

 travel of different species, we were 

 able to estimate their arrival times 

 at Rocky Reach Dam site. 



The size of escapements passing 

 Rocky Reach Dam site was estimated 

 by applying to the Rock Island Dam 

 count the ratio of spawners observed 



in spawning streams above and below 

 Rocky Reach Dam site. Totals of peak 

 salmon counts for the Wenatchee River 

 system and river systems above Rocky 

 Reach were compiled, and a ratio ob- 

 tained of the number of spawners found 

 in the two areas. This ratio was then 

 applied to the escapement counted at 

 Rock Island Dam to obtain an estimate 

 number of fish passing Rocky Reach 

 Dam site. For example, if 1,000 

 spawners were counted in all streams 

 and 700 were observed in streams above 

 Rocky Reach, then 70 percent were 

 deemed to have passed Rocky Reach. 

 Thus, if 10,000 Chinook had been counted 

 at Rock Island Dam, 7,000 fish would 

 be estimated as having passed Rocky 

 Reach Dam site. 



Stream surveys were made peri- 

 odically by foot or by boat and the num- 

 ber of fish of each species of salmon 

 was recorded. Peak counts, which were 

 the largest number counted in any one 

 survey, becamie the basis of compari- 

 sons. Survey counts do not represent 

 the total number of spawners present in 

 a stream in a season. Such information 

 cannot be obtained from stream sur- 

 veys. However, as these survey counts 

 were taken in the Scune manner and by 

 the same personnel, we feel they gave 

 a usable estimate of the comparative 

 abundance of spawners in the different 

 streams. 



Time and size of runs passing Rocky 

 Reach Dam site 



Blueback salmon were found to 

 migrate upriver at the rate of 13.5 

 miles per day (see later section); thus, 

 they would be expected to pass Rocky 

 Reach Dam site, 21 miles upstream 

 from Rock Island Dam, by the second 

 day after passing Rock Island Dam. 

 Chinook salmon in the Snake River 

 were reported to naigrate at rates of 

 13 and 15 miles per day.* Either of 

 these rates indicates that chinook runs 

 passing Rock IslandDam would pass the 



Thompson, Robert N„ James B. Haas, Lawrence M. 

 Woodal, and Edwin K, Holmberg. 1958. Results of a tagging 

 program to enumerate the numbers and to determine the 

 seasonal occurrence of anadromous fish in the Snake River 

 and its tributaries. Fish Commission of Oregon, Contract 

 Report DA 35-026-eng-20609, Portland, 202 pp. Processed, 



