streams above Brownlee Dam. Several impound- 

 ments in the Snake River system above Brownlee 

 Reservoir support populations of kokanee (0. 

 nerka) ; these fish periodically move into the 

 Brownlee area. 



After the decline of the native runs, hatchery- 

 reared Chinook, coho (0. kisutch), and sockeye 

 salmon were released in the Snake River above 

 Brownlee Reservoir by the BCF in 1964 and 1965 

 to provide additional fish for study. 



The study on the passage of juvenile salmon and 

 trout from Brownlee Reservoir began in July 1963 

 and continued through the summer of 1965. I 

 report here the number and size of emigrants and 

 the time of emigration. 



TECHNIQUES OF SAMPLING AND 

 ANALYSIS 



The sampling area (fig. 1) was immediately 

 below Brownlee Dam. About 180 m. below the 

 powerhouse the turbine tailrace channel enters 



the original river channel, which carries the inter- 

 mittent discharges from the spillway of the dam. 

 The Interstate Bridge crosses Oxbow Reservoir 

 about 600 m. downstream from the dam. At that 

 point, the reservoir is about 160 m. wide and 3.5 

 m. deep at midchannel when Oxbow Reservoir 

 is at full pool. 



The primary sampling site was in the turbine 

 tailrace, about 150 m. below the powerhouse. The 

 turbine tailrace is about 76 m. wide; the water is 

 about 4 m. to 7 m. deep, depending on the level 

 of Oxbow Reservoir and the discharge from Brown- 

 lee Dam. Because fish that passed over the spillway 

 could not be sampled at the tailrace site, an addi- 

 tional sampling site was established downstream 

 at the Interstate Bridge for use during periods of 

 spillwdy operation. 



The analyses of the data involved an evaluation 

 of (1) equipment, (2) procedures, (3) tests of 

 sampling efficiency, and (4) methods of computing 

 emigration. 



Figure 1. — Turbine tailrace (foreground) at Brownlee Dam with scoop traps in position below right 

 bank. Spillway (not in operation in this photo) enters original river channel on extreme left. 



246 



U.S. FISH AND WILDLIFE SERVICE 



