Fry production was lower in 1997 compared to 1992. High flow conditions and flooding during 

 rainbow trout spawning and egg incubation in May and June likely resulted in scouring of 

 spawning gravel and may have contributed to relatively low spawning success. High flow 

 conditions also contributed to difBculties in trapping juvenile trout during peak movement periods 

 in July. An estimated 2,500 rainbow trout &y emigrated from Hell's Canyon Creek from 1 1 July 

 through 1 October 1997. This should not be considered an estimate of total fry production 

 because high flow prevented trapping during late June/early July when significant numbers of 67 

 typically migrate from the creek. Monitoring offish movement at the fish screen bypass indicated 

 that no fish were lost to the irrigation system, and approximately 1,000 trout were effectively 

 screened from entering the pipeline system. Comparisons of fiy captured at the fish screen bypass 

 and in Hell's Canyon Creek immediately below the irrigation withdrawal documented that about 

 40% of the fry would have entered the irrigation system had the fish screen not been present in 

 1997. 



Although there is no estimate of trout fiy numbers rearing in the stream downstream of the 

 pipeline withdrawal, rearing conditions for small trout were significantly improved in 1997 . 

 compared to 1992 because of improved stream flow. This improved rearing environment is 

 expected to provide increased survival of juvenile trout that would otherwise be forced to rear in 

 the Jefferson River. 



A-22 



