Fish Populations 



In 2002, we duplicated fish 

 population sampling at four long- 

 term monitoring sites established in 

 1989. The combined CPUE for both 

 bull trout and WSCT show continued 

 static densities in Copper Creek 

 (Figure 20). Following the fire in 

 2000, bull trout redd counts declined 

 73 % in the inde.x reach of Copper 

 Creek compared with 2002 and 

 declined 80% compared with the long 

 term mean of 20 redds (1989-2002). 

 Future monitoring will attempt to 

 assess the fire and post-fire related 

 impacts to Copper Creek nafive fish. 



Figure 20. CPUE for bull trout and WSCT > 4" for 

 Copper Creek (1989, 1999 and 2002). 



Cottonwood Creek 



Restoration objectives: improve degraded habitat; eliminate fish losses to irrigation 

 ditches; and restore migration corridors for native fish. 



Project Summary 



Cottonwood Creek, a large tributary to the middle Blackfoot River originating 

 near Cottonwood Lakes, flows 16-miles to its junction with the Blackfoot River at river 

 mile 43. Cottonwood Creek supports bull trout, WSCT, rainbow trout, brown trout and 

 brook trout. WSCT and bull trout dominate the headwaters. Genetic testing of WSCT in 

 Cottonwood Creek in 2003 showed no introgression (Appendix J). Rainbow trout inhabit 

 the lower mile of stream while brook trout and brown trout dominate middle stream 

 reaches. 



Impacts to fish populations and their habitats were present throughout the 

 Cottonwood Creek drainage, although most of the identified private land problems were 

 corrected during the 1990s. Completed restoration measures involve water conservation 

 and water leasing, upgrading irrigation diversions with fish ladders, fish screens at large 

 diversions, and implementation of riparian grazing changes. In 2002, the last open 

 irrigation ditch was closed during a flood-to-sprinkler irrigation conversion. In 2003, 

 diversion deficiencies were corrected at the Dreyer Diversion by replacing the existing 

 diversion with a cross-vane diversion. 



We also assessed a road-crossing problem related to an undersized culvert at 

 stream mile 15.9. This undersized and perched culvert causes severe channel 

 downcutting and high erosion immediately below the culvert, along with aggradation 

 below the incised reach (Dave Rosgen, personal communication). This instability 

 appears to contribute to the loss of surface flows during base flow periods and isolation of 

 fish between the dewatered section and the perched culvert. We measured a decrease in 

 flows from 0.4 cfs to the complete loss of surface flow over a distance of 765' in 



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