Figure 6. M.F. Koyukuk River valley looking upstream. 



coarse and fine-grained deposits associated with moderate to steep sloped 

 mountains and hills; bedrock exposures are limited to upper slopes and 

 crestlines (Figure 7). The area is underlain by discontinuous permafrost. 



Normal temperature ranges in the Northern Interior are from 2 to 20 C 

 in the summer and -30 to -8 C in the winter. The annual precipitation is 

 about 28-38 cm, which includes 190-210 cm as snow. 



The valleys in the Dietrich River-Middle Fork Koyukuk River region 

 are heavily wooded with both steep, timbered slopes and gently sloping 

 terraces adjacent to the river. The slopes are vegetated primarily with 

 stands of white spruce and paper birch. In the Jim River-Prospect Creek 

 area, the valleys are heavily wooded with white spruce and paper birch 

 and a thick understory. Resident fish species found in the Koyukuk River 

 system include burbot, Dolly Varden or Arctic char, Arctic grayling, long- 

 nose sucker, northern pike, slimy sculpin, round whitefish, inconnu, and 



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