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11. Musselshell River Drainage 



The Musselshell River is tributary to the Missouri River in central 

 Montana. The southern drainage divide extends between the Bull Mountains 

 and the Crazy Mountains, while the northern divide extends from the 

 Castle Mountains through the Little Belt and Snowy Mountains, to the 

 Judith Mountains. The drainage contains approximately 8,000 square 

 miles and contains the following DNR&C designated basins: 40A, 40B, 

 40C. Stream classification ranges from B-Dj to B-D3 (DHES). 



Forestland ownership in the basin is predominantly USPS. Private (and 

 other) ownerships of merchantable timber occur along the lower slopes 

 of the basin's drainage divides. Non-USFS logging occurs in the Bull 

 Mountains and the Crazy Mountains, as well as other locations. 



Due to the dry climatic conditions and scarcity of perennial streams 

 in the region, timber harvesting generally has only a minor effect on 

 water quality (DHES, 1976). Impacts from these activities are outlined 

 in Table VI-Cll and located on Plate I . 



Most erosion occurring in the Musselshell River basin ^s due to natural 

 geologic conditions (BLM, 1971). Timbered areas usually produce sediment 

 at a comparatively low rate (BLM, 1971) and this is generally true in 

 the Musselshell basin. However, the local Conservation Districts (1977) 

 have estimated that 42 percent of the commercial timber acreage (within 

 the USGS sub-basin 10040202) is contributing to non-point sediment 

 pollution. This may indicate the presence of an environmentally critical 

 area (i.e., erosive soil conditions developed on Upper Cretaceous and 

 Tertiary sediments), in this drainage segment. 



Land management activities can aggravate these conditions; range! and, the 

 dominant basin land use, has also contributed to non-point sediment pollution, 



