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5. Jefferson River Drainage 



The Jefferson River drainage is considered a headwater stream of the 

 Missouri River, extending from Twin Bridges to Three Forks and bounded 

 by the Continental Divide to the west, the Tobacco Root Mountains to the 

 south, and the Bull Mountains to the north. Designated as drainage basin 

 41G (DNR&C), the Jefferson River watershed is classified as B-Dj (DHES). 



Most forestland in this basin is under USPS ownership; however, there is 

 also BLM, state, and private ownership. Timber harvest on non-USFS lands 

 has been limited, due to the fact that there is relatively little mer- 

 chantable timber available on these lands. No impacts to water quality 

 from these activities have been identified. 



Moderate turbidities have been recorded in the Jefferson River drainage. 

 The primary causes for these problems are natural erosion, hydrographic 

 modifications, and agricultural practices (DHES, 1974). Local Conservation 

 Districts estimated that about two percent of the commercial forestlands 

 contribute to non-point sediment pollution. Weathered granitic and 

 volcanic materials within the drainage are susceptible to accelerated 

 erosion. 



Potentials for future water quality problems (from forestry practices) 

 are limited. However, there are two areas of mixed ownership (Bull 

 Mountains, Tobacco Root Mountains) where non-coordination of management 

 activities could result in water quality degradation. These are outlined 

 in Table VI-C5 and located on Plate I . 



