56 - 



B. Clark Fork River Basin 



The Clark Fork River receives waters from most of Montana west of the 

 Continental Divide; it is tributary to the Columbia River. The northern 

 portion of the watershed (Flathead and Lake Counties) is within the 

 Flathead Designated 208 study area and was not considered in this report. 

 To simplify discussion of water quality problems, the following desig- 

 nations were made: 



Upper Clark Fork River Basin Headwaters to mouth of 



Blackfoot River 



Middle Clark Fork River Basin Mouth of Blackfoot River to 



mouth of Flathead River 



Lower Clark Fork River Basin Mouth of Flathead River to 



Idaho stateline 



Various drainage reaches and problems areas are discussed within each 

 designated basin: 



Upper Clark Fork River Basin 



The Upper Clark Fork River has its headwaters along the Continental 

 Divide. There are significant forest resources contained within the 

 basin, surrounding broad sediment filled valleys. Much of the timber- 

 land is administered by the USFS. Silvicultural activities on the basin's 

 timberlands have resulted in some degradation of water quality. Those 

 problem areas occurring on non-USFS lands are discussed in the text. 

 Other land uses that contribute non-point pollution include agriculture, 

 mining, and urbanization. 



Local Conservation Districts have estimated that approximately seven percent 

 of the commercial forest acreage is contributing to non-point source 

 sediment pollution within the basin (1977). 



