Application of the Montana Nonpoint Source Stream Reach Assessment 



sessed, 46 percent were rated as impaired. (See 

 Figure E^.) 



In comparing the individual assessment 

 categories, "Land Use" contributed to impair- 

 ment on 72 percent of the assessed reaches. 

 "Land Use" is a measure of potential risk. It is 

 based primarily on the distance from the stream 

 that management activity has occurred. Chan- 

 nel stability and substrate composition contrib- 

 uted to impairment on approximately 30 per- 

 cent of the assessed reaches. Figure E-5 sum- 

 marizes the percentage of reaches where sp)e- 

 cific assessment categories contributed to im- 

 pairment. 



The character and extent of management on 

 identified stream reaches varied considerably 

 throughout the Flathead Basin. Of the 95 as- 

 sessed reaches, 75 were managed to some ex- 

 tent and 20 were unmanaged or "pristine." 

 Timber harvest and the presence of roads ac- 

 counted for the majority of management activi- 



ties. However livestock grazing occurred on 

 several reaches. 



Of the "managed" stream reaches assessed, 

 48 percent were impaired to some extent, and 

 52 percent were unimpaired. Of the unimpaired 

 reaches, 33 percent were rated as threatened. 

 (See Figure E-6.) 



While conducting assessments, the surveyor 

 identified several management activities as ei- 

 ther contributing to stream impairment or hav- 

 ing a good potential to cause problems. The 

 surveyor attributed observed sedimentation to 

 timber harvest, roads, and livestock. The pri- 

 mary problems were inadequate streamside 

 management zones for logging units, poor road 

 surface maintenance, and bank trampling by 

 livestock. Table E-2 summarizes this infor- 

 mation. 



Of the 20 unmanaged stream reaches as- 

 sessed, 40 percent were impaired and 60 per- 

 cent were unimpaired. (See Figure E-7.) The 



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Flathead Basin Cooperative Program Final Report 



