Application of the Montana Nonpoint Source Stream Reach Assessment 



materials (less than 6.35 mm) and substrate 

 scores obtained by the fisheries study. (See 

 Module D.) Again, the correlation was not 

 significant. 



Discussion 



Given that the assessment procedure is sub- 

 jective and nonquantitative, we expect less ac- 

 curacy or resolution in identifying subtle 

 nonpoint source pollution impairment. The 

 impaired streams assessed in the Flathead Ba- 

 sin are more likely to have subtle (rather than 

 major) impairment. Our assessment results did 

 not correlate well with activity levels or with 

 quantitative fisheries habitat evaluations that 

 indicated impairment to spawning or rearing 

 habitat. 



Of the "pristine" non-managed reaches as- 

 sessed, 30 percent were rated as impaired. Two 

 of these streams (Granite and Morrison Creeks), 

 have management activity in the upper reaches. 

 The impaired, non-managed reaches were lo- 

 cated downstream and generally exhibited very 

 poor channel stability. These problems may or 

 may not have been influenced by upstream 

 management activity. The assessment proce- 

 dure is meant to identify natural or hydrologic 

 as well as nonpoint source pollution influences 

 on stream condition. Admittedly, it is difficult 

 to do this. However some reaches that have no 

 management activity may be naturally impaired. 

 They may exhibit channel instability or occur in 

 erosive geology. Such reaches may not fully 

 support beneficial uses. 



One could argue that natural conditions 

 should not be considered as "impairment." Water 

 pollution laws certainly do not apply to natural 

 impairment. However, it is important to recog- 

 nize that natural conditions may impair fisher- 

 ies habitats. Although it is unlikely that natural 

 impairment can or ever will be addressed, re- 

 source managers should consider such natural 



"impairment" when evaluating future land man- 

 agement activities. 



Ideally, the impairment rating of the assess- 

 ment procedure should be tied to beneficial 

 uses. Our comparisons of assessment results 

 and fisheries habitat data generally yielded poor 

 correlations. This indicated that the assessment 

 resolution or accuracy may not be suitable in 

 areas of subtle impairment (such as in the Flat- 

 head Basin). This is not surprising since the 

 method was designed to assess the most severe 

 problems in the state. 



Conclusions 



The surveyor observed tree blowdown due 

 to inadequate streamside management zones, 

 sediment from poor road maintenance, logging 

 slash in the stream channel, and bank trampling 

 by livestock as the primary causes of stream 

 problems related to management practices. Al- 

 though these activities negatively influenced 

 stream conditions, they where not always con- 

 clusively tied to impairment of beneficial uses. 



In areas of relatively subtle nonpoint source 

 pollution impairment and/or erosive geology 

 (as in many of the Flathead Basin study streams), 

 the assessment procedure did not adequately 

 separate natural factors from management in- 

 fluences. 



Eight out of 1 6 initial assessment categories 

 were generally not applicable to the study 

 streams. Of the eight assessment categories 

 used to determine impairment values for this 

 study, most were potentially influenced by, but 

 not directly tied to, management activity. 



The assessment results generally revealed 

 less impairment than the results of the quantita- 

 tive fisheries habitat studies. This indicates that 

 the assessment procedure either does not iden- 

 tify or underestimated impairment to beneficial 

 uses. 



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Flathead Basin Cooperative Program Final Report 



