more apparent when the internal reference was used. 



In this analysis, the Marias River was rated non-impaired. The lowest scoring site, 

 Pondera Coulee Vi mile from its mouth, received less than half of the score of the Marias River 

 site. The other Pondera Coulee site, south of Cheek's bridge was rated slightly impaired in this 

 analysis. . > 



CONCLUSIONS 



• Organic and/or nutrient enrichment limited biotic health at four of six of these Plains 



ecoregions sites. Only the site on the Marias River and the Sage Creek site showed little 

 impact from water quality problems. Though near its headwaters, the upstream site on 

 Corral Creek also had some indication of water quality impairment, even though an 

 abundance of pollution-sensitive taxa were collected there. 





Sediment deposition may limit biotic health at both sites in Pondera Coulee, though data 

 from the downstream site near the Marias River suggested this more strongly than that 

 from the upstream site. Sediment impacts are also indicated at the Marias River site, and in 

 Sage Creek. 



The internal reference derived from the data collected from these streams provided a 

 useful tool for comparison of the streams to each other, and seemed to provide a more 

 discriminating assessment than did the ecoregion reference. 



