The benthic assemblage sampled at McCloud station scored maximal values for 

 all but one of the bioassessment metrics, resulting in a total score indicating excellent 

 biotic health. Full support of designated uses was indicated. The percentage of filter- 

 feeding organisms was higher than expected for an unimpaired site. At Johnstone station, 

 on the other hand, mayfly richness, stonefly richness and caddisfly richness were all 

 lower than expected in undisturbed conditions, and no sensitive taxa were collected. In 

 addition, a large proportion of sampled organisms were tolerant, and a large proportion 

 were filter-feeders The total bioassessment score calculated for the assemblage sampled 

 at this site indicated moderate impairment of biotic health and partial support of 

 designated uses. 



Table 5. Metric values and bioassessments for Shields River, August 2000. 



1. Classifications; (NON) non-impaired, (SLI) sUghUy impaired, (MOD) moderately impaired, (SEV) 



severely impaired. See Table 3b. 



*Use support designations; See Table 3a. 



Aquatic invertebrate communities 



Shields River at McCloud station supported a benthic assemblage typical of a 

 weatem Montana stream with little disturbance. The community was diverse (37 taxa 

 were present in the sample) and most functional components were adequately 

 represented. Nine percent of the sampled assemblage were fiher-feeders, a proportion 



