higher. Larger values generally indicate favorable biotic conditions. On the other hand, 

 the percent filterers metric may range from 0% to 100%, in this case, larger values are 

 negative indicators of biotic health. To facilitate scoring, therefore, metric values are 

 transformed onto a single scale. The range of each metric has been divided into four parts 

 and assigned a point score between zero and three. A score of three indicates a metric 

 value similar to one characteristic of a non-impaired condition. A score of zero indicates 

 strong deviation from non-impaired condition and suggests severe degradation of biotic 

 health. Scores for each metric were summed to give an overall score, the total 

 bioassessment score, for each site in each sampling event. These scores were expressed 

 as the percent of the maximum possible score, which is 18 for this metric battery. 



The total bioassessment score for each site was expressed in terms of use-support. 

 Criteria for use-support designations were developed by MT DEQ and are presented in 

 Table 3a For descriptive purposes, scores were also translated into impairment 

 classifications according to criteria outlined in Table 3b. 



