Near Mouth. An increase in the percentage of freshwater species (e.g., Fragilaria 

 vaiicheriae) indicates a decrease in sahnity at this site and at the Hutterite Colony. However 

 both of these sites were dominated by Nitzschia ainphihioides, which prefers waters that are 

 "rich in electrolytes" (Krammer & Lange-Bcrtalot 1988). Diatom metrics indicate minor 

 impairment from sedimentation and organic loading. This site had somewhat depressed species 

 richness, di\'ersity, and equitability values, each of which indicates minor stress. This site 

 shared only 24% of its diatom assemblage with the Taylor site, which indicates a major 

 difference in environmental conditions between the two sites. 



Hutterite Colony. This site is just downstream from the preceding site. Although this 

 site was sampled over a month later than the other site, they shared almost two thirds of their 

 diatom assemblages and were \'irtually identical in temis of diatom species composition and 

 metric values (Table 4). Both sites had pollution index and siltation index values that suggest 

 minor impairment, and both sites had slightly depressed species richness, diversity, and 

 equitability values that suggest minor stress. 



Sand Creek. This site shared several major taxa with Prairie Elk Creek and had metric 

 values very similar to those at Garoutte's. Diatom metrics for Sand Creek suggest moderate 

 impairment from sedimentation and organic loading. Other metrics were normal for a prairie 

 stream. This site had a higher percentage of nitrogen-fixing diatoms than all of the sites on 

 Prairie Elk Creek except Taylor's, which suggests that Sand Creek is nitrogen-limited. 



Modal Categories (Table 5) 



Several ecological attributes were selected from the diatom reports in the appendix and 

 modal categories of these attributes were extracted to characterize water quality tendencies in 

 Sand Creek and Prairie Elk Creek (Table 5). 



