and full support of aquatic life uses at both sites. The site above Cyclone Creek shared only 38% 

 of its diatom flora with the site at Tally Lake Campground. 



Modal Categories (Table 5) 



Several ecological attributes assigned by Stevenson and Van Dam et al. (1994) were 

 selected from the diatom reports in the appendix and modal categories of these attributes were 

 extracted to characterize water quality tendencies in Logan Creek (Table 5). 



The majority of diatoms at all three sites on Logan Creek were non-motile nitrogen 

 autotrophs that prefer fresh waters and low BOD levels. However, the modal category for 

 oxygen demand declined from "continuously high" at the upstream sites to "moderate" at the 

 downstream site, indicating a decline in the availability of dissolved oxygen. The modal 

 categories for pH and trophic state also shifted from the upstream sites to the downstream site, 

 indicating significant increases in alkalinity and concentrations of inorganic phosphorus at Tally 

 Lake Campground. 



