diatom algae, both sites supported a mix of green algae and 

 cyanobacteria, and a single genus of chrysophyte {Tribonema) . 

 Ten genera of non-diatom algae were found at the upstream site 

 and seven genera at the downstream site (Table 5) . As with the 

 other streams in this study, the algal flora of Sandbar Creek 

 indicated cool waters of low mineral content. 



Willow Creek. Diatoms accounted for most of the biovolume 

 in the periphyton sample collected at WilC-Ol and the chrysophyte 

 Tribonema ranked second at this site (Table 5) . Nine other 

 genera of green algae and cyanobacteria, most of them indicating 

 cool waters of low nutrient and low mineral content, made up the 

 rest of the flora. 



The filamentous green alga Ulothrix dominated the periphyton 

 sample from WilC-02, followed by Chaetophora (filamentous green), 

 Audouinella (filamentous red) , and Tolypothrix (filamentous 

 cyanobacterium) (Table 5) . These algae also indicate cool waters 

 with relatively low nutrient and mineral content. 



DIATOMS 



Blackfoot River. Most of the major diatom species in 

 samples from the upper Blackfoot River are sensitive to organic 

 enrichment (Table 6) . However, Synedra rumpens , the dominant 

 species at the Flesher Pass Road, is somewhat tolerant of organic 

 loading (Lange-Bertalot 1979) . Organic loading at this site, 

 which is also reflected by the borderline pollution index (2.50), 

 may be internal and due to the naturally swampy nature of the 

 stream at and above this location. 



Aside from minor organic loading and disturbance, and a 

 slightly elevated percent dominant species value at the upstream 

 site, the most serious problem in the upper Blackfoot River 



10 



