Burleigh and County Farm sites in May (Table 4) . Green algae and 

 cyanobacteria were also common at both sites. The Burleigh site 

 above Lewistown supported more than twice the number of algal 

 genera than did the County Farm site below Lewistown. 



In August, diatoms (Diatoma hyemalis) dominated the site 

 above Castle Creek just below the Big Springs. Two other 

 chrysophycean algae- -Tribonema and l/aucheria- -ranked 2nd and 3rd 

 in biomass here. All of these algae are typical of cold, spring- 

 fed streams. Green algae were absent from this site. 



The mat -forming cyanobacterium Phormidium dominated the 

 algal flora below Pike Creek in August (Table 4) . Diatoms were 

 common here and ranked second. Green algae were also absent at 

 this site, which supported only 2 genera of non-diatom algae. 



The filamentous and potentially nuisance- forming green alga 

 Cladophora dominated the algal flora of Big Spring Creek at the 

 two sites below Lewistown that were sampled in August (Table 4) . 

 Diatoms ranked 2nd in biovolume at both sites and cyanobacteria 

 were also present, especially as epiphytes on Cladophora at 

 BSPRC05. Replicate samples from BSPRC03 generated very similar 

 results (Table 4) . 



DIATOMS 



May Samples. Since they were collected outside of the 

 summer sampling "window", diatom metrics generated from the May 

 samples cannot be compared with the biocriteria in Table 3 . This 

 is because samples collected during the cool seasons in Montana 

 tend to be dominated by a single species. 



Nitzschia fonticola dominated the diatom assemblages at both 

 sites sampled in May (Table 5) . This is a cool-season, but clean 



