Antelope Creek (Table 5) . Diatoms and green algae have a 

 competitive advantage over nitrogen- fixing cyanobacteria when a 

 waterbody is enriched with nutrients. This may help to explain 

 the absence of blue-green algae in Antelope Creek. 



The siphonaceous chrysophyte Vaucheria dominated the sample 

 from Antelope Creek and the filamentous green alga Enteromorpha 

 was abundant here (Table 5) . Both of these algae are typical of 

 spring- fed streams that have a steady supply of cool water. 



Stigeoclonium was common in the sample from Potter Creek 

 (Table 5) . This genus is a good indicator of nutrient enrichment 

 (Palmer 1977) . Anabaena was one of three nitrogen-fixing 

 cyanobacteria in Potter Creek. Under certain conditions, 

 Anabaena can produce waterblooms that release neurotoxins into 

 the water. These toxins can be lethal to livestock, pets, and 

 wildlife. However, Anabaena was not abundant enough in Potter 

 Creek to pose a problem for livestock producers. 



DIATOMS 



The major diatom species in Antelope Creek and Potter Creek 

 included ones that are both sensitive to and tolerant of organic 

 pollution (Table 6) . Both streams supported relatively lurge 

 percentages of Nitzschia palea, which is a nitrogen heterotroph 

 that is typical of the zone of heavy organic loading (Lowe 1974) . 



Diatom metrics generated from the Antelope Creek periphyton 

 sample indicated good to excellent biological integrity and full 

 support of aquatic life uses (Table 6) . Siltation, disturbance, 

 toxicity, and organic loading were minor problems. Antelope 

 Creek had good biological integrity when compared to biocriteria 

 for both mountain and prairie streams. It shared about half of 

 its diatom flora with Potter Creek (similarity index = 48.50%). 



8 



