Periphyton samples were collected at one site on each stream 

 in early August 2000 (Table 1) . The Antelope Creek site (Map 1) 

 is located just above the mouth of the stream at an elevation of 

 about 4,900 feet. The Potter Creek site (Map 2) is located just 

 north of the Wilsall Airport at an elevation of about 5,100 feet. 



METHODS 



Periphyton samples were collected by Patrick Newby of the 

 MDEQ Monitoring and Data Management Bureau following standard 

 operating procedures of the MDEQ Planning, Prevention, and 

 Assistance Division. 



Using appropriate tools, microalgae were scraped, brushed, 

 or sucked from natural substrates in proportion to the rank of 

 those substrates at the study site. Macroalgae were picked by 

 hand in proportion to their abundance at the site. All 

 collections of microalgae and macroalgae were pooled into a 

 common container and preserved with Lugol ' s solution. 



The samples were examined to estimate the relative abundance 

 of cells and rank by biovolume of diatoms and genera of soft 

 (non-diatom) algae according to the method described in Bahls 

 (1993) . Soft algae were identified using Dillard (1999) , 

 Prescott (1978), Smith (1950), and Whitford and Schumacher 

 (1984) . These books also served as references on the ecology of 

 the soft algae, along with Palmer (1977) . 



After the identification of soft algae, the raw periphyton 

 samples were cleaned of organic matter using sulfuric acid, and 

 permanent diatom slides were prepared using Naphrax, a high 

 refractive index mounting medium, following Standard Methods for 

 the Examination of Water and Wastewater (APHA 1998) . Between 413 

 and 428 diatom cells (826 to 856 valves) were counted at random 



