Project Area and Sampling Sites 



The project area is located within subregion 17g of the Middle Rockies Ecoregion in 

 Gallatin County, Montana. This is a partially glaciated subregion of carbonate-rich, mostly 

 forested mountains and hills with some lakes and springs (Woods et al. 1999). Bedrock and 

 surface material is composed mostly of faulted and folded Mesozoic-Paleozoic sedimentary 

 rocks, including limestone, and Quaternary drift and colluvium. Vegetation is mainly mixed 

 conifer forest of Douglas-fir and subalpine fir, with alpine tundra on the highest peaks. The main 

 land uses are logging, mining, recreation, Uvestock grazing, and wildlife habitat. 



Periphyton samples were collected at two sites on Beaver Creek (Map 1 and Table 1). 

 Beaver Creek is in the Madison River hydrologic unit (USGS HUC 1 0020007). The Madison 

 River, along with the Jefferson and Gallatin Rivers, are the three main tributaries of the Missouri 

 River. Beaver Creek is classified B-1 in the Montana Surface Water Quality Standards. 



Methods 



Periphyton samples were collected following standard operating procedures of the 

 MDEQ Planning, Prevention, and Assistance Division. Using appropriate tools, microalgae 

 were scraped, brushed, or sucked fi-om natural substrates in proportion to the importance of those 

 substrates at each 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 (IKI) solution. 



The samples were examined to estimate the relative abundance 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 Smith (1950), Prescott (1962, 1978), John et al. (2002), 

 and Wehr and Sheath (2003). These books also served as references on the ecology of the soft 

 algae, along with Palmer (1969, 1977). 



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