Project Area and Sampling Sites 



The project area is located within the Middle Rockies Ecoregion (USEPA 2000). The 

 Madison River heads in Yellowstone National Park and its watershed occupies a high mountain 

 basin in southwestern Montana. The surface geology of the watershed is complex, consisting 

 mostly of high-grade metaniorphic rocks and rhyolitic volcanic rocks in the uplands and Tertiary 

 basin fill in the Madison River Valley (Renfro and Feray 1972). Climax vegetation consists of 

 alpine tundra at the highest elevations, Douglas-fir and subalpine fir forest at intermediate 

 elevations, and mixed grassland/sagebrush steppe at lower elevations. The main land uses are 

 recreation, logging, ranching, and mining. 



Periphyton samples were collected at 10 sites on 5 tributaries of the Madison River 

 (Table 1). All sites are in USGS HUC 10020007 and are 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 from 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 LugoTs (IKI) 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). Sof\ 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). 



