Project Area and Sampling Sites 



The project area is located in north central Montana in Teton County north of Great Falls. 

 Lake Creek is a tributary of Benton Lake in Benton Lake National Wildlife Refuge. Lake Creek 

 heads on the Teton Ridge near Power, Montana and then flows southeasterly into Benton Lake. 

 Although included in the Upper Missouri-Dearborn HUC (10030102), Benton Lake has no 

 surface outlet to the Missouri River. The Lake Creek-Benton Lake watershed is entirely within 

 the Northwestern Glaciated Plains Ecoregion (Woods et al. 1999). 



Periphyton samples were collected at two sites on Lake Creek (Table 1). Both 

 sampling sites are at an elevation of about 3,600 feet above mean sea level. Vegetation in the 

 study area is mixed grassland (USD A 1976). Land use is primarily dryland farming, livestock 

 grazing, and waterfowl production in Benton Lake. Lake Creek is classified B-3 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 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 ( 1 969, 1 977). 



