Project Area and Sampling Sites 



The project area is located within Level IV ecoregion 41c (Western Canadian Rockies), 

 which is an extension of the Canadian Rockies Ecoregion in Flathead County, Montana (Woods 

 et al. 1999). This is a high, rugged, glaciated region that lies west of the Continental Divide and 

 is affected by moist Pacific maritime air masses. The Western Canadian Rockies are underlain 

 by Precambrian rocks, including argillites and quartzites, and mantled by volcanic ash, glacial 

 drift, and colluvium. Soils are thin or absent on upper mountain slopes but become deeper and 

 more developed below. Climax vegetation consists of Douglas-fir, subalpine fir, grand fir, and 

 Engelmann spruce forests, with alpine tundra on the highest peaks. The main land uses are 

 logging, recreation, and wildlife habitat. 



Periphyton samples were collected at two sites on Sullivan Creek and one site on Skyland 

 Creek (Table 1). Sullivan Creek is a west side tributary of Hungry Horse Reservoir in the 

 South Fork Flathead River hydrologic unit (USGS HUC 17010209). Skyland Creek, a tributary 

 of Bear Creek, rises on the west side of the Continental Divide near Marias Pass in the Middle 

 Fork Flathead River hydrologic unit (USGS HUC 17010207). The South Fork, Middle Fork, 

 and North Fork meet to form the Flathead River near West Glacier, Montana. Sullivan Creek 

 and Skyland Creek 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 Lugol's (IKl) 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 



