Project Area and Sampling Sites 



The project area is located in McCone County in northeastern Montana. Horse Creek, is a 

 tributary of the Redwater River near Circle (HUC 10060002). Like the Redwater River, Sand 

 Creek and Prairie Elk Creek are south side tributaries of the Missouri River (HUC 10060001). 

 Prairie Elk Creek heads northwest of Circle in central McCone County and flows north to meet 

 the Missouri River just south of Wolf Point. Sand Creek, the next drainage to the east of Prairie 

 Elk Creek, heads north of Circle and enters the Missouri River a few miles downstream. Nelson 

 Creek is a tnbutary of the Big Dry .\nn of Fort Peck Reservoir (HUC 10040104). 



The streams are located in the Northwestern Great Plains and Northwestern Glaciated 

 Plains Ecoregions (Woods et al. 1999). The surface geology of the area consists of coal-bearing 

 sedimentary rocks of the Fort Union Formation and sandstones and shales of the Montana Group 

 (Renfro and Feray 1972). The climate is semiarid and continental, with cold winters and hot, dry 

 summers. Upland vegetation is predominantly mixed grassland steppe (USDA 1976). The main 

 land uses are livestock grazing and dry land farming. 



Periphyton samples were collected at 4 sites on the Redwater River, 3 sites on Horse 

 Creek, 2 sites on Sand Creek, and 1 site each on Nelson Creek and Prairie Elk Creek (Table 1). 

 Elevations at the sampling sites range from about 2,500 feet to 2,000 feet. The streams are 

 classified C-3 in the Montana Surface Water Quality Standards. 



Methods 



Periphyton samples were collected following standard operating procedures of the 

 MDEQ Plarming, 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. 



