Project Area and Sampling Sites 



The project area is located in northern Park County in south central Montana. The 

 Shields River is a tributary of the Yellowstone River. It heads in the Bridgcr and Crazy 

 Mountains (maximum elevation 1 1,214 feet) and flows west and south for about 40 miles to 

 where it enters the Yellowstone River a few miles downstream from the city of Livingston. 

 The headwaters of the Shields River are in the Middle Rockies Ecoregion, while some tributaries 

 and the mainstem of the Shields River flow mostly through the Northwestern Great Plains 

 Ecoregion (USEPA 2000). All of the sampHng sites are in the Northwestern Great Plains 

 Ecoregion. 



Periphyton samples were collected at 4 sites (Table 1). Elevations at the sampling sites 

 range from about 5,400 feet above mean sea level at the upper site (Coal Camp Road) to about 

 4,400 feet at the lower site near the mouth. The surface geology of the watershed consists of a 

 matrix of Paleocene continental deposits with granitic intrusives of Tertiary age (Renfro and 

 Feray 1972). Vegetation in the study area is alpine tundra at the highest elevations, mixed 

 conifer forest at intermediate elevations, and mixed grassland along the lower Shields River 

 (USDA 1976). Land use is primarily livestock grazing and hay production, with logging and 

 recreation in the headwaters. The Shields River is classified B-1 in the Montana Surface Water 

 Quality Standards. 



Methods 



Two of the periphyton samples were collected following standard operating procedures 

 of the MDEQ Planning, Prevention, and Assistance Division. Using appropriate tools, micro- 

 algae were scraped, brushed, or sucked from natural substrates in proportion to the importance of 

 those substrates at each study site. Macro-algae were then picked by hand in proportion to their 

 abundance at the site. All collections of micro-algae and macro-algae were pooled into a 

 common container and preserved with Lugol's (IKI) solution. Four of the samples were grab 

 samples of conspicuous macro-algae and were collected for the purpose of identification only. 



