Some algae, such as the filamentous greens, are conspicuous 

 and their excessive growth may be aesthetically displeasing, 

 deplete dissolved oxygen, interfere with fishing and fish 

 spawning, clog water filters and irrigation intakes, create 

 tastes and odors in drinking water, and cause other problems. 



PROJECT AREA AND SAMPLING SITES 



The project area is located in northern Park County in 

 southcentral Montana. The Shields River heads in the Crazy 

 Mountains (maximum elevation 11,214 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 of North America; the lower reaches of this 

 stream pass through the Montana Valley and Foothill Prairies 

 Ecoregion (Woods et al . 1999). 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 is alpine tundra at the highest elevations, mixed 

 conifer forest at intermediate elevations, and mixed grassland at 

 lower elevations (USDA 1976) . 



Periphyton samples were collected at two sites on September 

 19, 2000 (Maps 1 and 2, Table 1) . The upper site (Station 1) was 

 located below the National Forest boundary at an elevation of 

 5,700 feet (Map 1). The lower site (Station 2) was located about 

 2 miles downstream from the town of Wilsall at an elevation of 

 4,920 feet (Map 2). The Shields River is classified B-1 in the 

 Montana Surface Water Quality Standards. 



