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. Cottonwood Creek and Rock Creek head in 

 the Crazy Mountains (maximum elevation 11,214 feet) and flow 

 southwesterly for about 15 miles to where they enter the Shields 

 River near the town of Clyde Park (pop. 3 02) . 



The headwaters of Cottonwood Creek and Rock Creek are in the 

 Middle Rockies Ecoregion of North America; the lower reaches of 

 these streams pass through the Montana Valley and Foothill 

 Prairies Ecoregion (Woods et al . 1999). The surface geology of 

 the watersheds 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 Cottonwood 

 Creek in late July and early August 2000 (Maps 1 and 2, Table 1) . 

 The sample collected at the upper site (Map 1, Station 1) 

 contained no algae and could not be used for bioassessment . The 

 lower site (Map 2, Station 2) was located at an elevation of 

 5,500 feet about 7 miles upstream from the mouth of Cottonwood 

 Creek at Clyde Park. 



Periphyton samples were collected at two sites on Rock Creek 

 on July 28, 2000 (Map 2, Table 1) . The upper site (Station 1) 



