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 Teton County near the town of 

 Choteau, Montana (pop. 1,586) . Spring Creek heads about a mile 

 east of Eureka Reservoir at an elevation of 4,100 feet. It then 

 flows southeast through Choteau to where it enters the Teton 

 River near the Freezeout Lake Wildlife Management Area, about 15 

 miles from its source . 



The Spring Creek watershed is located on the boundary of the 

 Northwestern Glaciated Plains Ecoregion and the Montana Valley 

 and Foothill Prairies Ecoregion (Woods et al . 1999). The surface 

 geology consists of Cretaceous, shales of the Colorado Group 

 overlain in places by Quaternary gravel deposits (Renfro and 

 Feray 1972) . Vegetation is mixed grassland (USDA 1976) . 



Periphyton samples were collected at two sites on August 1, 

 2000 (Map 1, Table 1) . The upper site (S-2) is at an unnamed 

 road crossing downstream from U.S. Highway 89. The lower site 

 (S-3) is located upstream from Choteau. The two sites bracket 

 a three-mile reach of Spring Creek that runs east of and parallel 

 to U.S. Highway 89. Elevation at the sampling sites is about 

 4,000 feet above mean sea level. 



Land use in the Spring Creek watershed is mostly livestock 

 and wildlife grazing with some residential and commercial 

 development. Spring Creek is classified B-2 in the Montana 

 Surface Water Quality Standards. 



