THE STREAM ENVIRONMENT 177 



of the Rocky Mountains and the Northern Great Plains (McWhorter, 

 Skogerboe, and Skogerboe, 1975). 



The ecological impacts on aquatic ecosystems of mining and 

 processing activities differ in many ways in the West from those in 

 mining regions of the eastern states. Yet, although there is a plethora 

 of literature documenting the effects of mining on aquatic biota in 

 the eastern United States, there are relatively few data on problems 

 associated with mining and resulting effects on aquatic organisms in 

 the West. 



A year-round study was conducted on a Colorado stream that 

 receives drainage from a strip coal mine. The objectives were (1) to 

 compare macroinvertebrate communities and environmental condi- 

 tions at stream locations differentially affected by mining activities 

 and (2) to contrast the results with those of studies of eastern 

 streams receiving coal-mine drainage. 



METHODS AND SITE DESCRIPTION 



Trout Creek, in the Upper Colorado River Basin of northwestern 

 Colorado (Fig. 1), receives groundwater and surface runoff from a 

 strip coal mine (Edna Mine). The area of the watershed above and 

 including the mine totals approximately 1.1 x 10"* ha; the area of 

 mine spoils (597 ha) is slightly more than 4% of the total watershed 

 area upstream from the mine (McWhorter, Skogerboe, and 

 Skogerboe, 1975). The upper portion of the basin, which lies in 

 Routt National Forest, is well vegetated with aspen and conifers. The 

 middle portion of the watershed is a mixture of forests and farmland. 

 Lower reaches are more xeric, with sagebrush and other shrubs and 

 grasses predominating. Agricultural practices (primarily grazing) 

 variously affect middle and especially lower portions of the basin. At 

 elevations ranging from 2160 to 2100 m, the stream is bordered on 

 the east by the Edna Mine. Trout Creek progressively flows past 

 spoils from mining about 30 years ago, spoils 20 to 30 years old, and 

 an area of current mining activity. 



Sampling stations on Trout Creek were located on rubble riffles 

 above, adjacent to, and below the mine spoils at sites from which 

 water chemistry data had been collected in a previous study 

 (McWhorter, Skogerboe, and Skogerboe, 1975). An additional sam- 

 pling station (TC-1) was established upstream from a mine shaft (see 

 Fig. 1) even though the shaft is horizontal and there was no evidence 

 of seepage entering the stream. 



Macroinvertebrates were sampled monthly from July 1975 

 through June 1976. High water or inclement weather precluded 



