Some measures of the benthic macroinvertebrate communities of insects that were found in Haggarty Creek, which is polluted by effluent from an abandoned copper mine, and Big Sandstone Creek, which is not polluted (Wyoming), were studied in each of two seasons: summer and fall of 2001 and 2002. This was done by randomly collecting samples of benthic macroinvertebrates using both a Surber sampler (4 replicates) and a D-net sampler (also 4 replicates) at each of 10 sites; 5 per creek. Environmental data on several physical and chemical variables were also recorded (environmental data). Some bio-indices, such as the Shannon index, the number of Ephemeroptera, Plecoptera, and Tricoptera taxa, and the Hilsenhoff Biotic Index, were obtained (bio-data). These bio-data, as well as the environmental data, were statistically analyzed using a t-test as well as a one-way analysis of variance. Results indicated that some differences in bio-indices of aquatic insect communities were observed among different sites in a creek, between the two creeks overall, and in different seasons and years. Some of these differences definitely resulted result from the impact of pollution from the copper mine at the upper basin of the Haggarty Creek. Others, however, reflected changes in the insect portion of benthic macroinvertebrate communities due to the progression of seasonal development and emergence of various taxa.