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Mid-Continent Resources'Stream Impairment Study 13 <br /> during the low flow period, the bottom substrate had a cohesiveness that did not permit the free <br /> movement of cobble and gravel. Streamside cover was minimal with little vegetation and bank <br /> stability ranked fair with high erosion potential during high flow. <br /> Much like Site 1, the site 5 study reach appeared to be indicative of first order streams within <br /> the region(Cooperrider et al 1986). In June, bottom substrate and embeddedness ranked good with <br /> the large majority of cobble being free of deposition. In September, the embeddedness remained <br /> minimal. However, deposition of sediment was evident. This reach consisted primarily of runs with <br /> few pools or deep riffles. Streamside cover was non-existent and bank stability was conducive to a <br /> highly erosive area. <br /> High flows in June produced moderate turbidity at Site 7. This turbidity was not seen in the <br /> fall. Embeddedness was minimal with 25% of substrate surrounded by fine sediment. The bottom <br /> substrate was primarily boulders and cobble, providing stable habitat during both high and low flow. <br /> Channel alteration was not evident. Dominant vegetation was shrub covering 75% of the south <br /> bank. On the north side, a fair amount of exposed soils were observed with slopes up to 60 degrees. <br /> These have strong erosion potential in high flow or rain/snow events. <br /> Discussion <br /> The primary goal of the stream impairment study was to evaluate the biological integrity of <br /> the surrounding waters with respect to the influence of mining activity in the area. To accurately <br /> address the significance of anthropogenic impacts, it was necessary to characterize the significance <br /> of natural perturbations. <br /> The biological, chemical, and physical data collected during this study indicated that several <br /> factors influence the dynamics of this system. Seasonal factors were part of the controlling <br /> mechanism. One of the biggest influences throughout the basin was sedimentation, particularly <br /> during the spring. Along Coal Creek, for example, streamside vegetation was largely nonexistent. <br /> Erosion potential appeared to remain high year round. Macroinvertebrate communities in the reach <br /> near Site 6 appeared to be stable throughout the year but were largely comprised of sediment and <br /> moderately tolerant species. Both the biological and physical data from site 6 indicate that the major <br /> perturbation limiting this system was natural erosion within the area. This site was largely out of the <br /> influence of mining activity. <br /> Dutch Creek in its unimpacted state(Site 1)is an erosive system with poor bank stability and <br /> no streamside cover. It appears the shale rock formations in this region are highly susceptible to <br /> erosion. This seems to limit aquatic ecosystem health through sedimentation in the fall and scouring <br /> in the spring. <br /> Dominance of sediment tolerant species was evident at Stations 5 and 7. Station 1 also <br /> The SeaCrest Group <br />