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Mid-Continent Resources$ Stream Impairment Study 6 <br /> was allowed to equilibrate overnight before the random addition of 20 amphipods per replicate. The <br /> amphipods in the sediment tests were obtained from a commercial supplier and averaged 3 mm in <br /> length. <br /> The tests were aerated and fed on alternate days. The pH, dissolved oxygen and temperature <br /> were recorded daily. Hardness, alkalinity and conductivity of the water were measured on days 0, <br /> 7, 14, 21 and 28. Test chambers were kept at 18-21 °C with a photoperiod of 16h:8h light:dark. <br /> At the end of the test, animals were removed from the sediment and preserved in 70% <br /> ethanol. Adults were counted and observations made on size and fecundity. The amphipods were <br /> dried overnight at 100 °C and weighed. The TOXSTAT data package was used to determine <br /> statistically significant differences between control and exposed organisms. Results were calculated <br /> for measures of toxicity, growth and reproduction. <br /> Benthic macroinvertebrates were collected at each of the seven sites within the study area. <br /> Collections were made with a modified Surber square-foot sampler with 350 micron mesh netting. <br /> Three riffle/run samples and one CPOM sample were taken at each site outlined by the RBP III <br /> protocol in USEPA(1989). Samples were preserved in 70% ethanol and returned to the laboratory <br /> for sorting and enumeration. Identifications were completed to the lowest possible taxonomic level <br /> (Merritt and Cummins 1984; Pennak 1989; Ward 1989) and documented for use in calculating <br /> diversity and community similarity indices. A reference collection was archived for cross-reference <br /> of taxonomic identifications. <br /> Evaluation of habitat quality was preformed to provide support data for impairment analysis. <br /> Habitat assessment procedures followed those outlined in USEPA (1989) and Windell (1989). <br /> Primary observations were made on substrate composition, embeddedness and flow with further data <br /> taken on bank stability , vegetation, and streamside cover. The data were used to calculate the <br /> Biological Condition Index (BCI) (Mangum 1989). <br /> Results <br /> Water Quality Parameters. Analytical results for water chemistry can be found in Appendix <br /> 1. All sites were found to be free of trace metals other than zinc which was found at site 4 during <br /> high flow and in Sites 2, 3, 5 and 6 during low flow. Detectable lead levels were also observed in <br /> Sites 5 and 6 during low flow. All levels were below concentrations which are typically toxic to <br /> aquatic organisms. <br /> Table 1 compares sulfate, alkalinity, and conductivity levels at the sampling stations during <br /> the two flow periods. Sulfate and alkalinity at Sites 2, 3, and 4 were generally 2-3 orders of <br /> magnitude higher than in the control waters. This was true during both high and low flow periods. <br /> Stations 5, 6, and 7 showed similarly low levels of these two parameters during high flow. During <br /> The SeaCrest Group <br />