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Mountain Coal Company CO-0038776 SeaCrest Number. 399272 <br />A total of twenty organisms at each concentration were used for the daphnia test. <br />Daphnia magna were exposed in 30 ml plastic disposable beakers. Approximately twenty ml of <br />the effluent mixture was added to each beaker. Fathead minnows were exposed in 260 ml plastic <br />cups containing 200 ml of medium. Forty minnows were used at each concentration, following <br />the revised State of Colorado WET testing guidelines. Exposure medium was replaced after each <br />24 hour period and organisms surviving at each concentration were counted and recorded. <br />Routine measurements were made of temperature, pH, and dissolved oxygen in each <br />concentration. <br />The acute tests were started on July 15, 1999 and were performed according to the <br />procedures outlined in Weber (1993). The Daphnia magna test was conducted over 48 hours, <br />the fathead minnow test for 96 hours. The tests were run with exposure concentrations of 100%, <br />759'0, 50%, 25%, and 12.5% effluent. Water used for the control and as the dilution water was <br />moderately-hard laboratory reconstituted freshwater. <br />Data Analysis <br />Data from the tests were analyzed on a Computer Source 386 personal computer. Where <br />applicable, LC50's were calculated using EPA's TOXDATMultt-Method Program according to the <br />binomial, probit, or moving average methods. Statistically significant differences between control <br />and exposed organisms were determined using the TOXSTAT software developed at the <br />University of Wyoming. <br />RESULTS <br />The results of the tests are summarized in Appendix 2. There was some mortality in the <br />Daphnia magna test where survival was 65% in the 100% effluent and ranged from 90-100% in <br />the remaining effluent concentrations. Survival was 95% in the control. No LC50 concentration <br />was produced. <br />The fathead minnow test showed no toxicity, with 100% survival in the 100% effluent and <br />survival ranging from 98-100% in the remaining effluent concentrations. Control survival was <br />100%. <br />DISCUSSION <br />The 013 discharge site passed the whole effluent toxicity test guidelines for both test <br />species. No LC50 was created at any test concentration. <br />The SeaCrest Group- ~ 3 <br />