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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. 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 April 29, 2004 and were performed according to the <br />procedures outlined in EPA-821-R-02-012 (2002). The Daphnia magna test was conducted <br />over 48 hours. The test was run with exposure concentrations of 100%, 50%, 25%, 12.5%, and <br />1.9% effluent. Moderately hard laboratory reconstituted freshwater was used for the control <br />and for the dilutions. <br />Data Analysis <br />Data from the tests were analyzed on a Pentium personal computer. Where applicable, <br />LC50's were calculated using EPA's TOXDATMultl-Method Program according to the binomial, <br />probit, or moving average methods. Statistically significant differences beiween control and <br />exposed organisms were determined using the TOXSTAT software developed atthe University <br />of Wyoming. <br />RESULTS <br />The results of the tests are summarized in Appendix 2. An LC50 of 86.36% was created <br />in the Daphnia magna test. Survival was 40% in the 100% effluent and ranged from 60 -100% <br />in the remaining effluent concentrations. Survival was 100% in the control. <br />DISCUSSION <br />The D. magna test fails due to the creation of an LC50 concentration of 86.36%. <br />Possible reasons for this mortality could be the high alkalinity, high conductivity or the presence <br />of a large amount of total dissolved solids (TDS). A second accelerated test is the next step in <br />fulfilling permit requirements for the D. magna species. <br />REFERENCES <br />EPA-821-R-02-012. 2002. Methods for Measuring the Acute Toxicity of Effluents and <br />Receiving Waters to Freshwater and Marine Organisms (fifth edition).. 266 pp. <br />APHA/AWWANVEF. 1998. Standard Methods for the Examination of Water and Wastewater. <br />20th Edition. American Public Health Association. <br />Hach Company. 2002. Hach Water Analysis Handbook. 4th Edition. Hach Company, <br />Loveland, Colorado. 1260 pp. <br />The SeaCrest Group 3 <br />