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50%, 25%, 12%, and 6% mixtures. Receiving water from Dutch <br /> Creek collected above the discharge point was used as the <br /> source of dilution water and a control . <br /> A total of twenty organisms at each concentration was <br /> used for the tests. Ceriodaphnia were exposed in 30 ml <br /> plastic disposable beakers that could be sealed with a snap- <br /> on cap . Twenty ml of medium was used with five organisms in <br /> each beaker . -'here were four replicates at each <br /> concentration. Fathead minnows were exposed in 260 ml <br /> plastic cups containing 200 ml of medium. Exposures lasted <br /> for 48 hours for the Ceriodaphnia and 96 hours for the fish . <br /> Exposure medium in each chamber was replaced after each <br /> 24 hour period and organisms surviving at each concentration <br /> recorded . Routine measurements were also made of <br /> temperature, pH, and dissolved oxygen in each concentration. <br /> Reference Toxicant Tests <br /> Reference toxicant tests were conducted for the various <br /> test species as a quality control measure to insure the <br /> overall health of the organisms used in the tests. Sodium <br /> dodecyl sulfate was used as the reference toxicant . <br /> Ceriodaphnia were exposed for 48 hours and fathead minnows <br /> for 96 hours. Exposure medium was changed daily and numbers <br /> surviving after each 24 hour period recorded . <br /> Data Analysis <br /> Data from the tests were analyzed on a Compaq Deskpro <br /> personal computer using the TOXSTAT software developed at the <br /> University of Wyoming . Methods utilized included Dunnett 's <br /> Test and Steel 's Many One Rank Test after determination of <br /> data homogeneity using Bartlett 's Test . <br /> RESULTS <br /> Acute Tests <br /> The results of the acute Ceriodaphnia and fathead minnow <br /> tests are summarized in lab data sheets included in Appendix <br /> 2. In the Ceriodaphnia test , there was a 95% survival rate <br /> in the control exposure. The 100% and 50% dilutions had a <br /> survival of 85%. These survival rates were not statistically <br /> significantly different from the control . <br /> The fathead minnow test produced similar results to <br /> those seen in the Ceriodaphnia test . Nineteen of 20 <br /> organisms survived in the 100% effluent after 96 hours. This <br /> was not significantly different from the control survival <br /> which was also 95%. Survival in the other concentrations was <br /> 100%. <br /> DISCUSSION <br />