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<br />=. <br />Enviro-Chem Analytical, Inc. <br />685 West Gunnison Avenue, Suite 108 <br />Grand Junction, CO 81505 <br />Outfall 017 <br />2 Species <br />Acute Toxicity Testing <br />West Elk Mine -October 2007 <br />Study Summary <br />An effluent sample collected from the West Elk Mine Somerset, Colorado was <br />evaluated for the presence of acute toxicity to larval fathead minnows <br />(Pimephales promelas) and Daphnia magna during October 23-27, 2007 <br />Moderately hard reconstituted water (MHW) prepared according to USEPA <br />guidelines was used as the diluent for the toxicity tests on the larval fathead <br />minnows. Hard water, with an alkalinity in the range of 1200 - 1500 mg/L, was <br />used as the diluent for the toxicity tests on the Daphnia magna. <br />The effluent tests met minimum control organism performance requirements <br />defined by the USEPA. <br />The table below summarizes the results of the effluent tests. <br /> <br />Test Endpoint Fathead Minnow <br />(% Effluent) Daphnia magna <br />(% Effluent) <br />LC50 >100 >100 <br />Organisms were purchased from Aquatic Biosystems located in Fort Collins, <br />Colorado. All reference toxicity test for both species were performed by them and <br />met minimum performance requirements defined by the USEPA and produces <br />IC25 values within the expected ranges. Organisms were of acceptable quality <br />and proper age upon arrival and beginning of test. The Daphnia magna were <br />cultured and brought up in hard water with an alkalinity between 1200-1500 <br />mg/L. For the purposes of toxicity testing, only neonates which were brooded in <br />the high alkalinity water were used, per the deviance allowed in the permit. <br />1 <br />