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Th~ a Jec~Cr~rt Group <br />An Environmental Services Company <br />August 13, 2004 <br />Mr. Henry Barbe <br />Mountain Coal Company <br />P.O. Box 591 <br />Somerset, CO 81434 <br />Dear Mr. Barbe: <br />Enclosed is the report for the acute tests performed for Mountain Coal Company on the West Elk <br />Mine dischazge site. There was toxicity seen to the Daphnia magna species; therefore, further <br />accelerated testing will be required in order to fulfill permit requirements. <br />As with previous tests for the West Elk mine discharge, a set of three screen tests was performed <br />with this effluent sample. The original sample was diluted to concentrations of 12.5%, 25%, and <br />50% and then complete acute tests were conducted using each of these diluted effluent samples. <br />As can be seen in the results section of the report, all three screen tests failed by producing LC50 <br />concentrations, which were at or below 80.6 %. <br />It can be concluded from these results that high alkalinity is probably the source of toxicity to the <br />Daphnia magna species in this particulaz effluent sample. <br />If you have any questions or concerns, please do not hesitate to contact me at (303) 661-9324. <br />Best regazds, <br />Amy D. de la Chica <br />Senior Scientist <br />Enclosure(s): Report <br />Invoice <br />1341 Cannon Street • Louisville, Colorado 80027 • 303-661-9324 • fax 303-661-9325 <br />