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WESTERN • • IIIIIIIIIIIIIIIIIII <br />~j FUEIS-lfWl '- . - t' ~---- <br />~ INC. <br />d ~uhwlmn <br />~~ <br />~.f;•slen+ Furir <br />.iiulCkf(uu! Dtc. <br />September 28, 1992 <br />Ms. Anne Ihlenfeldt <br />Colorado Depanment of Health ~- $ ~~ 1 <br />Water Quality Control Division ~ ~r `~ ~ ~ ~~ <br />WOCD-PE-B2 OCR 19199 <br />4300 Cheny Creek Drive South <br />Denver, CO 80222-1530 t)iVIS~U~~ u' <br />n~IrJERNLS 8 3E:;~ •.~i:~ <br />RE: ACUTE BIOMONITORING TESTING OF DESERADO MINE ROOF WATER <br />Dear Ms. Ihlenfeldt: <br />Grab samples of Deserado Mine roof water were collected on August 13, 1992 and delivered to T.H.E. <br />Laboratories in Broomfield, Colorado. The water samples were tested for toxicity to Daphnia magna, <br />Ceriodaphnia and fathead minnows. <br />The LC,~ values for the species were determined as follows: <br />Daphnia Magna 35.4°,6 <br />Ceriodaphnia 33.8°0 <br />Fathead Minnows 71.3% <br />The lab concluded that the high toxicity was probably due to a high conductivity which was over 19000 <br />microhmslcm. An independent analysis of the water sample by ACZ Labs showed conductivity at 25°c of <br />15500 microhms/cm and total dissolved solid of 11,042 mg/I. Copies of the reports submitted by T.H.E. <br />Lab and ACZ Lab are enclosed for your files. <br />WFU believes the high conductivity of the roof water may be contributing to the continued toxicity of the <br />mine effluent. We continue to explore this hypothesis. Ycu will be routinely informed of the progress made <br />in this regard. <br />Sincerely, <br />Murari P. Shrestha, P.E. <br />Assistant Manager of Engineering <br />MS:Igp <br />cc: Don Deardorff <br />Tim Chervick w/o encl. <br />Jett Dubert w/o encl. <br />Tune #iu5 <br />+Ui l'~ban Street <br />f~kes~ood. Colorado;n!'s <br />Trleohone jOj•y&9-ob:b <br />Talecopier jUti98A-Sh- <br />