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To: Oxbow Mining LLC <br />P.O. Box 535 <br />Somerset, CO 81434 <br />Submitted by: Jim Kiger <br />Sample I.D.: 015B discharge <br />Comments: Kept 4C till tested <br />Date: August 1, 2013 <br />No: ECA/OXBOW 14 -WET <br />SAMPLE IDENTIFICATION <br />Date Sampled: July 23 -27, 2013 <br />Date Received: July 23 -27, 2013 <br />Date Tested: July 23 -27, 2013 <br />This letter is in response the the WET study which was done on discharge water from the Oxbow <br />Mining Company, Elk Creek Mine. The discharge location is identified as 015B. This study was <br />for a chronic WET test to be conducted using fathead minnows and Ceriodaphnia dubia <br />(daphnids). <br />The daphnids are very susceptible to high alkalinity. This was evidenced by the lethality of all <br />daphnids within 24 hours when subjected to Oxbow water at a dilution of 100 %. The alkalinity <br />range of this water was 1773 — 1922 mg/L. This alkalinity is substantially higher than the <br />daphnids can tolerate. <br />It is our opinion that the failure of the WET test was due solely to the high alkalinity as is <br />evidenced by the survival of the daphnids in all other dilutions, equal to or greater than the <br />control water. In addition, all other dilutions shows no significant difference on the reproduction <br />statistic when compared to the control group. <br />As this parameter is not one of contamination, as much as a natural occurrence, we would expect <br />the same result with the daphnids if accelerated testing were to commence. Substitution of the <br />daphnids with the Daphnia magna would fix the lethality issue, were the test requirement for <br />acute testing. However, the Daphnia magna are not an acceptable species for use with a chronic <br />test as their maturity rate is outside the 7 -day time period utilized for the chronic test and <br />therefore, it would be impossible to measure reproduction using this species. <br />Results submitted <br />For Enviro -Chem Analytical, Inc. <br />Liese K. Thompson <br />Liese K. Thompson <br />Lab Director <br />