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Based on the observations made durin~his inspection, there does not appear to b~n identifiable point source for the <br />pollution other than that possibly caused by the pre-law abandoned mines in Rush Basin. Since the jurisdiction of the <br />Division's Minerals Regulatory Program is limited to active illegal or permitted mining operations, pursuit of an enforcement <br />action is not possible at this time since no active mining or prospecting was observed. However, since close inspection of <br />Rush Basin itself was not possible during this inspection, the Division will attempt to conduct afollow-up inspection of the <br />uppermost portion of the watershed during Late July or August, 2001 to check for passible illegal mining or prospecting <br />activities. <br />Although the apparent rapid appearance of the precipitate in late August and September may appear at first glance to be <br />associated with a specific incident such as a mine spill, the problem may to a large extent be more seasonal in nature. <br />High flows during spring runoff probably Flush out the previous years' accumulation of light-gray precipitate that, as field <br />observations indicate, only loosely adheres to the rocks forming the channel bottom. The precipitate may begin to re-form <br />after spring runoff ends and acidity in the upper (Rush Basin) portion of the river increases during late summer and fall <br />due to a reversal in relative concentration of clean snowmelt water to mineral-laden ground water seepage and mine water <br />discharge. <br />In the more mineralized upper portion of the watershed, a seasonal increase in acidity would tend to mobilize various <br />metals into solution, and the resulting mineral-laden runoff would be transported rapidly downstream due to the steeper <br />channel gradient occurring near the headwaters. However, the subsequent reduction in channel gradient further <br />downstream and the gradual reduction in acidity resulting from the steady infusion of clean water from tributary channels <br />within the middle and lower portions of the watershed may result in fairly rapid precipitation of mineral compounds. This <br />effect may be enhanced by the presence of several active beaver ponds along the river that act as stilling pools. Another <br />factor that may contribute to rapid formation of precipitate is the presence of limestone deposits within the watershed <br />(Dolores formation outcrops) that may serve to further reduce acidity in the runoff. Also, the fairly large number of small <br />waterfalls along the middle and lower portions of the channel may enhance precipitation by adding oxygen to the runoff. <br />As a means to identify possible solutions to the problem, the Division's Inactive Mine Program (IMP) may be able to <br />address problems associated with non-point source pollution associated with abandoned or inactive pre-law mining <br />operations. The IMP program has in recent years been working with other agencies and stakeholders to address water <br />quality problems in the upper Animas River watershed, and might possiby be in a position to look into water quality <br />problems in the East Mancos River watershed as well. The IMP program may only have limited funds to work with and <br />therefore have to prioritize reclamation/remediation projects on a statewide basis, but it may still be worthwhile to contact <br />them. The program supervisor is Dave Bucknam, 303-866-3783, and the Senior Specialist is Jim McArdle, 303-866-3789. I <br />will provide IMP with a copy of this report, the OS/04/1988 USFS report, and discuss the problem with them over the phone <br />in the near future. If the IMP program staff are unable to look into the problem, they may be able to identify other <br />agencies such as the Colorado Department of Public Health and Environment (CDPHE) -Water Quality Control Division or <br />the U.S. EPA that may be in a better position to address the problem. <br />CC's: Craig Liukko, Red Arrow Gold Corporation, P.O. Box 531, Mancos, CO 81328 <br />Jack Julian, ]B) Ltd., 3991 Stampede Ave., Castle Rock, CO 80104 <br />Wesley Potts, Potco Milling and Mining, 8115 County Road 41, Mancos, CO 81328 <br />Jim McArdle, Division of Minerals and Geology, 1313 Sherman Street, Room 215, Denver, CO 80203 <br />Sarah Johnson, CDPHE, Water Quality Control Division, 4300 Cherry Creek Dr. South, Denver, CO 80246-1530 <br />I & E Contact Address <br />NAME: David L. Yoder <br />OPERATOR: M-E/Yoder Engineers. Inc. <br />STREET: P.O. Box 5740 <br />C1lY/Sl-ATE/ZIP: Avon• C() 816?0 <br />cc: ^ CE <br />t~ BS <br />^ HW <br />^ HMWMD (CH) <br />^ SE <br />L9'WQCD (CH) <br />OTHER see aGuv° <br /> <br />