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The discussion of probable hydrologic consequences contained in the Quinn Coal findings document identifies only one possibly significant surface water effect. A worst case analysis indicates that if all the ponds were to discharge at once during a 10-year, 24-hour precipitation event, the net effect on Sand Creek would be to increase the salt concentration by 61%. The existing total dissolved solids concentration in Sand Creek is approximately 100 mg/l, so it would increase to approximately 161 mg/1. This concentration is lower than the predicted concentrations resulting from the Red Canyon Mines, and would tend to dilute those concentrations. (The amount of dilution, however, would be less than if Sand Creek were not disturbed by mining.) Even without dilution, the salt loading from the Red Canyon Mines was not anticipated to be sufficient to limit water use. In the future, however, the salt loading effect may become more significant if large amounts of mine water are discharged from the underground workings at the Tomahawk Mine. Depending upon the amount and quality of the mine water discharged to the surface water system, both mines have the potential for a cumulative increase in total dissolved solids concentrations and may also alter other water quality parameters. When Quinn Coal Company submits an application for underground mining operations, the potential for these effects will be more accurately assessed. Therefore, based upon the above cumulative assessment and the discussion of probable hydrologic consequences contained in this findings document and in the Tomahawk Mine findings document, the Division finds that, with the stipulations included in Sections VI and VII of this document, the proposed Red Canyon Mining operation has been designed to prevent material damage to the hydrologic balance outside the permit area. References Cited Kimball, D.B., M.B. Bisthop, K.E. Kelly, D.G. Bailey, G.W. Quinn, 1982, Hydrology and alluvial valley floor report - Red Canyon Mines, prepared for the Grand Mesa Coal Company by Kaman Tempo, Denver, Colorado 99p. McWhorter, D.B., 1981, Procedures for predictive analysis of selected hydrologic impacts of surface mining, Draft report, U.S.E.P.A., Cincinnati, Ohio. Climatological The sections of the permit application dealing with climatological information and air resources have been reviewed by the Division. Climatological information is presented on page 66 of the application. The air pollution control plan can be found on page 139 of the application. The proposed operation has received final approval for emissions permit No. C-12,480 issued by the Colorado Department of Health for a 400,000 ton per year operation. The permit applies to activity at both the load-out and the mine portals area. -33-