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+ • -6- • <br />within the Sand Creek watershed. Sand Creek is a tributary of Dirty <br />George Creek which joins Ward Creek to form Tongue Creek. Si rice the Red <br />Canyon mine is also located within the Ward Creek drainage, surface water <br />effects of the two mines may be cumulative. Surface water in the Ward <br />Creek drainge are extensively used for irrigation. <br />The discussion of probably hydrologic consequences contained in the Quinn <br />Coal findings document identifies only one possibly significant surface <br />water effect. A worst case analysis indicates that if all the ponds were <br />to discharge at once during a 10-year, 24-hour precipitation event, the <br />net effect on Sand Creek would be to increase the salt concentration by <br />61~. The existing total dissolved solids concentration in Sand creek is <br />approximately 100 mg/1, so it would increase to approximately 16 mg/l. <br />,This concentration is lower than the predicted concentrations resulting <br />from the Red Canyon mine, and would tend to dilute those concentrations. <br />(The amount of dilution, however, would be less than if Sand (:reek were <br />not disturbed by mining.) Even without dilution, the salt lc ading from <br />the Red Canyon mine was not anticipated to be sufficient to limit water <br />use. <br />In the future, however, the salt loading effect may become more <br />significant if large amounts of mine water are discharged from the <br />underground workings at the Tomahawk mine. Depending upon the amount and <br />quality of the mine water discharged to the surface water system, both <br />mines have the potential for a cumulative increase in total dissolved <br />solids concentrations and may also alter other water quality parameters. <br />When Quinn Coal Company submits an appliation for underground mining <br />operation, the potential for these effects can be more accurately <br />assessed. <br />Therefore, based upon the above cumulative assessment and the discussion <br />of probable hydrologic consequences contained in this findings document <br />and in the Tomahawk Mine finding>document, the Division finds that, with <br />the above stipulations, the proposed Red Canyon Mining operation has been <br />designed to prevent material damage to the hydrologic balance outside the <br />permit area. <br />/ys <br />cc: Jim Pendleton <br />Brian Munson <br />