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<br />Changes in evapotranspiration and the partitioning of meteoric water into swface <br />and subsurface components by the factors discussed above are expected to be <br />minimal. Therefore, the post-mining water balance is estimated to be virtually <br />unchanged from that which now exists. <br />Water Quality Effects <br />The primary impact from mining on surface water quality at the Edna Mine has been <br />identified as potential salt loading of Trout Creek. Increased concentrations of total <br />dissolved solids (TDS) in the stream were expected, based upon mass-balance <br />calculations presented in the application. <br />Groundwater Effects <br />P&M did not mine within the Oak Creek drainage, therefore, the addition of poor <br />quality spoil aquifer discharges to the creek did not occw. Minor amounts of <br />dissolved constituents might have been added to the Oak Creek alluvial aquifer <br />system from surface distwbance at the oftice/loadout azea. However, due to <br />extensive previous mining in this drainage, and the limited amount of surface <br />distwbance, the Edna Mine operations will not significantly impact the aquifer. <br />Monitoring data collected during past permit terms substantiate this conclusion. <br />Monitoring of the alluvial aquifer did not detect significant degradation of the water <br />quality, nor depletion of the aquifer itself. <br />Impacts on Oak Creek aze related to altered timing of flows and water quality <br />resulting from sediment pond discharges. The series of fow sediment ponds <br />constructed below the loadout facilities serve to maintain water quality at <br />distwbances in this drainage. Monitoring data collected during past permit terms <br />support this conclusion. <br />The effects on the Trout Creek watershed are greater. The data and conclusions for <br />the analysis of probable hydrologic consequences have been updated in the Edna <br />permit as addenda specifically addressing TDS and sulfate, the two pazameters most <br />likely to impact Trout Creek and, consequently,the Yampa River Basin. The quality <br />of water is affected by the mining activity. <br />Monitoring at the Edna Mine is accomplished on Trout Creek upstream of the mine, <br />adjacent to the Moffat Area (farthest downstream activity), and downstream of the <br />mine. Key groundwater monitoring sites aze located in the alluvium of Trout Creek <br />upgradient of the West Ridge Area (and therefore upgradient of the influence of <br />permitted activity at the Edna Mine), at three locations on the East side of Trout <br />Creek (the same side of the creek as the mine), and at one location within the spoils <br />at West Ridge. Additional analyses of groundwaterare obtained by monitoring water <br />Edv Mine <br />]0 <br />Permit Renexal No. 3 <br />