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variance was granted for the water pump station on Trout Creek, and for the <br />facilities azea along Oak Creek (4.05.18(1)). <br />E. Probable Hydrologic Consequences of Mining <br />Surface Water <br />Information on probablehydrologicconsequencescan be found in Volume 3, Section <br />2.5 and Volume 11, Section 4.6 of the permit application. <br />The hydrologic balance calculations and related information provided in the <br />application allow quantitative estimates to be made in predicting the probable <br />hydrologic consequences of mining on receiving waters. The principle effects of <br />mining will occur in the Trout Creek basin where mining occurs, and aze described <br />below. <br />Water Quantity Effects <br />The quantity of water in the Trout Creek basin will not be increased or decreased as <br />a result of mining. A small change in the partitioning of total nmoffinto surface and <br />subsurface components is the only anticipated effect of mining on the overall water <br />balance. Prior to mining, the ratio was 7 percent surface runoff to 93 percent <br />infiltration. As a result of mining, the predicted ratio changes to 4 percent surface <br />flow and 96 percent subsurface flow. <br />The post-mining landscape of the Moffat Area was regraded and topsoiled to the <br />same general topography as currently exists. It is expected that the mean slope and <br />infiltration capacity of the azea will eventually be very similaz to the pre-mining <br />conditions. An increased potential maximum groundwater retention is expected, but <br />not of a magnitude that will significantly affect the surface water balance over time. <br />Therefore, about the same partitioning into overland runoff and infiltration is <br />expected in the post-mining phase as now exists. <br />Between the time that mining occurred and the time that full revegetation has been <br />accomplished, .evapotranspiration will be reduced resulting in a corresponding <br />increase in subsurface water accumulation. <br />Reclamation activities will eventually establish a plant cover with a water demand <br />similaz to that which existed prior to mining. Possibly the most significantfactor that <br />could substantiallyaffect the post-mining water balance is a change in the effective <br />rooting depth and the total available water-holding capacity of the root zone. Such <br />a change is difficult to accurately predict but no major affects aze anticipated. <br />FA~e Mine 19 Permit R<n<wal No. 7 <br />