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groundwater inflow from the alluvial aquifer (or to minor unmonitored surface <br />sources from the West side of the creek, opposite the mine.) The surface sources <br />from within the permit azea also decrease significantly during the summer, causing <br />the calculated inflow from groundwater sources between the upstream and <br />downstream points to increase to 26%. Since this water is currently high in <br />TDS from contact with the spoils, the result is that the highest concentrationsof TDS in <br />Trout Creek occur in the late summer, when dilution is at a minimum. <br />The content of TDS in groundwater predicted in the original permit has been <br />exceeded at both the West Ridge and Moffat Areas. The predicted TDS content in <br />post-mining groundwaterin the West Ridge azeas was 2828 mg/1. Analyses of water <br />from well WR-1, within the West Ridge spoils, show concentrations ranging from <br />3000 to > 4000 mg/1 TDS. The predicted TDS content for groundwaterin the Moffat <br />Area was 2290 mg/1. Analysis of water from spoils springs sites show post-mining <br />TDS concentrations ranging from 3800 mg/I to >4500 mg/1. <br />Even still, the predicted high concentrations for Trout Creek at the downstream <br />monitoring site aze not exceeded through most of the monitoring season. The <br />predicted maximum high concentrationwas 1090 mg/l. This concentrationhas been <br />exceeded twice during the month of April, when spring runoff flows have begun at <br />the mine, but before the runoff increases significantly from sources upstream from <br />the mine. Predicted concentrations at other times of the yeaz have not been exceeded <br />in the last two yeazs. For example, the predicted low-flow TDS was 635 mg/1 for the <br />late summer season. This concentration was exceeded in 1993 (measured value over <br />1000 mg/I) and reached in 1994 (measured value about 640 mg/I), but the last two <br />summer, the TDS measured values reached only 400 mgll maximum. It must be that <br />the groundwatercontributionfrornthe Edna Mine to Trout Creek is actually less than <br />anticipated, since the overall effect on the chemistry of Trout Creek has been less than <br />predicted. <br />A calculation using a concentration of 400 mg/I for water at the downstream <br />monitoring site and a flow rate of ] 5 ft3/sec. yield a total of 5,896 tons of dissolved <br />salt per yeaz in Trout Creek. Assuming that perhaps 25% of that is already in <br />the stream before it reaches the Edna Mine, it is calculated that 5000 tons or less per <br />yeaz of salt is contributed to the drainage basin by the Edna Mine. <br />III. Topsoil <br />A. The Division previously granted a variance from topsoil removal in accordance with <br />Rule 4.06.2(2)(a) for steep slope azeas of the eastern portion of the Moffat Area. <br />Topsoil was redistributed on those azeas. Some portions of the West Ridge Area <br />Edna Mine Z2 Permit Renewal No. 3 <br />