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creek, ephemeral stream flow conditions existed. <br />Data are insufficient to demonstrate whether short term decreases in stream flow <br />are due to initial filling of ponds and resaturation of backfilled spoils. However, it <br />is apparent that any depletion is extremely short- lived. Variability in annual <br />amounts of precipitation supplied to the watershed makes it difficult to assess short <br />term changes; however, long -term changes in flow are expected to be minimal. <br />Three primary impacts on surface water quality were identified: 1) increased <br />erosion and sediment yield; 2) exceedences of applicable water quality standards; <br />and, 3) increased total dissolved solids loading. <br />Increased Erosion and Sediment Yield <br />Sediment yields above pre - mining levels are expected until sufficient vegetation <br />can be established in the watershed. Annual sediment surveys have been <br />conducted on Pond 008. These surveys will allow actual amounts of sediment <br />deposited to be quantified. With continued monitoring, comparisons to estimated <br />design volumes and erosion rates can be made. The pond has ensured compliance <br />with effluent limitations prior to discharge from the mine site. <br />Water Quality Standards <br />Water quality in Fish Creek shows no significant impact associated with previous <br />mining. Data collected at site SW- S2 -13, downstream from previous mining <br />activities, meets receiving stream standards. <br />The pond outfall (NPDES outfall 008) is monitored according to the requirements <br />of the Seneca II Mine NPDES permit (see section B of this document <br />"Monitoring "). <br />Increased Total Dissolved Solids Loading <br />An increase in salinity, as represented by TDS concentrations, is the major surface <br />water impact caused by the Seneca II Mine. The disturbance of sedimentary rocks <br />during the mining and reclamation process exposes more surface area for the <br />solution of minerals and increases the amount of solute available for transport to <br />surface streams. <br />TDS in Bond Creek has risen from 550 mg /1 in 1987 to 1,980 mg /1 in 2010. The <br />operator has suggested that TDS levels in Bond Creek will stabilize now that <br />mining activities have ceased, as has been observed in the portion of the Grassy <br />Creek drainage where mining in the original permit area has ceased. <br />A prediction of TDS loading which could be expected to occur in the Fish Creek <br />17 <br />