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1980CY = 0.990 cfs <br />Discharges measured at this site ere also affected by the pumping of water from this pond <br />for the truck wash system. This pumping began on September 18, 1984. In addition, spring <br />runoff floes are affected primarily by the snowpack for that winter and not what the total <br />precipitation was far that whole water year. In other words, a normal water year (in <br />regards to total precipitation) may have below normal spring runoff if the snowpack for <br />that winter was below normal. <br />Review of Table 15 (Appendix A) shows this water to be a M9Ca-504 type. TDS values at <br />this site have remained relatively stable since 1981, indicating that the water quality of <br />spoils discharges into this pond have also stabilized. <br />For NPDES 002, TDS and sulfate values have been plotted on one graph, copper and Lead <br />values on a second and sulfides on a third (Appendix H). Review of the TDS/sulfate graph <br />show the seasonal variability as noted on the previous graphs in this Annual Hydrology <br />Report. No long-term trend is apparent. The copper/lead end sulfide graphs also shows no <br />• <br />discernible long-term trend. The decreasing lead values noted after August 31, 1990 are a • <br />result of a lowered detection limit. <br />Grassy Creek Drainace. Three monitoring sites lie within the Grassy Creek drainage: <br />Surface Yater Site SW-S2-1, located upstream on Grassy Creek; NPDES Discharge Point 003, <br />also known as [he Shop Reservoir or the Northwest Impoundment, located just north of the <br />mine shop area; end Surface Water Site SW-S2-2, located approximately 0.1 mile downstream <br />of where NPDES 003 discharges into Grassy Creek. <br />Surface Water Site 5Y-S2.1. This site monitors the upper reaches of Grassy Creek which <br />are undisturbed by mining of the Seneca II Mine. Review of the hydrograph of monthly flow <br />readings shows low runoff in 1992 similar to 1987 to 1991 and significantly less than 1982 <br />through 1986. <br />Review of Table 17 (Appendix A) shows the water at this site to be a CaMg-504HC03 type. <br />Increasing sulfate concentrations and slightly increasing TDS values are most likely due <br />to background conditions in the watershed above this site end the decreased snowmel[ <br />runoff the last six years. <br />J <br />18 <br />