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Review of hydrographs and the above table shoos that floe the past five years has been lower than previously measured. This is Largely due to relatively loner snowmelt runoff during this period. Also affecting flow from the 004 pond is the reduced diameter of the discharge culvert modified on May 29, 1987 (36 inches to 6 inches). Review of Table 15 (Appendix A) shows the water at this site to be a Mgca-S04 type. TDS has consistently increased since 1982 primarily due to a concurrent increase in upgradient mined area and ground water resaturation in the spoils. Also responsible for the increase in TDS in 1987 through 1991 is the tlecr ea sad spring snowmelt runoff for this period as compared to 7984 through 1986. Reduced runoff antl subsequent evaporation during the summer tends to concentrate dissolved solids, resulting in increased TDS over time. Surface Water Site SN-S2-6. This site monitors Cow Camp Creek less than 1/4 mile downstream of the NPDES 004 discharge and an adjacent diversion ditch. Review of a hydrograph consisting of all data from May, 1981 to September, 1991 shows that spring runoff has been lower than normal the last five years. Peak flows at this site have been reduced further by the reduction of discharge culvert diameter in 1987 at the NPDES 004 site discussed earlier. Review of Table 17 (Appendix A) shows that Site b displays a MgCa-S04 type eater. TDS values have increased every year (excepting 1991) as a result of the TDS increases noticed at the NPDES 004 site (caused by spoils eater discharges) and, to a lessor extent, reduced runoff and subsequent evaporation. Surface eater Site SN•52-10. The site was instituted in May, 1987, and monitors Cow tamp Creek at its confluence with Fish Creek. It is monitored May through September on a monthly basis. As was suspected by PCC staff before initiating monitoring, this site flows less often than the upper Cow Camp Creek, Site b. Flow was observed only for the May and June monthly visits, while Site b floes year round. Flow at this site was 38 percent less than that of Site b in May (80 percent less than in June) due to stream channel infiltration and the absence of lateral inflow from tributaries to Cow Camp Creek. water at this site is a MgCaN a-504 type (see Table 17, Appendix A). TDS increases downstream due to the alkaline and saline nature of the soils along Lou Camp Creek in Twen[ymile Park, and due [o the evaporation in several stock reservoirs located on Cow Camp Creek between the two sites. TDS values at Site 10 fluctuate from year to year. 13