2008-04-15_REVISION - M1980244 (309)

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• upper reaches are affected by discharges from the City of Cripple Creek's waste water treatment plant. Cripple Creek has use classifications for recreation (Class E), agriculture, and as a Class 2 cold water aquatic stream. Standards exist for pH, dissolved oxygen, E. Coli, minor anions including chlorine, sulfide, and cyanide, nutrients of ammonia and nitrite, as well as some trace metals (arsenic, boron, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, selenium, silver and zinc). Water quality measurements for the Cripple Creek stations have been compiled and are presented in Appendix 2, Volume II of this document. The water quality monitoring in Cripple Creek shows a sodium-calcium sulfate-bicarbonate- chloride system at the three upstream stations, and a calcium sulfate matrix at the downstream station (CC-04). The pH ranges from 7.8 to 8.0 from upstream to downstream. Average sulfate concentrations increase from 126 mg/L to 190 mg/L downstream. Average nitrate levels drop from 11.3 mg/L to 7.3 mg/L downstream. Sulfate levels may be attributable to historic mining operations, and nitrate concentrations are due to influences from the waste water treatment plant, which are diluted with increased flows downstream. • Grassy Creek Flows in Grassy Creek are ephemeral. CC&V monitors three stations on Grassy Creek. The oldest station was established in 1996 and the other two stations were established in 1997. The flow data indicate intermittent flow with a distinct relationship to precipitation. 4.6.2 Ground Water Shallow ground water in the project area occurs at some locations in alluvial aquifers associated with the surficial drainages or in shallow, fractured bedrock. Deeper ground water in the District occurs in two distinct hydrologic zones that are strongly controlled by the geologic setting: the volcanic diatreme and the surrounding granitic rocks. A description of the general geology of the region, and specifically the geology beneath project areas was previously provided in Section 4.4. The following summarizes the ground water system with a complete description of the ground water system contained in Appendix 2, Volume II of this document. • Cripple Creek & Victor Gold Mining Company Cresson Project Mine Life Extension 4-11