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In summary, probable hydrologic consequences to the ground water regime will be minor. Localized effects to the hydrologic system wilt include: 1) the draw down of ground water, due to pit dewatering, for a few hundred to perhaps 1,000 feet from the pit; 2) the establishment of a relatively unconfined aquifer of poor quality in the backfilled pits; 3) the probable dewatering of three to five springs in the permit area, two of which are used for stock watering purposes; 4) possibly diminished quantity and quality of water in the Temple Well no. 1; and 5) the possible increase in water and decrease in quality of alluvial water in Hubberson Gulch and its unnamed tributary along the access road, due to infiltration of spoils discharge. Altogether, these impacts are not projected to pose a serious or significant threat to the prevailing ground water system in the area. Surface Water Effects All runoff from the disturbed areas at the mine site during the permit term will be diverted to Sediment Pond 006 prior to release to an unnamed tributary, Hubberson Gulch and eventually Dry Creek. Effects of mining on this water will involve changes in quantity and quality. The mining and reclamation activities will act to change stream channel geomorphologies. Drainage densities and channel frequencies will be reduced, however, Peabody has designed and located post-mining drainage channels to minimize the erosive results of the lowered frequencies. During mining operations and until adequate vegetation is established runoff and erosion rates within the disturbed area will be higher than pre-mining rates. The applicant calculated runoff and erosion/sediment yield rates from disturbed areas when designing Sediment Pond 006 (see Section XXI). Sediment leaving the site will be controlled by effluent limits placed upon the discharge at Pond 006 by Colorado Department of Health as part of the applicant's NPDES permit. Baseline fl ows in Hubberson Gulch exhibit TSS levels from 5 mg/1 to 606 mg/1 with an average of 100 mgl. The total suspended solids increase to Hubberson Gulch is expected to be minimal from mining. Once vegetation is successfully established, the erosion rates are expected to return to the pre-mining level of approximately 140 tons/mil/yr. Sediment Pond 006 will act to control flood flows from the disturbed area. The pond will regulate flood discharges minimizing the impact of the floods. The pond is not expected to significantly reduce the quantity of runoff water available in Dry Creek. The mine area makes up only a small portion of the Dry Creek watershed (0.9%). Surface water quality will be affected by mining. Runoff from disturbed areas will exhibit increases in total dissolved solids. Baseline water quality is of a calcium-magnesium sulfate type. Magnesium and sulfate levels may show an increase in disturbed area runoff, however, these parameters are elevated in baseline waters and the water type will not undergo a change. TDS levels in Hubberson Gulch range between 385 mg/1 and 1632.2 mg/1. -35-