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constant source of water in these drainage systems has encouraged the growth of vegetation. <br />This has resulted in the channels becoming more erosionally stable but more incised. <br />Surface water monitoring practices and frequencies are described within the permit application. <br />Also see Findings Section B, Item II E, of this document for a summary of surface and ground <br />water monitoring practices to which Western Fuels-Colorado has committed. <br />Ground Water <br />The New Horizon Mines lie in a ground water basin defined by the Nucla Syncline. This broad <br />northwest trending syncline is recharged along the Uncompahgre uplift to the northeast and <br />discharges southwest toward the major rivers flowing through the area. <br />Near surface ground water in the Nucla area is partially recharged by irrigation return flow <br />through Quaternary aeolian and alluvial deposits. The lower Dakota and underlying Morrison <br />Formations are regional aquifers, although water from the Dakota Formation is not heavily <br />utilized due to its high salinity. The Morrison Formation water is widely used for stock and <br />domestic wells. <br />Very little hydrologic documentation is available regarding the alluvium found along the small <br />tributaries draining the area. Peabody drilled one well in the alluvium of Calamity Draw in <br />mid-1986. The well appears to have been completed in a clay lens. The alluvial water table <br />fluctuates seasonally within 5 to 10 feet of the surface with highest water levels in August and <br />lowest water levels in January. Recharge is primarily derived from irrigation return flow and <br />secondarily from flow in Calamity Draw. Transmissivity varies from 6.6 to 10.1 ft2/day. The <br />hydraulic conductivity varies from 0.4 to 0.6 ft/day. The water is characterized as a saline, hard, <br />neutral pH, calcium sulfate water with average TDS of 3291 mg/l. <br />The aquifer overlying the coals in the upper strata of the Dakota Sandstone is unconfined and <br />flows generally toward the southwest. Water levels fluctuate between 3 and 23 feet below the <br />ground surface. Highest levels (closest to the surface) of this water table occur between June and <br />August, as a result of irrigation, and lowest levels between December and March. Two wells <br />south of Calamity Draw (GW-N31 and GW-N32 on the monitoring stations map) have exhibited <br />limited water level fluctuations since their construction in mid-1986. <br />The Upper Dakota aquifer is predominantly recharged by return flow from the West Lateral <br />Irrigation Ditch. Some recharge is probably derived from infiltration of precipitation and <br />subsurface ground water flow. The transmissivity of the overburden (Upper Dakota aquifer) <br />varies from 3 to 53 ft2/day, averaging 13.3 ft2/day. The McWhorter analysis of pit inflow <br />conservatively estimated that the hydraulic conductivity of the overburden was 0.61 ft/day. <br />Hydraulic conductivity calculations from field tests of the overburden showed a range of 0.39 to <br />1.05 ft/day, indicating moderate permeability. <br />The water found in the overburden is characterized as very hard, saline, calcium/magnesium <br />sulfate water with neutral pH. TDS levels vary from 1494-10074 mg/1 and average 4613 mg/1. <br />Sulfate concentrations are very high, varying from 875 mg/1 to 6872 mg/1 and averaging 3176 <br />mg/1. In some of the overburden wells, sulfate, TDS, manganese and fluoride exceed <br />12