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Calamity Draw in mid-1986. The well appears to have been completed in a clay lens. The alluvial <br /> water table fluctuates seasonally within 5 to 10 feet of the surface with highest water levels in <br /> August and lowest water levels in January. Recharge is primarily derived from irrigation return <br /> flow and secondarily from flow in Calamity Draw. Transmissivity varies from 6.6 to 10.1 ft2/day. <br /> The hydraulic conductivity varies from 0.4 to 0.6 ft/day. The water is characterized as a saline, <br /> hard, neutral pH, calcium sulfate water with average TDS of 3291 mg/1. <br /> The aquifer overlying the coals in the upper strata of the Dakota Sandstone is unconfined and flows <br /> generally toward the southwest. Water levels fluctuate between 3 and 23 feet below the ground <br /> surface. Highest levels (closest to the surface) of this water table occur between June and August, <br /> as a result of irrigation, and lowest levels between December and March. Two wells south of <br /> Calamity Draw (GW-N31 and GW-N32 on permit Map 2.04.7-1A) exhibited limited water level <br /> 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 groundwater flow. The transmissivity of the overburden(Upper Dakota aquifer)varies <br /> from 3 to 53 ft2/day, averaging 13.3 ft2/day. The McWhorter analysis of pit inflow conservatively <br /> estimated that the hydraulic conductivity of the overburden was 0.61 ft/day. Hydraulic <br /> conductivity calculations from field tests of the overburden showed a range of 0.39 to 1.05 ft/day, <br /> 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 /> recommended standards for livestock drinking water. In addition, concentrations of manganese <br /> and fluoride exceed the agricultural use standards in some wells. <br /> The Dakota coal has been described as an aquifer. Wells completed in the Dakota show water <br /> level fluctuations of 1.3 to 14.6 feet. The water table exhibits seasonal fluctuations with high water <br /> levels in late fall. The aquifer is recharged from the east north-east and discharges to the west and <br /> along Calamity Draw. The transmissivity varies from 0.92 to 6.0 ft2/day, based on hydraulic <br /> conductivity values of 0.04 to 0.34 ft/day (average values of 0.19 ft/day),reflecting moderate flow <br /> capabilities. <br /> The water quality of the Dakota coal is unacceptable for most uses. The saline, sulfate-based water <br /> has TDS levels varying from 1050-4444 mg/1, averaging 2822 mg/1. Three wells exhibit two <br /> distinct geochemical characteristics. Two wells have calcium/magnesium sulfate water with the <br /> pH averaging 5.4. One well, 17-P 1, is an alkaline sodium sulfate water with the pH averaging 9.2. <br /> Iron, manganese, aluminum, fluoride and pH levels exceed recommended water quality criteria <br /> for agricultural use, and concentrations of aluminum and fluoride exceed recommended water <br /> quality criteria for livestock. <br /> The aquifer underlying the coal is identified as the underburden aquifer. The wells in the <br /> underburden have been completed 17 to 64 feet below the coal, and samples are representative of <br /> 14 <br />