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Water from the Trout Creek Sandstone is used to supply the Seneca II Mine facilities. As the supply well is frequently pumped, reliable depth-to-water information is not available from this site. The Trout Creek Sandstone water is a sodium sulfate type with an average TDS concentration in the range of 900 mg/l. The 70 feet of interbedded sandstone, siltstone, coal and shale act as a confining unit which essentially precludes the vertical migration of water between the Trout Creek Sandstone and the Wolf Creek Coal. Consequently no depletion or degradation of water in this aquifer is anticipated as a result of mining operations at the Seneca II Mine. Wolf Creek Coal The Wolf Creek Coal seam is capable of transmitting and storing small amounts of water. Aquifer tests of the unit were performed at the Seneca II-W Mine site, about 5 miles west of Seneca II Mine, in 1980. These tests indicate that the Wolf Creek Coal is a confined aquifer which transmits limited amounts of water. One well was pumped at an average of 1.2 gallons per minute for about 3 '/z hours and produced no observable drawdown at an observation we1120 feet away. Transmissivity values calculated for the Wolf Creek Coal vary between 0.02 ftz per day (0.149 gallons per day per foot) for well 3 WC and 0.001 ftZ per day (0.007 gallons per day per foot) in the two wells tested. Due to the low water yield and transmissivity values, the storativity value of the Wolf Creek Coal is estimated to be about 1 X 10-5. Both transmissivity and storativity appeaz to be quite low due to the highly lenticulaz and discontinuous nature of the Mesaverde Group. It is thought that transmissivity and storativity values will be variable over large areas. Two wells remain that are monitored for water level, S10-WC and S15-WC, both of which are up-gradient of the mining operation. Water in both these wells retained a relatively uniform level throughout the early years of mine life. S10-WC level varied around 79 feet below ground surface (bgs). After 1989, the levels have dropped and appeaz to have stabilized azound 83 feet bgs. S 15-WC levels varied around 80 feet bgs until 1993, at which time levels have been erratic, ranging from 84 feet bgs to 108 feet bgs. Wells S35-WC and S37-WC were used to monitor water levels until 1996, but have since been abandoned. Historic data show that water in the Wolf Creek Coal is a calcium sulfate type with an average TDS of 745 mg/I. Wadge Coal and Overburden The Wadge Overburden is considered to be an aquifer in this area and, for purposes of this discussion, is collectively grouped with the Wadge Coal aquifer. Four wells monitor the Wadge Coal seam and overburden, and two of the wells are in hydraulic communication with the Wadge Impoundment. Three wells remain in what is referred 18