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There is little development of the ground water resource in the local area. The few wells that <br />have been completed in the Williams Fork interbedded sandstones yield less than five gallons per <br />minute and their uses are limited to domestic and/or livestock use. Nearby residents haul <br />drinking water supplies from Craig and Meeker. <br />Saturation of the Williams Fork sandstones is weak to nonexistent, with the flow controlled by <br />the geologic structure of the Collom Syncline in a down dip direction. Ground water direction <br />follows the geologic structural trend and flows to the northeast. Following the down dip <br />direction, where the ground water flow meets the land surface, infrequent discharges from the <br />Williams Fork formation are seen as seeps and springs on the valley walls of Goodspring and <br />Taylor Creeks. Further analysis of the Goodspring and Taylor Creek basins show the recharge <br />rate to be 0.2 to 0.35 inches per year from the Williams Fork surface outcrop area. Annual <br />pleVlplta 1V11 aiieS viii fear tv year, and UU tv tvpvglaFl j% and eievativii changes, vaiicS even <br />across the permit area. Precipitation averages 21.5 inches, but has been recorded at less (12.45 to <br />18.6 at the Permit area during 1978-1980) (PAP, Table 7). <br />The Iles Formation, of varying thickness, is located beneath the Williams Fork Formation (and <br />the coals to be mined). The Trout Creek Sandstone, a regional aquifer reaching thickness of up to <br />75 feet, is located within the Iles Formation. The Trout Creek sandstone is fine, well sorted, <br />calcareous, and is a continuous unit that can be correlated over a large area. It is mainly from this <br />sandstone member that the two creeks on the permit area, Goodspring and Taylor, receive their <br />flow. The Trout Creek Sandstone is believed to contain water due to a saturation zone found <br />beneath Goodspring Creek. The recharge areas for the sandstone are south of the permit area in <br />the higher elevations or where the Trout Creek sandstone is exposed at the ground level and <br />subsequently has been eroded above the Goodspring Creek elevation. <br />Hydraulic conductivities of the sandstones below the coal seams to be mined are variable but <br />low, with average transmissivity of 40 gallons per day per foot. Little water is recharged, <br />transmitted or discharged from the permit area. Drawdown analysis of two wells, Taylor No. 1 <br />and No. 3, both drilled into the Trout Creek Sandstone, showed an average transmissivity of 40 <br />and 260 gallons per day per foot and hydraulic conductivity of 3.4 and 0.13 gallons per square <br />foot, respectively. Porosity and permeability characteristics of this aquifer were not calculated <br />due to the depth of the sandstone and lack of corresponding data from other locations within the <br />Iles Formation. Storage coefficient for one well, Taylor No. 1, was 0.066, but should only be <br />considered a factor for that well and not the Iles Formation as a whole since no reference data is <br />available. <br />The proposed mining operations are not expected to decrease the water quality or quantity of the <br />Trout Creek aquifer. Since the Trout Creek Sandstone member underlies the deepest coal seam <br />to be mined by 800 feet, it is estimated that Colowyo's operations should not impact this aquifer <br />in any manner. <br />Proposed Decision and Findings of Compliance <br />Permit Renewal 05 <br />14 September 2009 <br />Page 42 <br />C