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Williams Fork is a 50 to 500 feet thick sequence of sandstone, siltstone, <br />shale, and thin coal, including the Lennox Coal Seam. <br />Ground water in the Williams Fork tends to flow downdip. The movement <br />of water and the horizontal extent of the formation is limited by outcrops in <br />the eastern and central parts of the permit area. <br />Generally, the Williams Fork is found to be in an unconfined state, however, <br />locally or seasonally the formation may exhibit semi-confined conditions. <br />Seasonal fluctuations are probably the result of recharging and dewatering a <br />perched aquifer within the formation. <br />Although aquifer tests were not performed on the overburden at the site, <br />aquifer characteristics have been extrapolated from Colorado Yampa Coal, <br />located about 15 miles southeast. Data obtained from these tests indicate <br />that transmissivity values for the overburden could range from 3 to 20 <br />gallons per day per foot (0.4 to 2.7 FTz per day), while storativity may vary <br />from 1 x 10"Z to 1 x 10"5 as local conditions change. <br />One well was sampled for water quality. Analyses of this magnesium - <br />calcium bicarbonate water shows elevated levels of iron, manganese, TDS, <br />and zinc. The high zinc values are probably due to contamination from the <br />galvanized well screen. The high iron, TDS and manganese values preclude <br />use of this water as a drinking supply. Williams Fork water is suitable for <br />stock watering and irrigation of salt tolerant plants. <br />Hubberson Gulch Alluvium <br />The alluvium in Hubberson Gulch occurs in the lower reaches of the gulch <br />in and adjacent to the permit azea. Depth to water data indicates that the <br />aquifer may vary from semi-confined to water table conditions. The amount <br />of head, if any, is generally less than 5 feet. Water quality analyses of two <br />alluvial wells indicate that these calcium-bicarbonate type waters do not <br />meet U.S EPA drinking standards. Manganese, sulfate, TDS, and chromium <br />are found to be in excess of standards. These waters do meet stock <br />watering criteria, and may be used for irrigation dependent upon crop and <br />soil characteristics. <br />Springs and Seeps <br />An initial spring survey in July, 1979, located 49 springs and seeps in and <br />near the permit area. The majority of these springs and seeps occur in <br />valley bottoms. The recharge to these valley bottom springs may be from a <br />discontinuous alluvial aquifer, from colluvial slumps, or from perched <br />aquifers draining to stream sediments. Several springs issue from the <br />Williams Fork Formation, while two others issue from the overlying Twenty <br />Mile Sandstone. Some of the springs are used to fill stock ponds in the <br />22 <br />