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b. Groundwater <br />The largest and most useful alluvial deposits found in the region are <br />associated with the North Fork of the Gunnison River. Smaller, <br />more isolated alluvial deposits are associated with several of the <br />other tributaries of the North Fork. Directly adjacent to the Blue <br />Ribbon Mine along Hubbard Creek is a small alluvial deposit. <br />The most continuous sandstone unit of any significance in the <br />region is the Rollins Sandstone and the massive sandstone <br />separating the upper and lower coal members of the Mesaverde <br />formation. However, the latter massive sandstone produces very <br />little water, as evidenced by the dryness of the Bear Mine and the <br />lack of springs associated with this unit. Also, the Rollins sandstone <br />has been found to have insufficient yield to sustain ground water <br />supply wells (Orchard Valley Mine MRP). This unit lies 270 feet <br />below the F coal seam. <br />Occurrences of groundwater have been noted in the Mesaverde <br />Formation from information obtained from drilling, experience in <br />the mines, and from the presence of springs and seeps in the region. <br />This information also indicates that the only potential regional <br />bedrock aquifer in the area is the laterally continuous Rollins <br />sandstone. The laterally discontinuous lenticular sandstones within <br />the Upper Mesaverde Formation support only localized <br />groundwater. <br />Recharge to the Rollins sandstone occurs along outcrops, subcrops <br />beneath stream alluvium and in the channels of the North Fork and <br />its tributaries. However, due to the steepness of the topography in <br />the outcrop area (i.e., sandstones are ledge formers) and the <br />narrowness of the stream valleys, these units receive very little <br />recharge. Some recharge to the continuous units and much of the <br />recharge to the more discontinuous, lenticular units will come <br />directly from the percolation of snowmelt and precipitation <br />downward through sandstone lens and along fractures. <br />The Rollins sandstone is the only sandstone with sufficient porosity <br />and lateral extent to be considered a potential regional bedrock <br />aquifer. This sandstone outcrops one mile south ofthe Blue Ribbon <br />Mine in a narrow reach of the Hubbard Creek stream valley. The <br />only wells in the region which are completed in this aquifer are <br />located near the Hawk's Nest Mine along the North Fork of the <br />Gunnison River. <br />When faults and fractures are encountered in the North Fork region, <br />they generally produce mine inflows. The flow characteristics of <br />each mine inflow associated with faults and fractures depend upon <br />20 <br />