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-z7- Occurrences of ground water have been noted in the Mesa Verde Formation from information obtained from drilling, experience in the mines, and from the presence of springs and seeps in the region. This information also indicates that the only potential regional bedrock aquifer in the general area is the laterally continuous Rollins sandstone. The laterally discontinuous lenticular sandstones within the Upper Mesa Verde Formation support only localized ground water flows. Recharge to the Rollins sandstone occurs along outcrops, along subcrops beneath stream alluvium and in the channels of the North Fork and its tributaries. However, due to the steepness of the topography in the outcrop areas (i.e, sandstones are cliff formers) and the narrowness of the stream valleys, the Rollins sandstone receives little recharge, except in the area under the North Fork of the Gunnison River and its associated alluvial deposits. Some recharge to the Rollins sandstone may come indirectly from the percolation of snowmelt and precipitation downward through faults and fractures. Drill holes which penetrated the Rollins sandstone near the Orchard Valley Mine wece initially dry, but after allowing these holes to recover some water accumulated, up to 300 gallons, in the casing. However, this amount of water is insufficient to provide a desirable well yield. This indicates that recharge along outcrops and subcrops above the level of the North Fork is insufficient to sustain ground water wells developed in the Rollins. The only domestic use of the water from the Rollins sandstone is from wells along the North Fork near the Hawk's Nest Mines. The water quality elsewhere is considered too saline for domestic use (Prince and Arrow, 1974). Preliminary aquifer tests were performed by WECC on the Barren member of the Mesa Verde Formation in September, 1975. The preliminazy transmissivity obtained for this member was calculated to be 2.46 g/d/ft. Also, WECC performed a preliminary aquifer test on a fractured area in the "F" seam which yielded a transmissivity of 16.68 g/d/f t. Another "F" seam well cortg~leted in an unfractured area in the coal seam was dry. These aquifer tests indicate that the "F" seam and the lenticular sandstones of the Barren member are poor aquifers at best, as ground water flow is mainly concentrated in fractured rock. Observations made underground by the staff of the Division at the Blue Ribbon, Hawk's Nest, Mt. Gunnison and Somerset Mines also indicate that the coal seams in the region are poor aquifers at best with very low transmissivities. The "B-2", "E" and "F" seams were observed to weep slightly at fresh cut faces, while mine entry walls a short distance from the face were dry. The sandstone and siltstone roof strata in the Mt. Gunnison, Blue Ribbon, Hawk's Nest and Somerset mines also weep for short periods of time following mining and eventually dry up. The Hawk's Nest Mine workings in the "E" seam are dry even though these workings are within 600 feet of the North Fork, are below the level of the North Fork, and are parallel to the North Fork. These in-mine observations indicate that the "B-2", "E" and "F" coal seams and their roof strata are not significant regional aquifers. Observations of