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-n- Preliminary aquifer tests were performed by ARCO on the Barren member of the Mesaverde Formation in September, 1975. The preliminary transmissivity ootained for this member was calculated to be 2.46 g/d/ft. Also, ARCO performed a preliminary aquifer test on a fractured area in the "F" seam which yielded a transmissivity of 16.68 g/d/ft. Another "F" sewn well completed in an unfractured area in the coal seam was dry. These aquifer tests indicate that the "F" sewn 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 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 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 obervations indicate that the "B-2", "E" and "F" coal seams and their roof strata are not significant reyional aquifers. Observations of mining within the "~" seam at the Bear No. 1 and No. 2 mines and of mining within the "D" seam at the Orchard Valley Mine indicate that the "C" and "U" seams and their asociated roof strata also are not significant reyional aquifers. If the coals and their roof strata were aquifers, these strata would have continued to weep throughout the life of these mines. Some fractures and faults transect the Mesaverde Formation and extend vertically to the surface. These faults and fractures produce narrow bands of secondary porosity within the rock strata. Uue to the low permeability of the rock strata within the Mesaverde Formation, these faults and fractures provide the primary path through which water flows both vertically between rock strata and horizontally within rock strata. When faults and fractures are encountered within the mines in the North Fork region, they generally produce mine inflows. The flow characteristics of each mine inflow associated with faults and fractures depend upon the lateral extent and the proximity of the fault or fracture to a stream valley. All inflows from these sources are characterized by an initial surge of water which then either decreases, or ceases completely with time. Since most stream channels in the North Fork drainage basin are developed in zones of weak fractured rock associated with fracturing and faulting (Dunrud, 1976), mine inflows from fractures and faults below these streams mimic the temporal flow characteristics of the overlying streams. In Hawk's Nest chine, an inflow was encountered under the ephemeral drainage of Hawk's Nest Creek. The rates of inflow beneath this drainaye fluctuate seasonally with a slight lag time in response to the flows in the overlyiny scream. In the Somerset Mine, inflows beneath Hubbard Creek are continuous and reflect the perennial nature of this scream.