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the potential for depletions to the aquifer systems and can cause both ,surface and ground water quality degradation. This section will explore the impacts on the hydrologic regime by of the underground mining being conducted in and being proposed for the Eagle No. 5 and No. 6 Mines. It is important to note that the mining which could generate the major hydrologic impacts from the Eagle No. 5 Mine has already occurred at this time. The No. 5 mine is now progressing updip in the Williams Fork Mountains away from areas where the Williams Fork and Yampa stream/alluvial systems were undermined. Operations are in the planning stage for the Eagle No. 6 mine which will largely underlie the No. 5 Mine, at least during the first five permit years. Ground Water Some depletion of water from the local bedrock aquifers is expected to result from these mining operations but, as discussed below, this depletion is not considered significant. The discharge of water from the mines will affect surface water quality, but not to the extent that use would be limited. Assuming that the portals are properly sealed when the mines are abandoned and allowed to flood, some effects on water quality in the Williams Fork alluvium is anticipated as a result of discharge of mine water through subcrops of the "E" and "F" seams. The magnitude of this impact is problematical and will be discussed in this section. Empire Energy Corporation has provided a discussion of the probable hydrologic consequences of the Eagle No. 5 and No. 6 mines to the ground water regime. The projected impacts are as follows: 1. Depletion of aquifers overlying and underlying the coal seams as well as depletion of the stream/alluvial system of the Williams Fork River; 2. Depletion, through use, of water in the Trout Creek sandstone; and, 3. Degradation of ground and surface water quality through mine water discharges. The Eagle No. 5 mine requires pumping to prevent flooding of the mine workings. The discharge rates of this mine water to the surface are monitored on a weekly basis and averaged between 600 and 800 gpm during 1985. Based an modeling, Empire Energy Corporation has estimated that combined inflow into the No. 5 and No. 6 Mines will range hetween 860 and 1070 gpm by: the end of the first permit term. This inflow will increase in subsequent years as the No. 6 Mine is expanded. The operator's worst case estimate of total maximum inflow into the No. 5 and No. 6 Mines is 2,490 gpm by the 20th permit year. Empire Energy Corporation has conducted annual inflow studies of the Eagle No. 5 Mine since 1983. In these studies the sources of mine inflows are identified as specifically as possible under existing operating conditions, the individual rates of inflow are measured where practical, and the total is the sum of these inflows. The major sources of mine inflow are two of three normal faults encountered in the Two West Mains. The T985 mine study reported that approximately 308 gpm inflow occurs by means of these faults. This _29_