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West EIk Mrne As noted above, if a party intends to dredge and/or frll in a regulatory wetland, a 404 permit must be acquired in advance of the activity. Note that the regulatory "trigger" is dredging and/or filling. • No such activities aze proposed in the Apache Rocks or Box Canyon permit revision azea. To ascertain whether potential wetlands impacts caused by mining-induced subsidence would be regulated under Section 404, MCC representatives met with staff from the U.S. Army Corps of Engineers (USAGE), Grand Junction office in September 1994. In this meeting, USAGE staff indicated that, at the West Elk Mine, wetlands impacts as a consequence of subsidence would not be regulated. In addition, due to the many reasons presented above regazding the general lack of impacts to streams, spring/seeps and groundwater, it is unlikely that the wetlands in the Apache Rocks and Box Canyon permit revision azea will be significantly affected by the mining. The wetlands in question derive their water from surface drainages and spring/seeps. WWE's calculations indicate that the maximum potential spring and streamflow loss in the current permit and Box Canyon permit revision areas is less than 3 acre-feet per yeaz. A loss of this magnitude, especially when distributed over the full permit revision area, is of no consequence relative to the wetlands. If the total annual surface water and spring "losses" of 3 acre-feet were to reemerge downgradient, slope stability is not likely to change significantly. The introduction of 3 acre-feet of additional groundwater discharge is smaller than the natural, yeaz-to-yeaz fluctuations in groundwater dischazges. This finding, coupled with the small wetlands acreage in the Apache Rocks and Box Canyon permit azeas, leads to the conclusion that the probable hydrologic consequences from the perspective of wetlands aze not significant. Water Rights ' .~ Back2round-This section discusses the potential effects on vested water rights that may be caused by MCC's longwall mining operation, and the associated subsidence in the permit azea. The location of Apache Rocks and Box Canyon permit revision azeas are shown on Map 1 A. Related impacts include inflows from faults and storing water in underground sumps. Al] of these topics are addressed herein. The water rights analysis has been prepazed by WWE with 35 years of experience in this subject. W WE recommends that readers review the next major section of this report Mine Water System for background to facilitate an understanding of water management at the mine, and associated water rights implications. The proposed longwall mining operation within the current permit and Box Canyon permit revision areas could potentially affect water supplies and water rights in the Dry Fork and North Fork drainages. Each drainage and its accompanying water rights that could potentially be affected by subsidence is discussed below. Following this discussion is an evaluation of the water rights aspects of the sealed panels sumps, fault inflows, and MCC's North Fork diversions. In the following analysis, the term "depletion" is calculated as diversions minus return flows. Drv Fork Drainage -MCC has a comprehensive decreed water augmentation plan ($6CW38) in place to mitigate the possible mining related depletions to Minnesota Creek and its tributaries. l • Approximately 60 percent of the Apache Rocks permit revision azea mining is planned in the Dry 2.05-168 RevisedJutt. 7995 PR06: RevisedNw. 1998 TR80; RevisedJnttuary 1998 PROS