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West Elk Mine 2004 Annual Hydrology Report 40 erosion and sediment deposition the control channels used to calibrate the pressure transducers and gauge the stream flows are constantly changing and the flow data collected for Deep Creek in WY 2002 (HydroGeo, 2003), WY 2003 (HydroGeo, 2004), and WY 2004 is not considered reliable. The data and graphs presented in this report were developed using a rating curve developed from recent channel geometries but the raw data for these stations remains suspect. The Upper Dry Fork stream station was submerged by a beaver pond in WY 2002 and remained inoperable in WY 2004. The Upper Dry Fork Flume will be reestablished in the summer of 2005. )n addition, the Lower Dry Fork and Upper Minnesota Creek flumes will be cleaned out and modified to improve flow through. Since the well casings have collapsed in monitoring wells SOM-45-H1 (Sept. 2002), SOM-2-H (Jul. 1999), SOM-16-H (Sep. 2000), 96-27-1 (Apr. 2002), and SO.W-1 (Jun. 2002) over the past few years, the water quality and water level data collected is not considered to be 100% reliable. These wells are dysfunctional so future monitoring data collection at these locations will not provide useful data. 7.0 SUMMARY During WY 2004, the Project was in regulatory compliance with all hydrologic aspects. Mining operations did not cause any significant impacts to local surface or ground water resources. The drought conditions during the past few years abated in WY 2003 and WY 2004 and flows to surface streams were near normal. Spring flows have improved, but remain below normal. The water levels in most of the ground water monitoring wells have remained relatively constant over time. However, monitoring wells that aze above-or down-gradient of active longwall mining often times show lower water levels. Since mining commenced in the Box Canyon Panel area water levels in monitoring wells 01-11-1 and RAV 4b, both located down-gradient of active mining have dropped, and are likely the result of dewatering of the B-Seam. Water levels in wells typically recover to pre-mining levels several months to several years after longwall mining in the area ceases. The casings of wells SOM-2H and SOM-16H have collapsed, most likely due to mine- induced subsidence, but these effects have been limited. As MCC's mining operations shifr from the west side of the Project area to the south and east side, the Project's hydrologic monitoring program must be revised accordingly. A hydrologic monitoring system must be established in areas of future mining s, so that adequate and reliable baseline data can be collected. Table 12 summarizes the recommended revisions to the existing • August 2005 HydroGeo, Inc.