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West Elk Mine 2007 Annual Hydrology Report 1 <br />is 1.0 INTRODUCTION <br />This Mountain Coal Company, LLC (MCC) West Elk Mine (Project) 2007 Annual Hydrology <br />Report (AHR) describes details of the hydrologic monitoring activities and summarizes pertinent <br />data with respect to mining operations as required by MCC's Permit C-80-007 with the Colorado <br />Division of Reclamation, Mining and Safety (CDRMS) for the Water Year 2007 (WY 2007), <br />October 1, 2006 through September 30, 2007. <br />1.1 Overview of Mining Operations <br />In WY 2007, mining was completed in longwall panels 19 and 20 and was advanced up to crosscut <br />23 in longwall panel 21. Development mining continued in longwall panels 18, 21, and 25 (see <br />Map 1). <br />2.0 HYDROLOGIC SUMMARY OF WATER YEAR 2007 <br />During WY 2007, October 2006 through September 2007, the total annual precipitation in the <br />vicinity of the West Elk Mine was above normal at McClure Pass (59743) and Paonia 1 SW <br />• (56306) stations compared to historical total annual precipitation data, but below normal at the <br />Overland Reservoir (59853) station (Colorado Climate Center, 2008). During WY 2007, the snow <br />water equivalent data were below historical annual averages at both Paoma 1 SW and McClure <br />Pass stations (NRCS, 2008), resulting in slightly below average to near average stream flows in the <br />nearby Project area (Figures 1-5). <br />2.1 Climatological Data <br />Precipitation and snow water equivalent (SWE) data for the Project area for WY 2007 were derived <br />from the Paonia 1 SW (56306), Overland Reservoir (59853), and McClure Pass (59743) <br />meteorological and Snotel stations (Colorado Climate Center, 2008; NRCS, 2008). Figures 1, 2, <br />and 3 depict the WY 2007 monthly average precipitation data compared to the 100-year historical <br />average for Paonia (1905-2005), and the 30-year historical averages for Overland Reservoir (1971- <br />2000), and McClure Pass (1971-2000). The total annual precipitation in WY 2007 was 7.38 inches <br />at Paonia, 10.0 inches at Overland Reservoir, and 14.70 inches at McClure Pass (Colorado Climate <br />Center, 2008). The total annual precipitation in WY 2007 corresponds to 126%, 85%, and 139%, <br />respectively, of the historical total annual precipitation values recorded at Paonia (5.84 inches), <br />• Overland Reservoir (11.7 inches), and McClure Pass (10.60 inches), respectively. <br />June 2008 HydroGeo, Inc.