2008-03-31_PERMIT FILE - C1980007A (34)

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West Elk Mine • Additional baseline data were obtained in Horse Gulch, the west gulch located east of Horse Gulch, the east gulch located east of Horse Gulch and in the Deep Creek drainage above and below the coal lease boundary. Instantaneous flows, along with monthly peak flows, are measured with a crest stage gage. After baseline data were collected, West Gulch was eliminated from the monitoring program because the drainage was dry. A second Sylvester Gulch gaging location, Upper Sylvester Gulch, was added to the monitoring program in 1996. This gage location, shown on Map 34, was chosen because it is upstream of the first southeast longwall panel to be mined. Flows will be measured with a permanently installed nine-inch wide throat, Parshall Flume. Baseline data have been obtained for Box Canyon prior to longwall mining beneath the- drainage. Periodic monitoring has shown the drainage to be dry most of the time; however, monitoring will continue in accordance with the monitoring plan presented in Exhibit 71. In addition to providing baseline data, a portion of the Minnesota Creek gaging station network will be relied on to quantify stream depletions to Minnesota Creek (if any) from MCC's mining operations to provide the necessary augmentation water in accordance with the adjudicated plan (Exhibit 52). The extent of depletion, if any, will be quantified by correlating the streamflows of Minnesota Creek at the lower gaging station, approximately six miles upstream from its confluence with the North Fork, with sub-basins that could potentially be affected (Dry Fork and Lick Creek). A complete description of the streamflow correlation procedures is provided in the Application for Approval of Plan for Augmentation Concerning the Application of Water Rights of MCC in Gunnison and Delta Counties (WWE 1986) (Exhibit 52) and Engineering report, Water Augmentation Plan for MCC in Minnesota Creek Basin near Paonia (WWE 1985). As baseline hydrology data have been obtained in accordance with CDRMS regulations, some of the Minnesota Creek gaging stations have been decommissioned until the surnner before mining impacts are expected. Because MCC needs certain data to develop the streamflow correlations described in the augmentation plan, the following stations remain operational: n ;innesota Creek Lower (USGS) gaging station, Minnesota Creek Upper (USFS) flume, Lower Dry Fork flume, Lick Creek flume and the Upper Dry Fork flume. The Upper Dry Fork flume was relocated in November 1981, to a downstream location with a more stable channel to more accurately measure flows. Upper Dry Fork flume was relocated again in 2005 because a beaver pond flooded the original site. An additional site was placed at the flume crossing on Deep Creek in 2007. MCC has closed the Horse Creek flume, the South Prong flume and the East Fork upper station. Should mining advance to the point where these basins might be impacted, MCC :'Fill install new gaging stations, or reinstall the old stations, at least one monitoring seas-in L« ore an- potential exists for streams to be impacted. None of these drainages is within the ir.?ulence of mining in the permit area. In the event that conditions are such that the gage cannot be reinstalled at the same location, the site for the new gage will be reviewed with the CDRMS. Due to the storage in Minnesota Reservoir, the Dry Fork flows at the lower gage do not correlate . well with those measured at the upper gage. Consequently, MCC attempted to locate an appropriate gaging location immediately upstream of the reservoir. However, the channel is not 2.04-86 Revised Arovember 2004 PRI Q .Va7-ch 2006; Rev. April 2006 PR10; Rev. Afay 2006 PRIG; Sep. 2007 PR12. Feb. 2008 PR12