2010-05-03_HYDROLOGY - C1980007 (2)

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Appendix A West Elk Mine ' coverage throughout the lease area. Along with the water quality analysis in Exhibit 19, a comparison of the water quality analysis of the springs to water quality standards recommended by the State of Colorado has been performed. Indications are that spring water quality is good. Most ' of the springs located above the F -Seam show total dissolved solids (TDS) local and that there is not a large continuous groundwater reservoir supplying these springs. In general, the quality of water issuing from springs below the F -Seam is just below that of waters from the overburden. Furthermore, Mayo and Associates conducted a hydrogeologic analysis of the permit and adjacent area in 1999? The complete report is included in Exhibit 18. To summarize Dr. Mayo's findings: the groundwater systems are localized, are not areally extensive, and tend to form discrete groundwater bodies that are not in hydrodynamic communication with each other. Therefore, impacts to the water quality of a spring due to underground mining are highly unlikely. Monitoring rf .Reservoirs and Stock Ponds ' Although water level measurements are not taken on Minnesota Reservoir, the Upper and Lower Dry Fork flumes provide an estimate of the reservoir in flows and outflows. T be planned retrofit of the ditch company's flume upstream of the reservoir will improve the accuracy of the reservoir inflow measurement. In addition, the West Elk Mine, in cooperation with the U.S. Forest Service (USFS), Paonia Ranger District in Paonia, Colorado, has agreed to informally monitor the USFS surface water resources ' (stock ponds), as depicted on Map 37, that are located directly over longwall panels to be mined or within the angle -of -draw per the agreement letter in Exhibit 19C. In addition to the commitments ' provided in Exhibit 19C, MCC will also photograph on a yearly basis the resources that are located over longwall panels to be mined or within the angle of draw. The results of the monitoring will be included in the Annual Hydrology Report. Table S lists the USFS water resources within or adjacent to the West Elk Mine permit area_ Surface Water Quantity Strews Based upon the monitoring program previously described, this section provides an overview of the existing streamflow regime for the watersheds in the vicinity of the West Elk Mine. Included are discussions on avera annual flows, low flows, peak flows, and issues relating.. to channel morphology and sediment yield. Strearflow Most of the streams in the permit area are ephemeral, flowing only in response to snowmelt or significant rainfall events. Using Sylvester Gulch as an example, "significant" rainfall (Biased on the conceptual -level application of the U.S. Soil Conservation Service curve - number (CN) approach), means that a precipitation amount or snowrnelt equivalent of about one inch in 2d- hours is required to generate runoff. 2.04 -70 Revised -r 1995 PROS; F2visedii n 1998 PRO; Re wised lar 1999 X88