2016-07-21_REPORT - C1980007 - Laserfiche WebLink

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West Elk Mine 2015 Surface Water and Groundwater Quantity and Quality Data Summary 14 3.0 ASSESSMENT OF MINE -INDUCED HYDROLOGIC IMPACTS IN WY 2015 AND ANTICIPATED IMPACTS IN WY 2016 3.1 Surface Water MCC maintains a network of 23 stream flow gauging stations and eight temperature monitoring stations throughout the permit and lease areas (Table 3). Daily mean surface water flow summary tables are presented in Appendix A. Surface water flow hydrographs are presented in Appendix B and the field and laboratory surface water quality data are summarized in Appendix C. Tables and graphs of the Sylvester Gulch and North Fork temperature monitoring data are presented in Appendix I and Appendix J, respectively. 3.1.1 Impacts to Area Stream Water Quality Surface water quality data are collected for permit -specified parameters at monitoring stations throughout the permit area, in order to detect potential impacts of mining activities to surface water resources. Potential impacts to water quality in area streams are determined by comparing recent water quality and flow data to baseline values while considering effects of climatological factors, such as drought or high precipitation in areas near mining activity. Monitoring sites with values greater than 10 percent over comparable baseline maximums are noted in the table below. Field pH values were used for comparison when they were available, as the holding time for the lab pH is typically exceeded, due to the shipping time required for samples to reach the analytical lab. In general, water quality parameters that are above 10 percent over baseline maximums are likely due to natural variations in climate or flow conditions on the day the sample was collected. Impacts that appear to be directly linked to mining activities are noted. It should also be noted that baseline values are based on limited data and only give a general indication of seasonal variability. The surface water quality data for WY 2015 are presented in Appendix C. In WY 2015 none of the tested parameters were elevated 10 percent or more above maximum baseline values at the following surface water monitoring locations: Upper North Fork, Lower North Fork, Lower Minnesota Creek, Lower Dry Fork, Lick Creek, Upper Raven Gulch, and Deep Creek Ditch. The Lower Gribble Gulch, Horse Gulch, East Gulch, East of Horse Gulch, Box Canyon, and Deer Creek sites were dry, so there are no water quality data for these sites in WY 2015. There are no baseline data for comparison for Upper Minnesota Creek (WWE, 2001). Surface Water monitoring sites where tested parameters were elevated 10 percent or more above maximum baseline values are summarized in Table 9. These exceedances are not likely mining related, since mining discharges have not and are not occurring in the vicinity of the monitoring sites. The elevated measurements are likely due to natural seasonal variations. June 2016 HydroGeo, Inc.