2015-07-01_REPORT - C1980007 - Laserfiche WebLink

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West Elk Mine 2014 Annual Hydrology Report 46 5.0 ASSESSMENT OF MINE -INDUCED HYDROLOGIC IMPACTS IN WY 2014 AND ANTICIPATED IMPACTS IN WY 2015 5.1 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, Map 2). 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. 5.1.1 Impacts to Area Stream Water Quality As mentioned previously, 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 discussion 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 2014 are presented in Appendix C. In WY 2014 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 Minnesota Creek, Lower Dry Fork, Lick Creek, Upper Raven Gulch, and Lower Raven Gulch. The Horse Gulch and Box Canyon sites were dry, so there are no water quality data for these sites in WY 2014. There are no baseline data for comparison for Upper Minnesota Creek (WWE, 2001). Data from two sampling rounds (May 20 and September 23, 2014) plus one duplicate for each sampling round were collected at the Lower North Fork monitoring site in WY 2014. The May 2014 total iron concentrations at this site were 4.21 mg/L (4.29 mg/L duplicate) compared to the baseline maximum of 3.8 mg/L. The May 2014 total suspended solids (TSS) concentrations were 133 mg/L compared to the baseline maximum of 107 mg/L. Data from one sampling round (May 21, 2014) were collected at Upper Sylvester Gulch in WY 2014. Three parameters were elevated 10 percent or higher than the maximum baseline values. Field measured electrical conductivity (EC) values were 733 µmhos/cm June 2015 HydroGeo, Inc.