2016-07-21_REPORT - C1980007 - Laserfiche WebLink

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West Elk Mine 2015 Surface Water and Groundwater Quantity and Quality Data Summary 16 3.1.2 Impacts to Area Stream Water Quantity Stream flows at the monitoring sites for the Upper North Fork (USGS), Middle Sylvester Gulch, Lower Minnesota Creek, Upper Minnesota Creek Flume (USGS), Upper, Lower and Middle Dry Fork Flume, Lick Creek Flume, Deep Creek Ditch, and the Minnesota Reservoir Flume stations are measured with data loggers that collect data continuously. Stream flows of the other monitored streams (Upper and Lower Sylvester Gulch, Lower Gribble Gulch, Horse Gulch; East Gulch east of Horse Gulch, Upper and Lower Deep Creek. Box Canyon, Upper and Lower Raven Gulch, Deer Creek, and Poison Gulch) are measured as instantaneous flow three times per year, corresponding with rising limb, peak flow, and low flow periods. No specific flow data are available for the Lower North Fork, although no stream flow impacts from mining are expected. Flow at Lower Sylvester Gulch is not measured, because of its close proximity to the Middle Sylvester Gulch Flume. Potential mining related impacts to stream flows are based on dramatic decreases or total loss of stream flow due to subsidence. Based on the flow monitoring data through WY 2015 (Appendices A and B), there are no mining -induced impacts to the water quantity of these streams. 3.2 Springs and Seeps MCC currently monitors 40 springs and seeps (Table 5). Hydrographs of the spring and seep flows are presented in Appendix D and the spring and seep water quality data are presented in Appendix E. 3.2.1 Impacts to Spring and Seep Water Quality Spring water quality data are collected for permit -specified parameters at monitored springs and seeps throughout the permit area, in order to detect potential impacts of mining activities. Typically, underground coal mining does not impact spring water quality, but it can reduce or eliminate flows due to subsidence or dewatering. Water quality data from WY 2015 do not indicate significant changes from baseline conditions for most of the monitored springs. However, many of the springs had slightly elevated TDS/TSS, iron, and/or conductivity values that were also noted in WYs 2004 through 2014. These elevated values are likely the result of seasonal variations and are not related to mining operations. Potential mining impacts to area spring and seep water quality are determined by comparing current water quality data to maximum baseline values and climatological conditions such as drought or high precipitation periods at monitored sites hydraulically connected to areas with mining activities. 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. The discussion below includes monitoring locations where one or more parameters had values 10 percent or higher than comparable maximum baseline values. Spring water quality parameters that are above 10 percent of the baseline maximum are typically the result of natural variations in climate or flow conditions the day the sample was collected. It should also be noted that baseline values are based on limited data and only give a general indication of seasonal variability. June 2016 HydroGeo, Inc