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West Elk Mine 2013 Annual Hydrology Report 6 <br />2.2 Stream Flow Data <br />The North Fork of the Gunnison River and Minnesota Creek are the major surface water <br />resources in the MCC permit area. The U.S. Geological Survey (USGS) maintains <br />gaging stations on both of these streams (USGS 09132500 and USGS 09134000, <br />respectively). Flows in these streams are dominated by snowmelt from upland areas, but <br />are affected by small upstream diversions for irrigation, and by storage and releases from <br />upstream reservoirs (USGS, 2014c; USGS, 2014d). The average daily flows in the North <br />Fork of the Gunnison River and Minnesota Creek in WY 2013 were well below historical <br />averages (USGS, 2014a; USGS, 2014b). <br />2.2.1 Flows in the North Fork of the Gunnison River <br />A summary of the average daily stream flow data for the North Fork near Somerset, CO <br />(USGS 09132500; Hydrologic Unit 14020004), including historical and WY 2013 data, <br />is graphically presented in Figure 6. Average daily flows for the North Fork near <br />Somerset, CO for WY 2013 ranged from 24 cubic feet per second (cfs) (15 days in <br />November and December 2012, and January 2013) to 2,100 cfs (May 17, 2013) (USGS, <br />2014a). The historical mean daily flows in the North Fork near Somerset, CO collected <br />from WY 1934 through WY 2012 have ranged from 63 cfs (5 days in January) to 2,190 <br />cfs (May 22) (USGS, 2014a). The average daily flows measured at the North Fork near <br />Somerset, CO gaging station in WY 2013 were below historical means from October <br />through July, and slightly above historical means in August and September (USGS, <br />2014a) (Figure 6). <br />The mean annual flow for the North Fork near Somerset in WY 2013 was 255 cfs, <br />corresponding to about 56% of the historical annual mean of 455 cfs for WYs 1934 <br />through 2012 (USGS, 2014a). The historical mean annual flows in the North Fork near <br />Somerset have ranged from 114 cfs in 1977 to 829 cfs in 1984 (USGS, 2014a; USGS, <br />2014c). The highest daily mean flow for the North Fork near Somerset in WY 2013 was <br />2,100 cfs on May 17, 2013 and the maximum recorded peak flow was 2,660 cfs on May <br />18, 2013 (USGS, 2014c). Flows in the North Fork of the Gunnison River can be <br />influenced by upstream releases and storage in the Overland and Paonia reservoirs (since <br />February 1962), small diversions for irrigation in nearby drainage areas, and irrigation of <br />about 3,000 acres upstream from the station (USGS, 2014c). <br />June 2014 HydroGeo, Inc. <br />