2013-07-02_REPORT - C1980007 (3)

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West Elk Mine 2012 Annual Hydrology Report 16 3.1.3.2 Dry Fork Flumes 3.1.3.2.1 Upper, Middle, and Lower Dry Fork Flumes Dry Fork is an ephemeral stream that is tributary to middle Minnesota Creek. There are four surface water monitoring stations in the Dry Fork: Upper Dry Fork Flume, Middle Dry Fork Flume, Lower Dry Fork Flume, and Minnesota Reservoir Flume (Section 3.1.3.2.2). The Upper and Middle Dry Fork stations were established to monitor the SOD mine panels area. The Lower Dry Fork station was established to monitor the SOD mine panels area and the southwest mine panels area (Map 2). These stations were also established to support the Minnesota Creek Augmentation Plan. The Upper, Middle, and Lower Dry Fork stations have 30 -inch Parshall flumes and data loggers. In October 2005, the Upper Dry Fork Flume monitoring station was relocated further upstream and replaced the initial site, because it was frequently flooded by beaver dams. MCC initiated new monthly baseline monitoring of this relocated site in WY 2006 and routine monitoring (three times per year) began in WY 2007. The Lower Dry Fork Flume was replaced in its same location in October 2006 (WY 2007). Monitoring at the Upper, Middle, and Lower Dry Fork flumes began in 1977. 3.1.3.2.2 Minnesota Reservoir Flume MCC installed a 30 -inch flume and a data logger at the Minnesota Reservoir monitoring station above the high water line of Minnesota Reservoir in October 2006 (WY 2007). The Minnesota Reservoir station was established to monitor the SOD mine panels area and the southwest mine panels area (Map 2). The Minnesota Reservoir Flume monitoring station (Map 2) provides more accurate and more representative monitoring data than the Lower Dry Fork flume, since it isn't influenced by water storage and releases from Minnesota Reservoir. Baseline monthly monitoring of the Minnesota Reservoir Flume was conducted in WY 2006. Routine monitoring (three times per year) at this location began in WY 2007. In WY 2010 this flume was relocated to the north by about 15 feet to better avoid flooding caused by beaver activity. 3.1.3.3 Deep Creek Ditch Flume Deep Creek Ditch is a trans -basin diversion ditch that routes water from the Little Gunnison Creek to Upper Dry Fork, in order to provide irrigation water for users in the Minnesota Creek Basin, and for storage in Minnesota Reservoir. The average annual diversions for Deep Creek Ditch are about 1,000 ac -ft. A concrete flume and continuous recording data logger were installed in this ditch in the fall of 2006 (Map 2). Baseline monthly monitoring of the Deep Creek Ditch flume was conducted in WY 2006. Routine monitoring (three times per year) at this site began in WY 2007. Data from this station provide information on trans -basin diversions versus natural flows in Dry Fork and Deep Creek. This flume is located up- gradient of the SOD mine panels area. June 2013 HydroGeo, Inc.