2018-09-04_PERMIT FILE - C1980007 (18)

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MCC West Elk Mine Sunset Trail Lease Modifications 2011 Hydrology Survey 10 ti 3.3 South Prong Creek Drainage The South Prong Creek drainage encompasses an area of about 1.89 square miles (1,210 acres) and 'includes two major forks - a northern fork with a northern branch and a southern fork with a southern branch. The drainage ranges from about 11,400 to 7,720 feet amsl with an overall average gradient of 1,314 feet per mile. Approximately 1.16 square miles (-743 acres) lies in the STLM study area (Figure 2). South Prong Creek was flowing during the survey period. The highest concentration of springs, ponds and wetlands in the STLM study area occurs in the South Prong Creek drainage. Data collected at the various survey sites in the STLM study area in the South Prong Creek drainage are summarized in Table 3. Thirty-one sites were identified in this area during the survey (Figure 2) including 22 springs or springs with ponds and/or wetlands and seeps; 7 ponds or ponds with associated wetland areas; and 2 wetland areas without associated ponds or springs. The site summary sheets and photos for the South Prong Creek drainage are presented in Appendix C. 3.3.1 Springs and Seeps The locations of the South Prong Creek spring and seep related sites are depicted on Figure 2. The elevations for the 22 springs and seeps or springs with ponds and/or wetlands mapped ranged from 8,383 to 9,613 feet amsl. The average spring flows ranged from a trickle to greater than 20 gpm. Seven of the 22 springs in this drainage had flows greater than 2 gpm. The spring at site 58 had the highest flow encountered during the survey, greater than 20 gpm. The areal extent of spring/wetland areas ranged from 36 to 40,000 ft2 (0.92 acres). The field pH values ranged from 6.15 to 7.63 s.u.; electrical conductivity ranged from 61 to 457 µS/cm; and temperatures ranged from 1.1 to 11.4° C (Table 3). 33.2 Ponds Five ponds or ponds with wetlands were identified in the South Prong Creek drainage during the surveys. The pond/wetland areal extents ranged from about 2,205 ft2 to 6,750 ft2(0 .05 to 0.15 acres). Several of the ponds had dams created by beavers and/or were man-made and ranged from shallow depths of a few inches to more than three feet deep. Several of the ponds had evidence of animal use such as animal tracks and wallows. The pond elevations ranged from 8,380 to 9,610 feet amsl. The temperatures ranged from 4.9 to 10.7'C; pH values ranged from 6.71 to 7.37 s.u., and the electrical conductivity values ranged from 86.4 to 232 µS/cm. February 2012 HydroGeo, Inc.