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In summary, with regard to the North Fork of the ~ <br />• Purgatoire River surface flow, 48.23 acre feet were withdrawn <br /> in 1993, and 139.71 acre feet released, increasing surface flow <br /> by 91.47 acre feet. <br /> Impacts of Longwall and Retreat Mining on Hydrologic <br /> Resources Longwall and retreat mining at the Golden Eagle Mine <br /> will result in subsidence. This has the potential to shift the <br /> elevation of the ground surface as much as the thickness of the <br /> coal which will be extracted in certain locations. Maximum <br /> subsidence is anticipated down the center of the longwall <br /> panels, with lower amounts of subsidence along the perimeters <br /> of the panel. This may result in an interruption of surface <br /> drainage patterns and may modify the characteristics of water <br /> bearing formations within the overburden. <br /> Evidence for interruption of surface drainage patterns <br /> would consist of ponding of water within stream channels <br /> associated with subsequent drop features, dislocation of stream <br /> channels, decreased or non-existent flows, or high levels of <br />• mine inflows immediately below the streams within the mine. <br /> Basin performed a field reconnaissance of channel reaches <br /> overlying longwall panels in Ciruela Canyon, Santistevan Canyon <br /> and Zamora Canyon to ascertain the presence of geomorphic <br /> impacts. These areas had overburden ranging in thickness from <br /> 415' to 600', and showed no visual evidence of geomorphic <br /> discontinuity. Water monitoring in Ciruela Canyon and <br /> Santistevan Canyons have not shown variations in flow outside <br /> of expected standard seasonal fluctuations. Nine springs or <br /> seeps within one mile of the New Elk and Golden Eagle permit <br /> boundaries have been monitored annually in late summer for ten <br /> years without showing any trends in their yield (Basin, 1994). <br /> Mapping of mine inflows has been performed annually and the <br /> results have been included in the Annual Hydrology Reports. <br /> The stream channels in the area have been superimposed on these <br />' 1993 discharge of 84 gpm is equivalent to 136 ac ft (mine pumping) + 3.7 domestic surge <br />• at Golden Eagle or 139.7 ac ft. <br />2.05-44 (Revised Oa/2~/9a) <br />