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3.1.3 Groundwater <br />• As might be anticipated from no noticeable impact from dewatering activities conducted in the 1980's, <br />there has been no noticeable impact on groundwater hydrology from the gradual flooding of the New <br />Elk Mine. The apparent low vertical transmissivity and integrity of the surrounding rocks might inhibit <br />any effect of free water on the recharge of the overburden. The depths to which recovery might be <br />taking place are probably too far removed from the ground surface to manifest any impacts at the <br />surface (seeps and springs) at this time. <br />3.1.4 Piezometers <br />Refuse Disposal Area piezometer readings are included in this report (Table B-10). TH-201, on the first <br />bench, and TH-202 and TH-203 on the second and third benches had minimal water throughout the <br />year. Embankment stability, the primary purpose of the piezometers, is discussed within the quarterly <br />waste pile certifications. <br />3.2 WATER QUALITY <br />3.2.1 Springs and Seeps <br />There is no evidence that mining activities have affected the water quality of springs or seeps, <br />nor are such changes anticipated. Additional discussion of springs and seeps is contained in <br />• Appendix C. <br />3.2.2 Surface Water (Streams and Rivers, and Ponds and Direct Discharges) <br />Results of water monitoring by the USGS indicate a change in water quality between <br />Stonewall, a location above the New Elk Mine, and Madrid, a location below the Golden Eagle <br />Mine. These changes are probably a result of natural lowering of water purity due to geologic <br />parameters, geography (Stonewall is located on the Middle Fork of the Purgatoire River as is <br />the New Elk Mine, the Golden Eagle Mine is located below the confluence of the Middle Fork, <br />and Madrid is located yet below the confluence of the South Fork above Trinidad Reservoir), <br />contributions from the New Elk and other land uses (point and area sources water quality <br />change) between the two stations. The Stonewall site (07124050) acquires water from a 52.1 <br />square mile area and the Madrid site (07124200) measures water from a 505 square mile <br />watershed. <br />There is a natural deterioration of water quality as the stream flows out of the igneous terrains, <br />through sodic sediments, and into marine sediments. There is a relationship between Purgatoire <br />River water quality and flow quantities. From historic (USGS) information the minimum flow <br />of the Purgatoire River at Stonewall, above the two mine sites, is 4 cubic feet per second (cfs). <br />The conductivity was deduced to be 345 umhos/cm at a flow of 4 cfs. The minimum flow of <br />the Purgatoire River at Madrid, below the mine site, is 10 cfs and the average conductivity is <br />• 125 umhos/cm. In general, conductivity values are higher at lower levels of flow (suggesting <br />dilution during periods of snow melt or rain). <br />15