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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 Stonewall, a <br />location above the New Elk Mine, and Madrid, a location below the Golden Eagle Mine. These changes <br />are probably a result of natural lowering of water purity due to geologic parameters, geography <br />(Stonewall is located on the Middle Fork of the Purgatoire River as is the New Elk Mine, the Golden <br />Eagle Mine is located below the confluence of the Middle Fork, and Madrid is located yet below the <br />confluence of the South Fork above Trinidad Reservoir), contributions from the New Elk and other land <br />uses (point and area sources water quality change) between the two stations. The Stonewall site <br />(07124050) acquires water from a 52.1 square mile area and the Madrid site (07124200) measures water <br />from a 505 square mile watershed. <br />There is a natural deterioration of water quality as the stream flows out of the igneous terrains, through <br />sodic sediments, and into marine sediments. There is a relationship between Purgatoire River water <br />quality and flow quantities. From historic (USGS) information the minimum flow of the Purgatoire River <br />at Stonewall, above the two mine sites, is 4 cubic feet per second (cfs). The conductivity was deduced to <br />be 345 umhos/cm at a flow of 4 cfs- The minimum flow of the Purgatoire River at Madrid, below the <br />mine site, is 10 cfs and the average conductivity is 125 umhos/cm. In general, conductivity values are <br />higher at lower levels of flow (suggesting dilution during periods of snow melt or rain). Analyses at the <br />Madrid station indicate aloes-yield watershed with the mean annual runoff volume measured at 28,980 <br />acre feet. <br />In terms of local water quality of the Purgatoire River and associated alluvium, mine discharge and <br />leachate from refuse contribute to higher ionization of the water and increased amounts of trace elements. <br />• The main parameters of interest are sodium and other dissolved salts which may affect downstream use of <br />the water for irrigation. In the worst case, during low flow conditions, effects of ionization caused by <br />mining are insignificant when compared to the natural deterioration of water quality as the river flows to <br />the east. Figure 3.2-1 presents stiff diagrams of water quality at stations PRS-l and PRS-4 on the <br />Purgatoire River for November 1997 through 2001. As shown, water quality above the mine is similar to <br />water quality below the mine. <br />Discharge from the site passes through treahnent facilities or sediment impoundments. Copies of the <br />NPDES Discharge Monitoring Reports submitted to the Colorado Department of Public Health and <br />Environment are sent to CDMG as they are filed quarterly. No discharges were noted at any of the ponds <br />in 2005. <br />r <br />3.23 Alluvial Groundwater <br />Wells in the Purgatoire River alluvium, (stations PAW-1 through PAW-9) were monitored during the <br />year. Stiff diagrams of wells PAW-1, PAW-2, PAW-8 and PAW-9 in the alluvium at New Elk are shown <br />in Figure 3.2-2. This shows slight decreases over the past five years in salinity in alluvial ground water <br />quality in response to decreased mining activity. <br />• <br />16 <br />