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2001 Hydrologic Report <br />3.2.2 Surface Water (Streams and Rivers, and Ponds and Direct <br />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 <br />changes are probably a result of natural lowering of water purity due to geologic pazameters, <br />geography (Stonewall is located on the Middle Fork of the Purgatoire River as is the New Elk Mine, <br />the Golden Eagle Mine is located below the confluence of the Middle Fork, and Madrid is located <br />yet below the confluence of the South Fork above Trinidad Reservoir), contributions from the New <br />Elk and other land uses (point and area sources water quality change) between the two stations. The <br />Stonewall site (07124050) acquires water from a 52.1 square mile area and the Madrid site <br />(07124200) measures water from a 505 square mile 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 ofthe <br />Purgatoire River at Stonewall, above the two mine sites, is 4 cubic feet per second (cfs). The <br />conductivity was deduced to be 345 umhos/cm at a flow of 4 cfs. The minimum flow of the <br />Purgatoire River at Madrid, below the mine site, is 10 cfs and the average conductivity is 125 <br />umhos/cm. 1n general, conductivity values are higher at lower levels of flow (suggesting dilution <br />during periods of snow melt or rain). Analyses at the Madrid station indicate glow-yield watershed <br />with the mean annual runoff volume measured at 28,980 acre feet. <br />In terms of local water quality of the Purgatoire River and associated alluvium, mine dischazge and <br />leachate from refuse contribute to higher ionization of the water and increased amounts of trace <br />elements. The main parameters of interest are sodium and other dissolved salts which may affect <br />downstream use of the water for irrigation. In the worst case, during low flow conditions, effects of <br />ionization caused by mining are insignificant when compared to the natural deterioration of water <br />quality as the river flows to the east. Figure 3.2-1 presents stiff diagrams of water quality at stations <br />PRS-1 and PRS-4 on the Purgatoire River for November 1997 through 2001. As shown, water <br />quality above the mine is similar to water quality below the mine. <br />Discharge from the site passes through treatment facilities or sediment impoundments. Copies of the <br />NPDES Discharge Monitoring Reports submitted to the Colorado Department ofPublic Health and <br />Environment are sent to CDMG as they are filed quarterly. No discharges from ponds at New Elk <br />were recorded during 2001. <br />3.2.3 Alluvial Groundwater <br />Wells in the Purgatoire River alluvium, (stations PAW-1 through PAW-9) were monitored during <br />the year. Stiff diagrams of wells PAW-1, PAW-2, PAW-8 and PAW-9 in the alluvium at New Elk <br />are shown in Figure 3.2-2. This shows slight decreases over the past five years in salinity in alluvial <br />ground water quality in response to decreased mining activity. <br />626-Annual Hydrolic Monitoring (Apc9.02).doc 16 <br />Apd117, 2002 <br />