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II. Water Quality Impacts <br />Surface Water <br />Golden Eagle Mine <br />The 1980 WWL report describes the water quality of the mine discharge at the site and makes <br />a weighted average prediction of the impact of discharges on flows within the Purgatoire. Table <br />8 compiles historic mine discharge data from both mines in conjunction with Stonewall water <br />quality data. The historic mine discharge water quality varies from what had been noted <br />previously in that the discharge from Golden Eagle is less saline than originally reported, with <br />less calcium and magnesium and more sodium than noted earlier. Iron and manganese levels <br />have also been lower. The historic mine discharge quality at the New Elk Mine was more saline <br />than noted in 1980, with correspondingly higher concentrations of bicarbonate, chloride, sodium <br />and sulfate. Iron concentrations were higher and manganese levels were about the same. Slight <br />changes in geological Provence or mining technique may be responsible for these changes. <br />Figure 8 is a reflection of mean concentrations of major cations and anions in the river and the <br />• alluvium up and downstream of the Golden Eagle Mine. Site PRS-3, downstream, generally has <br />slightly higher concentrations of each parameter, but greater increases of sodium. The lower <br />sites practically have indistinguishable characteristics on this graph. <br />The original WWL report estimated the loading of chemical parameters on a low flow of 5 cfs <br />and a mean flow of 20 cfs. The mine has not experienced a flow near 5 cfs, so it is difficult <br />to evaluate the veracity of that projection. The mine has seen flows in the range of 20 cfs, and <br />the November, 1993, results at PRS-3, at 13.13 cfs suggest that the predicted concentrations of <br />calcium, chloride, magnesium and manganese were higher than expected, while the sodium <br />concentration was lower than anticipated (Table 9). The Stonewall and site PRS-1 data reflect <br />a calcium bicarbonate water with a mean TDS of 166 mg/l; the mine is discharging a sodium <br />bicarbonate water with a mean TDS of 815.5 mg/1 versus 1112 mg/I anticipated earlier. This <br />does not account for the changes observed at the site. <br />The projections are revised to utilize a mean low flow of 4 cfs and to reflect the highest <br />concentrations of parameters observed in the discharge from GE-002. Predictions of water <br />quality for existing conditions and the life-of-mine are compiled on Table 10. It is worthwhile <br />to note that neither the reported data nor the predicted values exceed recommended water quality <br />criteria, receiving stream standards and nor do they present a threat of material damage from <br />mining. <br />lJ <br />25 <br />