2008-09-29_PERMIT FILE - C1981019A (6)

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RULE 2 PERMITS primarily to the greater number of samples taken by the USGS which included a greater number of storm events and continuous measurements over these storm hydrographs. The USGS data, in this case, is more appropriate as an absolute indicator of suspended solids values for Taylor Creek. However, even though the absolute values are significantly different, the ratios between the mean and the standard deviation are similarly large, reflecting the extreme natural variability of these constituents. Comparison of specific conductivity shows that little difference occurred in the data sets as a result of different sampling regimes. In fact, the mean values all fall within the 95% confidence intervals of the comparable study. Other water quality constituent levels remained similar to those collected in the earlier periods. As a further part of the EMRIA Program, Parker and Turk (1981) of the USGS used data collected from Taylor Creek and Wilson Creek in a publication dealing with several watersheds in the larger Yampa River Basin. This publication is included in its entirety in Exhibit 7A and is briefly summarized here. They analyzed major and trace constituents in six streams in the Yampa River drainage. The data revealed that overall stream chemistry was characterized by saturation of common carbonate minerals such as calcium, magnesium, iron, manganese and lead. They also determined that the solubility of the carbonate materials was a major control on the absolute and relative concentrations of calcium, magnesium, iron, manganese and lead. The mean concentrations in the semi-arid watersheds of Taylor Creek and Wilson Creek were significantly higher than those from the more humid watersheds in the Upper Yampa River Basin. Trace metals, however, were not significantly different as a function of climate or other variables. The study also produced linear regression estimators useful in predicting total dissolved solids and other major ion concentrations as a function of specific conductivity, which is more easily measured. Results of the linear regressions and statistical comparisons of the mean values showed that Taylor Creek and Wilson Creek were different for the major concentrations. Goodspring Creek was not included in the analysis because of its alluviahcolluvial valley floor characteristics. These differences, however, are not inhibitory to the overall regression process and substantiate the conclusion of highly variable water quality within the Colowyo Mine area. The regressions are further valuable for future predictions of the major ions in each basin as a function of possible mine disturbances. Specific conductivity measurements can be taken in the field instead of exhaustive laboratory analysis and the major ions predicted with reliability. The mean values of the main ions in the two watersheds showed that the major cations were dominated by calcium, magnesium and sodium with low levels of potassium. Major anions were dominated by bicarbonate and sulfate. Chloride levels were low in Taylor Creek, but were much higher in Wilson Creek. Specific conductance was high. This information is in accordance with past studies and substantiates all conclusions made in previous reports. Heavy metals were also analyzed. Predictive capabilities were not as accurate but the mean values reported showed consistence with other studies. The results were reported as total recoverable metals in micrograms per liter (ug/1). Lead and cadmium were extremely low and the values were near or at the detection limits for Atomic Absorption Spectrophotometry. Zinc levels were moderate, around 10 ug/l, while iron and manganese were higher and more variable. Iron values for Taylor Creek and Wilson Creek were 40 ug/1 and 27 ug/1, respectively. Manganese levels were 7 ug/1 for Taylor Creek and 65 ug/1 for Wilson Creek. The reason for the higher manganese levels in Wilson Creek is not explained. Rule 2 Permits 2.04.7-21 Revision Date: 6/23/08 Revision No.: MR-91