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RULE 2 PERMITS <br />The data for the period 1974-1975 collected by Colowyo for the major ion concentrations, turbidity, <br />dissolved solids, iron, and pH for the seven sampling locations along Wilson Creek, Taylor Creek and <br />Goodspring Creek are presented in Tables 2.04.7-17, 2.04.7-18 and 2.04.7-19. For all constituents except <br />chloride, the concentrations varied only slightly among the stations during any one month. Also <br />concentrations above and below the mine were not appreciably different. However, the Wilson Creek <br />stations consistently showed chloride concentrations five to ten times higher than other stations. Chloride <br />is usually absent in groundwater seepage but can be present in high concentrations in mineral springs. <br />Since such springs have not been reported along Wilson Creek, some other source may be causing these <br />high levels. Since the geology of the three drainage basins is very similar, water quality differences may <br />relate to agricultural or other disturbances in the area. Additionally, the natural slumping of bank areas <br />above the USGS gage on Wilson Creek may significantly impact the results of this parameter. <br />Dissolved solids concentrations showed incremental increases of 40 mg/1 to 50 mg/1 per mile of flow. <br />These increases represented the inflow of total dissolved solids from groundwater seepage, agricultural <br />drainage, dissolving elements found in the streambed, and the concentrating effect of evaporation of the <br />stream water. <br />Seasonal water quality variations in the streams were evident in the sample results. As streamflow <br />decreased to the baseflow period of fall and winter, the stream source changed from mainly surface runoff <br />caused by snowmelt and rainfall to mainly groundwater seepage. This change is reflected by changes in <br />water quality. Alkalinity, which is a measure of dissolved carbonate and bicarbonate ions, showed <br />somewhat of a direct relation to the proportion of surface runoff and decreased in the fall. Sulfates, which <br />are the product of the oxidation of sulfur minerals and are typically found in groundwater, increased in the <br />fall. These changes usually occurred as surface runoff decreased, rather than as groundwater flow <br />increased. Magnesium and sodium also showed seasonal fluctuations, with magnesium decreasing and <br />sodium increasing in the fall. Chloride concentrations decreased in the fall in a manner similar to other <br />elements, but with somewhat different timing. <br />Iron was present in normal quantities. Since no deposits of "iron boy" were observed along any of the <br />streams, acid drainage problems are not evident or expected. All the cadmium, lead, chromium, and <br />arsenic results were below their respective toxic thresholds of 0.01 mg/l, 0.03 mg/l, 0.05 mg/l, and 1 <br />mg/1 (NAS, 1972). In addition, all the mercury and selenium analyses were below their toxic thresholds <br />of 0.00005 mg/1 and 0.23 mg/1, respectively, as indicated by the presence of aquatic life. Toxicities of <br />zinc and copper vary widely in water of different hardness. Laboratory experiments and field bioassays <br />have shown high levels of calcium, such as those found in these drainages, to inhibit the toxicity of these <br />metals. Based on hardness and alkalinity the waters in these drainages are not toxic to aquatic life. No <br />unusual water quality constituents were detected by this sampling program. <br />Sampling for water quality constituents has continued since the 1974-1975 data collection period. The <br />USGS has collected data at Taylor Creek, Wilson Creek and Goodspring Creek for a host of water quality <br />parameters as a part of the continuing EMRIA Program. Colowyo has also collected data for Taylor <br />Creek and Goodspring Creek for the period 1978 to present. These data continue to reflect the high <br />variability by month of specific conductance, total dissolved solids, total suspended solids and the other <br />constituents of concern. Table 2.04.7-20 is a comparison of USGS and Colowyo data. The raw data from <br />which these calculations were derived are included in Exhibit 7A. The data in Table 2.04.7-20 are <br />revealing in that the USGS effort has been much more intensive than the Colowyo effort, but the results <br />are quite similar. <br />Comparisons of mean values indicate that little difference exists between each program for similar <br />stations. These mean values show no significant differences except for the total suspended solids data at <br />Taylor Creek. Colowyo's data shows much lower mean values than does the USGS data. This is due <br />Rule 2 Permits 2.04.7-20 Revision Date: 6/23/08 <br />Revision No.: MR-91