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Section 780.21(c) Continued. <br />Ion Balance of Surface Water <br />Chemical analyses of surface water samples taken from undisturbed and <br />affected areas for the baseline data collection program indicate that <br />operations may effect a change in the ion balance of water which <br />discharges from the proposed permit area. To document this change, <br />data on major ion constituent concentrations were collected from <br />sample sites currently receiving drainage from undisturbed (baseline) <br />and disturbed (affected) areas in the proposed permit area. The data <br />from several sites were assimilated and reduced in Table 14, Kerr <br />Mine Area Surface Water Quality Data. Average concentrations of <br />major ions for each sample site were converted from milligrams per <br />liter to percent milli-equivalents per liter to determine the <br />dominant chemical types of water present. These values were plotted <br />on trilinear diagrams in figure 9, Kerr Baseline Surface Water <br />Quality, and figure 24, Kerr Affected Surface Water Quality. The <br />• sample sites are identified on the diagrams and shown on Map 16a, <br />Kerr Mine Area Surface Water Hydrology. The trend shown in the <br />diagrams is a change from calcium-bicarbonate type baseline water to <br />sodium-bicarbonate and magnesium-sulfate type affected water. The <br />sodium-bicarbonate and magnesium-sulfate components are attributed to <br />disturbance of watersheds due to mining. The runoff flows over <br />disturbed ground which presumably contains more soluble sodium, <br />magnesium and sulfate elements than undisturbed ground. It should be <br />noted that the sample sites containing higher percent concentrations <br />of magnesium-sulfate are located in drainages below disturbed and <br />unreclaimed areas. The effects of reclamation in mitigating changes <br />in water type could not be determined from the baseline program data. <br />The change -in water type in mined areas will apparently have an _ <br />effect only on that reach of the receiving streams which is adjacent <br />to and just downstream from the active mining area. <br />The abandoned Sudduth Mine in Township 9N, Range 78W, Section 15, is <br />currently discharging water affected by previous mining through <br />780-126 aaaR Revised - January, 1991 <br />