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<br />obtained prior to ground water pumpage (water well 90-1 ), and 1991-1998 mining activities. <br />The data shown on the tables present a historical summary of water quality (WO) data. <br />The (WQ) results for wells immediately down-gradient from the injection/recovery well field <br />indicate three distinct water quality zones. The Perched aquifer is low in TDS (total <br />dissolved solids), conductivity, fluoride, SAR (sodium absorption ratio) and moderate to <br />high in sulfate and pH. The A-Groove and B-Groove aquifers are similar in water quality <br />with moderate TDS, conductivity, SAR, but high fluoride. Although similar, the B-Groove <br />aquifer generally has slightly higher levels of TDS, conductivity, SAR and fluoride. <br />The Dissolution Surface aquifer is characterized by high TDS, conductivity, SAR, <br />• magnesium, potassium but moderate pH, and until 1993 moderate fluoride levels. In late <br />1993, a significant increase in the concentration of fluoride was noted in the down-dip <br />Dissolution well. Figure 6-2 illustrates fluoride results of WO sampling. Sodium and boron <br />WO results indicated a similar increase but at a lesser rate. Alkalinity, bicarbonate and <br />TDS data indicated an increase late in 1993. See Figure 6-3 for illustration of bicarbonate <br />results. Other WQ parameters indicated increased concentrations in late 1993 but lower <br />than period of record highs, i.e. magnesium, chloride and hardness are examples. Figure <br />6-4 illustrates chloride results. In late 1993, WO changed significantly and was <br />characteristic of a mixture with mine water. Most WO parameters peaked in 1994 and <br />declined in late 1994 to mid 1995 as a result of recompletion water (July 1994) from the A- <br />f~ <br />45 <br />