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.-5- data submittal (submitted to the Division in a letter dated October 12, 1983). This data has been summarized in Tables 6 and 7 of the annual report. Field data for the Trout Creek Sandstone has been cumulatively summarized in Table 5 of the annual report. From the available data, it appears that the quality of Trout Creek Sandstone water has not varied appreciably over the period of record. Mean Total Dissolved Solids (TDS) for the period from 3/81 to 6/83 was 805 mg/L with a range in concentration from 595 to 1010 mg/L (Table_fi,.). Mean TDS for 198~as-832 .mg/L (Table 7). The mean pH is 7.95~ith a range from 7.00 to 8.75,(Table 6). The j water is Na-HC03 in prevalent chemical type and the water temperature is somewhat higher than other ground water in the mine area. Mean water temperature in 1983 was 17.20 C (Table 5). Ground water from other bedrock and alluvial sources was generally in the range from 11 to 13°C. Zinc concentration is also somewhat higher than other bedrock ground water sources in the area. 1.2.2 Middle Sandstone The three wells completed in the Middle Sandstone (Wells TR-4, TR-7A and 81-01) were sampled quarterly for field parameters (pH, conductivity, temperature) and once during 1983 for full suite analysis. A summary of the 1983 field data for these wells is presented in Table 5. A summary of the 1983 full suite parameters is contained in Table 9. The cumulative summary of water quality data for the Middle Sandstone since monitoring began in 1981 is presented in Table 8. A degradation in water quality is often associated with dewatering of an aquifer; however, upon comparison of Tables 8 and 9, it appears that no significant changes in water quality are occurring in spite of declining water levels in the aquifer. The prevalent chemical character is Na-HC03, C03 with a pH range over the period of record from 6.5 to 10.3 (Table 8) and a mean pH of 8.59 (which may explain the presence of the C03 anion in the analyses). Mean electrical conductivity over the period of record is 490 umhos/cm (Table 8), which is not significantly different from the mean value for 1983 of 570 umhos/cm (Table 9). 1.2.3 Twentymile Sandstone During 1983, 15 water samples were analyzed for field parameters from the two wells completed in the Twentymile Sandstone (Well 259 and No. 9 Mine Well). A summary of the field parameters is presented in Table 5. A summary of the 1983 full suite analyses is given in Table 11 and a cumulative summary of water quality data from 3/81 through 6/83 is given in Table 10.