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The change is happening, but the higher concentrations are found at TR-1.5 (supposed to be upgradient station ... upstream ojmintng activity). AHR attributes that to old underground mine upstream. The situation that results from this is that water w/similar dissolved solids contents from spoils (represented by WR-1 well) is being added to this high-TDS groundwater found at TR-1.5. /gnoring the details of mixing, this will probably produce higher TDS contents as waters mix. This high TDS water will probably migrate down to downstream stations TR-3 and 4 in next several years. Because of this influx of high TDS water from upstream, predictions for groundwater TDS content will probably be exceeded in the future. predicted post-mining groundwater TDS of 2828 at West Ridge (p. 2.5-101) This concentration is exceeded as demonstrated by water from well WR-1; last four years WR-1 water has ranged from 3000 to > 4000 mg/1 TDS. Another important issue is the validity of the data, particularly the reported TDS data. These data do not fit the analytical data from the same site. For example, water from spring 1 has reported TDS of 3200 while combined dissolved constituents from the full suite analysis total 4054 mg/1, indicating that reported TDS value is low. A simple extrapolation yields 25% higher total of dissolved salts entering Trout Creek from groundwater beneath West Ridge than predicted in the permit. We request that the appropriate portion of the permit be amended to reflect these values, and that an explanation of the inconsistencies between TDS and summed individual components be provided. The value of 2,828 mg/1 TDS provided in the permit application represents the TDS concentration of flow from all sources on West Ridge, ground water and surface water. This value is more appropriately compazed to the annual average TDS value occumng at CDPS point #007 which reflects the contribution of both ground water and surface water from West Ridge to Trout Creek.. The average annual TDS concentration observed or calculated for #007 over the past 17 years for that site is 3,247 mg/I. As such the predicted value and observed value differ by less than 15%. Appendix 2.5-A has been revised [o reflect this difference. The inconsistency noted in the 1996 AHR between the TDS and summed individual components results from the reported TDS values being derived from "field" measurements, while the summed components were analytically derived by an independent laboratory. It is probable that the TDS meter used in the field was not properly calibrated prior to use and thus provided an erroneous reading. The TDS "field" values were reported without verifying their consistency with the laboratory's analytically derived TDS values. Future TDS values measured in the field will be compazed to analytical values for consistency with analytical values being reported when performed. It should be noted that all TDS values used in Appendix 2.5-A were analytically derived values.