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2) terms associated with predicted values are not the same as terms associated with monitoring data. In regard to the first point, Rule 2.05.6(3) requires that the permit include a determination of the probable hydrologic consequences of proposed mining activities within and adjacent to the permit area. P & M is apparently contending that the Edna Mine permit cannot be used to determine the hydrologic consequences of mining. In that case, the PHC in the permit will need to be revised, as per item l.c of the Division's January 4, 1993 letter. Short and long term impacts on ground and surface water quality need to be addressed so the Division can make determinations regarding hydrologic impacts, as required by Rule 2.07.6(2)(c). In regard to the second point, the fact that different methodologies are used to derive predicted and observed values does not mean the terms of those values are different. Predicted TDS values can be compared to observed TDS values. If the term "annual average" is not accurate, P & M should explain or change the term in the PHC, as mentioned in the Division's January 4, 1993 letter (please refer to item l.i.). Page 2.5-A-11 also states that statistically significant differences between predicted and observed values cannot be made because the predicted values have no error terms associated with them. Comparison of sample data to set values using statistical techniques is a common practice. Monitoring data can be compared to predicted water quality values while accounting for desired levels of statistical confidence. This was, in fact, done several times in the proposed revision of appendix 2.5-A. I have enclosed a copy of our January 4, 1993 letter for your convenience in responding to these comments. Should you have any questions or need additional information, please contact me. Sincerely, QI,Fh Susan L Bur aier Environmental Protection Specialist Enclosure c: Barbara L Pavlik, CDMG, w/out enclosure SLB\091493.WP ever n ontare 5 cto er ,