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• eater parameter list, Table 10 (Appendix A) during April, June, and September. Seven <br />springs are monitored ai Seneca 11-W: S-1, S-5, 5-23, 5-41, 5-45, 5-46 end 5-47. They <br />are monitored for flow, field parameters, and the surface water parameter list <br />semiannually (once in April-June, then again in September-November). A summary of surface <br />eater monitoring sites end sampling frequencies is presented in Table 11 (Appendix A). <br />All surface water data is found in Appendix E. Discharge monitoring reports for NPDES <br />005, 006 and 009 can be found in Appendix F. Data for each site begins with a flow <br />hydrograph of all historic data (plus an annual hydrograph for NPDES sites), followed by a <br />statistical summary of eater quality data for the current eater year, and then a listing <br />of individual eater quality and quantity data for the current water year. Percent <br />milliequivalent values are presented in Tables 12 and 13 (Appendix A). All data prior to <br />1990 has been averaged together to provide the baseline (i.e., premining) conditions that <br />existed. In addition, the range of total dissolved solids (TDS) that existed prior to <br />mining is also given. Since mining began in 1990, that data and all subsequent data are <br />listed separately. The following discussion of water quality will limit itself to a <br />description of major ions. A separate section, Comparison of Surface Water Quality to <br />• (later Use Standards, will fist those samples that exceed eater use standards. Lab samples <br />are handled in a matter identical to what was discussed earlier in [he ground eater <br />section. For the sake of brevity, the SW-S2Y- prefix that precedes all surface water site <br />names will often be dropped throughout this report. As an example, Site SN-52w-FG1 will <br />be referred to as Site FG1. <br />Surface Na[er Site SN-S2V-FG2. This site is located on Natering Trough Gulch and is <br />located upstream of mining. This site was dropped from the monitoring program in <br />November, 1985 and was picked up again with the revised monitoring program in April, 1987. <br />Review of its hydrograph shoos the highest peak flow observed since 1985. Samples at this <br />site display a LaMg-SO4HC03 type water with an average TDS value of 945 mg/l in 1993. <br />This value is higher than the baseline average of 750 mg/l, but falls within the baseline <br />range of 375 to 1,180 mg/l. <br />Surface hater Site SY-52L1-SG 7- This site is located on Hubberson Gulch upstream of the <br />confluence of mine discharges contained in 006 Gulch. As with Site FG2, its purpose is to <br />provide undisturbed eater quality data. Monitoring here began in April, 1987. Review of <br />• its hydrograph shows typical seasonal variation due to snowpack runoff in the spring. <br />Samples at [his site display a MgLa-HC03SO4 type eater with en average TDS value of 569 <br />9 <br />