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1999 0.005 cfa <br />• 1998 0.165 cfa <br />1997 0.095 cfs <br />1996 0.065 cf9 <br />The spring runoff this yeaz was the lowest on record. Review of this site's TDS plot <br />indicates an increaa inq trend. Baseline data for this site (W553) has been provided just <br />prior to the TDS plot. <br />- Surface Water Site SW-SZW-FG4 (WSSF3). This site is situated on Saga Creak downstream <br />o£ the ampacis from the Seneca II-W Mine (and also SCC's Yoaet Mine). Monitoring of thas <br />site commenced in September 1990. The peak flow this yeaz was lower than that observed in <br />the prior four years. This site displays a decreasing TDS trend. <br />The Seneca II-W PHC predicts an irrtga tion season average TDS value of 465 mg/1 on Sage <br />Creek, chile a value of 665 mg/1 was observed. Data from Site SW-S2W-FG3 IYSSFl) was <br />originally used in the P8C for calculating impacts to Sage Creek. This VSGS site existed <br />in the early 1980's on Sage Creek upstream of the old gage Creek Reservoir and adjacent to <br />the Yoaat Mine. For use rn this AHR evaluation, data from Site SW-S2W-FG4 (WSS F3) is <br />• used. From 1991 to 1995 (prior to the first drschaxge fzom MPDES 009), Site FG4 had a <br />June-September average TDS value of 629 mq/1 and a June-September average flow of 0.9148 <br />cfs 11.8194 ac-ft/day). Suba[i toting these values into the formulas on page 51, Tab 17 <br />(PtlC), of the Seneca II-W PAP, on gets: <br />Sage Creek premi Wing: Load = 0.9148 cfa % 629 mg/1 X 0.0027 (correction factor) <br />= 1.5536 tons/day <br />Saga Croak poatmining: DSC = 1.5536 + 0.034 <br />11.8144 + 0.0055) X 0.00136 <br />= 6d1.4 mg/1 TDS <br />In other words, the predicted postminrnq TDS value at Site FG4 is 641 mg/1 (not 465 mg/1). <br />The 665 mg/1 value observed this year in only 49 greater thm the predicted value. Since <br />the maximum TDS value observed during the same time frame at NPDES 009 was only 630 mg/1, <br />and since no other mine related disChazgee aze present at Si to FG4, it can be concluded <br />that the 665 vg/1 value ie a result of natural year-to-year variability. <br />rin s. Spring data may be found after surface water data in Appendix E. Data provided <br />are a water quality report for the yeaz, historic flow measurements, baseline rater <br />• <br />IS <br />