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The Sage Creek "system" is actually exceeding the TDS loading predicted. Although concentrations measured have displayed a wide range of values, the high has reached 7l0 mg/l whereas the predicted maximum for post-mining water is 465 mg/l. Groundwater The alluvial groundwater up-gradient of mine influence in the Hubberson Gulch "system" has ranged near 700 mg/l during the years of monitoring. The "006 tributary" has actually decreased in TDS content in the last 2 years to azound 2000 mg/l from a high of 2300 mg/I. The prediction is 3400 mg/I. Of course, it remains to be seen how the trends proceed from 1997 into the future. The Sage Creek alluvial aquifer system has also remained at concentrations lower than predicted in the PHC. The alluvial water down-gradient of the area of influence (down-gradient of the confluence with the 009 tributary) appears to have increased steadily in TDS- content from -500 mg/I in 1990 to -700 mg/I in 1996. The predicted maximum concentration in the PHC is 972 mg/l, so the water in Sage Creek is on its way. It should be noted, though, the alluvial groundwater in the Sage Creek alluvium is monitored at several locations up the creek from the 006 tributary as far as 4 miles. The TDS concentrations at these locations have varied widely from site to site, reaching as high as 1700 mg/1 at site WSAL8, more than 3 miles upstream from the tributary. This indicates that the quality of water reaching the down-gradient monitoring point may be ofwidely-varying quality through the years, with effects not necessarily directly attributable to the inflow of water from the 009 tributary. In general, the AHR indicates that conditions aze generally within the bounds predicted in the permit application. Please call if you have any questions. Sincerely, s~ ~~ Erica S. Crosby Environmental Protection Specialist c:\esc\seneca2w\980105