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One well monitors the 005 Gulch alluvium (tributary to Dry Creek). This <br />well, WDAL11, is normally dry. <br />Three wells monitor the Sage Creek alluvium. Well WSAL12, located on <br />Sage Creek adjacent to Surface Water Site SW-S2-FG4 (WSSF3), is <br />downstream of all mine discharges on Sage Creek. TDS values at this well <br />had been increasing since it was drilled in 1990. Well WSAL13 is located <br />below NPDES 009 on the northern Sage Creek tributary (this NPDES site, <br />constructed in 1991, started flowing for the first time ever in 1996). <br />This well displayed an increasing TDS trend. However, since October <br />2001, there has not been enough water to sample in this well. Well <br />WSAL14 exists on the southern Sage Creek tributary below NPDES 015 <br />(constructed in August 1999, first flow February, 2000). Monitoring was <br />resumed at this well in May 1995 after being discontinued in October <br />1995. It displays a stable TDS trend. <br />In the Probable Hydrologic Consequences section (PHC, Tab 17) of the <br />. Seneca II-W PAP, predictions were made for the May-September average TDS <br />values at various alluvial wells. In the Hubberson Gulch alluvium at <br />Well WHAL7-2, a value of 1299 mg/1 was predicted, while a value of 1705 <br />mg/1 was observed this year. In the 006 Gulch alluvium at Well WHAL10, a <br />value of 3394 mg/1 was predicted, while a value of 2990 mg/1 was <br />observed this year. In the Sage Creek alluvium at Well WSAL12, a value <br />of 972 mg/1 was predicted, while a value of 735 mg/1 was observed this <br />year. <br />The May-September average TDS value measured this year at Well WHAL?-2 <br />was 1705 mg/1, while the predicted value was 1299 mg/1. The value <br />observed was determined gravimetrically (i.e., dry a water sample and <br />weigh the residue). According to Hem (1989, pg. 157), ... it is not <br />uncommon for water high in calcium and sulfate concentrations to yield a <br />residue after drying an hour at 180°C that exceeds the computed <br />dissolved solids by several hundred milligrams per liter" and also, "In <br />many instances, especially if the concentration is greater than 1000 <br />~~ mg/1, the calculated dissolved-solids value may be preferable to the <br />residue-on-evaporation value". The calculated dissolved solids value is <br />7 <br />