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0.15 feet. The potential two percent increase Sn TDS in the Saqe Creek alluvium will probably not be measurable and will have no adverse effects on the existing water uses. • Premrninq Saqe Creek alluvial water chemistry analyzed at updralnage USGS xells indicates the alluvial water is marginal to uns ul [able for stock and irrigation use. PotenClal Impact of Replaced Spoil on Surface Water Quality. The following impact analyses include an assessment of Seneca II-W spoil water discharge on Dry Creek tributaries, Dry Creek, a Sage Creek tributary, and Sage Creek stream water quality. The previously-referenced equations presented by Ferreira 11984) were utilized to calculate percent increases in TDS and chemical load in tons/day. Table 17-19 lists the spoil and stream reach flow and TDS values used in the impact assessments. The following equations present [he pre mining and postmining chemical load and TDS concentration changes as a result of the spoil aquifer dlscha rging into Dry and Sage Creeks. Dry Creek Drainage Premining: ~ Hubberson Gulch L = 0.605 x BB2 x 0.0027 = 1.44 cons/day Watering Trough Gulch L = 0.136 x 772 x 0.0027 = 0.28 tons/day Dry Creek L = 1.5 x 1098 x 0.0027 = 4.24 tons/day • Dry Creek Dra Snage postmining: Hubberson Gulch DSC = 9.16 + 1.44 z 2193 mg/1 (1498 TDS 11.2 + 0.6781 x 0.001361 increase) Hubberson Gulch L = 0.947 x 2193 x 0.0027 = 5.61 tons/day (2908 tonnage increase) Waterlog Trough C,ulch DSC = 5.61 + .2B ~ 2024 mg/1 (938 TDS Increase + Hubberson Gulch I1. B7 + 0.27( x 0.00136 over SGS due to 006 spoil dlscha cgel Watering Trough Gulch L = 1.08 x 2024 x 0.0027 = 5.9 tons/day (398 tonnage + Hubberson Gulch increase over SG5 due to 006 spoil dlscha rge) Cumulative Dry Creek Drainage Pos[mi ping: Dry Creek + 005 Tcib DSC = 5.9 + 1.06 = 2245 mg/1 11148 TDS increase 2.14 + 0.1731 x 0.00136 over SG5) D[y Creek + 005 Trib L = 1 .167 x 2245 x 0.0027 7. 07 tons/day 1678 tonnage increase over • SG5) 99