Laserfiche WebLink
Stream TDS (mean) TDS (range) <br /> (mg/L) (mg/L) <br /> Upper Grassy Creek: YSGF5 973 736 - 1170 <br /> Lower Grassy Creek: YSG5 2725 1260 - 3860 <br /> Sage Creek: YSS2 1617 694 - 3240 <br /> The average TDS concentrations in the receiving streams exhibit general agreement with the <br /> predicted values. Both the Sage Creek and Upper Grassy Creek monitoring points exhibit <br /> average TDS concentrations below the predicted values. Although YSG5 exhibits TDS <br /> concentrations that are above the predicted value for lower Grassy Creek its important to <br /> remember that YSG5 is located downstream of Scotchmans Gulch and the predicted <br /> concentrations did not consider contributions from Scotchmans Gulch. <br /> The PHC predicted that impacts from Yoast Mine spoil discharges to Annand Draw/Scotchmans <br /> Gulch/Grassy Creek and Sage Creek would be of moderately long duration, but impacts would <br /> not be significant enough to alter their potential use. Streamflow is limited in both reaches and <br /> remains insufficient to rely on for flood irrigation practices (see Tab 7, Hydrologic Description). <br /> Streamflow in Grassy Creek was determined to be insufficient for drinking water, agricultural <br /> water, or livestock water, while stream flow in Annand Draw and Sage Creek were determined <br /> to be sufficient for livestock purposes. The TDS concentrations measured at the stream points <br /> above indicate that the water quality remains adequate for livestock purposes. As described in <br /> Section B, the water quality at both the Grassy Creek and Sage Creek stream points meets the <br /> WQCC Regulation 31 Agricultural Use water quality standards. <br /> Impacts from runoff of the reclaimed mine areas and sediment ponds were projected to be of <br /> minimal significance. This is in agreement with the water quality observed in the receiving <br /> stream and at the NPDES outfalls (see Section B and C above). <br /> SL-7 - 46 <br />