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increase the creek's TDS by 14 mg/1, from 557 mg/1 to 571 mg/1. The increase would be a small <br />fraction of 14 mg/1 during irrigation season when streamflow typically is an order of magnitude <br />]azger than during low-flow. <br />Impacts to Alluvial Valley Floors (AVFs) -Regrading and revegetation has remediated the impacts <br />of the physical disruption caused to the Stollsteimer Creek AVF by Kaiser's mining operation. The <br />revegetation success standazds set for the Stollsteimer Creek AVF were based on what is necessary <br />for the AVF to regain its pre-mining agricultural productivity. As previously discussed in this <br />Findings dccument, Kaiser has successfully achieved the revegetation standazds on the AVF; <br />therefore, the pre-mining productivity of the AVF has been restored. Sustained stream flows in <br />Stollsteimer Creek since Kaiser's operations began indicate Kaiser has not depleted the supply of <br />water to the AVF. Although post-mining electroconductivity values of surface and alluvial waters in <br />Stollsteimer Creek exceed the material damage suspect levels for alluvial valley floors, the post- <br />miningvalues donot exceed the baseline values (see following table). This comparison indicates the <br />Chimney Rock Mine has not caused material damage to the waters of the Stollsteimer Creek AVF. <br />Comparison of observed EC values to material damage suspect EC values during October <br />through January in Stollsteimer Creek and in AVF monitoring well W-5 <br />Observed baseline <br />Material mean 1980-1 <br />damage Observed post-mining mean, <br />suspect level 1985 - 2002 <br />Surface water in <br />Stollsteimer Creek (baseline <br />site S-1, post-mining site S- 700 942 (n=3) 801 (n=15) <br />2) (electroconductivity in <br />micromkoslcm) <br />Alluvial water well W-5 on <br />AVF (electroconductivity in 1,050 993 (n=3) 972 (n=10) <br />micromhos/cm) <br />Comparison of Observed Impacts to Predicted Impacts -All of the previously described <br />hydrologic impacts are consistent with those predicted in the Probable Hydrologic Consequences <br />(PHC) section ofKaiser's permit application and the Division's Piedra River Cumulative Hydrologic <br />Impact Assessment. The PHC predicted the formation of spoil leachate, the dischazge of the <br />leachate, and possible loading of stream water with salts. Kaiser's annual hydrology reports have <br />identified monitoring data that may indicate 3eachate influence. The Piedra River Cumulative <br />Hydrologic Impact Assessment predicted Stollsteimer Creek would experience increased salt content <br />of less than 1 %, consistent with monitoring data. <br />to <br />