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AMW-7 and AMW-14; hexavalent chromium at AMW-14; magnesium at AMW-6, AMW-7, and AMW-14; nitrate at AMW-2, AMW-6, AMW-7, and AMW-14; potassium at AMW-14; sodium at AMW-14; field specific conductance at AMW-2, AMW-6, and AMW-7; strontium at AMW-6 and AMW-14; sulfate at AMW-7, AMW-13, AMW-14; TDS at AMW-2, AMW-6 and AMW-7; and field turbidity at AMW-12. Given that bicarbonate alkalinity, nitrate, TDS, and field specific conductance exhibit significant increasing trends at upgradient well AMW-2, the increasing trends for these constituents at downgradient wells are likely due to ongoing changes in the natural groundwater geochemistry at the site. Mann -Kendall / Sen's Slope analysis identified significant decreasing statistical trends for the following inorganic constituents: calcium at AMW-12, chloride at AMW-12 and AMW-13, hexavalent chromium at AMW-7, nitrate at AMW-13, potassium at AMW-7, strontium at AMW- 7, and field turbidity at AMW-2. Mann -Kendall / Sen's Slope analysis did not identify any significant increasing statistical trends for VOCs. Mann -Kendall / Sen's Slope analysis identified significant decreasing statistical trends for tetrachloroethene at AMW-14 and trichloroethene at AMW-13. The fourth quarter 2012 barium concentration at AMW-12 (0.23 mg/L) is within the range of concentrations observed at that well since the beginning of monitoring in May 1995 (0.14 to 0.28 mg/L). As discussed above, barium at AMW-12 does not exhibit a significant increasing statistical trend. A Wilcoxon rank -sum test comparing the barium data at upgradient well AMW- 2 to the data at AMW-12 (a = 0.05) indicates that the barium data at AMW-12 are statistically distinct from those at the upgradient well. The Wilcoxon rank sum plot is presented in Appendix E. The presence of stable barium concentrations at AMW-12 that are statistically distinct from upgradient concentrations indicates that the concentration limit exceedance for barium at AMW- 12 in the fourth quarter 2012 is likely due to spatial variation in the natural groundwater geochemistry at the site. The fourth quarter 2012 barium concentration at AMW-13 (0.26 mg/L) is within the range of concentrations observed at that well since the beginning of monitoring in May 1995 (0.24 to 0.34 mg/L). As discussed above, barium at AMW-13 does not exhibit a significant increasing statistical trend. A Wilcoxon rank -sum test comparing the barium data at upgradient well AMW- 2 to the data at AMW-13 (a = 0.05) indicates that the barium data at AMW-13 are statistically distinct from those at the upgradient well. The Wilcoxon rank sum plot is presented in Appendix E. The presence of stable barium concentrations at AMW-13 that are statistically distinct from upgradient concentrations indicates that the concentration limit exceedance for barium at AMW- 13 in the fourth quarter 2012 is likely due to spatial variation in the natural groundwater geochemistry at the site. The fourth quarter 2012 barium concentration at AMW-14 (0.27 mg/L) is within the range of concentrations observed at that well since the beginning of monitoring in July 1995 (0.093 to 0.3 mg/L). As discussed above, barium at AMW-14 exhibits a significant increasing statistical trend. The increasing trend is not observed when the data are limited to the period of November 2009 to November 2012. A Wilcoxon rank -sum test comparing the July 1995 to August 2009 barium data at AMW-14 to the November 2009 to November 2012 data (a = 0.05) indicates that these periods are statistically distinct. The Wilcoxon rank sum plot is presented in Appendix E. This indicates that the significant increasing statistical trend in barium at AMW-14 may be due to a