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Musco Family Olive Company - 12 - 12'December 2006 To further illustrate the point, the data set has been plotted as "Time Series Plots" for the constituents listed below: • TDS • Calcium • Sodium • Magnesium • Sulfate • Chloride • Bicarbonate The "Time Series Plots" for TDS and general minerals are presented in Appendices C and D, respectively, for the Regional Well, and shallow wells MW-1, MW-3, MW-5, MW-13 through MW-17. As shown in the plot for the Regional Well, groundwater in this well is sulfate dominant. Chloride and sodium are stable at concentrations below the interim background groundwater concentration limits of 601 and 591 mg/L. Bicarbonate is also stable and shows no increasing trend. Calcium and Magnesium are detectable at low concentrations and stable. Staff believes the Regional Well groundwater data is more appropriate for the development of interim background groundwater concentrations for the deep zone due to its location outside the impact zone and its well construction. Furthermore, the use of the Production Well data as interim background groundwater concentrations is inappropriate due to the well depth, unknown pump depth, and unknown screen intervals. Consequently, it is unknown what zone the Production Well is capturing groundwater from_ When the Regional Well is compared to wells located in the upland, mid-slope, and lowland spray irrigation fields and adjacent to the Reservoir or 1 million gallon pond, apparent geochemical differences standout. Well MW-1 Well MW-1 is near the southern most boundary of Field 95, could be considered an up-gradient well possibly representative of background groundwater conditions. However, when the CDCs are plotted on the trend analysis it is evident that chloride and sodium concentrations have increased since 2002. The Time Series Plot of TDS indicates a sharp increase between early 2002 and late 2003 when concentrations equilibrate and stabilize over time. TDS has increased from 690 mg/L (April 2002) to 1,400 mg/L (June 2006). The same pattern for chloride and sodium are also seen in their respective plots. The increase of TDS, chloride, and sodium still remain below the interim water quality standard. This is likely due to continued mixing with groundwater outside the impact zone. Musco has been spray irrigating Field 95 since 1991. Well MW-13 Well MW-13 is down-gradient of well MW-1 in Field 95. It is located in a topographic low next to a drain inlet that conveys wastewater under the railroad tracks to the Reservoir. Well MW-13 has been dry since mid 2005, yet the earlier data indicates groundwater in the vicinity of well MW-13 is impacted by elevated concentrations of chloride, sodium, and bicarbonate. The chloride trend plot for well MW-13 varies significantly between sampling events conducted