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South San Joaquin Irrigation District <br /> DRAFT Lead Assessment&Abatement Work Plan April 9, 2097 <br /> The weighted average lead canal water concentration was calculated and compared to relevant and <br /> other regulatory agency objectives as shown in Table 2 below: <br /> Table 2. Summary of Regulatory Agency Objectives for Lead in Water <br /> Regulatory Agency Objectives for Lead Threshold (µg/L) <br /> Agricultural Water Quality Goal (Food &Ag. Org. of United <br /> Nations) 5,U0© <br /> Cal/EPA Primary Maximum Contaminant Level (MCL) 15 <br /> Cal/EPA Cancer Potency Factor as a drinking water level <br /> (1:1,000,000 Incremental Cancer Risk) 4.1 <br /> Cal/EPA No Significant Risk Level (1.100,000 Cancer Risk) 7.5 <br /> Cal/EPA Maximum Allowable Dose Level (MADL)for <br /> Reproductive Toxicity 0.25 <br /> Note: Bold values in the table indicate that the threshold value is not exceeded by the estimated weighted <br /> average lead concentration. <br /> Because water in the SSJID canal is used for agricultural purposes, the most relevant threshold is <br /> the Agricultural Water Quality Goal. Because the SSJID canal water is not used as a drinking water <br /> source, the other regulatory agency objectives are not directly relevant. However, they do serve as <br /> a benchmark regarding potential risk and are useful in expressing that the amount of soluble lead is <br /> not expected to pose an unacceptable human health risk. Exposure levels and discharges to <br /> drinking water sources that are above the MADL may require compliance with Proposition 65, such <br /> as posting warning signs. However, since the SSJID canal water is not used as a drinking water <br /> source, the MADL is not relevant. <br /> Based on available data, sufficient information exists to demonstrate that adverse impacts to human <br /> health due to lead pellets in the canal during the irrigation season are not expected. <br /> Page 9 Blankinship & Associates , Inc . <br />