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L 1�, <br /> September 21,2005 <br /> NOA Project Number: E05104A <br /> 2.3 Current and Future On-Site Ground Water Uses <br /> LNo domestic water well exists on the property.The existing residence on the south portion of the <br /> subject property shares a domestic well that is located on the adjacent property to the east. It is Z 3) <br /> proposed that the existing residence on the subject property will be demolished. Each parcel will <br /> V utilize a water well to supply domestic water to each residence. <br /> 3.0 SOURCES AND IMPACT OF NITRATE TO GROUNDWATER <br /> L 3.1 Current Off-Site Sources of Nitrate <br /> LWe recognize that septic systems,agriculture, and dairies in the area may be the most significant J� <br /> sources of nitrate. Septic tank use in the vicinity is discussed in Section 3.4 of the SSS. <br /> LThe water sample was analyzed for nitrate and DBCP. Nitrate was found at 69.0 mg/L-NO3,which <br /> is above the maximum contaminant level (MCL) set by the US EPA of 45 mg/L-NO3. DBCP was <br /> Lnot detected in the water sample. <br /> Though the water sample indicated elevated nitrates,this would not be unusual for a shallow water <br /> L well in San Joaquin County. We would recommend that the well be inspected and consultation with . <br /> EHD be performed to determine whether the well could be repaired We would recommend not <br /> using the well for drinking water. <br /> L3.2 Contribution of Rainfall <br /> An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. The <br /> Lestimate of deep percolation of rain is based on the average monthly precipitation of rain fall and <br /> evapotranspiration for the Lodi area of California. An estimate of potential deep percolation of <br /> rain determines whether the average monthly precipitation exceeds average monthly potential <br /> evapotranspiration. If so, then the difference is potential deep percolation. This method does not <br /> consider runoff. See Plate 9 for the data and calculation. <br /> LAverage potential evapotranspiration was obtained from the California Irrigation Management <br /> Information System (CIMIS). Stockton is located within evapotranspiration zone number 12. The <br /> average rain fall for the Lodi area was obtained from the Western Regional Climate Center <br /> L (www.wrcc.dri.edu), and was found to be 17.57 inches per year for the years 1948 through 2004. <br /> Based on this method, the average deep percolation of rain for the Lodi area is estimated to be 5.76 <br /> Linches. The nitrate concentration of rain fall was estimated to be 1 mg/L-N (Hantzsche and <br /> Finnemore, 1992). <br /> L <br /> 3 '0044 <br /> L <br />