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I <br /> 1. <br /> V March 22, 2005 <br /> NOA Project Number: E040132A <br /> 2.3 Current and Future On-Site Ground Water Uses <br /> A description of the existing wells on the Site is included in Section 4.2 of the SSS. Ground water is <br /> currently used for residential purposes. Ground water may be developed and used on the second <br /> parcel in the future. <br /> 3.0 SOURCES AND IMPACT OF NITRATE TO GROUND WATER <br /> 3.1 Current Off-Site Sources of Nitrate <br /> Septic systems, agriculture, and dairies in the area may be the most significant sources of nitrate. <br /> Septic tank use in the vicinity is discussed in Section 3.4 was found to be moderate. The ground <br /> L water sample, discussed in Sections 4.4 through 4.7 of the SSS,was found to have a nitrate <br /> concentration of 53.4 mg/L-NO,. This concentration indicates that the ground water aquifer is <br /> V possibly experiencing nitrate leaching from various sources in the area over the long term. <br /> 3.2 Contribution of Rainfall <br /> An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. The <br /> estimate of deep percolation of rain is based on the average monthly precipitation of rain fall and <br /> evapotranspiration for Stockton, California. The estimate first determines whether the average <br /> monthly precipitation exceeds average monthly potential evapotranspiration. If so, then the <br /> difference is potential deep percolation. This method does not consider runoff. See Plate 9 for the <br /> data and calculation. <br /> Average potential evapotranspiration and average rainfall data was obtained from the California <br /> Irrigation Management Information System (CIMIS).The data from January 2004 to December <br /> " 2004 was used for the calculation. <br /> L Based on this method, the average deep percolation of rain for the Manteca area is estimated to be <br /> 5.84 inches. The nitrate concentration of rain fall was estimated to be 1 mg/L-N (Hantzsche and <br /> Finnemore, 1992). <br /> r' 3.3 Current On-Site Sources of Nitrate <br /> l Current on-site sources of nitrate include the current septic system for the residence. <br /> L3.4 Future On-Site Sources of Nitrate <br /> L3.4.1 Quantity and Quality ofDomestrc Wastewater From Proposed Project <br /> LThe following discussion is for determining the long-term waste water flow generated from the <br /> 4 <br /> L <br /> L <br />