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May 17, 2007 <br /> NOA Project Number: E07064A <br /> 2.3 Current and Future On-Site Ground Water Uses 0- <br /> The <br /> use of ground water for drinking water is planned for the proposed development. <br /> i <br /> 3.0 SOURCES AND IMPACT OF NITRATE TO GROUND WATER <br />€ � <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 in 1 <br /> the county. Septic tank use in the vicinity is discussed i Section 3.4 of the SSS. <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 Northern Stockton, California. The estimate first determines whether the <br /> average 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 1 for the �_2 2 <br /> �. data and calculation. �f} .C,[TJ err i-✓/��"T <br /> Average potential evapotranspiration was obtained from the California Irrigation Management <br /> Fj Information System (CIMIS). Stockton is located within evapotranspiration zone number 12. The <br /> average rain fall for the North Stockton area was obtained from the Western Regional Climate <br /> Center (www.wrcc.dri.edu), and was found to be 15.98 inches per month for the years 1965 through <br /> 1977. <br /> Based on this method, the average deep percolation of rain for the North Stockton area is estimated <br /> to be 4.67 inches. The nitrate concentration of rain fall was estimated to be 1 mg/L-N (Hantzsche <br /> and Finnemore, 1992). <br /> Fj3.3 Current On-Site Sources of Nitrate <br /> Current on-site sources of nitrate include any current septic systems on the property. No additional l3 3> <br /> sources of nitrates besides septic effluent,groundwater and rainfall are recognized. <br /> 3.4 Future On-Site Sources of Nitrate <br /> 3.4.1 Quantity and Quality of Domestic [wastewater From Proposed Project <br />� <br /> Fill <br /> The following discussion is for determining the long-term waste water flow generated from the <br /> proposed residences or commercial usage for the nitrate loading analysis and should not be used for <br /> F] septic system design purposes. Typically, use estimates for the sizing of septic systems include a <br /> 4 <br />