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Soil Suitability I Nitrate Loading Study 1rerracon <br /> Whitlow Property ■ Stockton, CA <br /> November 20, 2019 . Terracon Project No. NA197078 <br /> 2.2 Groundwater Analysis <br /> 2.2.1 Regional Groundwater <br /> A discussion of regional groundwater, including depth to groundwater is included in Section 1.4.1. <br /> No significant seasonal trends were evident from the sources consulted. <br /> 2.2.2 Potential Ground Water Contamination Issues <br /> A discussion of issues related to potential groundwater contamination is included in Section 1.4.2. <br /> 2.2.3 Current and Future On-Site Ground Water Uses <br /> An existing domestic groundwater supply well will provide drinking water for the proposed <br /> development. <br /> 2.3 Sources and Impact of Nitrate to Groundwater <br /> 2.3.1 Current Off-Site Sources of Nitrate <br /> Agriculture land use and septic systems in the area may be the most significant sources of nitrate <br /> in groundwater. Septic tank use in the vicinity is discussed in Section 1.3.5. <br /> 2.3.2 Contribution of Rainfall <br /> An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. <br /> Average precipitation and potential evapotranspiration data was obtained From the California <br /> Irrigation Management Information System (CIMIS) from the Lodi (042) and Lodi West (166) <br /> stations nearest the site. The estimate of deep percolation of rain is based on the average <br /> monthly precipitation of rain fall and evapotranspiration for San Joaquin County, Cafifomia. The <br /> estimate first determines whether the average monthly precipitation exceeds average monthly <br /> potential evapotranspiration. If so, then the difference is potential deep percolation. This method <br /> does not consider runoff, although due to the relatively flat nature of the site, runoff should be <br /> minimal. <br /> Table 9. <br /> Estimate of Deep Percolation of Rain <br /> Location Average Deep Percolation of Rain <br /> Lodi Area 4.49 inches per year <br /> Based on this method, the average deep percolation of rain for San Joaquin County is estimated <br /> to be 4.49 inches/year. <br /> Responsive ■ Resourceful ■ Reliable 15 <br />