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4.2 Description/discussion of any existing and/or potential groundwater contamination issues in the general location of the site: Description of existing or potential groundwater contamination issues in the general location of the site are referred to in Section 4.2 of the Soil Suitability Report prepared by Dillon&Murphy that is attached in the Appendix. 4.3 Description of the current use of groundwater at the site and of the future expected use of groundwater as related to the proposed development project: Based on the most recent results from San Joaquin County's "Flood Control and Water Conservation District" report on groundwater from spring 2018, the estimated depth to groundwater was determined to be 150 to 160 feet below the surface. This was verified with the California Department of Water Resource's Water Data Library. The results of the historic depth to ground water show that the relative depth has slightly dropped in recent years. The proposed improvements will not have a negative effect on the current depth to ground water as residential use will not change. See appendix for the site's depth groundwater tables and diagrams. 5.0 SOURCES AND CALCULATED IMPACT OF NITRATE TO GROUNDWATER 5.1 Description of all current off-site sources of nitrate to soil and groundwater in the general up gradient area and the contribution of nitrate load from these sources to the project site: Current off-site source of nitrate to soil and groundwater in the general up gradient area and the contribution of nitrate loads are agriculture and neighboring sites with septic systems with minimal to no current impact to the site. 5.2 Description of impact of rainfall contribution of nitrate load to the project site: The impact of rainfall contribution on the project site was completed to determine the nitrate load. The average monthly precipitation and evotranspiration are required to calculate the site nitrate load. These two values are used to estimate the deep percolation. The deep percolation is estimated by analyzing the difference between the monthly average precipitation and the evotranspiration when the monthly precipitation exceeds the monthly evaporation. These calculations are attached in the Appendix. The data for the potential evotranspiration water was obtained from the California Irrigation Management Information System (CIMIS). The project is located within an area designated as Zone 12. Based on the values for this area along with the average monthly precipitation values obtained from the Western regional Climate Center (Station 70) for Manteca were used as an estimate of the deep percolation of rain for the project was determined. The precipitation was determined from the City of Stockton Fire Station#4. The results for the deep percolation at the site were 3.56 in./year. The nitrate concentration is estimated to be about 1 mg/L-N. (Hantzche and Finnemore, 1992). 5.3 Description of all current on-site sources of nitrate to soil and groundwater and the contribution of nitrate load from these sources to the project site: The only source of nitrates are the existing septic system in use by an existing parcel for residential uses and agriculture use. The existing septic systems were accounted for when determining the approximate nitrate concentration, the site could expect with the proposed development. 4