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Ground Water Information Depth and Gradient Live Oak reviewed ground-water elevation information available from the San Joaquin County Flood Control and Water Conservation District to determine the ground-water levels near the Site. Data from spring and fall of 2016 were the most recent available from this source. According to an analysis of these maps (Plates 4 and 5), ground- water elevation is approximately 60 to 67 feet below mean sea level. Ground water appears to flow to the north at a rate of 4 to 8 feet per mile. Given that the ground elevation of the Site is approximately 60 feet above mean sea level, the depth to water below the Site is estimated to be approximately 120 to 127 feet. San Joaquin County experienced its highest recent ground-water levels in 1983 and 1999. Maps of ground-water levels were reviewed for this study (San Joaquin County Flood Control and Water Conservation District, 1983 and 1999); depth to ground water was approximately 92 to 97 feet for these years (Plates 6 and 7). Potential Ground Water Contamination Issues The Soil Suitability Study is not intended to be an investigation into ground-water contamination sources, and no such investigation was conducted. Many sources can contribute to ground-water contamination, including leaking underground storage tanks, agricultural activities, dairies, septic systems, and storm water infiltration. Agricultural activities and the use of septic systems in the area are known ground-water contamination sources with the potential to impact the Site. Two common ground-water contaminants in San Joaquin County are nitrate and dibromochloropropane (DBCP). Live Oak reviewed the San Joaquin County Environmental Health Department's maps of Nitrate— Land Use Data and DBCP— Land Use Data dated February 20, 2019 (Plates 8 and 9). According to the maps, no wells within a one-mile radius of the subject Site have been tested for either constituent. Farther from the Site, nitrate concentrations range from non-detect to over 10 mg/L-N, with most concentrations in the 0.1 to 5.0 mg/L-N range. DBCP detections are uncommon in the area. On-Site Wells A domestic well is located on the Site. One well permit was identified for the Site from among the files of the San Joaquin County Environmental Health Department. The permit, dated September 2014, was for pump replacement at the domestic well; it has been included in Appendix 4. LOGE 20-22 Page 3