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LOGE 2126 Page 3 The longer the effluent remains near the surface, the more biologic treatment may occur. In a situation where permeable soils exist to the depth of the aquifer, it is possible that any remaining surface contaminants may be transported to the first saturated zone of the aquifer. Groundwater Analysis 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 the fall of 2017 and spring of 2018 were the most recent available from this source (Plates 6 and 7). According to an analysis of these maps, the ground-water elevation is approximately five feet above mean sea level. The ground- water flow is to the north or northwest at a rate of approximately three to five feet per mile, depending on the season. Given that the ground elevation of the Site is approximately 20 feet above sea level, based on the County ground water maps the depth to ground water beneath the Site is estimated to be approximately 15 feet. Potential Ground Water Contamination Issues The Nitrate Loading 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 and cattle ranches, 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 nitrate map, two wells within a one-mile radius of the subject Site have been tested for nitrate; it was detected in one well at a concentration between 0.1 and 5.0 mg/L-N, and in the other well at a concentration between 5.1 and 10.0 mg/L. Two wells within a one-mile radius of the Site were tested for DBCP; no DBCP was detected in either well. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate is 10 mg/L-N; the MCL for DBCP is 0.2 µg/L. Nitrate is commonly detected in shallow ground water aquifers of the Central Valley. Application of fertilizers, livestock waste, and untreated septic tank waste can all contribute to nitrate in ground water. Nitrate is mobile and tends to accumulate in