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Percolating Recharge Waters One of the most determinant factors in the Hantzsche and Finnemore equation is the rate of recharge from percolating waters, which mix with the downward-percolating effluent generated by on-site septic systems. In the original Hantzsche and Finnemore paper, only "average recharge rate of rainfall" was considered. Based on San Joaquin County Environmental Health Department policy (personal communication, March 18, 2019), the recharge input for the Hantzsche and Finnemore equation should be derived from average monthly precipitation of rainfall and evapotranspiration rates for the area; the data should be obtained from the California Irrigation Management Information System (CIMIS), preferably from stations located within San Joaquin County. Recharge is calculated by first determining whether the average monthly precipitation exceeds average monthly potential evapotranspiration. If so, then the difference is the percolating recharge water into the aquifer. Runoff and stream infiltration drainage are not factored into the calculation. This approach likely under-estimates recharge to the aquifer and, consequently, over-estimates nitrate loading. For the project Site, the local percolation and evapotranspiration rates are presented in Plate 10. The Site is located closest to the CIMIS Station at Ripon (station 249). Data for the Ripon station were available for the past three years; based on the calculation shown, the estimated rate of recharge from percolating waters for the Ripon station is determined to be 3.00 inches. A statistical error of 34 percent is associated with this value. Quality of Rainwater Hantzsche and Finnemore listed 1 mg/L-N as the nitrate concentration of rainwater for their original calculation; in the past, Live Oak has also utilized this value for the nitrate loading calculation. In May 2019, Live Oak collected rainwater during two storm events in Lodi; in March and May 2020, Live Oak collected two additional samples at the same location. Each sample was collected in a clean, dry, stainless steel bowl, then decanted into a plastic container and placed on ice for transport. The samples were analyzed for nitrate by FGL Environmental of Stockton. Nitrate was detected in the May 17, 2019 sample at a concentration of 0.4 mg/L-N, in the May 19, 2019 sample at a concentration of 0.2 mg/L-N, in the March 16, 2020 sample at a concentration of 0.2 mg/L, and in the May 18, 2020 sample at a concentration of 0.4 mg/L. Live Oak then averaged the concentrations of the four samples, for a value of 0.30 mg/L-N to represent the nitrate concentration of rain. The 2020 analytical reports are attached as Appendix 4. LOGE 20-21 Page 7