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LOGE 1907: Bavaro SS/NLS Addendum 3 Page 4 March 15, 2019 method, it is our understanding that the source for both the precipitation and evapotranspiration data will be the California Irrigation Management Information System (CIMIS); data from the most recent five years will be utilized. Because a final determination on the recommended method has not yet been made, for this project a straight subtraction of monthly evapotranspiration from precipitation per year will be used to derive a recharge value. For the project Site, the local percolation and evapotranspiration rates are presented in Plate 1. The closest station to the Site that is also within San Joaquin County, Manteca (station 70), has been selected; the past five years of annual data were utilized. Based on the calculation shown (Plate 1), the estimated rate of recharge from percolating waters for the Escalon, California area would be 3.64 inches per year by this method. • Reduced Rainfall: For this method, rainfall levels from the closest rain station are multiplied by a percentage based on a reasonable assumption from the literature. Because the Hantzsche and Finnemore model utilized a value of approximately 75 percent rainfall as the rate of recharge from percolating waters in the Chico area (which is more geologically similar to San Joaquin County than the other two locations discussed in the paper), that value is applied to local rainfall in the project area. The San Joaquin County Environmental Health Department consistently approved this method from January 2017 through January 2019. As discussed in the 100 percent rainfall section (above), the average of the three closest WRCC rain stations yields an annual rainfall value of 12.46 inches (Table 1). Assuming 75 percent of this precipitation percolates to the aquifer (as Hantzsche and Finnemore did in Chico), the rate of recharge from percolating waters is calculated to be an average of 9.3 inches per year. • Regional Recharge from Percolating Waters: In 2018, the Eastern San Joaquin Groundwater Authority (ESJGA) commissioned a comprehensive ground-water model covering parts of San Joaquin County, northern Stanislaus County, and southern Sacramento County. In the model, percolating recharge waters throughout the Eastern San Joaquin subbasin (portion of the model area) were evaluated; a value of 650,000 acre-feet was used for ground-water recharge throughout the subbasin. This value was derived after numerous model calibration runs. By dividing 650,000 acre-feet by the total acreage of the subbasin (772,377 acres), and converting to inches, a regional rate of recharge from percolating waters throughout the subbasin was found to be 10.1 inches per year. This value should be viewed as an average for the subbasin area. Calculated Rates of Recharge from Percolating Waters for Project Site The following table summarizes the values for rate of recharge from percolating waters obtained from the methods discussed above for the project Site: