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• Sources of Nitrate Septic systems and dairies have been found to be the most significant sources of nitrate in ground water. Orchards that require fertilization in sandy soils are also a significant source of nitrate contamination in shallow or sandy aquifers in San Joaquin County. Contribution of Rainfall An estimate of the quantity and quality of rainfall was required for the nitrate loading analysis. The Hantzsche and Finnemore method utilizes the "average recharge rate of rainfall' in calculating potential nitrate impacts to the aquifer. Not all rainfall will percolate into the aquifer; evapotranspiration, the sum of evaporation and plant transpiration, will reduce percolating effluent, especially in summer months. Rainfall recharge (deep percolation of rain) is a significant factor in the nitrate loading estimate; however, data on rainfall recharge rates are not widely available. For the Chico area, Hantzsche and Finnemore present an average rainfall of 22.5 inches per year and an estimated rainfall recharge of 16.8 inches per year; the recharge rate is calculated to be 75 percent of the average rainfall. Because the Chico area is similar geologically to San Joaquin County, for the purpose of this report Live Oak has selected 75 percent of rainfall to represent the estimated rainfall recharge for the project area. Rainfall data for the Lockeford area was obtained from the Western Regional Climate • Center. The Elliott station (040010), the closest active station to the Site, reports the average total annual precipitation from July 1926 through May of 2016 to be 18.27 inches. By assuming 75 percent of this precipitation percolates to the aquifer, the value of 13.70 inches average recharge of rainfall is obtained. The nitrate concentration of rainfall was estimated to be 1 mg/L-N (Hantzsche and Finnemore). Quantity and Quality of Domestic Wastewater The following discussion utilizes average customer numbers from the five phases of the project, as presented in the County project application. A discussion including maximum customer numbers from full build-out (Phase 5) of the project is attached in Appendix 6. Ms. Peterson indicated that the stables will be open seven days per week. Monday through Friday, six employees will be present. Saturday, five employees will be present, and Sunday, four employees will be present. Three of the employees who are present all week live in the houses on the Site; as a result, they are excluded as employees from the calculation below. An estimated eight customers per day are anticipated Monday through Friday, 46 on Saturday, and 14 on Sunday. The value for Saturday includes customers attending horse shows that will be held once of twice per • LOGE 1820 Page 9