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30 June 2022 AdvancedGeo Project No. 22-6900 An Employee-Owned Company Page 11 of 15 the California Irrigation Management Information System (CIMIS) Manteca Station #70. Manteca Station #70 has been collecting ETo and precipitation data since January 2014. CIMIS station #262 in Linden, California has only been collecting data since February 2020 and was not used to obtain average potential ETo. Deep percolation (average annual rainfall recharge) was estimated utilizing the monthly ETo and precipitation data collected from Manteca Station #70 between 2017 and 2021. The annual rainfall average for the area between 2017 and 2021 was 11.18 inches (CIMIS); the annual ETo average ranged from 0.48 inches in 2020 to 4.41 inches in 2017. The estimated deep percolation (R) was determined by calculating the average of the ETo between 2017 and 2021. The estimated deep percolation (R) is 2.99 inches (Appendix E). 9.3. CURRENT ON-SITE SOURCES OF NITRATE Septic systems, rainfall and agriculture are sources of nitrates (fertilizers) present on or around the property. The current site usage includes a 4,000-square foot house with three bedrooms. Residential use includes showering/bathing, clothes washing, cooking, and hand washing. The reasonable or maximum usage of wastewater for the three-bedroom house is 100 gpd for the first bedroom and 50 gpd for each additional bedroom for a total of 200 gpd. The total nitrate-nitrogen (NO3_N) average concentrations in domestic waste ranges between 20 to 85 milligram total nitrogen liter (mg/I-N) with an average of 45 mg/I-N when washing and sanitation is considered. The weighted average calculation for total nitrogen concentrations for onsite residential flow is proposed as the following: • Residential volume 200 gpd. • Home use concentration 45 mg/I-N (EHD standard). • The flow concentration of 9,000 mg/I-N gallon. 9.4. FUTURE ON-SITE SOURCES OF NITRATE The future site usage includes the addition of a modular home with three bedrooms for residential use. Residential use includes showering/bathing, clothes washing, cooking, and hand washing. The reasonable or maximum usage of wastewater for the three- bedroom home is 100 gpd for the first bedroom and 50 gpd for each additional bedroom for a total of 200 gpd.