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18 September 2020 AdvancedGeo <br /> Project No. 20-6116 An Employee-Owned Company <br /> Page 11 of 15 n,'V <br /> 8.3. CURRENT AND FUTURE USE OF GROUNDWATER AT THE SITE <br /> Water supply well DW-1 conforms to DWR and EHD standards and is used, and will <br /> continue to be used, to supply the subject property with a domestic water source. <br /> 9.0. IMPACT OF NITRATE TO GROUNDWATER <br /> Due to the use of the property and the potential for nitrate leaching into the groundwater, <br /> a nitrate loading analysis is required by the EHD. <br /> 9.1. CURRENT OFF-SITE SOURCES OF NITRATE <br /> Septic systems and agriculture are sources of nitrates in the area of the site. The property <br /> is bordered by agricultural land, which might provide a nitrate source. There are also <br /> several residences within 1,000 feet of the site. <br /> 9.2. IMPACT OF RAINFALL CONTRIBUTION TO NITRATE LOAD <br /> The rainfall of the area has been estimated for the nitrate loading analysis. Deep <br /> percolation is estimated by calculating the average monthly rainfall and <br /> evapotranspiration of the site area. If average monthly rainfall exceeds average monthly <br /> potential for evapotranspiration (ETo) there is a potential for deep percolation without <br /> consideration for runoff. Average potential ETo was estimated from data obtained from <br /> the California Irrigation Management Information System (CIMIS) Ripon Station #249. <br /> Deep percolation (average annual rainfall recharge) was estimated utilizing the monthly <br /> ETo and precipitation data collected from Ripon Station #249 between 2017 and 2019. <br /> The annual rainfall average for the area between 2017 and 2019 was 12.32 inches <br /> (CIMIS); the annual ETo averages were 4.13 inches in 2017, 2.11 inches in 2018, and <br /> 2.77 inches in 2019. The estimated deep percolation (R) was determined by calculating <br /> the average of the ETo between 2017 and 2019. The estimated deep percolation (R) is <br /> 3.00 inches (Appendix E). <br /> 9.3. CURRENT ON-SITE SOURCES OF NITRATE <br /> Septic systems, rainfall and agriculture are sources of nitrates (fertilizers) present on or <br /> around the property. There are currently no septic systems located at the subject <br /> property. <br />