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01 April 2021 <br /> Project No. 21-6365 Anfmplo,<< o.,,)cdCo,.,Pan <br /> Page 11 of 15 <br /> specifications of the well and a well completion report could not be located on the DWR <br /> online database. However, well pump repair permits were on file at the EHD indicating <br /> the well was likely installed under EHD permit. The well is currently utilized for the potable <br /> water source at the property and will continue to be used to supply the subject property <br /> with a domestic water source. <br /> 9.0. IMPACT OF NITRATE TO GROUNDWATER <br /> Due to the planned residential use of the property and the potential for nitrate leaching <br /> into the groundwater from the proposed septic system, a nitrate loading analysis for the <br /> future use of the septic system 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 residential land, and is near agricultural land, which might provide a nitrate <br /> source. There are 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) Holt Station #248. Holt <br /> Station #248 has been collecting ETo and precipitation data since January 2017. <br /> Deep percolation (average annual rainfall recharge) was estimated utilizing the monthly <br /> ETo and precipitation data collected from Holt Station #248 between 2017 and 2020. The <br /> annual rainfall average for the area between 2017 and 2020 was 10.50 inches (CIMIS); <br /> the annual ETo average ranged from 0.08 inches in 2020 to 4.68 inches in 2019. The <br /> estimated deep percolation (R) was determined by calculating the average of the ETo <br /> between 2017 and 2020. The estimated deep percolation (R) is 3.05 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. <br /> The current site usage includes a 1,934-square foot house with two bedrooms. <br /> Residential use includes showering/bathing, clothes washing, cooking, and hand <br />