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F NTRODUCTION Mr. Andrew Sephos is proposing to create two, 2.2f acre residential lots and a Designated Remainder in an unincorporated, unsewered area of San Joaquin County. This report presents the results and findings of our Nitrate Loading Study and Soil Suitability Study conducted as a requirement for this project. The project is located directly north of the city limits of Manteca, on the east side of Highway 99, and on the east side of Mitchell Road. The subject property is currently zoned AU-20. It is described by the United States Public Land Survey System as being a portion of Section 28, Township 1 South, Range 7 East, M.D.B.& M. The two proposed Parcels are currently planted in almonds and the Designated Remainder contains the Sephos Residence. The San Joaquin County Environmental Health Department (PHS-EHD) requires Nitrate Loading and Soil Suitability Studies for projects in unsewered areas, or for projects which may potentially impact the underlying groundwater with nitrate. This report complies with the San Joaquin County Development Title, Section 9-1105.2 for a Nitrate Loading Study and Soil Suitability Study. Additionally, this proposed project must comply with the Environmental Health Department Sewage Standards, specifically Section 10 - "Requirements for Waste Disposal for New Land Developments." The purpose of this Study was to 1.) investigate and quantify current nitrate concentrations, 2.) estimate potential future nitrate impact with conventional septic systems from the proposed project versus leaving the subject property in agricultural production, and 3.) discuss mitigation measures. Our Study finds that the u)per, or highest aquifers in proximity to the subject property have been im acte wit elevated levels of nitrate, predictabl from on-site sej)tic�ms,- agricultural in uts and to a much lesser extent, ackground levels. Estimated future nitrate impact is based on contemporary sc ei nti is owledge use to assess factors which are extremely variable and complex within the soil and groundwater environments. The primary concern of nitrate in drinking water is that high concentrations can cause methemoglobinemia in infants and it can also induce abortion or death in cattle. This disease occurs through a series of complex chemical reactions within the hemoglobin in the blood. Only infants and young children are susceptible. Although this disease is extremely rare, nitrate can also potentially cause other health concerns. There have been scientific studies to suggest that nitrate may produce carcinogenic effects in humans. Nitrate concentrations in water can be expressed in two different terms. 1.) as the weight of the nitrate molecule, which is one atom of nitrogen and three atoms of oxygen for an atomic weight of 62 units. Or, 2.) nitrate can be expressed as the amount of the nitrogen atom itself. This one atom of nitrogen(N) in a nitrate molecule contributes 14 atomic weight units to the weight of the nitrate molecule. The ratio of weight of the nitrate molecule (NO3) to the atom (N) is 62114 or approximately 4.5. The U.S.E.P.A. has established the Maximum Contaminant Level (MCL) of nitrate in drinking water at 45 mg/l as nitrate. Due to the ratio described above, the MCL is sometimes reported as 10 mg/l as nitrate-nitrogen. 1 Valley dig Research