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March 6,2001 4 Job Number:LGO0 426 Page 4 1998 was toward the east to southeast with a gradient of about 5.3 feet per mile(Plate 4). For Spring 1999, the flow direction was southeast with a gradient of about 6.5 feet per mile(Plate 5). A request was submitted to the California Department of Water Resources (DWR)to obtain logs or information for the existing water well located just west of the home. Ms. Ann Roth (DWR) was not able to locate any records for the subject well (see letter in appendix). A water sample was obtained from the well on January 4, 2001 and sent to FGL Environmental Laboratory for testing. The samples were tested for the presence of �- dibromochloropropane(DBCP) and Nitrate(NO3)per County requirements. The test results indicated that DBCP was non-detectable (ND) and nitrate as NO3 was found at 1.04 mg/l 22.8 mg/1-N). The result of the nitrate test indicates the ground water is above the maximum '- contaminate level set by the United States Environmental Protection Agency of 45 mg/l-NO3 for nitrate(or 10 mg/l as Nitrate N). The presence of nitrates and DBCP are not uncommon in shallow ground-water aquifers in San.Joaquin County and other parts of the Central Valley. Nitrate in ground water occurs as a result of the application of fertilizers, livestock waste, and untreated septic tank waste. Nitrate is mobile and often accumulates in the shallow ground-water zones. In the early 1900's,natural levels of nitrate in ground water were measured in forty-three(43)wells throughout the Sacramento Valley by Bryan.' It was thought that ground water at that time was close to "natural" conditions. Based on the work by Bryan, it is estimated that under"natural" conditions, ground water concentration containing nitrate is no more then about 13.5 NO3 (3 �. mg/L-N). Areas having 24.75 mg/L NO3 (5.5 mg/L-N) or more are those in which nitrate concentrations may be increasing.3 DBCP was not detected in the water sample. DBCP is a nematocide and soil fumigant for vegetables, and grapes. It is thought to cause health problems consisting of kidney damage, liver damage, and cancer. The use of DBCP was discontinued in 1979. The Environmental Protection Agency(EPA) set the maximum contaminate limit(MCL) at 0.2 parts per billion (ppb) because the EPA believes that given present technology and resources, this is the lowest 'Bryan,K., 1923,Geology and ground-water resources of Sacramento Valley of California:U.S. i Geological Survey Water-Supply Paper 495,285p. 3 Hull,L.C., 1984,Geochemistry of Ground Water in the Sacramento Valley,California:U.S.Geological Survey Professional Paper 1401-B. x o � �Ssoc� r i