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• 1900s, it is estimated that under "natural' conditions, ground water contains nitrate at <br /> concentrations no more then about 13.5 mg/L-NO3 (3 mg/L-N). Nitrate may be <br /> increasing in areas with concentrations of 24.75 mg/L-NO3 (5.5 mg/L-N) or more (Hull, <br /> 1984). The US EPA has set the Maximum Contaminant Level (MCL) for nitrate as <br /> nitrogen at 10 mg/L. <br /> Although nitrate is a naturally-occurring compound necessary for plant growth, it can <br /> cause health problems when present at high levels in drinking water. The most <br /> common health effect of nitrates in water is methemoglobinemia, or blue baby <br /> syndrome, which results in reduced oxygen supply to vital tissues. Pregnant women <br /> and certain others can also develop methemoglobinemia. Symptoms include a bluish <br /> color of the skin, as well as headache, dizziness, weakness, and difficulty breathing. <br /> Ingestion of high levels of nitrates over time can also lead to gastric problems. <br /> DBCP is a nematocide and soil fumigant for vegetables and grapes. It is known to <br /> cause male reproductive effects and is classified as a probable human carcinogen. <br /> Most domestic use of DBCP was discontinued in 1977 through 1979. The US EPA set <br /> the MCL at 0.2 parts per billion (ppb, equivalent to µg/L) because it believes that given <br /> present technology and resources, this is the lowest level to which water systems can <br /> reasonably be required to remove this contaminant should it occur in drinking water. <br /> The Maximum Contaminant Level Goal (MCLG) for DBCP is zero. <br /> • The laboratory analytical results are attached as Appendix 5 of this report. <br /> Soil Profile and Geologic Information <br /> The Site is mapped on the Geologic Map of California: San Jose sheet (Rogers, 1966). <br /> It is depicted within a map unit of the Modesto formation (Plate 8). <br /> The surface and near surface soils located at the Site are reported by the Web Soil <br /> Survey (USDA, 2017) to be composed of Galt clay, Jacktone clay, and Stockton clay <br /> (Plate 9). The table below presents some selected properties of these soils: <br /> • <br /> LOGE 1702 Page 5 <br />