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LOGE 2126 Page 4 shallow ground water zones. Based on work in the Sacramento Valley from the early 1900s, it is estimated that under “natural” conditions, ground water contains nitrate at concentrations no more then about 3 mg/L-N. Nitrate may be increasing in areas with concentrations of 5.5 mg/L-N or more (Hull, 1984). Although nitrate is a naturally-occurring compound necessary for plant growth, it can cause health problems when present at high levels in drinking water. The most common health effect of nitrates in water is methemoglobinemia, or blue baby syndrome, which results in reduced oxygen supply to vital tissues. Pregnant women and certain others can also develop methemoglobinemia. Symptoms include a bluish color of the skin, as well as headache, dizziness, weakness, and difficulty breathing. Ingestion of high levels of nitrates over time can also lead to gastric problems. DBCP is a nematocide and soil fumigant for vegetables and grapes. It is known to cause male reproductive effects and is classified as a probable human carcinogen. Most domestic use of DBCP was discontinued in 1977 through 1979. The US EPA set the MCL at 0.2 parts per billion (ppb, equivalent to µg/L) because it believes that given present technology and resources, this is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water. The Maximum Contaminant Level Goal (MCLG) for DBCP is zero. On-Site Wells No wells are located on the Site. Mr. Cuellar has indicated that the Site is connected to the municipal water supply. No permits were identified for the Site from the San Joaquin County Environmental Health Department septic permit files. Sources of Nitrate to Groundwater Off-Site Sources of Nitrate Many sources can contribute to ground water nitrate contamination, including agricultural activities, dairies and cattle ranches, septic systems, and storm water infiltration. Dairies, orchards that require fertilization in sandy soils, and septic systems have been found to be the most significant sources of nitrate in ground water. The surrounding properties to the north of the Site are residences, while those to the south are commercial. The majority of the surrounding residences are connected to municipal sewer services.