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within a half -mile radius of the subject Site have been tested for nitrate. Nitrate was detected in one of these wells at a concentration between 0.1 and 5.0 mg/L-N; no nitrate was detected in the other well. According to the DBCP map (Plate 8), two wells within a half -mile radius of the Site have been tested for DBCP; no DBCP was detected in either well. It should be noted that, further from the Site, many wells in the east Lodi area do exhibit DBCP over the MCL. The Maximum Contaminant Level (MCL) set by the US EPA for nitrate is 10 mg/L-N; the MCL for DBCP is 0.2 µg/L. Nitrate is commonly detected in shallow ground water aquifers of the Central Valley. Application of fertilizers, livestock waste, and untreated septic tank waste can all contribute to nitrate in ground water. Nitrate is mobile and tends to accumulate in 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). The US EPA has set the Maximum Contaminant Level (MCL) for nitrate at 10 mg/L-N. 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 One well is currently located on the Site; it appears to be the old agricultural well from the former house, discussed above. The well is not currently connected to a power supply. No well permits were identified for the Site from among the files of the San Joaquin County Environmental Health Department. The housing abatement Complaint Investigation Report discussed above included a sketch indicating both an agricultural well and a domestic well (Appendix 4). LOGE 2221 Page 4