Extremely small traces of a chemical used in pesticides for orchard crops as well as in industrial solvents has been detected in a Manteca municipal water well.

There is no immediate health risk although the well located in the Manteca Industrial Park along Vanderbilt Circle near Main Street and the 120 Bypass must be monitored under state and federal laws.

The chemical 1,2,3-Trichlorpropane was detected during testing on July 23. The well has 38  parts per trillion of 1,2,3-TCP.  The State of California mandatory reportable threshold is 5 parts per trillion while the federal Environmental and Protection Agency’s reporting threshold is 30 parts per trillion.

 To put that in  perspective, 38 parts per trillion is the euquiaveklnt of 38 drops of water diluted into 20-Olympic-sized swimming pools. Environmental laws do not require any action  to be taken unless the 1,2,3-TCP contamination reaches 500 parts per trillion or 13 times higher than what was detected July 23.

Public Works Director Mark Houghton told the Manteca City Council that 1,2-3-TCP has never been detected at reportable levels before at the well. He theorized the city’s shift to reliance on ground water exclusively for more than a week while the surface water main from the treatment plant was being relocated due to the Lathrop Road interchange construction on  Highway 99 may have caused the jump in 1,2,3-TCP.

Water drawn from the well, just like other wells in the city, is mixed with surface water as part of a larger looped and diluted water system.

The notification levels are advisory only and are not connected with enforceable standards. State law requires that the governing body that oversees the water operation where 1,2,3-TCP is detected  — in this case the Manteca City Council — must be notified within 30 days of the chemical’s detection. Such notification is mandatory to make sure water users are made aware of any non-regulated chemicals that may be in drinking water. The city routinely provides similar disclosures each month in a sheet mailed with utility bills.

All potable municipal water in Manteca  has been cleared as safe for human consumption

TCP is recognized by California as a human carcinogen.

Water Treatment Operations Supervisor George Montross in a report to the council noted that, “for the purpose of full disclosure, some people who use water containing 1,2,3-TCP in excess of the notification level over many years have an increased risk of getting cancer, based on studies in lab animals.”