The state Department of Health Services has ordered new tests on eight to 10 wells in the Pasadena-Arcadia area after the discovery that an East Pasadena Water Co. well is contaminated with an industrial chemical.
The contamination involves 1,1-dichloroethylene (DCE), a chlorinated hydrocarbon used in plastics and paper-coating processes. The compound is classified as a suspected carcinogen because it has caused cancer in laboratory animals, although its effect on humans is unclear, according to state health officials.
East Pasadena Water Co. serves 8,000 residents in the unincorporated area between Pasadena and Arcadia and in small portions of Arcadia and Temple City. Robert Mraz, water company manager, said DCE was found in a well that had been out of service since December. He said the well will remain shut down until it can meet state health standards. Mraz said the company has two other wells that can pump enough water to meet the needs of customers.
Gary Yamamoto, state senior sanitary engineer, said the source of the contamination “is a complete mystery.” There are no factories near the well, at 3725 Mountain View Ave., Pasadena, he said, and DCE has never before been found in wells in the Raymond Basin.
Other Wells Contaminated
Sixty wells in the main San Gabriel Basin, which stretches from Monterey Park to La Verne, are contaminated with a variety of chlorinated hydrocarbons, including DCE. The neighboring Raymond Basin lies north of Huntington Drive from Pasadena’s Arroyo Seco to Arcadia.
Yamamoto said it will take one or two weeks to conduct tests to find out if the contamination involves more than one well in the Raymond Basin. Mraz said his company’s other two wells have been checked and are not contaminated. The contaminated well had 4.5 parts per billion of DCE.
Yamamoto said the state action level for DCE is extremely low--0.2 parts per billion, which is near the detectable limit. The action level is the point at which the state advises water companies to either shut down a well or treat or blend the water to reduce contamination.