EPA continues its investigation to identify sources of the contamination.  Potentially responsible parties have yet to be named by the EPA.

San Gabriel Valley (Area 4) is a ground water plume that runs along the axis of the San Jose Creek in the San Gabriel ground water basin in La Puenta, Los Angeles County, California. The plume is about 1 mile long and 1 mile wide.

Ground water is contaminated with trichloroethylene (TCE) and perchloroethylene (PCE), according to analyses by State agencies and local water companies. Many public wells in the area exceed the EPA Suggested No Adverse Response Levels (SNARL) for TCE and PCE. Approximately 100,000 people are affected