San Gabriel Valley (Area 3) is a 19-square-mile Superfund site in Los Angeles County, covering the cities of Alhambra, Rosemead, San Gabriel, San Marino, South Pasadena, and Temple City. It was added to the National Priorities List in May 1984. Land use across the area is mainly commercial and residential, with limited light industry and open space. The site is one of four contaminated groundwater areas within the broader 170-square-mile San Gabriel Valley that EPA listed that year.
The main contamination concern is volatile organic compounds (VOCs) and industrial solvents in groundwater. More than 100 facilities contaminated over 30 square miles of groundwater, and about 400 facilities in the region have soil contamination. The contaminated groundwater spans isolated areas across the site's 19 square miles.
Several cleanup actions are underway. Since 2008, the City of Alhambra has operated a water treatment plant to remove VOCs and industrial solvents from the drinking water supply. Water utilities in the area currently provide water that meets all state and federal drinking water standards. The State of California has investigated more than 20 current and former industrial facilities to identify contamination sources and oversees cleanup of soil and soil gas contamination at several former industrial sites. EPA performed a removal action at the site in January 2020 and is working on a supplemental Remedial Investigation and Feasibility Study to identify and evaluate groundwater cleanup options. A combined remedial investigation and feasibility study for the Alhambra operable unit began in July 1999 and is estimated to be completed between September and November 2028.
Human exposure across the site is currently under control, with no unacceptable human exposure pathways identified. However, the migration of contaminated groundwater is not stabilized. Physical construction of the cleanup is not yet complete, and the site has not been deleted from the National Priorities List or certified as ready for anticipated use.
Community members can review site documents at three local libraries: Alhambra Public Library, West Covina Public Library, and Rosemead Library. Records are also available at the EPA Region 9 Regional Records Center in San Francisco. For questions, the public can contact the EPA Community Involvement Coordinator or the Remedial Project Manager.
