The Newmark Ground Water Contamination site covers an 8-square-mile area of polluted groundwater in San Bernardino, California. EPA added it to the National Priorities List (NPL) in 1989 after the state identified two large plumes of contaminated groundwater. The Newmark plume stretches 5 miles and the Muscoy plume stretches 4 miles, both reaching several hundred feet deep. Land above the plumes includes residential, commercial, and light industrial areas, and city development has continued without disruption.
EPA identified 14 contaminants of concern, all found in groundwater. The most common are tetrachloroethene and trichloroethene, which are industrial solvents also known as volatile organic compounds (VOCs). Other contaminants include 1,1-dichloroethane, cis-1,2-dichloroethene, trans-1,2-dichloroethene, dichlorodifluoromethane, and trichlorofluoromethane. Investigators could not trace the contamination to a single source.
The site is divided into three operable units (OUs), each targeting a different area or problem. The Newmark OU has been treated by pump-and-treat systems using activated carbon adsorption since 1998. Long-term response action for that unit concluded in February 2024, and operation and maintenance is expected to wrap up between November 2026 and January 2027. The Muscoy OU completed active remedial work in 2007 and is currently in operation and maintenance, with its treatment facility running since 2005. The Source OU is the newest focus. EPA selected a remedy for it in May 2024 that combines sampling, monitored natural attenuation, and institutional controls rather than active treatment equipment. Remedial design for the Source OU is estimated to run from November 2026 through January 2028.
Human exposure is currently under control, with no unacceptable exposure pathways identified. Groundwater migration is also stabilized, with no unacceptable discharge to surface water. EPA will continue monitoring to confirm contamination stays within the known area. Physical construction is not yet complete across the whole site. A groundwater management agreement among local water suppliers uses institutional controls to keep contaminated water from spreading. EPA conducts five-year reviews to confirm the cleanup continues to protect public health. The most recent review was completed in September 2023, and the next is estimated between September and November 2028. As of December 2024, 132 businesses operating at the site employed 2,702 people and generated about $711 million in annual sales.
Community members with questions can contact the EPA staff assigned to the site. Site records are available at the EPA Region 9 Superfund Records Center in San Francisco or at the John M. Pfau Library at California State University, San Bernardino.
