Orange County North Basin Superfund Site

The Orange County North Basin Superfund Site focuses on a six-and-a-half-square-mile portion of the groundwater aquifer located under Fullerton, Anaheim and Placentia. 

Manufacturing industries operating primarily in the 1950s, 60s and 70s left a legacy of industrial pollutants at their former factories. The pollutants, mostly volatile organic compounds (VOCs) including solvents and degreasers, have migrated through the soils and are now leaching into the underlying groundwater. These VOCs have impacted nearby water supply wells causing five of them to be taken out of service.  

With oversight from the United States Environmental Protection Agency (EPA) , OCWD is conducting a Remedial Investigation/Feasibility Study (RI/FS) to further characterize areas with elevated contaminant concentrations (the RI), and develop and evaluate alternatives (the FS) for an Interim Remedy that remediate parts of the plume that pose a more imminent threat to local groundwater supplies. 

OCWD has completed the RI for the Interim Remedy, which included installing 23 monitoring wells at 13 locations. These wells complement the extensive network of 80 existing monitoring wells OCWD previously installed to characterize groundwater contamination in the North Basin area. OCWD also completed the sampling of approximately 90 new and existing wells. A Draft Interim RI Report is being reviewed by EPA and should be finalized by early 2021. The District is currently working on the Interim FS, which is expected to be completed in 2021.  EPA will propose a preferred alternative, will seek public review and comments on that proposal, and then select the Interim Remedy.

On September 3, 2020, the Orange County North Basin Superfund Site (formerly North Basin Site) was listed by the EPA as a National Priorities List (NPL or Superfund) site. The goal of the Superfund listing is to get contamination contained and cleaned up, and to compel parties responsible for the contamination to implement and pay for the cleanup.

EPA is starting a comprehensive RI/FS to address parts of the plume that will not be remediated with the Interim Remedy. In early 2021, EPA plans to install six monitoring wells at two locations. The comprehensive RI will likely require many more monitoring wells. EPA will work with the potentially responsible parties to continue to conduct the comprehensive RI/FS, and to implement additional remediation to supplement the Interim Remedy if deemed necessary.


North basin plume map

Please click on the graphic below to view the plume map full screen.

North Basin Remedial Investigation

OCWD updates and agenda items

For all items pertaining to the project, please search our meetings and agendas page.

OCWD fact sheets & additional information

U.S. Environmental Protection Agency (EPA)