Smithtown Ground Water Contamination

Overview

The Smithtown Ground Water Contamination site sits in Smithtown, Suffolk County, New York, covering the communities of Nissequogue, Head of the Harbor, and St. James on Long Island. EPA placed it on the National Priorities List in January 1999 after finding volatile organic compounds (VOCs, a broad class of chemical vapors) in private wells across the area. The site has since completed cleanup and was deleted from the list in August 2023, meaning it no longer requires further action under the Superfund program.

The main contaminant driving cleanup was perchloroethylene (PCE), a dry-cleaning solvent. Investigators identified 14 contaminants of concern total in groundwater, including other solvents such as trichloroethene and chloroform, metals including arsenic, chromium, and manganese, and other substances like MTBE (a fuel additive) and aluminum. A remedial investigation could not pinpoint a single source. Instead, it found sporadic, isolated pockets of contamination rather than one continuous underground plume.

EPA began responding in April 1998, before the site was formally listed, by distributing bottled water to affected residents. Cleanup then moved to connecting homes to public water mains where those mains existed, and installing or upgrading household carbon filtration systems where they did not. Construction of the long-term remedy started in August 2005, with the last residential connections to public water completed by September 2006. All construction work wrapped up in September 2009. The 2004 Record of Decision, the formal document selecting the cleanup approach, called for alternate water supplies, long-term groundwater and surface water monitoring, and restrictions on groundwater use.

Long-term monitoring showed the groundwater aquifer recovered to meet state and federal drinking water standards. EPA completed three five-year reviews, the most recent in November 2020, each confirming the cleanup protects public health and the environment. After that third review, EPA determined no further five-year reviews are needed. The site reached Sitewide Ready for Anticipated Use status in September 2018, confirming that all cleanup goals for current and expected future land uses are met and no unacceptable risks remain. Human exposure and groundwater migration are both considered under control. The EPA Superfund Redevelopment Program is also working with the community to support the site's return to productive use.

Community members with questions can contact EPA's Community Involvement Coordinator or Remedial Project Manager. Site documents are available at the EPA Superfund Records Center at 290 Broadway, 18th floor, New York City, and at the Smithtown Library at 1 North Country Road in Smithtown.