Calverton plume at ex-Grumman site is more extensive than Navy acknowledges, Suffolk testing shows

A far more extensive plume of industrial chemicals is spreading beyond the former Grumman site in Calverton than the U.S. Navy has acknowledged, according to years of independent water testing by the Suffolk County Health Department.

The findings, presented by the county at a forum in Manorville on Tuesday night, show the hazardous and in some cases carcinogenic chemicals are migrating directly toward the Peconic River, putting the entire estuary at risk, according to a Suffolk hydrogeologist. 

Residents, environmental advocates and local officials have grown frustrated by what they say is the Navy moving too slowly to confront the full extent of the pollution. The Navy is "dragging their feet," said Adrienne Esposito, executive director of Citizens Campaign for the Environment, in an interview with Newsday before the forum.

Navy officials did not participate in Tuesday’s forum, though a Navy representative was in the audience taking notes. A Navy spokesman reached by email after the meeting pushed back against the county's findings. 

The 6,000-acre former Grumman site was used to build and test fighter jets from 1954 to 1996.

"We're pretty far ahead of the Navy with respect to the off-site data," Andrew Rapiejko, a hydrogeologist with the Suffolk County Health Department, said Tuesday as he presented detailed data and maps tracing the plume’s path.

County: High levels of PFAS found

The county’s analysis showed high concentrations of PFAS, a class of forever chemicals linked to cancers, infertility and other health risks, and 1,4 dioxane, a likely carcinogen, in the plume, which discharges into the Peconic.

The Navy turned down a request to review Rapiejko's report in a February meeting it sanctioned in Riverhead, according to members of a citizen cleanup advisory board appointed by the Navy. The board is again calling on the Navy to review the report and accelerate cleanup to stop the plume from entering the river.

Tuesday's meeting struck an urgent tone among nearly 100 residents who filled a conference room at the Manorville Fire Department.

Kelly McClinchy, a Manorville resident who led a grassroots effort to get public water main extensions, said the fight for clean water was "just the beginning."

About 120 properties have been connected to public water in nearby residential areas using more than $22 million in federal, state and local funding.

"We think we’ve gone over this hurdle, but we’re not there yet. What caused us to need [clean water] ... hasn’t been addressed sufficiently," McClinchy said.

Swan Pond pollution

Late last month, Suffolk County banned fishing in Swan Pond, south of the Grumman site, after Navy tests revealed high levels of PFOS in freshwater fish in the waterway, Newsday reported. PFOS and another type of chemical found in the pond, PFOA, are part of the larger PFAS group, according to the U.S. Environmental Protection Agency.

Esposito said the Navy had data about fish in Swan Pond for more than a year before sharing it with Suffolk County.

"Their actions have been unconscionable and basically criminal. They let people eat toxic fish," Esposito said.

Navy spokesman David Todd pushed back on the county’s findings Tuesday night, saying it could not verify if their data meets federal guidelines.

"Sampling and analysis conducted by the County is not subject to the same rigorous data quality standards," Todd wrote in an email to Newsday.

Todd said the agency is investigating PFAS contamination at the site and "has begun efforts to stop PFAS migration and reduce surface water concentration" near Swan Pond. More updates will be provided at a June 9 Restoration Advisory Board meeting, he said.

According to Rapiejko, two "high concentration" 1,4 dioxane plumes were detected near the wetlands, with one sample as high as 14.9 parts per billion. The state drinking water standard is 1 part per billion.

The highest PFAS concentration detected was PFNA, at 7,580 parts per trillion, according to Rapiejko. Tests showed 580 ppt of PFOA and 63 ppt of PFOS, for which the state has set drinking water standards of 10 ppt. 

Samples of surface water from the Peconic River showed one site rose from 4 ppt in 2024 to 100 ppt in 2026, which Rapiejko said is a concerning increase.

Suffolk study launched

The plume appears to follow a similar path as an earlier plume of volatile organic compounds, which the Navy addressed by installing treatment wells more than a decade ago.

"A properly designed remediation system in the right place doing the right thing, you really can make an impact and help the environment and prevent additional contamination," Rapiejko said.

Last year, Suffolk also launched its own study of private drinking wells in the area after the Navy said it did not detect levels above their standard of 12 ppt at residential homes. Of 37 properties sampled by the county last year, 11 tested positive for PFAS. Three of the homes were above state drinking water limits, according to the data.

Critics say the Navy’s process to address emerging contaminants in Calverton has been vexingly slow.

"The Navy for 30 years left the place and did not clean it up," County Executive Edward P. Romaine said Tuesday. "We're going to let all the facts out ... because they left a gift that will keep on giving in the wrong way for many years."

Esposito said the Navy is "dragging their feet" in Calverton, but not in Bethpage. At the ex-Grumman facility there, the Navy is spending $46 million on a new water treatment plant to contain a plume at a former Grumman facility, Newsday reported earlier this month.

"Why isn’t our community valued?" Esposito said. "We deserve clean water."

Toward the back of the room, a group of fishermen listened to the presentation and said they were concerned about losing access to Swan Pond, a popular and secluded spot for the sport.

Mark Fehner, 37, of Manorville, said that could have ripple effects on other water bodies and also fears future impacts to the rest of the Peconic River and bays.

"You're going to see packed-out parking lots at the other places, much more fishing pressure and fish taking," Fehner told Newsday. "It's going to be detrimental."