Suffolk County has launched a new probe into groundwater contamination around the former Grumman plant in Calverton, heeding calls from activists who worry the plume is threatening more private drinking wells, officials said.

The new survey, led by the county's Department of Health Services, will focus on properties that use private wells within three miles from contaminated areas, county officials said.

It expands upon previous efforts by the Navy to sample drinking wells within one mile of the property.Suffolk's new study area could include 160 properties that use private wells, which are more susceptible to contamination because they are shallower than public supply wells and may not be tested as routinely.

Firefighting foams, fuels and solvents disposed of and used at the facility may have contaminated water at the 6,000-acre site where the U.S. Navy assembled and tested fighter jets between 1954 and 1996.

The foams contained perfluoroalkyl and polyfluoroalkyl chemicals known as PFAS, often referred to as ‘forever’ chemicals because they are slow to break down. They have been linked to health concerns including developmental delays, decreased fertility, hormonal deficiencies and cancers, according to the Environmental Protection Agency.

The U.S. Navy is handling cleanup of the contamination at the site but has not taken responsibility for groundwater pollution outside of its boundaries.

Suffolk County Executive Edward P. Romaine said in an interview he ordered the testing to “make sure that we have a complete picture environmentally of what’s going on."

"The impact is being felt on the Peconic River today,” the county executive added,referring to astate warning against eating fish caught from parts of Peconic Lake and the Peconic River due to high levels of PFAS found in samples. The advisory specifically warns against eating yellow perch and largemouth bass caught in those areas and recommends limiting consumption of other species.

Adrienne Esposito, executive director of Citizens Campaign for the Environment and a member of an advisory board overseeing the Navy’s cleanup of the site, has called for more testing.

Data can help map out the extent of contamination as it spreads, Esposito said.

“We need to know the extent of the contaminated plume, distance, length and depth,” she said. “So we know how to attack it to clean it up.”

Testing will investigate a range of contaminants including PFAS, volatile organic compounds and 1,4 dioxane, according to the health department. County health officials said the sampling began on June 2.

The county's survey expands on previous well testing conducted by the Navy. Earlier this year, Navy officials announced a new round of testing of private wells within a one mile radius.

Results released by the department show 17 of 30 wells sampled had PFAS detections, but none met contaminant levels to prompt cleanup actions.

The Navy also recently announced an effort to connect with former Grumman employees that may have firsthand knowledge of practices that could have contributed to the contamination.

Meanwhile, Suffolk County is forging ahead with an independent investigation into the plume. Last year the county health department’s Bureau of Groundwater Investigation and Management began installing and sampling test wells near the Grumman property, to focus on four key areas.

One of those areas includes the northern edge of the property near Route 25A and Middle Country Road in Calverton, because of its proximity to public wells owned by the Riverhead Water District.

Frank Mancini, the water district’s superintendent, said the data will help guide preventive action.

“I need to know: Is this the leading edge of a much worse plume heading toward me?” he said in an interview. “Any data is important to me.”

Romaine expects testing to be completed by August and said results will be publicly available.

If contamination is found, he said the Navy should be held accountable.

“I’m going to take a benevolent look and say they didn’t understand what that impact would be 10, or 20, or 30 years down the road,” he said. “But if we find something, I fully expect ... them to get involved in the cleanup, whatever it takes.”