State DEC commissioner Amanda Lefton met with business leaders Thursday in Melville.

She spoke about the plume linked to the Navy and Norththrop in Bethpage.

The plume is one of the largest in the country spreading as far south as the Southern State Parkway.

It’s taken decades to try to contain it and clean it up.

"Actually, over 80% of the plume has been cleaned up and the entire plume has been contained. So we continue to make great progress with the navy to make sure there are wells installed for that containment, we'll have some milestones actually coming up a little bit later this year,” said New York State DEC Commissioner Amanda Lefton.

Lefton says work is also continuing on two off-shore wind farms.

The Trump administration tried to stop the projects because of what it calls national security concerns, but courts have said work can resume.