Sampling performed by State University at Stony Brook researchers has confirmed blooms of cyanobacteria, or blue-green algae, at Fort Pond in Montauk, Poxabogue Pond in Sagaponack, and Sayre Pond and Cooper’s Neck Pond in Southampton.
Health officials have asked residents not to use, swim, or wade in those waters and to keep pets and children away. The advisory will remain in effect until the concentration of blue-green algae meets the state threshold and the water is not visibly discolored for at least 24 hours.