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Cyanobacteria Blooms found in Agawam Lake in Southampton and Lake Ronkonkoma

Lake Ronkonkoma Beach Closed to Bathing

Sampling performed by SUNY Stony Brook has confirmed the presence of new cyanobacteria blooms, more commonly known as blue–green algae, in Agawam Lake in Southampton and Lake Ronkonkoma.  There is one regulated bathing beach on Lake Ronkonkoma (Islip Beach) which is closed to bathing as because of this cyanobacteria bloom.  In addition, cyanobacteria blooms are still present in Laurel Lake in Laurel, Maratooka Lake in Mattituck, Roth Pond at SUNY in Stony Brook, Mill Pond in Watermill, and Wainscott Pond in East Hampton. 

Due to these findings, health officials ask residents not to use or swim or wade in these waters and to keep their pets and children away from the area. 

Though blue-green algae are naturally present in lakes and streams in low numbers, they can become abundant, forming blooms in shades of green, blue-green, yellow, brown or red. They may produce floating scums on the surface of the water or may cause the water to take on paint-like appearance. 

Contact with waters that appear scummy or discolored should be avoided. If contact does occur, rinse off with clean water immediately.  Seek medical attention if any of the following symptoms occur after contact: nausea, vomiting or diarrhea; skin, eye or throat irritation; or allergic reactions or breathing difficulties.

To report a suspected blue-green algae bloom at a body of water that contains a Suffolk County-permitted bathing beach, contact the Suffolk County Department of Health Services’ Office of Ecology at 631-852-5760 between 8:30 a.m. – 4:30 p.m. or by email at any time at

To report a suspected blue-green algae bloom that is in a body of water that does NOT contain a Suffolk County permitted bathing beach, contact the Division of Water at New York State DEC at 518-402-8179 between 8:00 a.m. – 4:00 p.m. or anytime via email at or use the NY HAB system:

For a comprehensive list of affected waterbodies in New York State, visit the DEC’s Harmful Algal Bloom Notification Page at or the NY HAB system:

For more information about blue-green algae, as well as other harmful algal blooms, visit the Suffolk County website:

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