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Cyanobacteria Blooms found in Excess in Ponds in Riverhead and Southampton

Analysis of surface water samples performed by SUNY Stony Brook has confirmed the presence of recent cyanobacteria blooms, more commonly known as blue–green algae, in South Merrits Pond in Riverhead and Mill Pond in Southampton.

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

Avoid contact with waters that appear scummy or discolored. 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. to 4:30 p.m. or by email at any time at To report a suspected blue-green algae bloom to the New York State Department of Environmental Conservation (NYSDEC) at a body of water that does NOT contain a Suffolk County permitted bathing beach, email

To view a map of all affected fresh waterbodies in New York State, visit NYHABS. Email questions to

For additional information about blue-green algae, as well as other harmful algal blooms, visit the following websites:

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Categories: Health


Suffolk County Government

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