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Blue-green algae has been found in South Merritts Pond in Riverhead, the Suffolk County health department said in a press release last night.

The pond, located in a populated area between Roanoke and Ostrander avenues in Riverhead, is one of several water bodies in which the State Department of Environmental Conservation has confirmed a blooms of cyanobacteria, commonly known as blue-green algae.

Health officials urge residents not to use or swim or wade in these waters and to keep their pets and children away from the area.

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.

New cyanobacteria blooms have also been confirmed in Wickapogue Pond, Coopers Neck Pond, and Little Fresh Pond in Southampton and Babylon Town Hall Pond, the health department said. In addition, cyanobacteria blooms have re-emerged in Lake Ronkonkoma and Roth Pond on the campus of Stony Brook University. Cyanobacteria blooms are still present at Lake Agawam and Sagg Pond in Southampton, Mill Pond in Watermill, Georgica Pond in East Hampton and Artist Lake in Middle Island, the health department said.

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.

Physical and chemical factors contribute to the formation and persistence of cyanobacterial blooms in freshwater systems, according to the U.S. Environmental Protection Agency. These factors include: light availability, water temperature, alteration of water flow, pH changes and nutrient loading— both nitrogen and phosphorus. Runoff from lawns, roads and stormwater is often high in nitrogen and phosphorus and can promote or cause conditions favorable to the growth of blue-green algae. 

Locally, cyanobacteria blooms have previously been reported in Forge Pond, Peconic Lake and Laurel Lake.

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. and 4:30 p.m. by email.

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: 518-402-8179 between 8 a.m. and 4 p.m. or by email.

For a comprehensive list of affected waterbodies in New York State, visit the DEC’s Harmful Algal Bloom Notification Page.

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Denise is a veteran local reporter, editor and attorney. Her work has been recognized with numerous journalism awards, including investigative reporting and writer of the year awards from the N.Y. Press Association. She was also honored in 2020 with a NY State Senate Woman of Distinction Award for her trailblazing work in local online news. She is a founder, owner and co-publisher of this website.Email Denise.