Blue-green algae blooms, long a problem in many freshwater bodies on the East End, have turned toxic this spring.
The Suffolk County Health Department is urging people to keep their pets and children away from Lake Marratooka in Mattituck, Lake Agawam in downtown Southampton and Big Reed Pond near Shagwong Point east of Lake Montauk, which have all recently tested positive for high levels of toxic cyanobacteria by the New York State Department of Environmental Concentration.
Blue-green algae blooms are often caused by a combination of high levels of phosphorus and nitrogen, sunlight, warm weather and stagnant water, according to the DEC. At high concentrations, the algae can also deprive ponds of oxygen, causing widespread fish deaths, as has happened in the past in South Fork ponds with high algae levels.
Though not all blue-green algae is toxic, the health department reported Monday evening that all three East End ponds contain a known liver toxin that can cause nausea, vomiting or diarrhea; skin, eye or throat irritation, allergic reactions or breathing difficulties. The health department is urging anyone who experiences these symptoms after coming in contact with an infected pond to seek medical attention.
Dr. Christopher Gobler of Stony Brook Southampton, an authority on algae blooms, said in his State of the Bays address earlier this year that the Centers for Disease Control have found 368 cases throughout the country where they know dogs have died after drinking water from a pond with toxic blue-green algae in it, including one dog on Long Island in 2012.
Dr. Gobler also said that, while most pond algae blooms are caused by excess phosphorous, the toxic strains are prompted by excess nitrogen.
Toxic blue-green algae was found in Marratooka Pond last fall, and widespread but non-toxic strains of the algae were found in both Lake Agawam and Water Mill’s Mill Pond throughout last summer.
The three East End ponds and Blue Heron Lake in Westchester are the only water bodies in the state listed by the DEC as having elevated levels of blue-green algae this week.
In high concentrations, blue-green algae blooms can look green, blue-green, yellow, brown or red, and may cause floating scum on the surface of the water or may cause the water to look like thickly colored paint.
The health department is urging residents who notice an algae bloom at a Suffolk County-permitted bathing beach to contact the health department’s office of ecology at 631.852.5760, and to report blooms at non-bathing beaches to the DEC’s division of water at 518.402.8179.