Signs posted at the Town of Brookhaven's Michael J. Murphy...

Signs posted at the Town of Brookhaven's Michael J. Murphy Beach at Lake Ronkonkoma warn of harmful blue-green algae in the water. (Aug. 5, 2013) Credit: Newsday / John Paraskevas

A blue-green algae bloom triggered by a type of bacteria that last year killed a Jack Russell terrier has been found in Lake Ronkonkoma, Long Island's largest freshwater lake and a popular swimming spot.

The algae was found last week in two spots along the south shore of the lake, which straddles the borders of Islip, Smithtown and Brookhaven towns, but beaches were found to be safe for swimming as of Friday, state officials said.

"The health department and local officials regularly evaluate the safety of the beach for swimming, and there can be times when the blooms are found in one part of the lake, but the beaches can be clear for swimming," said Peter Constantakes, state Department of Environmental Conservation spokesman.

Suffolk County Department of Health Services, which monitors bathing beaches, advised Islip Town to close Lake Ronkonkoma Beach on July 29, but lifted the notice Friday after toxin levels were low, spokeswoman Grace Kelly-McGovern said.

Warning notices were given to Islip and Brookhaven, which does not have a permitted swimming beach.

Signs warning about the algae were posted near the water at Lt. Michael P. Murphy Memorial Park in Brookhaven, advising people not to swim, wade or fish near blooms or surface scum. They also suggested people report to local health departments and seek medical attention "if you have symptoms of nausea, vomiting or diarrhea; skin, eye or throat irritation, allergic reactions or breathing difficulties."

The signs deterred some, but not others. Ivan Checkhov, 20, a Polish student attending LaGuardia Community College in Queens, was not worried. "I've been swimming in lakes forever so I don't think anything can get me," he said while wading in the water.

Emergency medical technician Darryl Smith, 40, turned around after reading the sign. "I'm not going in the water again, I'll tell you that much," he said.

Blue-green algae can turn water the color of pea soup or look like white, blue or green paint has been dumped. The Jack Russell terrier that drank from Georgica Pond in East Hampton last year tested positive for cyanobacteria, which triggers the blooms.

The blooms are fairly mobile, said SUNY School of Marine and Atmospheric Sciences professor Chris Gobler. "You can get them moving around via a wind event," he said. "At certain times of day, they may choose to migrate down."

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