Elevated levels of a blue-green algae that produces toxins harmful to people and animals have been found in an East Hampton pond, nearly two years after a dog died from drinking the water there during an algal outbreak.

Christopher Gobler, a professor at Stony Brook University's School of Marine and Atmospheric Sciences, said his laboratory discovered the elevated levels of blue-green algae in Georgica Pond last week, in addition to moderate to high levels of Anabaena, another cyanobacteria that also produces toxins.

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East Hampton Town trustees issued a letter last week advising the public to avoid swimming and wading near the blooms and drinking the water, and recommended keeping children and pets away from the area.

The trustees also moved to prohibit the taking of crabs, shellfish and other marine species from the pond until Aug. 12 as a precaution.

Blue-green algal blooms occur when cyanobacteria overgrow in a water body. The bacteria produce toxins that can cause allergic reactions, gastrointestinal upset and other symptoms in people and animals, according to the Suffolk County health department.

In 2012, a Jack Russell terrier died after drinking from Georgica Pond during a blue-green algal bloom.

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In addition, Mill Pond in Water Mill and Wickapogue Pond in Southampton Village both have confirmed blooms with high levels of toxins, while Lake Agawam in Southampton Village and Lake Marratooka in Mattituck each have confirmed blue-green algal blooms, according to a list maintained by the state Department of Environmental Conservation.