Fresh Pond’s history of water quality

When Native Americans lived on the shores of Fresh Pond thousands of years ago, they dumped discarded scallop shells in the water.

Before the Shelter Island landfill opened in 1950s, Fresh Pond was the most popular dump site on the Island with everything from refrigerators to car batteries tossed into the drink.

But according to Tom Junod, who has been swimming in Fresh Pond for 17 years, water quality reached a new low last Sunday.

“It was the first time I looked and said, there is no way I’m going in that–milky-green water with scum piled up on the shore,” Mr. Junod said.

It’s been a tough year for Fresh Pond, Shelter Island’s only deep freshwater lake, with the  town putting up signs late last week cautioning against swimming.

Fed by the local aquifer, the pond is what geologists call a kettlehole, dug out by the receding glacier of the last Ice Age.

Putting refuse into Fresh Pond may be an Island tradition that goes back thousands of years, but it’s taken an especially toxic and widespread sort of pollution — nitrates from untreated sewage — to fuel the algae bloom that colored the water green in recent weeks and led to Monday’s posted warnings against any exposure of humans or animals to the potentially poisonous conditions in the water.

Town Engineer John Cronin, in a presentation to the Hay Beach Association two years ago noted that, “Nitrate pollution of the aquifer has been a known issue on the Island at least as far back as the 1980s.”

In addition to untreated sewage, harmful algae blooms (HABs) can be the result, according to the Department of Environmental Conservation’s website, of a combination of factors, including extended periods of still water, sunlight and high temperatures.

Monday afternoon the surface of the water was glass, reflecting sky and trees. A woman who said she was a visitor emerged from a minivan full of bathing-suited would-be swimmers, but decided against letting the kids out when she saw the warnings.

“What a shame,” she said. “It looks so beautiful.”