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A floating tractor that has been used the last two summers to skim thick clumps of aquatic weeds out of Georgica Pond may be helping the pond to avoid the dense blooms of toxic algae that appeared in previous years, a marine scientist told the East Hampton Town Trustees this week.
Dr. Christopher Gobler of Stony Brook University told the Trustees on Monday night that in 2015 the pond saw a dangerously dense bloom of blue-green algae, which naturally emits a toxin that can sicken humans and kill pets that ingest it in pond water.
In the early spring of that year, there also had been a dense bloom of thick pond weeds earlier that year that had died off and started to decay, releasing large amounts of nutrients into the pond, possibly feeding the blue-green algae blooms.
But after the Friends of Georgica Pond, a community group formed in 2015 to muster an effort to clean up the pond, contracted for the use of an “aquatic harvester” to motor through the pond, removing the patches of floating weeds, Dr. Gobler said the algae blooms in the last two summers, while present, have not been as dense or as long-lived as they had been in some years prior.
“It seems to be having a beneficial impact,” he told the Trustees, saying that the theory of the spring explosion of weeds, which he calls macro-algae, feeding the summer blooms is a “working hypothesis,” with a number of other environmental factors to be considered as well.
Dr. Gobler also noted, as he has before, that the opening of the cut between the pond and the ocean has a clear impact on the algae blooms. The closer to the start of the summer that the cut and its influx of saltwater come, the later in the year the algae blooms appear. And if the pond is opened during a dense bloom, it quickly snuffs it out.
In his fourth annual report to the Trustees since the professor and his marine science lab were hired to conduct year-round monitoring of all town waters, Dr. Gobler told the board that East Hampton continues to see much better overall water quality than other areas of Long Island thanks to its proximity to the flushing tides of Gardiners Bay and Block Island Sound.
But in some areas where flushing is dampened by geographical features, and where groundwater tainted with nitrogen from human waste flows into harbors and creeks, the town still had its share of harmful algae blooms and high bacteria levels in 2017.
The worst of those areas, as it has been for several years, was again the Head of the Harbor region at the southern end of Three Mile Harbor.
The area is surrounded by densely developed residential neighborhoods, most of them made up of older houses with aging or failing septics, and has some of the highest levels of nitrogen influx in the harbor. Coupled with poor flushing because most of the southernmost corner of the harbor is cut off from the rest by a narrow channel, Head of the Harbor is home to the town’s poorest water quality.
But, Dr. Gobler said, it also may be the most ripe for a turn-around.
Because the area is low-lying and groundwater flows quickly into the harbor, reducing the amount of nitrogen being released into the ground in human waste could pay quick dividends in terms of stanching the flow of nutrients that feed algae blooms. Focusing town money on replacing septic systems in houses in the watersheds of Head of the Harbor could quickly change the dynamic at work, the scientist said.
“Rapid action could lead to rapid results,” Dr. Gobler said. “In Great South Bay, people say, it took decades to get into this problem, it will take decades to get out. That’s not true here.”
on Apr 24, 2018