The Long Island Sound's open waters are cleaner and clearer, the result of hundreds of millions of dollars spent removing nitrogen, though New York City still sends huge amounts of the algae-growing pollutant into the water, according to a report by a nonprofit.
"We're seeing that reducing nitrogen in waste water really does improve water quality," Tracy Brown, director of the Connecticut-based nonprofit Save the Sound, said by telephone. "We've got to make the investments, and then we'll have a vibrant, commercially productive Sound."
Wastewater system upgrades, which started in 2000, enabled New York State to cut its nitrogen pollution in the Sound by 58.5 percent in 2017, according to the report. That's two years after Connecticut hit this target, which the two states had agreed with the U.S. Environmental Protection Agency to meet.
"The cautionary tale is Florida," Brown said.
Toxic algal blooms on Florida’s east and west coasts have killed sea creatures and kept tourists away. Had New York and Connecticut not acted, Brown said, "That would be the news story we would be rolling out right now."
The Sound's star performer was the Eastern Narrows, which last year scored a B minus when its dissolved oxygen, water clarity, chlorophyll and dissolved organic carbon were measured. Lack of oxygen can kill fish and other marine life. Chlorophyll powers phytoplankton, a microalgae, while dissolved organic carbon is a proxy for sewage.
In 2008, that part of the Sound, just north of Hempstead Harbor, Oyster Bay, Oyster Bay Harbor, Cold Spring Harbor, and Northport, was rated a D plus. Further improvements partly depend on neighboring New York City, now in the midst of a three- to five-year planning phase for its wastewater plants, Brown said.
"We did see this big jump in the Eastern Narrows, which was very heavily influenced by ... wastewater treatment plants in that area, but also by New York City wastewater treatment discharges, which come in massive volumes," she said.
Once again, the area closest to New York City flunked, repeating the F it received in 2008. Called the Western Narrows, it runs from around the Robert F. Kennedy/Triborough Bridge to Sands Point.
Further out on Long Island, the Western Basin received an A minus, up from its previous B. This section spans Setauket Harbor, Flax Pond and Stony Brook Harbor.
The Central Basin, the northern boundary of Port Jefferson and Miller Place harbors, repeated its 2008 performance with an A. Similarly, the Eastern Basin, which stretches from Orient Point and along Plum, Great Gull, Little Gull and Fishers islands, again achieved an A plus.
Unlike the Sound's open waters, many of its bays and inlets are much less healthy, as they are closer to the sources of pollution and flushing by the tides is less vigorous, Brown said.
Treated sewage accounts for 33 percent of the nitrogen fouling the Sound, Brown said. Septic systems produce 20 percent, and fertilizer 14 percent.
Fossil fuels, produced by cars and coal plants, are the worst offender, depositing a total of 41 percent into the water and on the land through a process called “atmospheric deposition,” she said.