Skip to main content

Long Island Sound Water Quality Improves

Long Island Sound Map

Officials from the U.S. Environmental Protection Agency are reporting improved water quality in Long Island Sound because of almost 50 million pounds of nitrogen pollution being kept out of the Sound annually.

A peer-reviewed study published by the University of Connecticut earlier this year showed that the improvement in water quality is due to programs in Connecticut and New York to upgrade wastewater treatment plants so that nitrogen is removed before treated sewage reaches the sound.

“Water quality in Long Island Sound is improving thanks in large part to dramatic reductions in nitrogen pollution, which is great news for the Sound’s ecosystem and local communities,” Walter Mugdan, EPA Region 2 acting regional administrator said in a statement. “We have seen tremendous success in New York State’s work to keep nitrogen from reaching the Sound in treated sewage, which will have a lasting impact for years to come.”

Since the 1990s, the two states have worked with EPA to implement a nitrogen pollution reduction plan – known as a Total Maximum Daily Load plan — to improve the sound’s dissolved oxygen levels and to protect aquatic animals and the environment.

In past years, concentrations of dissolved oxygen in Long Island Sound waters decline to levels that are unhealthy for fish and other aquatic life. Low levels of DO — known as hypoxia — occur in the bottom waters of the western and sometimes central portions of the sound.

Hypoxia results when excess nitrogen fuels the growth of algae blooms. Bacteria feeding on the algae deplete the water of oxygen and marine organisms such as fish, crabs and lobsters must find healthier waters. Species that cannot move away, such as shellfish or worms, are harmed or perish.

Through infrastructure investments of more than $2.5 billion to improve wastewater treatment, the total annual nitrogen load to Long Island Sound is now some 47 million pounds less than the yearly discharge in the early 1990s. The area of hypoxia, based on a five-year rolling average, was 94 square miles in 2020, compared to the previous average of 205 square miles before the plan went into effect.

EPA New England acting regional administrator Deborah Szaro said: “Using science to inform our decisions, while maintaining a strong partnership with the states of Connecticut and New York, helps us continue to protect and restore the Sound, as well as plan for future action.”

EPA will continue to work with Connecticut and New York to further reduce nitrogen pollution in the Long Island Sound estuary.

Click here for a chart with the year-by-year measurement of the hypoxic area of Long Island Sound since 1987; or find more information here



Mass. Opens Office of Outdoor Recreation

The new office will coordinate outdoor recreation policy, identify funding opportunities and more.


OneWater Marine Completes Acquisition

Harbor View Marine has a marina facility in Pensacola, Fla., and a dealership in Orange Beach, Ala.


Florida Panhandle Marina Reopens

Destroyed by Hurricane Michael in 2018, Point South Marina in Port St. Joe has new drystack storage and is adding slips.


Wakesports Luminaries Recognized

The 2022 class of Wakesports Hall of Fame inductees includes influential pioneers from the sport’s earliest years.


Sea Tow Holds Annual Meeting

The company presented awards in a variety of categories, including the Captain Joe Frohnhoefer Visionary Award, named for Sea Tow’s founder.


Four Winns Launches Electric Boat

The builder partnered with Vision Marine Technologies on the H2e, a production bowrider powered by an electric outboard.