Nitrogen Pollution, the Long Island Sound Dead Zone and New York City Sewage Treatment Plants – Administrative Advocacy

Newtown Creek Wastewater Treatment Plant

Location: East River, New York City (Queens, Brooklyn, and the Bronx) | Status: Active 


Long Island Sound Dead Zone

When too much nitrogen is discharged into Long Island Sound, it creates low oxygen conditions, known as hypoxia, making it harder for aquatic life to survive. In some instances excess nitrogen creates zero oxygen zones, also known as dead zones. Some other impacts are toxic algal blooms, low dissolved oxygen, poor water clarity, loss of aquatic vegetation and tidal wetlands, and coastal acidification. Sewage treatment plants throughout the Long Island Sound watershed are the primary drivers of low oxygen and dead zones in the Sound. Other sources that contribute are stormwater runoff, fertilizers, and poorly performing septic systems.

The Total Maximum Daily Load plan was issued in 2000 to limit the amount of nitrogen discharged to Long Island Sound and begin to bring it back to health. This took the preliminary step of requiring nitrogen reductions from Connecticut and New York sewage treatment plants by almost 60 percent by 2014. This goal has now been largely achieved and has made the dead zone in Western Long Island Sound significantly smaller, but it has not been eliminated. Moreover, new nitrogen-based pollution challenges have emerged in our bays and harbors.

Save the Sound’s 2015 Nitrogen Petition

Thus, in 2015 (when the actions identified in the 2000 plan were supposed to have been achieved), Save the Sound petitioned EPA to create a new plan to further reduce nitrogen discharges and bring Long Island Sound back to full health. We argued that Long Island Sound continues to have dead zones each year and continues to violate federal water quality standards. The petition noted that future plans will have to extend beyond consideration of the Western Long Island Sound dead zone to address localized low oxygen zones and dead zones that exist in our bays and harbors throughout the Sound. At the same time, the petition pointed out that New York City sewage treatment plants remained a primary driver of the Western Long Island Sound low oxygen zone, and significant additional reductions would be needed.

After Save the Sound filed the petition and before ruling on it, EPA announced a far-ranging “Nitrogen Strategy for Long Island Sound,” which sought to achieve many of the goals we advocated for in the nitrogen petition. It set out three large goals to:

  1. further reduce the dead zone in Western Long Island Sound by further sewage plant reductions from the New York City area,
  2. reduce low oxygen zones and dead zones in our bays and harbors through localized action, and
  3. reduce nitrogen pollution entering Long Island Sound via major rivers such as the Connecticut and Housatonic.

Each one of these strategies would involve:

  1. characterizing how much excess nitrogen is contributing to the problem,
  2. determining the sources of nitrogen, and
  3. setting reduction targets for specific sources to achieve waterbody health.

Given EPA’s stated intention to fund and move forward with the Nitrogen Strategy, Save the Sound and our partners held the petition in abeyance pending the implementation of the strategy. While full implementation of the strategy has not happened as fast as we would have liked, significant progress has been made on all three fronts by reducing New York City discharges into the western dead zone, creating plans for harbors and bays, and addressing pollution from the upper Connecticut River.

In February 2022, Save the Sound filed formal comments urging DEC and EPA to impose meaningful additional nitrogen limits on the total discharge from six sewage treatment plants on the East River in New York City. Our comments were based upon the Clean Water Act’s requirement to set limits that will not cause or contribute to a violation of water quality standards and the science in the Nitrogen Strategy. The science shows, and the agencies have acknowledged, that the permitted levels of nitrogen discharge from the plants are leading to harmful algal blooms, loss of tidal wetlands and eelgrass, coastal acidification, and low oxygen in the East River and Western Long Island Sound. The discharges have caused or contributed to parts of the East River and Western Long Island Sound violating water quality standards 90-100% of years between 2014 and 2019. The agencies, however, are waiting for New York City to finish refined modeling that will inform long-term planning before taking action.

Ultimately, the agencies should require reductions by:

  1. requiring the four upper East River plants (Tallman Island, Bowery Bay, Wards Island, and Hunts Point) to use existing nitrogen technology to achieve further reductions, and
  2. requiring Newtown Creek to install nitrogen-reducing technology.

Once new modeling and science is developed, the permit may be reopened to impose final, more refined long-term nitrogen limits. Save the Sound issues a Long Island Sound Report Card that characterizes the chronic poor water quality conditions in western Long Island Sound due to the New York City wastewater treatment facilities and other sources[1]. This portion of Long Island Sound has received an F for water quality every year from 2008-2019.

[1] “Long Island Sound Report Card.” Save the Sound,

Next step: Continue to document low oxygen and other polluted conditions in Western Long Island Sound due to New York City sewage treatment plants and advocate for opening and modifying of the NYC permit when new modeling is available.   

Further reading:

Action opportunities:

Last Updated: November 16, 2022

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