By Tracy Brown, Director of Save the Sound

The non-profit organization Save the Sound released results of the 2018 “Long Island Sound Report Card.” The biennial report contained remarkable evidence of improvement in Long Island Sound water quality. The report marked a welcome stamp of approval for more than a decade’s worth of federal and state investment in improvements to sewage treatment facilities in Connecticut and New York.

Save the Sound staff cautioned that individual beaches and bays face continued challenges (testing monitored “open water” conditions only), that the westernmost portion of the Sound remains stressed, and that climate change and population growth pose challenges requiring additional investment. Nonetheless, staffers and scientists alike were gratified to see proof that investment in water quality is paying dividends.

The most positive results were found in the measurement of dissolved oxygen in the Sound, a crucial barometer for the health of the waterway. Low levels of dissolved oxygen (hypoxia) can lead to fish die-offs, reduced reproduction of marine life, and other adverse conditions. Improvements to sewage treatment plants in the region have reduced the discharge of nitrogen to the Sound from those plants by 58.5% which, in turn, reduces the depletion of oxygen in the waterway and supports marine life.

For the first time, the Report Card includes 10 years of data and an assessment of how water quality is trending in each region of the Sound. Year-to-year (or even multi-year) fluctuations in water quality can be influenced by weather conditions and other factors, so scientists are wary of identifying a trend until numerous years of data from water quality measurements are available. The 2018 Report Card includes evidence that dissolved oxygen levels, the focus of coordinated conservation efforts, have improved over the past 10 years.

The region where the improvement is the most dramatic is the Eastern Narrows, which spans the entire open coastline of Westchester County, NY to Darien, CT on the north, and the open coastline of Nassau County to Asharoken, NY on the south side of the Sound. This region went from a “D+” in 2008 to a “B-” in 2017, benefitting from both the upgrades made to its local wastewater treatment plants and those made to plants on the East River, which flows into the western end of the Sound.

Water quality in the Sound is now a far cry from conditions in the 1980s, when a steady increase in population and poorly treated sewage led to harbors full of dying fish and shellfish, dirty beaches, and waters almost devoid of oxygen. By 2000, the U.S. Environmental Protection Agency (EPA), the New York State Department of Environmental Conservation (NYSDEC), and the Connecticut Department of Energy and Environmental Protection (CTDEEP) agreed to make a significant investment in a clean and healthy Sound. More than two billion dollars were invested over the following 16 years to treat nitrogen at dozens of sewage treatment plants that discharge to the Sound, ultimately achieving a 58.5% reduction in the amount of nitrogen entering the Sound from those plants.

In many respects what we’re seeing is a victory for the tenets of the Clean Water Act, as well as the commitment shown by New York and Connecticut officials, the EPA, and citizens alike. We now have hard evidence that investment in improved technology at treatment plants pays great dividends. The most important step now is to recognize that there is more work to be done – both to keep from sliding backwards in the face of climate change and population pressure, but also to move forward so that the most heavily populated areas of the Sound share in the recovery.

In fact, the Western Narrows, home to New York City, have remained stalled at an “F” grade (45%) since 2008. The area is densely developed, heavily populated, and has very little exchange with the Atlantic Ocean, so is still suffering from nitrogen pollution stemming from human waste and stormwater runoff. However, even this most challenging part of the Sound showed significant improvements in dissolved organic carbon in the 10-year data, leading to a sense of optimism for scientists involved in the study.

The “grades” for Long Island Sound’s water quality have gotten better in the last decade, but one area in particular remains in need of improvement. ©

“This latest Report Card shows strong evidence that reducing nitrogen loads from sewage treatment plants has been effective in improving water quality throughout the main stem of Long Island Sound,” said Dr. Jason Krumholz, senior environmental scientist at McLaughlin Research Corporation, a science advisor for the Report Card. “However, many of the bays and harbors surrounding the Sound have not shown the same pattern of water quality improvement, and require additional study. The ongoing Unified Water Study hopes to shed light on the drivers of water quality improvement in these areas.”

In addition to dissolved oxygen, the report measured water clarity, chlorophyll a levels, and dissolved organic carbon. Overall, the Report Card revealed:

• The Eastern Basin received an A+ (100%). This region’s water quality has been consistently excellent over the past decade.
• The Central Basin received an A (96%). Conditions have been consistently supportive of marine life over the past decade.
• The Western Basin received an A- (92%). This region has shown notable improvement in water quality, as the summer zone of low oxygen continues to shrink.
• The Eastern Narrows received a B- (82%). This region still needs to improve its dissolved oxygen levels, although overall water quality has improved significantly.
• The Western Narrows received an F (45%). This part of the Sound is still suffering from nitrogen pollution stemming from human waste and stormwater runoff; however, significant improvements in the DOC indicator could be a sign of things to come in future Report Cards.

The Long Island Sound Report Card was produced by Save the Sound and published in September 2018 using 2008 – 2017 data. Funding was provided by the Long Island Sound Funders Collaborative. Science direction was provided by Jamie Vaudrey, Ph.D. and Jason Krumholz, Ph.D.

Save the Sound encourages area residents to take their own actions to reduce the amount of nitrogen entering the Sound from fertilizers and the roughly 500,000 septic systems in coastal communities. More information on the report and steps individuals can take to help improve Long Island Sound water quality is available at