Major wastewater and infrastructure investments in Connecticut and New York appear to be producing measurable results, according to a new report documenting continued gains in Long Island Sound water quality.
Save the Sound’s 2026 Long Island Sound Report Card found that conditions either improved or held steady in each of the Sound’s five open-water regions.
The Western, Central and Eastern basins each earned an A, while the Eastern Narrows received a B.
The most notable change occurred in the Western Narrows, the area encompassing waters near New York City, which earned a D.
Despite that grade, the result represents the Western Narrows’ first passing mark since Save the Sound began evaluating the region in 2008. Before this year, it had received an F annually.
The Western Basin rose from A- to A, while the Central Basin advanced from A to A+.
The Eastern Basin held its A+ rating, and the Eastern Narrows remained at B.
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The report’s assessment of water quality considers dissolved oxygen, chlorophyll, clarity, dissolved organic carbon and the health of seaweed communities.
Researchers also track temperature, salinity, oxygen saturation and aquatic vegetation, along with the other indicators used to evaluate conditions in the Sound.
Too much nitrogen can trigger algae blooms and create oxygen-depleted waters, threatening fish and other aquatic organisms.
Save the Sound credited reductions in nitrogen pollution as a key reason water quality has improved across the Sound’s open waters.
Launched in 2017, Save the Sound’s Unified Water Study was designed to provide a clearer picture of conditions in 52 bays and harbors throughout the Sound.
The initiative uses common monitoring methods, equipment and protocols, allowing data gathered by different organizations to be compared across the region.
Still, Save the Sound cautioned that climate change, warmer water temperatures and increasingly severe stormwater runoff could undermine the progress reflected in the latest report.
The organization said sustained nitrogen reductions, along with continued spending on wastewater and stormwater systems, will be essential to preserving the Sound’s gains.