Long Island Sound Experiences Remarkable Recovery
Long Island Sound is showing signs of rejuvenation. The shared body of water between New York and Connecticut has reported its lowest hypoxia levels in almost four decades, leading to hopes for a revival in marine wildlife, including dolphins and whales.
Hyoxic pockets, which are areas with dangerously low oxygen levels, now cover only 18 square miles of the 1,300-square-mile sound. This is a marked decrease from about 430 square miles noted in 1987, when researchers began monitoring these levels.
“Fish were dying in significant numbers, and lobsters were trying to escape by crawling out of the water,” noted Peter Linderoth, director of healthy waters and lands at Save the Sound. “Animals were essentially suffocating due to the lack of oxygen,” he added, emphasizing the dire situation in the past.
Despite the challenges, Linderoth described the current state of Long Island Sound as a remarkable success story, one that he hopes will continue to unfold positively.
This significant improvement was highlighted recently in the Connecticut Department of Energy and Environmental Protection’s Year 2025 report on water quality monitoring.
The primary cause of past hypoxia was largely unregulated sewage and stormwater runoff. Fortunately, efforts in recent years have focused on improving the situation, with regulations mandating that wastewater treatment plants reduce nitrogen output.
Linderoth acknowledged, “The trend is encouraging. It’s a good sign, but we still face challenges. Let’s not underestimate that.” The largest concentrations of “dead zones” remain in the western area of the sound, especially near the border with Nassau County, where some locations still experience zero oxygen levels.
It’s worth noting that the study did not assess smaller waterways, such as the infamous Harlem River, which is substantially polluted.
The reduced hypoxia is already attracting marine life, with reports of nearly 70 dolphins sighted in the strait this summer.
Tricia Leicht, who played a role in establishing Save the Sound, recounted her experience of being surrounded by dolphins off the coast of New Rochelle. “They were jumping all around us,” she said, reflecting on the overwhelming sight that moved many on board to tears. “For everyone on that boat, it was a transformative experience,” she commented, adding that despite spending nearly 60 years on the water, this was her first encounter with dolphins in Long Island Sound.
In previous years, she often witnessed large numbers of bunker fish wash ashore, desperately attempting to escape the hypoxic water. She reminisced about how teenagers in the 1980s would jump into foam-filled patches in the sound. “It seemed amusing back then, but we didn’t understand that it was a sewage issue,” Leicht admitted.
While the progress regarding hypoxia is encouraging, environmentalists caution that global warming could potentially reverse these gains. They urge those who love the sound to help by minimizing nutrient runoff into wastewater. Simple actions like using less fertilizer, cleaning up after pets, and ensuring that storm drains remain unobstructed can make a difference.
