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By Nicholas Spangler - June 3, 2021
For the first time, a peer-reviewed study has documented sustained increased levels of dissolved oxygen in the Long Island Sound, environmental officials said, a sign of improving marine health they hailed as encouraging if rare.
The Sound's low-oxygen zones, which may have depleted stocks of fish, crustaceans and other marine life, shrank from about 393 square miles in 1994 to about 52 square miles in 2018. The study by University of Connecticut scientists Michael Whitney and Penny Vlahos attributed much of the improvement to cuts in nitrogen, a pollutant, entering the Sound from wastewater treatment plants. Those cuts were crucial in combating the effects of warming water temperatures that would have otherwise lowered oxygen levels, the study found.
"This is proof that work done in the past is bearing fruit," said Mark Tedesco, director of the Long Island Sound office of the Environmental Protection Agency, who credited work by Suffolk and Nassau counties to reduce nitrogen pollution but said more work needed to be done in replacing or upgrading septic systems and reducing runoff from fertilizers.
"The good news is that restoration efforts are working," said Adrienne Esposito, director of Citizens Campaign for the Environment. "The bad news is that climate change necessitates that we do a lot more."
A May 26 news release from the Long Island Sound Study estimated that pollution controls had kept about 50 million pounds of nitrogen from entering the Sound annually during the study period, when billions of dollars were invested to upgrade treatment plants. The resulting water quality improvements led to "one of the few documented recoveries to a nutrient-caused hypoxic coastal system worldwide."
Nitrogen and other substances like phosphorus are nutrients, but when they wash into waterways they cause algae to grow rapidly, choking aquatic ecosystems and contributing to a condition known as hypoxia, or oxygen deficiency.
The threshold for hypoxia is 3 milligrams of dissolved oxygen per liter of water. The study found dissolved oxygen increasing at a rate of 0.48 milligrams per liter per decade despite warming of the Sound’s water. Warm water holds less oxygen than cold.
In Suffolk County, where three-quarters of homes are unsewered, officials in 2019 unveiled a $4 billion plan to combat nitrogen pollution by replacing cesspools with high-tech sewage systems that do more to remove nitrates. About 90% of Nassau County is connected to a public sewer system; officials there are using grants to help homeowners and small business owners replace failing septic systems.
In a news release, Rep. Thomas Suozzi (D-Glen Cove) called the University of Connecticut study findings "good news for everyone looking forward to enjoying this summer on the Long Island Sound. Let’s keep moving forward." Suozzi said while he was mayor of the City of Glen Cove from 1994 to 2001, the city’s wastewater treatment plant cut its nitrogen load in half.
The study’s authors warned, though, that the improvements to the Sound’s health achieved by cutting nitrogen pollution "will not be sustained in the warming climate without continued intervention."
President Joe Biden's budget request for the next fiscal year calls for $40 million to protect and restore the Long Island Sound, money Citizens Campaign called "critical to continue vital progress" in a release Thursday.