Environment

Eastern Long Island Sound earns high grades in latest water quality report

Long Island Sound earned an A+ and A on its latest report card related to water quality.

The high grades issued in Save the Sound’s 2020 report represent the “Eastern Basin” east of Riverhead past Orient Point (A+) and the “Central Basin” from Port Jefferson to Riverhead (A).

But as has been the case in past studies, the water quality of the Sound deteriorates farther west.

The report, issued Oct. 6 at a press conference in Oyster Bay, showed the “Western Basin” from Port Jefferson to Northport received a B grade. The “Eastern Narrows” from Northport to about Hempstead Harbor received a C. And by New York City, the water quality deteriorated to an F.

The Eastern Basin had also received an A+ grade in its last report in 2017.

“Water quality has been stable over the past 12 years, never dropping below an A,” the report states. “This region has a much lower coastal population with large tracts of undeveloped land. Being adjacent to the ocean, it has strong tidal exchange.”

The Central Basin’s “water quality has been stable over the past 12 years and in consistently supportive of marine life,” the report says. “It’s the largest area of open water contained in the report card and is well-flushed with water from the Atlantic Ocean.”

The report for the first time was expanded to include water quality grades and findings for 50 bays and bay segments in Long Island Sound, in addition to open-water testing. 

The highest grades were the eastern parts of Long Island Sound. (Credit: Save the Sound)

Tracy Brown, the regional director of water protection for Save the Sound, said this was done with the help of 22 groups around the Sound, including the Group for the East End and Cornell Cooperative Extension.

Save the Sound now has two years of results from these bays and creeks, but overall,the results weren’t good. 

“We have two years of consistent data on Long Island Sound’s bays and the results are sobering,” Ms. Brown said. “Many of the bays in the Sound are stressed and the predicted impacts of climate change and population growth in our region will only exacerbate current issues and potentially create more in the future.”

Only two bays from the North Fork were rated. Mattituck Creek received a B- grade, and Goldsmith Inlet in Southold received a B grade. 

By comparison, B wasn’t that bad. 

“Only 44% of the bays and bay segments received a grade of B or above,” the report states. “Nearly half (48%) received poor grades of D or below for dissolved oxygen levels, an important measure of water quality,” the report states, adding that low dissolved oxygen (hypoxia) can lead to fish and other marine life die-offs.

Another concerning finding was poor grades resulting from excess seaweed as well as algae floating in the water, which are caused by nitrogen pollution entering the Sound from coastal and upstream communities. 

Excessive seaweed was cited as a concern in Mattituck Inlet and Goldsmith Inlet, as was chlorophyll a, which measures the amount of phytoplankton in the water column. 

Further, the report revealed that the quality of nearby “open-water” in the Sound does not always predict the quality of water in adjacent bays, with important ramifications for environmental health.

“Nitrogen pollution remains a major threat to a healthy Sound,” said professor Jamie Vaudrey of the University of Connecticut, who is an advisor on the report card. “Our stressed bays, which experience marine life die-offs and algae blooms, are telling us that it’s more critical than ever before that communities continue to reduce nitrogen input and other nutrient pollution.”

Save the Sound is a nonprofit environmental organization based in Mamaroneck, N.Y. and New Haven, Conn.