Northport Harbor, seen here on July 1, received a poor...

Northport Harbor, seen here on July 1, received a poor rating in terms of water quality in this week's report. Credit: Newsday/John Keating

Long Island's bays, harbors, rivers and inlets received a mixed assessment this week via the Long Island Water Quality Report, which has not observed mostly "good" conditions at its 29 test sites for more than a month.

As of this week's sampling, 10 out of 29 shore locations were rated good, meaning clear water, adequate oxygen levels and no or low levels of algae and/or bacteria from human or animal waste, making for hospitable conditions for fish and shellfish. Fifteen sites were rated fair, and four, poor.

The water quality report is a weekly score card issued from Memorial Day to Labor Day. It is created by Chris Gobler, professor of marine science at Stony Brook University and director of the New York State Center for Clean Water Technology, and his team of more than 20 students and scientists.

At seven sites located between Hempstead and East Hampton, oxygen levels surpassed 4.8 milligrams per liter; two came in between 3 and 4.8 milligrams per liter, and the readings for the remaining 20 areas were below 3 milligrams per liter, according to the report.

Bacteria are the sole marine life that can live without oxygen, according to the report. Dissolved oxygen levels should top 4.8 milligrams per liter, and never fall below 3 milligrams per liter, the report quoted the New York State Department of Environmental Conservation as saying.

Port Jefferson and Mount Sinai had good water quality. Further west, conditions were fair in Huntington Harbor, Oyster Bay, Cold Spring Harbor and Stony Brook Harbor, where there were "low levels of oxygen at night, reduced water clarity, and elevated levels of algae," the report said.

Even worse was Northport Harbor, which was rated poor, as oxygen levels at night fell below one milligram per liter, water clarity was reduced, and there were algae blooms that might harm marine life though not people, the report said.

recommendedLong Island water quality

As the summer temperatures warm seawater, it holds less oxygen, so "it takes only a slight disturbance in the natural balance of the ecosystem for oxygen levels to get dangerously low at night," the report said.

South Shore bays mostly had fair water quality, including Hempstead Bay and regions from Central Great South Bay through Shinnecock Bay, with reduced water clarity and oxygen levels and elevated levels of algae, the report said.

In contrast, the area in and around the Fire Island Inlet, including South Oyster Bay and western Great South Bay, were rated good by the report. 

Two South Shore areas — the Forge River and eastern Moriches Bay — were all tainted by algae blooms, "a complete absence of oxygen at night and poor water clarity," with their water quality assessed as poor, the report said.

Swimmers and those going fishing first should consult county health departments and the DEC for more details about where those activities are allowed, the report advised.

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