New data from studies measuring pollution in Hempstead Bay indicate water there is laden with nitrogen and awash in treated effluent from five nearby sewage plants.
Experiments show the nitrogen fuels growth of algae and seaweed, according to Stony Brook University scientist Larry Swanson. Other results demonstrate that effluent seems to get bottled up for days in the shallow bays behind Long Beach, instead of flushing out quickly to the ocean. Swanson briefed local officials, advocates and residents on the findings at a meeting in Mineola Thursday.
Those results - which researchers stressed are still preliminary - echo what some have been saying for years about declining water quality in the complex of marsh islands and channels known as the Western Bays.
"Some of us have waited eight years to hear what you've just heard," said Adrienne Esposito, executive director of Citizens Campaign for the Environment and a member of the committee guiding the research.
But the confirmation didn't comfort some residents, who expressed frustration at how long it had taken to address the problem. Others asked for more frequent tests of water quality near the outfall for the Bay Park treatment plant, which processes nearly half Nassau's sewage and was found this fall to have been illegally discharging treated sludge to Reynolds Channel.
"How does a sewage treatment plant get to that state of disrepair?" asked Peter Suchmann of Oceanside.
The studies were launched last fall to measure contaminants in Hempstead Bay and analyze the effects on water quality, marshes and marine life. Their final conclusions, expected in the winter of 2012-13, will help the state Department of Environmental Conservation set pollution limits for the bays.
New York classifies the Western Bays as "impaired" because of pathogens from contaminated runoff. The DEC more recently listed nitrogen as a suspected contaminant that may trigger overgrowths of seaweed; likely sources include sewage and stormwater runoff.
Thus far the experiments have borne out that second link - nitrogen as aquatic fertilizer - said Swanson, associate dean of Stony Brook's School of Marine and Atmospheric Sciences.
Researchers also tested bay sediments for sewage-related contaminants found in fabric softener, cosmetics and other personal care products. Swanson said the concentrations in Hempstead Bay were as high as those found in New York Harbor and Jamaica Bay.
Esposito said even those findings, dire as they are, have an upside - they could qualify Hempstead Bay for grants to help fix the problem.
"We need this science in order to go to those federal programs and help this water body," she said.