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Pollution Lurks in 'Urban Sea'

Nutrients from sewage flows threaten water quality and kill fish; experts look for solutions. LONG ISLAND SOUND

THE waters of Long Island Sound look clear from this central part of the island where teens fish for small snapper. But looks do not always tell the full pollution story.At the center of debate over the seriousness of pollution in the Sound are questions about the effect of the heavy supply of nutrients pouring into its western part - and what, if anything, should be done about them. Their effect on low dissolved oxygen levels in deep water, a condition known as hypoxia, is the central focus so far in the massive, federally funded Long Island Sound Study (LISS), underway since 1985 and due to be completed next fall. Sometimes called "the urban sea," Long Island Sound sits in the most densely populated region of the United States. Each day 1 billion gallons of treated sewage from plants in New York and Connecticut flow into the Sound. When rainfall is high and sewers overflow, raw sewage and rain water go in, too.

Studies show problems Many experts say that the added nitrogen from treated sewage can damage or kill fish and shellfish in bottom waters or force them to flee to areas where oxygen is more abundant. Hypoxia occurs naturally to some degree in summer as warm surface water forms a distinct layer over colder bottom water, and oxygen in surface water is prevented from replacing that used by marine life below. Added nutrients can speed up and intensify the oxygen loss by fueling the growth of single cell marine plants in surface w aters. When the algae dies and drops to the bottom, it uses scarce oxygen there as it decomposes. In an interim report issued late last year, the LISS, a study overseen by the US Environmental Protection Agency, urges that treatment plant discharges of nitrogen into the Sound be restricted to 1990 levels. Environmentalists say the recommendation should include a timetable. "We think the process of capping nutrients should be started now so that we aren't continually increasing the amount of nitrogen that goes into the Sound," says Jane Moffat, coordinator of the Long Island Watershed Alliance. It is a coalition of 60 groups that grew out of a series of National Audubon Society hearings on the Sound last year. "We should at least keep the situation from getting any worse," agrees Jeff Kane, program coordinator of the Citizens Campaign for the Environment and a member of the LISS Citizens Advisory Committee. Yet he says the study has spent too much time, money, and energy on hypoxia and not enough on other pollutants such as toxic chemicals and pathogens. Other recent studies confirm that such problems exist. A National Oceanic and Atmospheric Administration study of coastal waters found chemical contamination declining in many areas but still serious in urban areas such as the Western Sound. A recent Natural Resources Defense Council report claims the coastal waters of New York, Connecticut, and New Jersey have the worst bacterial contamination problem in the US, due largely to outdated sewage treatment systems. LISS officials insist that other pollution problems will be studied before the final report is issued. Mr. Kane is also critical of what he sees as the study's emphasis on engineering solutions and development of computer models: "Ultimately it's the residents ... that cause the problems and are going to have to change their lifestyles." Cities around the Sound are taking steps that may help. Some, including New York City, plan to build holding tanks to store storm water until it can be treated along with regular sewage. Some communities are limiting new sewer hookups. Others are looking at new ways to get nitrogen out of treated sewage. Some remedies are very costly. Upgrading New York City sewage plants to tertiary treatment levels, for instance, could cost as much as $6 billion. City officials insist that nitrogen discharge levels from city plants have remained stable for 40 years and question the cost benefit ratio. "Before you make a multibillion dollar investment, you ought to have a better notion of the return; we need to keep looking constantly for different solutions," says J.R. Schubel, dean and director of the Marine Sciences Research Center at the State University of New York at Stony Brook and a member of the LISS technical advisory committee. Just last week the research center held a workshop that included talk of other options: tidal locks along the East River to keep sewage effluent from moving directly into the Sound, installation of long pipes so that treated sewage is discharged only into distant, deeper waters, and the possible use of aerators to recharge the water with oxygen. Dr. Schubel and William Wise, associate director of the Marine Center, stress that there is nothing inherently wrong with adding nutrients. "Most of the ocean is underfertilized," insists Schubel. Mr. Wise suggests that overfishing may pose more of a problem for marine life in the Sound than hypoxia. He says much more needs to be known about how specific dissolved oxygen levels translate into a direct effect on marine life. Also key, he says, is knowing whether low oxygen levels in the Sound are really d eclining or just holding steady.

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Sound solutions needed Environmentalists point to the summer of 1987 when there was a particularly intense bloom of algae and sample trawls of LISS scientists brought up no bottom-level fish in some areas and a high percentage of dead crabs and starfish. Yet Mr. Wise notes that the problem has not resurfaced. Schubel says that research should never be used as an excuse to delay needed action, but he adds that the Sound's pollution problems are complex and deserve carefully chosen, long-term solutions. He says it is important to cap nutrient input from sewage treatment plants in New York and Connecticut, as the interim report of the LISS urges, but also to take action to protect the central and eastern Sound which he says are still in "remarkably" good condition. "It's always a lot cheaper and more effective t o protect an environment that's still in good shape than to let it go and rehabilitate it."