Every working day, the barges laden with noxious wastes head for a spot in the Atlantic, 12 nautical miles off Long Island.
There New York City and eight neighboring municipalities - the only communities in the nation that still dispose of waste at sea - dump 28 tons of sewage residue, industrial chemicals, dredged harbor mud and ash.
In this summer of frequent beach closings and mysterious dolphin deaths, environmentalists and New York and New Jersey state officials are debating the wisdom of ocean dumping with renewed vigor.
In the search for explanations, the environmentalists point to the ocean waste. But state officials point out that, for now, with the region in the midst of a growing garbage disposal crisis, ocean dumping may unfortunately be the best alternative.
In addition to a heavy concentration of fecal bacteria, much of the material being dumped off Long Island is either too toxic to be put in landfills, the officials say, or there is simply too much of it to be dumped on land - just as there is a scarcity of disposal sites for more routine household and industrial waste.
That shortage may account for the illegal dumping earlier this month of several tons of hospital waste, including used syringes with needles, that closed some New Jersey beaches.
New Jersey investigators concluded last week that the dumping was a "deliberate illegal act," probably committed by a regular trash hauling company. They said they were concentrating their investigation on two haulers, but declined to name them.
Governor Kean has offered a $5,000 reward for information leading to conviction of the illegal dumper, but environmentalists say the continued legal dumping of waste in ocean waters presents a far greater hazard to human and marine life than the occasional illegal dumper.
"I think the effects of dumping are obvious," said Valerie Maxwell, a leader of Clean Ocean Action, an environmental group in Sea Bright, N.J., that opposes ocean dumping.
So far, the environmentalists acknowledge, most of the evidence is circumstantial, but they believe that a study being conducted by the New Jersey Health Department will find a link between the legal ocean dumping and sickness among swimmers.
"Our waters are closed to shellfish harvesting"' Ms. Maxwell said. "We are beginning to get documentation that people can get sick by swimming in the water. The dolphins are dying. If we walked outside and found 200 dead dogs and cats, we'd get pretty involved in trying to find out what was happening to our animals."
State and Federal officials are confident that the problem will lessen as the close-in dumping grounds are closed by the end of this year and dumping is moved to a new site, already used by New York and others, 106 nautical miles off New Jersey in water about one and a half miles deep. The limited dumping at the 106-mile site is proceeding under a temporary permit while the United States Environmental Protection Agency considers applications for long-term permits.
But Ms. Maxwell's group and such national groups as the Environmental Defense Fund and the American Littoral Society argue that any ocean dumping should be stopped, particularly since the rest of the country's shore communities have done so.
Ms. Maxwell called ocean dumping "barbaric," and E.P.A. officials in Washington noted that other coastal urban areas, most recently Los Angeles and Boston, had managed to end such disposal by cleaning waste sufficiently to put it in landfills.
The issue of ocean pollution has been of concern in New Jersey this year because of a record number of serious beach pollution incidents.
The State Environmental Protection Department has counted 14 beach closings in the state, including four major incidents such as the medical waste washed ashore in Ocean County earlier this month and the sudden rise in fecal coliform bacteria off Atlantic City last week, which closed beaches there for the first time.
For the whole of last year's swimming season there were 12 closings, all for short times and involving limited stretches of beach, and none because waste and debris had washed ashore.
Sewage sludge has been dumped outside New York Harbor since the 1920's. In 1972, Congress voted to ban ocean dumping, and with the adoption of this law, all other municipalities in the country have stopped the practice. But by arguing among other things, that the waste is too toxic to put on land and that there is no space to put it anyway, New York City and eight other municipalities won a court decision allowing them to continue ocean dumping.
Since then, over a billion tons of sewage sludge, wood ash, industrial acids and harbor mud have been dumped into the relatively shallow 80-foot depths 12 miles off Long Beach, L.I.
"You can do three things with sludge," said James Staples, a spokesman for New Jersey's Environmental Protection Department. "You can dump it in the ocean, put it on land somehow or incinerate it.
"Until New Jersey gets to the point where it can have adequate pre-treatment of industrial sewage, it's too shot full of heavy metals to be used in a land application, and it may be too tough to incinerate, too. So even though we are professionally and culturally opposed to it, the least of the evils is ocean dumping."
Officials point out that the ocean is not the only source of shore contamination. Street runoff and flooded or broken sewers can sweep so many germs into the water that the New Jersey Health Department has started requiring routine closing of beaches after heavy rains.
Under prodding from an environmental health group, the State Health Department is also surveying beachgoers to determine whether ocean swimming is responsible for a reported outbreak of minor infections last year. A group of physicians and other health workers called Save Our Shores has said it documented the outbreak last year, which it blamed in part on ocen sewage sludge dumping.
The dumpers are New York City; Westchester and Nassau Counties in New York, Bergen, Middlesex Rahway, Sussex and Union Counties in New Jersey, and Passaic and Linden-Roselle, N.J.
The sludge's rich nutrients promote the growth of organisms that deplete the oxygen available for fish and other forms of marine life. The fecal coliform bacteria occasionally finds its way into coastal waters and forces the closing of beaches. Unburned timbers and other solid material wash onto beaches.
Any solution involving land disposal of sewer sludge - the material left over from normal sewage treatment -would involve expensive additional treatment to remove the toxic wastes. But while groups like Clean Ocean Action call for laws requiring industries to pretreat their own sewage, state officials recognize the political difficulties of handing local businesses such an expensive task.
"It's a powerful argument," said Mr. Staples of the New Jersey Environmental Protection Department, "but as you can imagine, the industries involved are just as powerfully arrayed against any rules that would cost them that much."