The U.S. Environmental Protection Agency (EPA) has ordered corporate giant General Electric to dredge toxic pollutants out of a 64 kilometer stretch of the Hudson River, north of New York City. It's considered one of the biggest - and most controversial - environmental cleanups in U.S. history.

The proposal, made in the waning days of the Clinton Administration, requires the General Electric company to remove more than 45,000 kilograms of polychlorinated biphenyls from the bottom of a section of the Hudson River north of Albany, New York, the state capital.

General Electric dumped PCBs, which have been linked to cancer and genetic damage, into the river from the 1940s until 1977 when the government banned the use of the chemicals. The cost of dredging the bottom of the river is estimated at about $500 million.

In a news release commenting on the decision, General Electric says the company "has invested $200 million in Hudson River research and restoration projects over the past 20 years and has met every commitment made to state and federal regulators. This has led to a remarkable improvement in the river during this period."

GE says the river is cleaning itself by burying the PCBs under successive layers of silt. But Robin Bell, a professor of earth science at Columbia University, says changes in the river itself can cause PCB's that are safely buried today to re-emerge tomorrow.

"Despite the fact that we have run a lot of models and a lot of money gets spend every year, we still do not know how much PCBs would get sent down the river if we had a hurricane that went straight up the Hudson, if we had what we call a 'hundred-year storm' that went right up through the middle and would cause massive erosion and flooding. If it is gone, it cannot happen," said Professor Bell.

One of the plan's most vocal opponents is Republican Congressman John Sweeney, whose congressional district includes the area to be dredged. His spokesman, Kevin Madden, says there is no question that the Hudson needs to be cleaned up. But Mr. Madden says the scope and method of the current plan will have a negative effect on the ecology and residents of the area, killing fish and intruding on people's property.

"It effects the economy because of the simple fact that you are going to have what is the equivalent of the 'Big Dig' on the Hudson River," he said, referring to a massive Boston highway construction project. "They are going to be taking out tons of sediment, PCB-laden sediment, out of the river. It is going to essentially turn what is supposed to be an environmental construction project into an environmental destruction project," said Mr. Madden.

Rich Schiafo, a representative of Scenic Hudson, one of the environmental groups that led the battle to clean up the Hudson admits there will be some ecological disruption. But he says the long-term impact of the decision is more important.

"In the long run we will have a much cleaner, safer, healthier river and a river that will be able to bounce back much more quickly and be less contaminated." said Mr. Schiafo. "Right now we have a very unhealthy ecosystem - PCB-contaminated fish, PCB-contaminated river otters, PCB-contaminated eagles. We get that PCB-contaminated sediment out of there and we let the river rebound without PCBs in it and we are going to have a much healthier ecology in the long term."

The EPA has modified the original plan somewhat so the dredging will be done in stages. But Kevin Madden says the changes do not ease concerns about storing the toxic materials once they are removed from the river. "They have never adequately addressed the topic of where the de-watering sites would go, what they would do once these PCB-laden sediments would go once they are brought out of the river," said Mr. Madden. "They have never actually addressed that and how that would effect the environment around the area."

But Scenic Hudson's Rich Schiafo says the Environmental Protection Agency plans to dispose of the hazardous waste in pre-existing landfills far from the area. "There are existing hazardous landfills that are designed to take this type of material. It is much better to have it in that type of facility than to have it at the bottom of a river with water flowing in it and over it and leaking out into the environment on a regular basis," he said.

Friends and foes alike agree that the clean-up will take years. The Environmental Protection Agency says the engineering design for the project will start next month and take a year. And it is still not clear whether the government or General Electric will do the actual work on the project.