Katrina Takes Environmental Toll

"I didn't want to leave New Orleans," Doley said, carrying a duffel bag after getting off a rescue boat with her friends. "As long as they kept bringing us water, we didn't want to leave. We kept telling them to go help other people."

With tens of thousands taken out of the city in recent days, rescuers said there was a dramatic drop in the number of survivors found Tuesday.

"We're just seeing fewer and fewer people," said Larry Gillian, a paramedic volunteer from the North Arkansas Regional Medical Center. "The two people we brought in today, we've been after for the last couple days to come in and they wouldn't come. . . . Then they saw their friends come in and decided to come in themselves."

Gregory J. Smith, director of the National Wetlands Research Center for the U.S. Geological Survey in Lafayette, La., who was helping in search-and-rescue efforts, warned that parts of the city will be uninhabitable once the waters recede.

"There are concerns about hotspots for disease and for environmental hot spots," Smith said. "Some people left before the storm, some people left right after the storm and there are some people who will only leave under desperation, and that's where we are now."

Although levels have continued to drop in some areas, authorities only began concerted efforts to pump floodwaters into Lake Pontchartrain after plugging the biggest levee breach on Monday.

Only three out of 148 pumps in the New Orleans pumping station are operating, and it could take 80 days before the city and its outlying suburbs to the east are dry, according to Gordon Nelson, an assistant Louisiana transportation secretary. In the city's 17th Street Canal, which had been the site of the most serious break, only 9 cubic feet per second is being pumped out, compared with a potential capacity of 4,600 feet per second, Gordon said.

U.S. Army Corps of Engineers representative Dan Hitchings said 34 portable pumps were being installed, with more on the way.

Tuesday brought the first sign that the number of evacuees housed in hundreds of shelters nationwide may begin to fall off, with the Department of Homeland Security reporting about 180,000 shelter residents, down from about 230,000 the day before. Officials in several states said evacuees are leaving shelters once friends and family members can take them in.

At the same time, the number of storm victims seeking assistance continued to climb. FEMA said more than 360,000 individuals and families had applied for state and federal disaster relief by Tuesday afternoon. That number includes about 270,000 in Louisiana, 70,000 in Mississippi and 26,000 in Alabama, according to FEMA spokeswoman Mary Margaret Walker.

In the first formal assessment of the environmental devastation wrought by Katrina, state authorities in Baton Rouge announced a litany of contaminants likely to be found in the floodwaters, including tens of millions of pounds of concrete, lumber, cars, animal carcasses and all the other solid waste of a major metropolitan area.

Most sewage-treatment plants in New Orleans were destroyed. Two major spills sent 78,000 barrels of oil into Lake Pontchartrain, and fuel has coated the city from 2,200 fuel tanks and leaking gasoline from flooded cars and boats.