NEW ORLEANS – Progress was measured in inches Tuesday, in the slow dropping of water levels outside New Orleans' buildings, as engineers struggled to drain this saucer of a city in a herculean task that could take weeks — if they are lucky.

The Army Corps of Engineers said the timetable ranges from three weeks to nearly three months, depending on a string of variables, including rainfall, the still-unknown condition of the pumps abandoned to Hurricane Katrina, and whether the system can withstand the flotsam of broken buildings, trees, trash and corpses.

"We have to get the water out of the city or the nightmare will continue," said Louisiana Environmental Secretary Mike McDaniel. He said the water will be pumped into Lake Pontchartrain even though it is fouled with sewage, heavy metals, gasoline and other dangerous substances.

The pumping began after the Corps used hundreds of sandbags and rocks over the Labor Day weekend to close a 200-foot gap in the 17th Street Canal levee that burst in the aftermath of the storm and swamped 80 percent of this below sea-level city.

Following an aerial tour Tuesday, Mayor Ray Nagin said the water was dropping ever so slightly, and he estimated that it covered only 60 percent of the city.

"Even in areas where the water was as high as the rooftops, I started to see parts of the buildings," he said, adding, "I'm starting to see rays of light."

But he also warned of the horrors that could be revealed when the waters recede. "It's going to be awful and it's going to wake the nation up again," said Nagin, who a day earlier upped his estimate of the death toll in his city to as much as 10,000.

The job got off to a woefully slow start.

Once all of the city's pumping stations are running, they can move water at a rate of 29 billion gallons a day and lower the water level a half-inch per hour, or about a foot per day. But by late Tuesday afternoon, Corps officials said only three of New Orleans' normal contingent of 148 drainage pumps were operating.

With the water dropping, military and police turned their attention to evacuating the streets of the estimated 10,000 people still believed to be in the city. Some have been holed up in their homes for more than a week and refuse to leave.

"You've got to protect your property, that's the main thing," said 69-year-old John Ebanks, who waved off would-be rescuers from a porch stocked with food, mosquito spray and other supplies. "This is all I've got. I'm pretty damn old to start over."

In a plea to holdouts who might be listening to portable radios in the powerless city, Nagin warned that the fetid water could carry disease and that natural gas was leaking all over town.

"This is not a safe environment," Nagin said. "I understand the spirit that's basically, 'I don't want to abandon my city.' It's OK. Leave for a little while. Let us get you to a better place. Let us clean the city up."

To that end, the Pentagon began sending 5,000 paratroopers from the Army's storied 82nd Airborne Division to use small boats, including inflatable Zodiac craft, to launch a new search-and-rescue effort in flooded sections of the city.

Some National Guardsmen and helicopters were diverted from their search missions Tuesday to fight fires, an emerging threat in a city that is still at least a day and a half away from restoring the first running water since the storm.

A candle was blamed for starting one major blaze in the lower Garden District — a historic neighborhood of mostly wooden homes. The flames started in an abandoned brick building and spread to a neighboring apartment house. The blazes burned for hours before Chinook helicopters with water pouches were brought in to fight the blaze.

New Orleans Police Superintendent Eddie Compass said lawlessness in the city "has subsided tremendously," and officers warned that those caught looting in an area where the governor has declared an emergency can get up to 15 years in prison. About 124 prisoners filled a downtown jail set up at the city's train and bus terminal.

"We continue to get better day by day," Compass said.

The signs of hope came against increasingly angry rhetoric over the federal response as too little too late. In Washington, congressional leaders planned hearings into the aftermath of the storm.

"We need to rebuild the confidence of the American people ... in our government's ability to protect them from attack, whether it comes from nature or from terrorists," said Sen. Joseph Lieberman, D-Conn. "The government simply did not act quickly and effectively enough."

Jefferson Parish president Aaron Broussard was even more blunt.

"Bureaucracy has murdered people in the greater New Orleans area," he said on CBS' "Early Show." "Take whatever idiot they have at the top of whatever agency and give me a better idiot. Give me a caring idiot. Give me a sensitive idiot. Just don't give me the same idiot."

Five of the 13 sub-basins in New Orleans were still seriously flooded, and barges and crews were getting into place to fix levee breaches at two other spots — the London Avenue canal and the Industrial canal. The London Avenue canal is in the northwestern section of the city, the Industrial canal in the east.

The levees were deliberately breached in some spots to let the water flow back out into Lake Ponchartrain, where the water level had dropped below that inside the city.

How long it takes to drain the city could depend on the condition of the pumps — especially whether they were submerged and damaged, the Corps said. Also, the water is full of debris, and while there are screens on the pumps, it may be necessary to stop and clean them from time to time.

"We're working every avenue to do whatever we can to get things back in order," said Walter Baumy, Corps manager for the project. "We're going to accomplish the mission of getting the water out of the city."

Associated Press reporters Doug Simpson, Dan Sewell, Jim Litke, Melinda Deslatte and Randolph E. Schmid contributed to this report.