To the estimated 10,000 residents still believed to be holed up in this ruined city, the mayor had a blunt new warning: Get out now -- or risk being taken out by force.
As floodwaters began to slowly recede with the city's first pumps returning to operation, Mayor Ray Nagin authorized law enforcement officers and the US military to force the evacuation of all residents who refuse to heed orders to leave.
Police Captain Marlon Defillo said that forced removal of citizens had not yet begun.
"That's an absolute last resort," he said.
Nagin's order targets those still in the city unless they have been designated as helping with the relief effort. Repeated calls to Nagin's spokeswoman, Tami Frazier, seeking comment were not returned.
The move -- which supersedes an earlier, milder order to evacuate made before Hurricane Katrina crashed ashore Aug. 29 -- comes after rescuers scouring New Orleans found hundreds of people willing to defy repeated urgings to get out.
They included people like Dennis Rizzuto, 38, who said he had plenty of water, food to last a month and a generator powering his home. He and his family were offered a boat ride to safety, but he declined.
"They're going to have to drag me," Rizzuto said.
That's a sentiment Captain Scott Powell, of the South Carolina Department of Natural Resources, has heard before as he tries to evacuate people by air boat.
"A lot of people don't want to leave. They've got dogs and they just want to stay with their homes. They say they're going to stay until the water goes down," he said.
In Washington, President George W. Bush and Congress pledged Tuesday to open separate investigations into the federal response to Katrina and New Orleans' broken levees.
"Governments at all levels failed," said Republican Senator Susan Collins.
The pumping began after the Corps used hundreds of sandbags and rocks over the Labor Day weekend to close a 60m 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.
Although toxic flood waters receded inch by inch, only five of New Orleans' normal contingent of 148 drainage pumps were operating, the Army Corps of Engineers said.
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.
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.
There were at least 124 prisoners in a makeshift jail set up at the city's train and bus terminal.