New Orleans Mayor C. Ray Nagin says a new wall of water is expected to flow into the east bank of the city beginning around 8:30 a.m. or 9 a.m., causing floods of nine feet or more in some areas.
"This is the bowl effect that everyone has been talking about," said Nagin. "Water is now going to fill the bowl on the east bank."
Nagin told CBS affiliate WWL-TV that flood experts have told him that the new deluge, caused by the failure of a flooded pump at a levee with a break some two blocks wide at the 17th Street Canal, will continue until the water is at three feet above sea level: the same level as Lake Pontchartrain, the huge salt water lake on the city's northeast border.
Since New Orleans itself is below sea level, that means the flooding is expected to be enormous on many streets - the degree depending on how many feet below sea level each street is.
On famed St. Charles Street, that would mean nine feet of water.
The French Quarter, which was not devastated by Hurricane Katrina's original impact on Monday, is expected to be affected by the new floods, as is the city's uptown section.
Nagin had hoped to have Army Blackhawk helicopters drop 3,000-pound sandbags on the levee at Pumping Station No. 6 before it became too waterlogged to continue operating. That, he says, "didn't happen" because there were too many chiefs calling the shots in responding to the disaster, he told WWL-TV.
"My heart is heavy," said Nagin, as he ticked off New Orleans' current problems: no electricity, for at least four to six more weeks; contaminated drinking water; gas leaks sending flames shooting up from beneath the water; bodies floating in the water; a leaking oil tanker which ran aground; two bridges gone; both airports flooded; and no clear path in or out of the city.
Rescuers in boats and helicopters are continuing to pluck shocked and bedraggled flood survivors from rooftops and attics. More than 3,000 people have been rescued by boat and air, some placed shivering and wet into helicopter baskets. They were brought by the truckload into shelters, some in wheelchairs and some carrying babies, with stories of survival and of those who didn't make it.
Louisiana Gov. Kathleen Blanco said Tuesday that the tens of thousands of people now huddled in the Superdome - which is now surrounded by knee-deep water - and other rescue centers will have to be evacuated.
"Everybody's scared, worried, desperate, and the living conditions there are horrible, so we're moving them out and trying to give them a little bit of ease," Blanco told CBS News Early Show co-anchor Julie Chen.
The city is also without drinkable water. Other problems:, and a large group of inmates sitting on a highway watched over by relatively few guards, after being evacuated from a flooded prison.
An untold number of people are feared dead in Louisiana. "We have no counts whatsoever, but we know many lives have been lost," said the governor.
"We've fought hurricanes before. You know, we think we are hurricane-smart and there's some normal things that go on during the aftermath of a serious hurricane, but this is not normal. This is past the normal thing that we normally have dealt with over the years," Blanco said.
Nagin says hundreds, if not thousands, of people may still be stuck on roofs and in attics, and so rescue boats are bypassing the dead.
A congressional delegation is expected to do a flyover Wednesday for a preliminary assessment of the situation.
By midday Tuesday, Katrina was downgraded to a tropical depression, with winds around 35 mph. It was moving northeast through Tennessee and there are concerns that over the next few days, it could swamp the Tennessee and Ohio valleys with a potentially ruinous 8 inches or more of rain.
In Katrina's wake across the Gulf Coast, millions of people are still without electricity: at least 370,000 homes and businesses in Louisiana, at least 900,000 homes and businesses in Mississippi, and about 718,000 homes and businesses in Alabama.
In Alabama, two people were killed and the property damage is heavy, in some areas appearing worse than the impact of Hurricane Ivan last year. The flooding in Mobile matched a record set in 1917 and a major bridge there remains closed, after being struck by an oil drilling platform that floated away from a shipyard.
In Mississippi, authorities say the confirmed death toll for Harrison County - home to devastated Gulfport and Biloxi - has topped 100 and is expected to rise.
"We are very, very worried that this is going to go a lot higher," said Joe Spraggins, civil defense director for Harrison County, home to Biloxi and Gulfport. "We're just estimating but the number could go double or triple from what we're talking now."
"What I'm authorized to say now is we expect the death toll to be higher than anything we've ever seen before," said Jim Pollard, a colleague of Spraggins.
Bill Lokey, an official with the Federal Emergency Management Agency, called Katrina "the most significant natural disaster to hit the United States."