The swirling outer tentacles of Hurricane Rita sent white water rushing Friday over makeshift dikes that had been hastily built after Hurricane Katrina, reflooding the low-lying urban neighborhoods that were devastated nearly a month ago.

Rising waters cascaded over at least three breaches in patched-up temporary levees Friday morning, inundating the Ninth Ward of New Orleans and much of St. Bernard Parish. Those areas were ghost towns after Katrina, so almost no one was endangered by the flooding, and most of the property in its path had already been destroyed last month.

But Rita was still hours from landfall Friday night, with winds of only 25 mph in New Orleans, so higher storm surges may be on the way when the hurricane hits the shore. And when water pours over levees for extended periods, it tends to scour them out, which lets in even more water.

"This was the one we were all watching," said Maj. Gen. William B. Caldwell IV, the commander of the 82nd Airborne Division, watching helplessly as water from the roiling Industrial Canal sloshed over the recent levee repairs. "We tried driving up in our Humvees, but we couldn't get to it," he said, noting that the water was three feet deep in some parts of the Ninth Ward by midday.

"If the regular floodwalls were in place, they wouldn't have a problem," said G. Paul Kemp, an oceanographer at Louisiana State University's Hurricane Center. "But the temporary levees were basically gravel. They didn't have a chance."

After Katrina broke through concrete floodwalls along the 17th Street, London Avenue and Industrial canals, Army Corps of Engineers contractors plugged the gaps with boulders and crushed aggregate, and barricaded the entire 17th Street and London Avenue canals near Lake Pontchartrain with sheet piling. In recent days, Corps officials had expressed confidence that the rock piles would hold off Rita, even though they were six feet shorter and much less sturdy than the original floodwalls. Hurricane experts have suggested that the walls that collapsed during Katrina were poorly designed or badly built.

The sheet piling that blocked off the 17th Street and London Avenue canals did hold Friday, so Lake Pontchartrain did not pour into the city as it had done during Katrina. But Rita's driving rain and fairly modest winds did pour a steady flow of water from the Gulf of Mexico over low points on both sides of the repaired Industrial Canal levees -- and through one 30-yard breach on the east side. There were also failures in a smaller dike protecting St. Bernard Parish, which had lost much of its protection during Katrina.

Corps Col. Richard Wagenaar said Rita's storm surges were larger than predicted in New Orleans; his agency had been told to expect two to five feet. "That clearly wasn't the case." He said it would set back repairs at least three weeks.

Katrina had drowned the impoverished Lower Ninth Ward, but most of the city had been drained. The Lower Ninth was buried in rubble and caked in mud, but it was dry. Caldwell was preparing to go home.

Instead, Caldwell and his men tried driving to the dikes in Humvees on Friday, but the water was too high. The Corps tried to plug one of the breaches with a tractor-trailer, but the lift truck sank into a hole. A helicopter that was supposed to drop sandbags had maintenance problems, and the main water pump in the Ninth Ward had been destroyed by Katrina. Streets that were wiped out last month, then painstakingly reconstructed over the past few weeks, were once again turned into canals. Several feet of new water swirled around homes that were still marked by a layer of muck resembling a second-story bathtub ring.

One police officer said he had seen a few holdouts in the Lower Ninth, but most of the areas underwater Friday were almost entirely empty except for rescue workers. When New Orleans Mayor C. Ray Nagin invited residents to start returning to their homes last week, before changing his mind under heavy pressure, he was not talking about the Lower Ninth, where most of the homes that were not carried off their foundations or bulldozed into rubble are not habitable.

Katrina flooded 85 percent of this city and claimed 841 lives in Louisiana at last count. New Orleans was drained much faster than expected, thanks to 37 auxiliary pumps augmenting the 70 or so city pumps that were operating, Caldwell said. "That's why the water went down so rapidly," he said. "We were getting ready to go home."

At the Florida Avenue bridge leading into the upper Ninth Ward, a street made passable early this week was once again a lake Friday afternoon with canal water lashing up onto the east side of the bridge.

Standing atop the Florida Avenue bridge, Dale Stapleton, a maintenance unit supervisor for the Corps, eyed another small breach in the levee close to the New Orleans shipyard. "We're trying to get some equipment through this city and to that location," he said. "We hope to get some rock and sandbags in -- whatever we could use."

But a second round of repairs to the major breaks will have to wait until Rita passes. Twenty helicopters positioned at Fort Rucker in Alabama -- a 70-minute flight from New Orleans -- will drop sandbags into the gaps when the weather improves, probably Saturday afternoon, Caldwell said.

About 6,500 members of the 82nd Airborne remain in New Orleans and will assist with a new round of search-and-rescue efforts.

Meanwhile, in Washington, Sen. Pete V. Domenici (R-N.M.), the chairman of the Appropriations energy and water subcommittee, joined Senate Minority Leader Harry M. Reid (D-Nev.) in pushing the White House to spend more money on Corps water projects. Within a few hours of the levee breaches, Domenici and Reid had fired off a letter to Joshua B. Bolten, director of the Office of Management and Budget, requesting an additional $1.7 billion for the Corps.

"The renewed flooding in New Orleans just proves that Congress and the White House cannot be penny wise and pound foolish with the Corps and its mission right now," they wrote.

But Wagenaar said the problem with his agency's patched-up levees was not a matter of money but a matter of time. Three days ago, the Corps had hired a contractor to raise the temporary levees two to three more feet -- but the work had not yet been begun.

Grunwald reported from Washington.

Water pours through a levee on the Inner Harbor Navigation Canal in New Orleans as wind and rain from Hurricane Rita batters the stricken region.