Four weeks after Hurricane Katrina emptied this city of its 470,000 people, New Orleans remains a deserted shell, struggling to restore basic services, patch up tattered levees and pump out floodwaters as business owners and residents of the Algiers neighborhood prepared to return for a second time Monday.

Hurricane Rita pushed the New Orleans recovery effort back by about five days, Mayor C. Ray Nagin said. But he is determined to resume a reentry plan that federal officials have questioned as too ambitious, given the fragility of the city's utilities, hospitals and traffic controls.

"We want to bring New Orleans back," he said, acknowledging that the process will begin only with healthy, hardy adults. "We're talking about people who are mobile. We're not asking people to come back who have a lot of kids, a lot of senior citizens. That's going to be the reality of New Orleans moving forward."

After evacuating for Rita last week, crews trickled back into New Orleans on Sunday to find much of their work had been undone. In the wealthy Garden District, tree removal experts hauled away limbs and branches from streets that had been cleared. Utility trucks returned to reconnect power in the city's West Bank -- and body recovery resumed, although state officials said the Katrina death toll remained at 841.

Most significantly, teams from the U.S. Army Corps of Engineers descended on the deep, wide Industrial Canal to repair temporary levees damaged by Rita. Working through the night Saturday, the Corps dropped 200 sandbags -- weighing between 3,000 pounds and 7,000 pounds -- into the largest breaks, spokesman Mitch Frazier said. It probably will take a week to pump out the lower Ninth Ward that was submerged for two weeks by Katrina and flooded again by Rita over the weekend. That would be faster than expected, as officials had projected it would take two weeks.

Even with those rapid repairs, the Corps does not expect the city's levee system to return to pre-Katrina levels until June.

With nearly two months remaining in hurricane season, "we should be eternally worried until the levee structure has been repaired to pre-Katrina heights," Coast Guard Vice Adm. Thad W. Allen said on CNN's "Late Edition."

This week, Nagin hopes to name a high-profile commission to oversee the reconstruction of a city that faces heart-wrenching decisions about whether to rebuild in neighborhoods that were underwater not once but twice.

"Some of these houses are going to be uninhabitable, but the public does not know that yet," Allen told "Fox News Sunday." "In my personal discussions with the mayor, I think he's desirous to have the public have a good appreciation for the condition of the city and then take next steps. That may not be explicitly stated, but that is my understanding."

Allen, named by President Bush to oversee the New Orleans recovery, publicly chastised Nagin a week ago when the mayor announced an ambitious plan to invite as many as 280,000 people back into the city over a week's time. This time, Nagin is pledging a more gradual approach.

"We will begin the reentry plan with business owners and residents of Algiers," he said Saturday. "Then we will stop, assess our progress and move on to the previously targeted Zip codes."

Even as Nagin pressed ahead, officials acknowledged that a severe financial crunch is affecting teachers, the district attorney's office, hospital workers and the police. Schools are not expected to reopen before January.

The Orleans Parish district attorney's office announced it would lay off more than half its "non-essential, non-legal" staff primarily because the city of New Orleans has been unable to make its quarterly payment to the office. A statement warned: "Further layoffs may be required without additional funding."

The city received $102 million in immediate salary assistance, but under federal rules the money may be used only for overtime.

"We don't know how we'll pay base salaries," Nagin said. Police officers were paid last Friday, but the mayor said it will be difficult to make the next payroll.

The Louisiana State University health care services division, which runs a network of hospitals across the state, has pledged to pay workers through October. The system lost nearly half its revenue when Katrina demolished its flagship Charity Hospital in downtown New Orleans and is in danger of losing staff members, chief executive Don Smithburg said.

As thousands of residents and workers return to the New Orleans area, "there's going to be a dire need for health care," he said in an interview Sunday. When that happens, "we're going to need those staff members, and health care workers are a precious, precious commodity these days."

One less positive sign of a return to normal: New Orleans police made 11 arrests Saturday night. Capt. Marlon DeFillo, a police spokesman, said they were minor incidents, though he could not provide details. The city has a makeshift jail in the bus-train station under Interstate 10.

City police officers, many left homeless by Katrina and then evacuated from temporary housing on a cruise ship during Rita, gathered in a hotel meeting room for a worship service Sunday.

Referring to insurance companies and the Federal Emergency Management Agency, 5th District Capt. Bruce Adams addressed 80 or so colleagues and hotel workers.

"State Farm and FEMA are not the way to restore our life," he said. "Jesus Christ is the way to restore more than we had before."

Staff writer Susan Schmidt in Washington contributed to this report.