Floodwaters are slowly receding in Australia's third-largest city, but the people of Brisbane and other flood-ravaged Queensland communities were warned Thursday that they face a recovery of "postwar proportions."

Floodwaters poured into more than 30,000 properties in the Brisbane area before the water level peaked early in the morning.

The swollen Brisbane River, which peaked at a lower level than expected, had already begun to recede by the afternoon, though water levels were expected to stay high for several days.

Queensland Premier Anna Bligh made an emotional appeal to people affected by the flooding, calling on residents of the northeastern Australian state to pull together after "the worst natural disaster in our history and possibly in the history of our nation."

Two men push their boat along a flooded street in a commercial area of Brisbane on Thursday. (Tim Wimborne/Reuters)

"We've seen three-quarters of our state having experienced the devastation of raging floodwaters and we now face a reconstruction task of postwar proportions."

"I said earlier this week that this weather may break our hearts, and it is doing that," she said, fighting back tears. "But it will not break our will and in the coming weeks and the coming months we are going to prove that beyond any doubt."

One man died in Brisbane when the muddy waters sucked him into a storm drain. The discovery of his body, and two others on Thursday, brought the death toll from flooding to 25 since late November.

Officials told Brisbane residents forced from their homes and businesses that it would be days before they could return, though no bans were in place preventing people from surveying the damage. Others were told their homes will never be habitable again.

Mayor Campbell Newman told reporters the cleanup effort in Brisbane will likely take "many, many months."

Death toll expected to rise

At least 61 people were still missing Thursday and police held "grave fears" for 12 people who disappeared when a wall of water tore through the Lockyer Valley west of Brisbane late Monday, the Australian Broadcasting Corporation said.

The flooded Brisbane River spills into residential areas close to the city's central business district, on right. (Tim Wimborne/Reuters)

Many of those unaccounted for disappeared from around Toowoomba, where Monday's flash floods swept away cars, road signs and people.

Fourteen died in that flood alone, with police finding the bodies of two of those people on Thursday. Ian Stewart, the deputy police commissioner, warned that the toll was likely to rise as search-and-rescue teams gained access to more devastated areas Thursday.

"We've got to brace ourselves for more bad news," Stewart said.

Meanwhile, officials in Brisbane were struggling to determine the scope of the flood damage.

Waters in some areas had reached the tops of roofs, shut down roads and power and devastated entire neighbourhoods, while other areas that had prepared for the worst were spared.

Newman said 11,900 homes and 2,500 businesses had been inundated, and another 14,700 houses and 2,500 businesses at least partly covered by water.

"Underneath every one of those roofs is a family, and underneath every single one of those rooftops is a horror story," said Bligh, who surveyed the damage in a helicopter.

The local utility said more than 77,000 customers were still without power in southeast Queensland, with most of the disruptions in Brisbane's south and west and around Ipswich.

Danny Donald, a spokesman for Energex, said crews were relying on boats to reach flood-affected areas.

"We're in the boat with everyone else, in that we've got a few access issues," he told the Australian Broadcasting Corporation. "I guess on the bright side we have actually reconnected around 80,000 customers since last night."

Despite the devastation, many in Brisbane were thankful the river running through the city had spared them the worst of its fury.

Lisa Sully, who lives in the nearby suburb of Sherwood, did have some water in her home — but she still felt lucky on Thursday.

"I can handle this," she said. "Mentally, I was prepared for worst."

The flooding across Queensland has submerged dozens of towns — some three times — and left an area the size of Germany and France combined under water. Highways and rail lines have been washed away in the disaster, which is shaping up to be Australia's costliest.

"Individual homeowners will probably be working at it for weeks or months," freelance reporter Stuart Cohen told CBC News. "But Queensland itself is going to have a couple of years of rebuilding."

"They're talking about probably two years really to rebuild," he said. "They've got to rebuild the infrastructure in some places from scratch."

The damage estimates was already at $5 billion before the floodwaters swamped Brisbane.

With files from the Australian Broadcasting Corporation and The Associated Press