Flood water in Australia's third-biggest city peaked below feared catastrophic levels on Thursday but Brisbane and other devastated regions faced years of rebuilding as a fresh flood threat loomed with a cyclonic storm building off the coast.

The capital of Queensland state resembled a muddy lake, with an entire waterfront cafe among the debris washing down the Brisbane River, a torrent that has flooded 12,000 homes in the city of 2 million and left 118,000 buildings without power.

With 35 suburbs flooded, many parts of Brisbane looked more like Venice as residents used boats to move about flooded streets, where traffic signs peeped above the stagnant water.

It's a swimming pool, said Ian Parker as he walked in ankle-deep water through his house, which sits on stilts but looked like it was afloat.

Like many flood victims, Parker was stoical as he inspected his waterlogged home: It's a lot better than other people.

Aerial views of Brisbane showed a sea of brown water littered with rooftops.

What I'm seeing looks more like a war zone in some places, Queensland Premier Anna Bligh said as dawn revealed the overnight devastation.

All I could see was their rooftops ... underneath every single one of those rooftops is a horror story, she told reporters after surveying the disaster from the air.

This morning as I look across not only the capital city, but three-quarters of my state, we are facing a reconstruction effort of post-war proportions, Bligh said.

An emotional Bligh said her state, reliant on farming and mining in rugged outback regions, would recover regardless of the cost and estimates that three quarters -- an area the size of South Africa -- was now officially a disaster zone.

Officials warned of the real risk of further severe flooding in the coming weeks, with two months of the wet season ahead and already overflowing dams requiring seven days to empty to normal levels to cope with more heavy rains.

The Bureau of Meteorology said a monsoonal storm in the Coral Sea off Queensland's north coast was expected to form into a cyclone in 24 to 48 hours, but while it would bring fresh rains to Queensland it was expected to move away from the coast.

Queensland has received so much rain in the past two months the ground is fully waterlogged and dams are full, meaning any more heavy rain will simply exacerbate already flooded rivers.

HOMES LOST IN BROWN FLOODS

billion in damage from the deluge that began last month in Queensland, crippling the coking coal industry and destroying roads, railways and bridges.

The deadly floods have killed at least 19 people and 61 are missing, according to revised figures. Toowoomba and the Lockyer Valley region, west of Brisbane, have been completely devastated, with whole towns unrecognisable.

But the water peaked at almost a metre below the level of deadly 1974 floods in Brisbane. Authorities said a protective dam built after that tragedy had helped spare the city from the expected worst-case scenario this time.

Despite that, many of the city's factories and homes had only roof lines visible as residents, many evacuated to safety, woke to bright sunshine. Hundreds of onlookers gathered above the river to see the devastation at first light.

The swollen Brisbane River was choked with debris after bursting its banks and engulfing large districts of the city the previous day. Power was cut to many areas in and around the city because of worry the waters could cause electrocutions.

Boats and river pontoons torn adrift by the deluge lay piled on river banks as roiled brown water raced past.

It's crazy, said Brooke Fenton, surveying the filth and floods in the forecourt and basement of her apartment complex.

We're about to go and take a look, she said nervously, clutching two bags of possessions, adding she did not think the water could have reached her second-floor unit.

Inside one of the apartments, armchairs, a kettle and pillows were floating in the water. The doors and windows were open with the water two thirds of the way up the wall after dropping several feet, leaving brown stains on the curtains.

Emma Yabsley, an economics and arts student at the University of Queensland, was not as lucky, losing most of her possessions when her second-storey apartment flooded.

It (the apartment) was full, said Yabsley, adding her sofa was floating in the murky water with flood levels near the roof.

We only got out our bags and documents, she said after being taken by boat to survey the damage.

REBUILD COULD TAKES YEARS

Brisbane Mayor Campbell Newman on Thursday issued a rallying call for volunteers to start cleaning up his flooded city.

Brisbane people today I am calling on you to really help your community. Tomorrow if the water goes down sufficiently, I want clean up crews out there across the city, he said.

Anyone with a bulldozer, front-end loader or dump truck, we want to hear from you. We will send you in when the water goes down to clear local streets, he said.

Newman warned residents that when floodwaters recede the threat of disease would remain as raw sewage has contaminated many flooded homes.

I think the clean up will take many, many weeks and the reconstruction will take one and a half to two years, he said.

South of Brisbane, neighbouring New South Wales state has also been hard hit by flooding, causing widespread evacuations in many small communities, while southeast Victoria state had also been hit by drenching rain, flash flooding and landslides.

One central bank economist has warned the floods could cut the gross domestic product (GDP) measure of national income by as much as 1 percent, a blow that would wipe A$13 billion from the economy and place at risk the government's promise of a return to surplus in 2012-13.

At central Suncorp Stadium, home to the city's beloved Broncos football team, children's swimming floats had been placed on the arms of a bronze statue depicting a past playing hero. Green garbage bags floated nearby.

Power companies said they were planning to bring in large generators to restore power in Brisbane's financial heart as soon as the water cleared over the next few days.

But devastated areas further west, hit by flash flooding on Monday described as an inland tsunami, could be without power for weeks, power provider Energex said.

Further north, in Queensland's coal-mining heartland, one of the nation's biggest export-earning regions showed signs of recovery, with coal-freight operator QR National QRN saying its worst-hit rail network could reopen in a week.

Resources Minister Martin Ferguson Obviously he would make an assessment next week as to potential infrastructure requirements for the disrupted coal industry, as water receded.

Obviously the amount that we are going to export in the foreseeable future could be potentially reduced significantly but there is also, I suppose an unders and overs game with respect to the impact on the spot prices, Ferguson said.

Gdp Storm South Africa Australia