Authorities in the southwest Queensland town of St George are scrambling to build massive levees to hold out a record flood that's predicted to swamp 80 per cent of the community.
The weather bureau said the Balonne River was predicted to reach a record 14 metres at St George on Saturday, with the possibility of small increases on Monday or Tuesday.
In March last year, St George and its satellite towns experienced what they thought was a once-in-a-century flood, when waters reached 13.39 metres.
But now it's round two.
At 2pm (AEST) on Tuesday the river was just over 12 metres and rising.
The peak, expected on Saturday, is predicted to affect 80 per cent of the town but Balonne Shire Mayor Donna Stewart said a massive levee-building operation was underway to minimise the damage.
"There would be a possibility of 80 per cent of the town having some form of inundation, that would be some with water through houses and some with it through their backyards," Ms Stewart said.
"We've been frantically building levee banks across those entry points and building them up to 14.5m," she said.
"We're extremely concerned."
Vulnerable areas such as Isles and Murchison Streets are being bolstered with levees, and Ms Stewart said if all went to plan, the majority of the town could be saved.
"If we've undertaken all of this leveeing, there is still about 30 houses all up that would get some form of inundation that we just can't protect," she said.
Meanwhile, seven seriously ill patients have been flown out of the St George Hospital and the remaining patients will be discharged before Saturday.
Emergency services have established a temporary field hospital for outpatients and short stay patients on higher ground on the Carnarvon Highway.
Nursing home patients will also be flown to Brisbane on Wednesday morning.
Self-evacuations are underway for the town and the evacuation centre will open on Wednesday.
The city has been isolated.
The small town of Dirranbandi, southwest of St George, is also isolated, and will remain cut off for a month.
"It's totally surrounded by waters," Ms Stewart said.
All homes have been saved by a levee bank that was built around the town's perimeter last February to protect its 540 residents from flood waters.
"They're a very resourceful community; they did it themselves and worked on it day and night," Ms Stewart said.
