AUTHORITIES fear Maryborough's protective levee could be breached when a near-record flood peak hits the Queensland city.

The peak has been revised upwards, to just below the 1955 record, the ABC reports.

An extended family including a one-week-old baby and a grandmother was rescued from a Maryborough property today, after their house was flooded.

They were forced to pile into a ute and drive to a paddock on higher ground. The family was rescued by chopper and taken to the Tiaro police station.

Fraser Coast Mayor Gerard O'Connell told the ABC the Mary River is expected to reach 11m, up from an earlier forecast of 9.7 metres.

"I was down inspecting that levee bank only about an hour or so ago and it was doing its job," Mr O'Connell said.

"But if we do get to the 11 metres as predicted by the Bureau of Meteorology that's going to top over that levee bank.

"We are now working with the SES to begin the door-knocking process so we can advise those people."

Some businesses on the banks of the Mary River have already flooded, along with some homes.

Earlier Mr O'Connell told AAP the flood was expected to be worse than in 2011.