Authorities are now expecting the flood peak at Maryborough to go over the town's levee.
The peak has been revised upwards this morning - to just below the 1955 record.
An extended family including a one-week-old baby and a grandmother was rescued from a Maryborough property this morning.
The family's house was inundated last night and they drove in a ute to a paddock on higher ground.
A rescue helicopter landed and ferried the family to Tiaro police station this morning.
Officials are still trying to work out how many homes and businesses will be affected, but residents in known risk areas are being told to go to higher ground.
Fraser Coast Mayor Gerard O'Connell says the Mary River is expected to reach 11 metres - up from the 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," Councillor 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 doorknocking process so we can advise those people."
© ABC 2013
18:11 EDT Much needed rain has arrived in some parts of Western Australia, filling dams and improving farmers' confidence.