The danger of millions of litres of water rushing out of Wivenhoe Dam in an uncontrolled release has passed, Queensland Premier Anna Bligh says.



Authorities have been carrying out controlled releases of water from the dam, which is well above its 100 per cent full mark.



Ms Bligh said there had been concerns in recent weeks that the release would get out of the control of authorities.



She said the dam was designed so that authorities could open the gates in a controlled way and let out a prescribed amount.



"At a certain point the dam exceeds a certain bulk the dam will operate those gates itself," the premier told reporters on Friday.



"And so it becomes what's known as an uncontrolled release.



"We came very close to an uncontrolled release but it didn't actually get there."



She said the prospect had been worrying.



"You'd much rather be in control of a dam that the dam being in control of itself," she said.



The premier has already flagged a review of Wivenhoe Dam after the flooding.



"The dam has never experienced the pressure that it was under this week so this is the first time for a dam that is nearly 40 years old," she said.



"... We want to see how it functioned and again, whether there's any lessons."



But she's already said an expansion of the dam would not necessarily ensure the southeast would avoid future flooding.



"I think we need to be realistic about whether any dam could hold back all of two-and-a-half-million litres of water," she said on Wednesday.



AAP