ONE year’s worth of south-east Queensland’s drinking water supply will be released from Wivenhoe Dam to avoid further flooding, although weather forecasters say the worst of the wet season is over.
About 290,000 megalitres of water will be released from the dam later this week to mitigate flooding, Natural Resources Minister Stephen Robertson announced yesterday.
Bureau of Meteorology forecaster Ben Annells this morning said the La Nina system responsible for monsoonal rains in the state had peaked.
He said there was a 50 per cent chance of the south-east corner receiving above average rainfall for the rest of the summer.
‘‘The monsoon tends to come in bursts; it looks as though it has peaked,’’ Mr Annells said.
‘‘We do have another one and a half months where the average rainfalls are still quite high, but traditionally we do not get as much rainfall from April.’’
Wivenhoe Dam overflows during January's flood. Photo: Dean Saffron
He said the chance of heavy rain dropped gradually after January.
The average rainfall for Brisbane in February is 158 millimetres, with 48 millimetres falling in the past fortnight.
In March, the average rainfall is 141 millimetres, compared to an average of 92.5 millimetres in April.
Brisbane received nearly double its average rainfall last month, with 315.8 millimetres falling over the city.
The Sunshine Coast received 558 millimetres of rain, compared to the monthly average of 141.7 millimetres.
Stephen Robertson told ABC Radio this morning the decision to release 25 per cent of southeast Queensland’s drinking water supply was made with an ‘‘abundance of caution’’.
‘‘The ongoing advice from the Bureau of Meteorology is that we are still in a strong La Nina weather pattern,’’ he said.
‘‘It’s based on that advice that we have taken a very precautionary approach.’’
The dam’s role in last month’s flooding of Brisbane remains controversial, with some critics claiming that earlier releases of water would have stopped the inundation of up to 20,000 properties.
Ipswich Mayor Paul Pisasale said some people may be concerned the equivalent of one year’s drinking supply will be released from the dam.
"I’d rather deal with people complaining about their lawns dying, than see more homes and properties destroyed by floods," he said.
"More people would be nervous if it’s still raining and Wivenhoe is still full.
"I’m pleased they’re releasing water ... let’s be on the safe side and have Wivenhoe Dam used for flood mitigation."
Low-lying roads near Ipswich, such as Colleges Crossing, Savages Crossing and Twin Bridges, were likely to be closed during the release.
Ipswich councillor Paul Tully said it was possible the Moggill Ferry would again have to suspend services as debris rushed down the Brisbane River.
"I’d say there will be a lot of speculation, a lot of concern and apprehension," he said.
"People will be talking. People who use Colleges Crossing will probably be angry.
"The dam release also might bring back some fears that maybe something more in terms of rainfall is being predicted."
Mr Robertson said the Brisbane River would not break its banks as a result of the planned releases.
"There will be no significant downstream impacts," he said.
Seqwater chief executive Peter Borrows said it was too difficult to say whether a 25 per cent release would stop another flood on the scale of those seen in January - but guessed it was "extremely unlikely".
"It would have had to have been a major reduction in the storage to have any impact on a major flood event," he said.
Mr Borrows stood by the management of the dam, saying it went by the book in the face of unprecedented flooding.
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