Water from south-east Queensland's largest dam will be released for a two-week period in a bid to prepare the state for the looming wet season.
SEQWater will begin the release of water from Wivenhoe Dam from Saturday.
It is expected 116,000 megalitres of water from the dam will be released with the water storage level to be reduced from 90 per cent to 80 per cent.
Premier Annastacia Palaszczuk said it was an early move to increase flood mitigation capacity at the dam to prepare for the "worst-case scenario" in the upcoming wet season.
"It is being done safely and in a controlled manner and it is being done to ensure we are on the front foot after the crucial BOM [Bureau of Meteorology] advice," she said.
"We've all seen what has been happening with devastating flooding in New South Wales and Victoria.
"Tasmania is about to experience a significant flood event.
"We must be ready for the worst."
Discount on water bills
Ms Palaszczuk said the state government would reduce the cost of water bills for all homes connected to the south-east Queensland water grid to the equivalent of two weeks' worth of free water.
Households will see a $55 discount on their water bills.
"That will apply to approximately 1.38 million homes," she said.
"It allows for the use of 13,200 litres of free water for each of those homes and families.
"That's about double the normal household usage over a fortnight.
"So I encourage families to make the most of this rare opportunity and Gerni the driveway, to wash down the house and to clean out your gutters."
The discount will apply to water bills before December and will be fully rolled out by March.
It will apply to homes in Brisbane, Redlands, Logan, the Gold and Sunshine coasts, Noosa, Ipswich, the Lockyer Valley and the Somerset, Scenic Rim and Moreton Bay regions.
'It wasn't an easy decision'
Water Minister Glenn Butcher has the power to authorise the release of the water.
He said the decision to release water wasn't made lightly.
"I've taken advice and information from meteorologists, scientists, dam engineers, the dam safety regulator and environmental experts as we plan appropriate steps for the wet season ahead," he told parliament.
"The new temporary water supply level [of 80 per cent] balances water security for the region and frees up about 116,000 megalitres of additional flood storage in that compartment which is about 50,000 Olympic-sized swimming pools.
"This decision doesn't alter the flood manual and the control releases will be made in accordance with the manual.
"Last November we were down to 55 per cent and we were looking at going into water restrictions," he said.
"So it's a very careful balance that we have to manage."
Ms Palaszczuk said she was "very confident" with the advice.
Climate drivers La Nina and a negative Indian Ocean Dipole mean Queensland is likely to receive above average rainfall.
The weather bureau is predicting a higher risk of flooding because of already wet ground meaning any rainfall will likely push creeks and rivers higher more quickly.
Wivenhoe Dam was finished in 1984 and designed as water storage dam and for flood mitigation.
The dam can hold about double its drinking capacity in flood water, holding back water in the Brisbane River system.
