The Queensland Government approved mass release of water from Wivenhoe Dam will begin today, despite state bureaucrats warning that the move could put Brisbane's water security in jeopardy.
Advice given to Natural Resources Minister Rachel Nolan at the weekend cautioned falling dam levels may force the need for "manufactured water" in coming years, including desalinated or recycled water.
Full desalination production could be triggered up to three times over the next five years if drought-like conditions were to occur after this summer's wet season.
Alternative water sources might also need to be developed "years earlier than expected", which could force southeast Queensland water prices even higher.
The advice comes as Brisbane is encountering its driest November on record, with little prospect of rain until next month and local catchments rapidly drying. But about five months' worth of drinking water will be dumped after Ms Nolan on Sunday approved the flood-proofing release of water amid forecasts of another wet summer.
The Queensland Government clearly has to walk a fine line between flooding distaster and droubt.
"I feel confident on the basis of expert advice that the judgment we've made is the right call," Ms Nolan told The Courier-Mail yesterday.
Before making her decision, Ms Nolan asked agencies including dam managers to consider how lowering Wivenhoe would affect water security but added a "precautionary approach" was needed, which effectively elevates flood mitigation above water security.
Seqwater later recommended the Minister lower the dam to 75 per cent but CEO Peter Borrows also cautioned that the decision only took potential flooding into account.
He wrote:"Obviously, we are not addressing the water supply security and pricing issues,".
A Government spokeswoman yesterday said Seqwater was not responsible for water security and insisted dropping dam levels would not leave Queenslanders short of water.
Desalinated water would be needed if the combined levels of Grid 12, which includes Wivenhoe, Somerset and North Pine dams, fell below 60 per cent.
Ms Nolan said there was only a one in 25 chance that levels would hit 60 per cent in the next five years.
"So I don't think there should be anything but confidence in our water security," she said.
A DERM spokeswoman said that, even under severe drought conditions, it would be mid-2017 before levels dropped below 40 per cent, a red-flag level for water security that would prompt recycled water production.