Premier Annastacia Palaszczuk says Wivenhoe Dam operators have been authorised to release 116,000 megalitres of water into the river, which flows through inner Brisbane, from Saturday.

She says lowering the dam level from 90 per cent to 80 per cent capacity will ensure it can be effectively used for flood mitigation.

“We’ve all seen what has been happening with devastating flooding in NSW and Victoria. Tasmania is about to experience a significant flood event,” Palaszczuk told parliament on Thursday.

“We must be ready for the worst.

“From Saturday, SeqWater will begin the release of water from Wivenhoe Dam in an early move to prepare for the worst case scenario based on the (Bureau of Meteorology) advice.”

SeqWater also released a statement saying “minor gated releases” from  the dam would begin from mid-morning Saturday “to draw down water within the dam and accommodate additional flood mitigation storage for the 2022-23 summer season”.

The decision follows a report into the February-March floods in which 13 people died and more than 9000 homes and businesses were damaged, finding the dam had been well managed.

It said low-level bridges at Twins Bridges and Savages Crossing may be affected and asked people to check with Somerset Regional Council for local road updates.

Brisbane Lord Mayor Adrian Schrinner has been calling for water to be pre-emptively released from Wivenhoe in recent months but the government dismissed his pleas as being too soon.

Water Minister Glenn Butcher said on Thursday he had authorised the release in response to the BoM’s long range flood forecast.

“This isn’t a decision that I’ve taken lightly,” he said.

“We saw in February that these extreme weather events can be unpredictable and keeping Queensland safe is at the top of my priority list.”

Palaszczuk also announced that 13,200 megalitres of free water, about two week’s worth, would be given to households across southeast Queensland connected to the SEQWater grid.

She said the deal would be worth $55 per household and apply to customers in the Brisbane, Redlands, Logan, Gold Coast, Sunshine Coast, Noosa, Ipswich, Somerset, Scenic Rim, Moreton Bay and the Lockyer Valley councils.

Butcher said the releases would be managed to minimise any impact on the community. If significant wet weather occured while the dam levels were being lowered, Seqwater would adjust its strategy to respond as required.

“We know this will give peace of mind to families in SEQ and so too will the discount to water bills,” he said.

A report into the preparations for and response to the 2022 floods by the Inspector-General of Emergency Management was released on Wednesday.

It found the overloaded State Disaster Coordination Centre failed to issue timely alerts in Brisbane and some properties were inundated without warning.

Some local government staff also didn’t have enough training or knowledge to effectively use the state-run alert system.

Inspector-general Alistair Dawson called for a new process for alert requests requiring “urgent approval and distribution without delay” to be implemented by November.

He also recommended a review of the process, including requesting, composing, authorising and issuing messages by the same date.

A probe of the Queensland Emergency Alert Manual should also be conducted and completed by November next year, the report said.