Water is gushing from a large hole in the at-capacity 440 megalitre Bolzan Quarry Dam near Warwick.

Fears continued Sunday of a major flooding event in southern Queensland after a failed dam began to gush water, threatening nearby properties.

An emergency was declared on Saturday and nearby residents were evacuated when water began flowing from a crack in Bolzan Quarry Dam, about 30km north of Warwick, southwest of Brisbane.

The 440 megalitre private dam at Talgai was at capacity after recent heavy rainfall when a large hole, about 3.5m by 1.5m, was spotted at its base Friday night night. About half a metre of water had been lost by about midday.

On Sunday morning Southern Downs Mayor Tracy Dobie said that while the dam had dropped 25 per cent authorities were worried about 300 megalitres of water that could rush out.

“The assessment done by the dam inspector this morning is that if the flow continues as it is now, that would be just standard low-level flooding through the valley and through Dalrymple Creek,” she said.

“If the dam wall was to give way, then there would be considerable flooding through that valley and down into Dalrymple Creek.

Ms Dobie said they hoped to open residences back to homeowners Sunday afternoon and told all landowners to check their dams.

“Landowners, they do know their properties and I’m sure after this, those who hadn’t already inspected their dams have been inspecting their dams this weekend.”

IMMEDIATE REACTION

Yesterday afternoon engineers said the risk of major flooding had decreased.

“The volume of water coming out of the hole is gradually starting to reduce,” local councillor Cameron Gow told AAP.

In a statement just after 6.30pm on Saturday, Queensland time, police confirmed the emergency declaration was still in place.

“An emergency declaration under the Public Safety Preservation Act (PSPA) remains in place as a dam at Talgai continues to leak,” Queensland Police said.

“Assessments of the dam’s integrity has been conducted throughout the day with no serious breach of the dam wall detected.

“Residences within the declaration area will remain evacuated until the threat eases. Roads also remain closed.

“Police are working with relevant authorities to ensure all precautions to ensure community safety are undertaken.

“Members of the public are urged to remain clear of the declaration area.”

Engineers predicted a cofferdam with a 50 megalitre capacity and a large paddock would contain some overflow should the dam burst, likely sparing nearby properties. However residents from about 12 properties were still waiting to return home this afternoon.

Queensland Police declared an emergency for low-lying areas around the dam when it began to leak last night.

About 5000 text messages and social media posts were to residents in the nearby town of Talgai, urging them to immediately evacuate homes in low-lying areas amid flood fears.

Police doorknocked properties last night telling residents to leave if they hadn’t already done so.

Southern Downs Regional Council said consulting engineers had assessed the site and the concern has been reduced.

“The water is discharging in a controlled rate, therefore the impact is expected to be minimal at this stage,” the council said.

“There is a large paddock below the dam wall in which the water will first impact and this will allow for a broader dispersal should the dam wall fully fail.”

Ms Dobie told The Courier-Mail early on saturday morning that it was initially feared 250 properties were at risk if the dam wall collapsed.

“The wall has not collapsed completely yet, that was the fear through the night,” Ms Dobie said.

“It’s punched a hole through the bottom of the wall and it is gradually increasing in size.

“We don’t know if or when the wall will let go.”

The council alerted residents last night the Bolzan Quarry Dam was set to break, causing “dangerous downstream flooding” between Talgai West Road and Dalrymple Creek Road.

“Residents need to act to protect life, leave now and move to higher ground,” the council said in a statement.

“Those evacuating have been urged to leave immediately and stay with family and friends in a safe area.”

The Courier Mail reports firefighting and SES crews were at the dam to try and patch up the leak after it first overflowed last night.

However the dam burst again, resulting in more crews and senior officers attending the scene to deal with the flow of water.

Parts of the Darling and Southern Downs have experienced recent heavy rainfall.

Update as at 8:00am on Saturday 15 February 2020 pic.twitter.com/NGwF0CFHPF — SDRC (@SouthernDowns) February 14, 2020

Ms Dobie, said she was confident people in the dam’s path would get out in time.

“The land is really flat so the water will just go out over that land and by the time it has got a bit downstream, it will have dissipated,” she told The Toowoomba Chronicle late on Friday night.

“I have confidence in the people who live there. This is their land, they know what happens and they will do the right thing and know where to go.”

EMERGENCY ALERT for Talgai (near Warwick) - Bolzan Quarry Dam failure as at 11.15pm Fri 14 Feb: https://t.co/ryOLWj9b8Q — Qld Fire & Emergency (@QldFES) February 14, 2020

Dalrymple Creek Road, Talgai and Ellinthorp. Police incident - Road closed to all traffic, Both directions. https://t.co/Tr0oJF0z5G — QLDTrafficDDSW (@QLDTrafficDDSW) February 14, 2020

Emergency Alert for Talgai - Dam failure will result in dangerous downstream flooding in low lying areas between Talgai West Road and Dalrymple Creek Road, Talgai. https://t.co/HaWE8OFpi1 — Queensland Police (@QldPolice) February 14, 2020