Cubbie Station dam collapse details revealed

Documents obtained by Queensland Country Life reveal the dam that failed and flooded more than 100 cotton modules, the M3/4 ring tank, could have released almost 50,000ML of water into surrounding paddocks.

At 6.1m deep, the dam is capable of storing at least 47,130ML, or more than 18 Olympic sized swimming pools - about 10 per cent of the station's 462,500ML storage.

It appears the water breached the 4km northern dam wall, flooding at least four paddocks totalling about 1560ha.

However, it is unclear how full it was at the time.

Dirranbandi, which averages 298mm of rainfall annually, has received uncharacteristically large falls in the past 21 months.

The town received 732mm last year, and had already recorded 553mm from January to August this year.

University of Queensland Professor and dam expert Alexander Scheuermann said dams could be stressed if their parameters were exceeded, which could become more common due to climate change.

"Dams can be stressed to the limit if the conditions for which the dam was designed are exceeded," Prof Scheuermann said.

"I am afraid we have to adjust to the fact that these situations may occur more frequently as a result of the ongoing climate crisis and the increasing number of extreme weather events."

Built in 1999, M3/4 is the fourth biggest storage after Beltana (112,302ML), Urandool (82,440ML), and B2 (79,086ML).

Images from Sentinel-2 satellites, taken every five days, show the dam collapsed around September 9.

They show the dam intact on September 4, losing water on September 9, and fully drained by September 14.

It is gravity fed by overland flow of river and floodplain water, with inflow and outflow controlled by steel gate structures.

Macquarie Asset Management, whose fund owns Cubbie Ag, declined to comment on the incident, as has Balonne Shire Council. Across the district, contacted farmers are not speaking.

Professor Scheuermann said in Queensland, the safety of dams was well regulated by the state government, and the responsibility rested with the dam owner.

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