Rob Ayre, from dam operator SunWater, is one of four flood operations engineers in Queensland who have the final say on when or whether dam water releases are made.
Today he told the public hearing engineers have never had a training exercise addressing a W4 situation - the scenario where water levels become so high that the main priority becomes releasing water to protect a dam from collapsing.
Mr Ayre was asked why there was a two-day delay in activating the top flood alert for Wivenhoe Dam in early January.
He told the hearing there is a high risk of moving to that top level because releases could needlessly inundate properties.
"We don't want to cause property damage, and if we can avoid it, we will," he said.
Mr Ayre also told the inquiry there was a lack of forethought into how staff at the Flood Operations Centre would be accommodated during the summer disaster.
The inquiry heard workers had to sleep on temporary beds in the office while managing the flood.
BOM boss evidence
Earlier today the inquiry heard evidence from Queensland's regional director of the Bureau of Meteorology, Jim Davidson, in a written submission.
Mr Davidson has responsibility for presenting forecasts and warnings to the Queensland Cabinet, local governments, dam operators and emergency authorities.
In his written submission he said the last wet season exceeded all previous records in many parts of the state.
He referred to a public warning he issued on October 4 to all Queenslanders.
"Prepare early not only for cyclones but also for floods, as we have already experienced record September rainfalls across the state," the warning said.
"Preparation is the key to safety and we encourage communities to factor in the possibility of a destructive cyclone or major flood into their pre-season planning."
Mr Davidson particularly defends the bureau's warnings on January 10, the day a deadly wall of water tore through Toowoomba and the Lockyer Valley towns of Murphy's Creek and Grantham, killing more than 20 people.
The wall of water hit the Lockyer Valley towns between 2:30pm and 3:00pm.
Mr Davidson says the bureau put out a severe weather warning at 11:05am predicting heavy rain and localised flash flooding in the area and alerted the State Coordination Centre at 1:00pm.