The engineers who operated two major dams at the height of Queensland's flood disaster were negligent, breached their duties and failed to follow a manual they drafted themselves, a NSW judge has found.
Supreme Court Justice Robert Beech-Jones has delivered a scathing assessment of the engineers' actions at the height of floods that swamped 23,000 properties in Brisbane and Ipswich in January 2011.
In allowing a landmark class action, by 6800 flood victims, he found they were failed by four engineers who negligently operated Wivenhoe and Somerset dams.
The dams were built to help protect residents from the risk of floods.
But Justice Beech-Jones found they simply weren't operated according to the rules, exacerbating downstream flooding when a deluge of "biblical" proportions fell after days of earlier rain.
He accepted that not enough water was released from the dams before it was all too late.
The actions taken by John Tibaldi, Terry Malone, Robert Ayre and John Ruffini "bore little resemblance" to the manual's suggested courses of action, even though they'd helped draft it.
They were "deeply involved" in a dramatic revision of the manual that wrote in a requirement to consider rainfall forecasts in their decision making.
Instead the engineers relied on water that was already on the ground when planning dam releases, because they considered the forecasts to be too uncertain.
"The manual unambiguously and stubbornly required that best forecast rainfall be used to make predictions for the purpose of determining the anticipated storage levels in the dams in order to select the applicable flood strategy," Justice Beech-Jones said in his judgement.
"There are 12 references to rainfall forecasts in the manual. Contrary to a suggestion of one witness, their inclusion ... was certainly not a mistake."
The class action was brought against the state government, Seqwater and Sunwater, who were the employers of the four engineers.
Seqwater employed two of the four, John Tibaldi and Terry Malone.
Mr Tibaldi was Seqwater principal engineer and Mr Malone was senior hydrologist at the time of the floods. Their LinkedIn profiles indicate the men still hold those positions.
Seqwater declined to confirm if the men were still employees working in the area of dam management.
The third engineer was Robert Ayre, employed by Sunwater, which was contracted to provide flood management services to Seqwater. Sunwater declined to comment to AAP.
The fourth was John Ruffini, employed by the state government and the only one of the four who did not give evidence at the class action hearings.