LEGAL action will be launched by Ipswich City Council if Wivenhoe Dam's managers are proven negligent during the 2011 flood.
Ipswich mayor Paul Pisasale said yesterday the council would seek financial compensation for damage caused by floodwater.
The bill for council property alone has been put at $120 million.
The Mayor made the comment after Seqwater engineer John Tibaldi broke down and wept at the flood inquiry during cross examination.
Mr Tibaldi was one of four engineers responsible for water releases in the lead-up to the floods and he wrote Seqwater's final report on the dam's operations.
"This is what I've been saying for months; the flood inquiry should focus on the management of the dam," Cr Pisasale said.
"Seqwater has been trying to justify their actions rather than owning up to what they did.
"All the anguish and suffering over the last 12 months. There will be a massive compensation claim.
"I can see a class action from the city to recoup the massive monetary loss.
"A metre or two less of water would have stopped the pain.
"They have a lot of responsibility but they get big bucks to do their job."
Ipswich City councillor Paul Tully said Seqwater water bosses should be "stripped of their obscene pay bonuses if they are found to have contributed to last year's disastrous flooding".
He said "evidence was emerging the dam release strategy was grossly flawed and there was a cover-up by dam bosses to conceal their negligence".
"If there are any adverse findings by the commission, heads must roll in Seqwater," Cr Tully said.
"Thousands of home and business owners and insurance companies which paid out on the flood are set make billion-dollar claims against the dam operators and the State government.
"If there were major water releases from Wivenhoe in the first 10 days of January, a few rural bridges would have been inundated but Brisbane and Ipswich would have been largely saved."
The inquiry has scheduled nine days of additional hearings to examine allegations dam engineers failed to move fast enough to a higher water-release strategy designed to protect urban areas from inundation.
Counsel assisting the inquiry Peter Callaghan accused Mr Tibaldi of writing the official report to convey the impression it followed the flood manual.
"I would suggest that you and the others (engineers) have shown disregard for the manual during the event," Mr Callaghan said. "In preparing the report you have shown a disregard for the truth."
Mr Tibaldi rejected those claims.
Member for Ipswich Rachel Nolan said her government was "committed to a full, independent, Commission of Inquiry".
"That's why we called it and that's why the Premier has always said it must do everything in its power to get to the truth," Ms Nolan said.
"That truth rightly includes proper consideration of matters including the operation of the dams, councils' development practices (including the approval of subdivisions in the flood zone) and the emergency response."