SUNWATER created an "inland tsunami" and was "grossly negligent" for the destruction of property and possessions from the floods in the Callide Valley following Cyclone Marcia, according to engineer Ken Pearce.
Mr Pearce has worked with dams and water management since 1973 and said operators should have been standing at their post operating the gates before the water reached its peak.
The cyclone raised the dam's water level to a point where the dam gates were automatically triggered and released 1.8 Olympic-sized swimming pools into the Callide Valley per second.
Mr Pearce said the operators had a duty of care for the people of the Callide Valley.
"They weren't standing by their posts because of the cyclone. That's not good enough," he said.
"If the operators are at risk standing at their post ready to operate the gates, it is a flaw in the design."
In his opinion it was fundamentally neglect on SunWater's behalf for operating the dam in a way where it was unsafe to open the gates manually in a weather event.
Victorian law firm Madden's Lawyers also believes SunWater was negligent and on Wednesday filed a class action lawsuit on behalf of the victims.
Principal lawyer Brendan Pendergast said inquiries led lawyers to conclude the damage caused by the uncontrolled release could have been avoided.
"We know SunWater was aware of the pending weather conditions in the lead-up to February 20 and that the Callide Dam was already close to capacity," he said.
"We'll be convening periodic community meetings in the Biloela and Jambin regions to provide local residents with up to date advice and information."
Jambin resident Glen Livingstone said he wanted to join the class action against SunWater but had not been asked.
"I received a letter from Madden's Lawyers telling me it would wait for the independent report to be released," he said.
The report was scheduled to be released last Friday but has been postponed until June 5.
"The law suit was filed on the day the report was rescheduled so the lawyers must have some good evidence," Mr Livingstone said.
He said he wanted compensation for the equipment he lost.
"Something back would be great. I'd also like a bit of rain at the moment," he said.