The floods that swept across Queensland state in late 2010 and early 2011 killed 35 people, damaged or destroyed 30,000 homes and businesses and left Brisbane, Australia's third-largest city, under water for days.

The Queensland Floods Commission of Inquiry was formed to investigate the way officials dealt with the crisis.

Much of the criticism following the disaster fell on the actions of Seqwater, the state government-run water authority in charge of operating the Wivenhoe Dam, which controls the release of water from the Brisbane River.

Critics questioned whether Seqwater's engineers improperly managed the flow of water from the dam, thereby worsening the inundation of Brisbane and the nearby city of Ipswich.

The investigation found that Seqwater did indeed breach the protocols listed in the dam's operating manual, and used the wrong water release strategy in the lead-up to the flooding in Brisbane.

But Queensland Supreme Court of Appeal Judge Catherine Holmes, the inquiry's commissioner, acknowledged that the manual itself was "ambiguous, unclear and difficult to use, and was not based on the best, most current research and information."

The commission could not say whether the dam operator's actions made the flooding worse, though Holmes wrote in the 700-page report that had Seqwater followed protocols, "the possibility exists of at least some improvement in the flooding outcome for Brisbane and Ipswich."

The commission also recommended the state crime commission investigate three Seqwater engineers in charge of determining the water release strategy for the dam. The report questioned whether the engineers were truthful in their testimony to the commission about their actions during the disaster.

Seqwater officials did not immediately respond to a request for comment.

The finding opens up the possibility of a class action lawsuit against Seqwater, but Queensland Premier Anna Bligh cautioned against a rush to judge the water authority.

"This does open the potential for legal action against Seqwater, but it does not of itself establish liability," Bligh told reporters in Brisbane.

The commission made 177 recommendations, including revisions to the dam operating manual, improved floodplain management plans and better public access to flood information. Bligh said the government would adopt all the recommendations.

Overall, however, the inquiry found that the government response to the disaster was good.

"As to how the floods were managed, there is no doubt that they took a state more accustomed to drought by surprise," the commission's report said.

"Generally, though, Queenslanders can be relieved that governments at all levels were able to provide a prompt, if not perfect, response, which compares favourably with the apparent paralysis of government agencies and breakdown in order apparent on the Gulf coast after Hurricane Katrina struck New Orleans."