The engineers operating Brisbane’s Wivenhoe Dam have defended their actions during the devastating 2011 floods despite conflicting evidence in internal records.

The Queensland Floods Commission of Inquiry was reconvened last Thursday to test allegations published in The Australian newspaper in late January.

The newspaper claimed the dam’s logs and previous drafts of the engineers’ report into the flood suggested they had not engaged in flood mitigation strategies until too late, thus causing damage to Brisbane’s suburbs.

The inquiry is being watched closely because massive legal action against Seqwater, the dam’s owner, could be launched by insurance companies and other injured parties if the engineers are found to have mismanaged the dam.

Insurance companies have already paid out more than 58,000 claims worth more than $2 billion over the Queensland floods.

Lawyers Maurice Blackburn has confirmed it is investigating a potential class action over the flooding of Fernvale.

Counsel for the inquiry, Peter Callaghan, has accused the engineers of failing to “consciously” follow the prescribed strategies for running the dam, in breach of their manual.

The engineers – John Tibaldi, Terry Malone, Robert Ayre and John Ruffini – have conceded that their record-keeping was poor, but claim the sequence of water releases in the five days before Brisbane was flooded show they were following the approved strategy.

They say the dam’s water level determines the water release strategy they must follow.

The current issue turns on when the engineers changed their strategy from W1 through to W2 – a transition stage – and W3. The latter two stages release more water from the dam and are designed to prevent dramatic urban flooding.

Yesterday Mr Callaghan put it to Terry Malone that their report did not “record conscious engagement of strategies [during the January 8 and 9 last year]”.

“No that’s not the truth, and I think it’s clearly evidenced by our actions at the time,” Mr Malone replied.

“The priority for W2 and W3 is minimising urban damages, and by our actions all through that period that objective was achieved because we kept the dam as low as possible with the expectation for major inflows the following days.”

Mr Malone said it was considered “too time-consuming” to keep a written contemporaneous record of the water release strategies at the time.

He said if they released more water over the weekend of January 8-9 there would have been more urban flooding.

The inquiry is continuing.