Flood engineers hired by the operators of the Wivenhoe and Somerset dams failed to follow guidelines, which ultimately contributed to the severity of the 2011 Brisbane floods, the NSW Supreme Court ruled last Friday.

Justice Robert Beech-Jones found Seqwater, Sunwater and the State of Queensland “vicariously liable for any breaches of the duty of care owed by the flood engineers that they each employed”.

The class action claimed the three defendants are legally responsible for the actions of the four flood engineers who were in charge of operations at the two dams from January 2-11 in 2011.

Seqwater owned the dams and employed two of the engineers at that time. Sunwater was contracted to provide flood management services to Seqwater and the boss of one of the engineers. The state employed the fourth engineer.

“At the heart of the plaintiff’s case is the contention that during the period…the flood engineers were obliged but failed to evacuate water from the dams in advance of rainfall predicted by rainfall forecasts,” the ruling says.

“The plaintiff contended that the flood engineers comprehensively failed to apply the manual throughout the flood event.

“The identified failings of the flood engineers do not concern decisions they made in the heat of the moment. Instead, they derive from a failure of approach, specifically a failure to follow the very manual that they had drafted or participated in drafting almost 18 months previously.”

A spokesman for Maurice Blackburn Lawyers, which filed the class action in 2014, told insuranceNEWS.com.au “a significant portion of loss in this case is held by insurers”.

Insurers paid out more than $1.5 billion in claims (in today's dollars) following the 2011 floods catastrophe, according to the Insurance Council of Australia (ICA).

“[Insurers] will review [the] decision for its commercial implications,” ICA spokesman Campbell Fuller told insuranceNEWS.com.au.