Australia’s largest theme park and its management had “a culpable culture” from the board down, the Queensland coroner has found after the deaths of four people on a ride at Dreamworld on the Gold Coast three years ago.

Coroner James McDougall said he reasonably suspected the park’s operator, Ardent Leisure, had committed a workplace offence and referred his findings to the Queensland office of industrial relations to consider a prosecution.

The state has previously decided not to bring charges against Ardent or individuals in relation to the deaths of Cindy Low, who was a New Zealander, Kate Goodchild, her brother Luke Dorsett and his partner Roozi Araghi.

They were on “raft five” of the Thunder River Rapids ride and died when a water pump malfunctioned on 25 October 2016.

Under Queensland law, companies can be fined up to $3m and individuals fined up to $600,000 or jailed for up to five years.

McDougall detailed “irresponsible”, “dangerous” and “inadequate” safety practices at the theme park that contributed to the four deaths. He made scathing comments about Dreamworld’s maintenance and oversight of the ride, which had a history of malfunction and incident.

He said Dreamworld’s safety failures were “systemic”. These included inadequate training for staff, poor emergency and safety procedures, and piecemeal engineering modifications undertaken without risk assessment.

The ride had broken down five times in the previous seven days. McDougall said he found it difficult to believe that safety action was not taken before the fatal accident.

“Such a culpable culture can only exist when leadership from the board down are careless in terms of safety,” McDougall said.

“It is clear from the expert evidence that at the time of the incident the design and construction of the [ride] posed a significant risk to the health and safety of patrons.

“[A fatal accident] was simply a matter of time. [Multiple safety issues] posed a risk and would have been easily identifiable to a competent person, had one ever been commissioned to conduct risk or hazard assessments of the ride.

“Whilst it is accepted there is always an inherent risk to safety, given the nature of an amusement ride, that was not the case with respect to the [Thunder River Rapids]. No risk assessment [was undertaken] in its 30 years of commission.

“Shoddy record keeping was a significant contributor to this incident.”

Earlier, family members of those who died gave emotional statements in the courtroom.

“The thought that Cindy would not experience all that life had in store for her was harder for us than the thought we might not see her again,” Low’s husband, Matthew, told the court.

“Our heart aches daily as we try with varying success to be grateful for the decades we had. She had the heart of a tiger, fierce and protective.”

Kim Dorsett, the mother of Luke and Kate, spoke about her children and Araghi. “The easier part was burying them, the harrowing part is living without them,” she said.

“We exist in a world full of grief and shattered family and friends; three mothers who have lost their children living with broken hearts and souls, and let us not forget those four beautiful children who will now grow up without a mum, and that is what this is really about.”

Goodchild’s 12-year-old daughter and Low’s 10-year-old son survived the accident.

Ardent Leisure issued a statement on Monday afternoon expressing “deepest sympathies” to the families of the victims.

It said safety was the No 1 priority for the new leadership team at the park, which was focused on continuous improvements to “ride safety and reliability, training of ride operators, emergency management procedures, safety management systems and safety governance”.

“These significant changes which we continue to drive at Dreamworld have been acknowledged by the coroner in his report,” the statement said.

The statement said the company “reaffirms its commitment to implement the coroner’s recommendations”, but made no reference to the coroner’s criticism of the park’s practices or the potential for prosecution.