Excessive silt and mud washed up on a flooded road creating a hazard that authorities did not recognise, finds a coroner investigating the deaths of a mother and two of her children whose van skidded off a road into a river in northern New South Wales.

Key points: Acting State Coroner Teresa O'Sullivan recommended Tweed Council identify roads likely to create hazards during floods

Acting State Coroner Teresa O'Sullivan recommended Tweed Council identify roads likely to create hazards during floods She also asked the Council to actively let road users know about mud and silt on roads after floods

She also asked the Council to actively let road users know about mud and silt on roads after floods It was recommended that even if water was not on a road, it could be closed until the hazard was removed

Acting State Coroner Teresa O'Sullivan handed down her findings into the deaths of 43-year-old Stephanie King and two of her children, 11-year-old Ella-Jane and seven-year-old Jacob, who died after their van went off a muddy Dulguigan Road into the swollen Tweed River at Tumbulgum on the state's far north coast in April 2017, just days after a major flood hit the region.

The coroner made five recommendations to the road owner, Tweed Shire Council, which was responsible for Dulguigan Road, where the accident occurred.

The coroner praised the bravery of daughter Chloe who managed to escape the sinking vehicle and also the courage shown by Stephanie King's partner, Matthew Kabealo, since the tragedy.

Ms O'Sullivan said although Dulguigan Road was prone to flooding, the extent of silt and mud washed up was far greater after this flood than had been experienced previously and the council was not aware it caused such a significant road hazard.

The coroner said it appeared "that the council was so overwhelmed by the flood … that it did not have the resources to effect road closures in accordance with the procedure in place at the time."

She said she was satisfied the council had made a significant effort to address shortcoming with staffing levels … and had erected a guard rail to prevent a similar fatality at the same time.

She also acknowledged Tweed Shire Council's construction of a 220-metre safety barrier guard rail along Dulguigan Road, near the site of the accident.

Coroner's recommendations Council consider a study on roads within the Tweed Shire to identify particular hazards during floods and strategies to mitigate such hazards

Council consider a study on roads within the Tweed Shire to identify particular hazards during floods and strategies to mitigate such hazards Consideration to updating standard operating procedures to provide for works officers to actively let road users know about mud and silt after floods

Consideration to updating standard operating procedures to provide for works officers to actively let road users know about mud and silt after floods To increase the number of volunteers involved in the council-run flood/road spotters program, including criteria to identify mud and silt on roads

To increase the number of volunteers involved in the council-run flood/road spotters program, including criteria to identify mud and silt on roads Consider installing warning signs on the southern and and northern ends of Dulguigan Road for hazards of mud and silt following floods

Consider installing warning signs on the southern and and northern ends of Dulguigan Road for hazards of mud and silt following floods Council considers how best to advertise to community a change of procedure in road closures … even if water is not on a road … a road can also be closed if there is an obvious hazard … until the hazard is removed

Roadside memorial on Dulguigan Rd for Stephanie King, Ella-Jane and Jacob. ( ABC North Coast: Bronwyn Herbert )

Mother's heroic last act

Byron Bay Court heard Ms King sacrificed her own life to save then nine-year-old Chloe, before drowning with her two other children.

Counsel assisting the Crown, Dr Peggy Dwyer, said Ms King had unbuckled Ella-Jane's seatbelt and had tried to do the same for Jacob before she drowned.

"It is abundantly clear on the evidence that Stephanie had no thought for her own life and only tried to save her children," Dr Dwyer said.

Four people jumped into the fast-flowing river and dived into the murky brown water attempting to find the trio, the court heard.

"Those people kept trying until members of the ambulance and police arrived," Dr Dwyer said.

The court heard Ms King had been that morning helping with the clean up at the flood-damaged Dungay Public School and was driving back to their home at Bilambil Heights.

Mr Kabealo told the police that his wife was a cautious driver who would never put her children at risk.

"Safety is paramount, she enjoyed driving and it would not have bothered her one bit to backtrack," he told the police in a written statement.

Muddy road 'like tar'

Police divers search for the van after it disappeared in the flooded Tweed River in Tumbulgum. ( ABC News )

The court heard Dulguigan Road, Tumbulgum, where Ms King and her children were driving had remained open despite significant risks.

The slippery conditions of the road was discussed at length during the inquest, with multiple witnesses describing the hazardous conditions from the thick mud, silt and debris left after the biggest flood in 60 years.

Witness Jill Liibus recalled losing control of her vehicle in mud on Dulguigan Road and her vehicle ricocheting across the road, shortly before Ms King's accident.

Senior Constable Gerry Kemp said when he arrived at the crash site the following day the road was still extremely slippery. "I almost fell over myself when I first got there," he said.

Tweed Heads resident Suzette Wheatley was also helping the flood recovery effort in Tumbulgum on that day, basing herself on the other side of the river and handing out bottles of water.

Ms Wheatley was in her car when she saw the white van go into the river.

The court heard Ms Wheatley called Triple Zero before driving over to Dulguigan Road to offer help.

Ms Wheatley told the court the road conditions were like nothing she had seen before.

"It wasn't like normal mud. It was almost like tar."

Council short-staffed and under-resourced to deal with natural disaster

A photo, tendered as evidence during the inquest, shows flooding on Dulguigan Road the day before the tragedy. ( Supplied )

As owners of Dulguigan Rd, Tweed Shire Council's manager of roads and stormwater, Danny Rose, told the court he was responsible during the flooding event to update the council website on certain local road closures.

Mr Rose said he relied on information from his field officers, SES and police and also online websites such as Live Traffic and My Roads, which alert people to road closures.

He told the court that because of the scale of the flooding disaster, various communities were isolated and roads were completely impassable. He told the court that they had logged more than 380 land slips that had blocked roads, 47 trees on roadways, and 14 bridges were damaged, including one completely destroyed.

"The priority was trying to remove obstructions to the roadways to get in and out… they were the sort of things council staff and contract were trying to prioritise above addressing silt on the road," Mr Rose said.

Counsel assisting Tweed Shire Council, Jason Downing, said in his closing address that the council simply wasn't aware of the significant hazard from silt and mud left after the flood.

"Council did not have the time and resources to attend to Dulguigan Road and conduct its own assessment as to the degree of risk posed."

Tweed Shire Council completed the installation of 220 metres of guard rail along Dulguigan Road, near the site of the fatal accident, in October 2018.

Flood spotters

Counsel Assisting the Crown, Dr Dwyer, asked Mr Rose whether the council-run program known as "flood spotters" was in effect during the time of the floods.

Mr Rose said while the program was active, it did have outdated information and no-one from the council had called people on the list to check on floodwaters.

He also added that the council did not receive any calls from anyone listed on the program, especially near Dulguigan Road.

"It would have been great if we'd got calls from those people," Mr Rose said.

In a statement released after the coroner's recommendations, Tweed Shire Council general manager Troy Green extended his deepest sympathies to the King and Kabealo families and their friends.

He said the tragedy, and the wider impact of the flood, continued to deeply affect the Tweed community more than two years on.

Mr Green said the council fully accepted the coroner's recommendations and was committed to implementing them to prevent a similar tragedy.

"As was acknowledged during the inquest, we have already taken significant steps to improve safety and to communicate more proactively with the community," he said.

These steps include launching a new online emergency dashboard bringing together information from a number of agencies into one place for the community.

Father promises new life with daughter

Matthew Kabealo leaves court. ( ABC North Coast: Bronwyn Herbert )

Mr Kabealo referred to his wife as his hero, best friend and the life of the party.

He described his daughter Ella as an academic and "an absolute joy for Steph and I."

"My only son Jacob who we didn't have for long, but he completed our family perfectly."

Mr Kabealo also recalled one of the last conversations he had with his son, about his first "little girlfriend".

"All memories we will cherish forever, but forever will only be memories.

"I would like to apologise to my daughter Chloe for letting her grow up too quickly.

"I can never give her the nurturing like her mother could. Her mother's love.

"While I can strive to be the best … she will never have an older sister to confide in, or a brother's protection as she matures.

"Our home life has changed but together we will make a new life.

"I miss you so much my beautiful family.

"I will never get over this but will try my hardest to get on with it for the sake of my beautiful daughter."