'Wall of water' struck rural NSW town, killing two people, hours before BOM warnings

While panicked people stood on roof tops to escape a "wall of water" flooding a rural town, the weather bureau warned the disaster would occur many hours later, an inquest has been told.

An enormous flash flood that smashed Eugowra, in central western NSW, on the morning of November 14, 2022, killed 60-year-old Diane Smith and 85-year-old Ljubisa "Les" Vugec.

An inquest is examining the circumstances of their deaths, along with the lead-up to the disaster, the efficacy of weather warnings and the emergency response.

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Local water catchments were already brimming when "constant and intense" rain fell over the region for six hours the evening before the flood, according to a 2023 NSW government report read to the inquest.

It was, at the time, the wettest November day in NSW since 1900.

Mandagery Creek, which flows through the centre of Eugowra, peaked at 11.02 metres just after 9am on November 14.

The level was more than 10 times its ordinary height and one metre higher than the previous flood record in April 1950.

Counsel assisting Sophie Callan SC on Monday told the inquest that water gauges upstream from Eugowra were not transmitting data in the hours leading up to the flood.

Damage to gauges and telecommunications outages resulted in data gaps of several hours, including between 7am and 10am, Callan said.

"During the peak of the flood ... there were no gauges transmitting any information to enable emergency services to predict just how swiftly the water was coming into Eugowra," Ms Callan said during her opening address at Orange courthouse.

Just after 9am, "a wall of water or a wave" struck the village with enough force to knock houses off their stumps and wipe out telecommunications infrastructure, she said.

Several people climbed onto the roof of the two-storey Central Hotel to escape the torrent.

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Around the same time, at 9.07am, the Bureau of Meteorology issued a warning that the Mandagery Creek "may reach" 10.5 metres that afternoon.

"That was not in accordance with what was happening on the ground at the time," Ms Callan said.

The inquest was told Smith, a life-long Eugowra resident and doctor's receptionist, was seen clinging to a tree in raging waters, while Vugec was last seen in his backyard.

The disaster destroyed or damaged 80 per cent of homes and forced the evacuation of 700 Eugowra residents.

Before the inquest opening, Cabonne Shire mayor Kevin Beatty said the loss of Smith and Vugec continued to hang heavily over the small town.

"It's massive. To lose them under those circumstances is horrific," Mr Beatty told AAP.

"They went missing for a while in the floodwaters - that's indescribable."

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Beatty said the inquest was likely to re-open painful emotional wounds, but hoped it would provide answers for those seeking them.

"They're going OK, but it's been slow," he said.

"I don't want to use the word resilient. They're tough."

The inquest is set down for five days before Deputy State Coroner David O'Neil.