A couple who had to be airlifted to safety after their Somerset home was inundated with floodwaters is among the residents who have blamed their local council for worsening the region's flooding.
The Somerset region was one of several areas across south-east Queensland that was hit with devastating floods in February this year.
In one case, a 600-millimetre-wide pipe was the only waterway for a swollen Lockyer Creek to pass through Clarendon Road at Clarendon, west of Brisbane, for about 17 hours.
Local resident Gary Duffy said a bridge should have been constructed by the Somerset Regional Council to ensure water flowed through.
"Previously, the council had built a dam across the natural watercourse and that blocked up the natural watercourse," Mr Duffy said.
"So the water was running down Lockyer Creek that way, and back up through our property almost as fast as it was running down the creek.
"If the dam wasn't built, the water would have been able to flow through to the other side.
"We copped the brunt of it and lost almost everything we had."
'Psychological and environmental damage'
Locals caught in the disaster, including Mr Duffy and his wife, had to be airlifted to safety.
"It's pretty devastating, it knocks you about," he said.
Mr Duffy contacted the council to alert it to residents' concerns.
"They sent their planning engineer out and he said, 'So which way does the creek run here?'
"So, we have the planning engineer on the council, who doesn't even know which way the creek runs, how can you have confidence in their ability to make a decision on that?
"We've had really no contact from the council at all since then, it's as if they don't want to know us.
"It's really simple to fix it if they just do the right thing. Come put a breach there and let the natural watercourse be open."
Clarendon resident Glenn Jackwitz said he had no faith in the Somerset Regional Council after the ordeal.
"We wouldn't have got airlifted out if that causeway was there, and allowed the water to flow through," Mr Jackwitz said.
"It's a naturally designed gully. It's Mother Nature.
"Now that they've changed things, they're creating not only psychological harm but environmental damage as well, and people have to pick up the pieces."
Culverts too small for volume of water
Somerset Regional Council chief executive officer Andrew Johnson said the council was working to respond to the issues raised by Clarendon residents.
"This area is adjacent to the Lockyer Creek, which is historically known to flood in significant rainfall events, such as the February 2022 floods," Mr Johnson said.
"Council has not built a dam at this location and does not build dams. A long-term road culvert [or pipe] is located there.
"Council has dozens of similar road culverts throughout our extensive road network."
Mr Johnson said the council has requested a hydrologic assessment be undertaken at this site to understand the impacts of flooding.
But Mr Jackwitz said the existing infrastructure was not up to the task.
"The culverts that were there were washed out twice and the culverts that they put in each time were never big enough to take the volume of water going through," he said.
"So therefore, there has never been a hydrology study done with the volume of water going through there, otherwise it would have been built to spec [specification]."
Engineer report highlights complexities
Mr Duffy contracted Gold Coast-based J.C Engineers to evaluate the waterway.
Company director Brendan Nielsen noted the flood event was an outlier that was incredibly difficult to be protected from.
"The client had approached us with a few conditions that he found may have contributed to that, a few of those being blockages of that particular waterway infrastructure," he said.
"We did a pre- and post-flood assessment and compared results. The results were not really conclusive in a primary cause, but it definitely contributed.
"In a one-in-100-year flood event, there's a significant amount of water going through, and improvements of creek waterways and infrastructure wasn't really going to be a primary cause to that flooding, when it was going to be flooded anyway."
Mr Nielsen noted a larger space to allow water to flow through would be a benefit in most cases.
"If you're going to have a wider creek way or wider cross section for water to traverse then naturally speaking, the depth is going to be less, so I think that's in any case, not just in that particular property."
Residents build their own flood levee
With a third consecutive La Niña underway, which will increase the chance of wet weather and flooding, Mr Duffy is not leaving the safety of his property to the council.
"We've been working night and day," he said.
"Our neighbours are building a levee wall down their property. We're building concrete walls, and for hundreds of years here, families have never had to do any of that.
"Our whole life is focused on just trying to protect what we have.
"We haven't been able to move on with life until we get the security and knowing that we're going to be at least fairly safe here."
