Lismore business leaders are backing a $3 million government feasibility study into engineering works that could reduce flood heights across the Richmond River catchment by more than two metres.

ABC North Coast reports that CSIRO modelling has identified a package of measures, including up to 10 water retention basins and a secondary ocean outlet, that would have cut the peak of the catastrophic February 2022 flood by 2.07 metres. That flood overtopped the Lismore levee at 10.2 metres and reached 14.37 metres in the CBD.

The Lismore Alliance, which represents 6,000 members, says flood risk is now the single biggest brake on economic recovery in the north. “It is the single biggest constraint on the economic future of this region,” said alliance chair Simon Stahl, who also heads the Casino Food Co-op. He said key questions about compensation for landholders who’d be inundated by detention basins had been “lost in the noise” at recent public meetings, and he backed exploring those questions through the feasibility process.

The 2022 floods cost close to $1 billion to recover from, with more than $350 million in damage to council assets alone. Former Summerland Bank chief executive John Williams told the press conference the bank’s repair bill from the disaster hit $4 million, only partly covered by insurance, and the branch can no longer get flood cover at all. A two-metre reduction in flood height would change the insurance calculus, Williams said: “It will still be expensive but it will definitely be worthwhile to encourage investment back into Lismore.”

Ice cream shop owner Felicity Hyde stopped trading for three months and laid off four staff after the 2022 flood. She rebuilt on the assumption the CBD wasn’t going anywhere and wants governments to follow through.

The NSW and federal governments have jointly committed the $3 million to assess technical, environmental, economic and social feasibility of the CSIRO measures. The NSW Reconstruction Authority will coordinate that work.

The National Emergency Management Agency is expected to release inundation maps in early August showing which properties would sit inside the detention basin footprints. Farmers and upper-catchment communities have flagged concerns about pasture loss and road access, questions the feasibility study will need to answer before any construction decision is made.

Frequently asked questions

What engineering works are being studied for Lismore flood mitigation?

CSIRO modelling has identified a package including up to 10 water retention basins and a secondary ocean outlet for the Richmond River. The $3 million feasibility study will assess the technical, environmental, economic and social viability of these measures.

How bad was the 2022 Lismore flood?

The February 2022 flood overtopped the Lismore levee at 10.2 metres and reached 14.37 metres in the CBD. Recovery costs came to close to $1 billion, with more than $350 million in damage to council assets alone.

When will property owners know if their land falls inside a detention basin footprint?

The National Emergency Management Agency is expected to release inundation maps in early August showing which properties would sit inside the proposed detention basin footprints.

Sourced from ABC North Coast, CSIRO, NSW Reconstruction Authority. Original article.