CSIRO: 10 new detention dams could have reduced 2022 flood levels by 2 metres
A CSIRO report found that building 10 new water detention systems in New South Wales' northern rivers could have reduced flood levels by 2.1 metres during the devastating 2022 floods, but would not have prevented the Lismore CBD levee from overtopping.
The CSIRO released a report on Tuesday, four years after it was commissioned by the Morrison government following the 2022 floods that killed 13 people, left more than 4,000 properties uninhabitable, and caused an estimated $16 billion in damage.
Detailed Findings
Researchers modelled two scenarios: "Bundle 1" with five water detention systems and "Bundle 2" with 10. The latter could have reduced water levels by 2.1 metres during the February 2022 floods, when the flood level in Lismore reached 14.4 metres—the highest on record. However, it would not have prevented the city's CBD levee from overtopping by 3.8 metres.
CSIRO hydrologist Dr. Jai Vaze emphasized that the proposed systems are not traditional dams but temporary water detentions where gates close only when floodwaters exceed a certain level. He noted that implementation would depend on a business case, detailed architectural proposals, and environmental approvals.
Lismore Residents React
Opinions among Lismore residents were divided. Matthew Gooley, owner of a family-run menswear business that lost millions of dollars in stock, said the measures would be costly but "amazing for Lismore." Paul Morgan, owner of Lismore Computer Solutions, expressed support if the systems work. In contrast, Irene Guymer, whose daughter's farm flooded nearly to the second floor, called the spending a "waste of money" and advocated moving the CBD to Goonellabah.
Political Stance
Federal Emergency Management Minister Kristy McBain and her NSW counterpart Janelle Saffin welcomed the report, saying it would inform future flood resilience measures. Saffin, the state MP for Lismore, said the report "gives us real hope."
However, Greens upper house member Sue Higginson, a Lismore local, criticized the report, stating that "billions of dollars in new dams will not prevent severe flooding" and called for nature-based solutions like reforesting the river basin. She proposed transforming the Lismore CBD into a "wetland cultural market hub."
Federal Nationals MP Kevin Hogan, who has called for engineering solutions since 2022, supported the report: "The CSIRO have provided a solution to keep us safe. The state and federal governments must act."
The state and federal governments announced a joint $3 million feasibility study but have not committed to implementing the measures modelled in the report.
