NSW’s deadly one-in-100-years floods could have been slashed by two metres using dams, CSIRO finds

Building 10 new dams in New South Wales’s northern rivers could have reduced flood levels by up to two metres during devastating floods in 2022, but not enough to prevent a key levee overspilling, a report has found. The CSIRO report was released on Tuesday, four years after it was commissioned by the Morrison government following NSW’s one-in-100-years floods. The extensive flooding in the northern rivers between late February and early April 2022 led to the deaths of 13 people. More than 4,000 properties were left uninhabitable and another 10,849 were damaged. The total socioeconomic and structural damage is estimated at $16bn. The report found additional water detention dams would have reduced flooding by 2.1 metres, but would not have prevented the 3.8 metre over-topping of the Lismore CBD levee in February 2022.