The NSW Government today declared a proposal to raise the Warragamba Dam wall by 14 metres as “critical” to the state, saying it would “future-proof” western Sydney from flood risks despite widespread opposition to the measure, including from the insurance industry.

WaterNSW, on behalf of the state government, is seeking planning approval for the proposal to raise the height of the dam wall to provide downstream flood mitigation. It is one of nine outcomes identified in the government’s Hawkesbury-Nepean Valley Flood Risk Management Strategy.

“First and foremost my number one priority as Premier is protecting NSW communities and we know from the independent flood inquiry that the best way to protect communities downstream is to raise the wall,” Premier Dominic Perrottet said in a statement.

“This declaration reinforces that raising the dam wall is the most effective long-term flood mitigation strategy to help protect residents across the Hawkesbury-Nepean.

“This region has been hit hard by floods and we are committed to progressing this important project to make sure residents have genuine flood protection into the future.”

Declaring the proposal Critical State Significant Infrastructure means Planning Minister Anthony Roberts is of the opinion that it is essential for economic, environmental or social reasons.

However Mr Perrottet says the proposal would still go through a “rigorous” assessment process, including examination by the NSW Environment Protection Authority and the Federal Government.

The Insurance Council of Australia (ICA), which previously backed the recommendation but dropped its support due to concerns the proposed extension would affect surrounding cultural sites, reiterated other mitigation options will provide better protection.

An ICA spokesperson says “further development on the floodplain must be avoided”.

“The significant investment required to raise the Warragamba Dam wall, potentially after a considerable period of further studies and complicated environmental approvals, could be spent immediately on a range of other mitigation measures in the most vulnerable areas of western Sydney,” the spokesperson said.

“The Government’s own report states that the greatest risk is further planned development. We need to learn the lessons – particularly of the past nine months – and not repeat the mistakes of the past.”

Allianz Australia has also responded to the NSW Government’s decision to give the proposal “critical” status.

“As the history of this proposal demonstrates, effective flood mitigation requires sustained and substantial investment over decades,” the insurer says in a statement to insuranceNEWS.com.au.

The insurer says in the context of the proposal that there are temporary measures that could be taken to enable the dam to mitigate flooding in the Hawkesbury flood plain.

It urges the NSW Government to consider temporary amendments to the dam’s operating guidelines to mitigate the risk of uncontrolled spilling of the dam and causing property damage that would not have otherwise occurred.

“There are various alternative approaches that are best developed by experts, but at a high level, Allianz’s proposal would see the water level of the dam reduced to and maintained at, say, 75% capacity on the [Bureau of Meteorology] declaring a La Nina year to give the dam a temporary flood mitigation capability,” the insurer says.

“Once a La Nina period was declared over, the dam would revert to its current operating objective of storing water for the city of Sydney.”