Warragamba Dam flood a risk for Hawkesbury-Nepean residents

Treat the risk of a flood like the risk of a bushfire this summer — that’s the warning to residents in the Hawkesbury-Nepean Valley ahead of a few wet months.

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Treat the risk of a flood like the risk of a bushfire this summer — that’s the warning to residents in the Hawkesbury-Nepean Valley ahead of forecast heavy rain in the coming months.

With Warragamba at almost full ­capacity, Western Sydney Minister Stuart Ayres has warned floods are ­inevitable unless the dam wall is raised to boost storage capacity.

“We can’t stop the floods from happening unless we raise the dam wall higher, and in some cases those floods wouldn’t be prevented anyhow,” he said.

Warragamba Dam on Thursday. Picture: NCA NewsWire/Bianca De Marchi

But a proposal to increase the wall has been further delayed, with an environmental-impact statement now not set to be released for public comment until next year. Previously, it was expected to come back at the end of 2020.

“We’ve made a commitment that we will go through the full transparent process,” Mr Ayres said.

With the major project set to take “multiple years” to build even if it gets the green light, residents in flood-prone areas are being warned to be prepare this summer.

“If it rains and we cannot stop the water flowing … through the dam wall … that will impact low-lying areas,” Mr Ayres said.

The dam is at capacity with water being released before expected rainfall. Picture: Toby Zerna

A proposal to increase the wall has been further delayed.

He downplayed opposition to the project from environmental groups and others who believe it would lead to significant Indigenous sites being flooded.

“We have to … decide what we are prepared to sacrifice,” he said.

“What small amounts of environmental land (are) we prepared to sacrifice for a temporary period of time to protect large-scale populations downstream?”

Water can be released from the dam if needed but this hasn’t been required since September 19.

A WaterNSW spokesman said that the “most extreme” forecast from the Bureau of Meteorology would see 40mm of rainfall in the Warragamba catchment.

“It is possible a minor spill event may occur if the catchment receives 46mm,” the spokesman said.

Premier Gladys Berejiklian said ­raising the dam wall was a “major ­­com­mitment,” and the government needed to ensure it had “considered all ­alternatives”.

“And (the) government’s going through that process now,” she said.