Downstream communities in the dark over Warragamba Dam safety

By Michael Sainsbury

Premier Chris Minns has confirmed Sydney’s main water supply Warragamba Dam may need remediation works due to geotechnical risks that could involve raising the height of the dam wall.

But he reaffirmed that whatever the case his government would not be raising the dam wall by 14m, a project that belonged to the previous government.

Minns’ admission followed a story in The Guardian May 16 that unnamed incoming ministers in the government had been briefed by bureaucrats that safety issues might require work on the giant dam wall.

“Water New South Wales is briefing the Minister of Water Minister about firstly, the 14 metre increase which was proposed by the New South Wales government, which was a flood mitigation measure downstream and had cost of at least $2 billion to $3 billion. This won’t be going out by a Labour government. We’re not committed to it. We will not build it,” Minns told media May 16.

“There are other geotechnical risks associated with the dam wall, which means that water New South Wales and the Board of Water New South Wales may have to take action to remediating the structure from an engineering point of view. I’m not in a position to release that advice right now, but I can confirm we’ve had briefings from engineers at Water NSW about next steps and we’ll have more to say in the coming days.”

Any problems with the dam represents significant uncertainty and potential danger for the Hawkesbury region which has suffered from poor dam and water management during the past three years of the relentless La Nina “ wet” weather cycle.

While the precise details remain unclear, the news comes as a huge shock, as it was never mentioned by the previous government during its 12 years in office.

The Perrottet government announced in 2022 that it would back plans to raise the dam wall by 14 metres claiming that the project would help mitigate flooding in Western Sydney and the Hawkesbury. There was no mention of any remediation in the Environmental Impact Study into the raising of the wall.

But the plan was met with skepticism and opposition on a number of fronts with suspicions that a key reason behind the plan was to enable the approach of even more property development projects on the vast floodplains of western Sydney – as such a boon to the Coalitions “mates”.

“I want to make sure that we’re clear about the government’s commitment not to increase the wall by 14 meters, which we’d see in certain instances and inundation of the National Park. And in particular, indigenous sites and World Heritage protected, natural environment,” Minns said.

Hawkesbury residents would remain isolated for longer and local residents and business will be worse off should the Warragamba Dam be raised, according to findings in the key report into the project.

Major Hawkesbury transport routes and bridges will be closed for longer, access to “health facilities” impacted and lowland residents, businesses and farmlands will remain submerged for more than twice as long should the Warragamba Dam wall be raised, the Warragamba Dam Raising, 2021 Environmental Impact Statement (“The Report”) prepared for the project found.

Despite this, Hawkesbury Council Mayor Sarah McMahon was angered when the wall raising project was scrapped.

“As the mayor of this community, where the Hawkesbury has been under water time and time again, where I have seen homes destroyed, residents without food, complete mental anguish and our local roads and sporting infrastructure smashed, Chris Minns and his ministers just ripped all hope from us in terms of sensible, long term flood mitigation,” she wrote on her Facebook page.

The previous government was also determined to sell Sydney Water which operates the dam to private investors. But that plan was withdrawn during the election campaign after it proved a turn-off for voters tired of privatisation leading to poorer and more expensive services in transport and power.

The latest revelation about the dam represents a headache for the newly elected Labor government that went to the March with a promise to cancel the Coalition government’s plan to raise the wall at least 14 metres. But the Coalition wall raising plan appeared to be so far unfunded.

The Parliamentary Budget Office (PBO) said that dumping the project would save just $3.9m in 2022-23 only with no spending earmarked for subsequent years. But the cost of the wall lifting project was $1.95 billion according to Infrastructure NSW.

It has been noted that this does not include the cost of biodiversity offsets that would be necessary to compensate for a raft of the environmental impacts in the world heritage-listed Blue Mountains region.

The Dam falls under the purview of a range of government ministers led by Water Minister Rose Jackson and Environment Minister Penny Sharpe as well as Planning Minister. It also falls with the remit of Deputy Premier Prue Car who is also Minister for Western Sydney.