Wild west fears for Wonthaggi desalination plant

AN expansion of the Wonthaggi desalination plant could create a wild west and double the cost of renting a local house according to Watershed Victoria.

With plans to increase the capacity of the Wonthaggi desalination plant from 150 gigalitres to 200 gigalitres Watershed Victoria fears an influx of construction workers could result in the same social problems experienced 15 years ago.

Drug use, prostitution and soaring rents according to Watershed Victoria President Mark Robertson. A planning document released by the State Government has estimated the desalination plant could be expanded to produce a further 50 GL of water each year.

Wonthaggi’s desalination plant is seen as an essential buffer for city reservoirs with the ability to go on standby in heavy rainfall years to provide water when its needed.

Work on the $840 million upgrade could start as early as 2030 and be completed by 2034 as part of a 30-year strategy to bolster the state’s water security.

“It’s a quick fix,” Mr Robertson said.

“I’m unsure whether the power supply would cope.”

The alternative, according to Mr Robertson, is a second desalination plant west of Melbourne. The Wonthaggi desalination plant is capable of providing up to a third of Melbourne’s annual water demand, underpinning Melbourne’s water supply.

Concerned about the social problems that may be caused by a large temporary workforce needed for the desalination plant upgrade, Mr Robertson wants to know if they’re going to consult with the local community or get the same problems as before.

“How many workers will be required and who’s paying for it?” he said.

“Last time rents doubled, and with the extra demand for power from Victoria’s new data centres, where’s the energy going to come from?”

Another concern for Watershed Victoria is the wastewater pumped into the ocean.

“They don’t worry about being next to a marine park and penguin feeding ground.”

Watershed Victoria said recycled water is a much preferable option.

“If it’s done properly, it comes out as water; stormwater can be used.”

According to Mr Robertson, desalination is the most energy-intensive and environmentally questionable option.

“Simply use less,” he suggested.

“We’re using top-quality drinking water to flush toilets.”

Last year, Melbourne’s water consumption rose by 5 per cent and Geelong's by 14 per cent.

Universal adoption of dual flush toilets could save as much water as a desalination plant can produce, according to Mr Robertson.

“Desalination plants just don’t add up; they cost billions of dollars.”

Mr Robertson called for an environmental effects study to look at the impact of the Wonthaggi desalination plant in the Bunurong Marine National Park and the impact on the community from a predicted influx of construction workers.

Watershed Victoria said it wants to be part of the solution, not the problem.

“Highly paid workers create a wild west that is out of control.”

Westernport Water said it had been managing a high-demand summer period from early February, with Candowie Reservoir relying on potential supplementation.

With Candowie Reservoir secure, nearby tourist locations like Venus Bay and Sandy Point saw high demand in January, leading to low private tank levels.  As of mid-February, Westernport Water was operating with stable storage levels despite higher weekly water usage compared to the same period in 2025.