Representatives from the Victorian Water Forum, anti desalination groups and Plug the Pipe waved placards outside the luncheon and used question time to vent their anger at Government plans to build a desalination plant and the 70-km north south pipe to carry water from the northern irrigation districts to Melbourne.

Plug the Pipe spokeswoman Jan Beer accused Mr Holding of double standards in refusing to dam the heritage-listed Mitchell River in part because of the environmental impact, while pushing ahead to extract water from the similarly heritage listed Goulburn and pipe it to Melbourne.

Mr Holding said desalination represented the only guaranteed means of securing new water for Melbourne as alternatives such as building a dam on the Mitchell, installing rainwater tanks across Melbourne and piping water from Tasmania were either rainfall reliant, environmentally destructive, too expensive, or in the case of the Tasmanian pipe not secure.

“Where it fundamentally falls down is that the Tasmanian Government would not guarantee us access in perpetuity,” he said. “It is on record as saying its highest priority is securing water for its own residents.”

Mr Holding said in the context of less rainfall and growing population dams were not a strategy that would sustain the city into the future.

“We want to move away from an almost total reliance on surface water collected in dams and reservoirs,” he said