It ended with revelations of a private company's grand plan to transfer water from the Shoalhaven system to the Murray-Darling Basin.

The unsolicited proposal for the Tallowa to Basin Water Transfer Project is a project of infrastructure consultants Evans & Peck and the Tallowa Pipeline Company.

Dated June 2009, it was prepared for the NSW Government "for its consideration".

The proposal is to capture between 200 and 300 gigalitres a year of overspill water at Tallowa Dam and use a 170km pipeline to transfer water to "cities, towns and industries in the Sydney-Canberra Corridor Region and to the Murrumbidgee and Lachlan valleys in the Murray-Darling Basin".

Mr Stoner's comments on 2ST radio indicated a Tallowa Dam proposal may still be an option for the Opposition.

"If any proposal, including the Tallowa proposal, doesn't meet ... criteria it will be off our list," Mr Stoner said.

He later said the Coalition had no plans to raise the height of the dam wall. The Tallowa project was discussed by Cobar Shire Council in December, a council in the National Party's heartland, but Mr Stoner said there was no connection.

"I have never, ever heard of the proposal ... it doesn't sound environmentally responsible," he said.

Greens MP John Kaye said pumping water over the Great Divide had never been a sensible idea.

"This proposal is even more flawed than most of its predecessors," he said.

In 2006, then Premier Morris Iemma ditched Labor's controversial plan to raise Tallowa Dam wall by 7m in the wake of strong community opposition.

Mr Stoner's comments were seized on by Kiama MP Matt Brown, who said he was "amazed" by what the Acting Opposition Leader had to say.

Mr Brown said the Tallowa Dam issue has been finalised "and the Shoalhaven should not have to go through that heartache again".

Potential Liberal candidate Gareth Ward said it was the Labor Party that put the Shoalhaven through the heartache in the first place.

South Coast MP Shelley Hancock said given Mr Stoner's assurance that nothing would be done unless it was viable economically, environmentally and socially, she believed once he was aware of the scientific evidence and met the community he would see that raising the Tallowa Dam wall was environmentally unsustainable and would rule it out.