Push for alliance of councils: Colong Foundation's Give a Dam campaigner Harry Burkitt, Blue Mountains councillor Brent Hoare and mayor Mark Greenhill met at Glenbrook to discuss the Warragamba Dam issue.

The council will urge Hawkesbury, Penrith, Wollondilly, Liverpool, Camden, Lithgow, Oberon and Wingecarribee councils to form an alliance, in a motion put forward by Greens councillor Brent Hoare at Tuesday's council meeting.

It’s proposed to raise the Warragamba Dam wall by 14 metres to reduce flood risk in the Hawkesbury-Nepean Valley. Environmentalists say parts of the Blue Mountains World Heritage Area will be inundated as a consequence.

“Blue Mountains City Council has already made our position against the proposed raising of the Warragamba Dam wall clear," Cr Hoare said.

“We now call on neighbouring councils to join us in taking a united position in opposition to the NSW state government’s unsustainable proposals to offer an illusion of flood protection at the expense of inundation of our wild rivers.

“Nothing will prevent floods from happening, what is needed is more appropriate planning of development in flood zones, and a much greater effort to prepare communities to get out of harm’s way when the big one comes.”

Mayor Mark Greenhill urged the neighbouring councils to join the fight.

“We need the combined voices of as many local governments as possible to stand up and say 'no' to what can only be described as environmental vandalism on a massive scale,” he said.

Liberal councillor Chris Van der Kley supported the motion, and added "let's hope that through this debate we are having that we get some sort of solution out of it to help the residents of the plains."

Liberal Kevin Schreiber said he couldn't support the motion because a number of his family members had died in the Ebenezer floods in the Hawkesbury in the 1800s.

"Without the dam wall there will be more people that will drown on these flats," he said.

Liberal Brendan Christie also voted against.

The Colong Foundation's Give a Dam campaigner Harry Burkitt said raising the dam wall could place the Blue Mountains World Heritage listing in danger.

"Forming an alliance of western Sydney councils who oppose the raising of Warragamba Dam wall is an important step in halting the progress of this environmentally destructive project," he said.

"Whether it be because of floodplain over-development or the destruction of Indigenous cultural sites, we look forward to councils of all political stripes joining Blue Mountains City Council in opposing the raising of Warragamba Dam wall." 

The NSW government is developing an environmental impact statement for the dam plan, to be released this year.