Wollondilly Council will not allow the state government to use its facilities for community information sessions on the proposal to raise the Warragamba Dam wall.
It follows a decision by Blue Mountains Council to block their use of facilities to WaterNSW.
Both councils have long campaigned against the government's plan due to environmental and Indigenous heritage concerns.
Wollondilly mayor Robert Khan used his mayoral minute at Tuesday night's council meeting to ask the council to take a stand. He asked that the council not provide WaterNSW access to council facilities for community engagement purposes 'due to the nature of the project'.
"Wollondilly Shire Council joined forces with Blue Mountains Council to oppose the raising of the Warragamba Dam Wall, to protect valuable Indigenous sites, as well as the natural environment, plant and animal species that will be impacted by the proposed wall raising," Cr Khan said.
"I do not believe that council should be enabling engagement when in the view of the council the fundamental premise of the project and the analysis underpinning its conclusions are incorrect."
This is not about increasing Sydney's water supply - it will not increase our water supply by a single drop.Matthew Deeth, Wollondilly councillor
Cr Khan also stated that the state government had access to its own facilities, including school halls and the Warragamba Dam visitor's centre, that could be used for this purpose.
Councillors unanimously voted in favour of the plan to lock WaterNSW out, a move that the Blue Mountains Council made at their meeting on June 29.
Cr Matt Gould said "all councillors are in lock-step on this issue. It is something that we are all really passionate about," he said.
"Every single part of the process to date has been undercooked, from the Aboriginal heritage study that was done over just 25 days and only looked at 27 per cent of the area affected, to an environmental assessment that was so bad the government had to have the law changed to weaken the environmental protections the project was assessed against, to the lip service that has been given to genuine consultation on the significant impacts the project will have on Wollondilly communities."
Cr Gould said it 'blew his mind' that the Indigenous heritage report only took 25 days to complete.
"I have spent a lot of time in that valley and it is full of incredibly rough terrain," he said. "They only looked at a quarter of the area and they found hundreds of sites - imagine what they have missed."
The state government has proposed raising the dam wall to mitigate the risk of flooding in the Hawkesbury Valley region.
However, Indigenous residents, scientists, environmental action groups, local councils, politicians and the United Nations Educational, Scientific and Cultural Organization (UNESCO) have raised various concerns about the plan.
A WaterNSW spokesman told The Blue Mountains Gazette earlier this month that the Environmental Impact Statement (EIS) was still being finalised.
"Dates and locations for the public exhibition of the EIS and community information sessions will take location, capacity, accessibility and ability to comply with COVID-19 safety into account and will not be finalised until dates for exhibition have been confirmed.
"Importantly, the final decision on the proposal to raise the dam wall for flood mitigation will only be made after all environmental, cultural, financial and planning assessments are complete."
Western Sydney Minister Stuart Ayres told the Gazette the dam raising was one of the most effective ways to reduce the amount of water in the Hawkesbury-Nepean Valley communities.
- with B.C Lewis