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.
The council has long campaigned against the government's plan due to environmental and indigenous heritage concerns.
Wollondilly mayor Robert Khan used his mayoral minute at last night's council meeting to ask the council to take a stand.
He asked that the council not provide Water NSW 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 Water NSW out, a move that the Blue Mountains Council has also done.
Councillor Matt Gould said he was 'really pleased' that the council had taken this stand.
"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."
Councillor Matthew Deeth said the Environmental Impact Statement (EIS) for the project needed to be locked at all over again.
"If this were any other developer coming council, we'd be telling them to go back to the drawing board," he said.
"This is not about increasing Sydney's water supply - it will not increase our water supply by a single drop.
"This is about flood mitigation, and we already know that there are other options out there, like upgrading flood evacuation routes, but the government doesn't want to look at that because it would cost them more money."
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.
Councillors Gould and Deeth reinforced that the council's decision would not stop Water NSW from holding community information sessions in the region.
"Us doing this will not prevent them from holding these sessions. They have the facility at the dam and local schools if they want to use those," Cr Gould said.
"We are just saying that we won't let them use our facilities because we are not on board with their plan."
A Water NSW spokesman told Australian Community Media (ACM) earlier this month that the Environmental Impact Statement (EIS) was still being finalised.
"When finalised, the EIS will be publicly exhibited, and all interested parties and stakeholders will be encouraged to review and provide feedback," he said.
"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 ACM the dam raising was one of the most effective ways to reduce the amount of water in the Hawkesbury-Nepean Valley communities earlier this month.
"Raising the wall has nothing to do with allowing more development in high-risk areas," Mr Ayres said.
"There are over 5000 properties that are already in high-risk locations that need to be provided with improved protections.
"Raising the dam wall also substantially improves the performance of flood evacuation routes and flood resilience across the community. Any suggestion that raising the dam is about allowing more development in areas that are currently prohibited is just plain wrong."