The proposal to raise the Warragamba Dam wall will be discussed at the annual meeting of the World Heritage Committee in Bahrain later this month.
Former Blue Mountains MP and Environment Minister Bob Debus, and Harry Burkitt from the Colong Foundation for Wilderness will travel to Bahrain in the hope the governing body for world heritage will stop the proposal.
“We will spend the best part of a week lobbying delegates and putting our case as to why it shouldn’t go ahead,” Mr Burkitt said.
The two are signatories to a letter which also has the backing of former Greens leader Bob Brown, and Joan Domicelj, the principal author of the nomination that saw the Blue Mountains granted World Heritage status.
“We submit that the World Heritage Committee request the Australian Government to provide a comprehensive report on the impact of the Warragamba Dam wall raising within the next year and that it be asked to agree that a moratorium be placed upon any state approval processes until the World Heritage Committee has been able to consider its position upon the proposal at its meeting in mid 2019,” Mr Debus wrote in the letter.
The governing body, which can add sites to the World Heritage List, can also revoke a listing or place properties on the list of world heritage in danger.
The proposed increased height of 14 metres would flood up to 1000 hectares of world heritage property and 65 kilometres of wildness rivers and streams, the Colong Foundation says. Indigenous cultural sites would also be inundated.
“If the inundation proposal were to proceed the values and integrity of the Greater Blue Mountains World Heritage Area, Blue Mountains national park, declared wilderness, a declared wild river, national heritage and the special catchment area would be significantly degraded,” Mr Debus wrote.
The proposal was raised in June 2016 by then Premier Mike Baird as flood mitigation in the Hawkesbury-Nepean Valley. It "will offer significant extra protection for townships downstream, including Windsor, Richmond and parts of Penrith," he said at the time.
Australian National University associate professor Jamie Pittock, an environment and floodplain policy expert, said alternatives to raising the dam should be fully considered.
“Supplying more of Sydney’s water from other sources is one option that would enable part of the airspace in the existing dam to be used for flood control,” he said.
“Dams do not stop the most severe floods. Wivenhoe Dam did not save Brisbane from flooding in 2011. Flood control dams lead to downstream development on the floodplain that increases risk.”
University of NSW Engineering Professor Stuart Khan has also spoken of the need for governments to look at diversifying water supply systems to reduce reliance on the Warragamba Dam, like cities around the world were doing.
“We need to look at a system for Sydney where one third of the supply come from the dams, a third comes from potable reuse (recycled water) and a third from seawater desalination,” he told a forum on the Warragamba Dam proposal held in Springwood in March.
Stuart Ayres, the Minister for Western Sydney, said raising the dam wall was “a critical part of the NSW government strategy to reduce flood risk and build community resilience for the 130,000 people living in the Hawkesbury-Nepean Valley.”
“This strategy is about protecting the lives and property of people who live in the valley, it’s not about facilitating inappropriate development,” he said.
“We have found that raising the dam wall is the best option to reduce flood risk. A number of alternative options, including operating the dam differently, were carefully considered.
“We are currently developing an Environmental Impact Statement (EIS) which will outline the environmental, social, and economic impacts of the dam wall raising.”
Blue Mountains Labor MP Trish Doyle said she was “unconvinced of the merits of the dam wall raising proposal” adding it was “a Trojan horse for property developers who want to build on floodplains along the Nepean and Hawkesbury Rivers.”
“It is a bad idea being pushed by an industry that routinely puts its short term profit ahead of good outcomes for the community and the environment, so I do not support it.”