Is the proposal to raise Warragamba Dam wall to increase Sydney's drinking water storage?
No. While Warragamba Dam is only used for drinking water supply at present, the proposal is that an additional 14 metres be added to the dam wall to capture flood waters during high rainfall events. During high rainfall events, it is proposed the additional 14 metres of airspace in the dam hold back floodwaters for five weeks at a time. After a flood event, the dam would be slowly emptied to bring the dam level back to its 'full drinking supply storage level'.
What are the environmental impacts of raising the Warragamba Dam wall?
The proposal to raise its wall would increase the dam’s capacity by fifty per cent, placing 65 kilometres of wilderness streams and rivers within the World Heritage site under direct threat from dam water inundation. Australian Government documents obtained through a freedom of information request have said of the dam proposal:
“The impact of increased flood water levels within the dam is likely to have extensive and significant impacts on listed threatened species and communities and world and national heritage values of the Greater Blue Mountains World Heritage Area.”
Who wants to raise the Warragamba Dam wall?
Housing developers. While the dam wall raising was proposed in 2016 by the Baird (NSW Liberal) Government, it is land developers on the Hawkesbury-Nepean floodplain who seek to benefit for the dam wall raising. The NSW Government has itself stated that it plans to allow developers to place and additional 134,000 people on the floodplain once the dam wall is raised - doubling the existing floodplain population.
Who decides if the dam raising can go ahead?
Both Federal and State Governments need to give their approval for the dam to be raised. The Federal government has discretionary power over the proposal as it will breach the World Heritage Operational Guidelines.
The environmental impact statement for the proposal is yet to be release, with both federal and state approvals likely not being decided upon until early 2020.
What are the alternatives to raising the dam wall for existing floodplain communities?
Respected academic authorities have identified alternative flood mitigation measures for existing communities that do not require raising the dam wall. These alternatives including international best practice floodplain development controls, flood evacuation routes, property repurchase schemes, construction of downstream flood diversion structures, and integrated dam management and climate forecasting. You can read more about the alternatives to raising Warragamba Dam wall in a report compiled by Associate Professor Jamie Pittock here.
What are the major political parties position on the issue?
The NSW Liberal Government are the proponents of the dam wall raising. The NSW Labor Party and the NSW Greens have been vocal in their opposition to the proposal, voting against the Water NSW Amendment (2018) Bill that was passed by the NSW Parliament to allow the flooding of national parks resulting from the dam wall raising. NSW Labor Shadow Water Spokesperson, Chris Minns, has said the dam wall raising would not proceed if NSW Labor were elected to government. Neither major parties at a federal level have stated a position on the proposal.
Will the Greater Blue Mountains World Heritage loose its World Heritage status if the dam wall raising goes ahead?
Yes. There is a very real threat that raising the Warragamba Dam wall may result in the de-listing of the Greater Blue Mountains from the UNESCO World Heritage List. This is because it will impact upon the values for which the park was listed. The Australia International Council on Monuments and Sites, an Australian Committee for the body which advises UNESCO, has warned of the potential for the Blue Mountains to be placed on the World Heritage in Danger List if the dam raising were to proceed.
Has raising the dam wall been proposed before?
Yes. In 1992 the NSW Liberal government led by John Fahey proposed a 23m increase to the Warragamba Dam wall. After a business case was developed by NSW Treasury and environmental impacts were considered, the proposal was abandoned by the Carr Labor Government that was elected in 1995.
Is there a map of the rivers and areas that would be flooded upstream of the raised dam wall?
Yes. You can find an interactive map showing the approximate impacted areas of national parks here.
How do we know raising the dam is about floodplain development?
The dam raising is being driven by developer interests on the Hawkesbury-Nepean floodplain. The NSW Government has stated in its principle document advocating the dam proposal that it plans to allow an additional 134,000 people to reside on western Sydney floodplains after the dam is raised.
Minister Ayres, the Minister for Western Sydney has himself said that he plans for future development across the low-lying Penrith floodplain "as far as the eye can see" in the coming years.
More (referenced) information on floodplain development can be found here.