Raising Warragamba Dam Wall - The Bushwalker Vol 38 issue 2

First published in "The Bushwalker".

For many bushwalkers reading about a proposal to raise Warragamba Dam by 23 metres will feel like a bad case of deja vu. In the 90’s bushwalkers were at the forefront of the three-year campaign against this proposal — rallying around its impact on the lower reaches of the Kowmung River. Despite winning that battle, with the incoming Carr Government dumping the plan, it appears the war is far from over.

Two decades on, and despite a price tag of at least half a billion dollars, the proposal to extend the existing dam wall upwards by 23 m has been revived and now comes with powerful political backers. Infrastructure NSW took the lead, recommending the wall be raised for ‘flood mitigation’ as part of the 20-year State Infrastructure Strategy. Then Tony Abbott earmarked it in his '100 dams' water plan. Finally Julia Gillard pledged $50 million towards examining the idea. The O’Farrell Government is currently considering the proposal, the Opposition isn’t opposing it, and the insurance industry and land developers have gleefully jumped on the bandwagon.

Despite all this attention, no one has mentioned the plan’s most obvious impact: the inundation of thousands of hectares of World Heritage Wilderness. Worst affected will be spectacular reaches of the Kowmung, Coxs and Nattai Rivers.

Much has changed in the last 20 years. The risk of a catastrophic dam failure — one of the main arguments for the wall raising — has been removed by the $150 million auxiliary spillway. Also, the land that would be flooded by this proposal has not only been added to the National Park estate, it has also been World Heritage Listed.

None of these points have been addressed by Infrastructure NSW in their recommendation that the NSW Government consider raising the Warragamba Dam wall.

Their report estimates the cost of the dam proposal to be ‘at least $0.5 billion’ and recommends it be funded not by government, but by ‘users’, which likely means it would be paid for through a levy on water rates, council rates or insurance premiums.

While there are many reasons to suggest this plan is bad policy, for bushwalkers the most obvious must be its detrimental impact on thousands of hectares of wilderness.

Stationary flood waters backing up behind a raised dam wall would deposit large amounts of silt and debris, coating plants and clogging waterways. Unlike short-lived natural floods, the dam would hold back the waters for weeks or longer, drowning river bank vegetation. Once the bank vegetation is killed it will lead to erosion and weed invasion.

Up to half the surviving population of the threatened Camden White Gum would go underwater during flood events, threatening the species’ very survival. Extra soil stripped from the 7,500 hectares of land that would be intermittently flooded will silt up the dam and smother the lower reaches of the pristine wild rivers that flow into the dam. River banks will be eroded and the slopes will slump. This damage won’t just occur in remote, rarely seen places. At full capacity the waters of Lake Burragorang would reach into the Kedumba Valley — past where the Mt Solitary walking track crosses the river — and even be visible from the Three Sisters. Vegetation scarring would be visible from the most popular tourist destination in the Blue Mountains.

Most worryingly, some of those pushing this proposal see it as an opportunity to open up low lying rural land on the fringe of the north-west growth area for urban development. If the raising of Warragamba Dam lowers the hypothetical level of the one in 100 year flood level — the level modern housing is not allowed below — huge tracts of land could be developed. Infrastructure NSW admits this, saying that approximately 8,000 residential lots and 60 hectares of commercial and industrial land have not been developed due to concerns over flood evacuation routes. On top of those properties, their report states that there are a number of other developments currently in the planning phase where flooding constraints will be a significant factor. These proposed developments ‘include more than 8,500 residential lots and over 150 hectares of commercial and industrial land.’

Clearly the ability to open up these large developments is a major driver behind the latest proposal. Even with the dam raising, for the most extreme floods — one-in-500 and higher — the dam will offer no protection. By comparison, the flooding of Brisbane in 2011 was a one-in- 1000 year event - but it happened. With the current rapid change in climate we can confidentially expect that soon ‘1-in-100 year floods’ will probably happen every ten years - but the public will be exp t the bill for the destruction.

Essentially, a huge amount of public money will be spent on an environmentally devastating piece of infrastructure so developers can open up valuable tracts of land and make a huge private profit. Never mind the tens of millions of dollars in profits to be made from ‘training mines’ and such: the private profits here could be an order of magnitude greater. And all funded by the public purse.

After the Brisbane floods - which were not supposed to happen because they have flood control dams to prevent such an event, one might have wished for a greater understanding about flood plains. They flood! Would insurance companies be willing to insure the area? Very unlikely, because they are not stupid. So just like in some areas in America (eg those affected by Hurricane Katrina) there will be a demand for the government to provide insurance - at a loss.

Interestingly, dam experts say the existing dam could provide flood mitigation without the wall being raised. By installing new flood gates, changing management procedures and improving flood monitoring, substantial flood mitigation could be provided at a fraction of the cost. Additional money could then be used for flood management downstream, such as the construction of evacuation routes. This offers an effective, economically sound and environmentally responsible way of protecting human life on western Sydney’s flood plains.

A community campaign on this issue is already growing, with people from across Sydney and the Blue Mountains coming together to fight this outrageous and damaging proposal. Central to their efforts is the process of raising awareness in the community about this very real threat to some of the most significant wilderness areas in Australia. As bushwalkers, we have the ability to share pictures and stories of our own experiences of some of the majestic rivers that will be damaged by this dam proposal.

Bushwalking clubs can also run walks into some of the areas that will be impacted — from day walks into the Kedumba Valley to longer journeys into the Kowmung — to broaden the number of people who have seen exactly what environmental treasures are at risk. This proposal was stopped twenty years ago, and it can be stopped again. There are thousands of people passionate about protecting our environmental heritage, and thousands more around the world who have experienced the wonder of the Blue Mountains. Together we can be a formidable force.