$1 BILLION dam project to flood Greater Blue Mountains World Heritage Area

Keith Muir, Director, Colong Foundation for Wilderness

There is a very good reason that large dams have not been built in NSW for the last 30 years. Dams, by their very nature, have devastating impacts on the natural environment. Inundation of protected areas, water starvation of downstream ecosystems and cold-water pollution of waterways are just some of the many environmental impacts dams have.

Unfortunately, from time to time, governments still see political opportunity in announcing new dam projects, even when alternative options are available. The latest dam project being embarked upon by the NSW Government is the proposal to raise the Warragamba Dam wall by 14 metres.

Warragamba Dam, located adjacent to the Greater Blue Mountains World Heritage Area, is Sydney’s primary drinking water supply. It holds 2,000 gigalitres of water and is one of the largest dams of its type in the world. In June 2016, then Premier, Mike Baird, announced that Warragamba Dam wall would be raised by 14 metres for flood mitigation. The cost of the project is close to $1 billion dollars.

While at first glance 14 metres may seem small, the increased height of the dam would hold two entire Sydney Harbours, increasing the storage by 50%, and inundate 4,700 hectares of our precious National Parks. The Government is embarking upon an engineer’s solution to what is a complex problem.

Raising Warragamba Dam wall will not eliminate flooding in the valley. The Warragamba River makes up only one half of the Hawkesbury-Nepean Valley catchment area. Flood waters originating from the south-eastern half of the catchment, as occurred in the Picton floods, would not be mitigated against.

Proper floodplain planning, evacuation routes, flood levies, pre-flood release of dam water and the lowering of Warragamba Dam’s present storage level are all alternative measures which can be implemented at less cost, while not destroying parts of one of the most protected natural landscapes in Australia.

Raising Warragamba Dam wall would inundate and destroy 1,000 hectares of the Greater Blue Mountains World Heritage Area, 4,700 hectares of National Parks and 1,800 hectares of declared Wilderness Area. The Kowmung River, one of NSW’s few remaining wild rivers, will be drowned. These areas would be submerged for months at a time. Some of our most-loved Blue Mountains bushwalking destinations, including the Kedumba Valley and Wild Dog Mountains, would be scarred by a permanent ring of weeds and sediment. The sediment ring would be visible from Echo Point, Katoomba. The raised dam would irreparably damage World Heritage Listed environments and put at risk the Blue Mountains tourism industry.

Rare eucalypt and dry rainforest communities would die from sedimentation, erosion and invasion of weeds. There are at least 29 endangered and critically endangered native plant and animal species which inhabit the inundation area. Species such as the vulnerable Camden White Gum (Eucalyptus benthamii) and the Kowmung Hakea (Hakea dohertyi) are predominantly found in the proposed inundation area. A raised dam would put at risk their very existence.

Downstream environmental damage would follow the raising of the dam wall. Longer duration flood events would cause river bank erosion, resulting in a wider and shallower Hawkesbury-Nepean River. Downstream wetlands, such as Bakers Lagoon, depend on natural (short) flood events for replenishment. These wetlands and their associated wildlife populations would deteriorate.

Many Indigenous cultural sites would also fall victim to any raising of the Warragamba Dam wall. The Burragorang Valley was home to the Gandangara people before Warragamba Dam flooded the valley in 1960. The dam drowned large parts of their land and precious cultural sites. We do not need to repeat this story of destruction with the remaining cultural sites in the valley.

History tells us that only people power can stop destructive dam projects. Please, in the coming months, join with us to be part of a growing campaign to save our irreplaceable Blue Mountains environments. Head to dontraisethedam.org.au to sign up, donate and spread the word about the campaign.