February 2025
Burrendong dam was completed in 1967 with public funding for the purposes of flood mitigation and water supply. The dam is located on the Macquarie/Wambuul River about 30km southeast of Wellington. There is an area of Burrendong Dam that is used to catch floods and release them in a controlled manner, giving communities on the natural floodplains a level of protection from floods.
The Macquarie Wambuul Water Security Project includes an option to use some of this space for additional water storage, mainly for cotton irrigation. This blatant water grab would:
- transfer billions of litres of water that is currently important natural flows to irrigation.
- decrease the size of the flood mitigation zone of Burrendong dam and therefore flood protection for the valley.
Healthy Rivers Dubbo strongly opposes this option.
Environmental Impact on the Ramsar Listed Macquarie Marshes
Only when a natural flood occurs do water birds flock to the Marshes in the hundreds of thousands to breed. It’s incredible to see.
These massive nesting events are becoming smaller due to river regulation, having shrunk from events with over a million nests before the dam went in, to about 200,000 at most now. There are significantly fewer wetlands in inland NSW that can host these massive nesting events. Globally, 70% of wetlands have been lost since 1900.
Keeping more water in the flood mitigation zone would cause natural flooding events to be suddenly cut short. This would cause water levels in the Marshes and other wetlands in the catchment to suddenly drop, having a catastrophic impact on mass water bird breeding events.
Flood water has premium environmental value to the entire ecosystem, including the recharge of ground water aquifers. Cutting short flooding events in the Macquarie/Wambuul would have the effect of further sterilising the environment.
Increasing the risk of flooding for Dubbo and Wellington
Reducing the flood mitigation zone increases the risk of an uncontrolled dam spill, which would cause significant damage to property and communities including Wellington and Dubbo. The increased risk of significant flooding in Dubbo would put upward pressure on insurance premiums and erode Dubbo’s reputation as a safe community.
Peer reviewed climate change modelling for the Central West shows flooding will become more extreme in the future – we are already experiencing larger flooding events and downpours:
- Friday 26th November 2022 a record 220,000 ML flowed into Burrendong dam, that’s almost half of the flood mitigation zone size. If the flood mitigation zone had not been available, significant flooding would have been experienced in Wellington, Dubbo, Narromine and other communities downstream of the dam.
- The downpours experienced around the weekend of 7th December 2024 in the upper catchment saw people clinging to trees in floodwater in Bathurst, and cars washed downstream near Mudgee.
As the climate warms there will continue to be a growing list of communities who bare economic, social and emotional scaring from increasingly large floods, for example:
- Eugowra November 2022, two people were killed and about 150 people were airlifted off their roofs when an ‘inland tsunami’ hit the town.
- Grantham in the Lockyear Valley Queensland was devastated by a large flood in January 2011 that killed 12 people – the town has since been relocated.
- Lismore on the North Coast of NSW experienced record-breaking flood that peaked more than 2 metres higher than the record. It was ranked the fourth most costly natural disaster in the world for 2022 – and the second most costly for insurers.
The proposal to reduce the flood mitigation zone in Burrendong dam, exposing all residents along the floodplain downstream of Burrendong dam to increased risk of flooding is wreckless. Communities that are built on floodplains, like Dubbo, must take every opportunity to protect themselves from the worst impacts of increasingly common and severe flooding.
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