Healthy Rivers Dubbo is pleased to offer our comments on the options for improving water security in the NSW Government’s Macquarie Wambuul Water Security Project.
Provide a drought reserve in Burrendong Dam to Droughtproof Dubbo
Our preferred option is that a 3 – 4 year drought reserve be established in Burrendong dam to droughtproof Dubbo. All that would be required is for a determined volume of water to be reserved, and when the dam got to that level, only water to keep the river itself and towns provided for would be released.
At the moment there is an assumption that the dam will fill up every two years regardless of the outlook and of recent droughts, and there’s no rules to stop the dam from emptying down to zero.
Compared to irrigation, the towns in the Macquarie Wambuul catchment use a tiny volume of water per year, less than 2% of the dam – it is profoundly unjust that entire communities and economies the size of Wellington and Dubbo should be put at risk simply because there isn’t a drought reserve in Burrendong dam.
Based on the limited data that is publicly available regarding water released from Burrendong dam, we estimate that only 11 – 12% of the dam would provide the basics for the river and towns for a year. All that would be required to droughtproof Dubbo for three years is 33 – 36% of the dam.
Expanding the use of groundwater for Dubbo’s water supply
Groundwater is not a magic pudding and cannot be relied on indefinitely. The groundwater reserves under Dubbo are already drawn heavily on to supplement the water Dubbo draws from the river. During the millennial drought, the Government had to order Dubbo to stop drawing so much water from the aquifer as the levels had dropped dramatically. The extent to which groundwater extraction can be increased must be based on scientifically determined environmentally sustainable limits.
The use of Burrendong dam’s flood mitigation storage to increase water supply
There is an area of Burrendong Dam that is used to catch floods and release them in a controlled manner, protecting towns and property from uncontrolled flooding. There is an option in the project to use some of this space for water storage. Healthy Rivers Dubbo strongly opposes this option, as will not improve water security at all – it will simply mean even more water will be released from the dam and consumed in the same short period of time.
- Water supplies would not last any longer than they currently do (i.e. two years), it would just mean that more water would be extracted over the same timeframe
- This option would not offer additional water security for the catchment in a drought
- Increase the risk of dangerous uncontrolled flooding in Wellington and Dubbo
- Catastrophically impact water bird breeding in the Ramsar listed Macquarie Marshes
Pipeline from Dubbo to Nyngan
Healthy Rivers Dubbo accepts the need for a pipeline to Nyngan to secure water supplies out as far as Cobar. However we would prefer to see a pipeline from Warren to Nyngan replacing the Albert Priest Channel, rather than a pipeline from Dubbo to Nyngan.
We are extremely concerned that in a drought, the river would be cut off at Dubbo if that is where the pipeline commenced.
Replace Gin Gin weir
The community resoundingly rejected a proposal for a large new dam to replace the crumbling old wall that remains in the river at Gin Gin.
Any replacement of this old weir must include fish passage, and cannot be any higher, or hold back any more water than the current fixed weir.
Healthy Rivers Dubbo 