Potential new dams and upgrades along the Lachlan River and raising the wall level at Wyangala Dam by 10 metres feature prominently in the WaterNSW 20-year infrastructure options study for rural river valleys announced this month.
WaterNSW has undertaken the two-year study to address future challenges in operating regulated river systems, with potential to enhance service levels and guide future investment.
In the study WaterNSW identifies four sites as preferred options for potential new dams in the Murrumbidgee, Border, Gwydir and Peel valleys, in addition to several more potential dam sites in the Murrumbidgee, Tumut, Gwydir, Namoi, Lachlan, and Hunter valleys.
According to the study, the Lachlan Valley is believed to have some of the poorest levels of water security and reliability in the state in terms of regulated/licensed irrigation and urban water supply.
The report points out the region was dramatically impacted by the millennium drought.
WaterNSW is currently undertaking a detailed study on how to improve water security and reliability in the Lachlan Valley.
As part of the development of the Lachlan Valley Water Security Study, WaterNSW has developed a detailed hydrological model of the system.
Long-term infrastructure options developed to address water supply security and reliability in the Lachlan Valley include:
- Raising Wyangala Dam by 10m at a cost of $650 million.
- Constructing a pipeline between Carcoar Dam and Lake Rowlands at a cost of $17 millon.
- Raising the Lake Rowlands Dam on behalf of Central Tablelands Water for urban water supply at a cost of $58 million.
- Constructing a new 700 GL dam at the Abercrombie site at a cost of $1000 million.
- Re-regulating weir on the Belubula River at Cranky Rock at a cost of $30 million.
- Constructing a new 700 GL dam at the Cranky Rock site at a cost of $1001 million.
These options will be assessed in detail under the current Lachlan Valley Water Security Study.
Other options identified to improve the long-term level of service of the Lachlan include rationalising the Mid Lachlan effluent system by closing inefficient creeks at a cost of $4 million to improve the delivery efficiency in the mid Lachlan and changing thee size of outlet valves at Wyangala Dam at a cost of $5.4 million.
Infrastructure options considered for improving the delivery efficiency throughout the Mid Lachlan include:
- Constructing new regulating stop-board structures at the entrance to Jemalong and Carrawobitty Creeks at a cost of $42 million.
- Building a new weir upstream of the Jemalong and Carrawobitty Creeks at a cost of $34 million.
- Building a new weir on the Lachlan to better control flows into the Island Creek system at a cost of $44 million.
- Building a new pipeline from the Lachlan to service customers in Wallamundry and Wallaroi systems at a cost of $93 million.
- Rationalise the Mid Lachlan effluent system by closing inefficient creeks at a cost of $21 million.
- Rationalise the Mid Lachlan effluent system by closing inefficient creeks at a cost of $4 million.
Funded by customers, the report is available in full at https://www.waternsw.com.au/projects/20-year-infrastructure-options-study
It identifies infrastructure investment options across all major rural river valleys, along with cost estimates, as part of a ground-breaking study that incorporates factors such as likely agricultural trends, population changes, climate variability and demand fluctuations.
Feedback on the plan can be provided by visiting www.waternsw.com.au/customer-service/news/online-community