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In October 2022, the Goulburn River and the Campaspe River experienced major flooding with flood waters causing significant damage to farms, townships, roads, water supply infrastructure and communities.
Following these floods, we are undertaking an assessment of the operating arrangements for Lake Eildon. This is to determine if changing the operating rules could have any material opportunities to mitigate flooding downstream (Eildon to Seymour) and any associated financial and non-financial implications of such changes.
In delivering this assessment, the rights of existing entitlement holders are a key consideration in any potential changes to operating arrangements. This assessment will clearly document the impact any changes to operations would have on existing entitlement holders, downstream landholders and other users.
The outputs from this assessment will be a valuable resource to the community and will be available to local councils and Goulburn Broken CMA in future reviews of flood mitigation options downstream of Lake Eildon.
The assessment will:
- Develop and assess operating arrangement options and operating rules (taking into consideration current operating rules) for Lake Eildon for the purpose of flood mitigation.
- Design a methodology and deliver a flood impact investigation to identify how effective each operating arrangement option for Lake Eildon would be at reducing flood frequency and peak flows downstream and mitigating the flood risk (i.e., inundation of public and private land and infrastructure) when compared to current operating arrangements.
- For each operating arrangement option that has a material opportunity to mitigate flooding downstream, undertake an impact assessment which identifies any costs, risks and benefits (including modelled changes to reliability) on how the changes would affect existing entitlement holders, landholders and other users.
An independent consultant will be engaged to undertake the modelling and develop a report.
The assessment is technical and therefore there will not be a formal round of community consultation. The assessment is being conducted in consultation with local councils, water corporations and CMAs. Community members can speak to their local council or CMA about any comments or questions relating to the assessment.
The department is leading this work to allow all agencies to provide input in line with their functions and responsibilities. The time to deliver the final report reflects the detailed modelling and assessment which needs to be undertaken.
The final report will be made publicly available and can be used by local councils and Goulburn Broken CMA in future reviews of flood mitigation options downstream of Lake Eildon.
Deliverables and timeline
Scoping document developed and reviewed by key stakeholders
Independent consultant engaged to undertake assessment and prepare report
Final report released
Lake Eildon has operated to a set of filling targets during the winter and spring months since 1959.
The current filling curve has been in use since 2012, with the objective of filling the storage in 19 out of 20 years to protect the reliability of water entitlements while offering some flood mitigation.
Goulburn-Murray Water (GMW) is the storage manager for Lake Eildon.
The Bulk Entitlement (Eildon-Goulburn Weir) Conversion Order 1995 (Goulburn BE) prescribes how GMW is to harvest, store and supply water to its entitlement holders.
Lake Eildon’s full supply level is 288.9 m AHD, at which it holds 3,334,158 ML. In October 2022, inflows to Lake Eildon peaked at 145,000 ML/day while releases were able to be maintained at a peak of 38,000 ML/day.
There are no infrastructure constraints to the operating arrangement options currently identified. The outlet through the hydro-power station turbines has a maximum capacity of approximately 17,000 ML/day.
The gates on Lake Eildon Spillway are operational at 77% capacity, which is the top of the sill level of the spillway.
The GMW website provides more information on the flood event in October 2022.
Page last updated: 08/09/23