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Lake Macdonald Dam upgrade

At Seqwater, some of the dams we operate were built decades ago and, just like cars, they need regular maintenance to keep them in good working order and meet changing safety standards.

Lake Macdonald is one of a number of dams in South East Queensland to be upgraded as part of Seqwater’s Dam Improvement Program.

Lake Macdonald Dam upgrade revised timeline
DAM SAFETY REVIEW
2012-14
OPTION ANALYSIS & CONCEPT DESIGN
2014-15
PRELIMINARY DESIGN & APPROVALS
2016
DETAILED DESIGN & APPROVALS
2017-19
PROJECT PLANNING
2019-20
CONSTRUCTION
2020
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Home What We're Doing Lake Macdonald Dam upgrade

The Lake Macdonald Dam upgrade will be the first major safety upgrade to the dam since the walls were raised in 1980. The dam safety upgrade will involve building a new spillway and reconstructing the existing earth embankments to better protect the dam against earthquakes and extreme floods.

Project update

Seqwater has been undertaking studies to minimise any environmental impacts associated with the dam safety upgrade.

As a result of the studies, Seqwater has updated its initial design of the dam spillway and re-phased the lowering of the lake to 2021 to meet environmental conditions. The lake will now remain open to on water recreation activities during 2020.

In 2020, Seqwater will commence replacing the road bridge to the Noosa Water Treatment Plant and the undertake the relocation of existing utilities and services. Seqwater will also undertake water security projects to improve the operational capability of the SEQ Water Grid ahead of the lake lowering. These projects will bolster water supply security for Noosa and the Sunshine Coast.

The final timing for the lake lowering phase of the project remains subject to further water supply security assessments in 2020 and early 2021. These assessments will take into account the dam storage levels and the water consumption in South East Queensland.  

Lake Lowering

To undertake the construction work safely the lake’s water level will need to be significantly lowered to about 5 to 10 per cent of its full supply level. Lowering water levels is an industry accepted practice to manage dam safety and bank stability during upgrades. Seqwater will be maximising production from the Noosa Water Treatment Plant ahead of any lowering, as well as making its required environmental releases into Six Mile Creek.  The lake will return to the current Full Supply Level following completion of the construction work and adequate rainfall.

 

Impact assessment and approvals

Seqwater collected feedback from the community on the potential project impacts and ways to avoid or reduce them between August and September 2018. The feedback provided informed the Impact Assessment Report (IAR), a document required by the Coordinator-General under the State Development and Public Works Organisation Act 1971. The areas assessed included, but were not limited to, traffic, noise, dust, water quality, recreation, cultural heritage, and ecology.

The public submission period for the IAR was between 11 February 2019 and 11 March 2019. The Coordinator General reviewed these submissions and approved the project in May 2019, subject to a number of conditions. The IAR document and the Coordinator General’s conditions can be located here.

In 2019, Seqwater received the required financial and federal environmental approvals to proceed with the dam safety upgrade.

If you have any questions or concerns about the project, please check out our FAQs below or email the team at [email protected]

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    Updated dam upgrade design will help protect aquatic life

    Updates to the design of the new Lake Macdonald Dam spillway are being made to better protect aquatic life in the dam storage.

    Seqwater Chief Executive Officer Neil Brennan said the project received Commonwealth approval last month clearing the way for the project to commence.

    “The full reconstruction of Six Mile Creek Dam at Lake Macdonald will increase the dam's resilience to extreme events and bring the dam in line with modern engineering design standards,’’ he said.

    Seqwater has been undertaking studies to minimise any environmental impacts associated with the construction of the new concrete spillway and new embankments either side.

    Boats fitted with special sonar equipment have been traversing Lake Macdonald to identify and count fish species in the water.

    As a result of the studies, Seqwater has updated its initial design of the dam spillway and rephased the lowering of the lake to 2021 to meet environmental conditions.

    The project will start next year with a range of construction works including replacing the road bridge to the Noosa Water Treatment Plant and the relocation of existing utilities and services.

    The re-phasing will also allow Seqwater to complete a range of projects to improve the operational capability of the Water Grid ahead of the lake lowering. These projects will bolster water supply security on the Sunshine Coast.

    Mr Neil Brennan said the new design of the spillway, would better assist the passage of aquatic life moving over the spillway when the storage was at capacity.

    “The revised design features what’s known as an ‘ogee-style’ spillway which allows fish and turtles in the storage to slide safely into the pooled water below,’’ he said.

    “The new timeline for the lake lowering will provide us with more time to finalise our aquatic management plan to allow the safe lowering of the dam and the relocation of aquatic life.

    “It also enables us to meet one of the strict conditions of approval for this project: to only lower the lake in a narrow window between March and August, outside the wet season.

    “The lake will now remain open to recreation activities during 2020.”

    The lake lowering and project timing remains subject to further water supply security assessments which will be undertaken during 2020 and early 2021.

    The Lake Macdonald project is part of Seqwater’s Dam Improvement Program - a rolling program of dam upgrades across South East Queensland to ensure Seqwater's dams meet national and state safety standards into the future.

    For more information about the Lake Macdonald Dam project visit www.seqwater.com.au/project/lake-macdonald-dam-upgrade

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