Responsible Agency: Seqwater
Proposal Stage of Development: Detailed Business Case Underway
Building Queensland Role: Assisting with Detailed Business Case
Planned Stage End Date: Q2 2018
Estimated Cost of Delivery: $90 million*
Date of Publication: December 2017


Lake Macdonald Dam on Six Mile Creek on the Sunshine Coast requires an upgrade to meet modern standards and the performance requirements of the Queensland dam safety regulations into the future. The drivers for the upgrade include:

  • population growth downstream of the dam
  • advances in dam design and development of consistent methodologies for assessment of dam safety
  • the latest estimates of extreme rainfall
  • data from recent major weather events and updated modelling
  • improved understanding of earthquake probabilities and loads.


The proposal is to upgrade the existing dam to meet the requirements of the Queensland dam safety guidelines. The current project is to develop the detailed design for the preferred option and gain the necessary project approvals to enable construction of the upgrade. The proposed upgrade will reduce dam safety risks by increasing the spillway capacity and the earthquake stability of the dam, while maintaining water supply security.

Studies have considered a range of options including decommissioning of the dam, retrofit of strengthening works and new build options.


The project will ensure the dam meets performance standards outlined in the Queensland dam safety regulations into the future.


Complete Detailed Business Case

* Nominal cost in Australian Dollars 2017, estimate provided by responsible agency.