Early works underway on Lake Macdonald Dam upgrade

Early works are now underway on Noosa’s Lake Macdonald (Six Mile Creek) Dam upgrade in Queensland and the final design concept has been released ahead of major construction, which will begin in mid-2024. 

The project is part of Seqwater’s Dam Improvement Program that aims to enhance water security and enable the dam to withstand a 1-in-a-500,000-year flood. 

This is the first major upgrade on Lake Macdonald Dam since it was built in 1965 and is estimated to create over 150 local jobs. 

“I’m pleased to see progress on this critical project. This important upgrade will ensure the longevity of Lake Macdonald Dam so it can continue to provide water security and dam safety for years to come. 

“Dams in Queensland are built to very high, internationally accepted safety standards, but methods used to estimate extreme weather and flood risks have changed significantly since come were built. 

“This is one of several important dam safety projects being undertaken by Seqwater. Since 2015, Kinchant Dam, Eungella Dam, Wappa Dam, Boondooma Dam, Leslie Harrison Dam, Fairbairn Dam, and Sideling Creek Dam (Lake Kurwongbah) have been completed across Queensland. 

“With construction starting soon, the upgrade is also set to boost local employment opportunities in the region, with around 150 jobs expected to be created over the life of the project,” Minister for Water Glenn Butcher said. 

Source: Seqwater

The Lake Macdonald Dam Improvement Project includes building a new split-level concrete spillway and upper labyrinth and reconstructing the existing earth embankments. 

A comprehensive technical review undertaken in 2021 and 2022 resulted in a new optimised design that will increase the dam’s capacity to withstand extreme weather events while, at the same time, ensuring the dam remains operational during the construction for water security and some recreation activities. 

Seqwater has ensured that the lake water level is maintained as high as possible during construction. To enable construction to be carried out safely, the lake is going to be temporarily lowered and a temporary cofferdam will be installed to support water security during construction. Meanwhile, the Noosa Water Treatment Plant will continue to be operational during construction. 

“While Lake Macdonald Dam continues to operate safely, the upgrade will ensure the dam meets updated engineering and safety standards, taking into account extremely rare weather scenarios and climate change. 

“The revised design will allow water to be retained in Lake Macdonald during construction, some recreation activities to remain open, reduced impact on aquatic life, plants and animals in and around the lake, and will ensure Noosa Water Treatment Plant continues to operate for local water supply. 

“Projects of this scale are complex and require significant planning time and we thank the community for their understanding while we undertook this important work,” Seqwater CEO Neil Brennan said. 

Survey works are now underway on-site, with site establishment and lake lowering to happen over the coming months. Major works on the temporary cofferdam will begin in mid-2024 after a contractor has been appointed. 

During construction, some recreational use of the lake and surrounding areas will be disrupted due to the project's significant nature. Recreation activities at Lake Macdonald, Lake Macdonald Park and the Noosa Botanic Gardens, however, will remain open. 

Seqwater will keep the community up to date throughout the project’s life, with information sessions to held in early 2024 where the project team will be available to provide information on the design and construction approach as well as answer any questions. 

Source: Queensland Government – Media Statements; Seqwater (1, 2)