Seqwater has reached a major milestone in the Lake Macdonald Dam Improvement Project, completing construction of the temporary cofferdam.
The preparatory project by the major water supplier in south-east Queensland marks the end of Phase 1 and will enable the next stage of critical upgrade works to proceed.
Seqwater says it is key step in ensuring the dam is brought up to modern engineering standards and continues to provide safe, reliable water supply and long-term water security for the region.
With the cofferdam now in place and functioning as a temporary dam, the project will transition into Phase 2, which involves the demolition of the existing spillway and embankments.
Demolition is scheduled to begin on April 10, 2026 and will run as a continuous 24-hour operation for approximately 15 days, weather permitting. The accelerated construction approach is designed to maintain safe lake levels and downstream flows throughout the works while protecting the integrity of the site.
“Completing the temporary cofferdam is a major achievement and positions us well to safely transition into next phase of construction,” said Seqwater Executive General Manager Infrastructure Planning and Capital Delivery, Sarah Dixon.
“While weather conditions can change, we have well established plans in place to pause and secure the site should conditions shift unexpectedly throughout the demolition phase. Safety remains our priority every step of the way.”
During the continuous works period, specialist crews will monitor construction activities and environmental controls around the clock.
John Holland Group and Seqwater continue to work closely with the local community, including ongoing one-on-one engagement with adjacent residents to ensure clear communication throughout the project.
Once demolition is complete, construction of the new dam will commence. The redesigned structure will include a split-level concrete spillway, featuring a lower ogee crest at the original lake level and an upper labyrinth spillway to safely manage high-flow events.
The project is expected to support more than 150 jobs over the course of construction, contributing to the region’s infrastructure delivery and water security needs.
