Seqwater Lake Macdonald Dam Work Enters New Wall Foundations Stage

Seqwater says the Lake Macdonald Dam Improvement Project has moved into the foundations stage for the new dam wall, as the state government begins work to identify an additional South-East Queensland dam site.

Sunshine Coast News reported on 29 July that the Queensland Government has allocated $10 million for Seqwater investigations into a new dam location while also committing to restore Lake Macdonald near Noosa to full capacity. The report said the lake is currently linked to a plan to return capacity from 39 per cent to 100 per cent, adding about 4000ML back into the Sunshine Coast and Noosa supply system.

Seqwater's project page confirms the temporary upstream cofferdam and demolition of the old dam wall are complete. The next stage is building foundations for the new wall. The new design includes a split-level concrete spillway, with a lower ogee spillway at the original lake level and an upper labyrinth spillway for higher floods. The aim is to improve dam safety and performance during extreme weather without raising the dam crest.

The project has several moving parts. Seqwater lists lowering the storage, relocating fish to Cooloolabin Dam, constructing the cofferdam, demolishing the existing wall, removing unsuitable foundation material, building the new spillway, reconstructing embankments, improving ground conditions and providing a new outlet works structure for environmental releases into Six Mile Creek.

The timeline is long because dam work is slow by nature. Seqwater says the full process, from cofferdam construction to removal after the new wall is complete, is expected to take about five years, subject to weather and site conditions. The published phases include demolition in 2025-26, new wall and infrastructure construction from 2026 to 2028, and cofferdam removal and rehabilitation in 2028-29. Lake Macdonald is expected to refill naturally to its original full supply level once construction is complete.

For Noosa and the Sunshine Coast, the project sits at the intersection of water security, environmental management and local disruption. Residents need reliable supply as the region grows, but dam construction also means truck movements, noise, dust, vibration, night or weekend work at times, and careful management of downstream flows. Seqwater says heavy vehicle controls include GPS tracking, signage and communication measures around school buses, sign-in systems, boom-gate staggering and minimising truck movements during school pick-up and drop-off periods.

The government's wider dam search adds a second layer. Sunshine Coast News reported Premier David Crisafulli said a new South-East Queensland dam would be needed by the mid-2030s, while Water Minister Ann Leahy pointed to the importance of returning Lake Macdonald to full capacity. The exact locations under investigation have not been publicly identified, and any future dam would face environmental, cost, community and delivery tests before becoming a project.

The immediate local story is more concrete. Lake Macdonald is already under construction, the old wall has been removed, and foundation work is the next step. The long-term promise is stronger water security. The day-to-day reality is a multi-year infrastructure build that local communities will keep measuring against safety, communication, environmental protection and the need for reliable supply as the Sunshine Coast continues to grow.