Beaconsfield Dam in Victoria is to be partially decommissioned to meet modern safety standards. 

Melbourne Water has announced a partial decommission of the century-old dam in Melbourne’s south-east, with works scheduled to occur in 2025/26.

The project will involve lowering the current water level from 98.5 metres to 94 metres, partial decommission and lowering of the dam crest wall, removing redundant infrastructure and building a 10 metre secondary rock-lined spillway.

Currently, the dam does not comply with Australian National Committee on Large Dams (ANCOLD) guidelines, which is why the works will be undertaken.

Melbourne Water’s General Manager Asset Management Services Tim Wood says that while safety is the main factor in choosing this option, environmental and heritage benefits were considered as well. 

The authority says it is important to ensure Beaconsfield Dam, which was built in the early 1900’s and decommissioned in 1988, remains a permanent water body.

Melbourne Water has engaged independent ecologists to review potential impacts of lowering the water level. 

The ecological report recommended a slow draw-down of the water level over a minimum three-year period to allow the vegetation around the edge of the reservoir to migrate with the changing waterline.

This draw-down of water is scheduled to commence next year.

“Melbourne Water appreciates the significant community interest in our dam safety project,” Mr Wood said.

“We have involved the community and stakeholders in the progress of this project for the past two years and have now reached a decision that we believe is in the best interests of the broader community.

“Melbourne Water will work with the Cardinia Environmental Coalition, appointed by the Department of Environment, Land, Water and Planning (DELWP) as the Committee of Management, to ensure that any works to the dam result in enhancements to the environmental values within the Beaconsfield Nature Conservation Reserve.”