UPDATED: The cost of recommissioning the Manton Dam and associated works appears to have blown out by $55 million to $189 million in one year, the CLP Government disclosed on Friday without initially acknowledging it, but said works are nearing completion on the project that will improve water security for the Darwin region.

To date, the works on the initiative funded by the Federal and NT governments, include refurbishing the Manton Dam intake tower, which is now 90 per cent complete, the government claimed, as is the rising main from Manton to Strauss. The Strauss water treatment plant is currently 40 per cent complete, with the steel portal structure already erected and concrete structures underway.

The pump station building is nearing completion at 80 per cent, the government said.

However, the NT Independent reported in May 2024, that the former Labor government awarded a $134 million contract to Exact Contracting Ltd for the Manton Dam project, while the CLP said in its statement on Friday that the cost is now $189 million.

The NT Government and a statement from the Federal Government made no comment on why the costs appeared to have blown out by $55 million.

As of last July, the last time the government publicly mentioned the project, the entire project was still listed as costing $134 million.

Essential Services Minister Steve Edgington said late on Friday evening that the $55 million cost difference was for “other funding” for operational costs to keep the Manton reservoir open to the public for recreational use.

That figure has not been previously disclosed publicly and no reason was offered for why not.

Mr Edgington said he was “advised by Power and Water that the Manton Dam return to service project is on track to be delivered on budget”, but did not say it would be delivered on time.

He said in the original statement released earlier on Friday that the increased capacity at the dam will meet forecasted demand, enhance water security, and support future economic growth in the region.

“Darwin’s water demand is expected to double by 2050, so this work will ensure our community can grow and develop confidently,” Mr Edgington said.

The dam’s return to service by mid-next year will boost the water supply for the Darwin region by adding 7,300 megalitres annually, Mr Edgington added, addressing demand and improving water security to support economic development.

Since the upgrade began in May 2024, Exact Contracting has installed 20km of new pipelines and refurbished existing infrastructure, employing over 70 per cent of local workers, Mr Edgington said.

The dam remains a recreational resource, and the new Strauss water treatment plant will ensure high water quality standards, the government said.

“It’s very exciting to see this project coming to fruition. It will deliver safe and reliable drinking water for people, while ensuring Manton Dam remains accessible for recreational use,” Federal Member for Solomon Luke Gosling said.

The Manton Dam project is being funded through the Darwin Region Water Supply Program Stage 1, which is jointly funded by the Australian Government at $300.6 million, while the NT Government has contributed $27 million, totalling $327.6 million to support local water security for the future.

Note: This story was updated to include Mr Edgington’s explanation that the “extra” $55 million figure was part of “other funding” for “operational” costs associated with keeping the Manton reservoir open for public recreational use, that was not publicly disclosed previously.