The proposed Adelaide River project is expected to boost Darwin's water supply by up to 67.5 gigalitres per year, NT Minister for Water Security Eva Lawler says.
"Securing a safer, more reliable and more sustainable water supply for Darwin is essential for the region's future growth and economic prosperity," she said on Tuesday.
The project has two components - the Adelaide River off-stream water storage project and the Manton Dam, which is set to return to service.
The dam will come online within four years and the off-stream project will be complete in seven to 10 years.
An environmental and social impacts assessment will be undertaken, along with further stakeholder and community engagement.
The projects will help the NT government supply an additional 7300 megalitres of water per year to the Darwin region.
The dam and Adelaide River are an economically viable solution to provide water security to the Darwin region for the next 50 years and beyond, Ms Lawler said.
About 90 per cent of the NT's water supply comes from groundwater, according to the territory government.
The quality of groundwater varies so not all of the territory's 35,000 bores produce drinking water.
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