Climate change will put increased, long-term pressure on water levels at the Darwin River Dam, the Top End region's main supply of drinking water, a Power and Water expert says.

Key points: Power and Water says the drinking water level is at 54 per cent

Power and Water says the drinking water level is at 54 per cent Climate change will further exacerbate pressure on the supply, an expert says

Climate change will further exacerbate pressure on the supply, an expert says Industry stakeholders have accused the NT Government of lacking "political will" to fix the issue

Industry stakeholders have accused the NT Government of failing to act on the prediction as both drinking and groundwater supplies hit their lowest ebbs in years.

The dam recorded 52 per cent full before rain this week lifted it to 54 per cent, its lowest level since 2006.

It follows the driest start to a wet season since Bureau of Meteorology records began — ending on January 21 after a needed monsoonal downpour.

"Last year's wet season wasn't particularly good in the dam catchment, so we didn't see a full recharge in the course of the year," Power and Water's Trevor Durling said.

During the past 15 years, the spillway at Darwin's dam has overflown most years. For the past two seasons it hasn't. ( ABC News: Matt Garrick )

Climate change to have impact on supply

Mr Durling said while Power and Water was not immediately concerned about the current levels, modelling suggested there would be more pressure on the dam in the future due to climate change.

"Climate change will lead to increased evaporation throughout the year in our region," he said.

"[And] increased evaporation leads to further pressure on our surface water supplies, and so, we accommodate those changes in our water supply planning moving forward."

Power and Water's Trevor Durling says climate change modelling shows more water will be lost via evaporation. ( ABC News: Matt Garrick )

The dam level drops about 2 metres each year due to evaporation.

Mr Durling said Power and Water was planning its future using long-term "climate change information provided by the Bureau of Meteorology and CSIRO".

"We look at horizons including 2030, 2065 and 2090 to incorporate those planned changes," he said.

Despite the prediction and the falling water supply, no immediate action has been taken by the NT Government to create a second major source of drinking water to futureproof the region.

Mr Durling said there were options on the table but none had yet been decided or acted upon.

"[We need] to understand the demand growth profile from not only urban population growth, but also industry in the region," he said.

Government lacking 'political will', pastoralists say

Industry stakeholders have accused the NT Government of failing to act on futureproofing the region's drinking and groundwater supplies.

NT Cattlemen's Association chief executive Ashley Manicaros said pastoralists were apprehensive of water security amid the looming possibility of more extreme conditions in the NT's future.

"If you follow the climate change argument, then we're going to see droughts more frequently, for longer," Mr Manicaros said.

It is estimated up to 800,000 head of cattle were destocked from the Barkly region over the past 18 months due to drought. ( Supplied: NIAPP )

He said the Government was lacking in "political will" in making a move.

"There is a delay, year-on-year, to when we actually see anything occurring which will allow for substantial commitment," he said.

"There is several hundred million dollars' worth of funds available for water storage through the Federal Government. Yet I'm not aware of any plans by the NT Government to access those funds."

In wet seasons past, this creek has been inaccessible due to water inundation. This year it's all but dried up. ( ABC News: Matt Garrick )

Acacia Hills Farm mango farmer Kris Bailey said groundwater levels at her rural property were the worst she had seen it in a decade, and feared the Government was not acting fast enough.

"I think everyone will struggle for even things like drinking water, not just to keep plants alive," Ms Bailey said.

"[The Government is] a little bit behind the eight-ball. I think they should've come up with maybe more statistics some years ago, before it gets to where everyone's going 'oh, we've got a problem'.

"I think it should've been tagged a while ago so controls could've been put in place already."

NT Natural Resources Minister Eva Lawler said the Government would "continue to work with the community and industry to use the water we have wisely, and to look at how we build our resilience in water supply for the future".

Specifics around what would be done remained unclear.

Water supply future uncertain

Two of the most frequently discussed options for future water supplies are for a new off-river catchment to be built near Adelaide River, or for watersport recreation area Manton Dam to be brought back into commission.

Mr Durling said both options would take years to complete.

Darwin River Dam is at its lowest level since 2006. ( ABC News: Matt Garrick )

"The infrastructure for Manton was constructed in the 1940s, so to return Manton Dam to service would require a new pumping station, pipeline and a water treatment plant … we're probably talking in the five to 10-year timeframe," he said.

An NT Government spokeswoman said agencies were currently "investigating the option to return Manton Dam to service in around 2027".

"Should the need arise to return Manton Dam to service earlier, these potential plans can be bought forward," she said.

Despite calls from both federal and NT politicians to move faster towards a new catchment being built at Adelaide River, no announcements as to its progression have been forthcoming.

A CSIRO report, released in 2018, found an "Adelaide River dam could safeguard Darwin's future water supply and support 8,500 hectares of irrigated agriculture".