Stockton open cut mine closed in 1957 leaving behind a 30-metre deep void that gradually filled with water.

These days the 15 hectare lake, located 2.5 hours from Perth, is a major tourism drawcard that attracts hundreds of camping and water sports enthusiasts each year.

And it's a vision that could be coming to the Upper Hunter in decades to come.

The Hunter Lakes Corporation is working on an ambitious plan to repurpose the region's existing mining voids by utilising them for water storage and interconnecting canals.

When complete the project could eventually stretch 60 kilometres from Muswellbrook to Broke.

The company is in negotiations with the mining companies to use three voids as the foundation of the lakes system. Assessment of another four voids will commence this year.

The proposal is modelled on Europe's largest artificial lake system in eastern Germany, where old coal mine pits have been turned into recreational lakes, with cycling paths and watersports.

The Lusatian Lake District, a former lignite mining wasteland, has been transformed into a chain of artificial lakes stretching across the north-eastern part of Saxony and the southern part of Brandenburg.

In addition to a tourist attraction, the area also provides drinking water to Berlin.

The Hunter Lakes Corporation is presently seeking major project status from state and federal governments to enable it to progress the project.

"We have engaged with all political parties both state and federal. All politicians are in favour of exploring the Hunter Lakes Scheme in detail owing to the enormous benefits it will deliver to communities and the state. It will also prevent the voids becoming saline sinks," Hunter Lakes Corporation director Greg Story said.

"[The lakes] is a revolutionary advancement in environmental rehabilitation and management in Australia,

"It will provide water storage greater than Warragamba dam and providing water security for urban and irrigation purposes for the entire Hunter, Central Coast, Mid North West and Liverpool Plains."

It will also provide an opportunity to create a major renewable energy hub on the state's main energy transmission network in the Hunter providing floating solar, wind and pumped hydro.

Cherie McCullough has been investigating the potential for mining voids to be repurposed as lakes since the 1990s.

While the concept of repurposing mining voids is relatively new in Australia, overseas examples show how nature has slowly been achieving the same goal at some of the world's oldest mining sites.

"If we look back at even things like peat that was mined by the Romans thousands of years ago in the UK, we can see bogs and things, which are essentially shallow mine voids," Dr McCullough said.

"They've naturally rehabilitated to the point where they are highly valued for things like birdwatching and wildlife habitat and other forms of passive recreation. It's been a completely organic process."

Dr McCullough, who works as a consultant specialising in the planning and management of pit lakes, was among the first to explore the opportunities to repurpose abandoned mining voids in Australia in 2006.

"It's my most cited paper throughout my professional career. I wanted to cite some of the opportunities for end uses using Australian examples because we'd had pushback from industry, academia and government saying 'no, it's all about managing risk rather than identifying opportunities'," she said.

"It took finding coherent examples from around the country to demonstrate that wildlife habitat and water resources recreation are all valid uses. They may have occurred in an ad hoc fashion, but if they were planned for they could achieve much more utility than we're seeing at the moment."

Since then the sustainable pit lake movement has gathered pace with communities, mining companies and even regulatory authorities openly discussing the benefits of repurposing mining voids into waterways.

Improvements in remediation technologies have also helped make the process faster and safer.

But not everyone is on board. Critics argue that regardless of how much effort is put into the lake's establishment, the void's latent mineral content will inevitably cause the water to be highly acidic or saline or contain heavy metals.

A 2016 Energy and Resource Insights report, 'The Hole Truth' estimated that one pit at the Mount Arthur mine could contain a million tonnes of salt after 500 years.

Lake Stockton's acidity can vary considerably from the top (mean pH of 5.5) to the bottom (mean pH 4.8).

It is believed this is caused by ingress of groundwater in the underground mine workings, which are still connected to the lake.

The lake was closed temporarily in 1994 when pH levels dropped below 4.5 which is the Australasian contact standard. Limestone chips and then sodium hydroxide were added to fix the problem, without success.

While the lake's acidity is a barrier to most aquatic life, it has also been known to yield some decent sized marron (freshwater crayfish).

"From a scientific perspective, they are not safe enough but from a socio-political perspective, we are seeing the state government (Western Australian Department of Environment and Conservation) encourage the utility of those areas," Dr McCullough said.

"From other examples, we know that saline water has a lot of uses - Salt Lake City in Utah, the Dead Sea in the Middle East, these are all areas that don't meet swimming guidelines from a salinity perspective and yet we see them being used regularly.

"It's my experience working in an outback area in Western Australia people will go swimming in a very saline lake in the middle of nowhere because when you don't have any other water around any water looks quite good. So from a scientific perspective it's about water quality but from a social perspective it's about availability."

Dr McCullough said she believed the several of the Hunter's mining voids would be suitable to be transformed into a lakes system.

Research conducted about a decade ago concluded that most of the region's mining voids were suitable to be adapted for a variety of alternative uses, including lakes.

"I think there's tremendous opportunity in the Upper Hunter Valley. I have been singing from that song sheet for almost a decade now and hopefully starting to see some development in that area," she said.

"Certainly from visiting the area and working in the area and comparing those experiences with international experiences, we know that the water quality is good enough to facilitate many uses.

"We also see that there are enough regional centres nearby that people will be able to travel to the lakes."

Mr Story said the company had been advised that, based on average rainfall, it would take about three years to fill the voids.

The lakes would also become bird and wildlife habitats for native species under threat as well as offering the backbone for a new planned urban landscape to be developed integrating new industries, horse breeding, farming, residential corridors, designated green spaces, national parks and attract tourism for leisure activities.

"The lakes would become new sources of water storage for use by communities and farming as far north as Tamworth and west to Gunnedah and offer drought proofing for the wider district," he said. "It is estimated the area could progressively accommodate a population exceeding 300,000."

A 2019 Upper Hunter Mining Dialogue study into potential beneficial reuses of the Hunter's mining voids identified several significant positives for pit lake end use development. These included proximity to people, access to good infrastructure and predicted good water quality of pit lakes.

"These positives are a strong basis for planning future diversification of the economy with potential for development of alternative industries," the report said.

"There was uncertainty regarding some of the weaknesses and threats, which highlighted significant information gaps. "These information gaps included risks of pit lakes to regional groundwater and surface water.....'

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