The concept has been endorsed as a legitimate option given the temporary life span of mining operations and is inspired by an artificial lake region in Germany.
The former coal mining region in the Lusatian Lake District near Berlin was converted into a recreational water system that also provides the German capital with drinking water.
Hunter Valley Lakes Corporation has pitched the concept of interconnected lakes stretching over 60 kilometres to be filled in three years based on average annual rainfall data.
“This project can be the modern day Snowy River hydro scheme underpinning economic, social and environmental progress for northern NSW,” the corporation’s director Greg Story told The Sydney Morning Herald.
The company is proposing that one of the voids to be filled would hold 193 gigalitres of water, compared with the 500 gigalitres the Sydney Harbour holds.
“The project will be a significant economic engine to drive agriculture, viticulture, forestry, recreation and sports, and renewable energy,” Mr Story said.
NSW Water Minister Melinda Pavey confirmed to news.com.au the government is considering the extraordinary proposal but said more work was needed to understand if the leftover mines would lead to contamination.
“We will always work to best practice and look at new ways to secure water, such as recycling,” she said.
“The NSW Government’s priority is to secure critical town water supplies for all residents across NSW during the current drought.”
The minister cited the Wyangala Dam wall raising and Dungowan Dam as evidence of its existing plan to battle the crippling drought, as well as exploring a case study for Mole River near Queensland in October.
“The NSW Government has already invested in 60 bores and 14 pipelines across the state,” she said. “We’re increasing the height of weirs in places like Wilcannia, Tamworth and Walgett.
“We have built 40 sewerage treatment plants and 31 water treatment plants.”
But Mr Story squashed the government’s reservations on water quality, insisting the artificial system could be purified to drinking standards over a period of three years.
“This enables supply into the Hunter water supply system and recreational use, which has even higher standards of quality and purity,” he said, according to The Herald.
“There is no adverse impact for the Hunter river system. The scheme will augment and strengthen the capabilities of the Hunter River to provide domestic water and irrigation.
“We have met with ministers and mining companies and communities, all of whom are in favour of the concept.”
Alluvium Consulting environmental engineer Misko Ivezich, who specialises in river health and restoration, said a number of factors needed to be considered but the “concept has merit and worth further exploration”.
He told news.com.au the water would need significant treatment before being drunk, while the potential impact to river stream ecosystems, particularly fish, would need to be investigated as well as nearby reservoirs and underground water storage.
“We would still need to know where the water to fill the reservoirs would come from as they would need some catchment,” he said.
“They could divert floodwaters from nearby streams without impacting on river low flows which would not have significant impacts on river ecosystems.”