Traditional owners have launched legal action against the Northern Territory government after it slashed the environmental security bond paid by a massive lead and zinc mine.
Borroloola community residents have taken the case to the Supreme Court to challenge the November decision to lower the McArthur River Mine's bond by almost $120 million.
The Glencore-owned mine - about 800km southeast of Darwin - has been dogged by environmental incidents and claims sacred Indigenous sites face irreversible cultural and ecological damage from its operation.
Lawyers are expected to argue that NT Mining Minister Nicole Manison's decision to reduce the bond from about $520 million to around $400 million was made unlawfully, and the decision is invalid.
Ms Manison said the mine's bond was reviewed annually and reassessed by an independent third party every three years.
"The decision to reduce the security bond was made after a rigorous independent assessment process," she said.
Garawa elder Jack Green said the decision to reduce the bond didn't make sense because it was already too low.
"We don't trust the mine to clean up the mess properly," he said.
"It's not enough to repair the damage they've done - that's why we're fighting.
Gudanji woman and native title holder of the McArthur River Mine site Josie Davey Green said the mine could affect her people for thousands of years.
"I worry for my children, and their children. I am fighting for my country," she said.
"If the mine walks away, (McArthur River) will be gone, and so will we."
Ms Davey Green wants the Supreme Court to ensure the Territory has enough money to rehabilitate the region after mining stops in 2038.
NT Environment Centre director Kirsty Howey said an independent review had estimated the clean-up bill at the site was likely to be more than $1 billion.
"The risks are escalating every year, and the mine and the NT government simply can't keep pace with what's unfolding," she said.
"We're talking about the potential destruction of an entire tropical river system that has sustained Aboriginal people in the region for 65,000 thousand years."
Environmental Defenders Office chief executive David Morris said the case doesn't seek to shut down the mine.
"It is about ensuring the Territory has enough money to fix up the mine site if the company walks away, and protecting the community and the taxpayers from shouldering the costs," he said.
Borroloola community is about 45km from the mine, which was built in the McArthur River's bed after it was diverted by 5.5km.
A recent University of NSW report said waste rock at the mine was emitting sulphur dioxide plumes and a leaking tailings dam was seeping metal and acid into the McArthur River system.
The local Yanyuwa, Garrawa, Mara and Gudanji people have been speaking out against it for decades.
McArthur River Mine general manager Steven Rooney said the mine's environmental performance was subject to Territory and federal oversight and was reviewed on an ongoing basis by the Independent Monitor.
There are also separate Independent Review Boards for our waste rock management and tailings storage facility, he said.
"We recognise that mining can have an impact on the environment and we take our responsibility to minimise potential impacts seriously."
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