Traditional Owners will take their fight over the Northern Territory government's decision to slash the security bond of Glencore's McArthur River Mine and approve the expansion of the mine without a closure plan to the NT Supreme Court tomorrow, 16 February.

Garawa elder and Traditional Owner in Borroloola Jack Green said the original bond was already insufficient to protect the McArthur River and the local area from the impact of the mine, and the Minister's decision to reduce it "doesn't make any sense".

"We don't trust the mine to clean up the mess properly. We need the bond to protect the river and our country if something goes wrong," he said.

"The bond wasn't high enough before – it needed to be doubled at least. It's not enough to repair the damage they've done – that's why we're fighting. No one came down to speak with us about the decision to cut the security bond. They've kept us in the dark – we still don't know why they made that decision.

"We're living with this mine every day, and we don't know what's going on. The government speaks to the mine, the mine speaks to the government, but no one speaks to us."

Gudanji woman and Native Title holder of the McArthur River Mine site Josephine Davey Green said the decision to reduce the environmental bond "could impact the McArthur River and affect her people for thousands of years".

"I am hurting so deeply. I worry for my children, and their children. I am fighting for my country," she said.

"My ancestors spent their lives with that river – it is everything to us, we're all connected to it. It is part of us. We feel like we can't fish there now, and I can't get there to teach my children about culture and country – I have to go elsewhere.

"The government made a decision that could affect our people for thousands of years. If the mine walks away now, that river will be gone, and so will we."

The Environment Centre NT is also a plaintiff in the case.

Centre director Dr Kirsty Howey said the McArthur River Mine "is one of the most toxic mines in Australia, with a sordid history of poor regulation".

"This legal action is an important step in holding the government to account over the regulation of this mine. Glencore has said the rehabilitation and monitoring of the mine could take a thousand years," she said.

"Territorians don't deserve to be left to clean up this financial and environmental mess when the mining company decides to pack up and walk away.

"This case is of national significance. Security bonds are routinely underfunded across the country. It is imperative that there is clarity around closure, or its taxpayers who fix the bill.

"We are proud to be standing with Jack, Josie, and community from Borroloola who have been fighting this destructive mine for decades."

The case is a judicial review of a November 2020 decision by NT Mining Minister Nicole Manison to reduce the security bond required by the government from over $519 million to about $400 million, and to approve an amended mining management plan without a closure plan for the full life of the mine.

The bond has since been increased to $476 million.

The Environmental Defenders Office NT, representing the plaintiffs, will argue on behalf of its clients that the decision to reduce the bond was unlawful and invalid, with the aim of ensuring the Northern Territory government requests enough money from Glencore to properly rehabilitate the site of the McArthur River Mine after mining activities cease, with the environmental impacts of the mine, and in turn, requirements for monitoring and maintenance being likely to occur for 1,000 years.

The mine, an open-cut lead-and-zinc mine in the Gulf of Carpentaria, about 60km from the town of Borroloola, is about 1000km southeast of Darwin in the Gulf of Carpentaria.

The plaintiffs note that the mine has been dogged by environmental problems and criticism over its potential impact on the rich Aboriginal cultural heritage in the area, and that between 2013 and 2014 there were several incidents relating to a waste rock dump at the site, including spontaneous combustion of reactive pyrite that sent plumes of toxic sulphur dioxide across the Gulf country for months.

Local waterways and fish populations have also been found to have elevated levels of lead and other heavy metals.

Environmental Defenders Office chief executive David Morris said "ultimately, it won't be Glencore or the government that has to live with this mine's toxic legacy for the next 1,000 years – it'll be the people of Borroloola".

"The site could have severe, long-term impacts on the environment and the local community if the tailings are not carefully managed and sufficient funds are not set aside to stabilise the site," he said.

"This case is about ensuring Glencore doesn't leave the local community a toxic legacy and the Territory's taxpayers a massive cleaning-up bill. It is also about ensuring the government requires long-term closure plans before it approves projects like these."

Mr Morris described the McArthur River Mine as "perhaps the worst case of a local community having to live with the government's failures, long after the companies and government decision-makers have moved on".

"Our clients want to ensure this cannot happen to another community elsewhere in the Territory," he said.

NT Minister for Mining Nicole Manison told National Indigenous Times: "As this matter is before the courts, we will not be making any comments."

The hearings will take place over two days, Thursday the 16th and Friday the 17th of February. Proceedings will be streamed via the Courts and Tribunals Northern Territory YouTube channel.