Mine on tropical island plans to pump pit water into ocean

South32 plans to spend $100 million to pump water from its Northern Territory manganese mine into the ocean as it battles to keep the site open.

The Groote Eylandt Mining Company (GEMCO) has faced huge financial challenges due to ongoing flooding in its pits on the remote island, and the company is planning redundancies.

GEMCO, majority owned by South32, plans to construct about 12 kilometres of pipelines to take up to 80 gigalitres per year from the mine and discharge it into the island's Milner Bay.

The plan has the support of traditional owners via the Anindilyakwa Land Council (ALC), and it has environmental approvals from the NT government.

Traditional owners expect the mine to close in the early part of the next decade.

The new water infrastructure would be in place for the rest of the mine's life.

It is understood South32's production costs have nearly doubled due to excess water management, and it needs to cut about $129 million out of the business.

In its quarterly report, released this week, the company said all production forecasts for next financial year were dependent on the infrastructure being built.

Production for 2025/26 was also below initial forecasts.

In a statement, an ALC spokesperson said it had been discussing the plan with GEMCO and the NT Environment Protection Authority (NT EPA) for more than three years and had confidence in the environmental plans in place.

Further consultation is required because the infrastructure extends beyond GEMCO's mining leases and into Aboriginal-owned land. Work cannot begin without traditional owner consent.

"The ALC is satisfied with the NT EPA's response, and this coupled with the other environmental practices are designed to meet the traditional owner expectations that risk for environmental harm is minimised," the ALC spokesperson said.

An NT government spokesperson said it wanted the mine to continue operating and that the plan had been approved with strict environmental conditions.

"GEMCO is one of the Territory’s most significant mining operations and a major employer and contributor to the Groote Eylandt economy," the spokesperson said.

"The ALC acts for the traditional owners, and on Aboriginal land its consent is a legal requirement. Those discussions are continuing.

"The NT government has supported these discussions where appropriate, while respecting that the agreement is required between independent parties."

A South32 spokesperson said the water would be clean and it would work to "safely and effectively manage elevated water volumes".

"GEMCO currently manages excess water through a range of pathways, including bush discharge and riverine discharge … water is also used at processing facilities and for dust suppression," the spokesperson said.

"The excess water disposal project is intended to become GEMCO’s primary pathway for managing excess water."

The island and mine site were hit hard by Tropical Cyclone Megan in 2024, but it is understood heavy rain in multiple wet seasons was also a factor.

South32's website says it is the world's largest producer of manganese, a key alloy in the production of steel and aluminium.