A LEADING environmental group has lodged an appeal against a state government decision to approve a revised licence for Alcoa’s Wagerup alumina refinery, citing concerns over rising mercury emissions and potential impacts on nearby ecosystems.

The Conservation Council of WA (CCWA) has challenged the Department of Water and Environmental Regulation’s (DWER) decision, arguing environmental and public health risks have not been adequately addressed.

The refinery, located about 120km south of Perth, sits near jarrah forest and habitat supporting threatened species including black cockatoos and numbats.

A recent licence review found mercury emissions from the refinery have increased since 2023, with about 400kg released in 2025 - nearly double 2022 levels.

CCWA executive director Matt Roberts said the increase raised serious concerns about both the operator and the regulator.

“It seems Alcoa has seen increased mercury emissions from the Wagerup refinery for at least three years, with no action taken to remedy that,” he said.

“This raises serious questions about our state regulator’s capacity to effectively hold the miner to account.”

Mr Roberts said the spike in emissions was not identified through compliance reporting but instead through the National Pollutant Inventory.

Alcoa has attributed the increase to higher mercury levels in ore and issues with condenser performance.

However, CCWA disputes this explanation, warning mercury — a toxic substance that can accumulate in soil, water and wildlife — poses a long-term risk to surrounding ecosystems.

The group also raised concerns about limited environmental monitoring, particularly in areas supporting threatened species within a 2km radius of the refinery.

The appeal argues the decision report failed to fully consider cumulative environmental impacts and calls for stricter monitoring and emission controls.

A DWER spokesperson said the licence extension had been referred to the Office of the Appeals Convenor and it would be inappropriate to comment while the process was ongoing.

Alcoa has been contacted for comment.