US mining giant Alcoa will have to stay further away from Perth's drinking water sources amid heated debate about the potential impact its bauxite mining could have on waterways.
The temporary order by the state government forms a key part of a broader environmental assessment for Alcoa's mining operations in jarrah forest south-east of Perth.
The miner has been operating there for more than six decades but is only now being scrutinised by the state's Environmental Protection Authority for the first time.
That scrutiny would ordinarily require works to stop, but an exemption granted by the government in 2023 allowed operations to continue under certain conditions in an effort to "safeguard local jobs".
A new "enhanced" order was issued today, in what the government described as an effort to "ensure Alcoa is meeting government and community expectations".
Environment Minister Matthew Swinbourn said the new conditions would strengthen protections for drinking water and black cockatoo habitat while recognising the miner created jobs for locals.
The new rules will ban Alcoa from mining within 50 metres of black cockatoo nesting trees and other significant trees, up from 10 metres currently.
The miner will also be required to survey areas where it plans to mine to identify those trees, provide the government with their locations and mark the area around the trees in which work is prohibited.
Greens environment spokesperson Jess Beckerling said the changes were welcome but in many cases did not go far enough.
"While a 50-metre buffer is better than a 10-metre buffer, it still doesn't guarantee the survival of these critically important trees," she said.
Intense debate over water
Alcoa will not be able to mine within two kilometres of any water reservoir, up from one kilometre previously.
That's a sticking point advocated for by the Water Corporation, in an effort to protect Perth's drinking water supply.
Over the years Alcoa's operations have moved closer to Serpentine Dam, raising concerns, although there is no evidence the company has ever impacted drinking water.
Intense back-and-forth discussions between the company, state government and Water Corporation emerged in documents related to the EPA's assessment process.
Documents released under Freedom of Information laws to online publication Boiling Cold revealed the Water Corporation had also asked for a ban on mining in steep terrain.
"Slopes greater than 16 per cent have been identified as impacting erosion in rehabilitation areas and mine site failures," the utility warned.
In a 2025 internal drinking water assessment, Alcoa said it would generally only clear areas with less than a 16 per cent slope, but where that could not be achieved it would prepare a drainage management plan.
Further conditions possible: Premier
In a statement, an Alcoa spokesperson said it welcomed the government's decision and was focused on meeting "evolving community expectations".
"We are committed to operating in line with our stringent operational requirements which provide strong protections for the environment," they said.
The company said it employed around 4,000 people in WA with around 60 per cent living in the Peel and South West regions.
Premier Roger Cook indicated further, more stringent conditions, could be imposed in future.
"We'll continue to work with Alcoa around modernising their state agreement which will further bring them into a modern environmental protection regime," he said.
"This latest move is about making sure the instruments that we have available to us today are effective and relevant in relation to their current mining activity."
The Conservation Council of Western Australia's Matt Roberts said the government should instead be focused on closing down the mine.
"What we're seeing is slightly stricter conditions that will enable and continue the destruction of the jarrah forest, the world's only jarrah forest, that cannot be rehabilitated back to the state that it is in at the moment," he said.
"What we're not seeing is a move towards what it means to end mining in the jarrah forest, which is the leadership that we need from the government at the moment."
