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Water Corporation looks to EPA to shield Perth's water supply from Alcoa and Roger Cook
WA Premier Mark McGowan told Alcoa in 2023 that it must better protect Perth's water supply or face curtailed mining and "significant job losses," but nine months later his successor, Roger Cook, folded and did the opposite.
Now Water Corporation, which considers contamination of its dams from Alcoa's strip mining a certainty, wants the independent EPA to back reinstating the protections Cook removed.
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WHY IT MATTERS
· Dams are vital: in addition to collecting runoff, in winter they store excess desalinated and bore water for summer use.
· Alcoa's strip mining near Serpentine Dam increases the risk of contamination with sediments, pollutants and pathogens.
· Contamination could require widespread use of bottled water and cause long-term water restrictions.
· Alcoa produces more than 70% of its bauxite and alumina in WA, where it employs thousands of people.
At stake is the water supply system for more than two million people in WA’s capital and South West and thousands of jobs at Alcoa.
After a worst-case contamination from Alcoa's mining in six hours 100,000 Water Corporation customers could need bottled water, followed by widespread long-term water restrictions.
Documents obtained by _Boiling Cold_ freedom of information requests reveal the tussle between the $US13 billion aluminium giant and Water Corporation, and the very different approaches of two Labor premiers.
## Water contamination danger
Almost all of Alcoa's strip-mining of jarrah forest since 1963 has been in water catchments in the Darling Range. There, dams collect runoff that supplies about a quarter of Perth's water and, over winter, store excess bore and desalinated water for use in summer.
In recent years, Alcoa's mining has moved north into hillier country closer to Serpentine Dam - the system's largest reservoir.
The proximity to the water's edge and steep slopes has increased the risk of sediment contaminating the dam after a heavy rainfall, making the water impossible to treat for human use.
Alcoa's operation is vast - it is allowed to strip mine 800 hectares a year - the equivalent of two Kings Parks - and is responsible for 49 square kilometres of cleared land in the jarrah forest, as at December 2025, more than twice the size of Rottnest Island.
The public was unaware that Alcoa's then low-profile operation less than 60km from Perth's CBD threatened their water supply until a leaked government briefing was reported in February 2023.
It revealed that runoff containing sediment, chemical pollutants and disease-causing pathogens could render water undrinkable for years. Fixing the problem could cost billions of dollars.
****More than two million people in WA's South West depend on a complex and highly integrated water system.**** __Image: Water Corporation submission to EPA.__
## McGowan to Alcoa: shape up or else
Weeks later, WA Premier Mark McGowan wrote to Alcoa demanding it demonstrate it could effectively protect Serpentine Dam's drinking water and improve its forest rehabilitation.
A _Boiling Cold_ freedom of information request obtained the letter, but for a further eight months Alcoa objected to releasing one redacted paragraph.
The miner only relented after the Information Commissioner made it clear she was about to rule in favour of disclosure.
The crucial paragraph reveals how serious the Premier was about Alcoa: improve or the government will restrict your mining, even at the cost of many jobs.
> **"The Western Australian Government is concerned that if Alcoa does not appropriately address these issues, this could result in significant job losses due to the halting of future operations."**
> WA Premier Mark McGowan to Alcoa 29 March 2023
Two months later McGowan announced a surprise retirement.
His deputy, Roger Cook, won the Labor Party vote to replace him after the Australian Manufacturing Workers’ Union, which covers Alcoa's refinery workers, abandoned the candidate of its own Left faction to support him.
By the end of the year the outlook would be better for Alcoa, but bleak for the security of Perth's water supply.
## Cook to Government: jobs before water
Roger Cook soon had an opportunity to write some new rules for Alcoa.
In August 2023, the WA Environmental Protection Authority called for public comment on whether it should assess Alcoa's mining.
Under WA's Environmental Protection Act, it is illegal to progress a proposal the EPA is assessing, meaning that if the watchdog decided to look at Alcoa, much of its operation would have to shut down. It was the unintended result of legislation written with new projects in mind, not existing ones.
The Government started work on an exemption order to allow Alcoa to keep mining, while assessing a five-year mining plan proposed by the miner.
A detailed Water Corporation assessment damned Alcoa's plan.
> **_"Bauxite mining operations represent the single most significant risk to water quality in Perth"
> "Probability of contamination ... is considered certain."
> "Mining impacts are persistent and irreversible"_**
> Water Corporation 2023 risk assessment of Alcoa's 2023-2027 mine plan
The Department of Water and Environmental Regulation (DWER) did not endorse the plan.
> **_"There is likely a high level of risk to public drinking water"
> "Could render water from the (Serpentine) Reservoir unusable for a period of weeks, months or, in extreme circumstances, years."_
> _DWER 54-page Overview_**
The Water Corporation board was told that its past advice to protect water quality no longer had Government support, "recognising that JTSI (now the Department of Energy and Economic Diversification) and DWER had formal instructions to have no impact on social or economic factors."
In other words, under Cook it was jobs for thousands before water for millions, the opposite of McGowan's stance.
****Almost all of Alcoa's mining occurs in water catchments. Exploration planned in the previously untouched Harris, Canning, and Mundaring catchments is temporarily on hold****. __Image: Water Corporation submission to EPA.__
## Lower standards, higher risk
The Water Corporation board was told the Government required "a relaxation in the existing conditions on Alcoa ... allowing Alcoa to mine over a larger area and without almost any constraints outside 1km of the high water mark of the dams."
The "existing conditions" imposed on Alcoa in previous mining plans stopped Alcoa mining near dams, on steep slopes, or near groundwater and limited how much of a valley (or sub catchment) could be cleared.
A later briefing discussed the Corporation's push to "influence the reinstatment of historic constraints to mining."
In contrast to Water Corporation's talk of existing conditions being relaxed and working to have them reinstated, an Alcoa spokesman said: "there has been no reduction in controls related to water protection applied to our operations."
"Alcoa has not had a negative impact on WA’s drinking water supply since operations commenced," he said.
Alcoa lied about jarrah forest rehabilitation: ad watchdogThe Ad Standards decision has demolished a key plank of the US miner’s expensive campaign to win public support for expanded mining in WA.Boiling ColdPeter Milne
## Jobs threat - empty or real?
In December 2023, Cook's Government approved Alcoa's mining plan and granted it an exemption order that enacted the current lower standards.
It happened days after the US miner told Cook that it was "not economically viable for Alcoa to completely retreat" from "operating in higher risk areas."
The $13 billion company went on to make an $881 million profit in Australia over the next 12 months.
_Boiling Cold_ asked Alcoa whether the large profit showed its WA operations could still have been economically viable with significantly less access to higher-risk areas.
An Alcoa spokesman said in this context economic viability did not mean profitability but the ability to supply sufficient bauxite to keep its alumina refineries operating, "therefore the basis of your question is incorrect."
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## New rules on the way
In June the WA Government announced it would update the current exemption order "in coming weeks."
The move gives the Cook Government an opportunity, if it wants, to reinstate the water supply protections it removed in 2023.
Environment Minister Matthew Swinbourn would not say if the new order would reduce the risk to the water supply, but said its terms and a new Alcoa mining plan remained under active consideration.
Exemption orders are temporary measures until the EPA makes its recommendations to Swinbourn and the Government imposes a new modern regulatory regime onto Alcoa.
The Water Corporation's 2025 submission to the EPA, obtained by a _Boiling Cold_ freedom of information request, calls for the independent watchdog to support the reimposition of the "the four key principles of catchment management" Cook removed.
It may be some time before the EPA reveals if it backs the state-owned utility's consistent calls for Alcoa's mining to be not too close, not too steep, not too much and not too deep.
In February, Alcoa told investors the EPA was likely to make its recommendations by June, with the Environment Minister to hand down his decision by December, but the EPA assessment is still underway.
EPA chair Darren Walsh said the Authority continued to review Alcoa’s responses to the public submissions and was focused on completing its assessment and finalising its report for the Minister.
WA Forest Alliance (WAFA) campaigner Jason Fowler wants the Government to immediately ban Alcoa from Reservoir Protection Zones (RPZs) that extend 2km from the dam water's edge, where strip mining is allowed but much lower impact activites like hiking are forbidden.
The Alcoa spokeman said it would not seek to mine in RPZs when seeking apporval to mine in new areas.
WAFA also wants no new mining in drinking water catchments, and all current mining there to cease by 2028.
"Without these protections, the quality and quantity of drinking water from Perth's water supply dams is at severe risk," Fowler said.
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See the complete set of documents on Alcoa's mining in WA made available by _Boiling Cold._