Water inspectors shut out of Alcoa mine sites in Perth drinking water catchment, documents show

Fencing installed around Alcoa’s bauxite mine sites in 2025 blocked rangers conducting inspections, Water Corporation documents say

Conservation groups have accused the US mining company Alcoa of blocking scrutiny of the effects of its mining operations on Perth’s drinking water after new documents revealed catchment inspectors were shut out of its sites.

Briefing documents for the Water Corporation board also show the utility was frustrated that the Western Australian government had stopped giving it information about Alcoa’s mining plans, making it harder to manage potential threats.

The WA Forest Alliance, which obtained the records under state freedom of information laws, claimed the “lack of oversight is alarming” and called on the Cook government to “ensure full access to monitor Alcoa’s activities”.

Alcoa’s bauxite mining operations in WA’s northern jarrah forests span 12 public drinking water catchments that require regular monitoring.

A study by the engineering consultancy GHD found the mining company’s expansion plans posed a high risk to the water supply for Perth’s 2.3 million people.

An Alcoa spokesperson said: “In more than 60 years of operation we’ve never negatively impacted Perth’s drinking water.” They added the company was committed to the protection of drinking water supplies.

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The documents show Water Corporation raised concerns throughout 2025 that new fencing Alcoa had installed around its mine sites was preventing water monitoring.

The fences had shut out rangers who needed to inspect the catchment and staff were having to obtain new work, health and safety training and vehicle modifications “to reinstate mine site access”, the corporation wrote in February last year.

Six months later, Water Corporation inspectors still had concerns and the corporation raised “the issues we are experiencing gaining site access for our rangers to conduct inspections in the catchment” with Alcoa executives.

The WA Forest Alliance said the limitations on access were troubling because “these inspections are critical to ensure safety of drinking water for hundreds of thousands of Western Australians”.

A Water Corporation spokesperson told Guardian Australia: “We have been forthright in engaging with Alcoa to remedy previous concerns over site access and to ensure data is shared in a timely and comprehensive way”.

“We continue to thoroughly monitor all mining activity in proximity to public drinking water catchments.”

In further documents released under FoI, Water Corporation said that due to a restructure of the way advice is provided to government about Alcoa they no longer received the company’s mining plans.

Water Corporation is on an independent technical advisory group but is not on a new strategic bauxite committee. In the released documents, Water Corporation said that change had “constrained our ability to plan risk mitigation activities”.

The corporation wrote that the energy and economic diversification department had stopped providing it with Alcoa’s mining plans, which it said was “preventing the Water Corporation from being able to plan risk mitigation controls”, and the department responsible for water and environment regulation was “declining” its offers of direct technical advice. In responses to Guardian Australia, both departments said they worked closely with other agencies, including Water Corporation.

The documents said that when Water Corporation did gain access to the mining management plans, via the state health department, it found they “are not considered sufficient to reasonably assess the potential impacts” of future mining operations on the water supply.

However, in response to questions, both Water Corporation’s spokesperson and the state government said the water supplier could still provide advice via the technical advisory group.

“Water Corporation frequently provides robust and high-quality advice to government on Alcoa’s operations as a member of the Independent Technical Advisory Group,” a government spokesperson said.

Alcoa’s spokesperson said “we continue to strengthen our relationship with Water Corporation” and the company had processes to “enable visibility of our current and planned mining activities and Water Corporation’s ability to monitor water quality”.

“These include data sharing, participation in the government’s Independent Technical Advisory Group (ITAG) and site visits,” they said.

Jason Fowler, senior campaigner at the WA Forest Alliance, said the WA government should “urgently heed the utility’s advice on managing the threat to drinking water, and ensure full access to monitor Alcoa’s activities”.

“Water Corporation are the experts on preventing contamination of drinking water dams,” he said. “If they can’t relay that information directly to decision makers, it’s a huge concern.”