“I have had no one come to me and say you need to shut down their operations at this point in time, what I have had is advice that says for new mines, you need to make sure that the that all of the risks are appropriately managed and that’s what we’ll do.”

The internal government advice explicitly stated that for the past two years government experts had been warning Alcoa that the risk of sediment flow to dams had increased rapidly.

The advisers feared this was due to Alcoa’s movement into higher-slope regions of the catchment area, larger pit sizes, and increases in unrehabilitated areas, which was compounded by a lack of science to inform decision-making.

It warned that a severe event such as a fire followed by a heavy rainfall event could result in huge amounts of pathogens and chemical-carrying sediment flowing into the dam that would leave it offline, potentially for years.

In addition to the current risk to the dam, the advisers said Alcoa’s proposed mining plan for the next five years represented even more risk.

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Despite government experts being across the issue for two years, McGowan said he only became aware of it late last year ahead of a meeting with Alcoa’s global chief executive Roy Harvey.

Environment Minister Reece Whitby, State Development Minister Roger Cook and former Water Minister Dave Kelly also met with Alcoa on December 15 last year to discuss the dam issues.

In Cook’s September 2022 approval of Alcoa’s 2022-2026 mining plan he issued the company with a list of 12 expectations the company had to meet ahead of the approval of its 2023-27 plan.

A state government spokeswoman said the premier and senior ministers had met with Alcoa and made clear to the company that water risks needed to be appropriately managed.

An Alcoa spokeswoman yesterday defended the company’s mining operations in WA, saying they had never impacted drinking water supply, and Alcoa took its environmental obligations seriously.

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