Alcoa’s proposal to expand its strip mining of forest near Perth’s dams poses a significant threat to the water supply for the city’s 2.3 million residents, according to a study by global engineering consultancy GHD. Alcoa, a US aluminum producer, commissioned the detailed analysis as part of its bid for approval to mine an additional 67 sq km of jarrah forest for bauxite, the material used to produce aluminum.
The study reveals that Alcoa’s mining threatens the water supply through three main pathways: contamination from pathogens and sewage, oil spills from its mining operations, or excessive soil running into the dams, which could render water treatment plants ineffective. GHD identified 22 pathways for contamination and concluded that all but one of them presents a high risk.
Alcoa’s history of wholesale forest clearing and inadequate rehabilitation after mining has increased the open area at risk of significant runoff. Additionally, its preventive drainage works have a history of frequent failures. The company has been mining the jarrah forest without regular environmental oversight, thanks to a legislated agreement with the state.
The WA Forest Alliance, an environmental advocacy group, is calling for an immediate ban on mining in reservoir protection zones and a complete phase-out of mining in water catchments over the next few years. The group argues that this will protect critical drinking water supplies for Western Australia and provide a strong habitat for endangered plants and animals.
A similar study by the UN Intergovernmental Panel on Climate Change warns that the highly biodiverse northern jarrah forest ecosystem is at risk of collapse due to hotter and drier conditions, with a higher frequency of fires.
Alcoa extracts three-quarters of its global bauxite production from the jarrah forest and has been responsible for the clearing of 280 sq km of forest since 1963. The company currently mines without having completed the rehabilitation of a single hectare of land.
WA’s Environmental Protection Authority will assess both Alcoa’s current mining and its proposed expansion after public comments on its plans are submitted. The EPA’s assessment will determine the conditions under which Alcoa’s mining will be allowed based on social, economic, and environmental factors.
Source: https://www.theguardian.com/australia-news/2025/aug/20/perth-water-supply-risk-alcoa-bauxite-mining
