DOCUMENTS obtained by the WA Forest Alliance (WAFA) under Freedom of Information (FOI) reveal that Alcoa’s newest mine site changes have made it challenging for Water Corporation inspectors to supervise impacts to drinking water.

The documents show Water Corporation inspectors faced restrictions after Alcoa installed fencing around mine sites in state forests and banned drone use near mining areas, limiting ability to monitor water quality near key areas including Serpentine Dam.

Water Corporation has acknowledged the issues while defending its oversight role.

A spokesperson said the utility continues to work with all stakeholders in the interest of protecting public drinking water sources and has 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.

The corporation provides independent advice to government through the independent technical advisory group under the Alcoa transitional assessment framework, which it describes as “the established mechanism through which agencies share information and consider risks”.

Water Corporation said protecting drinking water at its source provided the strongest protection for public water supplies.

The state government has a $100 million financial guarantee from Alcoa as a contingency against any impact to drinking water sources.