Arsenic 133 times above legal level found in Aughinish Alumina groundwater

Groundwater beneath Ireland's Aughinish Alumina refinery is heavily contaminated, with levels of pollutants reaching up to 4,700 times the legal thresholds, according to an investigation by The Irish Times.

Regular testing reports submitted by the Russian-owned company to the Environmental Protection Agency (EPA) show that more than half of the wells and streams on the 530-hectare site, located on the Shannon estuary, contain water exceeding legal limits. This situation has persisted since at least 2021, with some water sources becoming significantly more contaminated in the past year, despite a limited overall improvement in water conditions this year.

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The location of these kinds of industrial sites on karst is really problematic. That is usually something that people try to avoid.

The contaminated groundwater contains high levels of aluminum, chloride, zinc, and sulfate, and is often highly caustic. One observation well recorded aluminum levels 4,735 times the groundwater threshold at the start of this year, and arsenic levels 133 times the legal limit. Geologists note that locating industrial sites on karst, porous limestone rock, is problematic due to water's ability to travel through fissures.

Aughinish Alumina disputes the findings, stating that monitoring under an EPA-approved program shows contaminated water is contained within the facility. The company claims its corrective action plan, agreed with the EPA, is improving groundwater quality. However, the EPA has not taken action against the company for these environmental breaches.

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The conclusion of the most recent annual groundwater review as submitted to the EPA (for 2025) found that overall groundwater quality across the site continued to improve as a result of the corrective action plan.