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Story: Geothermal energy

Arsenic in the Waikato River

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Arsenic in the Waikato River

The winding band on this map marks the course of the Waikato River, and its width represents the water’s arsenic content in the period 2000–2004: the wider the band, the more arsenic there is. Arsenic is toxic, and water for human consumption should contain less than 0.01 parts per million (ppm). This is exceeded over most of the course of the river.

Most of the arsenic in the Waikato River comes from waste fluid from the Wairākei geothermal power station. Water treatment at Hamilton removes 80%, leaving the city’s water safe to drink.

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Te Ara - The Encyclopedia of New Zealand

Source: Environment Waikato

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How to cite this page

Carol Stewart, Geothermal energy – Effects on the environment, Te Ara – the Encyclopedia of New Zealand, https://teara.govt.nz/en/map/5439/arsenic-in-the-waikato-river (accessed 4 June 2026).

Story by Carol Stewart, published 2 March 2009.