The amount of arsenic in parts of the Waikato River is more than twice internationally recommended safe limits.
Most of the arsenic comes from geothermal waste generated by the Wairakei geothermal power station near Taupo.
For water to be safe to drink, it should contain less than 0.01 grams of arsenic
per cubic metre, according to World Health Organisation standards.
A water report done for Auckland water company Watercare Services put the level at 0.025g per cubic metre downstream of Wairakei.
The water has had such levels since the power station started operating in the 1950s.
Arsenic is a naturally occurring substance in soils near geothermal areas.
It is also a common ingredient in insecticides and herbicides.
Wairakei operator Contact Energy also has consents to develop the Tauhara field.
This could add to the arsenic levels of the river.
- NZPA
Herald Feature: Conservation and Environment
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