Waiwhakaiho River clearing

8 November 2013

The Waiwhakaiho River is clearing but is still slightly turbid and discoloured. Yesterday the upper reaches of the river flowed orange.

The Taranaki Regional Council has identified the source of the discoloration in the headwaters of the Kokowai Stream which is a tributary of the Waiwhakaiho River near the Boomerang slip on Mount Taranaki. The name Kokowai means ‘red ochre’.

“The Kokowai Stream was flowing bright orange yesterday when we flew over the area and there appears to have been a significant rust-coloured flow of water and sediment at the source of the stream,” says the Council’s Compliance Manager, Bruce Pope.

“Iron is a common element in Taranaki’s water and volcanic rock and soils, and rust-coloured deposits or cloudy orange water often occur naturally in Taranaki waterways. The iron reacts with atmospheric oxygen or dissolved oxygen in surface water to form rust-coloured iron oxide which precipitates out and can also give a waterway a cloudy appearance.

“These sort of events are sometimes mistaken as pollution events when they are sighted in the lower reaches of our waterways. Iron oxide deposits occur naturally and although unsightly, are not toxic to fish or other aquatic life. They are not an environmental health risk.”

Mr Pope says the Waiwhakaiho is a fast flowing catchment and expects it to continue to clear over the next few days unless another large volume of material enters the river.

The Taranaki Regional Council is working with the New Plymouth District Council to monitor the Waiwhakaiho River and to check water quality.

ENDS

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