Waikato Regional Council is urging people to treat bright orange discolouration of the Ohinemuri River as contaminated.

Senior Incident Response Officer Robert Isaac says worst case scenario is the discoloured water is due to a mine shaft collapse, and old mines contain many heavy metals and contaminants.

The incident was reported to the council at about 3pm.

Council staff are at the river and are assessing the discoloration.

Isaac says staff have yet to identify the source of the discolouration, which appears to enter the Ohinemuri River downstream of the Waitawheta river.

“Until we can ID the source we need to treat this as worst case scenario as we are getting reports of people standing in the water. If this is an old mine shaft that has blown out than people should not be using or touching the water.”

Other scenarios could include a collapsed forestry dam or other erosion.

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