Landowners and businesses operating downstream of Huka Falls are advised to be cautious of the river water after it was polluted by a brown substance.
Reports suggest a wall of a holding pond failed this morning and its contents entered a tributary which leads into the Waikato River upstream from the falls.
Taupō-based Waikato Regional Council staff have collected samples from the water for testing this afternoon and incident response staff are on the scene.
Patrick Boyle said he headed to the river to go for a swim today when he spotted the murky brown substance in the river.
He posted a video to Facebook and messaged the council who told him it was an issue with the Centennial Drive water treatment plant intake, he said.
In a statement, Contact Energy said it was investigating a slip which flowed into a small stream which feeds the Waikato River, causing the discolouration.
The slip occurred following an "incident" at Contact Energy's Wairakei geothermal operations earlier today.
"We are working with the local councils to assess the impact of this," Contact Energy's head of generation geothermal operations John Clark said.
"We are conducting precautionary tests on the water and are working with stakeholders in the Wairakei area to ensure they are informed."
The water flow was contained this afternoon and the muddy water is expected to clear quickly.
"Taupō District Council has shut off its Centennial Dr water supply intake and is asking users of that scheme to conserve water," Waikato Regional Council said.
"The scheme supplies Centennial Dr and Rakaunui Rd users, as well as the local golf club and the pool at the Top Ten Holiday Park."
"The district council has also cut supply of raw water to Owen Delaney Park, AC Baths, Tenon and Laminex in the interests of conserving water."
The district council is working on providing an alternative treated water supply from the Taupō town scheme.