Tūwharetoa Māori Trust Board chief executive Topia Rameka said it was "very disturbing" to hear of the major spill into Lake Taupō.
He said the board would be calling for a full investigation.
He understood the Taupō District Council and its contractors were doing a thorough clean-up operation.
"We will be keeping in close contact with council while that operation is in progress," Rameka said.
"While this incident is still unravelling, our immediate concerns are for the health and wellbeing of our local communities and our taonga - Lake Taupō and the Waikato River.