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.
"We will be calling for a full investigation of this incident, how it came to be, how it has been responded to and how it will be remedied to ensure such incidents are mitigated into the future."
Rameka said local infrastructure failings were becoming all too common of late.
"It is critical for all of us to be very clear about the issue and how we are to move forward to ensure our natural environment is protected and our critical services are safeguarded from failures such as today."
It will reportedly take weeks to clean up the huge discharge of raw sewage into Lake Taupō after a wastewater pipe broke on the lakefront.
The main burst just after 2pm and about an hour later the footpath collapsed and took out a wastewater pipe, causing an unknown quantity of wastewater to enter the lake for up to 1.5 hours.
Taupō mayor David Trewavas told the Herald the amount of wastewater entering the lake was now down to a trickle.
It was devastating this had happened to one of the cleanest lakes in the world but it appeared to be an act of nature, he said.
The wastewater spill today followed nine separate wastewater spills into Lake Taupō between January 2017 and January 2018, most caused by inappropriate materials such as fat and wet wipes being flushed into the wastewater system, which blocked pipes and caused wastewater to overflow into the stormwater system.
The Taupō District Council mounted an intensive public education campaign and also stepped up its programme of using CCTV to inspect pipes, flushing them with high-pressure water and replacing pipework. The last wastewater spill was 18 months ago.