He said the option to transfer some functions to iwi has been available to councils for 30 years but it has never happened until now.
The council has approved the transfer of functions that include the weekly collection of water samples at five bathing beach sites on Lake Taupō during the summer, monthly assessment of water quality at 12 rivers that are tributaries into the lake, rainfall monitoring and groundwater monitoring.
Tūwharetoa will use the same tools and methods as those utilised by council monitoring staff.
Williams said the change will bring cost-savings to the council and make the work more efficient, as it will be carried out by local people.
He said the change also recognises Ngāti Tūwharetoa's ancestral relationship with Lake Taupō and its tributaries.
Williams said further transfers of functions cannot be ruled out in the future.
"It is very complex to do and from a council's perspective there are many hurdles to get through.
"It requires a real dedicated focus and genuine desire to work collectively and collaboratively together to get to achieve a beneficial outcome."
Williams said he hopes other iwi are closely watching what has been achieved between the Tūwharetoa Māori Trust Board and Waikato Regional Council.
"This is an appropriate process for any iwi which has the right intention and is prepared to work constructively to identify an effective solution to primarily environmental-related opportunities.
"And for iwi it is about their mana motuhake, their desire to be in control of the things they believe are important to them and they have a natural right to do."
- RNZ
