Mighty River Power and Ngati Tuwharetoa have reached a deal over the use of Lake Taupo's water.
The central North Island tribe owns the lakebed and has the legal right to charge commercial users.
The power generator takes water from Lake Taupo, which then flows down to its hydro schemes.
A Mighty River Power spokesperson said Lake Taupo fed its Waikato hydro system, which accounted for 10 percent of the country's electricity supply.
Negotiations over payments for storing water accelerated when the Government decided to sell almost half of Mighty River Power to private investors.
The financial arrangement is not being revealed but Tuwharetoa has previously told Radio New Zealand it wanted to charge Mighty River Power several million dollars a year.
The iwi said it had estimated it had missed out on $1.75 billion over the years.
The new commercial agreement will run for 52 years, and Tuwharetoa Maori Trust Board chair John Bishara said nothing would change for the lake's recreational users.
"This positive outcome reflects the mana Tuwharetoa holds as owners of the Lake Taupo lakebed and we look forward to working further with Mighty River Power," he said.
Mighty River Power chief executive Fraser Whineray said the company acknowledged Tuwharetoa as owners of the lakebed, and their role as responsible stewards and business leaders in the community.
"We appreciate that Lake Taupo is very important to Tuwharetoa and we are pleased to have been able to reach this partnership agreement, which strengthens our relationship," he said.