A North Island hapu is putting its case to the Supreme Court on Tuesday seeking ownership of a section of riverbed near Tokoroa.
Pouakani is claiming ownership of a 32km portion of the Waikato River which contains three hydro dams.
The sub-tribe says, ultimately, it would plan to charge energy companies for using the water but it will first need to secure a ruling from the Supreme Court that the portion of riverbed legally belongs to the people of Pouakani.
Chair of the hapu Tamati Cairns said he has told descendants to take the case in stages.
He said the start point is to declare the descendants the owners of the hydro dams, by virtue of the dams sitting on Maori land.
Mr Cairns said the Government has refused to discuss its contemporaryclaims to the Waikato River and considers that the Crown is ignoring the hapu in favour of pushing ahead with partial privatisation of state-owned power stations in its rohe or district.
Pouakani signed a Treaty settlement with the Crown more than a decade ago, but the door was left open for both parties to continue discussing claims to the Waikato River.