Maori groups have made emotional submissions to the Waitangi Tribunal hearing into water rights.
Claimants want ownership and management issues settled by the Crown before the partial sale of selected state-owned assets.
The Mixed Ownership Model Bill passed in Parliament by 61 votes to 60 on 26 June this year. The legislation opens the door for the sale of up to 49% of shares in Genesis Energy, Meridian Energy, Mighty River Power and Solid Energy.
The tribunal began urgent hearings at Waiwhetu Marae in Lower Hutt on Monday on water claims the Maori Council hopes will delay the Government's plans to sell asset shares.
The council believes that iwi and hapu will lose any right to water ownership when the Government sells stakes in the selected SOEs and argues it should delay offering the shares until historical claims have been resolved.
About 200 people attended the hearing on Monday, where at least 10 claimants are making submissions.
The Whatitiri Maori Reserve Trust represents three hapu in Northland and told the hearing it turned to the tribunal because it is not being listened to elsewhere.
The trust's Meryl Taimania Carter says Maori no longer want to be just a fly on the wall when it comes to the management of Poroti Springs, which partly supplies Whangarei.
"We do manage a lot of it, but we want to be recognised as the managers of it. We do do the work on that waterway - and yet when it comes to dishing out consents and how long they're going to be given for, we have no say at all."
The trust says spring water west of Whangarei is being used to wash down cowsheds and is being wasted.
Another claimant, a Rotorua hapu, told tribunal members water is not like land; it has its own mana.
Kaitiaki, or guardians of Kaituna River, told the hearing the river was full of eels or tuna before New Zealand was colonised, but that stocks have dropped dramatically over the years as Maori do not have a say in how water in the river is controlled and managed.
They want to have a say in who goes on the river and how much water is extracted before any private investors are able to use the water by buying shares in power generation.
Another group told the hearing that adventure tourism makes money from using rivers, but Maori do not receive any benefit.
Sir Graham Latimer, who brought the claim on behalf of the Maori Council, is too frail to give evidence and watched proceedings from his wheelchair on Monday sitting next to veteran activist Titewhai Harawira and her son Mana Party leader Hone Harawira.
The hearing is expected to continue into next week.
PM says no one owns water
The Prime Minister does not think there is merit in the Maori Council's water claim before the Waitangi Tribunal and its findings are not binding on the Government.
John Key acknowledges that the council could potentially take legal action. However, he says there is no basis to the claim that Maori own the water and the Government would vigourously argue its case if it ends up in the High Court.
"The Government's very strong view is that no one owns water, in the same way that we don't believe anyone owns the air or the sea.
"We think people certainly have water rights, but the fact that the Government is looking to sell 49 percent of Mighty River Power in our view doesn't alter those water rights at all."
Mr Key says the Government is dealing with water rights issues through other mechanisms, including the Land and Water Forum.
The Green Party on Monday criticised Mr Key for what it describes as glib comments about the hearing. Treaty spokesperson David Clendon says he has shown disrespect for the Waitangi Tribunal.
Labour Party leader David Shearer says National did not think through the effect of Treaty of Waitangi claims on partial asset sales before launching its plans.
Mr Shearer says the tribunal hearing and any subsequent court action will worry the Government. He says compensation may have to be paid if claims are successful - and that will be costly for taxpayers.
Maori Party co-leader Pita Sharples says the hearing is hugely important, as evidence is presented about water management.
