Two major iwi are welcoming the passing of the first of three controversial Three Waters bills

Waikato-Tainui's Te Arataura Chairman Tukoroirangi Morgan is calling it a watershed moment for New Zealand -- and particularly their tribal members.

He says The Water Services Entity Bill gives iwi a once-in-lifetime opportunity to be at the decision-making table.

Morgan says 75 percent of Auckland's water comes from the Waikato River and the Hunua Dams -- waterways firmly located in their tribal territory.

Meanwhile, Ngai Tahu also looked forward to working more closely with local councils.

Te Runanga o Ngai Tahu Kaiwhakahaere Lisa Tumahai says the legislation allows iwi to share their expertise in governance and traditional knowledge.