Green Party co-leader Metiria Turei says Maori should have the right to be decision-makers over rivers which flow through their rohe.
She was part of a discussion in Parliament on Thursday on a bill which formalises the relationship between the Maniapoto iwi and the Waipa River, which is the largest tributary of the Waikato River.
Mrs Turei says over time the river has been severely degraded due to sewage and farm waste pouring into it, as well as stop banks being developed.
She says that's all happened contrary to the wishes of hapu and iwi.
Mrs Turei says an issue which arises again and again for iwi is the extent to which they are separated from environmental decisions which regional councils make.
She says that's something the Green Party will fight to change.