Whanganui District Council has nominated former two-term mayor Annette Main as the local authority's representative on Te Karewao.
Te Karewao is an advisory group to Te Pou Tupua - the two people who will act and speak on behalf of the legal personhood of the Whanganui River, known as Te Awa Tupua.
In September, former government minister and Maori Party co-leader Dame Tariana Turia and Turama Hawira, a trustee and director of several hapu and iwi trusts and organisations, were appointed to the office of Te Pou Tupua, as position described as "guardians of the river" following the Whanganui River Treaty settlement.
Dame Tariana and Mr Hawira were inaugurated as Te Pou Tupua at a pre-dawn ceremony in Taumarunui on Saturday.
Ms Main is a former Horizons regional councillor and current member of Whanganui District Health Board.