Ngā Tāngata Tiaki must become an integral part of the community - "not just those Māori over there" - general manager Blair Anderson says.
He was appointed to the position in May, and said the trust was still very much in start-up mode.
The innovative Whanganui River Settlement passed into law in March and the trust is its governance entity.
Mr Anderson wants his team to meet the expectations of the old people who toiled for more than a century to assert their connection to the Whanganui River.
"I'm accountable to them, and much, much more. Failure isn't an option," he said.
The trust's aim of health and well-being for the river and its people are what he has "lived and breathed" all his life.
"It's how do we shape that into an actual activity. What the legislation doesn't tell you is how to get there."
The gist is "how we best live and engage with our environment", he said.
The settlement makes the river a legal being with rights and responsibilities, and two people who will speak for it. It's such a new concept the trust is getting international requests to talk about it. Chairman Gerrard Albert is responding to most of those.
People are also asking the trust whether they can continue their activities on the river.
"We encourage them to do what they have always done. Ours is to ensure that once that activity is done that there's no negative impact from it," Mr Anderson said.
And the trust is keeping an eye on river changes such as port revitalisation and repair of structures. It will provide independent administrative support for Tariana Turia and Turama Hawira, in their roles representing river interests.
River health is affected by deforestation, erosion and silt build-up. It's also affected by headwaters diversion, with that water used by Genesis to generate electricity.
It will be 20 years before consent for the diversions expires. Mr Anderson said that should be an interesting process, because the iwi would never agree to those diversions.
He doesn't know how the trust will relate to any governance entity established after Whanganui's land claims are settled.
"Nobody is quite sure, because as we can already see, Tupoho has its economic arm operational. It will be for the people to decide. We will just be prepared to respond."
Mr Anderson has kinship links with Te Atihaunui a Pāpārangi, with Ngā Rauru, Ngāti Rangi and other iwi. He's heading up a staff of seven - four project managers, a strategic adviser and two administrators.
He's had a 30-year career in the public service, with bodies such as Māori Affairs, the Department of Internal Affairs and Te Puni Kōkiri. Most recently he was the manager of the Māori Land Court's Aotea District, the Justice Ministry's best-performing office.
That job meant a lot of travel.
"I'm getting too old for that stuff. I decided I needed to focus more at home. This role gave me the opportunity to do that," he said.