Upstream the iwi has also planted on private and Whanganui District Council land adjoining SH3 and William Birch Pool.
Haare Tapiki began Friday's planting with a karakia, before Ngā Rauru kaiwhakahaere Anne-Marie Broughton told the group the land was in the rohe (area) of Ngāti Maiki, based at Pakaraka Marae.
Plants used were hardy coastal trees and shrubs - ngaio, tree daisies and cabbage trees, with harakeke (flax) and purei to filter water. Shading the stream will cool the water for native fish.
The popularity of remote Ototoka Beach is increasing, and children love paddling in its stream. But the stream only met swimming standards four per cent of the 2017-18 summer season, Horizons Regional Council monitoring showed.
It was high in the faecal coliform bacteria E.coli, an indicator that disease-causing organisms may be present. Most of the 29sq km catchment is sheep and beef and dairy farms, and 50 to 100 per cent of the bacteria were from sheep and cattle - mainly cattle.
Horizons is offering 50 per cent subsidies for landowners wishing to fence and plant the stream. Horizons councillor David Cotton hopes to have an Ototoka catchment care group started by Christmas, and will invite Ngā Rauru.
He favours using key people to influence their farming peers in a "rifle" rather than "shotgun" approach - "one bullet looking at one bullseye".
Fellow councillor Nicola Patrick was on an Ototoka field trip initiated by Ngā Rauru in February. She saw some really good practice, as well as places where stock need to be kept out of the water.
She said a lot more work needs to be done upstream - but with such a small catchment it should be possible to exclude stock from the whole stream.
Lessee John Scott agreed that most of what needs to be done is upstream. He said Friday's planting was mainly cosmetic - but still very worthwhile.
There's a lot more to do, Shaw said. She would like her iwi to have a freshwater management plan for its rohe.
And the planting project is consistent with Ngā Rauru's Kaitahi superfoods business, manager Leonie Matoe said.
The push was toward "more forest-based kind of planting, diversification on farms, crops of puha and kawakawa." It was about healing land, water and people - "attacking it from all angles," she said.
Whanganui senior stormwater engineer Kritzo Venter was there, spade in hand, as part of the Healthy Streams Whanganui project.
"It's good to see a lot of different backgrounds coming together to do this," he said.
