The McDougals, other landowners, pupils of Kai Iwi School and Horizons Regional Council are all working to improve the Mowhanau Stream.
Yesterday about 20 children were at a point near SH3 and got 500 native plants into the ground in just over an hour, Horizons freshwater co-ordinator Clare Ridler said.
The stream has one of the highest bacterial counts in the Whanganui District, and is a favourite of young paddlers at Kai Iwi Beach. Most of the faecal bacteria have been traced to cattle, but a few to humans.
The McDougals' sheep and beef farm borders about 2km of the main channel, and yesterday's was the second planting Kai Iwi kids have done along it. Ms Ridler said other landowners had also done an impressive amount of fencing on its banks. Yesterday's planting was of trees on the fenced stream banks, with flax and toetoe at the edge of the water. The children, aged 10 to 13, enjoyed themselves and didn't need much encouragement.
As an Enviroschool they have done similar projects at other places.
Asked if anyone fell into the stream, one said "We didn't fall in the water. We went in the water."
Izaac Coe was counting as he worked. He planted 93 plants, and two others planted 80 each.
Ms Ridler said the purpose of the work was twofold - to keep sediment out of the stream and improve water quality, and to make it a better place for fish and water insects. It was working.
"The results are generally improving at the sampling site, likely due to a range of interventions."