Soil and sediment that leaves properties on the Port Hills ends up on footpaths, gutters and roads. This feeds into Cashmere stream and Heathcote/Opawaho river.
The soil increases the likelihood of the waterways flooding, smoothers habitat for fish, and impedes the flow.
Waihoro-Spreydon-Cashmere Community Board member Lee Sampson said preventing soil from going into the stream was important.
The Christchurch City Council is planning small dams, settlement areas and light planting in areas where water starts to run from down the hills to help prevent soil being fed into the stream.
But Sampson said residents needed to do their bit.
"Anybody who lives on the hills can make small improvements to stop pollution going onto the streets and into the stream," he said.
"The soil is so fine that it strangles the river to a degree. The council is currently installing settlement basins next to the adventure park. There are works in progress but we still need to do a heap more," Sampson said.
People needed to be careful about chemicals used to clean cars, fertilisers and water use.