The Canterbury Regional Council hopes pumping river water into Ashburton's groundwater system will reduce nitrate levels in it.
Under a pilot project beginning next month, about 500 litres a second will be taken from the Rangitata River and pumped into the ground.
Together with on-farm nutrient management, the aim is to reduce nitrate leaching into groundwater by 36 percent by 2035.
If successful, the idea could be extended to a wider area.
