Rangitīkei District Council has been granted resource consent to divert part of the Rangitikei River away from the old Putorino landfill, which has been leaking rubbish into the water.
Residents raised the alarm with council late last year after finding rubbish in the river.
Chief executive Ross McNeil said the Rangitikei River had changed its course and subsequently eroded the bank on one side of the landfill site during a period of high flow.
The Putorino landfill was established under the former Rangitīkei County Council and is believed to date back to the 1970s.
At that time the river bank would have been well back from the edge of the landfill.
Mr McNeil said Horizons Regional Council - which issued the consent to divert - will carry out the work of redirecting the river channel away from the landfill.
"Once the river flow below the landfill has been moved, we will be able to undertake the assessment work required to determine the best options for dealing with the old landfill," McNeil said.
He said that could likely involved engineering work to protect the landfill area from future river erosion and removing the contents of the landfill.
"We're committed to resolving this issue as soon as possible.
"Once the river is diverted, Horizons and Rangitīkei District Council will collectively look at a permanent solution, as a separate consent to undertake the required remediation work may be required.
"At this stage we're not sure how long the job will take or what the cost will be."