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."