A post-mortem examination will also be conducted.
The discovery of the body prompted police to contact the mother of a man who has been missing for nearly a year.
The mother of Joel Linwood, who was last seen fleeing towards the then-flooded river following a truck crash in July 2021, was notified by police about the body, Stuff reported.
Two other passengers were in the vehicle at the time and sustained injuries.
Linwood was wanted by police at the time of the crash for cutting off his electronic monitoring bracelet.
But his family has maintained he was not on the run.
