Over the last eight months, Turangi residents have watched these Tongariro River banks near the Kohineheke Reserve slip away.
Denis Greenslade fishes on the riverbed often. He has been monitoring the banks - and says over the last six to twelve months the bank has eroded "seven or eight meters."
"What's happening is the pressure is coming from this southern bank and it's just undermining this area completely, the area across here used to be relatively straight."
And it's a concern because where the erosion is occurring is commonly used by anglers, visitors, and locals - on foot and in vehicles.
"It's now got to the stage where it's doing a lot of damage further down the river to the fishery - all the sediment is settling further down and filling what were natural holes for the fish, and it's presenting a health and safety issue," Mr Greenslade says.