The so-called "People's Beach" in Awaroa is in trouble, according to a Massey University ecologist.
The beach was bought by the public in 2016 after $2 million was raised to save it from private ownership.
It was then donated to the Department of Conservation.
Ecologist Steve Trewick told Mike Hosking quad bikes are being used by commercial groups to ferry visitors to the beach, which is ruining its pristine condition.
He says it's a small beach and quad bikes are totally unnecessary.