Environmental group Forest and Bird says a decision not to allow a dam to be built on the Nevis River in Central Otago is a victory for wild river protection.
The dam had been proposed by electricity company Pioneer Energy.
A special tribunal set up by the Ministry for the Environment has prohibited any dams being built on the river, to protect a distinct local population of native fish.
Forest and Bird conservation advocate Quentin Duthie says the decision is a win for biodiversity.
He says the next battle for conservationists will be over the fate of the Mokihinui River on the West Coast where a dam project is also proposed.