The Court of Appeal has heard Forest & Bird's appeal against the High Court approval of the downgrade of conservation land for Hawke's Bay's $900 million Ruataniwha water storage project.
In February the High Court approved a land swap in the Ruahine Forest Park between the Department of Conservation (DoC) and the Hawke's Bay Regional Council, to enable the dam to be built.
DoC is proposing exchanging 22 hectares of protected conservation land in Ruahine Forest Park for 170 hectares of farm land.
It would mean downgrading protected conservation land to stewardship status in order to allow it to be flooded for the dam.
Forest & Bird said the High Court was wrong to allow the land's specially protected status be revoked for a commercial development.
The protected land is home to several threatened species, such as the New Zealand falcon and long-tailed bats.
Forest & Bird's environmental solicitor Sally Gepp said until this case, it was understood that only stewardship land could be disposed of.
"To simply extend it to all specially protected areas throughout New Zealand and say that as long as you want to exchange them, that's a good enough reason to revoke their specially protected status, is a really dangerous precedent that we would be extremely disappointed to see rolled out across the country."
Forest & Bird has said the land swap put into question the protection of nearly one-third of the public conservation estate.