The Supreme Court has denied an appeal to allow private developers to swap land with the Department of Conservation (DoC) to build a controversial Hawke's Bay dam.
There has been two years of debate over the Ruataniwha dam project. In 2015 the Department of Conservation reclassified 22 hectares of land so it could be used for the project.
The Ruataniwha Dam would help store water for irrigation and improve river flows for the Tukituki Catchment, its advocates say. But its opponents say the dam will flood a significant area of native forest, putting several threatened species at more risk and damage the Tukituki river's water quality.
Forest and Bird's Megan Hubscher had said Thursday's decision could have opened up other parks to similar developments.
"All the forest parks in New Zealand will be affected if this precedent goes ahead. Basically every piece of conservation land except national parks will become available to private interests."
Conservation Minister Maggie Barry said the ruling would give DoC clarity about managing public land.
The Court of Appeal originally said the land swap decision wasn't legal, but the Ms Barry has been trying to change that. Ms Hubscher says it's sending a shocking message.
"The Minister of Conservation, in our view, appears to be advocating for greater private access to publicly owned conservation."