The Maori trustees of Northland's Poroti Springs are warning they can't guarantee the safety or security of a water-bottling plant to be built there.
Auckland company Zodiac Holdings has the right to take water from aquifers above the springs for 35 years and is looking for investors to build a factory.
But the trustees' chair, Taipari Munro, said local hapu were angry their opposition to the proposal had been ignored, and there have been growing calls for protest and occupation.
"It's not just the young people, you know, who are wanting to see some action taken," he said.
"They're not only the people from Poriti; they're also people who are geneologically connected from other tribes.
"I do feel as the rangatira of those hapu that I can only do so much but I do understand my people's frustrations."
He said local hapu were prepared to take direct action as they had no faith in assurances a water-bottling plant would not reduce the flow to the springs or pollute them.