The mayor of the Kaipara district is to lead an 11th hour bid to block a tidal power station in the harbour.
Crest Energy has consent to place three large turbines in the harbour mouth.
A public meeting in Dargaville on Monday night voted to fight on after Maori hapu Te Uri o Hau lost a court bid to stop the tidal power station.
Mayor Neil Tiller told the meeting he is opposed because the technology is largely untried and there is a risk to marine life and the harbour.
South Kaipara people are planning similar public meetings.
The final decision rests with Conservation Minister Kate Wilkinson.