A Maori hapu from Northland is considering appealing against an Environment Court decision which clears the way for 200 underwater turbines to be built in Kaipara Harbour.
Crest Energy wants to build a 200-megawatt station, the world's largest tidal power scheme to provide electricity to all homes and businesses north of Albany in Auckland.
Te Uri o Hau, the kaitiaki (guardians) of Kaipara Harbour, say it is home to New Zealand's largest estuarine ecosystem and they are concerned about the turbines' effects on snapper and other marine life.
A study by the National Institute of Water and Atmospheric Research shows 98% of all North Island west coast snapper originate from the harbour.
The Environment Court says the hapu's concerns are important but other issues outweigh them.
It has recommended the project be given consents by the Minister of Conservation, but says the company should be allowed to install only three turbines instead of 20 in its first stage.
It is also recommending that there should be increased monitoring of the environmental effects.
Crest Energy says research from independent experts says the turbines will not cause any damage. Director Anthony Hopkins says he believes the right conditions are now in place.
Northland Regional Council chairman Craig Brown says he is happy the project is progressing and it will provide a reliable energy supply in the region.
Parts of the consent and its conditions will now go to the Conservation Minister for approval.