The West Moberly and Prophet River First Nations will seek an injunction against the Site C dam, which received a green-light from the B.C. government Monday.
The project, which will now cost an estimated $10.7 billion, has been vigorously fought by both nations, whose traditional territory will be flooded by the Site C reservoir.
In addition to a court-sponsored injunction, the nations also announced they will pursue a civil case against the project for treaty infringement.