Two First Nations in northeast B.C. have started legal action against the Site C dam, claiming its construction violates Treaty No. 8 signed 1899, as well as the Canadian Constitution.

In notices of civil claim filed Jan. 15, the West Moberly and Prophet River First Nations say the mega-project will infringe on their treaty rights and "fails to uphold the Honour of the Crown."

The Nations also seek an injunction to prevent any future construction at Site C on the Peace River, seven km southwest of Fort St. John, B.C.

BC Hydro, the Attorney General of Canada and the province are named as defendants and have 21 days to file a response.

Part of the Peace River valley scheduled to be flooded in order to build the Site C dam in northeastern British Columbia. (Justin McElroy/CBC)

This new legal action will allow the courts to decide whether Site C does, in fact, violate treaty rights of the Prophet River and West Moberly First Nations.

The Federal Court of Appeal previously dismissed a lawsuit from the two First Nations that sought to halt construction of the dam. But the panel of judges did not rule on whether the hydroelectric dam violates the 1899 Treaty 8 agreement.

Instead, the judges agreed with lawyers for BC Hydro and Ottawa who argued government should be allowed to issue permits for projects like Site C without first discovering if they violate treaty rights because elected officials do not have the legal expertise to make that determination.

McLeod Lake Indian Band Chief Harley Chingee says jobs on Site C construction are helping band members economically. (Christer Waara/CBC)

The two Nations have previously said they believe Site C constitutes a $1 billion treaty violation, a figure based on the amount awarded to the Cree and Inuit of northern Quebec after they went to court to stop the construction of the James Bay Project in the 1970s, paving the way for modern-day land settlements.

In December, B.C. Premier John Horgan announced his NDP government would complete the project started by the previous Liberal government, calling it a "difficult decision."

Five First Nations have signed benefits agreements with BC Hydro for Site C to go forward, but only the McLeod Lake Indian Band has spoken publicly in favour of the project, with Chief Harley Chingee saying the approval was a "Christmas present."

BC Hydro says the project is on track to be completed by 2024. It is estimated the dam will flood 5,500 hectares of the Peace River valley and provide energy to power the equivalent of around 450,000 homes each year.