Environmental and indigenous groups are cheering a landmark decision by Canada’s highest court on Friday, which ordered the Yukon Territorial Government to abide by a negotiated plan to preserve one of the largest intact wilderness areas in North America.

The Supreme Court of Canada’s unanimous decision marks the end of a three-year legal battle between the Yukon government and a coalition of indigenous First Nations and environmental groups over the future of the Peel Watershed, a wildlife-rich region of mountains and rivers that also has significant deposits of gas, coal, iron, and other minerals. Roughly the size of the Republic of Ireland, the pristine region was featured in an article in the February 2014 issue of National Geographic.

A commission made up of representatives from the First Nations and the Yukon government spent seven years negotiating the fate of the Peel Watershed via a process laid out in land claims agreements signed by Yukon First Nations and the federal and territorial governments. The commission produced a final recommendation in 2011 to keep 80 percent of the watershed roadless and off-limits to resource extractors.

View Images Wildlife are abundant in the Peel Watershed. Photograph by Paul Nicklen

In 2014, though, the Yukon government rejected the commission’s plan and adopted its own mining-friendly version, which would have opened 71 percent of the area to industrial development.

Friday’s ruling chided the Yukon government for disrespecting treaties with First Nations and for contravening its constitutional obligations. The ruling ordered the government to complete final consultations on a land use plan that will protect roughly 80 percent of the watershed.

Yukon: Canada’s Isolated Oasis Learn about the Yukon from the point of view of locals.

Native leaders heralded the ruling and said it will guide the interpretation of modern treaties across Canada.

“This landmark decision sets a precedent that all agreements achieved through modern treaties will be defended and protected by the higher courts in this country,” said National Chief Perry Bellegarde of Canada’s Assembly of First Nations in a statement. “These lands are sacred, and First Nations have the right to be involved in any decisions that affect our lives, our lands, and our waters.

View Images Yukon's former Faro Mine, which is now being remediated, was one of the largest open pit mines in the world. Native tribes had asked the Canadian government to prohibit such mines in the Peel Watershed based on their treaty rights. Photograph by Paul Nicklen, Nat Geo Image Collection

Environmental groups were ebullient. “This is a huge, huge victory for indigenous people and it’s cause for environmental celebration on a global scale,” said Christina Macdonald, Executive Director of the Yukon Conservation Society, which participated in the lawsuits. Macdonald noted that the watershed is the northern anchor of the Yellowstone to Yukon conservation corridor, a multinational conservation region that provides crucial habitats to species threatened by climate change and habitat loss.

“At 68,000 square kilometers [about 26,000 square miles], this area is many times the size of the biggest parks in North America,” said Macdonald. “The plan the government tried to force on Yukoners to open the majority of it for development is finally in the waste basket.”

Tom Clynes wrote the February 2014 National Geographic magazine story on the battle for the Yukon.