A number of indigenous groups also oppose the project, saying it infringes on the traditional hunting, fishing and trapping rights guaranteed in an 1899 treaty and protected in the Canadian Constitution. While three indigenous groups have signed cooperation agreements with BC Hydro, others remain defiant, saying the dam reservoir would submerge ancient burial grounds, contaminate fish and flood more than 13,000 acres, affecting land they have long relied upon for holding ceremonies, hunting food and gathering medicinal plants.

“This land is our church, our supermarket and our pharmacy,” said Roland Willson, chief of the West Moberly First Nation, one of two indigenous groups who filed legal challenges against Site C.

The project took on national significance under Prime Minister Justin Trudeau, who called treaty rights a “sacred obligation” that Canada must uphold. During his campaign last year, Mr. Trudeau promised a “renewed, nation-to-nation relationship” with Canada’s indigenous peoples.

But this summer, the federal government granted permits that authorized BC Hydro to escalate the project. After indigenous groups sought a judicial review, the federal government claimed it was not legally obligated to consider the issue of treaty rights relating to Site C, and demanded that the groups prove their case in court, a process that experts said would most likely not conclude before the flooding occurred in 2024.

“This isn’t reconciliation, and it’s certainly not just or fair,” said Craig Benjamin, an indigenous rights campaigner for Amnesty International, which has called for a halt to Site C.

Mr. Benjamin sees a more serious problem for Canadian democracy in the government’s response. “That abuse of authority gets embedded into the system,” he said. “When you do that enough times for the rights of indigenous people, how badly does that warp the rights of all Canadians?”