Construction is expected to begin this spring on one of the largest renewable energy projects in New York since Niagara Falls was harnessed for hydropower more than a half-century ago.

By late 2025, a 339-mile high-voltage transmission line is expected to deliver enough hydropower from Quebec’s remote forests to supply about 20% of New York City’s needs. The first electricity will finally flow 17 years after developers set out to bury a power line along the bottoms of Lake Champlain and the Hudson River, assuming they clear one last regulatory hurdle and encounter no further challenges. Opponents still have concerns about the project’s environmental impacts.