PORTLAND, Ore. (AP) — Federal regulators have approved a plan to demolish hydroelectric four dams on a California river and open up hundreds of miles of salmon habitat that would be the largest dam removal and river restoration project in the world when it goes forward.

The Federal Energy Regulatory Commission’s unanimous vote last month on the lower Klamath River dams is the last major regulatory hurdle and the biggest milestone for a $500 million demolition proposal championed by Native American tribes and environmentalists for years. The project would return the lower half of Califor...