"A magnitude 4.2 earthquake struck near Grand Coulee Dam, the largest U.S. hydropower facility, in northeastern Washington state on Tuesday, prompting an immediate inspection of the facility but leaving no visible damage, a spokeswoman said.

Operation of the Columbia River dam, which supplies electricity to 11 Western states, was not disrupted by the tremor, according to the spokeswoman, Lynne Brougher of the U.S. Bureau of Reclamation, the agency that runs the dam.

The U.S. Geological Survey reported the quake was centered about 25 miles (40 km) north of the dam near the town of Nespelem in heart of the sprawling Coleville Indian Reservation, an area ravaged by a major wildfire in recent days."

Steve Gorman reports for Reuters September 1, 2015. [2]