Round Butte Dam is a rockfill-type hydroelectric dam on the Deschutes River, in the U.S. state of Oregon. Located in Jefferson County and owned by the power company Portland General Electric, its reservoir is called Lake Billy Chinook. The dam was completed in 1965 after three years of construction. More than 10 million tons of earth-fill were used to create this 440-foot tall, 1,320-foot wide, and 1,570-foot thick at the base storage dam.