Oroville Dam is an earthfill embankment dam on the Feather River east of the city of Oroville, California in the United States. At high, it is the tallest dam in the U.S. and serves mainly for water supply, hydroelectricity generation and flood control. The dam impounds Lake Oroville, the second largest man-made lake in the state of California, capable of storing more than 3.5 million acre-feet (4.4 km³), and is located in the Sierra Nevada foothills east of the Sacramento Valley.