The Black Volta or Mouhoun (French: Volta noire) is a river that flows through Burkina Faso for approximately 1,352 km (840 mi) to the White Volta in Dagbon, Ghana, the upper end of Lake Volta. The source of the Black Volta is in the Cascades Region of Burkina Faso, close to Mount Tenakourou, the highest point of the country. Further downstream it forms part of the border between Ghana and Burkina Faso, and later between Ivory Coast and Ghana. Within Ghana, it marks the border between the Savannah and Bono regions. The Bui Dam, a hydroelectric power plant, is built on the river, just south of the Bui National Park, which the river bisects.