The Sobradinho Reservoir (Portuguese: Lago de Sobradinho) is a large reservoir located in Sobradinho, north of the Brazilian state of Bahia. The reservoir measures approximately 320 km (200 mi) long, 4,214 km (1,627 sq mi) in surface area, and a storage capacity of 34.1 km (8.2 cu mi) at its nominal elevation of 392.5 m (1,287.7 ft), making it the 15th largest reservoir (artificial lake) in the world. The lake encloses the waters of the São Francisco River, one of the largest and most important rivers in Brazil.

The reservoir, which represents 60.4% of the hydroelectric power resources of the Northeast of Brazil, has conditions to guarantee the power supply for the region for two years but its water level is highly variable. In some drought years the energy supply is threatened.

• Lago Artificial de Sobradinho
• Sobradinho lock Archived 2009-01-07 at the Wayback Machine
• Hidrovia de São Francisco
• Official site of city of Sobradinho, Bahia