Twin Buttes Reservoir is an artificial lake located about 6 mi (9.7 km) southwest of the city of San Angelo, Texas, and immediately upstream from Lake Nasworthy. Construction on Twin Buttes Dam to form the reservoir was completed in 1963. The dam is an unusual one – it dams the Middle and South Concho Rivers separately; a stabilization channel runs between the two sides of the lake. Water levels fell significantly during the 2010–13 Southern United States drought and remained low into 2014.