Course of the Colorado River into the Virgin River, which ran southward through what is now Overton Arm to join the Colorado River near the now-ghost town of St. Thomas, Nevada. At Hoover Dam, the Colorado turns due south through Black Canyon, a direction it will follow for the remainder of its course to the Gulf of California. It passes under the Mike O'Callaghan–Pat Tillman Memorial Bridge (Hoover Dam Bypass), the highest concrete arch bridge in the world, carrying U.S. Route 93 at a height of above the Colorado River. At the end of Black Canyon the Colorado widens into Lake Mohave, created by the
Bemposta Dam Bemposta Dam Bemposta Dam () is a concrete arch dam on the Douro, where the river forms the national border line between Spain and Portugal. It is located in the municipality Mogadouro, in Bragança District, Portugal. Construction of the dam began in 1957. The dam was completed in 1964. It is owned by "Companhia Portuguesa de Produção de Electricidade" (CPPE). Bemposta Dam is an (height above foundation) and arch dam with a crest altitude of 408 m. The volume of the dam is 316,000 m³. The dam contains four crest spillways (maximum discharge 11,500 m³/s) and one bottom outlet (maximum