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
Risks to the Glen Canyon Dam Dam forming Lake Havasu, Palo Verde Dam, and other dams and reservoirs. Because Glen Canyon Dam is also the central element of the Colorado River Storage Project, a failure may, depending on the volumes of water released and the damage caused, limit or completely cut off water supply to residences or farmlands along the Colorado River, and even into southern California depending on damage to canal headworks. The failure of Glen Canyon Dam would also destroy up to 964 known archaeological sites, including 264 that it currently affects in the Grand Canyon. Risks to the Glen Canyon Dam Glen Canyon