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
Chickamauga Dam to become unsafe for continued use some time before 2023. In October 2004 TVA installed a new warning system to alert individuals downstream when the dam is releasing water. The warning measures include strobe lights, signs and alarm horns. TVA conducts periodic maintenance on Chickamauga Dam using sawcut expansion holes, a type of expansion joint used in concrete construction. In 2010, engineering contractor S&ME used a Geoprobe drill to open and repair the expansion holes and cut new joints. Chickamauga Dam Chickamauga Dam is a hydroelectric dam on the Tennessee River in Chattanooga, Tennessee, United States. The dam is owned