Colorado River as 2 billion years. The of the river that flow through the Grand Canyon are largely encompassed by Grand Canyon National Park and are known for their difficult whitewater, separated by pools that reach up to in depth. At the lower end of Grand Canyon, the Colorado widens into Lake Mead, the largest reservoir in the continental United States, formed by Hoover Dam on the border of Arizona and Nevada. Situated southeast of metropolitan Las Vegas, the dam is an integral component for management of the Colorado River, controlling floods and storing water for farms and cities in the lower
Colorado River Colorado River basin. Below the dam the river passes under the Mike O'Callaghan–Pat Tillman Memorial Bridge – which at nearly above the water is the highest concrete arch bridge in the Western Hemisphere – and then turns due south towards Mexico, defining the Arizona–Nevada and Arizona–California borders. After leaving the confines of the Black Canyon, the river emerges from the Colorado Plateau into the Lower Colorado River Valley (LCRV), a desert region dependent on irrigation agriculture and tourism and also home to several major Indian reservations. The river widens here to a broad, moderately deep waterway averaging wide and reaching