Colorado River Aqueduct, Water conveyance system in Southern California, US

The Colorado River Aqueduct is a 242 mi (389 km) water conveyance operated by the Metropolitan Water District of Southern California. It draws water from the Colorado River at Lake Havasu on the California–Arizona border and carries it west across the Mojave and Colorado deserts to the east side of the Santa Ana Mountains. The system comprises two reservoirs, five pumping stations, 62 mi of canals, 92 mi of tunnels and 84 mi of buried conduit and siphons.

William Mulholland first looked to the Colorado River in 1923 after the Owens Valley could no longer supply Los Angeles. The Metropolitan Water District was incorporated on December 6, 1928, and in 1931 its board chose the Parker route, backed by a $220 million bond approved on September 29, 1931. Work began in January 1933 near Thousand Palms; the aqueduct was finished in 1935 and water first flowed on January 7, 1939.

The aqueduct represents a human effort to reshape the land and make settlement possible where water was scarce. For residents across Southern California, it remains a symbol of the region's growth and dependence on distant water sources.

Most of the aqueduct is not open to public access, but portions are visible from nearby roads and viewpoints along its route. Visiting related water management sites or learning about the system helps understand how the region receives its water supply.

The aqueduct's five pumping stations lift water about 1,600 feet in total, from the Colorado River near Parker Dam to an elevation of 1,800 feet above sea level in the Eagle Mountains. The first lift raises water into the Whipple Mountains; at Iron Mountain it is raised another 144 feet. In 1955 the American Society of Civil Engineers named the system one of its "Seven Modern Civil Engineering Wonders".