Prior to 1942, irrigation water delivered to the Imperial Valley was diverted from the Colorado River near Pilot Knob through Mexico to bypass the Imperial sand dunes west of Yuma and into the IID-operated Alamo Canal (also known as the Imperial Canal). Since 1942, water has been diverted at Imperial Dam on the Colorado River through the 82-mile All-American Canal, all of which the IID operates and maintains, although the structures are owned by the U.S. Bureau of Reclamation.