Imperial Reservoir Imperial Reservoir The Imperial Reservoir is an artificial lake formed by the construction of the Imperial Diversion Dam across the Colorado River in the Lower Colorado River Valley of Imperial County, California, and Yuma County, Arizona. A component of the Imperial National Wildlife Refuge, the reservoir is northeast of Yuma, Arizona. Dry washes are the major watershed feed systems to Imperial Reservoir. The next upstream major watershed feeder is the Bill Williams River from western Arizona. Upstream on the Colorado River, the basic feeder watershed to Imperial Reservoir is the Havasu-Mojave Lakes Watershed, of Lake Havasu. Two dry wash watershed
Imperial Valley and to the south the international boundary with the U.S. state of California and Baja California. The culture of the area blends those of the United States and Mexico, due to its regional history and geographic location along the international border. The Imperial Valley economy is based on agriculture. Imperial Valley was so named by the Imperial Land Company, in hopes of attracting settlers. Having done that it is now the home of the El Centro metropolitan area and also an economic center of California's government defined "South Border". Locally, the terms "Imperial Valley" and "Imperial County" are used synonymously.