Imperial Reservoir
Imperial Diversion Dam and Reservoir complex in 1972
Imperial Reservoir Show map of California Imperial Reservoir Show map of the United States
Location	Lower Colorado River Valley Imperial County, California Yuma County, Arizona
Coordinates	32°53′00″N 114°28′04″W / 32.8833°N 114.4677°W / 32.8833; -114.4677
Lake type	Reservoir
Primary inflows	Colorado River
Primary outflows	Colorado River
Catchment area	5,756 acres (2,329 ha)
Basin countries	United States
Managing agency	United States Bureau of Reclamation
Surface area	28 km2 (11 sq mi)
Water volume	160,000 acre⋅ft (200,000,000 m3)
Surface elevation	56 m (184 ft)
References	U.S. Geological Survey Geographic Names Information System: 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. Partially included in the Imperial National Wildlife Refuge, the reservoir is 16 miles (26 km) northeast of Yuma, Arizona.

Dry wash watersheds

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 attempt to enter the Imperial Reservoir from western Arizona, south of the Bill Williams River: the Bouse and Tyson Washes. Both washes end on the eastern perimeter of the Colorado River Indian Reservation along the Colorado River. Neither enters the river properly, except in the extreme flood stage.

No "lengthy" watersheds flow eastwards from California; all are short distances, in the extreme aridity of this desert region.