The Imperial Reservoir is an artificial lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 formed by the construction of the Imperial Diversion Dam across the Colorado River

Colorado River

The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

 in the Lower Colorado River Valley

Lower Colorado River Valley

The Lower Colorado River Valley is the river region of the lower Colorado River of the southwestern United States in North America that rises in the Rocky Mountains and has its outlet at the Colorado River Delta in the northern Sea of Cortez in northwestern Mexico, between the states of Baja...

 of Imperial County, California

Imperial County, California

Imperial County is a county located in the Imperial Valley, in the far southeast of the U.S. state of California, bordering both Arizona and Mexico. It is part of the El Centro Metropolitan Area, which encompasses all of Imperial County. The population as of 2000 was 142,361. The county seat is the...

, and Yuma County, Arizona

Yuma County, Arizona

-2010:Whereas according to the 2010 U.S. Census Bureau:*70.4% White*2.0% Black*1.6% Native American*1.2% Asian*0.2% Native Hawaiian or Pacific Islander*3.8% Two or more races*20.8% Other races*59.7% Hispanic or Latino -2000:...

. A component of the Imperial National Wildlife Refuge

Imperial National Wildlife Refuge

The Imperial National Wildlife Refuge protects wildlife habitat along of the lower Colorado River in Arizona and California, including the last un-channeled section before the river enters Mexico...

, the reservoir is 16 miles (25.7 km) northeast of Yuma, Arizona

Yuma, Arizona

Yuma is a city in and the county seat of Yuma County, Arizona, United States. It is located in the southwestern corner of the state, and the population of the city was 77,515 at the 2000 census, with a 2008 Census Bureau estimated population of 90,041....

.

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

Bill Williams River

The Bill Williams River is a river in western-central Arizona in Mohave County; the river proper is the northern border of La Paz County which it drains in the north, as well as areas of far western Yavapai County...

 from western Arizona. Upstream on the Colorado River, the basic feeder watershed to Imperial Reservoir is the Havasu-Mojave Lakes Watershed, of Lake Havasu

Lake Havasu

Lake Havasu is a large reservoir behind Parker Dam on the Colorado River, on the border between California and Arizona. Lake Havasu City sits on the lake's eastern shore. The lake has a capacity of . The concrete arch dam was built by the United States Bureau of Reclamation between 1934 and 1938...

.

Two dry wash watershed attempt to enter the Imperial Reservoir from western Arizona, south of the Bill Williams River: the Bouse

Bouse Wash

Bouse Wash is one of the larger eastern-bank dry washes that enter the Colorado River in western Arizona.Bouse Wash is located on the north end of the La Posa Plain and drains into the area along the Colorado River occupied by the Colorado River Indian Reservation, south of Parker, Arizona...

 and Tyson Wash

Tyson Wash

Tyson Wash is one of the larger eastern-bank dry washes that enter the Colorado River in western Arizona. It drains the La Posa Plain south-to-north and is also coincident with the Plain, ....

es. Both washes end on the eastern perimeter of the Colorado River Indian Reservation

Colorado River Indian Reservation

The Colorado River Indian Reservation is 189 miles west of Phoenix, Arizona, on highway 95. It lies in western La Paz County, Arizona, southeastern San Bernardino County, California, and northeastern Riverside County, California. It has a total land area of 432.22 sq mi , and most of it lies...

along the Colorado River. Neither enters the river proper, except in extreme flood stage.

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

External links

• Imperial Reservoir Watershed Map