The Great Basin Divide in the western United States is the ridgeline that separates the Great Basin from the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

watershed, which completely surrounds it. The Great Basin is the largest set of contiguous endorheic watersheds of North America, including six entire

USGS The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

watershed

subregions A subregion is a part of a larger region or continent and is usually based on location. Cardinal directions, such as south are commonly used to define a subregion. United Nations subregions The Statistics Division of the United Nations (UN) ...

. It contains the watersheds of several large prehistoric and still-existing lakes, most notably

Lake Bonneville Lake Bonneville was the largest Late Pleistocene paleolake in the Great Basin of western North America. It was a pluvial lake that formed in response to an increase in precipitation and a decrease in evaporation as a result of cooler temperature ...

Lake Lahontan Lake Lahontan was a large endorheic Pleistocene lake of modern northwestern Nevada that extended into northeastern California and southern Oregon. The area of the former lake is a large portion of the Great Basin that borders the Sacramento Ri ...

Lake Manly Lake Manly was a pluvial lake in Death Valley, California, covering much of Death Valley with a surface area of during the so-called "Blackwelder stand". Water levels varied through its history, and the chronology is further complicated by act ...

, and the

Salton Sea The Salton Sea is a shallow, landlocked, highly saline body of water in Riverside and Imperial counties at the southern end of the U.S. state of California. It lies on the San Andreas Fault within the Salton Trough that stretches to the Gu ...

. As such, it occupies most of present-day Nevada, about half of Utah, large parts of eastern California and Oregon, and small parts of Idaho, Wyoming, and Baja California. The arid climate of this area ensures that none of the major lake basins are filled to overflowing, and thus no precipitation falling into them reaches the sea. On the other hand, precipitation falling on the exterior of the Great Basin Divide does (theoretically) reach the Pacific Ocean, through a number of different channels. Roughly speaking, the area to the north and northeast of the Great Basin drains into the Columbia River, mostly via the

Snake River The Snake River is a major river of the greater Pacific Northwest region in the United States. At long, it is the largest tributary of the Columbia River, in turn, the largest North American river that empties into the Pacific Ocean. The Snak ...

. Likewise, the area to the south and southeast drains into the

Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid watershed that encompasses parts of seven U.S. s ...

, a good part of it via the Green River. The area west of the Great Basin is drained by the

Klamath River The Klamath River (Karuk: ''Ishkêesh'', Klamath: ''Koke'', Yurok: ''Hehlkeek 'We-Roy'') flows through Oregon and northern California in the United States, emptying into the Pacific Ocean. By average discharge, the Klamath is the second larges ...

, the Central Valley of California (

Sacramento ) , image_map = Sacramento County California Incorporated and Unincorporated areas Sacramento Highlighted.svg , mapsize = 250x200px , map_caption = Location within Sacramento ...

and San Joaquin Rivers), and various small rivers of southern California and northern Baja.

References

{{Great Basin watersheds Drainage divides Geography of the United States