California’s Largest Lake

Caitlin Dempsey


In 1905, floodwater from the Colorado River burst an irrigation canal being built in the Imperial Valley, flooding the Salton Sink and forming the Salton Sea. Water poured into the low-lying basin for two years before repairs were completed. A landlocked lake with no natural source of water, irrigation runoff from the Imperial and Coachella valleys, as well as local rivers, have kept Salton Sea filled.

As California’s largest lake, the catchment area of Salton Sea is 8,360 square miles (21,700 square kilometers).

This photo from the International Space Station shows the location of Salton Sea between Imperial and Coachella Valleys.  Image; NASA, June 12, 2002
This photo from the International Space Station shows the location of Salton Sea between Imperial and Coachella Valleys. Image; NASA, June 12, 2002

A shallow, saline, endorheic rift lake, Salton Sea has continued to increase in salinity as water evaporation leaves behind salt deposits. Salton Sea has a higher salinity (60 parts per thousand (PPT)) than the ocean (about 35 PPT).

As agricultural run-off has shrunk over the years due to more efficient farming practices and water regulations, Salton Sea has been shrinking. Tim Krantz, an environmental studies professor and Salton Sea expert at the University of Redlands noted in 2015 to NASA, “The changes from 1984 to 2015 [in the shoreline of Salton Sea] are the result of other water conservation activities in the watershed, such as wastewater treatment going online in Mexicali, and lining of the Coachella and All-American diversion canals from the Colorado River. These are all good things, but they mean less water in the Salton Sea.”

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Photo of exposed boat docks in the dry bed of Salton Sea.
Old boat docks are now surrounded by sand and salt as the Salton Sea continues to evaporate. Photo: Doug Barnum. USGS, Public domain.

Increased salinity, shrinking water levels, and algae blooms are all continuing problems plaguing Salton Sea. When the Sea was formed in 1905, its salinity levels were much lower and creational fishing was an important industry in the area for about 60 years. Today, the salinity levels are too high for most fish to survive in the lake with the exception of a now small population of tilapia (introduced in the 1960s to combat algae) and a native species, the desert pupfish (. Both species can tolerate high salinity and water temperatures.

The survival of this man-made lake is dependent upon a continued flow of water from the Imperial Valley. Salton Sea has since become an important stopover point on the Pacific Flyway for migratory water birds as well as several endangered species and Species of Special Concern like the Yuma clapper rail (Rallus longirostris yumanensis), Burrowing owl (Athene cunicularia), and the California brown pelican (Pelecanus occidentalis).

A flock of white pelicans at Salton Sea.
While pelicans of one of many species of birds that use the Salton Sea. Image: Douglas Barnum, USGS. Public domain

The California Fish and Wildlife services estimates that “95 percent of the North American population of eared grebes may use the Sea, 90 percent of American white pelicans, 50 percent of ruddy ducks and 40 percent of Yuma clapper rails” use the lake.

The shrinking water level and rising salinity have dramatically lowered the viability of fish that can live in the lake which, in turn, has affected the populations of birds that depend on the area. As birds crowd into the smaller areas of wetland available at Salton Sea, avian cholera outbreaks are devastating bird populations.

Toxic dust that blows up from the exposed areas of lake bed has adversely affected people living in the area as well. Plans to reduce the environmental impact to both humans and wildlife are still ongoing.


Hansen, K. (2015, October 9). Shrinking shoreline of the Salton sea. NASA Earth Observatory.

U.S. Fish and Wildlife Service. (2011, May 23). Endangered and sensitive species, Salton Sea

Wilson, J. (2019, February 8). Salton sea: Fish and the birds that fed on them wiped out this winter. Desert Sun.


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About the author
Caitlin Dempsey
Caitlin Dempsey is the editor of Geography Realm and holds a master's degree in Geography from UCLA as well as a Master of Library and Information Science (MLIS) from SJSU.