Salton Sea
The Salton Sea is a shallow, landlocked, highly saline endorheic lake in Riverside and Imperial counties in Southern California. It lies on the San Andreas Fault within the Salton Trough, which stretches to the Gulf of California in Mexico. The lake is about at its widest and longest. A 2023 report put the surface area at 318 square miles. The Salton Sea became a resort destination in the 20th century, but saw die-offs of fish and birds in the 1980s due to contamination from farm runoff, and clouds of toxic dust in the current century as evaporation exposed parts of the lake bed.
Over millions of years, the Colorado River had flowed into the Imperial Valley and deposited alluvium, creating fertile farmland, building up the terrain, and constantly moving its main course and river delta. For thousands of years, the river alternately flowed into the valley or diverted around it, creating either a salt lake called Lake Cahuilla or a dry desert basin, respectively. When the river diverted around the valley, the lake dried completely, as it did around 1580. Hundreds of archaeological sites have been found in this region, indicating possibly long-term Native American villages and temporary camps.
The modern lake was formed from an inflow of water from the Colorado River in 1905. Beginning in 1900, an irrigation canal was dug from the Colorado River to provide water to the Imperial Valley for farming. Water from spring floods broke through a canal head-gate, diverting a portion of the river flow into the Salton Basin for two years before repairs were completed. The water in the formerly dry lake bed created the modern lake.
During the early 20th century, the lake would have dried up, except that farmers used generous amounts of Colorado River water for irrigation and let the excess flow into the lake. In the 1950s and into the 1960s, the area became a resort destination, and communities grew with hotels and vacation homes. Birdwatching was also popular as the wetlands were a major resting stop on the Pacific Flyway. In the 1970s, scientists issued warnings that the lake would continue to shrink and become more inhospitable to wildlife. In the 1980s, contamination from farm runoff promoted the outbreak and spread of wildlife diseases. Massive die-offs of the avian populations have occurred, especially after the loss of several species of fish on which they depend. Salinity rose so high that large fish kills occurred, often blighting the beaches of the sea with their carcasses. Tourism was drastically reduced.
After 1999, the lake began to shrink as local agriculture used the water more efficiently, so less runoff flowed into the lake. As the lake bed became exposed, the winds sent clouds of toxic dust into nearby communities. The state is mainly responsible for fixing the problems. California lawmakers pledged to fund air-quality management projects in conjunction with the signing of the 2003 agreement to send more water to coastal cities. Local, state and federal bodies all had found minimal success dealing with the dust, dying wildlife, and other problems for which warnings had been issued decades before. In 2017, the Salton Sea Management Program was developed by the state. The Torres Martinez Desert Cahuilla Indians partnered with the state to restore shallow wetlands along the northern edge of the sea in 2018. Construction began in 2021 on the Species Conservation Habitat restoration and dust suppression project on the small delta of the New River. In 2025, water began flowing into the first of the SCH complex of shallow ponds.
History
Before the modern era
The Gulf of California would extend as far north as the city of Indio, some northwest of its current limits, were it not for the delta created by the Colorado River. Over three million years, through all of the Pleistocene, the river's delta expanded until it cut off the northern part of the gulf. Since then, the Colorado River has alternated between emptying into the basin, creating a freshwater lake, and emptying into the gulf, leaving the lake to dry and turn to desert. Wave-cut shorelines at various elevations record a repeated cycle of filling and drying over hundreds of thousands of years. The most recent freshwater lake was Lake Cahuilla, also known as the Blake Sea after American professor and geologist William Phipps Blake. It covered over, six times the area of the Salton Sea.Archaeological sites and radiocarbon dates indicate that the lake was filled three or four times over the last 1,300 years. When full, the lake would attract Native Americans to its shores. Hundreds of sites have been found, some possibly long-term villages and others temporary camps. The occupants ate at least four species of fish, birds, black-tailed jackrabbit, black-tailed cottontail rabbit, and sometimes deer and bighorn sheep. Among the plants they used were bulrush, cattail, mesquite, and saltbush. The Cahuilla people have an oral memory of the last lake, which existed in the 17th century and dried up soon after 1700.
Throughout the Spanish period of California's history, the area was referred to as the "Colorado Desert" after the Colorado River. In a railroad survey completed in 1855, it was called "the Valley of the Ancient Lake". On several old maps from the Library of Congress, it has been found labeled "Cahuilla Valley" and "Cabazon Valley". "Salt Creek" first appeared on a map in 1867, and "Salton Station" is on a railroad map from 1900, although this place had existed as a rail stop since the late 1870s. Until the advent of the modern sea, the Salton Sink was the site of a major salt-mining operation.
Modern formation
In 1900, under Governor James Budd, the California Development Company began construction of irrigation canals to divert water from the Colorado River into the Salton Sink, a dry lake bed. After construction of these irrigation canals, the Salton Sink became fertile, allowing farmers to plant crops.Within two years, the Alamo Canal became filled with silt from the Colorado River. Engineers tried to alleviate the blockages to no avail. Imperial Valley farmers, under considerable financial stress, pressured the California Development Company to resolve the problem. Engineer Charles Rockwood, faced with bankruptcy and "after mature deliberation", directed the construction of a breach in the bank of the Colorado River approximately south of the existing wooden headgates.
The breach, known as the Lower Mexican Intake and constructed without headgates and without the permission of the Mexican authorities, allowed the Colorado River to flow unimpeded into the canal and then to Imperial Valley farms. Rockwood's action in ordering the breach was later described as a "blunder so serious as to be practically criminal."
In 1905, heavy rainfall and snowmelt caused the Colorado River to swell, overrunning the third intake cut into the bank of the river and sending the flood into the Alamo Canal. The resulting flood poured down the canal and down two formerly dry arroyos, the New River in the west and the Alamo River in the east, each about long. Over about two years, these two newly created rivers carried the entire volume of the Colorado River into the Salton Sink.
The Southern Pacific Railroad tried to stop the flooding by dumping earth into the canal's headgates area, but the effort was not fast enough, and the river eroded deeper and deeper into the dry desert sand of the Imperial Valley. A large waterfall formed as a result and began cutting rapidly upstream along the path of the Alamo Canal that now was occupied by the Colorado. This waterfall was initially high but grew to high before the flow through the breach was stopped. Originally, the waterfall was feared to recede upstream to the true main path of the Colorado, becoming up to high, when it would be practically impossible to stop the flow.
As the basin filled, the town of Salton, a Southern Pacific Railroad siding, the New Liverpool Salt Company facility and miniature railroad, and Torres Martinez Desert Cahuilla Indian Reservation were submerged. Established in 1876, nearly half of the reservation was eventually flooded as the Indigenous people packed their belongings and headed into the mountains. The influx of water and the lack of any drainage from the basin resulted in the formation of the Salton Sea. On February 11, 1907, the breach was finally closed after substantial intervention by the Southern Pacific.
Agriculture, tourism and wildlife proliferate
In the 1920s, agriculture had boomed in the valley as the Imperial Irrigation District delivered large quantities of Colorado River water to irrigate the crops. The lake would have dried up naturally, but with flood irrigation being commonly used, plenty of water ran off the farms into the lake and kept it full. The district holds senior rights to water from the Colorado River according to Doctrine of Prior Appropriation, which states that whoever first puts a quantity of water from a given source to beneficial use gains the right to use that quantity of water from that source in future. In 1930, a wildlife refuge was established on some wetlands along the edge of the lake that had attracted many birds. The fish flourished in the lake and provided a source of food for massive populations of migratory birds. Birdwatchers flocked to this new refuge in the middle of a desert.The continuing intermittent flooding of the Imperial Valley from the Colorado River ended with the construction of Hoover Dam. Imperial Dam, built in 1938, serves as a desilting dam for water entering the irrigation canals.
In the 1950s and into the 1960s, the communities expanded as the area's reputation as a resort destination and sport fishery grew. Hotels and yacht clubs were built on the shore along with homes and schools. Resorts in communities like Bombay Beach hosted entertainers such as Frank Sinatra, The Beach Boys and Bing Crosby. Yacht clubs held parties at night and golf courses provided recreation. Many people came for boating activities such as water skiing and fishing as stocked fish proliferated. Lakeshore communities grew as vacation homes were built. More than 1.5 million visitors visited annually at the peak.