The Salton Sea

The Salton Sea lies in the northern part of Imperial County and Borders Riverside County as well. The sea is the largest inland body of water in California. From north to south the sea is 35 miles long. It provides vast aquatic and wetland habitats in a region where water is scarce.


The Salton Sea, which is largely below sea level, was once the bottom of a prehistoric sea. The Gulf of California originally extended north into what is now the Imperial and Coachella valleys. Evidence of marine life and shells high on the sides of the local mountains indicates that the entire region experienced a tremendous upthrust which was the birth of the mountain ranges.

Gradually, vast quantities of silt, deposited by the Colorado River, formed a delta that closed off the northern arm of the basin from the Gulf. The Colorado River periodically overflowed its natural levees and filled the valley between the mountain ranges to form a vast lake (about 30 feet above sea level). Traces of the lake, named Lake Cahuilla (after and ancient tribe that inhabited the shoreline) can still be seen along the mountains to the west of the northerly end of the Salton Sea and in the sand dunes toward Glamis.

In 1901 the Imperial Canal was completed by the California Development Company and at that time the lake bed was dry. The Canal diverted water for irrigation from the Colorado River just upstream of the Mexican Border. After about four years the silt deposits led to an attempt to relocate the diversion a short distance downstream from the Mexican border.

In 1905, unusual winter floods breached the diversion structure. And for 15 months the entire flow of the Colorado River poured through the Mexicali and the Imperial Valley into the dry lake bed. This flooding threatened to destroy farms and homesteads of several thousand families. After arduous and expensive work, the river break was finally closed in the spring of 1907. The re established lake was named the 'Salton Sea'.

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Last update: September 16, 1997