The Salton Sea is a saline, endorheic rift lake located directly on the San Andreas Fault. The lake occupies the lowest elevations of the Salton Sink in the Colorado Desert of Riverside and Imperial Counties in Southern California. Like Death Valley, it is located below sea level, with the current surface of the Salton Sea at 226 ft (69 m) below sea level. The deepest area of the sea is 5 ft (1.5 m) higher than the lowest point of Death Valley. The sea is fed by the New, Whitewater, and Alamo rivers, as well as a number of minor agricultural drainage systems and creeks.
It is estimated that for 3 million years, at least through all the years of the Pleistocene glacial age, the Colorado River worked to build its delta in the southern region of the Imperial Valley. Eventually, the delta had reached the western shore of the Gulf of California (the Sea of Cortez/Cortés) creating a massive dam which excluded the Salton Sea from the northern reaches of the Gulf. Meandering at random across the ever-growing fan-shaped mass, the river changed its course constantly. Occasionally shifting to the north, the river flowed into the isolated Salton basin, filling it with a large freshwater lake. Eventually, a significant river shift towards the south and into the Gulf of California abandoned the inland lake to likely evaporation and extinction.
As a result, the Salton Sink or Salton Basin has had a long history of alternately being occupied by a fresh water lake and being a dry, empty desert basin, all according to the random river flows, and the balance between inflow and evaporative loss. A lake would exist only when it was replenished by the river and rainfall, a cycle that repeated itself countless times over hundreds of thousands of years - most recently in 1905.
There is significant evidence that the basin was occupied periodically by multiple lakes. Wave-cut shorelines at various elevations are still preserved on the hillsides of the east and west margins of the present lake, the Salton Sea, showing that the basin was occupied intermittently as recently as a few hundred years ago. The last of the Pleistocene lakes to occupy the basin was Lake Cahuilla, also periodically identified on older maps as Lake LeConte, and the Blake Sea, after American professor and geologist William Phipps Blake.
The lake covers a surface area of approximately 376 sq mi (970 km2), the largest in California. While it varies in dimensions and area with changes in agricultural runoff and rain, it averages 15 mi (24 km) by 35 mi (56 km), with a maximum depth of 52 ft (16 m), giving a total volume of about 7,500,000 acre·ft (9.25 km3), and annual inflows averaging 1,360,000 acre·ft (1.68 km3). The lake's salinity, about 44 g/L, is greater than the waters of the Pacific Ocean (35 g/L), but less than that of the Great Salt Lake and is increasing by about 1 percent annually.[2