Lake Cahuilla County Park

Lake Cahuilla was a prehistoric lake in California and northern Mexico. Located in the Coachella and Imperial valleys, it covered surface areas of 5,700 km2 to a height of 12 m above sea level during the Holocene. During earlier stages of the Pleistocene, the lake reached even higher elevations, up to 31–52 m above sea level. During the Holocene most of the water came from the Colorado River with little contribution from local runoff; in the Pleistocene local runoff was higher and it is possible that Lake Cahuilla was supported solely from local water sources during the Wisconsin glaciation. The lake overflowed close to Cerro Prieto into the Rio Hardy, eventually draining into the Gulf of California.

The lake formed several times during the Holocene, when water from the Colorado River was diverted into the Salton Trough. This tectonic depression forms the northern basin of the Gulf of California, but it was separated from the sea proper by the growth of the Colorado River Delta.