For thousands of years, the Colorado River would overflow its banks and flow into the Salton Basin. This cycle occurred approximately every 100 to 150 years, taking up to 20 years to fill the basin and 60 years to recede. Surveys along the relic shoreline have found hundreds of fishing camps and villages. William P. Blake, a geologist for the 1853 U.S. government exploration team for the transcontinental railroad, asked the Cahuilla (pronounced Kah-wee-ah) about the shoreline evidence of the ancient lake and heard accounts of ‘a great water’ that covered the whole valley. Cahuilla ancestors lived in the mountains, coming down to fish and hunt geese and ducks. As the waters subsided, they moved their villages down from the mountains, following the shore. The waters suddenly returned, overwhelming villagers, driving them back to the mountains.

Parallel lines of stone fish traps indicate that camps were relocated to follow the receding shoreline. Excavations have yielded fish bones from at least four species of fish native to the Colorado River and the Gulf of California, including the razorback sucker and the bonytail chub. Located among the Santa Rosa Mountains outside Riverside, California, the Lake Cahuilla shoreline was established by locating geomorphological features with global positioning systems and plotting these in a geographic information system (GIS). Further evidence of Lake Cahuilla has been obtained from archaeological sites along the ancient shoreline, including fish traps, bones, and other lake-related remains. The periodicity of Lake Cahuilla episodes has been estimated based on carbon dates of the travertine deposits and other organic archaeological evidence, indicating that the lake was full two-thirds of the time over the past 1,300 yrs of record. The current body of water in the basin is the Salton Sea.