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Lake Chalco was an endorheic lake formerly located in the Valley of Mexico, and was important for Mesoamerican cultural development in central Mexico. The lake was named after the ancient city of Chalco on its former eastern shore.
Lake Chalco and the other Mexican great lakes (the brackish lakes Texcoco, Zumpango and Xaltocan and the freshwater Xochimilco) formed the ancient Basin of Mexico lake system. These lakes were home to many Mesoamerican cultures including the Toltecs and the Aztecs.
Lake Chalco itself had a fresh water hydrologic structure due in large part to the artesian springs lining its south shore. This allowed extensive chinampa beds to be cultivated through the Aztec era. After the Spanish conquest of the Aztec Empire, these beds fell into disuse and were largely abandoned.
Starting during the Aztec era and continuing into 20th century, efforts were made to drain Lake Chalco and her sister lakes in order to avoid periodic flooding and to provide for expansion. The only lakes that are still in existence are a diminished Lake Xochimilco and the Lake of Zumpango.