The age of Lake Chapala, which is located in one of the youngest geological areas of the American continent, has been established by means of carbon-14 dating of wood samples encountered in the sediments.

[2] Shortly after, a few consecutive years of poor rainfall dramatically decreased the water level of the lake.

Simultaneously, the waters of Lake Chapala are polluted by municipal, industrial and agricultural wastes, coming primarily from the Lerma River.

[10] Although it is still subject to agricultural, domestic, and industrial sources of contamination, the actual levels of hazardous materials have not been officially assessed with regularity.

[12][13] The lake is a critical habitat for several species of migratory birds, such as the American white pelican, and home to thousands of indigenous plants and animals.

[15] The essentially harmless, semi-aquatic obscurus subspecies of the Mexican garter snake is restricted to the lake.

[18] Other aquatic species found only in the lake and associated water systems are four cambarid crayfish: Cambarellus chapalanus, C. lermensis, C. prolixus and Procambarus digueti.

[20] Beginning in the 1950s, because of the pleasant climate and attractive scenery, a substantial colony of retirees, including many from the United States and Canada, has been established along the lake's shore,[21] particularly in the town of Ajijic, located just west of the city of Chapala, but also in many other towns, such as San Nicolas De Ibarra, San Juan Tecomatlan and Tlachichilco Del Carmen.