Río Lerma

The Lerma River (Río Lerma) is Mexico's second longest river. It is a river in west-central Mexico that begins in Mexican Plateau at an altitude over above sea level, and ends where it empties into Lake Chapala, Mexico's largest lake, near Guadalajara, Jalisco. Lake Chapala is also the starting point of Río Grande de Santiago, which some treat as a continuation of the Lerma River. In combination, the two are often called the Lerma Santiago River (Río Lerma Santiago). The Lerma River is notorious for its pollution, but the water quality has demonstrated considerable improvement in recent years due mostly to government environmental programs and through a vast program of upgrading local sanitation infrastructure. The Lerma River originates from the Lerma lagoons near Almoloya del Río, on a plateau more than above sea level, and southeast from the city of Toluca. The lagoons receive their water from springs rising from basaltic volcanics that flow down from Monte de Las Cruces. These are located between the Valley of Toluca and the Basin of Mexico. The river forms the short border between the states of Querétaro and Michoacán then flows west-northwest through the state of Guanajuato. After turning southward, the river separates Guanajuato and Michoacán, and Michoacán and Jalisco before flowing, after a course of about , into Lake Chapala, west-southwest of La Barca. It has a length of . When it empties into Lake Chapala, the system stands at above sea level. Some people consider the long Río Grande de Santiago, which continues from Lake Chapala northwest towards the Pacific Ocean, to be a continuation of the Lerma River. During the 17th and 18th centuries, large haciendas were established along this river, including the Atenco Ranch, which was founded with bulls that belonged to Hernán Cortés. The bulls from this area are considered some of the finest stock for bullfighting. The river is dotted with cities such as Lerma and San Mateo Atenco to small picturesque villages with cultural significance such as Malinalco.