The Lerma Santiago River (Río Lerma Santiago) is Mexico's longest river. It is a 2,600-km-long (1,600 mile-long) river in west-central Mexico that begins in Mexico's central plateau at an altitude over 3,000 meters above sea level, and ends where it pours into the giant Lake Chapala (at 1,510 meters above sea level), near Guadalajara, Jalisco. The 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 massive upgrading projects of sanitation works. Lake Chapala from space, April 1994 Lake Chapala (Spanish: Lago de Chapala) is Mexicos largest freshwater lake. ... This article is about the Mexican city of Guadalajara. ... Jalisco is one of the states of the United Mexican States (Mexico). ...

River's Path

The Lerma River originates from the Lerma lagoons near Almaloya del Río, on a plateau more than 2,600 meters above sea level, and 24 km southeast of Toluca. The lagoons receive their water from springs rising from basaltic volcanics that flow down from Monte de Las Cruces. This article is about a city in Mexico. ...

The river flows northwestward through México State. The river defines the short border between the Mexican states of Querétaro and Michoacán, and then continues mostly northwest through Guanajuato, one of its tributaries flows through the historic town of Irapuato. Then it loops south where it defines the border between Guanajuato and Michoacán, then between Michoacán and Jalisco, after which the Lerma enters Lake Chapala. The United Mexican States, or Mexico, is a federal republic, comprising 31 states. ... Querétaro (formal name: Querétaro Arteaga) is a state in central Mexico. ... Michoacán de Ocampo (From michamacuan, Nahuatl for the place of the fishermen) is one of the 31 constituent states of Mexico. ... Guanajuato is a state in the central highlands of Mexico. ... Main square of Irapuato Irapuato is a city in the Mexican state of Guanajuato, lying on the Irapuato River, a tributary of the Lerma River. ... Jalisco is one of the states of the United Mexican States (Mexico). ... Lake Chapala from space, April 1994 Lake Chapala (Spanish: Lago de Chapala) is Mexicos largest freshwater lake. ...

Some people consider the 400-km-long Río Grande de Santiago, which continues from Lake Chapala northwest towards the Pacific Ocean, to be a continuation of the Río Lerma. If Lake Chapala were to overflow, the excess water would flow into the Río Grande de Santiago, but this has not occurred since 1977. The Río Grande de Santiago (not to be confused with the Rio Grande river forming part of the Mexico/United States border) is a river in Mexico. ... For the album by Ash, see 1977 (album). ...

Importance in Mexico

The Lerma River is not navigable by water craft, but it is critical to regional agricultural irrigation, and its flow powers several hydroelectric plants.

The Lerma's water is also a source for the municipal water supply in the Guadalajara and Toluca metropolitan areas.

Pollution

The Lerma's historic reputation for polluted water has been partially mitigated by extensive government environmental programs. The Lerma River basin now has 44 wastewater treatment plants to help reduce toxic runoff into the Lerma.

Another environmental threat is overuse of the Lerma's water supply, which has led to a decrease in Lake Chapala's water level, and threatens the Lake Chapala Lerma River watershed aquifers.

Sources

• Microfarm Project using Simplified Hydroponics and Fertigation in the Lerma Chapala Basin, Mexico
• sanitation_health/wpcontrol/ch20.htm Case Study VIII* - Lerma-Chapala Basin, Mexico, World Health Organization
• The Mexican Bajío
• Mexico Travel: The Toluca Excursion