The Mapocho River () is a river in central Chile. It flows about from the Andes through the Santiago Metropolitan Region and the capital, Santiago, before joining the Maipo River. Fed by both snowmelt and rain, it runs generally from northeast to southwest through fourteen communes and divides the capital roughly in two.
Santiago was founded on the river's banks in 1541, and the river has shaped the city ever since. Spanish colonial authorities built embankments against its floods, and in the late 1880s engineers confined its central stretch to a concrete channel. For much of the 20th century the Mapocho received most of the city's untreated sewage. A sanitation program completed in 2010 ended the direct discharges, and Santiago's wastewater is now treated. Since then the river has become a focus of urban parks, cultural projects and recreation, and in 2025 Chilean authorities declared its full length an urban wetland. Floods, contamination from mining in the upper basin, and the river's declining water supply remain concerns.
Etymology The name is usually traced to Mapudungun and rendered as Mapu chuco, "water that penetrates the land". The 19th-century geographer Francisco Astaburuaga instead derived it from mapu ("land") and che ("people"), noting that the region was once called "land of people" and that the name later came to be applied only to the river.
Course Upper course The Mapocho begins at the confluence of the San Francisco River () and the Molina River () at La Ermita, in the commune of Lo Barnechea, in the Andes near Cerro El Plomo. The main tributary of the San Francisco is Yerba Loca Creek, which drains the protected area of the same name. The Molina is fed by the Iver Glacier, which lies on Cerro El Plomo. A few kilometers downstream the Mapocho receives Arrayán Creek () from the right and enters the urban area of Santiago.
The last western spurs of the Andes in this area turn the river toward the south. Near Cerro San Cristóbal and the Costanera Center complex it receives the waters of the artificial Canal San Carlos (), which carries water diverted from the Maipo and colors the Mapocho with the sediment it carries.
Through Santiago The river runs about through the city, bordered on its north bank by the Costanera Norte expressway and by Santa María and Presidente Salvador Allende avenues. Its south bank has a chain of parks, Costanera Sur avenue and several other roads, and an underground sewage interceptor.
From the Providencia area the river flows southwest to Plaza Baquedano, a focal point of the city. In colonial times the Mapocho split here into two branches, and the southern one was later converted into a promenade that is now Avenida Libertador General Bernardo O'Higgins (see History).
Through Providencia and Santiago the river runs in an artificial concrete channel about long, wide and deep, which contains 21 of its 40 bridges in the capital.
The river then turns northwest. Some of the city's best-known landmarks rose along its southern bank in this stretch, including the Parque Forestal, the Museo Nacional de Bellas Artes, the Mercado Central and the Estación Mapocho. In Renca and Quinta Normal three collapsible pneumatic gates feed the artificial navigable arm of the Parque de la Familia. Farther northwest, two highway bridges, part of the two branches of the Autopista Central, connect the north and south sides. The longer of them, the Gran Envergadura Bridge, is the largest on the river at .
Lower course Approximately at the longitude of the summit of Cerro Renca, the river changes from a northwesterly to a southwesterly direction. Near the southern end of Arturo Merino Benítez International Airport it turns south. In Pudahuel it receives Lampa Creek, and in Maipú the Zanjón de la Aguada (), the last two tributaries before it leaves the urban area. It then passes Padre Hurtado, Peñaflor and Talagante and empties into the Maipo River in El Monte.
In all, the river passes through fourteen communes: Lo Barnechea, Vitacura, Las Condes, Providencia, Santiago, Renca, Quinta Normal, Cerro Navia, Pudahuel, Maipú, Padre Hurtado, Peñaflor, Talagante and El Monte.
Watershed The upper Mapocho basin is bounded on the west by that of the Olivares River and on the east by that of Colina Creek, both of which drain south to the Maipo. To the north it borders several subbasins of the Juncal River, which flows into the Aconcagua River.
Hydrology The Mapocho has a nival-pluvial regime, meaning that it is fed by both snowmelt and rainfall. Rain is heaviest in winter, but in the upper basin flows peak in spring (September to November) as the mountain snowpack melts. Its mean annual flow at the Los Almendros gauging station, on the upper river, is about , and in its lower course the tributaries and drainage from the city change it to a mixed rain-and-snow regime. The river's water is heavily used. According to a 2004 national water directorate study, the reach downstream of the Canal San Carlos confluence supplies irrigation for about of farmland in communes to the west of Santiago.
History Pre-Columbian period Archaeological research in recent decades has indicated that an Inca settlement stood on the banks of the Mapocho before the Spanish arrived, and that Santiago was founded over it. Research based on early Spanish land-grant records indicates that, from the early 15th century until the Spanish arrival in 1540, the Incas and allied local groups built an extensive network of irrigation canals in the Mapocho and Maipo valleys, bringing thousands of hectares into cultivation. The longest canal drawn from the Mapocho ran through the Vitacura area.
Spanish colonial period Pedro de Valdivia reached the area in December 1540 and found the valley suffering from famine caused by drought. According to tradition, the local Promaucaes advised him to settle on an island between two arms of the river, beside a small hill called Huelén (now Cerro Santa Lucía). Recent archaeology has cast doubt on this account. In January 1541 the Spanish defeated the Picunches led by the chief Michimalonco in the battle of the Mapocho River, and on February 12, 1541, Valdivia founded the city of Santiago de Nueva Extremadura on the river's south bank, at the foot of Huelén.
An early picture of the river's relation to the city comes from the flood of July 1574, when the overflowing Mapocho ran through streets between the city's eastern edge and the sea, crossed the main plaza and the cabildo building, and swept away several Indigenous people trying to cross near the Merced church. The cabildo's clerk, Nicolás de Gárnica, rode through the city and recorded that the water reached the girths of the horses. Over time the city expanded across the river, and the farming district of La Chimba (now Recoleta and Independencia) grew up on the north bank.
In colonial times a smaller branch of the Mapocho left the main channel near today's Plaza Baquedano and ran south of the city center before rejoining the main channel beyond the present Plaza de la Constitución. It left a strip of land between the two channels on which central Santiago now stands. This southern channel was filled in during the 19th century, first to make way for a road called La Cañada and then the Alameda de las Delicias, later renamed Avenida Libertador General Bernardo O'Higgins. Several authors argue that this branch was never a true arm of the river, but only a dry bed that flooded when the Mapocho overflowed.
The first bridge in Santiago, the "puente de Palos" (timber bridge), linked the Calle Puente with La Chimba and was used for almost 150 years, until the 17th century. A second crossing, the stone bridge known as the Puente de Cal y Canto (Calicanto), was begun in 1767 under the corregidor Luis Manuel de Zañartu and finished in the early 1780s. Because of the river's severe winter floods, Zañartu also began a program of embankments (tajamares) in 1773 to protect the city. These became a fashionable promenade for the Creole elite.
Canalization In 1888, under President José Manuel Balmaceda and with revenue from the nitrate (saltpeter) boom, work began on the first canalization of the river. This first phase, roughly between Vicuña Mackenna and Fermín Vivaceta avenues, was designed by University of Chile engineer Valentín Martínez and completed in 1891. It contained winter floods and improved communication between the north and center of the city. Steel bridges without piers, some still in use, replaced the old wooden bridges and the Calicanto bridge, which had been destroyed by a flood in August 1888. The remaining sides of the old riverbed were filled in, which later allowed construction of the Estación Mapocho and the Parque Forestal on the south bank.
Until the 19th century the river marked the northern edge of Santiago. That is why the Estación Mapocho, later also the northern bus terminal, became the arrival point for trains from northern Chile, and why the Vega Central, the city's main produce market, and the Mercado Central were built beside it. Until the first half of the 20th century the channeled riverbed was a gathering place for homeless people and petty criminals.
21st century On April 12, 2005, the Costanera Norte toll expressway opened along the north bank and, in the channeled section, under the riverbed. The Mapocho Urbano Limpio sanitation project (see Water quality) was completed in 2010. In 2015 the Parque de la Familia opened, with an artificial calm-water arm that can be navigated, and the western riverbanks were cleared of trash, debris and brush. In the 2010s work also began on riverside developments on the south bank, including the Costanera Sur and the cycling projects Cicloparque Mapocho 42K, outside the riverbed, and a riverbed promenade, inside it.
In July 2026 the Santiago Metropolitan Regional Government opened a new public tender to build a flood-tolerant riverside promenade in the channeled riverbed, a project originally known as Mapocho Pedaleable. The multipurpose route would run along the south bank of the channel between the Padre Letelier bridge in Providencia and the Parque de los Reyes in Santiago. The design includes a pedestrian path wide, a bike lane, rest areas called "beaches", six access points, lighting, security cameras, street furniture, and landscaping with native and low-water-use plants. The reference budget is 22,360,588,000 Chilean pesos, with bid submissions due in September 2026 and the contract to be awarded in December. Two earlier tenders for the project, in 2023 and 2024, were declared void.
Floods The Mapocho is prone to large floods. Central Chile's heavy winter storms can bring up to of rain in a day, and this is one of the main causes of the river's historic floods.
Overflows have been recorded since the Spanish settlement. The earliest, in 1544, came when winter rains flooded both the Mapocho and the Maipo. Rain and snow between July 20 and 22, 1574, produced floods that destroyed the bridge to the south, killed Indigenous people and swept away houses and walls in colonial Santiago. Further floods followed in 1581 and 1597, the latter killing a considerable number of people.
In the 17th century the river overflowed in 1607 and in the spring of 1609, in the "great Pentecost flood", which brought a plague of mice and many deaths and led to the first embankments on the river. More floods came in 1618, 1647, 1650, 1683 and 1686. Those of 1687 and 1688 destroyed parts of the original embankments, and another section was swept away on November 17 and 18, 1694.