Santiago, Chile
Focus area
A river that runs through the center of Santiago, where sanitation has improved but litter and trace contaminants remain a concern.
In brief
The Mapocho flows about 110 kilometers from the Andes through the Santiago metropolitan area and joins the Maipo River near El Monte. It crosses 16 communes, and in January 2026 Chile's Ministry of the Environment recognized 647 hectares of its banks in 13 of those communes as an urban wetland.
For decades much of Santiago's wastewater reached the Mapocho. A 28.5-kilometer underground interceptor now carries sewage to the La Farfana and Mapocho-Trebal treatment plants, and a local foundation told the outlet Pauta in 2024 that the river no longer receives wastewater but still collects debris from points across the city.
Some pressures remain. A 2024 study in Science of the Total Environment detected 73 contaminants of emerging concern in wastewater samples, found none upstream of the treatment plants, and attributed those found downstream mainly to effluent discharge. A 2022 international study of 258 rivers placed the Mapocho among the more pharmaceutically contaminated, as reported by El Mostrador. In 2024, groups at the Maipo estuary also described heavy rains carrying large amounts of plastic and construction waste downriver from Santiago.
Our focus is on supporting locally led work: simple riverbank surveys, litter tracking, waste prevention at its source, community cleanups organized with local groups, and support for the Chilean organizations already caring for the river.
Cleaner banks do not make water safe to drink. Access to safe drinking water is a separate program that is led by qualified local specialists.
Fundación Mapocho Vivo describes itself as a nonprofit that works to conserve the river's natural heritage through school visits, reforestation and river cleanups. Press coverage in 2024 reported more than 25 tons of garbage cleaned. Biocorredor Mapocho El Trebal is a neighborhood group, formed in 2020, that cares for the river corridor between Maipú and Padre Hurtado, and sources describe it as one of the groups behind the wetland recognition.
Fundación Cosmos administers the Río Maipo wetland sanctuary at the end of the wider basin. In 2024 it spoke publicly about plastic reaching the estuary. Its sources do not tie it to the Mapocho itself, so it appears here as a related organization to learn from.
The next steps are to listen: to speak with these groups and with Santiago's water and wetland specialists, learn what monitoring and cleanup work already exists, and find where local teams would welcome extra hands or equipment.
Organization to exploreWorks on this waterway
A Chilean nonprofit foundation focused on the Mapocho River. Its website lists educational workshops and school field trips, reforestation, river cleanups and nature-based art and wellbeing activities. The Clinic (2024) reports it works along the river's 16 communes and 110 kilometers, and Pauta (2024) reports more than 25 tons of garbage cleaned.
Organization to exploreWorks on this waterway
A community environmental group formed in 2020 by neighbors who began by clearing trash from the Mapocho between Maipú and Padre Hurtado. Its stated mission is research, protection, restoration and conservation of the Mapocho El Trebal biological corridor, and it works through environmental education and community action. Sources describe it as one of the civil groups behind the river's urban wetland recognition. Its only public page we found is on Instagram, and a source says it aims to become a formal foundation.
Official website of Biocorredor Mapocho El Trebal (external site)
Organization to exploreWorks in a related habitat
A Chilean nonprofit foundation, established in 2014, that designs and manages nature-based public spaces and urban wetland projects. It administers the Río Maipo wetland nature sanctuary, about 60 hectares at the mouth of the Maipo, the river the Mapocho joins. In June 2024 La Tercera quoted its staff on tons of plastic and other waste reaching the estuary after heavy rains. Sources do not tie it to the Mapocho itself.
If you work on or live near Mapocho River, we would like to hear what would genuinely help.
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