The Marañón River is under threat from an estimated 20 hydroelectric megadams (exact number remains undetermined, due to “muddled policy and lack of transparency in government”). Parties responsible for these developments are the Peruvian Government and large multinational companies. The Brazilian infrastructure giant Oderbrecht is behind several of these projects including one of the most contentious, Chadin II; this company is currently facing corruption charges for its involvement in the Petrobras scandal and links to the destructive Belo Monte dam in Brazil.

These dams will essentially destroy the Marañón River. The headwaters of the river will become a series of reservoirs and very few stretches of free flowing river will remain. This will be catastrophic to the unique ecosystems and extraordinarily high levels of endemism that the river supports. Many riverside villages will be inundated and destroyed, and it is likely that the livelihood of native communities downstream will be severely impacted.

The Marañón remains one of the last free-flowing tributaries to the Amazon basin; connecting vital sediment flows from the Andes to the rainforest below, together harboring some of the most species rich zones on earth. Current planning for hydropower lacks adequate regional and watershed-scale assessment of potential ecological impacts.


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Oil extraction in the Peruvian Amazon has been the cause of many social and environmental issues since it begun half a century ago. In recent years pipelines and ageing infrastructure are failing with increasing regularity; causing enormous environmental damage and health issues for indigenous Awajún communities living nearby. Many oil spills have made their way into tributaries which flow to the Marañon River and inevitably into the greater Amazon.

To get an idea of the social and environmental impacts; and how widespread this issue is watch Pastaza. This film is set on the Pastaza River, a major northern tributary to the Marañón.


There are many mining operations scattered throughout the Andes that leech pollution into tributaries which find their way to the Marañón River. Some of these outflows go unmonitored, with no-one to enforce environmental legislation. New mines are continually being proposed within this enormous watershed, while other mines will begin to reach the end of their lifecycle and become defunct, resulting in more environmental and social issues.

Small scale ‘artesenal mining’ can also create environmental issues. Mercury can be used in large quantities and discarded directly into the river. This issue will be compounded if dams are built and mercury is trapped in low oxygen environments.

The largest gold mine in the world resides in the province of Cajamarca. Although touted to bring development and progress to the region, the people are poorer than before the mine existed and now have to deal with the water contaminations from the poorly managed project. The people must also deal with the corruption that comes hand in hand with such large projects. Read More on Conga.

In the future, careful revision of proposed mining projects in the Marañón Watershed and enforcement of environmental controls help to manage or stop these developments before they become major issues.