Madeira River Basin

Hydropower dams in the heart of the Amazon

The 1,100 km long Madeira River, while a tributary of the Amazon River, is a great waterway in and of its own right.
In fact, the Madiera River Basin makes up 20% of the entire Amazon Basin. And it carries half of the Amazon’s sediment load, providing critical nutrients to downstream species and farming communities.

Over 750 known species of fish are found in the region, which provide protein for the diets of 950,000 people in Bolivia alone.

Dams on the horizon

The Madeira hydroelectric complex is the largest infrastructure project in South America. It consists of the construction of four hydropower dams in Brazil and Bolivia — the Jirau, Santo Antonio, Cachuela Esperanza, and Guayaramerin.
Two of these dams, the Jirau and Santo Antonio, are expected to generate a combined 6,450 MW of electricity, or 8% of Brazil’s energy mix.

The project also includes the construction of a lock system. This would make over 4,000 km of river navigable, facilitating transport of agriculture and forest products to population centers and ports along the coast.

A shadowy future

Yet the full extent of the environmental and social impacts of the project remains unclear. 

An estimated 1 million km2 of land could suffer indirectly from the finalized complex. Although an environmental assessment for the whole complex was commissioned by the investment promoters, it was never used to reach social agreements with civil society.

Other problems are expected from the complex, including:
  • clear-cutting of pristine forests to make way for the estimated 100,000 migrants who will move into the area to support construction
  • blockage of sediment flows, impacting downstream farmers dependent on the nutrient-rich silt
  • mercury leaching from years of gold prospecting
  • blockage of the breeding grounds of migratory fish, harming both these species and the livelihoods of the fishermen who depend on them
  • the proliferation of malaria-carrying insects.
 / ©: Gustavo YBARRA / WWF-Canon
Boats on the river. CIM (Iténez-Mamoré Corridor), Bolivia.
© Gustavo YBARRA / WWF-Canon

An incredible journey

The dourada (Brachyplatystoma rousseauxii), a species of catfish, is just one of the migratory fish species that is at risk from dams on the Madeira River.
With one of the longest migrations of any fish in the world, the dourada travel over 3,000 km each year from the Amazon Estuary to reproduce in the Andean foothills. They take four to five months to make the journey, swimming up to 19 km per day.

Like the dourada, 80% of commercially fished species in Bolivian rivers are migratory. This includes other species of catfish (Pseudoplatystoma fasciatum), cod (Brachyplatystoma filamentosum), and red belly pacu (Piaractus brachypomus).

Despite measures to allow the fish to pass through the Madeira dams, this migration will be impeded, damaging fisheries and people’s livelihoods.

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