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.