The Andean Amazon is in the midst of a hydropower boom. More than 150 new dams are proposed across several countries, with more already under construction. Environmental impacts are assessed for individual dams—but what is the combined cost of the hydropower explosion for biodiversity, fisheries, navigation, and other benefits provided by intact rivers? This multidisciplinary team will develop a framework for evaluating cumulative impacts in areas of rapid hydropower growth. The new models will guide design of more sustainable dam networks that meet hydropower targets while preserving key ecosystem services.