Dam choices: Analyses for multiple needs

Environmentalists often go to great lengths to block the construction of new dams because dams interfere with fish migration, inundate terrestrial habitats, and interrupt natural flows that are necessary for critical ecosystem processes. However, few environmental issues are so simplistically black and white, and dams are no exception. Dams can be an important source of clean energy and for poor nations such as Laos or Cambodia, hydropower is an export that can be a foundation for poverty alleviation. The right question is not how to prevent construction of any new dams, but rather what the optimal portfolio of dams is for meeting our energy and fisheries needs while also securing as much biodiversity insurance as possible for our changing world. Ziv et al. (1) from Princeton University and the World Fish Center in Cambodia ask that right question. Specifically, they combine an ingenious model of fish migration in the mainstem Mekong River and its tributaries with scenarios of new dam construction to identify optimal dam deployments throughout the Mekong tributaries (1).