The world’s rivers are in crisis, and the drivers of river degradation are numerous. While pollution in its many forms impairs the quality of our rivers’ waters, dams impact both water quality and the very functionality of rivers, of planetary life cycle processes. Roughly two-thirds of the world's rivers have suffered harm from the 50,000 large dams that have been built over the past century. Many of the world's great rivers – such as the Indus, the Colorado, and the Yellow rivers – no longer reach the ocean, turning once-productive deltas into biological deserts. More than tropical rainforests, marine environments, or coastal wetlands, freshwater ecosystems are experiencing the greatest loss of biodiversity, in large measure due to dams. Over the past 40 years, freshwater ecosystems have lost 50% of their populations and over a third of remaining freshwater fish species are threatened with extinction[1].