Reducing the ecosystem impacts of dams

Ecology Around the world, tens of thousands of dams regulate river flow and provide electrical power. By altering water and sediment flows, dams influence downstream ecosystems. In a Perspective, Poff and Schmidt explain that negative downstream effects can be ameliorated at low cost by managing either daily or seasonal water releases to make allowances for local ecosystem requirements. For example, avoiding water releases from a dam on the Colorado River for a few weekends each year could help large insects to recover, thereby also providing food for local fishes. Science , this issue p. [1099][1] [1]: /lookup/doi/10.1126/science.aah4926