Sediment Mismanagement Puts Reservoirs and Ecosystems at Risk

https://eos.org/opinions/sediment-mismanagement-puts-reservoirs-and-ecosystems-at-risk

Source: By Desirée Tullos, Peter A. Nelson, Rollin H. Hotchkiss, and David Wegner, Eos/AGU. 

Excerpt: Dams store water flowing down rivers and streams in reservoirs, providing protection from floods. Dams also serve as sources of electrical power, and they provide water for domestic and irrigation uses and flat-water recreation. By design and default, most dams in the United States also store sediment, indefinitely. Sediment accumulation behind U.S. dams has drastically reduced the total storage capacity of reservoirs. Sedimentation is estimated to have reduced the absolute water storage capacity of U.S. reservoirs by 10%–35%. Consequently, on a per capita basis, the water storage capacity of U.S. reservoirs today is about what it was in the 1940s–1950s, despite there being more dams [Randle et al., 2019]. ...At the same time, reaches downstream of dams have been deprived of sediment, resulting in declines in the health of downstream habitats and organisms [Ligon et al., 1995]. ...Managing reservoir sediments in the United States has historically involved dredging, excavation, and removal of sediment to off-site locations. These approaches are expensive and do not restore sediment continuity with downstream river channels. Alternative management approaches have revealed that mobilizing and passing sediment through reservoirs to downstream reaches can maintain or restore both reservoir capacity and downstream ecosystems....