Millions of dams fragment and degrade Earth’s riparian landscapes. This chapter examines linkages between dams, rivers, and the environment and is subdivided into three sections, including riparian impacts of dams, dam removal, and reservoir sediment management strategies. The latter is crucial to sustain downstream fluvial environments and water resource infrastructure. Trapping of fluvial sediments in upstream reservoirs results in downstream degradation of riparian environments by channel bed incision and terrestrialization of aquatic habitat. In North America and western Europe dam removal for environmental restoration is occurring at a brisk pace, but in Southeast Asia, South America, southeast Europe, and parts of Africa dam construction for hydropower is rapidly occurring. Dam removal is an emerging science with great potential to improve downstream riparian ecosystems. It is essential that government agencies develop strategies to sustainably manage reservoirs so that fluvial sediments can be reactivated and transported to downstream riparian and deltaic environments to offset subsidence and sea level rise.

Fresh waters are not amenable to protection by fortress conservation, since entire drainage basins can seldom be set aside. Site selection by conservation modelling has shortcomings because of the directional connectivity of river ecosystems. In the many cases where habitat degradation is the primary threat to freshwater biodiversity, restoration measures (that include riparia) may ameliorate matters, allowing species persistence or even recovery. However, rehabilitation is often the best that can be achieved.Mitigation of the barrier effects of dams by fishways have limited effectiveness, but complete removal of dams is an effective means of restoring connectivity.Ex situ (captive breeding, reintroduction, translocation) and in situ conservation measures – sometimes in combination – have been applied to a variety of freshwater animals, using new techniques such as eDNA for monitoring. Various international networks have been established recently to facilitate collaboration on conservation and improve data collection and sharing. There are thus reasons to be hopeful – rather than optimistic – about the prospects for preserving freshwater biodiversity in a warming world.