Evaluating dam re-operation for freshwater conservation in the sustainable rivers project

Sustainable management of global water resources requires changing of dam operations to maintain river, floodplain and estuary ecosystems. Re-operating dams for ecological objectives must be evaluated rigorously because of the complexity of ecological responses to streamflow, uncertainty in the long-term and large-scale conservation impacts on freshwater ecosystems and the foregone environmental or social benefits from other uses of water. Prescribed releases at five demonstration sites in the Sustainable Rivers Project, a partnership between the US Army Corps of Engineers (Corps) and The Nature Conservancy to plan and implement environmental flow prescriptions at Corps dams nationwide, have been evaluated in terms of their immediate and direct ecological outcomes. Advancing dam re-operation as a freshwater conservation strategy at these and other sites will require additional evidence about longer-term and broader impacts on biodiversity and ecosystems. A pragmatic framework for monitoring and evaluating dam re-operation as a conservation strategy includes a balanced assessment of direct responses and long-term effects, institutional partnerships that can implement monitoring and evaluation at an ecosystem scale and improved reporting of scientific investigations to facilitate long-term monitoring and cross-site learning.