Expertise on the project of erasure of Vezins and La-Roche-qui-Boit works on the Selune

The Selune is a coastal river in Normandy with two dams (Vezins and Roche-qui-Boit) which produce electric power. Only one third of the river is now accessible to migratory fishes and the quality of dam waters is bad. As previous studies recommended not to renew dam concessions and authorisations in order to halt the loss of biological diversity and even proposed a dismantling of both hydroelectric installations, this study aimed at proposing a counter-expertise. The authors present the river and its basin and both dams. While considering three different scenarios (maintaining works, alternative design of the equipment chain, and works dismantling for a totally opened river), they address various aspects and issues: actors, representations and consultation, hydroelectric production, condition and safety of works, sediment management and draining, water quality and drinking water supply, floods, quality of environments and ecological continuity, and socio-economics of the territory