A 36-meter-high concrete wall sealed off a Norman river for almost 100 years, blocking the natural migration of Atlantic salmon. In 2020, the wall—part of the Vezins Dam—was removed in a major effort that became the largest dam removal project in Europe. This action allowed salmon to swim upstream along the Sélune River to its source, something that had not happened since the 1930s. The Vezins Dam, built between 1929 and 1932, was dismantled in 2019-2020. A second dam, the Roche-qui-Boit, was fully removed by the end of 2022, completing the largest dam removal operation of its kind in Europe. On November 8, 2023, INRAE, a French research organization, officially confirmed the return of Atlantic salmon to the Sélune, with young salmon born directly upstream in a free-flowing river. This marked a significant step in restoring the river's ecological balance. The Vezins Dam was not just a simple structure. Standing 36 meters high, it used 2,000 tons of iron, 10,000 tons of cement, and over 25,000 cubic meters of stone. Combined with the Roche-qui-Boit Dam, it formed a nearly impassable barrier for migratory fish, preventing salmon from reaching their historical spawning grounds. For nearly 90 years, these two dams transformed the Sélune from a thriving river into a fragmented ecosystem, cutting it off from its upper reaches and the biodiversity that once passed through it. The removal of the Vezins Dam began in 2019 and was completed in 2020, while the Roche-qui-Boit Dam was dismantled by the end of 2022. The main challenge was not the actual demolition but managing the 2 million cubic meters of silt that had built up in the Vezins reservoir over decades, along with additional silt from the riverbed and its tributaries. The project received financial support from the Seine-Normandie Water Agency, which contributed 56 million euros. By 2021, the Ministry of Ecological Transition had already announced that 90 kilometers of the river would be reopened to restore biodiversity, a prediction that proved accurate by 2023. The return of Atlantic salmon to the Sélune is not the only positive outcome of this project. The European eel and the sea lamprey, both species that rely on migration between the sea and rivers, also benefit from the restored watercourse. The Sélune Program, a scientific initiative monitoring biodiversity and water quality, tracks the river's ecological recovery in real time. Researchers estimate that the Sélune could eventually support up to 5,000 Atlantic salmon, a population with valuable genetic significance for the French Atlantic coastline. During the autumn season, when salmon migrate upstream to spawn, the return of these fish represents a crucial step in rebuilding a population that had once been on the brink of local extinction.