Assessing the feasibility of removing six barriers on the Semois River, opening approximately 89 km of the river.
The Semois River (Meuse basin) in southern Wallonia, Belgium, spans 200 km, starting in urban areas with moderate ecological status before passing through agricultural lands and the Ardenne Forest with generally good ecological conditions. The basin supports outdoor activities, heritage tourism, and recreational fishing, hosting migratory fish species like the European eel, brown trout, pike, and grayling. The Semois is also home to the thick-shelled river mussel, which is fully protected in Wallonia.
Designated as the Semois Valley National Park in 2022, efforts focus on habitat restoration and reconnecting habitats on a landscape scale, crucial for recolonizing species like the European Otter and European Lynx. The park’s significance is highlighted by its coverage of N2000 areas, emphasising its ecological importance and potential for sustainable tourism.
| Project status | Completed |
|---|---|
| Project type | Dam removal: pre-demolition |
| Country | Belgium |
| River | Semois |
| Focal species | brown trout, eel, pike, grayling, thick shelled river mussel |
| Organisation | Contrat de Rivière Semois-Chiers |
| Website | Semois Parc National |
Before 2022, Wallonia had never seen a national park. The Semois Valley National Park is one of the first, with another declared simultaneously. This presents a unique opportunity, with over 600 km of streams, rivers, and the Semois at its heart. The park provides a new framework, placing nature at the forefront of decision-making while striving to ensure access for all, focusing on sustainable tourism and slow mobility.
Despite the Semois River being generally in good ecological health, challenges persist, including the impacts of global changes, invasive species, and river fragmentation. The national park offers a chance to innovate, particularly in river restoration efforts, and the project team is excited to lead this initiative.
The project focuses on assessing the feasibility of removing six barriers on the Semois River mainstem, opening approximately 89 km of rivers, about half its length. The regional government has prioritised restoring fish migration routes, identifying the Semois River as a key area. Despite the existence of the Water Code, which promotes free movement for fish, its implementation remains incomplete.
The project aims to engage authorities and all stakeholders, including the public, to emphasize the importance of free-flowing rivers for nature and people. Currently, over 200 barriers in the Semois catchment are being assessed, primarily small culverts, poorly designed bridges, and weirs (<3m), with high potential for removal. While the National Park facilitates development and restoration efforts, current funding for dam removal falls short of what’s needed to restore the Semois and its tributaries fully.
The feasibility studies will include hydraulic modelling, flood risk, sedimentary processes, fish community and mussel assessment, and concertation with stakeholders and local communities. For some of the barriers, heritage importance is a concern that needs to be addressed.
The Semois River project has achieved significant progress towards preparing the largest dam removal initiative ever undertaken in Belgium. Comprehensive fieldwork was completed in late 2024, encompassing hydromorphological surveys, sediment assessments, habitat inventories, and detailed evaluations of ecological risks and opportunities. Collaboration with water managers, fisheries experts, and Natura 2000 authorities has strengthened the project’s technical foundations and reinforced a shared understanding of the river system.
Overall, the project has established a solid technical and collaborative foundation. The evidence compiled to date provides a clearer understanding of the opportunities and challenges associated with barrier removal, without presuming the outcome of future decisions. As managers, scientists, and community representatives continue to engage with the results, the Semois initiative now stands as a strong reference point for large-scale river restoration in Belgium, while recognising that the timetable and feasibility of any eventual dam removal will depend on future political, social, and administrative considerations.
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