The project aims to restore ecological continuity at the site of a former mill on the Malencourie River by removing the pond and restoring the original riverbed, allowing for the free passage of water, sediment, and aquatic species, and sustainably improving the river’s ecological quality.
The project is located on the Haute Dronne, within a Natura 2000 site in the Dordogne department in France – specifically on the Malencourie, one of its main tributaries. This area, designated as a UNESCO Biosphere Reserve, holds significant ecological value, particularly at the confluence of the Malencourie and the Dronne, where the presence of the freshwater pearl mussel has been confirmed. The Dronne hosts one of the largest known populations of this species in France.
Tributaries like the Malencourie play a key role as spawning and refuge habitats for brown trout, the host fish essential to the mussel’s life cycle. These cool, well-oxygenated watercourses are vital climate refuges, especially during low-flow periods, making them particularly important in the context of climate change.
| Project status | Live |
|---|---|
| Project type | Dam removal: demolition |
| Country | France |
| River | Malencourie |
| Removal date | Autumn 2025 - Summer 2026 |
| Km to be opened | 4 km |
| Focal species | Brown trout, pearl mussel, lamprey gliding, bullhead |
| Organisation | Périgord Limousin Regional Natural Park & European Rivers Network (ERN) |
| Website | PNR Périgord Limousin & ERN - Open Rivers |
Historical development of weirs and ponds has led to significant habitat fragmentation, disrupting the natural flow and hindering the movement of aquatic species. These infrastructures also contribute to thermal pollution: artificial impoundments cause elevated water temperatures, especially during summer, with peaks exceeding 24 °C. Such thermal stress can be fatal to cold-water species like the pearl mussel and brown trout.
This dam represents the last upstream barrier along the main course. Reopening this barrier will restore the watercourse up to the source of the Malencourie. In the past, during a LIFE project, another structure was removed (the Paugnac reservoir) at the downstream part of the Malencourie (confluence with the Dronne). After this new removal, the river will be fully reconnected along the entire length of its main course.
The Dronne River basin holds high ecological value, particularly due to the presence of heritage species. Among them, the freshwater pearl mussel (Margaritifera margaritifera), critically endangered, is still found in certain stretches of the river. Its tributaries, such as the Malencourie, also provide suitable habitats for brown trout (Salmo trutta fario), another sensitive species.
The project aims to restore ecological functionality at the Maziéras mill, a crucial step for the watercourse. The project will restore habitat connectivity, which is essential for the migration, reproduction, and survival of native species, including protected and indicator species. Restoring ecological continuity will also help improve water quality and the overall ecological functioning of the river system. It will contribute significantly to the resilience of the watershed, especially in the face of increasing pressures such as climate change and land-use modifications.
Ultimately, this project will reinstate a vital ecological function of the watercourse, supporting the health and biodiversity of the entire watershed and its ecosystems. It serves as a model for sustainable water management and river restoration in the region.
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