The project aims to restore the ecological continuity of the Eyrieux by removing 2 weirs and renaturating 70m of the river in its original bed.
The Eyrieux Valley is a land of contrasts, from its source at an altitude of 1,105 metres to its confluence with the Rhône River at 93 metres, south of Valence. The upper basin is influenced by mountain conditions, while the lower valley belongs to Mediterranean lands.
Along its 80 km course, the Eyrieux offers a variety of landscapes, from the St Agrève plateau with its waterlogged wetlands to the narrow rocky gorges with their steep gradients. It is the second-largest watershed in the Ardèche department, covering 853 km².
The upstream Eyrieux is typical of a high-quality salmon-farming zone, with brown trout being the target species. The white-clawed crayfish (Austropotamobius pallipes) has also been inventoried in the vicinity of the project, and the Eyrieux basin is one of the most heavily populated in France to date, with over 100 km of its length occupied. Other heritage species include the yellow-bellied toad, wetland azure, alpine newt, otter, and fine-bodied corduliidae.
| Project status | Live |
|---|---|
| Project type | Dam removal: demolition |
| Country | France |
| River | Eyrieux |
| Removal date | September - December 2025 |
| Km to be opened | 7 km |
| Focal species | Fario trout, white-footed crayfish |
| Organisation | European Rivers Network |
| Project website | Syndicat Mixte de l'Eyrieux à Crussol & ERN |
The steep slopes of the Eyrieux river network are marked by the presence of numerous obstacles, often linked to past human activities, such as mills, water intakes for agriculture, and hydroelectricity.
Two weirs, located around 100 metres apart, block the upstream Eyrieux in the commune of Saint-Agrève. They were originally constructed to supply water for “textile” activities, a mill, and a sawmill, but today these two water intakes are no longer in use. One of them diverts water from the Eyrieux into a canal and has no mechanism to ensure a minimum flow in the river at all times. The other directs water from the diverted Eyrieux towards the old mill, which has been converted into a dwelling, causing significant water infiltration into the building.
The owners of the structures have expressed their support for one of the proposed work scenarios, which would resolve the issue of compliance with the reserved flow and restore the ecological continuity of the Eyrieux.
Following a previous Programme-supported grant, the work will involve removing the two weirs and recreating the 70-metre linear stretch of the Eyrieux in its natural position at the bottom of the valley, in the section that had been diverted. This will contribute to the full restoration of the aquatic environment in this part of the upstream Eyrieux. In particular, it will enable the renaturation of the river’s morphology, habitats, and surroundings (riparian vegetation, open spaces, etc.).
Funded by
