This project aims to remove the Horta Fialho weir, thereby restoring 2.34 km of the Oeiras River, the riparian vegetation in the intervention area, improving the habitat for native fish and endangered mussel species and the overall ecological status of the Oeiras River.
The Oeiras River is located in the western part of the Algarve, being one of the tributaries of the Arade River. It flows through various rural areas, passing through agricultural zones and small towns before joining the Arade River. It is a typical intermittent Mediterranean stream, hosting several native and endangered species, including three freshwater mussels (Unio tumidiformis, Anodonta anatina, Unio delphinus), their host Squalius spp., and the migratory eel (Anguilla anguilla). The area is also home to iconic mammals, such as the Iberian lynx (Lynx pardinus) and the otter (Lutra lutra).
| Project status | Live |
|---|---|
| Project type | Dam removal: demolition |
| Country | Portugal |
| River | Oeiras |
| Km to be opened | 2.34 km |
| Focal species | Swollen river mussel (Unio tumidiformis), two other native mussel species (Duck mussel: Anodonta anatina; Dolphin freshwater mussel: Unio delphinus), several chub species (Squalius spp.), Southern Iberian barbel (Luciobarbus sclateri), Iberian arched-mouth nase (Iberochondrostoma lemmingii), Iberian lynx (Lynx pardinus), Otter (Lutra lutra) |
| Removal date | Predicted to be before or after fish reproductive migrations (early spring or late summer 2025) |
| Organisation | ANP/WWF |
| Project website | ANP/WWF |
The goal of this project is to remove the Horta do Fialho weir, thus restoring 2.34 km of the River Oeiras connectivity (≈ 2% of its length) and improving the ecological status of this river section closest to the weir from “Poor” to “Moderate”. This objective will also be accomplished following the restoration of the riparian vegetation in the area adjacent to the barrier, improving the habitat for native fish and the endangered mussel Unio tumidiformis.
This removal will also pave the way for eight removals, which would fully restore the connectivity of the Oeiras River (143.3 km), significantly contributing to improve the ecological status and promote the conservation of biodiversity in the Oeiras River.
The project will raise awareness of the benefits of dam removal among the local community, children, and the public through communication materials, environmental education, and advocacy activities, at local, regional, and national levels. Opportunities will be explored to scale up the project to the Vascão River, which has already been targeted by another project (recently submitted to WWF’s “Rivers2Restore” initiative).
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