Preparing weir removals on the Vascão & Odeleite rivers

Introduction

The Algarve is the most Southern and driest region of Portugal. The Vascão River is part of a national Protected Area (Guadiana Valley) and is a Site of Community Importance (Natura 2000), and a Ramsar site, being considered the biggest river without artificial interruptions such as dams or reservoirs in Portugal. The Odeleite River is partially within Caldeirão SCI and not far from the same national Protected Area (Guadiana Valley) and a Ramsar site (Castro Marim salt marshes). The landscape is mostly characterized by Mediterranean scrubland and very low population density.

Numerous archaeological remains from the Roman and Islamic periods are found in the area surrounding the Vascão River. Crucially, these two rivers host one of the few, remnant populations of the Spanish minnowcarp – the most endangered non-migratory fish species in Portuguese freshwaters, endemic to the Guadiana river basin – as well as other threatened fish species, the migratory European eel and sea lamprey, as well as several species of riparian birds, and iconic mammals such as the fish-eating otter and the endemic and endangered Iberian lynx.

Project context and opportunity

Most of the barriers described in this project were prioritised for removal by a ministerial report and/or by the ICNF, the national authority for Nature and Forests Conservation. One of these barriers on the Vascão River was recently removed by the ICNF itself. Most (if not all) of these barriers appear to belong to the Municipality of Alcoutim, which is already partnering with ANP/WWF on the Galaxes weir removal.

This project is intended to significantly scale up the operations realised in Galaxes Weir Removal project by aiming to remove two additional barriers in the same river (Odeleite River), and 12 weirs on the Vascão River – the two rivers that together host the only surviving populations in Portugal of the most endangered, non-migratory freshwater fish species, the Spanish minnowcarp (globally endangered).

These removals have the potential to restore 93 kms of free flowing river and significantly improve the habitat for – and therefore help conserve – the Spanish minnowcarp. The removals will also benefit the critically-endangered European eel and give a boost to other native species of conservation concern, including several fish species, as well as iconic mammals, such as the Iberian lynx and the otter.

Project aims

This project aims to scale up the single barrier removal targeted by the project Galaxes Weir Removal, preparing the path for further removals in the same river (Odeleite River), as well as additional removals in the nearby Vascão River. These removals would help to build stronger relationships with decision makers in the area and at national level and possibly gain commitments from them for future removal projects, both locally and nationally.

Overall, the project has the potential to restore the fluvial connectivity of more than 90 km of rivers, which would considerably contribute to the conservation of the endangered Spanish minnowcarp and the migratory European eel and Sea lamprey. The removals would also improve recreational activities in the area including fishing, hiking, and other traditional activities, which in turn would help developing tourism associated with the Natural Park of Guadiana Valley, as well as coastal tourist resorts in the Algarve. Also, by restoring the fluvial continuity, and in turn allowing ecological conditions for healthier fish populations, the removals would benefit local fishermen and the economy related to the consumption of freshwater fish, which are appreciated in local gastronomy.

The project will allow research visits to the barriers, confirmation of their owners, studies on the feasibility of removing all the barriers, meetings with local community and the Municipality of Alcoutim to discuss the removals, securing the necessary authorisations, contracting a construction company to prepare demolition and river design plans and provide invoice estimates, application for funding the removals, and efforts to secure co-funding from existing legislation or strategies.

Project achievements

The project, led by ANP/WWF, aimed to facilitate the removal of 12 weirs on the Vascão River and 2 on the Odeleite River, potentially restoring 93 km of river connectivity. A total of 14 barriers on the Vascão and 3 on the Odeleite were characterised and their data incorporated into the Amber Barrier Tracker app, contributing to barrier inventory and removal planning.

The project has also improved community awareness and collaboration among stakeholders. In-person meetings with stakeholders and local communities, combined with targeted environmental education sessions, highlighted the benefits of healthy rivers. Two sessions held in the Alcoutim Municipality, in June 2024, educated students and community members on the ecological importance of free-flowing rivers. These sessions included a presentation from the Institute for Nature Conservation and Forests (ICNF), reinforcing the importance of collaborative efforts.

ANP/WWF utilised innovative communication tools, including a Pop-up Book and Memory Cards game, to engage the public on the benefits of river restoration and dam removal. Additionally, the “Fish Motel” installation and campaign effectively illustrated the importance of ensuring free-flowing rivers for fish to reach their reproduction habitats.

Despite significant progress, the project faced community resistance to immediate barrier removals. Following advice from the Alcoutim Municipality, further removal projects were temporarily paused to allow for gradual acceptance of the benefits of the first planned removal, the Galaxes weir. Advocacy efforts were reprogrammed to foster understanding and support for dam removal among local stakeholders.

Through these efforts, ANP/WWF has laid a strong foundation for future barrier removals in the region while fostering awareness of the ecological and societal importance of restoring rivers to their natural flow. This project, completed in November 2024, represents a key step in building sustainable freshwater ecosystems in Portugal.