Preparation of technical projects, obtaining administrative permits, and development of a public participation process for the demolition of the Molino de Abajo Dam on the Riato River (Community of Madrid, Spain).
The Riato or Puebla River is a mountain stream located in the Sierra Norte of Madrid, Spain. It belongs to the Tagus River basin and is a direct tributary of the Lozoya River, which in turn flows into the Jarama River. Although situated in Spain’s most populated province, the river runs through a sparsely inhabited area where the local economy is based on livestock farming, forestry, and tourism.
The river flows through a largely natural environment within the Natura 2000 Network (“Lozoya River Basin and Sierra Norte”) and the core area of the Sierra del Rincón Biosphere Reserve. It hosts species of high ecological value, such as brown trout (Salmo trutta) and several endemic fish species. Although its ecological status is good, the river’s connectivity is hindered by several obsolete barriers. This area is also part of the Riato and Puebla Rivers Natural River Reserve.
| Project status | Completed |
|---|---|
| Project type | Enabling others to remove dams |
| Country | Spain |
| River | Riato River |
| Focal species | Salmo trutta, Chondrostoma polylepis, Rutilus arcasii, Rutilus alburnoides, Cobitis taenia |
| Organisation | Asociación Ecologista de Jarama El Soto; with support of Madrid Ecologist Platform (ARBA, GRAMA, Jarama Vivo, Liberum Natura, and Asociación Ecologista de Jarama El Soto) |
| Website | elsoto.org |
The Riato or Puebla River flows through a well-preserved natural area in the Sierra Norte of Madrid. Despite its good ecological status, its continuity is severely affected by obsolete barriers, particularly the Molino de Abajo Dam – the largest and most impactful on river connectivity. This dam prevents the free movement of fish, sediments, and nutrients, disrupting river dynamics and habitat quality. Its removal will restore ecological connectivity along 20 km of river stretches, benefiting key species such as brown trout and several endemic fish.
The project aligns with Natura 2000 conservation goals and national river protection measures. By promoting the recovery of natural processes, it will strengthen ecosystem resilience and biodiversity. This preparatory phase will reduce uncertainties regarding ecological impacts and foster collaboration with stakeholders, paving the way for the successful removal of this obsolete structure.
The project aims to lay the groundwork for the removal of the abandoned Molino de Abajo Dam on the Riato or Puebla River – a key step toward restoring the ecological integrity of this mountain stream in the Sierra Norte of Madrid. By conducting technical studies, environmental assessments, and stakeholder engagement, the project will enable the future removal of this obsolete barrier, which currently blocks fish migration, sediment transport, and natural river dynamics along 20 km of river stretches.
Expected outcomes include obtaining the necessary permits, completing technical reports on dam structure and biodiversity, and fostering collaboration with local authorities, communities, and environmental organisations. Additionally, the project will raise public awareness about river conservation through communication and outreach activities.
Ultimately, this preparatory work will pave the way for reconnecting fragmented habitats, improving biodiversity, restoring hydromorphological processes, and enhancing the resilience of the Riato River – contributing to the objectives of the Natura 2000 Network, the Water Framework Directive, and Spain’s river conservation policies.
The project aimed to prepare the future removal of an obsolete 7.5 m high barrier, located in Robledillo de la Jara (Madrid), in order to restore the river’s ecological connectivity.
During its execution, contact was made with the Tagus River Basin Authority (CHT), which informed that the weir demolition was already included in a project financed by the PRTR. This scenario transformed the project from a pre-demolition (A2) to an enabling others to remove dam (B1) project, achieving the effective removal of the barrier in May 2026.
Achievements:
Ichthyological study that complemented the administration’s previous work, improving the ecological knowledge.
Drafting of a technical project focused on minimising damage during demolition and managing waste.
Active involvement of part of the local population in participation activities.
Key impacts:
Restoration of river continuity along 20 km of the river.
Facilitation of movement for species of high biological value (Salmo trutta, Chondrostoma polylepis, Rutilus arcasii, Rutilus alburnoides and Cobitis taenia).
Natural transport of sediments and nutrients.
Recovery of priority riparian habitats (habitat 91E0 and habitat 92A0).
Collaboration with the CHT and citizen participation have ensured that the weir removal is not merely an infrastructure intervention, but a true ecological and social restoration, bringing forward the project’s ultimate objective.
Funded by
