Background The lower reaches of the Aragón and Arga rivers forms one of the Sites of Community Importance (SCI) included in the Natura 2000 network. The area’s importance is mainly due to the presence of Mediterranean river forest habitats (Mediterranean poplar and willow forests) and species such as European mink (Mustela lutreola), otter (Lutra lutra), European turtle (Emys orbicularis) and night heron (Nycticorax nycticorax). In the past, dikes and breakwater defences were built to defend agricultural and forestry plantations along the rivers’ floodplains, and the Arga River was canalised to protect downstream towns from floods. These defence infrastructures have diminished the dynamics of these two rivers, resulting in a decrease in natural habitats and a reduction in biodiversity. The degradation of the fluvial ecosystem is especially problematic for the European mink. The project area hosts a fifth of the species population in Navarra and two-thirds of the Iberian population; hence the importance of restoring the river ecosystems of the lower reaches of these two rivers for the global strategy of the species conservation. Objectives This project aims to significantly enhance the biodiversity of the lower reaches of the Aragón and Arga Rivers. In particular, it aims to improve the conservation status of European mink (Mustela lutreola) by restoring the fluvial ecosystems on which the species depends. This will guarantee the preservation of the species in the area and promote it as a source of individuals for the recovery of neighbouring populations. The project will implement the ‘fluvial territory’ concept as a way of preserving biodiversity and obtaining good ecological status, while also promoting public interest and awareness. By restoring the floodplains and the natural habitats on which the mink depends, the project will contribute to EU water, conservation and flood management objectives and serve as a model for Mediterranean river management. Expected results: The project is expected to achieve an integral improvement of the fluvial ecosystem that will lead to the recovery and increase in population of the European mink, together with a decrease in its main threats. Oxbow lakes, wetlands, floodplains, river forests and river beds will be restored as part of the objective of improving the carrying capacity of the area for the target species. The project will also seek to promote a more positive public attitude to nature, the fluvial territory and biodiversity conservation.