Restoration of the Neez river in Jurançon, France

Introduction

The Neez is the first tributary of the Gave de Pau river encountered by the Gave de Pau salmon during their migration to spawning grounds. The project team has identified a major problem with the accessibility of this river for migratory fish, particularly Atlantic salmon.

This project will free up 8 km of river upstream on the Neez River by removing two dams: Bernet Dam and Oudoul Dam. This project is being carried out in an urban setting, which presents complex technical and social challenges. It goes beyond simply facilitating the upstream migration of fish; it prompts reflection on the relationship between residents and the river.

Project context and opportunity

In recent years, for several years in a row, juvenile salmon have been observed in the lower reaches of this river. Currently, only a 1.7 km stretch downstream is accessible to migratory fish. Two disused dams (Oudoul and Bernet Dams), located very close to each other, completely block the colonisation of the upstream section until the next obstacle, 8 km upstream (a partially passable obstacle; for salmon, the next real obstacle is 9 km upstream).

The upstream section of these two dams presents significantly greater potential than the currently colonised downstream section, in terms of available habitat area for large migratory salmonids (both for adult reproduction and juvenile rearing). This point has been specifically studied by the MIGRADOUR association: currently, only 10% of this river’s potential is accessible.

Furthermore, the river’s hydromorphology is severely disrupted by these two obstacles (liquid and solid sedimentation), resulting in reduced current velocity and siltation of the riverbed.

Project aims

The project team has high hopes for this project to:

• allow Atlantic salmon and other migratory fish to colonise the upper reaches of the Neez River;
• raise awareness about the return of this highly symbolic species to the heart of an urban area. This is an important point that caught the attention of the president of the Pau metropolitan area;
• demonstrate to other project leaders that rivers can be restored even in urban areas, where many fear the consequences;
• rekindle residents’ appreciation for a more natural river in an urban setting, bringing them closer to this ecosystem.