Lescoude Culvert, France

The Lescoude Culvert removal will restore the ecological functions of the Bosdapous River.

Introduction

The Bosdapous is a small,  4.5 km long river surrounded by a watershed mainly made up of forest. It’s a well-preserved tributary of the Gave d’Aspe River and rises to an altitude of 900m. Its good water quality hosts a population of brown trout, European eel and white-clawed crayfish. This stream has a very important role for these species, which are also present in the Gave d’Aspe (the main river in the valley). Trout go there every year to reproduce. The populations of crayfish, which are becoming increasingly rare, also need to be connected to facilitate their resilience to crises.

At a glance

Project typeDam removal (demolition)
Project statusComplete
Removal dateOctober 2022
CountryFrance
RiverBosdapous
Km opened4
Key habitatsSpawning habitat for salmonids
Focal speciesBrown trout, European eel and white-clawed crayfish
Websitehttps://www.federation-peche64.fr/

Project context and opportunity

Many projects have recently been carried out on the main river but not on small tributaries like the Bosdapous, affecting the circulation of fish (and of all aquatic organisms in general). For 20 years, an obstacle located 500m from the confluence with the Gave d’Aspe prevented the circulation of fish and crayfish populations upstream. It was a culvert that allowed passage to an old sheepfold. For these reasons, Federation Peche 64 has been in dialogue with the owner of the Lescoude Culvert, who favoured removing it. Until 2020, the project could not succeed due to financial reasons.

Project aims

The project team removed the culvert and replaced it with a small bridge without influencing the river. This opened 4 km of river and reconnected the Bosdapous to the Gave d’Aspe River. Trout spawners will now be able to access the Bosdapous excellent upstream spawnings grounds, and eels will also be able to colonise new territories.

Project achievements

The project has been successfully completed, achieving the planned goal of completely removing the river obstacle. Despite a slight delay in the schedule, a small bridge without support in the riverbed was successfully constructed. Removing the obstacle has allowed fish and crayfish to move freely in the river, fully reconnecting it to the main river, Gave d’Aspe, and reopening 4 km of river. This restoration has enabled trout spawners to access the excellent upstream spawning grounds of Bosdapous, and eels can now colonize new territories, ultimately restoring the ecological functions of the Bosdapous.

Partners

République Française