Existing Solutions

River continuity, Restoration, migratory fish, habitats, hydromorphology

technical

Removal of a dam (built in 1920) in the context of a long term management plan of the river Loire, to improve the continuity and to enhance fish migration potential. The dam belonged at first to a paper mill factory, then after to the French electricity supply company (EdF).

The solution was implemented on the river Vienne, an tributary of River Loire. The dam was situated after the confluence of the river with the Creuse, another major tributary. These  sub-basins historically attracted salmon, shad, sea lamprey and eels.

Leaders of the programme are:

- the French National Agency for Water and Aquatic Environments (ONEMA)

- the Water Agency Loire-Bretagne

Other partners include:

French State, EdF, Plan Loire Grandeur Nature staff, Logrami Association, Conseil Supérieur de la Pêche  and the county Fishing Federation.

The Plan Loire Grandeur Nature adopted in January 1994 planned the removal of the dam,  inspired by a previous removal of St Etienne de Vigan dam decided following the campaign “living Loire” (“Loire Vivante”). Demolition works have started in mid-June 1998 and were completed by the end of 1999.

The dam, 3.8 meters high, situated 250 m after the confluence of the Creuse with the Vienne created a blockage in both these basins: water was stagnant for 8 km on the Creuse and 7 km on the Vienne. Since the building of the dam, not a salmon or a shad had been caught upstream the dam. Remedial efforts had been made by the successive installation of 3 fish-passes, with little effect.

The removal of the Maisons-rouges dam was the first major dam removal in France.
The results are positive for the assessed components. Habitats have diversified, accumulated sediments have been removed, flora development has been measured, positive landscape changes have been obtained. A biological level, convincing results in term of recolonisation have been obtained from 1999 and the following year.

Monitoring operations were carried out in 1995,updated in 1998 prior to the removal operation. Major monitoring was conducted each year from 1999 (end of works) to 2005, and then in 2009.
Components of monitoring: hydromorphology and sedimentology, macro invertebrates, large migratory fish, riparian vegetation.

Who can be most interested?: local authorities, national state, administration looking to dismantle a major work in a river channel for ther restoration of continuity.

It is necessary to have a strong involvement of all partners for a long period.
The solution is better promoted in the context of a global basin management plan
The investement in preliminary studies and the cost of operation is high , cost for this little dam was in the range of 2.5 million Euros.

There is a national strategy, supported by ONEMA and the 6 French Water  Agencies, to enhance continuity of rivers.

Onema – Délégation interrégionale: dr4@onema.fr
Logrami Vienne: http://www.logrami.fr
Onema – Head office: josee.peress@onema.fr
Agence eau Loire Bretagne: andre-francois.boschet@eau-loire-bretagne.fr

The removal of the Maisons-Rouges dam, which was one of the first examples of major dam removal in France, received extensive media coverage.
This large-scale project was featured in local and national articles and in a video.