Weirs and ecological continuity

Many obstacles, weirs or dams, were long-ago built on the waterways to draw from their hydraulic power. Most of them are no longer used and still hinder the natural transportation of sediments from the river and the movement of fish.
Through lack of maintenance, these run a great risk of destabilising neighbouring infrastructures. Knowledge of how waterways work has also significantly improved, encouraging their managers to work towards a more natural operation of waterways, by installing or dismantling unused weirs.