The Saint-Michel Dam is a former hydraulic factory built in the minor bed of the Somme River. Abandoned, a cofferboard device was set up to prevent the passage of water in the factory. The building impedes flood flow and ecological and sedimentary continuity. The Somme River is home to an important aquatic biodiversity (RAMSAR site) and is recognised as a watercourse for highly migratory amphibhals (fish living both in the river and at sea). These include aloses, eels, salmon, sea trout and sea lampreys. These species are now, for some, threatened with extinction. The development work consists of three phases: —1- the Saint-Michel factory, owned by the State registered in the Referential des Obstacles à l’ Ecoulement (ROE) 21344 (work 2019, under delegated work control Agence de l’eau Artois-Picardie -AEAP-), -2- the Bras du Pendu, departmental property (work 2019, under delegated work AEAP) and -3- the Barrage du Pendu, departmental property (works carried out in 2013 by the Department of the Somme). Phases 1 and 2 are the subject of this application for European aid. The aim of the work is to reconcile the evacuation of floods and restore the functionalities of the Somme River on this area and to limit the ecological impact of a major obstacle to the migration of the heritage species of this river, in particular the eel.