The Saint Andoche Dam in Autun is the last obstacle to the migration of amphihalin migratory fish over the Arroux River, including preventing access to upstream rivers: the Ternin, the Drée and the Arroux upstream. The restoration of ecological continuity at the level of this work complies with provisions 9A of the SDAGE 2016-2021, and the Arroux is identified in the list of axes for these species (Grande Alose, Atlantic Salmon, Anguille, Sea Trout and Marine Lamprey) as well as the Ternin (Anguille, Atlantic Salmon). The Saint Andoche dam on the Arroux is one of the 13 priority works identified in the Management Plan for Migratory Fishes in the Loire Basin (PLAGEPOMI) and is a priority work Grenelle, concerned by the Order of 2 January 1986 (Arroux d’Autun at its confluence with the Loire) listed in list 2. The operation consists of carrying out scrapping works on the work of Saint Andoche with the creation of a cut-off in the foundations. Development and ecological restoration of the riverbed will be carried out to maintain optimum flow conditions in this urban area.