The operation concerns a study on the biodiversity potential of hillside reservoirs. As part of this study, naturalistic monitoring will be carried out over 5 years, on three reservoirs located in the municipalities of Villefranche d'Allier, Tronget and Theil. The Le Theil site will be built in 2024. It will make it possible to carry out an initial state and will serve as a demonstration site to better understand the impacts of the construction of a hill reservoir. As a result of increasingly intense pressures on water resources, the number of projects for the creation of reservoirs is likely to increase. This is why the association Symbiose Allier wants to carry out a study that aims to improve knowledge about the environmental impact of these reservoirs on local biodiversity and in particular that of wetlands.