The objective of the analysis was to characterize the lake sediments of an artificial lake in Rassina – Arezzo. The surveys have been carried out through Geoelectric, with floats to allow the electrodes to float at water level. Measuring the water electric conductivity and the lake bathymetry it has been possible to defining and removing the water body, during the data processing. The sections carried out have permitted to reconstruct with an excellent resolution the thickness of the lake sediments and to verify their impermeability.