Modern technologies give an opportunity to create a large number of bathymetric maps, but less of them have been focused on processing the water depth data in order to study and estimate the subterranean sources of water object supply. This study aims to create a mechanism for estimating the productivity of subterranean sources of lakes water supply, based on bathymetric survey data. Lake Svitiaz was chosen as the study site as the deepest closed lake of natural origin in Ukraine with an area of 2500 ha and a maximum depth of 58.4 m. To get depth data, ground-based measurements were conducted using an echosounder