Baćina Lakes are located in the immediate vicinity of the Adriatic Sea and, despite the permeable karst terrain, are filled with fresh water. The bottom of the lake is located below the sea level, while the surface of the lake itself is above. For that reason, Baćina lakes are considered cryptodepressions. Within the lake there are six freshwater karst lakes. In this master thesis, based on available data, the water regime of these lakes is analyzed by observing hydrological stations on Lake Šipak and the overflow of the source Klokun in Baćina, as well as on the watercourse Matica Vrgorska, which is connected by a tunnel to Lakes Staševica and Krotuša. The recieved inputs and available data taken from the official website of the Croatian Meteorological and Hydrological Service were used as a basis. The paper thus uses the available data related to daily, monthly and annual discharges at the water courses of Matica Vrgorska, Baćina Lakes and Klokun in the period from 1979 to 2020. The following data processing methodologies were used for data processing: correlation / regression analysis, homogeneity analysis, basic statistical data processing, course and trend analysis, and probability analysis of characteristic indicators.