This study aimed to meet the request of the Institute for the Environment and Water Resources (Inema) for a hydrological study and volume calculation of Bonita lagoon, located in the rural region of Belmonte – BA. The hydrological study provides information on the characteristic flows that feed this water body. Together with the calculation of the current volume of water in the lagoon, information on the characteristic flows supports Inema in the evaluation of grant requests for surface capture in the lagoon.