Structure on a watercourse means a transverse obstruction such as a dam, a small reservoir or pond, a weir, a level preventing the natural migration of aquatic animals, or a structure used to observe the condition of surface waters located in the watercourse channel or on land adjacent to the watercourse channel. The registration of objects on watercourses is kept and updated by the Basin state enterprises within the framework of the operational information system (ISYPO). The scope of published data is determined by the current legislation.