Land covered by water is a special type of object in the register of land and buildings. It constitutes a separate usable land which covers: the land under internal sea water, the land under flowing surface water, and the land under still surface water. These examples of usable land do not exhaust the list of all the territories occupied by water. Agricultural land also includes land under ponds and land under ditches. The Water Law provides for a special procedure for determining the boundaries between the land under water and the neighboring land, different from the proceedings regulated by the Geodetic and Cartographic Law. However, in practice, the implementation of this procedure encounters problems due to imprecise regulations.This article analyzes in detail three proceedings regarding the delimitation of land covered with flowing surface water from neighboring land. In each of the cases, the proceedings are implemented in a slightly different manner. This allowed to identify gaps in the legislation regulating the determination of a shoreline, especially in the field of surveying. ...