One of the major problems associated with running the register of land and buildings (the cadastre) is determining the course of the boundaries of parcels covered with surface flowing waters. The collected record data should be up-to-date and reliable. These requirements also apply to parcels under flowing waters or located in their immediate vicinity. Determining the course of such boundaries may be based on the provisions of the Regulation on the register of land and buildings (until the course of these boundaries has been determined pursuant to the Act the Water Law). This publication presents technical aspects of determining a shoreline. The author analyzed possible methods to carry out the adjustment of the course of the boundaries of parcels under flowing waters, as well as of the adjacent land.