Good co-operation in environmental planning and especially in the field of natural disaster protection is essential for a carefree life of cross-border communities. In order to facilitate the everyday communication of the closely co-operating services, the project partners compiled a bilingual lexicon of water management terminology to be used for jointly implemented assignments, especially those of the permanent Hungarian-Croatian Water Management Commission. This helpful tool will be used to support the joint efforts, meetings, developments and projects along the river-border.