In 2018, the legal status of the Caspian Sea was clearly defined. Hence, the issue of sustainable development takes the centre stage. Regional legal regime of environmental protection may develop through the transfer of executive functions provided for in the intergovernmental convention and entrusted to the national authorities of the Caspian States to a single competent authority in order to improve their efficiency. The article is aimed at studying the issues of correlation between international legal rules on the Caspian Sea environmental protection and Russian national legislation in order to identify the optimal scope of executive functions that can be transferred to a regional intergovernmental organization, as well as to identify promising directions for further development of the applicable national legislation. The author shows that for a more efficient environmental protection of the Caspian region the Caspian states need a single regional intergovernmental body that coordinates their environmental activities, collects data and information on pollution on a centralized and timely basis, and regularly performs assessment of the Caspian region environment. Further, the author also shows the need for further development of applicable national legislation in the context of the concept of integrated coastal management.