This Nature Park was declared the fifth Croatian wetland of the international importance twenty years after The Ramsar Convention added first Croatian areas to its list.
After satisfying six out of nine criteria of the oldest international agreement concluded entirely to protect ecosystem, at February 2nd 2013 Nature Park was listed in the world's important wetland as the biggest natural, permanent water body of Croatia. It is of the tremendous importance to endangered European bird species. To present the centre of biological diversity of wider region, this area along with the Neretva Delta is the largest swamp area of the Adriatic east coast. It has international importance due to specific geographical and climate location which sustains wet and rare habitats, marshes, flooded meadows and winter habitats for birds.
Value of this immense floodplain overgrown with reeds was recognized in 1983 when the northwest part was declared reservation of ornithology and the whole Vrana Lake also declared important European bird area. Many bird species, 60% of total Croatian bird fauna found their home at the lake. Even though Croatia's rich biological diversity points to the preservation and quality of natural environment, there is a fact that 136 species of birds are endangered on global, European and national level, while for some species like Purple Heron and Pygmy Cormorant this area is the only nesting habitat left in Croatia.