It empties into the Black Sea in a small homonymous bay to the west of Cape Saint Demetrius. Near its mouth there is a long and wide liman separated from the sea by sandspits, which is navigable for small vessels. Ropotamo's drainage basin spans a territory of 249 km². It borders the basins of the rivers Izvorska that empties into Lake Mandrensko to the north-west, Veleka to the south-west and Dyavolska reka to the south and south-east. The river has predominantly rain feed with high water in winter (January–February) and low water in autumn (August). The average annual flow is 1.31 m3/s at the village of Veselie. Most of the river valley is covered in dense riparian forests of oak, ash, elm, hornbeam, etc. The lower course hosts abundant populations of European white water lily ("Nymphaea alba") and a number of rare plant and animal species. To protect these ecosystems in 1940 the authorities established the Ropotamo Reserve, which was designated a Ramsar site in 1975 as part of the Ropotamo Complex that also includes the swamps Alepu, Arkutino and several smaller protected areas. In the lower course there are rock formations, such as the Lion's Head, small caves, and the highest dune in the Balkans. The most important mammal species are red deer, fallow deer, roe deer, wild boar, grey wolf, red fox and golden jackal. The largest birds of prey are the white-tailed eagles with a wing-span of over two meters, and the Eurasian eagle-owl. The river is located on the Via Pontica bird migratory route. There are about 50 fish species, such as flathead grey mullet, big-scale sand smelt, European eel, round goby, Caucasian dwarf goby, as well as abundant populations of European pond turtle. Hillside Airport  Hillside Airport is a public use airport located four nautical miles (7 km) northeast of the central business district of Stilwell, a town in Johnson County, Kansas, United States. Hillside Airport covers an area of at an elevation of 1,025 feet (312 m) above mean sea level. It has one runway designated 17/35 with a turf and gravel surface measuring is 2,000 by 56 feet (610 x 17 m). For the 12-month period ending May 31, 2007, the airport had 2,000 general aviation aircraft operations, an average of 166 per month.