Lissos (or Filiouris) is a large river in Thrace, Greece.
The springs of Lissos are located at the mountains of Eastern Rhodope, at the hills of Demir Chal, near the borders of the Prefectures of Rodopi and Evros, while a second main water body that contributes to Lissos, springs from the east, near Leptokarya of Evros Prefecture.
The river flows through the mountains of Rodopi, from northeast to southwest, and recharges into the Thracian Sea. The total length is about 70 km, with the main river running at 45 km, while the catchment area extends to 1,490 km2.
The Lissos catchment area is of particular research interest, with increased monitoring needs, both for the extent and intensity of the pressures it receives and the lack of available knowledge/scientific research. As it flows into bathing shores and protected coastal areas, the protection regime of the region is of high importance. It is a water body with habitat fragmentation since the former natural habitats, such as forests and fens have almost disappeared and were replaced from crops, changing the main characteristics of the river entirely. Some parts have been designated as Heavily Modified Water Bodies (HMWB); specifically, it includes six natural water bodies and three HMWB’s with estuaries on the east coast.
Due to the intense agricultural activity in the area, it receives nitrate pollution, as well as high organic load, since it is a recipient of industrial and municipal waste water (industry, Waste Water Treatment Plant, landfill). Additionally, it shows unique ecological interest because it is the habitat for many species of wild animals. The Lissos river basin is one of the most important areas in Greece for birds and especially for the impressive vultures.
