Tundzha/Tundja/Tunca Sub-basinn

Bulgaria and Turkey share the sub-basin of the Tundzha/Tundja/Tunca, which has its source in the Stara Planina Mountain (Bulgaria), and flows into the Meriç River. The Fishera River is a tributary shared by Bulgaria and Turkey.

Pressures, impacts and responses

There are 264 dams located in the Bulgarian part. The larger dams/reservoirs serve multiple purposes: energy production, irrigation, industrial and drinking water supply. There are four hydropower stations, and three thermal power plants.

Eutrophication in the reservoirs of the large dams in Bulgaria as well as nitrate pollution of groundwater, in the middle part of the basin, has been observed. Among pollution sources, wastewater discharge from municipalities and industry ranks in the first place, followed by diffuse pollution (78% from agriculture). Measures for the improvement of the situation are being taken, e.g. wastewater treatment plants are being constructed. The sewerage system currently serves 31% of the population in the Bulgarian part, while wastewater treatment plants treat 11% of the urban wastewaters. There are six waste disposal sites in the Bulgarian part.