Iskar River
The Iskar River has a length of 368 kilometers and makes the longest river solely in Bulgarian territory. The Iskar is the only river to take its source from southern Bulgaria and cross the Balkan Mountains to flow into the Danube. The Iskar flows through seven provinces of Bulgaria: the capital city of Sofia, Sofia Province, Pernik Province, Vratsa Province, Pleven Province and Lovech Province. The Iskar river is created by three rivers, the Cherni /black/ Iskar, Beli /white/ Iskar and Levi /left/ Iskar, which is known under the collective name Iskrove, with the source being accepted to be the Prav /straight/ Iskar, a tributary of the Cherni Iskar. After descending from the north slopes of Rila Mountain, it fills the Iskar Reservoir – the largest in Bulgaria and the Lake Pancharevo.
The Iskar River runs near Sofia and passes through a rocky gorge in the Balkan Mountains /Stara Planina/. Iskar is the oldest river in the Balkans, and also the only one to have preserved its original direction despite the significant geological changes in later stages. The construction of 9 mini hydroelectric power-stations (one of which is already in operation) has been carried out in the middle part of the Iskar river.