The river Bug rises in the Carpathian Mountains in the Lviv region (Ukraine). The total area of the basin is 39,420 Km2. More than 20% of the catchment area is situated in Ukraine, nearly 30% in Belarus and about 50% in Poland. The total length is 772 km, 185 km of which forms the border between Ukraine and Poland, and 178 km forms the border between Belarus and Poland. The river is the main tributary of the river Narew (Poland). In the lower reaches, the river Bug is flowing into the Zegrzynskie Lake, a large reservoir that was built as the main source of drinking water for Warsaw.
The main tributaries of the river Bug are:
In Belarus – Kopalovka, Pulva, Lesnaya Pravaya, Lesnaya, Muhavets, Ryta, Maloryta
In Poland – Solokija, Huczwa, Uherka, Krzna, Kamianka, Nurzec, Brok, Liwiec
In Ukraine – Dumni, Gapa, Luga, Poltva, Rata, Solokiia, Studianka