The Piva is a river in Montenegro and Bosnia and Herzegovina, shorter headwater of the Drina river, which it forms with the Tara river on the border with Bosnia and Herzegovina. The Piva springs from the Sinjac spring on Golija mountain, near the Piva Monastery (also called Vrelo Pive; Well of Piva). Before the artificial Lake Piva (Pivsko Jezero) was formed, the water from the well rushed into the river Komarnica thus creating the Piva river for the next 34 km.
However, Komarnica is part of a 86 km long river system (Tušina–Bukovica–Bijela–Komarnica), so measured from the source of the Tušina river, the Piva, nicknamed ‘the river with five names’, is 120 km long. The Tušina originates from the mountain Sinjajevina in the Uskoci region of central Montenegro, just few kilometers away from the source of another important Montenegrin river, Morača. The river flows to the west, between the Sinjajevina and Lola mountains, next to the villages of Krnja Jela, Bare, Boan and Tušina.
It receives from the north the Bukovica river, and continues further under this name. After the river passes the regional center of Šavnik and the villages of Gradac and Pridvorica in the region of Drobnjaci, the stream receives from the north the Komarnica and takes its name. The Komarnica continues between the mountains of Vojnik and Treskavac, in an almost uninhabited area (village of Duži) and enters the high Piva Pleateau, where it turns north (almost all of the Komarnica’s course is flooded by the reservoir of the Lake Piva), receives from the right outflow of the Piva well and enters the deep Piva canyon.
The canyon is cut between the mountains of Bioč, Volujak, Maglić and Pivska planina, its 33 km long, deep up to 1.200 m and river generates immense power used for the power station of Mratinje (342 MW) which dammed the canyon in 1975. The dam is 220 m high, one of the highest in Europe and creates Lake Piva, third largest in Serbia and Montenegro (12,5 km², altitude 675 m, 188 m deep), which flooded the old location of the monastery of Piva from the 16th century, so the monastery was moved to the new one.
The Vrbnica river flows from the left into the lake. After the dam, the Piva continues straight to the north, meets the Tara at Šćepan Polje on the border with Bosnia and Herzegovina and creates the Drina. The Piva belongs to the Black Sea drainage basin with its own drainage area of 1.270 km² and is not navigable. After several attempts, finally a group of alpinists from Niksic managed to do pass through the canyon. Today we pass the canyon in organized guided groups with all necessary, modern equipment (for alpinists and divers ) and communication and navigation means. Canyon is about 3.8 km long and it takes almost the entire day for passing.
Pivska površ, is a high limestone plateau in the drainage area of Piva, between the mountains of Durmitor, Maglić, Lebršnik, Golija and Vojnik. The plateau is 55 km long, 30 km wide with an average altitude of 1.200 m, the highest 2.159 m. The flow of Komarnica-Piva divides it in two regions: western one, Pivska Župa and eastern one, Pivska planina . Area is characterized by many limestone features, like cavities (called vrtača) deep pits and excavations, and extremely sparsely populated (some 20 smaller settlements in Pivska Župa and 15 in Pivska planina). Stock breeding is developed though, especially sheep.
The Mratinje Dam is a concrete arch dam in the canyon of the Piva River in Montenegro. The dam was completed in 1975 with designs by Energoprojekt. Its construction resulted in the flooding of the Piva canyon and the creation of Lake Piva, which, with its 12.5 km², is the second largest lake in Montenegro. The dam is 220 metres (720 ft) high, one of the highest in Europe. The dam is 268 metres (879 ft) long and 4.5 metres (15 ft) thick at the crest, while it is 30 metres (98 ft) long and 36 metres (118 ft) thick at the base. The foundations go as deep as 38 metres (125 ft) into the ground. 820,000 cubic metres (1,070,000 cu yd) of concrete and 5,000 tonnes of steel were built into the dam. The hydroelectric power station at Mratinje is capable of producing 860 gigawatt-hours per annum. It has three turbines and generators, each with a generation capacity of 120 MW. The location of the 16th century Piva Monastery was flooded by the lake, so while the dam was built, the monastery was broken into pieces and moved to a higher ground, 3.5 km away. It was reconstructed in the original way.