Онежское озеро: второе по величине озеро Европы и его особенности

Freshwater lake in Russia, second largest in Europe

Lake Onega (/ou//'//n//E//g//@/; also known as Onego; Оне́жское о́зеро, ; ; Livvi: Oniegujärvi; ) is a lake in northwestern Russia, on the territory of the Republic of Karelia, Leningrad Oblast and Vologda Oblast. It belongs to the basin of the Baltic Sea, and is the second largest lake in Europe after Lake Ladoga, slightly smaller than Lebanon. The lake is fed by about 50 rivers and is drained by the Svir. There are about 1,650 islands on the lake. They include Kizhi, which hosts a historical complex of 89 Orthodox churches and other wooden structures of the 15th–20th centuries. The complex includes a UNESCO World Heritage Site, Kizhi Pogost. The eastern shores of the lake contain about 1,200 petroglyphs (rock engravings) dated to the 4th–2nd millennia BC, which have also been inscribed as a UNESCO World Heritage Site. The major cities on the lake are Petrozavodsk, Kondopoga and Medvezhyegorsk.

The lake is of glacial tectonic origin and is a small remnant of a larger body of water which existed in this area during an Ice Age. In geologic terms, the lake is rather young, formed – like almost all lakes in northern Europe – through the carving activity of the inland ice sheets in the latter part of the last ice age, about 12,000 years ago: In the Paleozoic Era (400–300 million years ago) the entire territory of the modern basin of the lake was covered with a shelf sea lying near the ancient, near equatoric Baltic continent. Sediments at that time – sandstone, sand, clay and limestone – form a layer covering the Baltic Shield which consists of granite, gneiss and greenstone. The retreat of the Ice Age glaciers formed the Littorina Sea. Its level was first higher than at present, but it gradually lowered, thereby decreasing the sea area and forming several lakes in the Baltic region.

The lake area used to be clean but pollution is gradually increasing, especially in the northwestern and northern parts which contain the industrial facilities of Petrozavodsk, Kondopoga and Medvezhyegorsk. About 80% of the population and more than 90% of industry of the basin are concentrated in these areas. The pollution from these three cities amount to about of sewage and drainage water and of emissions per year. Human activity results in about of drain water per year, of which 46% are industrial and household water, 25% is stormwater runoff and 16% is melioration related drainage. This drainage contains of phosphorus and of nitrogen; respectively of these elements are removed through the River Svir whereas the rest accumulates in the lake. Ships and motor boats (about 8,000 units) bring oil pollution at the level of about per navigation year, as well as phenols , lead and oxides of sulfur, nitrogen, and carbon.

The largest city on the lake is Petrozavodsk – the capital of Republic of Karelia (about 270,000 citizens) – founded in 1703 by Peter I to exploit the natural ore deposits. The city contains several remarkable Neoclassical buildings from Catherine II's reign, including the Circular Square and a gymnasium building (built in 1790). The embankment of Lake Onega contains a series of sculptures, many of which were presented as gifts from the twin cities. Kondopoga has been known since 1495 and (before its destruction in 2018) contained the Uspenskaya (Assumption) Church from 1774. This edifice was the tallest wooden church of the Russian North. There are two carillons in the city, with 23 and 18 bells, also there is an indoor ice sports arena accommodating 1,850 spectators and a Palace of Arts with an organ. The town of Medvezhyegorsk was founded in 1916 and from 1931 became the construction base of the White Sea – Baltic Canal. Between 1703–1710 and 1766–1769 a factory was operating on the site of the city. During the World War II this area was occupied by the Finnish forces and was a place of busy military activities.

The main attraction of the lake is the island of Kizhi in the northern part of the lake, which is a State Historical, Architectural and Ethnographic Preservation Area. There are 89 wooden architectural monuments of the 15th to 20th centuries on the island. The most remarkable of those is Kizhi Pogost of the early 18th century which consists of a summer church with 22 domes, a winter church with nine domes, and a belfry. The pogost was included in the list of UNESCO World Heritage sites in 1990. In the summer, there are daily boat connections to the island from Petrozavodsk.

Another attraction of the lake are the Onega petroglyphs (rock engravings). They are located on the eastern coast of the lake and date back to between the 4th and 2nd millennia BC. There are about 1,200 petroglyphs scattered over the area including several capes, such as Besov Nos (see map above). The engravings are deep and depict animals, people, boats and geometrical shapes of circular and crescent shapes. In 2021, the petroglyphs were inscribed on the UNESCO World Heritage List for its significant artistic qualities that testify the creativity of the Stone Age.

Many other historical monuments are scattered around the lake. They include the Dormition Monastery (ru) on the cape Muromsky, on the eastern shore of the lake. The monastery was founded in 1350, closed in 1918 and revived in 1991.