Lake Onega (redirected from Onego Lake)

Onega, Lake 

a lake in the northwestern part of the European USSR, in the Karelian ASSR and the Leningrad and Vologda oblasts of the RSFSR. It covers an area of 9,700 sq km, excluding islands, and has an average depth of 30 m and a maximum depth of 120 m. When the level is average, the water volume is 292 cu km. The lake lies in a tectonic basin altered by a glacier in the Anthropogenic period. It extends for almost 250 km from northwest to southeast and has a maximum width of 91.6 km. The high rocky coast in the north and northwest is composed of granite and gneiss. Here the coastline is greatly indented, with narrow bays cutting deeply into the land. Among the largest bays are Petrozavodsk, Kondopoga, and Povenets. In the north and southeast the shore is mainly low, straight, and composed of sand or sometimes clay. It is frequently swamped and flooded during high water. In the north and northwest the topography of the bottom is rugged; deep depressions descending as much as 115m alternate with small areas of higher ground. In the south the floor is smooth with depths of up to 50 m.

Lake Onega has 1,369 islands totaling 250 sq km, of which the largest are the Bol’shoi Klimetskii and Bol’shoi Lelikovskii. Of the 58 rivers draining into Lake Onega, the main ones are the Shuia, Suna, Vodla, and Vyterga; the Svir’ River flows out of the lake. Drainage is regulated by the Verkhniaia-Svir’ Hydroelectric Power Plant. In the lake’s water balance, rivers account for up to 74 percent of the water intake (15.6 cu km per year) and precipitation for 25 percent; 84 percent of the lake’s water loss occurs through drainage via the Svir’ River (an average of 17.6 cu km annually) and 16 percent through evaporation. The highest water levels occur between June and August, and the lowest, in March and April. The water level may vary by as much as 190 cm, although the average fluctuation is about 50 cm. Wind action can cause variations of up to 60–65 cm in the water level of the northern and southern ends of the lake. Seiches also occur. There are differences in temperature between the deep central part and the shallow coastal areas. The highest surface temperature in August is 20°–24°C in the center and 24°–27°C in the bays. The temperature of the bottom water ranges from 2°–2.5°C in winter to 4°–6°C in summer. The center of the lake freezes in mid-January, and the coastal waters and bays, in late November or December. The breakup of ice occurs in late April at the mouths of the rivers flowing into the lake and in May in the center. The water transparency, 8–9 m over most of the lake, ranges from 1–2 to 3–4 m near the shore. The water is fresh, with a mineral content of 35 mg per liter.

Lake Onega has 47 species of fish, of which 17 are important for the fishing industry. Commercial species include cisco, smelt, pikeperch, burbot, bream, perch, pike, whitefish, and salmon. The Baltic-White Sea Canal connects the lake with basins of the Baltic and White seas, and the V. I. Lenin Volga-Baltic Waterway joins it with the Volga basin. The lake is extremely important for both domestic shipping and the transport of cargo to Finland, Sweden, the German Democratic Republic, Denmark, and other countries. The lake’s island of Kizhi is a state open-air museum of wood architecture. The main cities along the coast are Petrozavodsk, Kondopoga, and Medvezh’egorsk.

REFERENCES

Ozera Karelii. Spravochnik. Petrozavodsk, 1959.
Grigor’ev, S. V. Vnulrennie vody Karelii i ikh khoziaistvennoe ispol’zovanie. Petrozavodsk, 1961.
Bogoslovskii, V., and Iu. Georgievskii. Onego. Leningrad, 1969.
Sekachev, A. A. “Vodnyi balans Onezhskogo ozera.” Sbornik rabot Leningradskoi i Petrozavodskoi gidrometeorologicheskikh observatorii, issue 6. Leningrad, 1970.
Teplovoi rezhim Onezhskogo ozera. 1973.

K. G. TIKHOTSKII