ONEGA (On'e-gah), the largest lake in Europe next to Ladoga, area, 3,764 sq.m. and coast line 870 m. in length. It lies mostly in the Karelian A.S.S.R., though its southern portion is in the province of Leningrad. The lake basin extends north-west and south-east, the direction characteristic of the lakes of Fin land and the line of glacier-scoring observed in that region. The southern coast is comparatively regular and has few islands, but the north is broken into inlets, the largest being Povyenets bay, and is crowded with islands (e.g., Klimetsk) and submerged rocks.
The north-western shore between Petrozavodsk and the mouth of the river Lumbosha consists of dark clay slates, generally arranged in horizontal strata and broken by protruding, parallel ridges of diorite, which extend far into the lake. The eastern shore, as far as the mouth of the Andoma, is for the most part alluvial, with outcroppings of red granite and in one place (the mouth of the Pyalma) diorite and dolomite. To the south-east are sedimentary Devonian rocks, and the general level of the coast is broken by Mt. Andoma and Cape Petropavlovskiy (160 ft. above the lake) ; to the south-west a quartz sandstone (used as a building and monu mental stone in Leningrad) forms a fairly bold rim. Lake Onega lies 125 ft. above the sea. The greatest depths, 318 to 408 ft., occur at the entrance to the double bay of Lizhemsk and Unitsk. On the continuation of this line the depth exceeds 24o ft. in several places. In the middle of the lake the depth is 120 to 282 ft., and less than 120 ft. in the south. The lake is 145 m. long, with an average breadth of 5o m. The most important affluents, the Vodka, the Andoma and the Vytegra, come from the east. The Kumsa, a northern tributary, is sometimes represented as if it connected the lake with Lake Seg, but at the present time the latter drains to the White sea. The Onega canal (45 m. long)
was constructed in 1818-51 along the southern shore in order to connect the Svir (and hence Lake Ladoga and the Baltic) with the Vytegra, which connects with the Volga. In 1928 an electric station was constructed on the Svir river. Lake Onega remains free from ice for 209 days in the year (middle of May to second week of December). The water is at its lowest level in the begin ning of March ; by June it has risen 2 ft. A considerable popula tion is scattered along the shores of the lake, mainly occupied in the timber trade, fisheries and mining industries. The opening of the Murmansk railway along the western shore in 1917 is de veloping settlement. Salmon, palya (a kind of trout), burbot, pike, pike perch and perch are among the fish caught in the lake.
The River Onega rises in Lake Vozhe, and is navigable for boats and rafts to Kargopol on Lake Lacha to the Gulf of Onega, an inlet of the White sea. It flows through the provinces of Vol ogda and Archangel and has no connection with Lake Onega. At the mouth of this river (on the right bank) in 55' 55' E., in the province of Archangel, stands the town and port of Onega. Pop. (1926) 5,254. It dates from settlements made by the people of Novgorod in the 15th century, known in history as Ustenskaya or Ustyanskaya. It has a saw-milling industry, and has summer steamer routes to Soroka, Kern and Archangel, but the season is short owing to the persistence of land floes and loose pack. Telegraphic communication is by the Archangel rail way.