Onega River Onega River The Onega (; ) is a river in Kargopolsky, Plesetsky, and Onezhsky Districts of Arkhangelsk Oblast in Russia. The Onega connects Lake Lacha with the Onega Bay in the White Sea southwest of Arkhangelsk, flowing in the northern direction. The discharge at the source is and at the mouth is . The river is long, and the area of its basin . Its main tributaries are the Voloshka (right), the Kena (left), the Mosha (right), the Kodina (right), and the Kozha (left). The major tributary of the Lake Lacha is the Svid. The name of the river is
Lake Onega in its center. Thawing starts in April in the tributaries and reaches the lake in May. Water in the deep parts is clear, with the visibility up to . In the bays, the visibility may decrease to about a meter. The water is fresh, with a salinity of 35 mg/L. This is relatively low for a lake and is about times lower than in the other large lake of the area, Lake Ladoga. The maximum surface water temperature is on the open lake and in the bays. The deep waters are much colder, from in winter to in summer. Weather