Lake Lacha Lake Lacha Lake Lacha () is a freshwater lake, located in the south of Kargopolsky District of Arkhangelsk Oblast in Russia, south of the town of Kargopol. It is the largest lake in Arkhangelsk Oblast, with a surface area of and a basin area of . Lake Lacha is the source of the Onega River, one of the major waterways of the White Sea basin. The etymological origin of the name is unclear. The river basin of Lake Lacha includes the southern and western parts of Kargopolsky District of Arkhangelsk Oblast, as well as north-west of Vologda Oblast. In particular,
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