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,
Vytegorsky District Vytegra. Population: 31,757 (2002 Census); The population of Vytegra accounts for 38.6% of the district's total population. The northwestern border of the district is the shore of Lake Onega, and the area of the district is divided between several drainage basins. The western and the central parts belong to the basins of the rivers flowing into Lake Onega, most notably the Vytegra, the Vodla, the Andoma, and the Megra. Lake Onega belongs to the basin of the Neva River. From the east, the Andoma Hills separate the basin of Lake Onega from the basins of the Kovzha and the Kema