, Imatra, Finland Around 5,000 BP the waters of the
Saimaa Lake penetrated
Salpausselkä, forming the river emptying into Lake Ladoga in its northwestern corner and raising the level of the latter by . Lake Ladoga
transgressed, flooding lowland lakes and the Vuoksi, and connected with the
Baltic Sea at
Heinjoki, to the east of present-day
Vyborg. Ladoga's level gradually sank and the River Neva, originating around 3100–2400 BP, drained its waters into the Gulf of Finland; but the Vuoksi still had a significant direct outflow connection to the
Bay of Vyborg, possibly as late as in the 16th or 17th century AD. The connection disappeared due to ongoing land uplift. In 1818, a canal was dug to drain spring flood waters from
Lake Suvanto (now Lake Sukhodolskoye, a long narrow lake in the eastern part of the
Karelian Isthmus) into Lake Ladoga; the canal unexpectedly eroded and turned into
Taipaleenjoki (now Burnaya River). The Taipaleenjoki started draining Suvanto and decreased its level by . Originally Lake Suvanto flowed into the Vuoksi through a waterway at
Kiviniemi (now Losevo), but as a result of the change, the waterway dried out. In 1857 a channel was dug there, but the stream reversed direction, creating
rapids and rendering navigation at Kiviniemi impossible. Since 1857 Suvanto and Taipaleenjoki have constituted the southern branch of the Vuoksi, which has decreased the level of the original northern branch emptying into Ladoga near
Kexholm (now Priozersk) by and has become the main stream. ==References==