In only four hours in the night of 6/7 June 1796, Ragundasjön drained completely, triggering a 25 meters flood wave moving down the river towards forests, islands, sawmills, residential buildings, boat houses, utility buildings, barns, fields and meadows, causing much destruction and establishing the much deepened and scoured-out course of the canal and the Lokängen valley as part of the river's new course, and carrying a huge load of debris, probably thus restoring its prehistoric course as before the Ice Age.