The Nyawarungu River meanders southward through the valley, flooding it to create a zone of permanent swamps and lakes.

[1] The lake is fed by a number of rivers and minor streams originating on ridges to the north, east and south, which deliver most water during the rainy seasons.

Other animals include water turtles, crocodiles, monitors, snakes and otters.

[4] In the 15th century the region around the lake was settled by the Hondogo lineage of Tutsi people, pastoralists who had formed an independent state.

They gradually acquired power in most of the region of modern Rwanda, while intermarrying with the Hutu and becoming culturally assimilated by them.