It flows west past Kiremba, then southwest through marshes to the Akanyaru River.

[3] The surroundings of Buyongwe River are a mosaic of farmland and natural vegetation.

[7] The area of the present Buyongwe marshes were dominated by Syzygium, Phoenix and Macaranga trees from 2700 and 1200 years ago.

Then the trees began to disappear, possibly due to exploitation by Iron Age people, and there was an increase in aquatic plants that indicates a rising water table.

[8] Today, the Buyongwe marshes are surrounded by densely populated basins, and used to grow two crops of rice per year.