The Upper Nyabarongo catchment is part of the Nile basin and runs from south to north in the western part of Rwanda. The catchment is known as the water tower of Rwanda and boosts a significant number of tributaries, of which the most important are (from south to north) the Mwogo River (81.1 km), Rukarara River (47.4 km, springing from the Rubyiro and the Nyarubugoyi rivers), Mbirurume River (51.6 km), Mashiga River (12.2 km), Kiryango River (10.4 km), Munzanga River (24.4 km), Miguramo River (15.0 km) and the Satinsyi River (59.7 km).
The major economic activities in Upper Nyabarongo are agriculture and livestock, hydropower, trade and mining (especially in the districts of Muhanga, Ngororero, Rutsiro, Ruhango, Nyamagabe, Huye and Nyanza), and small agro-industries (maize, rice, cassava, banana, fruits, soybean, milk and honey). The catchment is also home to a number of coffee washing stations and tea factories.
The catchment is characterised by soil erosion from poor agricultural practices, illegal mining activities and deforestation, causing heavy siltation in the Nyabarongo River and tributaries.