 The Nyabarongo River, part of the upper headwaters of the Nile, forms the western and southern borders of the administrative city of Kigali, although this river lies somewhat outside the built-up urban area.The largest river running through the city is the Nyabugogo River, which flows south from Lake Muhazi before flowing west between Mount Kigali and Mount Jali, and draining into the Nyabarongo.The Nyabugogo is fed by various smaller streams throughout the city, and its drainage basin contains most of Kigali's territory, other than areas in the south which outflow directly to the Nyabarongo.