Nairobi River has several tributaries, including (in descending order from north to south):
Motoine River flows to the Nairobi Dam, an artificial lake meant to provide drinkable water for residents of Nairobi. Further onwards the stream continues as Ngong River.
Nairobi's rivers suffer from contaminations by agriculture, slums and industrial areas . Some river banks are also infamous for insecurity. These rivers divide the city due to lack of proper crossings.
During rainy seasons the discharge tends to multiply, causing floods on low-lying riverbanks.
There is a second river called Nairobi in Kenya. It starts on Mount Kenya and is a tributary of the Sagana and then the Tana, the longest river in Kenya.