Klang River is a river which flows through Kuala Lumpur and Selangor in Malaysia and eventually flows into the Straits of Malacca. It is approximately 120 km in length and drains a basin of about 1288 square kilometres. Klang River has 11 major tributaries. Given the fact that the river flows through Klang Valley which is a heavily populated area of more than four million people, it is considerably polluted. Heavy development has narrowed certain stretches of the river until it resembles a large storm drain. This contributes to flash floods in Kuala Lumpur, especially after heavy rain. Klang River was used to be called Sungai Seleh.