Assessment of the sources and types of pollutants in Nairobi River

Abstract

Studies on the various tributaries of Nairobi River and basin conducted in the 1990s showed evidence of high levels of chemical and organic pollution. Ngong, Mathare and Nairobi Rivers pass through high human settlement areas. As a result, these rivers have been heavily polluted resulting to loss of good water qualities and biodiversity. Raw sewage from informal settlements and discharge from industries are main polluters of Nairobi River. Other key sources are incidences of burst/blocked sewers and solid waste discarded into the river and excessive levels of heavy metals. These are a threat to humans utilising the water for domestic and agricultural purposes. They lead to increased COD leading to anoxic conditions in water and sediments. Continued water pollution has led to: Health problems, stress on immediate aquatic ecosystems as well as downstream, reduction of the economic value and its natural beauty. The study’s main objective is to determine the status of Nairobi River downstream, and establish a baseline for monitoring water quality improvement efforts.