Determination of Some Physico-Chemical Parameters of the Nairobi River, Kenya

This paper discusses the results of a study carried out in 2003 on the water quality of Nairobi River on the basis of pollution parameters and water quality index. The study aimed at establishing whether the water meets the surface water quality criteria for water supply. The area of study in Nairobi River was within its entry and exit of Nairobi province. It was observed that human activities along the river with visible encroachment to the banks, contribute to the heavy level of pollution of the river. This is the section that industrial discharges and municipal sewerage are discharged into the river. The study was carried out through field surveys and laboratory tests on samples taken from the river. The results obtained from laboratory tests were analysed and compared to the established surface water quality criteria by A.S.C.E, W.H.O, Natural watercourses Standards of Kenya and classification of rivers by Royal Commission on Sewage Disposal. Human activities along the river course have severely impacted on the River water quality. The study area had average pH of 7.04; the average turbidity was 41.5N.T.U, the average suspended solids in the section was 116.43 mg/l, the average dissolved oxygen was 4.32mg/l. the average BOD was 182.5mg/l. The average COD for the reach studied was 49.5mg/l. The river was therefore classified as bad according to Klein 1966. The study concluded that the Nairobi River within Nairobi province was badly polluted as indicated by the water quality index analysis. The WQI gives a value of 49.27, fall between the numerical ranges of the classification of bad (26-50).