An assessment of water quality changes within the Athi and Nairobi river basins during the last decade

Abstract

This paper examines the changes in water quality that have occurred within the Athi and Nairobi river basins in the last decade. The main focus is to examine the trends in water quality degradation, pollutant sources and pollution levels since the early 1990s to year 2000 and beyond. It draws its major findings from two research projects done within the basins over the same period. The two research projects revealed increasing trends in water quality degradation due to changes in land-use systems. Industrial, population (rural-urban migration) growth and agricultural activities were found to contribute significant amounts of water pollutants, thus degrading the water quality status in the two river basins investigated. This is of major concern to national water policy makers and environmentalists, as well as the Kenyan government in general. This paper reviews some of the possible mitigation strategies as means of mitigating against future water quality degradation trends and to abate the problem in good time. The use of riverine vegetation (macrophytes) and stormwater in the basins are recommended for reducing water quality degradation status in the two basins and other similar catchment areas in the country. Plant species Commelina benglensius, Sphaeranthus napirae and Xanthium pungens proved useful in adsorbing some of the pollutants, and especially heavy metals.