Pollution and Vulnerability of Water Supply Aquifers in Mombasa Kenya: Interim Progress Report.

Abstract

The available information on groundwater quality in the Mombasa District suggests that the aquifer is experiencing contamination primarily due to the use of on-site sewage disposal systems, in particular pit latrines and septic tank / soak pit systems. The degree and extent of aquifer contamination in the island is variable, with sewered areas showing least groundwater pollution. It is apparent that areas of Kisauni are experiencing serious groundwater contamination attributed to sewage disposal practices. The situation in Kisauni is expected to worsen with the increasing population pressure, inadequate waste management practices and over-dependence on groundwater for potable needs. The situation in Likoni is expected to assume a similar trend. While the information accessed clearly demonstrates a credible threat to the groundwater quality, it is by no means conclusive. There is need to address the data and information gaps with due attention on detail in order to develop a clearer picture of the situation. This entails putting in place a systematic monitoring programme, focussing on, among other factors, the following: (1) Physico-chemical indicators of water quality, in particular salinity, conductivity, pH, ammonia, nitrates, phosphates and selected heavy metals; (2) Microbial indicators of groundwater contamination, namely total coliform, faecal coliform and E. coli; (3) Piezometric data and related geohydrologic parameters to extend and refine the intrinsic aquifer vulnerability model; (4) Saline water intrusion as a result of over-abstraction of groundwater; (5) Land use to identify sources of contamination of groundwater; (6) Elucidate the influence of seasonal weather activities, especially seasonal rains, on aquifer recharge and groundwater quality.