Spatial and Temporal Variations in Microbiological Water Quality of the River Wiwi in Kumasi, Ghana

Abstract

Microbial contamination of surface waters in urban areas remains a central problem in Ghanaian inland waters. This research was conducted to assess the microbiological water quality along the longitudinal gradient of the River Wiwi in Ghana to cover five main communities that use and abuse the water for a range of activities. Microbial water quality of the river water was sampled bi-weekly for a 4-month period commencing November 2012 and ending in February 2013 at five sampling locations (Site 1–Site 5). Water samples were examined for total and faecal coliforms, Escherichia coli, Salmonella spp. and faecal enterococci. Mean total and faecal coliform counts ranged from $2.3\times 10^{5}$ to $2.4\times 10^{8}\,100~\mathrm{{ml}}^{-1}\mathrm{{~CFU}}$ and $9.0\times 10^{4}$ to $9.5 \times 10^{6}100~\mathrm{{ml}}^{-1}\,\mathrm{{CFU}}$, respectively. E. coli counts ranged from 0.00 to $9.3{\,\times \,}10^{8}100~\mathrm{{~ml}}^{-1}\,\mathrm{{CFU}}$ during the study period, with faecal enterococci counts ranging from $2.0\times 10^{1}$ to $3.2\times 10^{2}\, 100~\mathrm{{~ml}}^{-1}\,\mathrm{{CFU}}$. The most upstream site (Site 1) consistently recorded the lowest coliform counts over the sampling period. Mean faecal enterococci counts, generally, increased downstream. There were significant differences ($p<0.05$) in mean counts of enterococci between the sampling stations. Relatively higher microbial counts were recorded at during rainy period in November. Significant variations in microbial loads were observed at the different sampling locations, implicating the varied community land-use activities in the catchment. Overall, the microbial count of the River Wiwi exceeded the WHO (2006) standard ($1.0\times 103,100~\mathrm{{~ml}}^{-1}$ CFU) rendering the water unsuitable for domestic use or for irrigation of vegetables for direct consumption.