An assessment of the health-related microbiological water quality of the Blesbok Spruit

M.Tech.South Africa is a water scarce country. The characteristic water pollution problems associated with both developing and developed economies are evident. Indicator organisms have been enumerated from samples collected from the Blesbok Spruit (Gauteng Province) over one year. Standard membrane filtration techniques were used followed by cultivation of E. coli and enterococcus on selective agars. Rainfall data was collected to enable a determination of differences, between “wet” and “dry” sampling runs. Descriptive statistics applied to the data include the calculation of the geometric mean for each sampling run and the geometric mean per sampling site in both wet and dry conditions. The Mann- Whitney Rank Sum Test and Kruskal-Wallis One way Analysis of Variance (ANOVA) were used to compare data sets. The capacity of the Blesbok Spruit, containing wetland areas, to assimilate the microbiological load was more effective than that of the Renoster Spruit (Free State Province) which does not contain distinctive wetland areas. The risk of infection has been determined by comparing the levels of E. coli and enterococcus to a set of site-specific guidelines. The water is not suitable for drinking or domestic purposes and full contact recreation will pose a risk of infection to users. The lower Blesbok Spruit has the poorest water quality and this water is unsuitable for livestock watering being only suitable for the irrigation of crops. The effects of diffuse pollution on the health related microbiological water quality need to be considered in the management of this sub-catchment