A study of the water quality of the Mhlathuze River, KwaZulu-Natal (RSA): microbial and physico-chemical factors

Abstract

The microbial quality (total and faecal coliform counts) and some physico-chemical parameters of the Mhlathuze River water source were monitored during March 2001 to November 2002 and compared to the previous study conducted during 1998-1999. The results showed that most of the physical and chemical values obtained were within the recommended limits specified in the South African Water Quality Guidelines. High concentrations of metal were detected in water samples from Felixton and the Richards Bay estuary. Water samples from the Mhlathuze Pumping Station and Felixton, which contained higher concentrations of total nitrogen and phosphate, possessed higher faecal coliform contamination than other sites. The total coliform counts of the Mhlathuze River in this study period were noted to be significantly higher than those in the 1998 to 1999 period. As observed in the previous study, Felixton continues to be the site with major faecal contamination. The resuscitation results indicated that the level of faecal contamination in the Mhlathuze catchment was higher than that measured using conventional methods. Therefore the real impact of this \"viable but non-culturable\" state of micro-organisms in this water system requires urgent attention. Larger fluctuations in the trend of total and faecal coliform counts were observed in 2001. This phenomenon coincided with the major construction of the Mhlathuze pumping station. High water surface temperatures and rainfall figures might have also contributed to this observation. Evidence from our results strongly suggests that the use of faecal coliform bacteria as indicators should be expanded and more research is indicated to identify the impact of the \"viable but non-culturable\" (VBNC) state of pathogens in this environment. Water SA Vol.30(1): 17-22