Impact of anthropogenic activities on bacteriological water quality of Nyangores River, Mara basin-Kenya

Abstract

The Mara River basin is the lifeline to Maasai Mara Game reserve in Kenya and the Serengeti National park in Tanzania. Its major perennial tributaries are Nyangores and Amala both originating from Mau Escarpment. Unprecedented evidence on change of land use for development purposes in the upper catchment has affected the water quantity, quantity and the environmental sanitation in general. In addition, the municipal town of Bomet situated close to Nyangores River lack adequate sanitation facilities, these might have greatly degraded the water quality through discharge of raw faecal matter into the river. Another notable area of concern is the nearby Tenwek Mission Hospital whose waste water lagoons are located close to the bank of the same river with their waste effluents being directly disposed to this river. Such waste disposal methods create point and non-point sources of pollution with different degrees of pollution. This study investigated the effect of human settlement and development on the microbial water quality of Nyangores River at various points along its river channel based on the intensities of human settlement and development. To establish the microbiological water quality, the study involved the use of Membrane Filtration Technique (MFT) to determine the densities of total coliforms, Escherichia coli, intestinal enterococci, Clostridium perfringens and Salmonella spp. followed by plating on selective differential media for the bacteria being sought. Pollution with easily biodegradable organic wastes was detected by Heterotrophic Plate Count (HPC) procedures and BOD5 determination. Physico-chemical parameters; temperature, dissolved oxygen (DO), conductivity, turbidity, total dissolved solids and pH of the water at the sampling sites were also measured at the time of sampling using appropriate measuring meters. The collected data was analysed using Statistical Package for Social Sciences (SPSS) version 17 software with a confidence level of 95%. The results indicated spatial and temporal variation in the densities of faecal contamination indicators P<0.05. Indicators of contamination with easily degradable organic matter (BOD and HPC) also showed significant spatial and temporal variations, P<0.05. All the sites studied except site 1 at Kiptagich were found to be contaminated with Salmonella spp. Physicochemical parameters studied also showed significant spatial variation except DO, P<0.05. In conclusion, the presence of anthropogenic activities along Nyangores River have impacted negatively on quality of its water and therefore appropriate corrective mechanisms are necessary to help improve or restore its water quality so as to uphold its ecological integrity and be safe for domestic use.