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.
CHAPTER ONE
INTRODUCTION
Background information
Mara basin is a trans-boundary water catchment tower comprising of various small rivers, streams and their tributaries that merge together to form the great River Mara. The River Mara is shared between Kenya and Tanzania and drains its water into Lake Victoria. It flows through open savannah grasslands and eventually into Maasai Mara Game Reserve and Serengeti National Park, an important tourist destination in Africa famous for the seven big animals and the spectacular wonders of the annual wildebeest migration. The main tributaries of Mara River are Amala and Nyangores Rivers which are both under serious threat as a result of change in land use to accommodate various purposes like human settlement and urbanization among others in the catchment. This has eventually led to drastic reduction in forest cover which has hampered the recharge of the river with faster surface runoff leading to the degradation of the water quality and quantity (Mati and Mutunga, 2005).
Human development which entails land clearing, urbanization and poor waste disposal measures along the tributaries of most rivers as in the case of the Mara River has significantly degraded the biological and chemical quality of its water. The consequence of this is to trigger the occurrence of point and non-point sources of pollution which have been found in other rivers too (Yillia et al., 2009). Several other studies have also shown that increased intensity of human activities such as arable farming, livestock keeping, mining, industrial activities and urban settlement adjacent to river water bodies as in the case of Mara basin often impacting negatively on the quality and quantity of water (Mokaya et al., 2004). River Nyangores originates from Mau forest and flows through an area with intensive anthropogenic activities (Mati and Mutunga, 2005) (Plate 1). Human activities such as settlement, urbanization and poor farming methods have not only been perceived to be the major cause of degradation to the quality of water in this river, but also to both River Mara and Lake Victoria where water from the tributary is emptied (Dadwell, 1993). Faecal pollution to water sources is a serious threat to the quality of water with a negative impact on the integrity of aquatic ecosystems and therefore is a risk to the health of the community consuming water from such sources. It is believed that 80% of all diseases in the world are caused by inadequate sanitation, polluted water or unavailability of water (WHO, 2002). Both direct contact and consumption of water contaminated with faeces of ill individuals can lead to human illness and even death (United State Environmental Protection agency (USEPA), 1995).
To test for the microbial quality of any water source, faecal contamination indicator organisms are preferred as the approach is fast and cheap (APHA, 2005). While a variety of pathogenic indicators have been proposed, the mostly commonly used estimator of faecal pathogenic bacteria presence is faecal coliforms and faecal streptococci abundance (Dadwel, 1993, Ford and Colwell, 1996). Traditionally, indicator micro-organisms have been used to suggest the possibility of presence of pathogens (Berg and Metcalf 1978). A direct epidemiological approach could be used as an alternative or adjunct to the use of index micro-organisms. However epidemiologic methods are generally too insensitive and miss the majority of waterborne disease transmissions (Frost et al. 1996). Other useful indicators include intestinal enterococci and Clostridium perfrigens. Organic matter loading from catchment activities results in vigorous consumption of oxygen attributable to large oxygen requirement by heterotrophic microbes in oxidative degradation processes. High Biological Oxygen Demand (BOD) is experienced in such systems and oxygen deficit is greatly increased often leading to destruction of other aquatic organisms. Thus BOD5 is used as a measure of oxygen consumption and aerobic heterotrophic activities (Rheinheimer, 1991). Inorganic nutrients (PO4 and NO2) from agricultural activities also affect microbial flora of streams (Yuan et al., 2001).
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Item Type: Kenyan Topic | Size: 63 pages | Chapters: 1-5
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