Effects of lakeshore sanitary activities on water quality: a case study of Lake Victoria, Kenya

Fresh water lakes amongst them Lake Victoria have experienced significant changes in its water quality leading to adverse health effects, loss of biodiversity as well as negative socio-economic impacts. This study sought to investigate the impacts of population increase and specifically the associated human sanitary activities around the shores on water quality with Lake Victoria as a case study. 54 water samples were collected from selected water points (close to point and non-point sources of pollution) in Dunga, Usenge and Port Victoria beaches using grab sampling method and analyzed for physical, chemical and biological contaminants using the APHA standard method. Water quality index at each sampling location was determined and spatial variability in water quality across the beaches mapped using Arc map. Observation checklist and survey guides was used to assess the potential sources of pollution and characterize key lakeshore sanitary activities influencing water quality in the selected beaches. Results showed moderate to poor water quality, particularly along the Nyanza Gulf (Usenge and Dunga) compared to the open lake (Port Victoria). Nutrient concentrations especially of indicator nutrients mainly SRP and ammonium ranged from (14.5-99.7 µg/l) and (8.7-79.4 µg/l) respectively indicating risk of eutrophication. Elevated microbial contamination was recorded in Dunga with total and fecal coliforms averaging at 2322 and 1430 CFU/100ml respectively. Qualitative findings revealed that human sanitary activities greatly influenced contaminant concentration with highest concentration of indicators parameters recorded at points of greater influence. Sampling points at close proximity to point sources of pollution consistently indicated highest levels of total and fecal coliforms of above 1000CFU/100ml. Therefore, human sanitary activities around Lake Victoria shores were found to significantly affect the lake water quality.