Changes in water quality of the rivers discharging into Lake Tanganyika in Bujumbura, Burundi

Sources of pollution at the northern end of Lake Tanganyika are concentrated around Bujumbura, Burundi. This article studied the water quality characteristics of seven inflowing rivers emptying into Lake Tanganyika. Chemical analyses were carried out during rainy and dry seasons. The nutrients and suspended solids at some sites were above the critical level for healthy river water. Contamination was concentrated mainly around urban areas which have been newly developed to accommodate the rapidly growing population in the country. Compared to previous studies, the concentrations of nutrients in the river water were relatively high, indicating increasing pollution in Bujumbura's rivers. The mean values of physico-chemical parameters, with the exception of suspended solids, were found to be higher in the dry season than in the rainy season. This result is consistent with previous studies. Principal components analysis and factor analysis were employed for numerical analyses, and proven to be useful to assess the source of pollution in specific river sites, where monitoring data is missing. Routine monitoring of basic physical and chemical indicators of water quality is recommended for all urban lakes and rivers in order to protect both the aquatic ecosystem and health of the local residents living near the lake.