Evaluation of water quality and identification of pollution hotspots on Kabaka's lake.
MBONYE, Derrick Bakunzi
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Rural-urban migration has caused a rapid increase in the population of Kampala city. The rate of population growth has exceeded the capacity of Kampala City Council Authority to plan for the city (UN-HABITAT, 2007). As a result, there has been development of unplanned human settlements that are associated with poor sanitary facilities and unimproved solid waste management which contribute to the pollution of surface and groundwater. This study looked assessed the extent of pollution on Kabaka’s Lake located in a suburban region in Kampala. The lake is located in Ndeeba, a few kilometres from the city center and is surrounded by unplanned settlements and a number of institutions. Because of the gradual pollution that has taken place on the lake, the water looks green to an observer. In addition, solid waste can be seen on the shores and in the water, and the water levels are continuously dropping, and yet, the lake is of great cultural significance to Buganda Kingdom, a potential tourism center in Uganda, a potential urban recreational center and a habitat for aquatic flora and fauna. The aim of the study was to identify sources of pollution on the lake, estimate pollution loads, compile a pollution inventory, assess the spatial and temporal variation of water quality and to recommend preventive and control measures according to the findings. This was done by delineation of the catchment, reconnaissance surveys in the catchment, sanitary surveys, water quality tests on the lake and at the inlets and a bathymetry study. The major pollutants identified on the lake were faecal coliforms, BOD, COD, TP, TN and suspended solids. Suspended solids are mainly from the runoff from the catchment of the lake which has bare land, unpaved roads and clogged drainage systems. The lake is also in a low-lying region which makes it a collection point for runoff from the catchment. Faecal coliforms, BOD, COD, Nitrogen and Phosphorous are mainly from the waste water and leachate from settlements and commercial land use. The findings from the bathymetry study were compared to a study done in 2018 and it was found that the lake suffers from sedimentation and the sediment yield was determined. To reverse the effect of sediment accumulation in the lake over the years, dredging has been recommended in a 2018 study. From the sediment yield, a new dredging volume has been recommended. Use of buffer strips at the shores of the lake, improvement of sanitary facilities and solid waste management systems, sensitization of the communities around the lake on the effects of human activities on water quality and the subsequent consequences of these effects on human life have been recommended.