This study examined the effect of drainage system management practices on plastic pollution levels in Lake Victoria, with a case study of Nakivubo Channel in Kampala District. The research aimed to assess the types of drainage management practices implemented, identify the types of plastic pollution transported through the channel, and determine the challenges affecting effective drainage management. The study adopted a descriptive survey design and involved a sample of 120 respondents, including residents, business operators, and municipal officials, selected using purposive and stratified sampling techniques. Data were collected using questionnaires and interviews and analyzed using descriptive statistics, including frequencies, percentages, means, and standard deviations. The findings revealed that routine cleaning, structural interventions such as channel lining, and debris removal improved water flow but were insufficient to fully control plastic pollution due to improper waste disposal, encroachment, limited institutional capacity, low public awareness, and seasonal rainfall. Microplastics, including plastic bags, bottles, and packaging materials, were dominant, while microplastics were prevalent in sediments and water, and rainfall events significantly increased the transport of plastics into Lake Victoria. The study concluded that effective drainage management required the integration of structural maintenance, proper waste collection, community engagement, and regulatory enforcement. Recommendations included strengthening routine cleaning, enhancing public awareness, addressing encroachment, improving institutional capacity, and implementing monitoring programs to reduce plastic pollution in Nakivubo Channel and Lake Victoria.