Indiscriminate plastic littering behaviour of inhabitants continues to pose a threat to water bodies with its repercussions on human health and the integrity of the environment. This paper assessed the ecological impact of plastics that are less than 5 mm on the longest dimension, hereinafter called microplastics. Sixty (60) residents were purposively sampled using a snow-balling approach for the study. Questionnaires, field observations of microplastics and sources, fish, and water sediments from the River were the data for the study. Data was analysed with SPSS version 20.0 and presented in tables and figures. Laboratory analysis of microplastics was run on sediments trawled, and on the digestive tracts and gills of fishes caught, all from the River, to assess the accumulation of microplastics. The study revealed that microplastics are present in the River and there is uptake of microplastics by some resident aquatic life which may pose threat to lives. The study further revealed positive correlations between number of fishes and microplastics loads in fish and between microplastic loads in water and loads in fish. Residents are aware of microplastics in the catchment area of the River. The unregulated gutters that flow directly into the River are the main sources. Wind and running water were discovered as the potential ways by which microplastics are deposited into the River. It is therefore recommended that wastewater be treated before reaching the River and gutters should be channelled out of the River where necessary and plastics usage should be regulated and if possible, banned.