<p>Microplastic (MP) pollution in reservoirs is gaining growing global attention. This study presents the first assessment of MP pollution in the surface waters and sediments of three dam reservoirs in northwest Tunisia, providing valuable baseline data for understanding MP pollution in managed freshwater systems. To our knowledge, this is the first study of its kind not only in Tunisia but also in North Africa, addressing a significant data gap in the global understanding of MPs in freshwater environments. Extracted MPs were categorized by type, color, and size. Representative particles from the three sites were analyzed using Fourier Transform Infrared Spectroscopy in attenuated total reflectance mode (FTIR-ATR) to identify polymer composition. Results showed that MP concentrations ranged from 10.5 to 12.38 items L⁻¹ in surface waters and from 157.44 to 316.12 items kg⁻¹ dry weight (dw) in sediments, highlighting significant pollution in these reservoirs. Sediment contamination was More severe in urban areas. MPs Mainly identified in three types as fibres, fragments, and films, appearing in various colors, including black, clear, blue, red, green, and white. Fibres were the Most common type in both matrices. MP sizes ranged from 0.1 to 5&#xa0;mm, with particles between 0.1 and 0.5 mm being the most dominant, suggesting potential risks to aquatic life. FTIR-ATR analysis revealed polyethylene as the most abundant polymer (66.67%), followed by polypropylene (33.33%). These findings contribute to the global discourse on freshwater MP pollution, emphasizing the need for further monitoring and mitigation strategies in reservoir ecosystems worldwide.</p>