Recent efforts to understand microplastic (MP) transport dynamics in aquatic and terrestrial systems have focused on pathways connected to roadways and impervious surface runoff. Detention basins,located adjacent to these surfaces, potentially serve as primary sinks, capturing MPs before they infiltrate groundwater resources. This research examines the role of algae mats and sediment in detention basins as sinks for MPs in urban areas over the Edwards Aquifer recharge zone. Algae and sediment samples were collected in September 2022 and September 2024. Samples were processed using a standardized protocol for MP purification, isolation, and extraction. MP items were identified and characterized using Fourier transform infrared spectroscopy. Fibers were the most abundant morphotype, accounting for approximately 93% of all MPs, while the remaining 7% consisted of fragments, films, and foams. Cellulose acetate comprised about 50% of all characterized MPs and 42% of all fibers. The majority of fibers were composed of cellulose acetate (45%), polyester (20%), and rayon (12%). While other MPs were identified in significantly lower quantities, their presence is concerning due to their association with carcinogens. Additional results and implications will be discussed during the presentation.