Beneath the Surface: Assessing the Spatio-Temporal Distribution of Microplastics in Lake Champlain and its Tributaries

Microplastics are an increasing concern in the environment, with global plastic production growing at an annual rate of 8.4% from 1950 to 2015. Once discarded, plastics fragment into smaller pieces, including microplastics (<5 mm), which enter ecosystems through land-cover runoff, wastewater effluent, airborne deposition, and improper disposal. These particles accumulate in rivers, lakes, and other waterbodies, potentially affecting aquatic organisms and ecosystem health. This research investigates microplastic pathways, distribution, and loading in Lake Champlain and its tributaries, and retention within local fish communities. Preliminary surveys in 2024 sampled five New York tributaries, while 2025 efforts focused specifically on the Saranac and Ausable Rivers. Historic whole-lake samples from the Long Term Monitoring Program (1992–2025) were analyzed to determine microplastic concentrations across 15 lake stations. Data from previous wastewater treatment plant surveys (2016–2018) across New York and Vermont were used to assess post-treatment effluent contributions. Approximately 103 fish from Lake Champlain were examined to quantify microplastic retention. Results indicate fibers are the dominant microplastic type in New York rivers and across Lake Champlain, with more urbanized areas, especially the Saranac River, contributing the greatest quantities. Wastewater treatment plants were significant microplastic sources, with particle morphology varying by facility. Fish results revealed primarily fibrous microplastic retention in digestive tracts. By identifying pathways, distributions, and retention patterns, this research establishes a baseline for microplastic contamination in the basin and provides information to guide management and public awareness initiatives.