Quantifying Riverine Plastic Pollution Using Participatory Science and Trash Traps

Abstract Local governments and environmental nonprofits are increasingly using trash traps to intercept and remove escaped plastics and other litter from stormwater systems and surface waters. In this paper, we demonstrate the utility of these devices for collecting data that provide insights into riverine litter sources and solutions. Between 2021 and 2024, seven Waterkeeper organizations in North Carolina maintained 21 in‐stream trash traps in watersheds across the state and trained staff and volunteers to record the types and quantities of litter during cleanouts. Over this period, Waterkeeper organizations and their volunteers documented 150,750 pieces of litter captured by traps. Captured litter overwhelmingly comprised plastic that floats and is resistant to biodegradation. Litter accumulation rates were moderately positively correlated with the percentages of developed land and impervious surface as well as road and ambient population density in the associated watershed. In some traps, litter accumulation rates were also positively correlated with precipitation rates. Beyond understanding riverine plastic pollution, this paper also provides insights on challenges and opportunities that arise from using trash traps to collect data on riverine litter.