Trash accumulation in aquatic ecosystems disrupts natural processes and introduces both physical and chemical challenges to water bodies. Urban streams, which tend to have high nutrient loads, may support high rates of biofilm growth, but biofilms require stable surfaces for growth and these may be scarce in streams with high sediment loads. Trash can offer alternative substrates, influencing biofilm community structure and metabolic activity. This study examines how biofilm growth and metabolism vary across common types of trash substrates in streams, such as organic waste, plastics, metals, and glass. In spring 2024, a pilot will refine methods by testing various substrate attachment techniques (e.g., hot glue vs. alligator clips) and incubation times. At SFS, I intend to present the results of the pilot study. Trash substrates, including fritted glass discs (control), orange peels, plastic bottles, aluminum, and steel cans, will be incubated in Goose Creek, an urban stream in southeastern PA. After four weeks, biofilm samples will be incubated to assess metabolic rates, followed by measurement of biomass accumulation. Findings will provide insights into the ecological impacts of trash in streams, informing strategies to mitigate pollution.