Anthropogenic changes to the environment impact aquatic ecosystems by modifying resource availability, which could influence community composition and function. Studies suggest a positive relationship between diversity and ecosystem functioning, with more diverse systems being more resilient. Some individuals are particularly sensitive to nutrient shifts in the environment. Organisms that indicate change in the environment are valuable because they shed light on humans’ impact on the ecosystem. Diatoms are useful bioindicators of water quality, as they respond to environmental conditions like nutrient inputs.To test the effect of nutrient availability on diatom community composition, we deployed nutrient diffusing substrate at four stream sites before and after nutrient rich tributaries. We used seven nutrient treatments including macronutrients phosphorus and nitrogen, along with micronutrients molybdenum and zinc with a control at each of the four sites. We expect the phosphorus treatments to select for fast growing taxa, and for the magnitude of this effect to be less at sites with higher background nutrient concentrations. Preliminary results indicate that tributaries upstream and downstream of nutrient rich tributaries have unique algal communities. Results from this experiment will provide insight into how stream communities respond to anthropogenic influences.