Freshwater ecosystems are experiencing disproportionate levels of pollution and ecological deterioration in response to climate change and the continuously expanding human population. Anthropogenic activities contribute a variety of stressors, including altered land use, nutrient loading, and hydrologic modification, that influence stream macroinvertebrate community composition and the ecosystem processes they support. Hydrologic regimes are also essential predictors of ecosystem function, shaping benthic macroinvertebrate community structures and organic matter (OM) dynamics. In streams, terrestrial OM represents a predominant energy source and forms the foundation of many aquatic food webs. Prior studies have shown that environmental conditions influence the relative contributions of biological and physical factors driving OM decomposition. To better understand these dynamics, we conducted a 140-day leaf-pack study in 18 streams across the Tennessee River watershed, representing a range of human land use (e.g., urban, agriculture, and forest) and flow intermittency. This study aims to differentiate the contributions of shredding macroinvertebrates, physical abrasion via stream flow, and microbial activity to OM decomposition rates (k). We will use a structural equation model (SEM) to quantify the relative importance of each factor under varying environmental conditions. We hypothesize that in streams with greater human land use, microbial activity will be the dominant driver of decomposition due to nutrient enrichment, increased microbial activity, and reduced macroinvertebrate diversity. Alternatively, we hypothesize that physical abrasion will be the primary driver of decomposition in intermittent streams, where fluctuating flows can mechanically break down leaf material. Lastly, we predict that the drivers of decomposition in perennial, low-impact streams will be more variable and context-dependent, reflecting intact ecological interactions. Understanding the factors that regulate OM decomposition is critical because these processes underpin nutrient cycling, energy flow, and overall ecosystem resilience. Our research will provide insight into the response of freshwater ecosystems to anthropogenic pressures and hydrologic differences, informing conservation and management strategies for maintaining functional aquatic food webs in human-impacted landscapes.