Overgrowth and detachment of aquatic vegetation (AV) can result in serious disruptions to water and energy infrastructure. Early warning of the potential for such events would benefit river managers in planning and preparing resources in case responses are needed. Several potential drivers of this growth include - but not limited to - hydroclimate, land use/management, biological interactions, and river operations. However, long-term data on the presence and distribution of AV is required to identify these drivers, and observational data from the reservoir are not always available. Using medium resolution historical satellite data, we constructed long-term time series to identify potential occurrences of AV at or near the surface in a large river reservoir managed by the Tennessee Valley Authority that has experienced recent issues with AV overgrowth and detachment. The seasonal and inter-annual variation in spatial distributions and magnitude of AV reflect a dynamic system, both within the reservoir and when compared to other reservoirs along the Tennessee River. These dynamics may be related to a combination of climate and watershed factors. Information obtained through remote sensing augments limited field data and addresses key gaps in the understanding of spatial and temporal patterns of AV growth.