Tennessee Valley Authority

Flood Control Activities

The Tennessee River watershed has one of the highest annual rainfall totals of any watershed in the U.S., averaging 50.6 inches per year. During 2025, approximately 55.1 inches of rain fell in the Tennessee Valley. TVA manages the Tennessee River system in an integrated manner, which includes managing minimum river flows and minimum depths for navigation, reducing flood damage, generating low-cost hydroelectric power, maintaining flows that support habitat for fish and other aquatic species, maintaining water supply, and providing recreational opportunities for the Tennessee Valley. In addition, having cool water available helps TVA to meet thermal compliance and support normal operation of TVA's nuclear and fossil-fueled plants, while oxygenating water helps fish species remain healthy. TVA spills or releases excess water through its dams in order to reduce flood damage to the Tennessee Valley. TVA typically spills only when all available hydroelectric generating turbines are operating at full capacity and additional water still needs to be moved downstream.

The Tennessee Valley experienced just above normal rainfall at 109 percent of normal and runoff at 98 percent of normal during 2025. Although runoff for 2025 was below normal due to fewer significant rain events, the winter and spring timing of above normal rainfall during the period supported TVA's objective to generate low-cost hydroelectric power while also meeting its river system commitments, including flood mitigation, which is estimated to have prevented damages across the Tennessee Valley of approximately $90 million in 2025 and $10.2 billion over TVA's recorded history.