Drought Conditions and Reservoir Impact Dashboard

TVA uses any rainfall events to store as much water as possible in reservoirs. However, prolonged drought and lack of rainfall make filling reservoirs more challenging. For questions about docks and shoreline structures, see Shoreline & Dock Permits.

Shoreline & Dock Permits

TVA balances competing demands on the system, including flood damage reduction, navigation, power production, water supply, water quality and recreation. During drought, TVA adjusts river operations as needed to help balance flows with reservoir levels for water supply and water quality needs, releasing water conservatively to meet downstream commitments.

Drought can affect TVA’s generation portfolio. Lower flows can result in lower-than-planned hydrogeneration and present challenges with maintaining thermal compliance at coal and nuclear sites. Increased cooling tower use can be likely at nuclear sites, and the threat of derates can increase if available cooling is not sufficient to maintain thermal compliance. (A derate is a temporary reduction in the maximum output of a generating unit.)

A reservoir’s water level depends on rainfall and runoff. The flood guide represents a target level that the reservoir could be allowed to fill to, or temporarily exceed, in the interest of storing large amounts of water during flood conditions. TVA maintains levels as close to the flood guide as possible, but there are often not enough large rain events during the summer to support stable, high-water levels for the entire summer period. Water levels during the summer often drift below the flood guide targets as the water released is required to meet downstream water supply and water quality demands across the Tennessee River system.

Flood guides are designed as targets to maintain an appropriate level of storage in a tributary reservoir, so the reservoir is ready to store excess water during large floods and help protect communities below the dam. The flood guide varies seasonally as the risk of flooding changes throughout the year. Flood guides are lower in the winter because that is the time of year when the flood risk is greatest.

An operating range represents an upper and lower seasonal bound for the main stem Tennessee River reservoirs and the smaller run-of-river dams. It addresses the same seasonal flood risk while also allowing for day-to-day pool fluctuations within the range. Those fluctuations help ensure reservoir flexibility, which accommodates other objectives like maintaining water supply, river depth for commercial navigation and maximizing hydropower generation.

On this page, a reservoir with a published operating range is shown as being at normal elevation any time its level is inside that range.

Rainfall and runoff patterns significantly affect actual reservoir levels compared with published operating targets. TVA works to maintain levels along the main stem Tennessee River, and at certain tributary reservoirs like Boone, within the published operating guide. During periods of prolonged drought, it may not be possible to maintain water levels according to the operating guide until the reservoir receives adequate rainfall and runoff.

Tributary reservoirs may also fall well below the expected ranges because of prolonged drought, as water is released to fulfill minimum flow requirements despite low inflow. Even without drought conditions, it can be normal for tributary reservoir levels to decline through the summer because that is the time of year when water demands are highest and inflows are lowest.

No. TVA operates an integrated river system and does not move water from one reservoir to fill another. The large tributary reservoirs provide substantial flow and volume from June 1 through Labor Day, and that water is used to meet flow requirements related to water quality and water supply needs.