The amount of space allocated for flood storage in the TVA reservoir system varies with the time of year and potential flood threat. From January 1 through March 15, the system has the capacity to store about 10 million acre-feet of water. That’s a volume equal to one foot of water covering 10 million acres of land. A storage capacity of about five million acre-feet, including 3.3 million acre-feet in Kentucky Reservoir, is maintained during the summer to reduce flooding caused by summer storms.

Flood storage above Chattanooga

The reservoir system in the eastern portion of the Tennessee Valley was primarily planned to protect Chattanooga from flooding. At least one reservoir was built on each of the five major tributary rivers above Chattanooga, and these have enough space to store the floodwaters from large storms in the drainage area above them.

These seven reservoirs do the main work in controlling floods:

Norris Reservoir on the Clinch River
Fontana Reservoir on the Little Tennessee River
Douglas Reservoir on the French Broad River
Cherokee Reservoir on the Holston River
Chatuge, Nottely, and Hiwassee Reservoirs in the Hiwassee River basin.

Targeted Flood Storage above Chattanooga

January 1 chart showing planned flood storage

Limited—but important—flood storage space is also available in three main-river reservoirs above Chattanooga: Fort Loudoun/Tellico, Watts Bar, and Chickamauga.

Together, these reservoirs give TVA nearly five million acre-feet of storage during the winter flood season.

Flood storage below Chattanooga

Kentucky Reservoir, near the mouth of the Tennessee River, has four million acre-feet of flood storage space during the winter and early spring. This represents more than 40 percent of the available flood storage in the entire TVA reservoir system. This capacity can be used to reduce flood crests on the Mississippi River at Cairo, Illinois, by as much as two to three feet. Learn more about averting flood damages on the Ohio and Mississippi Rivers.

The other main-river reservoirs upstream from Kentucky but below Chattanooga (Pickwick, Wilson, Wheeler, and Guntersville) provide about one million acre-feet of storage space. This is used to supplement storage in Kentucky Reservoir and to reduce flooding immediately below these dams. Storage space in main-river reservoirs is limited by topography and the requirement in the TVA Act to provide a 9-foot waterway for commercial navigation from the beginning of the Tennessee River at Knoxville, Tennessee, to its mouth at Paducah, Kentucky.