Flood Storage

TVA's series of dams and reservoirs is well designed to hold back floodwater as well as to provide many other benefits to the citizens of the Tennessee Valley.

TVA's series of dams and reservoirs are designed to hold back floodwater to protect 15 communities that are prone to flooding:

  • Kingsport, Tenn.
  • Elizabethton, Tenn.
  • Clinton, Tenn.
  • Knoxville, Tenn.
  • Lenoir City, Tenn.
  • McCaysville, Ga./Copperhill, Tenn.
  • Chattanooga, Tenn.
  • South Pittsburg, Tenn.
  • Huntsville, Ala.
  • Decatur, Ala.
  • Florence, Ala.
  • Shelbyville, Tenn.
  • Fayetteville, Tenn.
  • Savannah, Tenn.
  • Paducah, Ky.

Flood storage and the potential for flooding vary throughout the year. From early winter to late spring, the reservoir system has the capacity to store 11 million acre-feet of water—volume equal to 1 foot of water covering 11 million acres. During the summer, a capacity of 5 million acre-feet is maintained to reduce flooding caused by summer storms.

Flood Storage Upstream of Chattanooga

Chattanooga is the most flood-prone city in the Tennessee Valley because the city sits just above the narrow gorge where the Tennessee River passes through the Cumberland Mountains. Before there was a TVA, high river flow would reach the bottleneck of the mountain gorge, slow and start to backup—flooding Chattanooga at least once a year.

Throughout the eastern Tennessee Valley and upstream of Chattanooga, 32 dams (24 TVA, four Duke Energy and four Brookfield Smoky Mountain Hydropower) work collectively to protect Chattanooga. The seven tributary workhorses of the reservoir system providing the most flood storage are:

  • 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 Reservoir on the Hiwassee River
  • Hiwassee Reservoir on the Hiwassee River
  • Nottely Reservoir on the Nottely River

Flood Storage Below Chattanooga

Kentucky Reservoir, near the mouth of the Tennessee River 207 miles upstream of Pickwick Landing Dam, has 4 million acre-feet of flood storage space during the winter and early spring. This represents more than 40 percent of the flood storage in the entire TVA reservoir system. This capacity can be used to reduce flood crests on the Mississippi River at Cairo, Ill., by as much as two to three feet.

More About Storage

Three other main-river reservoirs upstream from Kentucky but below Chattanooga—Pickwick Landing, Wheeler and Guntersville—provide about 1 million acre-feet of storage space. This is used to supplement storage in Kentucky Reservoir and to reduce flooding immediately downstream of these dams.

Storage space in main-river reservoirs is limited by topography and the requirement in the TVA Act for an 11-foot waterway for commercial navigation from the beginning of the Tennessee River at Knoxville, Tenn., to its mouth at Paducah, Ky.

Chattanooga’s Biggest Flood

The largest flood in Chattanooga's history occurred in March 1867, before the TVA system was created. The flood crested at 58 feet and completely inundated the city. Since the completion of the reservoir system, the highest Chattanooga flood stage was nearly 37 feet, which occurred in 1973. Without regulation, the flood would have reached 52.4 feet. 

The Unified Development of the Tennessee River plan stressed TVA was to provide flood control, navigation and electricity for the region. TVAs dams are tangible evidence of its primary mission: improving life in the Tennessee Valley. We’re celebrating the plan with an in-depth look at 32 of the dams it comprises.