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Hiwassee powerhouse

Torpedo Testing at Hiwassee

Hiwassee Dam and the reservoir it created are both known for beautiful scenery, canoeing and rafting. But in the 1940s and 50s, Hiwassee also played a key role in serving the nation’s defense.

TVA’s sixth dam built to manage the Tennessee River and generate electricity for the Tennessee Valley, construction on Hiwassee Dam began in 1936 and was completed in 1940. Originally built with only one generating unit, space was reserved in the powerhouse for a second unit, where a reversible pump-turbine was installed in 1956.

Unlike other TVA dams, however, Hiwassee was chosen for a special job—a job that supported a lesser-known part of TVA’s mission as outlined in the TVA Act which was signed by President Franklin D. Roosevelt on May 18, 1933: to provide for the national defense.

“The #1 Arsenal for All Democracy”

Led by the Naval Ordnance Laboratory (NOL) at White Oak, Maryland, the U.S. tested everything from mines to parachute gear at locations around the country as part of its ongoing military preparedness programs. Hiwassee was one of the dams chosen for torpedo testing.

The Navy Bureau of Ordnance chose Hiwassee for torpedo testing because of its reservoir’s deep water—more than 250 feet in places—as well as the isolation provided by its mountainous environs.

The July 1953 issue of All Handsthe Bureau of Naval Personnel Information Bulletin—explained the importance of the testing program:

“This insistence on thorough evaluation is frequently a reflection of the unofficial but often-repeated credo of NOL—that, no matter what its cost, an item of ordnance is valueless if it doesn’t operate properly at the right time and place, and under all service conditions.”

An editorial published in September 1951 in The Knoxville News-Sentinel further demonstrated the importance of the testing taking place at Hiwassee:

“Another important item in a long list of national defense projects in the Tennessee Valley has just been revealed. The Navy for the past nine years has been conducting experiments with rocket-launched missiles and depth charges at Hiwassee Lake, one of TVA’s many water reservoirs.... Thus, thanks to the TVA program, this area more and more has developed into perhaps the No. 1 arsenal for all democracy.”

Another Kind of Test

In 1952, Hiwassee Dam was part of a different kind of test, when TVA decided to test a reverse-drive generator/turbine that could pump water from below the dam up into the reservoir above.

The precursor to TVA’s powerful pumped-storage facility at Raccoon Mountain, Hiwassee Dam Unit 2 was the first of its kind in the United States, and at the time it was the largest and most powerful in the world.

In fact, the unit was so important—not only to TVA but to the entire nation—that it was designated a National Historical Mechanical Engineering Landmark by the American Society of Mechanical Engineers in 1981.

Following a breaker failure in 2011, the pumping abilities were disabled and Unit 2 was used only for power generation through traditional hydro means for several years.

That changed in 2016 when TVA decided to restore the pumping ability, including repairing the breakers, replacing a transformer, exciter and exciter transformer, and repairing the wicket gate brakes.

Service to the Valley

In a speech to the May 1940 meeting of the Tennessee Valley section of the American Society of Civil Engineers, TVA Hiwassee Head Planning Engineer J.S. Bowman said TVA chose Hiwassee as its sixth dam “particularly to assist in flood control for Chattanooga, which is one of the most hazardous situations as regards flood menace in the entire country.”

That commitment to Chattanooga and to the people of the Valley continues today. Hiwassee Dam is a key element of not only TVA’s river management but also power generation, with the dam boasting a net dependable generating capacity of 124 megawatts.