Great Falls Dam (Tennessee)

Great Falls Dam is a hydroelectric dam on the Caney Fork, straddling the county line between White County and Warren County in the U.S. state of Tennessee. It is the only dam outside the Tennessee River watershed owned and operated by the Tennessee Valley Authority. The dam impounds the Great Falls Lake, and its tailwaters feed into Center Hill Lake.Tennessee Valley Authority
Great Falls Reservoir
Retrieved: January 29, 2009. The completion of Great Falls Dam in late 1916 was an engineering triumph, marking the first successful attempt to impound the volatile and flood-prone Caney Fork. The dam is also notable for its design, utilizing a mostly underground conduit to carry water from the reservoir via a tributary to the Power House downstream from the dam.Tennessee Valley Authority, ''Design of TVA Projects Volume 3: Mechanical Design of Hydro Plants'', Technical Report No. 24 (Washington, D.C.: Tennessee Valley Authority, 1952), pp. 301-302.

Great Falls Dam is named for the rapids and waterfalls on the Caney Fork downstream from the dam. The section of river below the Power House is world-renowned for whitewater kayaking. The dam and its tailwaters are surrounded by Rock Island State Park.

Location

Great Falls Dam is located approximately above the mouth of the Caney Fork, immediately downstream from the Caney Fork's confluence with the Collins River. The confluence of these two rivers (the Collins flowing from the southwest and the Caney Fork from the east) creates a peninsula. The two rivers nearly meet at the ''Narrows'', a "land bridge" connecting the peninsula to the mainland. Two tunnels measuring approximately each deliver water from the Collins River section of the Great Falls Reservoir underneath Highway 287 at the ''Narrows'' to the dam's powerhouse located on the Caney Fork downstream from the dam.

Great Falls Reservoir stretches behind the dam for along the Caney Fork and for roughly along the lower Collins River. The lake also includes a small stretch of the lower Rocky River, which empties into the Caney Fork about a mile east of the dam.

Capacity

Great Falls Dam is a concrete gravity diversion type dam high and long, and has a generating capacity of 33,800 kilowatts (33.8 MW). The dam's spillway has 18 gates with a combined discharge of per second.Tennessee Valley Authority, ''The Nickajack Project: A Report on the Planning, Design, Construction, Initial Operations, and Costs'', Technical Report No. 16 (Knoxville, Tenn.: Tennessee Valley Authority, 1972), pp. 10-11. Great Falls Reservoir has approximately of flood storage, of shoreline, and of water surface.

History

Throughout the 19th century, entrepreneur after entrepreneur attempted to harness the extraordinary hydro power potential of the Caney Fork only to be defeated by one of the volatile river's disastrous floods. The first major establishment to utilize the river's power at Great Falls was the Bosson Mill, a gristmill and carding factory that operated at the site across the river from the Power House from the 1860s until its destruction by a flood in 1882. The most prominent venture at Great Falls Gorge was the Falls City Cotton Mill Company, which established a cotton mill and company town, ''Falls City,'' just above the gorge in 1892. The company turned a moderate profit until 1902, when the Good Friday Flood destroyed its toll bridge and powerhouse, and the mill was forced to close (the mill and the town's "spring castle" are still standing, however).

By 1900, the rise of major industry in Nashville brought an increased demand for electricity. In 1901, Nashville entrepreneur Arthur Dyer formed the Great Falls Power Company and purchased land on the north side of the gorge with plans to build a dam. Dyer had trouble getting financing for the project, however, and in 1912 sold Great Falls Power to the Tennessee Power Company. The original plans called for a dam high. At the ''Narrows'', where the two tunnels are now located, an open channel was to be made from the Collins River to the Caney Fork. The water was to be carried across the gorge in a steel flume and then in an open canal across Horseshoe Bend, a distance of . The powerhouse was to be located at least by river below the present powerhouse. In so doing a total head of would have been available; at the dam, between the dam and the present powerhouse and around horseshoe bend.

With financing from Chicago business interests, Tennessee Power began construction work on the dam's foundation. Within a month, however, the Caney Fork burst its banks again, flooding out the project's excavation work and destroying its cofferdams. Tennessee Power again struggled with finances, but was able to resume construction in 1915 and by late 1916, the high dam had been completed. The plant went into operation on January 1, 1917.

In 1922, the Tennessee Power Company merged with several other entities to form the Tennessee Electric Power Company (TEPCO). TEPCO tripled the capacity of Great Falls Dam by raising the dam and installing a second generator at the powerhouse downstream. The dam faced its first major test in March 1929, when several cloudbursts atop the Cumberland Plateau caused the Caney Fork to expand to record flood volumes, sending wreckage and uprooted trees crashing into the dam. The Great Falls Power House was flooded and a substation was destroyed, but the dam held.

The passage of the TVA Act in 1933 gave the Tennessee Valley Authority oversight of flood control operations in the Tennessee River watershed, where most of TEPCO's dams were located. Jo Conn Guild, the head of TEPCO, vehemently opposed TVA and challenged the constitutionality of the TVA Act in federal court. After the U.S. Supreme Court upheld the act, however, TEPCO was forced under eminent domain to sell its assets to TVA for $78 million. This sum included $3.5 million for Great Falls Dam.

After its acquisition, TVA almost immediately began making improvements to Great Falls Dam. By 1946, grouting work had repaired much of the leakage through the cliffside, which had been an issue since the dam's creation. TVA also built a new switchyard and control building. In the late 1960s, the agency leased part of the Great Falls reservation to the state of Tennessee for the development of Rock Island State Park, which opened in 1969.Tennessee State Parks
Rock Island State Park official park brochure
Retrieved: January 29, 2009. PDF.

References

External links

— official TVA site
Rock Island State Park
— official site

{{Tennessee Valley Authority Facilities

Buildings and structures in White County, Tennessee
Buildings and structures in Warren County, Tennessee
Dams in Tennessee
Dams on the National Register of Historic Places in Tennessee
Dams completed in 1917
Energy infrastructure completed in 1917
Historic districts on the National Register of Historic Places in Tennessee
Hydroelectric power plants in Tennessee
Tennessee Valley Authority dams
National Register of Historic Places in Warren County, Tennessee
1917 establishments in Tennessee