Great Falls Lake Water Level
Tennessee · Caney Fork River
Full pool is the summer level. Great Falls Lake is drawn down about 15 ft to roughly 785 ft over winter for flood storage, so a lower reading outside the summer season is usually scheduled rather than drought.
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Water level history
About Great Falls Lake
Great Falls Lake is a reservoir on the Caney Fork River in Tennessee, operated by Tennessee Valley Authority. It's the only TVA dam outside the Tennessee River watershed. Its full summer pool sits at 800 ft above sea level. Live water levels come from the Tennessee Valley Authority (TVA) and update hourly.
Understanding Great Falls Lake's water level
Great Falls is the odd one out in the TVA system, and not for the reason usually given. It is the only TVA dam outside the Tennessee River watershed: the Caney Fork drains to the Cumberland, not the Tennessee. It is also very old, begun in 1915 and generating from 1 January 1917, built by the Tennessee Power Company and acquired by TVA in 1939 as part of the Tennessee Electric Power Company purchase. It is listed on the National Register of Historic Places, so even maintenance requires historical review.
The hydraulics are genuinely strange. Water is taken from the Collins River side, through dual 650-foot steel penstocks drilled straight through the mountain, to a powerhouse on the Caney Fork about three quarters of a mile below the dam. When the generators run, the Collins can briefly flow backwards. The turbines are air-cooled, which is rare in TVA hydro; operators open windows and bay doors to keep the century-old units in temperature. The dam itself mostly handles flood water, with eighteen radial gates.
As a single-purpose power project with limited flood storage, Great Falls moves a lot. TVA's summer pool is 800 feet and the normal minimum is 785, but month-to-month swings of ten to fifteen feet are ordinary within that range. The record maximum is 817.48 feet from 23 March 1929 and the record minimum 756.3 feet from 19 August 1918, both from a record beginning in 1917. Below the dam, Rock Island State Park occupies the gorge between the dam and the powerhouse, and this is where the level matters most: the powerhouse typically releases at some point every day at irregular times, the gorge closes whenever a discharge is likely, and the state warns that releases may come with or without warning. Swimming and wading below the powerhouse are prohibited at all times because of hidden currents.
Great Falls Lake — frequently asked
Is Great Falls the oldest dam in the TVA system?
No, though the claim is common. Ocoee No. 1, completed in 1911, is TVA's oldest dam and reservoir. Great Falls was completed in 1916 and began generating on 1 January 1917, making it among the oldest but not the oldest. Its real distinction is being the only TVA dam outside the Tennessee River watershed, since the Caney Fork drains to the Cumberland.
What is Great Falls Lake's normal pool elevation?
TVA gives a summer pool of 800 feet above sea level and a normal minimum pool of 785 feet, so the working range is about fifteen feet. The figure of 805 feet that circulates is the top of the spillway gates, not an operating target. Within the normal range, month-to-month swings of ten to fifteen feet are ordinary for a single-purpose power project like this one.
How dangerous is the gorge below Great Falls Dam?
Enough that Tennessee State Parks closes it routinely. The dam and the powerhouse sit about half a mile apart and release independently, the powerhouse typically releases at some point every day at irregular times, and the state warns that releases may occur with or without warning. All gorge areas downstream close when a discharge is likely. Swimming and wading below the powerhouse are prohibited at all times because of hidden currents.
What are Great Falls Lake's record levels?
The record maximum is 817.48 feet on 23 March 1929 and the record minimum is 756.3 feet on 19 August 1918, from a record that begins in January 1917. The largest known flood at the dam site was 210,000 cubic feet per second in March 1929, which is also when the record pool was set.
Why does the Collins River sometimes flow backwards here?
Because of how the plant is plumbed. Water is drawn from the Collins River side of the reservoir through two 650-foot penstocks bored through the mountain to a powerhouse on the Caney Fork below the dam. When the generators are running hard, that draw is enough to briefly reverse flow on the Collins. The dam itself is mostly a flood-control structure rather than the intake.
What is at Rock Island State Park?
The park sits where the Caney Fork, Collins and Rocky rivers meet, at the head of Center Hill Lake. Great Falls itself is a thirty-foot waterfall below the ruins of the 1892 Falls City Cotton Mill, which are on the National Register. Twin Falls, on the north shore, exists because the reservoir raised the Collins and forced water through caverns to emerge on the far side. Over 153 bird species have been recorded.
Other lakes near Great Falls Lake
- J. Percy Priest LakeTN
- Fort Loudoun LakeTN
- Kentucky LakeKY/TN
- Douglas LakeTN
- Melton Hill LakeTN
- Dale Hollow LakeKY/TN
See current levels for all 23 Tennessee lakes and reservoirs →
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