Nickajack Lake Water Level
Tennessee · Tennessee River
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Water level history
About Nickajack Lake
Nickajack Lake is a reservoir on the Tennessee River in Tennessee, operated by Tennessee Valley Authority. It replaced the leaky Hales Bar Dam just upstream. Its full summer pool sits at 634 ft above sea level. Live water levels come from the Tennessee Valley Authority (TVA) and update hourly.
Understanding Nickajack Lake's water level
Nickajack is a mainstem run-of-river reservoir on the Tennessee River, the sixth step in the Tennessee Valley Authority's stairway of dams and locks, and it does not behave like a storage lake. Water typically takes only three or four days to pass through, which is short enough that the reservoir never stratifies: the column stays mixed and oxygenated top to bottom. There is no annual fill and drawdown cycle to explain a change in level here. What you see instead is short-term movement driven by generation, by lockages, and by what Chickamauga Dam is releasing 46 miles upstream.
One unusual load sits right on this pool. Raccoon Mountain, TVA's pumped-storage plant, pumps water out of Nickajack up to a 528-acre reservoir on top of the mountain during low demand, then runs it back down through four units rated at 1,700 megawatts when demand climbs. Filling the upper reservoir takes about 28 hours and holds roughly 12 billion gallons. Nickajack's own four units are good for about 107 megawatts, and the 110-by-600-foot lock can raise nine large barges at a time, carrying grain, wood chips, salt, petroleum, steel and coal.
The dam exists because its predecessor failed. Hales Bar, six miles upstream, was the first main-river multipurpose dam on the Tennessee, begun in 1905 and finally finished in 1913 after employing more than five thousand workers. It was built on cavernous limestone and leaked almost immediately. Engineers pumped hot asphalt into the foundation in 1919, and by 1931 it was still losing around a thousand cubic feet per second. TVA inherited the problem in 1939, spent more than three million dollars on repairs, and gave up. Nickajack was built on sounder rock between 1964 and 1967, Hales Bar's spillway was demolished, and its powerhouse still stands as a marina. The 1967 impoundment also drowned part of the entrance to Nickajack Cave, which now shelters an endangered gray bat colony from late April into October and is reachable only by water.
Nickajack Lake — frequently asked
Does Nickajack Lake have a seasonal drawdown?
No. Nickajack is a run-of-river mainstem reservoir, so TVA passes water through rather than storing it seasonally. It usually takes only three or four days for water to flow from one end of the reservoir to the other. Unlike TVA's tributary storage lakes, it does not follow an annual summer-fill and winter-drawdown cycle.
Why does Nickajack's level change during the day?
Three things move it: generation at Nickajack's own four units, releases arriving from Chickamauga Dam 46 miles upstream, and Raccoon Mountain. The pumped-storage plant draws water out of Nickajack to fill its mountaintop reservoir when power demand is low and sends it back down when demand rises, which is a large intraday load on this pool.
What was Hales Bar Dam and why was it replaced?
Hales Bar was the first main-river multipurpose dam on the Tennessee River, begun in 1905 and completed in 1913. It was founded on cavernous limestone and leaked from the start. Hot asphalt was pumped into the foundation in 1919, and by 1931 it was still leaking around a thousand cubic feet per second. TVA acquired it in 1939, spent over three million dollars trying to seal it, then built Nickajack downstream on better rock and demolished the Hales Bar spillway.
Can you still see Hales Bar Dam?
The powerhouse survives. TVA demolished the spillway during 1967 and 1968 but left the powerhouse standing, and it is now part of Hales Bar Marina, about six miles upstream of Nickajack Dam. It sits at the downstream end of the Tennessee River Gorge.
What is Nickajack Cave?
A cave on the reservoir that is home to a roosting colony of endangered gray bats between late April and early October. Filling the reservoir in 1967 raised the water over part of the entrance, cutting its height roughly in half and leaving it accessible only by boat. A boardwalk from the Maple View day use area leads to an observation platform overlooking the entrance, so you can watch the evening emergence without disturbing the colony.
What is the fishing like on Nickajack?
Redear sunfish and bluegill are outstanding, redear typically running seven to nine inches. Largemouth carry a 15-inch minimum, spotted bass none in the upper zone, and crappie fish better in the lower reservoir. Smallmouth are good in the upper end and the tailwaters. State biologists flag Alabama Bass hybrids as a current concern because they are outcompeting native species.
Other lakes near Nickajack Lake
- Normandy LakeTN
- Melton Hill LakeTN
- Norris LakeTN
- Kentucky LakeKY/TN
- Old Hickory LakeTN
- J. Percy Priest LakeTN
See current levels for all 23 Tennessee lakes and reservoirs →
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