Ninetynine Island Reservoir water level — South Carolina
Ninetynine Island Reservoir in South Carolina was last measured at 509.45 ft (datum NAVD88), as of Aug 31, 2026, 4:00 AM (UTC-04:00) (USGS Water Services). Over its recent trend window the level has been rising (+1.1 ft). This reading is provisional and subject to revision.
- % of conservation pool full
- Not reported
- Storage
- Not reported
- Recent trend
- ↑Rising
+1.1 ft over the trend window
Recent trend
Readings this station published between Jun 2, 2026 and Aug 31, 2026 — a 89-day window — downsampled for display.
Data: USGS Water Services (waterservices.usgs.gov) and USACE CWMS Data (cwms-data.usace.army.mil), retrieved 2026-08-31. Both public domain (a work of the U.S. Government, 17 U.S.C. §105).
Source: USGS site 02153550, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00). Official page for this lake →
About this gauge's record
This site's drainage basin covers approximately 1,550 sq mi of contributing watershed.
The dam behind Ninetynine Island Reservoir
Ninetynine Island Reservoir is held back by Ninety Nine Islands , a concrete structure , standing 72 ft high and running 1,568 ft along its crest , built across Broad in Cherokee County , near Lockhart . It was completed in 1909 , and is owned by Duke Energy (a public utility owner) , to a design credited to SOUTHERN POWER COMPANY.
Its recorded primary purpose is hydroelectric — releases follow generation schedules, so the level can move on a daily cycle that has nothing to do with drought .
It is founded on rock, with a concrete core. Its spillway is ungated: once the pool reaches the crest, water leaves on its own and the operator cannot hold it back. The spillway opening is 891 ft wide.
NID classes it high hazard potential. That describes what a failure would cost downstream — loss of life would be expected — and says nothing about how likely a failure is, or what condition the dam is in. Its most recent condition assessment was satisfactory — no deficiencies recognised for expected loading. That assessment is dated 04/11/2023.
At its normal pool the reservoir covers about 350 acres. NID records a maximum storage of 2,300 acre-ft against a normal storage of 2,300 acre-ft. Its maximum discharge capacity is 145,000 cubic feet per second.
Dam facts: National Inventory of Dams record SC01074 , filed by Federal Energy Regulatory Commission — U.S. Army Corps of Engineers, public domain. Water levels above come from USGS Water Services and are a separate source. (How this dam was matched to this gauge →)
How Ninetynine Island Reservoir compares nearby
5 of 6 nearby lakes with a current trend are also rising right now.
Nearby lakes
The six nearest published lakes by centroid distance (great-circle) — cross-state neighbors included.
| Lake | State | Level | Distance |
|---|---|---|---|
| Lake Blalock | SC | 710.11 ft | 34 km |
| Neal Shoals Reservoir | SC | 332.68 ft | 41 km |
| Lake William C. Bowen | SC | 814.73 ft | 51 km |
| Tyger Lake | SC | 710.95 ft | 52 km |
| Monticello Reservoir | SC | 423.06 ft | 83 km |
| Lake Greenwood | SC | 438.45 ft | 103 km |
Frequently asked questions
- What is the current water level of Ninetynine Island Reservoir?
- As of Aug 31, 2026, 4:00 AM (UTC-04:00), the pool elevation was 509.45 ft (datum NAVD88), provisional and subject to revision. See the trend chart above for the recent direction.
- Is Ninetynine Island Reservoir full right now?
- Its managing agency does not publish a %-of-conservation-pool-full figure for this lake, so we show the bare level rather than estimate one.
- Where does this data come from?
- From USGS site 02153550, retrieved Aug 31, 2026, 8:24 AM (UTC+00:00).
More in South Carolina
See every lake tracked in South Carolina, or read the methodology behind these figures.