Lake J.B. Thomas: 21.9% full as of 2026-08-26
Historical Data
| Date | Percent Full |
Mean Water Level (ft) |
Reservoir Storage (acre-ft) |
Conservation Storage (acre-ft) |
Conservation Capacity (acre-ft) |
Surface Area (acres) |
|
|---|---|---|---|---|---|---|---|
| Today | 2026-08-26 | 21.9 | 2,227.28 | 44,487 | 43,814 | 199,931 | 3,211 |
| Yesterday | 2026-08-25 | 22.0 | 2,227.31 | 44,584 | 43,911 | 199,931 | 3,214 |
| 2 days ago | 2026-08-24 | 22.0 | 2,227.36 | 44,744 | 44,071 | 199,931 | 3,218 |
| 1 week ago | 2026-08-19 | 22.4 | 2,227.56 | 45,390 | 44,717 | 199,931 | 3,236 |
| 1 month ago | 2026-07-26 | 24.1 | 2,228.62 | 48,871 | 48,198 | 199,931 | 3,337 |
| 3 months ago | 2026-05-26 | 25.1 | 2,229.23 | 50,926 | 50,253 | 199,931 | 3,403 |
| 6 months ago | 2026-02-26 | 28.8 | 2,231.31 | 58,259 | 57,586 | 199,931 | 3,655 |
| 1 year ago | 2025-08-26 | 35.8 | 2,234.92 | 72,318 | 71,645 | 199,931 | 4,126 |
*
Percent Full is based on Conservation Storage and Conservation Capacity and doesn't account for storage in flood pool.
**
Values above, including today's are averaged conditions. For near real-time instantaneous water level, see table below or the interactive map viewer.
Most Recent Instantaneous Water Level
| Date/time |
Water Level (ft) |
Conservation Pool Elevation (ft) |
Height Above Conservation Pool (ft) |
|
|---|---|---|---|---|
| Most recent | 2026-08-26 20:45 | 2,227.27 | 2,258.00 | -30.73 |
| 1 hour prior | 2026-08-26 19:45 | 2,227.27 | 2,258.00 | -30.73 |
| 2 hours prior | 2026-08-26 18:45 | 2,227.28 | 2,258.00 | -30.72 |
| 6 hours prior | 2026-08-26 14:45 | 2,227.29 | 2,258.00 | -30.71 |
| 12 hours prior | 2026-08-26 08:45 | 2,227.28 | 2,258.00 | -30.72 |
| 24 hours prior | 2026-08-25 20:45 | 2,227.30 | 2,258.00 | -30.70 |
| 48 hours prior | 2026-08-24 20:45 | 2,227.34 | 2,258.00 | -30.66 |
*
Data is provisional and subject to revision.
Additional Information
| Impoundment date | 1952-01-01 |
| Vertical datum | NGVD29 |
| Dead pool elevation | 2,200.00 ft above NGVD29 |
| Service spillway crest elevation | 2,258.00 ft above NGVD29 |
| Emergency spillway crest elevation | 2,264.00 ft above NGVD29 |
| Emergency spillway crest elevation | 2,267.00 ft above NGVD29 |
| Maximum design elevation | 2,275.00 ft above NGVD29 |
| Top of dam elevation | 2,280.00 ft above NGVD29 |
| Conservation pool elevation | 2,258.00 ft above NGVD29 |
| Data download (CSV) | period of record, last one year, last 30 days |
| Data Source | USGS:08118000 |
| USGS Monitoring Location | USGS:08118000 |
Lake Location
