Lake J.B. Thomas: 21.0% full as of 2026-09-09
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 | 2026-09-09 | 21.0 | 2,226.73 | 42,734 | 42,061 | 199,931 | 3,163 |
| Yesterday | 2026-09-08 | 21.1 | 2,226.75 | 42,798 | 42,125 | 199,931 | 3,165 |
| 2 days ago | 2026-09-07 | 21.1 | 2,226.80 | 42,956 | 42,283 | 199,931 | 3,169 |
| 1 week ago | 2026-09-02 | 21.5 | 2,226.99 | 43,560 | 42,887 | 199,931 | 3,185 |
| 1 month ago | 2026-08-09 | 23.1 | 2,228.01 | 46,854 | 46,181 | 199,931 | 3,275 |
| 3 months ago | 2026-06-09 | 25.3 | 2,229.31 | 51,199 | 50,526 | 199,931 | 3,412 |
| 6 months ago | 2026-03-09 | 28.5 | 2,231.15 | 57,676 | 57,003 | 199,931 | 3,634 |
| 1 year ago | 2025-09-09 | 35.2 | 2,234.62 | 71,086 | 70,413 | 199,931 | 4,091 |
*
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 | 2026-09-09 05:45 | 2,226.72 | 2,258.00 | -31.28 |
| 1 hour prior | 2026-09-09 04:45 | 2,226.72 | 2,258.00 | -31.28 |
| 2 hours prior | 2026-09-09 03:45 | 2,226.72 | 2,258.00 | -31.28 |
| 6 hours prior | 2026-09-08 23:45 | 2,226.73 | 2,258.00 | -31.27 |
| 12 hours prior | 2026-09-08 17:45 | 2,226.74 | 2,258.00 | -31.26 |
| 24 hours prior | 2026-09-08 05:45 | 2,226.76 | 2,258.00 | -31.24 |
| 48 hours prior | 2026-09-07 05:45 | 2,226.80 | 2,258.00 | -31.20 |
*
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
