Lake J.B. Thomas: 20.4% full as of 2026-10-26

Historical Data

Date Percent Full Mean Water Level
(ft) 		Reservoir Storage
(acre-ft) 		Conservation Storage
(acre-ft) 		Conservation Capacity
(acre-ft) 		Surface Area
(acres)
Most recent 2026-10-26 20.4 2,226.33 41,477 40,804 199,931 3,126
1 day prior 2026-10-25 20.4 2,226.34 41,508 40,835 199,931 3,126
2 days prior 2026-10-24 20.5 2,226.36 41,570 40,897 199,931 3,128
1 week prior 2026-10-19 20.5 2,226.42 41,758 41,085 199,931 3,134
1 month prior 2026-09-26 20.1 2,226.15 40,916 40,243 199,931 3,108
3 months prior 2026-07-26 24.1 2,228.62 48,871 48,198 199,931 3,337
6 months prior 2026-04-26 26.4 2,229.95 53,405 52,732 199,931 3,485
1 year prior 2025-10-26 33.1 2,233.57 66,861 66,188 199,931 3,953
*

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 2026-10-26 22:45 2,226.33 2,258.00 -31.67
1 hour prior 2026-10-26 21:45 2,226.33 2,258.00 -31.67
2 hours prior 2026-10-26 20:45 2,226.33 2,258.00 -31.67
6 hours prior 2026-10-26 16:45 2,226.32 2,258.00 -31.68
12 hours prior 2026-10-26 10:45 2,226.32 2,258.00 -31.68
24 hours prior 2026-10-25 22:45 2,226.33 2,258.00 -31.67
48 hours prior 2026-10-24 22:45 2,226.35 2,258.00 -31.65
*

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

Elevation-Area-Capacity Curves

1952-01-01 (source: USGS)
1999-11-01 (source: TWDB) : GIS Data
Data Source USGS:08118000
USGS Monitoring Location USGS:08118000

Lake Location