Lake J.B. Thomas: 41.8% full as of 2025-01-14

The elevation-storage rating curve used to produce the storage hydrograph is made of two segments: (1) the segment up to the conservation pool top (below the red line) is based on measured data, and (2) the segment in the flood pool (above the red line) is an extrapolation from the first segment and shouldn't be relied upon for flood storage information.

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 2025-01-14 41.8 2,237.71 84,273 83,600 199,931 4,450
Yesterday 2025-01-13 41.8 2,237.72 84,317 83,644 199,931 4,452
2 days ago 2025-01-12 41.9 2,237.74 84,406 83,733 199,931 4,454
1 week ago 2025-01-07 42.1 2,237.82 84,763 84,090 199,931 4,465
1 month ago 2024-12-14 42.8 2,238.16 86,289 85,616 199,931 4,509
3 months ago 2024-10-14 37.1 2,235.52 74,815 74,142 199,931 4,195
6 months ago 2024-07-14 18.7 2,225.23 38,101 37,428 199,931 3,011
1 year ago 2024-01-14 21.8 2,227.18 44,166 43,493 199,931 3,202
*

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 2025-01-14 13:45 2,237.71 2,258.00 -20.29
1 hour prior 2025-01-14 12:45 2,237.71 2,258.00 -20.29
2 hours prior 2025-01-14 11:45 2,237.71 2,258.00 -20.29
6 hours prior 2025-01-14 07:45 2,237.70 2,258.00 -20.30
12 hours prior 2025-01-14 01:45 2,237.71 2,258.00 -20.29
24 hours prior 2025-01-13 13:45 2,237.72 2,258.00 -20.28
48 hours prior 2025-01-12 13:45 2,237.74 2,258.00 -20.26
*

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

Lake Location