Cooper (Chapman) Lake: 81.4% full as of 2026-08-11
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 | 2026-08-11 | 81.4 | 437.20 | 246,358 | 210,583 | 258,723 | 16,387 |
| Yesterday | 2026-08-10 | 81.6 | 437.24 | 247,014 | 211,239 | 258,723 | 16,410 |
| 2 days ago | 2026-08-09 | 81.9 | 437.28 | 247,671 | 211,896 | 258,723 | 16,433 |
| 1 week ago | 2026-08-04 | 83.4 | 437.51 | 251,466 | 215,691 | 258,723 | 16,566 |
| 1 month ago | 2026-07-11 | 87.7 | 438.18 | 262,694 | 226,919 | 258,723 | 16,951 |
| 3 months ago | 2026-05-11 | 80.8 | 437.11 | 244,886 | 209,111 | 258,723 | 16,335 |
| 6 months ago | 2026-02-11 | 68.7 | 435.11 | 213,454 | 177,679 | 258,723 | 15,025 |
| 1 year ago | 2025-08-11 | 95.4 | 439.33 | 282,568 | 246,793 | 258,723 | 17,612 |
*
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 | 2026-08-11 17:00 | 437.19 | 440.00 | -2.81 |
| 1 hour prior | 2026-08-11 16:00 | 437.18 | 440.00 | -2.82 |
| 2 hours prior | 2026-08-11 15:00 | 437.18 | 440.00 | -2.82 |
| 6 hours prior | 2026-08-11 11:00 | 437.21 | 440.00 | -2.79 |
| 12 hours prior | 2026-08-11 05:00 | 437.21 | 440.00 | -2.79 |
| 24 hours prior | 2026-08-10 17:00 | 437.22 | 440.00 | -2.78 |
| 48 hours prior | 2026-08-09 17:00 | 437.27 | 440.00 | -2.73 |
*
Data is provisional and subject to revision.
Additional Information
| Impoundment date | 1991-01-01 |
| Vertical datum | NGVD29 |
| Dead pool elevation | 415.50 ft above NGVD29 |
| Emergency spillway crest elevation | 446.20 ft above NGVD29 |
| Flood pool elevation | 446.20 ft above NGVD29 |
| Maximum design elevation | 459.50 ft above NGVD29 |
| Top of dam elevation | 464.50 ft above NGVD29 |
| Conservation pool elevation | 440.00 ft above NGVD29 |
| Data download (CSV) | period of record, last one year, last 30 days |
Elevation-Area-Capacity Curves
1991-01-01 (source: USGS)
2007-07-01 (source: TWDB)
: GIS Data
2022-07-01 (source: TWDB)
: GIS Data
|
|
| Data Source | USGS:07342495 |
| USGS Monitoring Location | USGS:07342495 |
Lake Location
