Cooper (Chapman) Lake: 78.5% full as of 2026-08-21
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 | 2026-08-21 | 78.5 | 436.74 | 238,881 | 203,106 | 258,723 | 16,123 |
| Yesterday | 2026-08-20 | 78.7 | 436.77 | 239,365 | 203,590 | 258,723 | 16,140 |
| 2 days ago | 2026-08-19 | 79.0 | 436.82 | 240,173 | 204,398 | 258,723 | 16,169 |
| 1 week ago | 2026-08-14 | 80.4 | 437.05 | 243,907 | 208,132 | 258,723 | 16,301 |
| 1 month ago | 2026-07-21 | 86.9 | 438.05 | 260,495 | 224,720 | 258,723 | 16,876 |
| 3 months ago | 2026-05-21 | 82.0 | 437.29 | 247,836 | 212,061 | 258,723 | 16,439 |
| 6 months ago | 2026-02-21 | 78.9 | 436.80 | 239,850 | 204,075 | 258,723 | 16,157 |
| 1 year ago | 2025-08-21 | 92.9 | 438.96 | 276,091 | 240,316 | 258,723 | 17,400 |
*
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 | 2026-08-21 16:00 | 436.72 | 440.00 | -3.28 |
| 1 hour prior | 2026-08-21 15:00 | 436.72 | 440.00 | -3.28 |
| 2 hours prior | 2026-08-21 14:00 | 436.71 | 440.00 | -3.29 |
| 6 hours prior | 2026-08-21 10:00 | 436.73 | 440.00 | -3.27 |
| 12 hours prior | 2026-08-21 04:00 | 436.74 | 440.00 | -3.26 |
| 24 hours prior | 2026-08-20 16:00 | 436.76 | 440.00 | -3.24 |
| 48 hours prior | 2026-08-19 16:00 | 436.81 | 440.00 | -3.19 |
*
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
