Cooper (Chapman) Lake: 73.0% full as of 2026-09-11
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 | 2026-09-11 | 73.0 | 435.85 | 224,772 | 188,997 | 258,723 | 15,559 |
| Yesterday | 2026-09-10 | 73.2 | 435.87 | 225,083 | 189,308 | 258,723 | 15,573 |
| 2 days ago | 2026-09-09 | 73.4 | 435.91 | 225,706 | 189,931 | 258,723 | 15,601 |
| 1 week ago | 2026-09-04 | 74.6 | 436.11 | 228,840 | 193,065 | 258,723 | 15,738 |
| 1 month ago | 2026-08-11 | 81.4 | 437.20 | 246,358 | 210,583 | 258,723 | 16,387 |
| 3 months ago | 2026-06-11 | 86.5 | 437.99 | 259,484 | 223,709 | 258,723 | 16,842 |
| 6 months ago | 2026-03-11 | 77.9 | 436.64 | 237,272 | 201,497 | 258,723 | 16,065 |
| 1 year ago | 2025-09-11 | 88.9 | 438.36 | 265,755 | 229,980 | 258,723 | 17,055 |
*
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 | 2026-09-11 04:00 | 435.84 | 440.00 | -4.16 |
| 1 hour prior | 2026-09-11 03:00 | 435.85 | 440.00 | -4.15 |
| 2 hours prior | 2026-09-11 02:00 | 435.84 | 440.00 | -4.16 |
| 6 hours prior | 2026-09-10 22:00 | 435.84 | 440.00 | -4.16 |
| 12 hours prior | 2026-09-10 16:00 | 435.86 | 440.00 | -4.14 |
| 24 hours prior | 2026-09-10 04:00 | 435.89 | 440.00 | -4.11 |
| 48 hours prior | 2026-09-09 04:00 | 435.92 | 440.00 | -4.08 |
*
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
