Cooper (Chapman) Lake water level today
On Oct 28, 2026, Cooper (Chapman) Lake is at 434.26 ft, 63.8% full (5.74 ft below full pool). That is 8.5 points below normal for this date.
Lowest since October 2022Low
Source: Texas Water Development Board · storage 165,159 of 258,723 acre-ft · provisional data
Cooper (Chapman) Lake percent full history
Percent full Normal range (10th–90th percentile, 1996–2025) Average
Cooper (Chapman) Lake from space
The same area near the lowest and the highest level since 2016, on clear days. Compare the shoreline and the coves.
Imagery: NASA GIBS, Harmonized Landsat Sentinel-2 (HLS). Landsat 8/9 courtesy of NASA/USGS; contains modified Copernicus Sentinel data 2022, 2025. Black specks are cloud and shadow masks.
Records and key dates
- Record high
- 100.0%Nov 7, 2000
- Record low
- 15.3%Dec 28, 2006
- 12-month high
- 90.1%Jun 24, 2026
- 12-month low
- 63.8%Oct 28, 2026
- Last time full
- Jul 20, 2025
- Change in 1 year
- −2.64 ft−15.7 pts
About Cooper (Chapman) Lake
- River basin
- Sulphur
- Full pool (top of conservation pool)
- 440.00 ft
- Conservation capacity
- 258,723 acre-ft
- Surface area today
- 14,440 acres
- Dead pool elevation
- 415.50 ft
- Flood control reservoir
- Yes
- Data since
- Oct 1, 2000
Monthly average, last 10 years
Average percent full each month.
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026 | 71% | 73% | 77% | 79% | 82% | 87% | 87% | 80% | 72% | 67% | — | — |
| 2025 | 77% | 100% | 100% | 100% | 100% | 100% | 100% | 94% | 88% | 82% | 76% | 75% |
| 2024 | 91% | 100% | 100% | 100% | 100% | 100% | 99% | 94% | 87% | 81% | 77% | 73% |
| 2023 | 86% | 97% | 100% | 100% | 100% | 100% | 100% | 97% | 89% | 85% | 90% | 88% |
| 2022 | 76% | 74% | 72% | 82% | 88% | 86% | 80% | 74% | 71% | 64% | 68% | 85% |
| 2021 | 92% | 96% | 100% | 100% | 100% | 100% | 100% | 97% | 93% | 88% | 85% | 81% |
| 2020 | 91% | 99% | 100% | 100% | 100% | 99% | 96% | 89% | 83% | 78% | 75% | 72% |
| 2019 | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 94% | 93% | 88% | 87% | 87% |
| 2018 | 89% | 91% | 100% | 100% | 97% | 93% | 86% | 78% | 78% | 97% | 100% | 100% |
| 2017 | 76% | 76% | 75% | 79% | 80% | 80% | 87% | 94% | 98% | 93% | 90% | 88% |
Frequently asked questions
Is Cooper (Chapman) Lake full?
Not quite. On Oct 28, 2026 Cooper (Chapman) Lake was 63.8% full, 5.74 feet below its full pool elevation of 440.00 ft. It was last full on Jul 20, 2025.
What is the normal level of Cooper (Chapman) Lake for this time of year?
Between 1996 and 2025, Cooper (Chapman) Lake averaged 72.3% full around Oct 28, and 8 in 10 years it was between 33.3% and 100.0%. Today it is −8.5 percentage points below that average.
What is the lowest Cooper (Chapman) Lake has been?
In the TWDB record, which starts in 2000, the lowest daily value was 15.3% on Dec 28, 2006. The highest was 100.0% on Nov 7, 2000.
How often is the Cooper (Chapman) Lake water level updated?
TWDB publishes one reading per day for each reservoir. We check for new data every 2 hours and show the date of the reading next to the level. Recent values are provisional.
What does percent full mean?
It is the water stored in the conservation pool divided by the conservation capacity (258,723 acre-feet for Cooper (Chapman) Lake). Water above the conservation pool is flood storage and is not counted, so a reservoir can show 100% while rising into its flood pool.