Reservoir · Oklahoma · United States · USGS NWIS
Lake Humphreys near Duncan, OK
58.0% full
Capacity
24.76 hm³
Volume stored
14 hm³
Coordinates
34.584°N, 97.886°W
Last updated
2026-07-29
Current fill
58.0%vs 7 days ago
-0.1%losing
vs 1 year ago
-4.0%year-over-year
7-day trend
→stable
Data source: USGS National Water Information System (NWIS) — daily reservoir storage volume. Design capacity is unavailable for this site, so fill % is estimated against the 5-year maximum storage and may overstate fullness. Last reading: 2026-07-29.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 34.584, -97.886 · Open in Google Maps
About Lake Humphreys near Duncan, OK
As of July 29, 2026, Lake Humphreys near Duncan, OK is filled to 58.0% of its total capacity, holding roughly 14 hm³ of water out of a maximum 25 hm³. At this level the reservoir is within its normal operating range.
Over the most recent week on record the fill level has held broadly steady (-0.1 pts), and it is 4.0 points below its level on the same date a year earlier.
Across the readings we hold for Lake Humphreys near Duncan, OK — 1449 data points between July 30, 2022 and July 29, 2026 — the level has ranged from a low of 47.9% (October 16, 2023) to a high of 100.0% (May 2, 2025). On average the reservoir is fullest around May and at its lowest around January.
It is operated by USGS primarily for multiple purposes. It lies within the Oklahoma basin at 34.584°N, 97.886°W.
Key facts
- Current fill level
- 58.0%
- Water stored
- 14 hm³
- Total capacity
- 25 hm³
- 7-day change
- ▼ 0.1 pts
- Year-on-year
- ▼ 4.0 pts
- Primary use
- Multipurpose
- River basin
- Oklahoma
- Operator
- USGS
- Coordinates
- 34.584°N, 97.886°W
- Last updated
- July 29, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 29 Jul 2026 | 58.0% | 14 |
| 28 Jul 2026 | 58.1% | 14 |
| 27 Jul 2026 | 58.1% | 14 |
| 26 Jul 2026 | 58.3% | 14 |
| 25 Jul 2026 | 58.5% | 14 |
| 24 Jul 2026 | 58.6% | 15 |
| 23 Jul 2026 | 58.7% | 15 |
| 22 Jul 2026 | 59.0% | 15 |
| 21 Jul 2026 | 59.2% | 15 |
| 20 Jul 2026 | 59.2% | 15 |
| 19 Jul 2026 | 59.2% | 15 |
| 18 Jul 2026 | 59.4% | 15 |
Frequently asked questions
What is the current water level of Lake Humphreys near Duncan, OK?
As of July 29, 2026, Lake Humphreys near Duncan, OK is at 58.0% of its capacity, holding approximately 14 hm³ of water, according to USGS NWIS data.
Is Lake Humphreys near Duncan, OK reservoir full?
No. As of July 29, 2026, Lake Humphreys near Duncan, OK is within its normal operating range at 58.0% of its capacity, so it is not full.
Is the water level at Lake Humphreys near Duncan, OK rising or falling?
The level at Lake Humphreys near Duncan, OK has been broadly stable over the latest week on record (-0.1 points).
How much water can Lake Humphreys near Duncan, OK hold?
Lake Humphreys near Duncan, OK has a total capacity of 25 hm³.
Where is Lake Humphreys near Duncan, OK reservoir located?
Lake Humphreys near Duncan, OK is located in Oklahoma, United States, within the Oklahoma basin (coordinates 34.584°N, 97.886°W).
What is Lake Humphreys near Duncan, OK used for?
Lake Humphreys near Duncan, OK is used primarily for multiple purposes, and is managed by USGS.