Reservoir · Oklahoma · United States · USGS NWIS
Lake Hefner
76.5% full
Capacity
91.77 hm³
Volume stored
70 hm³
Coordinates
35.583°N, 97.596°W
Last updated
2026-09-30
Current fill
76.5%vs 7 days ago
+5.4%gaining
vs 1 year ago
-22.1%year-over-year
7-day trend
↑rising
Data source: USGS National Water Information System (NWIS) — daily reservoir storage volume. Capacity is the design (normal full-pool) capacity from the US National Inventory of Dams (NID); fill % = current volume ÷ design capacity. Last reading: 2026-09-30.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 35.583, -97.596 · Open in Google Maps
About Lake Hefner
As of September 30, 2026, Lake Hefner is filled to 76.5% of its total capacity, holding roughly 70 hm³ of water out of a maximum 92 hm³. At this level the reservoir is within its normal operating range.
Over the most recent week on record the fill level has risen by 5.4 percentage points, and it is 22.1 points below its level on the same date a year earlier.
Across the readings we hold for Lake Hefner — 1461 data points between October 1, 2022 and September 30, 2026 — the level has ranged from a low of 71.1% (September 23, 2026) to a high of 105.0% (July 12, 2023). On average the reservoir is fullest around February and at its lowest around October.
It is operated by USGS primarily for multiple purposes. It lies within the Oklahoma basin at 35.583°N, 97.596°W.
Key facts
- Current fill level
- 76.5%
- Water stored
- 70 hm³
- Total capacity
- 92 hm³
- 7-day change
- ▲ 5.4 pts
- Year-on-year
- ▼ 22.1 pts
- Primary use
- Multipurpose
- River basin
- Oklahoma
- Operator
- USGS
- Coordinates
- 35.583°N, 97.596°W
- Last updated
- September 30, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 30 Sep 2026 | 76.5% | 70 |
| 29 Sep 2026 | 75.5% | 69 |
| 28 Sep 2026 | 74.5% | 68 |
| 27 Sep 2026 | 73.5% | 67 |
| 26 Sep 2026 | 72.5% | 67 |
| 25 Sep 2026 | 71.8% | 66 |
| 24 Sep 2026 | 71.2% | 65 |
| 23 Sep 2026 | 71.1% | 65 |
| 22 Sep 2026 | 71.4% | 66 |
| 21 Sep 2026 | 71.7% | 66 |
| 20 Sep 2026 | 72.0% | 66 |
| 19 Sep 2026 | 72.3% | 66 |