Reservoir · Oklahoma · United States · BOR RISE
Foss Reservoir
Foss Reservoir and Dam
85.6% full
Capacity
208.13 hm³
Volume stored
178 hm³
Coordinates
35.550°N, 99.183°W
Last updated
2026-09-09
Current fill
85.6%vs 7 days ago
-0.6%losing
vs 1 year ago
-12.9%year-over-year
7-day trend
→stable
Data source: BOR RISE — US Bureau of Reclamation — 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: 2026-09-09.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 35.550, -99.183 · Open in Google Maps
About Foss Reservoir
As of September 9, 2026, Foss Reservoir is filled to 85.6% of its total capacity, holding roughly 178 hm³ of water out of a maximum 208 hm³. At this level the reservoir is high.
Over the most recent week on record the fill level has held broadly steady (-0.6 pts), and it is 12.9 points below its level on the same date a year earlier.
Across the readings we hold for Foss Reservoir — 1824 data points between September 12, 2021 and September 9, 2026 — the level has ranged from a low of 78.2% (April 24, 2023) to a high of 101.9% (June 18, 2025). On average the reservoir is fullest around July and at its lowest around April.
It is operated by BOR primarily for multiple purposes. It lies within the Oklahoma basin at 35.550°N, 99.183°W.
Key facts
- Current fill level
- 85.6%
- Water stored
- 178 hm³
- Total capacity
- 208 hm³
- 7-day change
- ▼ 0.6 pts
- Year-on-year
- ▼ 12.9 pts
- Primary use
- Multipurpose
- River basin
- Oklahoma
- Operator
- BOR
- Coordinates
- 35.550°N, 99.183°W
- Last updated
- September 9, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 9 Sep 2026 | 85.6% | 178 |
| 8 Sep 2026 | 85.7% | 178 |
| 7 Sep 2026 | 85.8% | 179 |
| 6 Sep 2026 | 85.9% | 179 |
| 5 Sep 2026 | 85.9% | 179 |
| 4 Sep 2026 | 86.0% | 179 |
| 3 Sep 2026 | 86.1% | 179 |
| 2 Sep 2026 | 86.2% | 179 |
| 1 Sep 2026 | 86.3% | 180 |
| 31 Aug 2026 | 86.4% | 180 |
| 30 Aug 2026 | 86.5% | 180 |
| 29 Aug 2026 | 86.6% | 180 |