Reservoir · Washington · United States · BOR RISE
Potholes Reservoir
Potholes Reservoir and O'Sullivan Dam
10.9% full
Capacity
631.17 hm³
Volume stored
69 hm³
Coordinates
46.983°N, 119.276°W
Last updated
2026-09-30
Current fill
10.9%vs 7 days ago
+0.7%gaining
vs 1 year ago
+0.8%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: 2026-09-30.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 46.983, -119.276 · Open in Google Maps
About Potholes Reservoir
As of September 30, 2026, Potholes Reservoir is filled to 10.9% of its total capacity, holding roughly 69 hm³ of water out of a maximum 631 hm³. At this level the reservoir is critically low.
Over the most recent week on record the fill level has held broadly steady (+0.7 pts), and it sits close to where it was a year earlier.
Across the readings we hold for Potholes Reservoir — 2148 data points between October 2, 2021 and September 30, 2026 — the level has ranged from a low of 4.9% (September 3, 2025) to a high of 77.3% (May 17, 2026). On average the reservoir is fullest around May and at its lowest around September.
It is operated by BOR primarily for multiple purposes. It lies within the Washington basin at 46.983°N, 119.276°W.
Key facts
- Current fill level
- 10.9%
- Water stored
- 69 hm³
- Total capacity
- 631 hm³
- 7-day change
- ▲ 0.7 pts
- Year-on-year
- ▲ 0.8 pts
- Primary use
- Multipurpose
- River basin
- Washington
- Operator
- BOR
- Coordinates
- 46.983°N, 119.276°W
- Last updated
- September 30, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 30 Sep 2026 | 10.9% | 69 |
| 29 Sep 2026 | 11.0% | 69 |
| 28 Sep 2026 | 10.9% | 69 |
| 27 Sep 2026 | 10.8% | 68 |
| 26 Sep 2026 | 10.6% | 67 |
| 25 Sep 2026 | 10.5% | 66 |
| 24 Sep 2026 | 10.4% | 66 |
| 23 Sep 2026 | 10.2% | 64 |
| 22 Sep 2026 | 10.5% | 66 |
| 21 Sep 2026 | 10.5% | 66 |
| 20 Sep 2026 | 10.4% | 66 |
| 19 Sep 2026 | 10.4% | 66 |