Reservoir · Washington · United States · BOR RISE
Potholes Reservoir and O'Sullivan Dam (POT)
27.9% full
Capacity
631.17 hm³
Volume stored
176 hm³
Coordinates
46.983°N, 119.276°W
Last updated
2026-07-28
Current fill
27.9%vs 7 days ago
-0.6%losing
vs 1 year ago
-44.9%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: 2026-07-28.
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 and O'Sullivan Dam (POT)
As of July 28, 2026, Potholes Reservoir and O'Sullivan Dam (POT) is filled to 27.9% of its total capacity, holding roughly 176 hm³ of water out of a maximum 631 hm³. At this level the reservoir is low.
Over the most recent week on record the fill level has held broadly steady (-0.6 pts), and it is 44.9 points below its level on the same date a year earlier.
Across the readings we hold for Potholes Reservoir and O'Sullivan Dam (POT) — 2147 data points between July 31, 2021 and July 28, 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
- 27.9%
- Water stored
- 176 hm³
- Total capacity
- 631 hm³
- 7-day change
- ▼ 0.6 pts
- Year-on-year
- ▼ 44.9 pts
- Primary use
- Multipurpose
- River basin
- Washington
- Operator
- BOR
- Coordinates
- 46.983°N, 119.276°W
- Last updated
- July 28, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 28 Jul 2026 | 27.9% | 176 |
| 27 Jul 2026 | 28.5% | 180 |
| 26 Jul 2026 | 29.5% | 186 |
| 25 Jul 2026 | 30.2% | 191 |
| 24 Jul 2026 | 30.9% | 195 |
| 23 Jul 2026 | 31.7% | 200 |
| 22 Jul 2026 | 32.6% | 206 |
| 21 Jul 2026 | 33.5% | 211 |
| 20 Jul 2026 | 34.1% | 215 |
| 19 Jul 2026 | 34.8% | 220 |
| 18 Jul 2026 | 35.7% | 226 |
| 17 Jul 2026 | 36.4% | 230 |
Frequently asked questions
What is the current water level of Potholes Reservoir and O'Sullivan Dam (POT)?
As of July 28, 2026, Potholes Reservoir and O'Sullivan Dam (POT) is at 27.9% of its capacity, holding approximately 176 hm³ of water, according to BOR RISE (US Bureau of Reclamation) data.
Is Potholes Reservoir and O'Sullivan Dam (POT) reservoir full?
No. As of July 28, 2026, Potholes Reservoir and O'Sullivan Dam (POT) is low at 27.9% of its capacity, so it is not full.
Is the water level at Potholes Reservoir and O'Sullivan Dam (POT) rising or falling?
The level at Potholes Reservoir and O'Sullivan Dam (POT) has been broadly stable over the latest week on record (-0.6 points).
How much water can Potholes Reservoir and O'Sullivan Dam (POT) hold?
Potholes Reservoir and O'Sullivan Dam (POT) has a total capacity of 631 hm³.
Where is Potholes Reservoir and O'Sullivan Dam (POT) reservoir located?
Potholes Reservoir and O'Sullivan Dam (POT) is located in Washington, United States, within the Washington basin (coordinates 46.983°N, 119.276°W).
What is Potholes Reservoir and O'Sullivan Dam (POT) used for?
Potholes Reservoir and O'Sullivan Dam (POT) is used primarily for multiple purposes, and is managed by BOR.