Reservoir · Wyoming · United States · BOR RISE
Big Sandy Reservoir
Big Sandy Reservoir and Dam
12.3% full
Capacity
48.97 hm³
Volume stored
6 hm³
Coordinates
42.268°N, 109.432°W
Last updated
2026-09-09
Current fill
12.3%vs 7 days ago
-3.6%losing
vs 1 year ago
-21.8%year-over-year
7-day trend
↓falling
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. 42.268, -109.432 · Open in Google Maps
About Big Sandy Reservoir
As of September 9, 2026, Big Sandy Reservoir is filled to 12.3% of its total capacity, holding roughly 6 hm³ of water out of a maximum 49 hm³. At this level the reservoir is critically low.
Over the most recent week on record the fill level has fallen by 3.6 percentage points, and it is 21.8 points below its level on the same date a year earlier.
Across the readings we hold for Big Sandy Reservoir — 1824 data points between September 12, 2021 and September 9, 2026 — the level has ranged from a low of 3.8% (September 12, 2021) to a high of 105.0% (June 5, 2023). On average the reservoir is fullest around June and at its lowest around October.
It is operated by BOR primarily for multiple purposes. It lies within the Wyoming basin at 42.268°N, 109.432°W.
Key facts
- Current fill level
- 12.3%
- Water stored
- 6 hm³
- Total capacity
- 49 hm³
- 7-day change
- ▼ 3.6 pts
- Year-on-year
- ▼ 21.8 pts
- Primary use
- Multipurpose
- River basin
- Wyoming
- Operator
- BOR
- Coordinates
- 42.268°N, 109.432°W
- Last updated
- September 9, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 9 Sep 2026 | 12.3% | 6 |
| 8 Sep 2026 | 12.8% | 6 |
| 7 Sep 2026 | 13.4% | 7 |
| 6 Sep 2026 | 13.9% | 7 |
| 5 Sep 2026 | 14.5% | 7 |
| 4 Sep 2026 | 15.0% | 7 |
| 3 Sep 2026 | 15.5% | 8 |
| 2 Sep 2026 | 15.9% | 8 |
| 1 Sep 2026 | 16.3% | 8 |
| 31 Aug 2026 | 16.6% | 8 |
| 30 Aug 2026 | 17.1% | 8 |
| 29 Aug 2026 | 17.8% | 9 |