Reservoir · Wyoming · United States · BOR RISE
Boysen Reservoir
Boysen Reservoir Dam and Powerplant
70.5% full
Capacity
865.3 hm³
Volume stored
610 hm³
Coordinates
43.400°N, 108.177°W
Last updated
2026-09-09
Current fill
70.5%vs 7 days ago
-0.9%losing
vs 1 year ago
-6.1%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. 43.400, -108.177 · Open in Google Maps
About Boysen Reservoir
As of September 9, 2026, Boysen Reservoir is filled to 70.5% of its total capacity, holding roughly 610 hm³ of water out of a maximum 865 hm³. At this level the reservoir is within its normal operating range.
Over the most recent week on record the fill level has held broadly steady (-0.9 pts), and it is 6.1 points below its level on the same date a year earlier.
Across the readings we hold for Boysen Reservoir — 1956 data points between September 12, 2021 and September 9, 2026 — the level has ranged from a low of 70.5% (September 8, 2026) to a high of 105.0% (June 17, 2023). On average the reservoir is fullest around July and at its lowest around May.
It is operated by BOR primarily for multiple purposes. It lies within the Wyoming basin at 43.400°N, 108.177°W.
Key facts
- Current fill level
- 70.5%
- Water stored
- 610 hm³
- Total capacity
- 865 hm³
- 7-day change
- ▼ 0.9 pts
- Year-on-year
- ▼ 6.1 pts
- Primary use
- Multipurpose
- River basin
- Wyoming
- Operator
- BOR
- Coordinates
- 43.400°N, 108.177°W
- Last updated
- September 9, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 9 Sep 2026 | 70.5% | 610 |
| 8 Sep 2026 | 70.5% | 610 |
| 7 Sep 2026 | 70.7% | 612 |
| 6 Sep 2026 | 70.8% | 613 |
| 5 Sep 2026 | 71.0% | 614 |
| 4 Sep 2026 | 71.1% | 616 |
| 3 Sep 2026 | 71.2% | 616 |
| 2 Sep 2026 | 71.4% | 618 |
| 1 Sep 2026 | 71.5% | 618 |
| 31 Aug 2026 | 71.5% | 619 |
| 30 Aug 2026 | 71.6% | 620 |
| 29 Aug 2026 | 71.7% | 621 |