Reservoir · Wyoming · United States · BOR RISE
Guernsey Reservoir
Guernsey Reservoir Dam and Powerplant
12.5% full
Capacity
56.26 hm³
Volume stored
7 hm³
Coordinates
42.289°N, 104.763°W
Last updated
2026-10-08
Current fill
12.5%vs 7 days ago
+0.8%gaining
vs 1 year ago
-4.4%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: 2026-10-08.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 42.289, -104.763 · Open in Google Maps
About Guernsey Reservoir
As of October 8, 2026, Guernsey Reservoir is filled to 12.5% of its total capacity, holding roughly 7 hm³ of water out of a maximum 56 hm³. At this level the reservoir is critically low.
Over the most recent week on record the fill level has held broadly steady (+0.8 pts), and it is 4.4 points below its level on the same date a year earlier.
Across the readings we hold for Guernsey Reservoir — 1944 data points between October 10, 2021 and October 8, 2026 — the level has ranged from a low of 1.2% (October 10, 2021) to a high of 84.7% (January 13, 2024). 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 42.289°N, 104.763°W.
Key facts
- Current fill level
- 12.5%
- Water stored
- 7 hm³
- Total capacity
- 56 hm³
- 7-day change
- ▲ 0.8 pts
- Year-on-year
- ▼ 4.4 pts
- Primary use
- Multipurpose
- River basin
- Wyoming
- Operator
- BOR
- Coordinates
- 42.289°N, 104.763°W
- Last updated
- October 8, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 8 Oct 2026 | 12.5% | 7 |
| 7 Oct 2026 | 12.4% | 7 |
| 6 Oct 2026 | 12.3% | 7 |
| 5 Oct 2026 | 12.2% | 7 |
| 4 Oct 2026 | 12.1% | 7 |
| 3 Oct 2026 | 12.0% | 7 |
| 2 Oct 2026 | 11.9% | 7 |
| 1 Oct 2026 | 11.7% | 7 |
| 30 Sep 2026 | 11.7% | 7 |
| 29 Sep 2026 | 11.5% | 6 |
| 28 Sep 2026 | 11.4% | 6 |
| 27 Sep 2026 | 11.3% | 6 |