Reservoir · Idaho · United States · BOR RISE
Anderson Ranch Reservoir
Anderson Ranch Reservoir, Dam, and Powerplant
50.5% full
Capacity
572.6 hm³
Volume stored
289 hm³
Coordinates
43.360°N, 115.450°W
Last updated
2026-09-30
Current fill
50.5%vs 7 days ago
-0.4%losing
vs 1 year ago
-1.6%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. 43.360, -115.450 · Open in Google Maps
About Anderson Ranch Reservoir
As of September 30, 2026, Anderson Ranch Reservoir is filled to 50.5% of its total capacity, holding roughly 289 hm³ of water out of a maximum 573 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 (-0.4 pts), and it is 1.6 points below its level on the same date a year earlier.
Across the readings we hold for Anderson Ranch Reservoir — 2192 data points between October 2, 2021 and September 30, 2026 — the level has ranged from a low of 29.8% (February 8, 2022) to a high of 89.1% (May 14, 2026). On average the reservoir is fullest around June and at its lowest around November.
It is operated by BOR primarily for multiple purposes. It lies within the Idaho basin at 43.360°N, 115.450°W.
Key facts
- Current fill level
- 50.5%
- Water stored
- 289 hm³
- Total capacity
- 573 hm³
- 7-day change
- ▼ 0.4 pts
- Year-on-year
- ▼ 1.6 pts
- Primary use
- Multipurpose
- River basin
- Idaho
- Operator
- BOR
- Coordinates
- 43.360°N, 115.450°W
- Last updated
- September 30, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 30 Sep 2026 | 50.5% | 289 |
| 29 Sep 2026 | 50.6% | 290 |
| 28 Sep 2026 | 50.7% | 290 |
| 27 Sep 2026 | 50.7% | 290 |
| 26 Sep 2026 | 50.8% | 291 |
| 25 Sep 2026 | 50.8% | 291 |
| 24 Sep 2026 | 50.9% | 291 |
| 23 Sep 2026 | 50.9% | 292 |
| 22 Sep 2026 | 51.0% | 292 |
| 21 Sep 2026 | 51.0% | 292 |
| 20 Sep 2026 | 51.0% | 292 |
| 19 Sep 2026 | 51.1% | 292 |