Reservoir · Montana · United States · BOR RISE
Lake Elwell
Lake Elwell and Tiber Dam
86.5% full
Capacity
1,193.17 hm³
Volume stored
1032 hm³
Coordinates
48.318°N, 111.091°W
Last updated
2026-09-09
Current fill
86.5%vs 7 days ago
-0.1%losing
vs 1 year ago
+10.4%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: 2026-09-09.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 48.318, -111.091 · Open in Google Maps
About Lake Elwell
As of September 9, 2026, Lake Elwell is filled to 86.5% of its total capacity, holding roughly 1,032 hm³ of water out of a maximum 1,193 hm³. At this level the reservoir is high.
Over the most recent week on record the fill level has held broadly steady (-0.1 pts), and it is 10.4 points above its level on the same date a year earlier.
Across the readings we hold for Lake Elwell — 1993 data points between September 12, 2021 and September 9, 2026 — the level has ranged from a low of 70.3% (February 20, 2025) to a high of 96.3% (July 5, 2026). On average the reservoir is fullest around July and at its lowest around March.
It is operated by BOR primarily for multiple purposes. It lies within the Montana basin at 48.318°N, 111.091°W.
Key facts
- Current fill level
- 86.5%
- Water stored
- 1,032 hm³
- Total capacity
- 1,193 hm³
- 7-day change
- ▼ 0.1 pts
- Year-on-year
- ▲ 10.4 pts
- Primary use
- Multipurpose
- River basin
- Montana
- Operator
- BOR
- Coordinates
- 48.318°N, 111.091°W
- Last updated
- September 9, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 9 Sep 2026 | 86.5% | 1,032 |
| 8 Sep 2026 | 86.3% | 1,030 |
| 7 Sep 2026 | 86.4% | 1,031 |
| 6 Sep 2026 | 86.3% | 1,030 |
| 5 Sep 2026 | 86.4% | 1,031 |
| 4 Sep 2026 | 86.4% | 1,031 |
| 3 Sep 2026 | 86.5% | 1,033 |
| 2 Sep 2026 | 86.6% | 1,034 |
| 1 Sep 2026 | 86.8% | 1,035 |
| 31 Aug 2026 | 86.9% | 1,037 |
| 30 Aug 2026 | 87.1% | 1,039 |
| 29 Aug 2026 | 87.2% | 1,041 |