Reservoir · Montana · United States · BOR RISE
Helena Valley Reservoir
Helena Valley Reservoir and Dam
87.7% full
Capacity
12.89 hm³
Volume stored
11 hm³
Vs month average
100% of normal
Coordinates
46.638°N, 111.882°W
Last updated
2026-10-28
Current fill
87.7%vs 7 days ago
-0.7 pplosing
vs 1 year ago
+0.3 ppyear-over-year
7-day trend
→stable
Drought context
Storage vs October average
100%of normal
87.7% full on 2026-10-28, against an average of 87.5% for October across 6 years of readings (+0.2 points).
Drought Monitor at this site · 27 October 2026
Nonenot in a drought category
Helena Valley Reservoir's coordinates fall outside every category on the weekly U.S. Drought Monitor map. That describes local conditions — rainfall, soil moisture, streamflow — not the reservoir's storage. Montana drought figures →
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: 2026-10-28.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 46.638°N, 111.882°W · Open in Google Maps
About Helena Valley Reservoir
As of October 28, 2026, Helena Valley Reservoir is filled to 87.7% of its total capacity, holding 11.31 hm³ of water out of a maximum 12.89 hm³. At this level the reservoir is high.
Over the most recent week on record the fill level has held broadly steady (-0.7 pp), and it sits close to where it was a year earlier.
Across the readings we hold for Helena Valley Reservoir — 1825 data points between October 30, 2021 and October 28, 2026 — the level has ranged from a low of 60.6% (April 15, 2025) to a high of 99.7% (July 2, 2023). On average the reservoir is fullest around May and at its lowest around March.
It is operated by BOR primarily for multiple purposes. It is at 46.638°N, 111.882°W.
Key facts
- Current fill level
- 87.7% of total capacity
- Water stored
- 11.31 hm³
- Total capacity
- 12.89 hm³
- 7-day change
- ▼ 0.7 pp
- Year-on-year
- ▲ 0.3 pp
- Primary use
- Multipurpose
- Operator
- BOR
- Coordinates
- 46.638°N, 111.882°W
- Last updated
- October 28, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 28 Oct 2026 | 87.7% | 11.31 |
| 27 Oct 2026 | 87.8% | 11.32 |
| 26 Oct 2026 | 88.0% | 11.34 |
| 25 Oct 2026 | 88.1% | 11.35 |
| 24 Oct 2026 | 88.2% | 11.37 |
| 23 Oct 2026 | 88.4% | 11.39 |
| 22 Oct 2026 | 88.3% | 11.38 |
| 21 Oct 2026 | 88.4% | 11.39 |
| 20 Oct 2026 | 88.4% | 11.4 |
| 19 Oct 2026 | 88.6% | 11.42 |
| 18 Oct 2026 | 88.7% | 11.43 |
| 17 Oct 2026 | 88.8% | 11.45 |