Reservoir · Montana · United States · USACE CWMS
Helena Valley Reservoir, MT
87.3% full
Capacity
12.89 hm³
Volume stored
11 hm³
Coordinates
46.638°N, 111.882°W
Last updated
2026-06-30
Current fill
87.3%vs 7 days ago
+1.7%gaining
vs 1 year ago
-7.5%year-over-year
7-day trend
↑rising
Data source: USACE CWMS — US Army Corps of Engineers — 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: 2026-06-30.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 46.638, -111.882 · Open in Google Maps
About Helena Valley Reservoir, MT
As of June 30, 2026, Helena Valley Reservoir, MT is filled to 87.3% of its total capacity, holding roughly 11 hm³ of water out of a maximum 13 hm³. At this level the reservoir is high.
Over the most recent week on record the fill level has risen by 1.7 percentage points, and it is 7.5 points below its level on the same date a year earlier.
Across the readings we hold for Helena Valley Reservoir, MT — 1815 data points between July 2, 2021 and June 30, 2026 — the level has ranged from a low of 60.6% (April 16, 2025) to a high of 99.7% (July 3, 2023). On average the reservoir is fullest around May and at its lowest around March.
It is operated by USACE primarily for multiple purposes. It lies within the Montana basin at 46.638°N, 111.882°W.
Key facts
- Current fill level
- 87.3%
- Water stored
- 11 hm³
- Total capacity
- 13 hm³
- 7-day change
- ▲ 1.7 pts
- Year-on-year
- ▼ 7.5 pts
- Primary use
- Multipurpose
- River basin
- Montana
- Operator
- USACE
- Coordinates
- 46.638°N, 111.882°W
- Last updated
- June 30, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 30 Jun 2026 | 87.3% | 11 |
| 29 Jun 2026 | 85.6% | 11 |
| 28 Jun 2026 | 84.9% | 11 |
| 27 Jun 2026 | 84.9% | 11 |
| 26 Jun 2026 | 84.9% | 11 |
| 25 Jun 2026 | 85.1% | 11 |
| 24 Jun 2026 | 85.4% | 11 |
| 23 Jun 2026 | 85.8% | 11 |
| 22 Jun 2026 | 86.1% | 11 |
| 21 Jun 2026 | 86.7% | 11 |
| 20 Jun 2026 | 87.5% | 11 |
| 19 Jun 2026 | 88.3% | 11 |
Frequently asked questions
What is the current water level of Helena Valley Reservoir, MT?
As of June 30, 2026, Helena Valley Reservoir, MT is at 87.3% of its capacity, holding approximately 11 hm³ of water, according to USACE CWMS (US Army Corps of Engineers) data.
Is Helena Valley Reservoir, MT reservoir full?
No. As of June 30, 2026, Helena Valley Reservoir, MT is high at 87.3% of its capacity, so it is not full.
Is the water level at Helena Valley Reservoir, MT rising or falling?
The level at Helena Valley Reservoir, MT is rising — it gained 1.7 percentage points over the latest week on record.
How much water can Helena Valley Reservoir, MT hold?
Helena Valley Reservoir, MT has a total capacity of 13 hm³.
Where is Helena Valley Reservoir, MT reservoir located?
Helena Valley Reservoir, MT is located in Montana, United States, within the Montana basin (coordinates 46.638°N, 111.882°W).
What is Helena Valley Reservoir, MT used for?
Helena Valley Reservoir, MT is used primarily for multiple purposes, and is managed by USACE.