Reservoir · Montana · United States · USACE CWMS
Yellowtail Dam & Reservoir
82.4% full
Capacity
1,258.86 hm³
Volume stored
1037 hm³
Coordinates
45.307°N, 107.958°W
Last updated
2026-07-29
Current fill
82.4%vs 7 days ago
+0.1%gaining
vs 1 year ago
+1.7%year-over-year
7-day trend
→stable
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: 2026-07-29.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 45.307, -107.958 · Open in Google Maps
About Yellowtail Dam & Reservoir
As of July 29, 2026, Yellowtail Dam & Reservoir is filled to 82.4% of its total capacity, holding roughly 1,037 hm³ of water out of a maximum 1,259 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 1.7 points above its level on the same date a year earlier.
Across the readings we hold for Yellowtail Dam & Reservoir — 1821 data points between July 31, 2021 and July 29, 2026 — the level has ranged from a low of 75.7% (May 9, 2024) to a high of 105.0% (June 25, 2023). On average the reservoir is fullest around July and at its lowest around April.
It is operated by USACE primarily for multiple purposes. It lies within the Montana basin at 45.307°N, 107.958°W.
Key facts
- Current fill level
- 82.4%
- Water stored
- 1,037 hm³
- Total capacity
- 1,259 hm³
- 7-day change
- ▲ 0.1 pts
- Year-on-year
- ▲ 1.7 pts
- Primary use
- Multipurpose
- River basin
- Montana
- Operator
- USACE
- Coordinates
- 45.307°N, 107.958°W
- Last updated
- July 29, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 29 Jul 2026 | 82.4% | 1,037 |
| 28 Jul 2026 | 82.3% | 1,037 |
| 27 Jul 2026 | 82.3% | 1,036 |
| 26 Jul 2026 | 82.3% | 1,036 |
| 25 Jul 2026 | 82.3% | 1,037 |
| 24 Jul 2026 | 82.4% | 1,037 |
| 23 Jul 2026 | 82.4% | 1,038 |
| 22 Jul 2026 | 82.4% | 1,038 |
| 21 Jul 2026 | 82.4% | 1,038 |
| 20 Jul 2026 | 82.5% | 1,038 |
| 19 Jul 2026 | 82.5% | 1,038 |
| 18 Jul 2026 | 82.4% | 1,037 |
Frequently asked questions
What is the current water level of Yellowtail Dam & Reservoir?
As of July 29, 2026, Yellowtail Dam & Reservoir is at 82.4% of its capacity, holding approximately 1,037 hm³ of water, according to USACE CWMS (US Army Corps of Engineers) data.
Is Yellowtail Dam & Reservoir reservoir full?
No. As of July 29, 2026, Yellowtail Dam & Reservoir is high at 82.4% of its capacity, so it is not full.
Is the water level at Yellowtail Dam & Reservoir rising or falling?
The level at Yellowtail Dam & Reservoir has been broadly stable over the latest week on record (+0.1 points).
How much water can Yellowtail Dam & Reservoir hold?
Yellowtail Dam & Reservoir has a total capacity of 1,259 hm³.
Where is Yellowtail Dam & Reservoir reservoir located?
Yellowtail Dam & Reservoir is located in Montana, United States, within the Montana basin (coordinates 45.307°N, 107.958°W).
What is Yellowtail Dam & Reservoir used for?
Yellowtail Dam & Reservoir is used primarily for multiple purposes, and is managed by USACE.