Reservoir · South Dakota · United States · USACE CWMS
Oahe Dam & Reservoir
75.8% full
Capacity
23,806.2 hm³
Volume stored
18041 hm³
Coordinates
44.450°N, 100.405°W
Last updated
2026-09-10
Current fill
75.8%vs 7 days ago
-0.6%losing
vs 1 year ago
-8.6%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: 2026-09-10.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 44.450, -100.405 · Open in Google Maps
About Oahe Dam & Reservoir
As of September 10, 2026, Oahe Dam & Reservoir is filled to 75.8% of its total capacity, holding roughly 18,041 hm³ of water out of a maximum 23,806 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 (-0.6 pts), and it is 8.6 points below its level on the same date a year earlier.
Across the readings we hold for Oahe Dam & Reservoir — 1821 data points between September 12, 2021 and September 10, 2026 — the level has ranged from a low of 70.6% (December 8, 2022) to a high of 93.5% (July 31, 2024). On average the reservoir is fullest around July and at its lowest around December.
It is operated by USACE primarily for multiple purposes. It lies within the South Dakota basin at 44.450°N, 100.405°W.
Key facts
- Current fill level
- 75.8%
- Water stored
- 18,041 hm³
- Total capacity
- 23,806 hm³
- 7-day change
- ▼ 0.6 pts
- Year-on-year
- ▼ 8.6 pts
- Primary use
- Multipurpose
- River basin
- South Dakota
- Operator
- USACE
- Coordinates
- 44.450°N, 100.405°W
- Last updated
- September 10, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 10 Sep 2026 | 75.8% | 18,041 |
| 9 Sep 2026 | 75.9% | 18,071 |
| 8 Sep 2026 | 76.0% | 18,100 |
| 7 Sep 2026 | 76.1% | 18,110 |
| 6 Sep 2026 | 76.1% | 18,126 |
| 5 Sep 2026 | 76.2% | 18,146 |
| 4 Sep 2026 | 76.3% | 18,170 |
| 3 Sep 2026 | 76.4% | 18,196 |
| 2 Sep 2026 | 76.5% | 18,222 |
| 1 Sep 2026 | 77.2% | 18,368 |
| 31 Aug 2026 | 77.2% | 18,389 |
| 30 Aug 2026 | 77.3% | 18,397 |