Reservoir · South Dakota · United States · USACE CWMS
Big Bend Dam & Reservoir
97.0% full
Capacity
2,127.76 hm³
Volume stored
2064 hm³
Coordinates
44.041°N, 99.445°W
Last updated
2026-09-10
Current fill
97.0%vs 7 days ago
+0.9%gaining
vs 1 year ago
-0.1%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. 44.041, -99.445 · Open in Google Maps
About Big Bend Dam & Reservoir
As of September 10, 2026, Big Bend Dam & Reservoir is filled to 97.0% of its total capacity, holding roughly 2,064 hm³ of water out of a maximum 2,128 hm³. At this level the reservoir is high.
Over the most recent week on record the fill level has held broadly steady (+0.9 pts), and it sits close to where it was a year earlier.
Across the readings we hold for Big Bend Dam & Reservoir — 1821 data points between September 12, 2021 and September 10, 2026 — the level has ranged from a low of 94.9% (July 2, 2022) to a high of 99.2% (April 29, 2024). On average the reservoir is fullest around June and at its lowest around July.
It is operated by USACE primarily for multiple purposes. It lies within the South Dakota basin at 44.041°N, 99.445°W.
Key facts
- Current fill level
- 97.0%
- Water stored
- 2,064 hm³
- Total capacity
- 2,128 hm³
- 7-day change
- ▲ 0.9 pts
- Year-on-year
- ▼ 0.1 pts
- Primary use
- Multipurpose
- River basin
- South Dakota
- Operator
- USACE
- Coordinates
- 44.041°N, 99.445°W
- Last updated
- September 10, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 10 Sep 2026 | 97.0% | 2,064 |
| 9 Sep 2026 | 97.3% | 2,070 |
| 8 Sep 2026 | 97.6% | 2,076 |
| 7 Sep 2026 | 97.6% | 2,077 |
| 6 Sep 2026 | 96.5% | 2,054 |
| 5 Sep 2026 | 95.6% | 2,034 |
| 4 Sep 2026 | 95.9% | 2,040 |
| 3 Sep 2026 | 96.1% | 2,045 |
| 2 Sep 2026 | 96.5% | 2,054 |
| 1 Sep 2026 | 97.0% | 2,065 |
| 31 Aug 2026 | 98.1% | 2,088 |
| 30 Aug 2026 | 96.6% | 2,055 |