Storage from official US gauges (USGS, USACE, Bureau of Reclamation, CDEC). Fill % uses design capacity from the National Inventory of Dams where available; a few sites without a match fall back to the 5-year maximum.

About reservoirs in South Dakota

As of September 13, 2026, the reservoirs we track across South Dakota that report live levels hold roughly 25,191 hm³ of water — about 78.0% of their combined capacity. Taken together, South Dakota's reservoirs are within their normal operating range.

Across the region, 2 are low. Big Bend Dam & Reservoir is the fullest at 97.5%, while Belle Fourche Reservoir is the lowest at 28.1%.

Over the most recent week on record, 1 reservoir rose and 3 reservoirs fell across South Dakota.

Storage figures for South Dakota come from USGS · USACE · BOR · CDEC; the most recent reading is from September 13, 2026. Each reservoir below links to its own page with full history and seasonal context.

South Dakota at a glance

Reservoirs tracked: 14
Average fill: 78.0%
Water stored: 25,191 hm³
Combined capacity: 32,291 hm³
Fullest: Big Bend Dam & Reservoir (97.5%)
Lowest: Belle Fourche Reservoir (28.1%)
Last updated: September 13, 2026

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