Oahe Dam · Missouri River · SD–ND
Lake Oahe
231 miles of the Missouri behind one dam, and the pool the Dakota Access pipeline crosses under.
Water surface elevation
1,593.6 ft
US Army Corps, hourly · Sep 2, 7:00 AM CDT
Water in storage
14.89 million acre-feet
US Army Corps, hourly · Sep 1, 12:00 AM CDT
Share of conservation capacity
79.8% full
against the retrieved 2026-08-31 conservation capacity figure (USACE CWMS location level NWDM/OAHE.Stor.Inst.0.Top of Conservation)
Below full pool
26.4 ft
full pool at 1,620.0 ft
This month in the record
lower than 81% of the 59 Septembers on record
monthly mean storage; record low 9.98 million acre-feet (2006), record high 22.04 million acre-feet (1997)
30-day trend
-16,867 af/day
storage, 2026-08-01 → 2026-08-31; over the year -3,816 af/day. Measured change, not a forecast.
Drought at the dam
none this week
US Drought Monitor at the dam's coordinates, released 2026-08-27; the feeding basin can differ.
Flood space left
8.09 million acre-feet
room above today's storage up to the Corps' flood-control ceiling, same total-volume basis
79.8% full
of conservation capacity, by storage (retrieved 2026-08-31 figure, USACE CWMS location level NWDM/OAHE.Stor.Inst.0.Top of Conservation). Sedimentation slowly shrinks real capacity.
The water line is elevation (USACE project datum); the percentage is storage ÷ capacity. They are different measures — a reservoir's volume is not linear in its depth, so the line's height in this column is not the percentage.
The last 120 days
Daily water-surface elevation in feet. The axis hugs the data — it does not start at zero. Source: committed snapshot (USACE CWMS, retrieved 2026-08-31).
See the numbers as a table
| Date | Elevation (ft) |
|---|---|
| Aug 31 | 1594.01 |
| Aug 30 | 1594.08 |
| Aug 29 | 1594.02 |
| Aug 28 | 1594.06 |
| Aug 27 | 1594.23 |
| Aug 26 | 1594.37 |
| Aug 25 | 1594.53 |
| Aug 24 | 1594.46 |
| Aug 23 | 1594.38 |
| Aug 22 | 1594.50 |
| Aug 21 | 1594.71 |
| Aug 20 | 1594.85 |
| Aug 19 | 1594.80 |
| Aug 18 | 1594.96 |
| Aug 17 | 1595.01 |
| Aug 16 | 1595.04 |
| Aug 15 | 1595.31 |
| Aug 14 | 1595.15 |
| Aug 13 | 1595.46 |
| Aug 12 | 1595.36 |
| Aug 11 | 1595.45 |
| Aug 10 | 1595.46 |
| Aug 9 | 1595.58 |
| Aug 8 | 1595.55 |
| Aug 7 | 1595.64 |
| Aug 6 | 1595.90 |
| Aug 5 | 1595.93 |
| Aug 4 | 1596.14 |
| Aug 3 | 1596.48 |
| Aug 2 | 1596.07 |
Most recent 30 days shown.
Storage against capacity
Monthly mean storage in acre-feet, zero baseline. The dashed line is the retrieved 2026-08-31 conservation capacity figure (USACE CWMS location level NWDM/OAHE.Stor.Inst.0.Top of Conservation) — sedimentation slowly shrinks real capacity. Storage can legitimately rise past a conservation-pool line when the flood pool is in use.
See the numbers as a table
| Month | Mean storage (acre-feet) | Days gaged |
|---|---|---|
| Aug 2026 | 15,174,226 | 31 |
| Jul 2026 | 15,694,161 | 31 |
| Jun 2026 | 15,985,462 | 26 |
| May 2026 | 16,243,323 | 31 |
| Apr 2026 | 16,679,433 | 30 |
| Mar 2026 | 17,023,903 | 31 |
| Feb 2026 | 16,885,071 | 28 |
| Jan 2026 | 16,773,290 | 31 |
| Dec 2025 | 16,524,290 | 31 |
| Nov 2025 | 16,530,200 | 30 |
| Oct 2025 | 16,576,000 | 31 |
| Sep 2025 | 16,417,433 | 30 |
| Aug 2025 | 16,302,452 | 31 |
| Jul 2025 | 16,186,129 | 31 |
| Jun 2025 | 16,127,967 | 30 |
| May 2025 | 15,862,355 | 31 |
| Apr 2025 | 15,898,167 | 30 |
| Mar 2025 | 16,214,645 | 31 |
| Feb 2025 | 15,909,821 | 28 |
| Jan 2025 | 15,631,645 | 31 |
| Dec 2024 | 15,480,129 | 31 |
| Nov 2024 | 15,645,800 | 30 |
| Oct 2024 | 16,408,032 | 31 |
| Sep 2024 | 17,314,600 | 30 |
Most recent 24 months shown.
Where these numbers come from
Readings at Lake Oahe are the measuring agencies' own: each value above names its source (USGS gage, Bureau of Reclamation daily record, Army Corps project data, or this desk's committed copy) and its observation time in the reservoir's own time zone. The conservation capacity figure is the retrieved 2026-08-31 USACE CWMS location level NWDM/OAHE.Stor.Inst.0.Top of Conservation number — its basis: top of conservation pool (Corps location level, total-volume basis); sedimentation slowly shrinks real capacity, so the vintage travels with the percent.