Oahe

Oahe — 786 MW hydro plant, Hughes County, SD · Ask the Grid

Generation and physical site

EIA plant 3356 · Inventory for Aug 2026.

Reported operating nameplate by technology

Hydroelectric: 786.1 MW

Operating generators only. Battery power is in MW; stored energy is in MWh. These ratings do not establish a shared export limit.

Generator records (7)

EIA generator status and nameplate capacity for Oahe
Generator	Technology	Status	Power (MW)	Energy (MWh)
1	Conventional Hydroelectric	Operating	112.3	Unknown
2	Conventional Hydroelectric	Operating	112.3	Unknown
3	Conventional Hydroelectric	Operating	112.3	Unknown
4	Conventional Hydroelectric	Operating	112.3	Unknown
5	Conventional Hydroelectric	Operating	112.3	Unknown
6	Conventional Hydroelectric	Operating	112.3	Unknown
7	Conventional Hydroelectric	Operating	112.3	Unknown

Physical map location · OpenStreetMap: 44.45034, -100.38745
Filed location · EIA: 44.45040, -100.38660

Sources and observation dates

Inventory source: EIA-860M workbook (preliminary)
EIA reporting month: Aug 2026
EIA retrieved: Oct 10, 2026
OSM extract: Oct 9, 2026
OSM last mapped edit: May 13, 2022
Map prepared: Oct 10, 2026
Field verification: Not reported

Reporting month describes the inventory. Retrieval and map preparation describe processing; an OSM edit does not establish an in-service date.

EIA source inventory

Units and generators

Operating generator records and technology attributes reported through EIA-860.

Generator	Capacity	Technology	Operation	Status
1	112.3 MW 102 MW summer	Conventional Hydroelectric Water · HY	Apr 1962	Operating
2	112.3 MW 102 MW summer	Conventional Hydroelectric Water · HY	Dec 1962	Operating
3	112.3 MW 102 MW summer	Conventional Hydroelectric Water · HY	Jul 1962	Operating
4	112.3 MW 102 MW summer	Conventional Hydroelectric Water · HY	Oct 1962	Operating
5	112.3 MW 102 MW summer	Conventional Hydroelectric Water · HY	Mar 1963	Operating
6	112.3 MW 102 MW summer	Conventional Hydroelectric Water · HY	May 1963	Operating
7	112.3 MW 102 MW summer	Conventional Hydroelectric Water · HY	Jun 1963	Operating

Commercial, land, and environmental record

Source-backed project transactions, agreements, land records, permits, and environmental disclosures. Portfolio and adjacent-project facts remain explicitly scoped.

Transactions and agreements

Construction Start

Aug 1948

Construction of Oahe began in August 1948; initial construction contract awarded for west access highway; first of eight earthwork contracts for dam embankment let in May 1950.

U.S. Army Corps of Engineers

water.usace.army.mil

Dam Closure And River Diversion

Aug 3, 1958

Missouri River diverted through outlet works; dam closure accomplished 1958, embankment completion 1961.

U.S. Army Corps of Engineers

nwo.usace.army.mil

Reservoir Filling Start

Aug 1958

Reservoir filling of Lake Oahe initiated.

U.S. Army Corps of Engineers

nwo.usace.army.mil

Reservoir Operational Milestone

Apr 3, 1962

Reservoir first reached minimum operating pool level.

U.S. Army Corps of Engineers

nwo.usace.army.mil

Initial Commercial Operation (First Unit)

Apr 1962

First of seven generators entered commercial operation (April per project statistics; March per hydropower narrative). Generator entered operation producing 85,000 kW initially.

U.S. Army Corps of Engineers

nwo.usace.army.mil

Related parties and identifiers

Parties, market resources, and identifiers tied to this asset, with owner, operator, developer, EPC, compliance provider, and interconnecting entity roles kept separate.

Parties and identifiers

OrganizationRoleBasis

Reporting portfolio

EIA reporting entity

USACE-Omaha

Entity 19635

Operating portfolio

6 plants

4 states

Reported capacity

2,482.5 MW

Conventional Hydroelectric

Largest reported plants in this portfolio
Largest reported plants	Capacity	State
OaheCurrent	786.1 MW	SD
Garrison	583.4 MW	ND
Big Bend Dam	538.3 MW	SD
Fort Randall	280 MW	SD
Fort Peck	162.4 MW	MT
Gavins Point	132.3 MW	NE

Portfolio membership follows the latest EIA-860 reporting entity. It does not imply ultimate ownership.

View full reporting portfolio

Timeline and sources

Project milestones and public references behind the asset profile.

Project timeline

Aug 1948
Aug 1948
Construction of Oahe beginswater.usace...
Construction of Oahe began in August 1948; initial construction contract awarded for west access highway; first of eight earthwork contracts for dam embankment let in May 1950.
Aug 1958
Aug 1958
Reservoir Filling Initiatednwo.usace.a...
Reservoir filling of Lake Oahe initiated.
Aug 3, 1958
Aug 3, 1958
Oahe Dam Closurenwo.usace.a...
Missouri River diverted through outlet works; dam closure accomplished 1958, embankment completion 1961.
View 9 more milestonesHide 9 milestones
1. Apr 1962
  Apr 1962
  First Oahe generator enters servicenwo.usace.a...
  First of seven generators entered commercial operation (April per project statistics; March per hydropower narrative). Generator entered operation producing 85,000 kW initially.
2. Apr 3, 1962
1964
1964
Oahe Project Completionnwo.usace.a...
Oahe project completed in 1964 ahead of schedule and under budget. Total project cost $340 million.
1980
1980
Oahe Generator Upgradenwo.usace.a...
Generators upgraded in the 1980s. Per-unit capability increased from original 85,000 kW to approximately 112,290 kW each. Exact upgrade date not specified; year range given.
2017
2017
Reivax excitation system contract awardedreivax.com
Reivax North America awarded contract to supply and install replacement static excitation systems for all seven Oahe generators. Project completed ahead of schedule in 2017.

Sources

PublisherReferenceType

U.S. Energy Information AdministrationEIA-860 generator inventoryFederal registry

U.S. Energy Information AdministrationEIA-923 generation filingsFederal filing

interxdata.cominterxdata.compublic_source

Common questions about Oahe

Answered from the published record above. Questions whose inputs this profile does not carry are omitted rather than estimated.

How big is Oahe?

Oahe reports 786.1 MW hydroelectric of operating nameplate capacity. These technology ratings do not establish a common export limit. Source: EIA Aug 2026.

What kind of plant is Oahe?

Oahe is a Conventional Hydroelectric facility in Hughes County, SD, participating in the SPP market.

Where is Oahe located?

Oahe is in Hughes County, SD, inside the SPP balancing area.

Who operates Oahe?

Oahe is operated by USACE-Omaha according to the EIA generator inventory. Reporting membership does not by itself establish ultimate ownership.

How much electricity does Oahe generate?

Oahe reported 2,188.8 GWh over the twelve months to 2024-12. Figures are net generation as filed to EIA-923.

How does Oahe compare to other plants?

By capacity, Oahe ranks #17 of 1,356 operating plants of the same technology nationally. It ranks #1 of 4 in SD.

Co-located assets

Plants within 25 km, nearest first, regardless of technology. Proximity is straight-line distance between mapped plant coordinates; it does not by itself establish a shared point of interconnection.

Ft. PierrePetroleum LiquidsPetroleum Liquids6 MW9.2 km

Overview

Infrastructure record

Oahe

Overview

Infrastructure record

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Structured profile

Generation and physical site

Reported operating nameplate by technology

Related assets

Big Bend Dam

Garrison

Fort Randall

Yellowtail

Gavins Point

Salina

Units and generators

Performance

Peer context

Monthly generation

Grid and market context

Nearby substations

Commercial, land, and environmental record

Transactions and agreements

Related parties and identifiers

Parties and identifiers

Reporting portfolio

Timeline and sources

Project timeline

Sources

Common questions about Oahe

How big is Oahe?

What kind of plant is Oahe?

Where is Oahe located?

Who operates Oahe?

How much electricity does Oahe generate?

How does Oahe compare to other plants?

Co-located assets