In Grant County, South Dakota (SD). The map on this page is placed at the coordinates EIA files for the plant, which locate the site rather than any individual unit.

How big is Big Stone?

451 MW of nameplate capacity across 2 units, as of the EIA-860M release for 2026-07.

EIA-860M names Otter Tail Power Co as the reporting entity. That is the operator of record on the survey, which is not always the ultimate owner.

Is this the same as Big Stone LLC?

Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — Otter Tail Power Co here — not the project company that holds the asset. Project companies are commonly registered as an LLC carrying the plant's name, so a search for "Big Stone LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.

Is Big Stone still running?

EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.

Big Stone

Big Stone is a 451 MW coal power plant in Grant County, South Dakota, operated by Otter Tail Power Co. EIA-860M lists 2 generating units here, inside MISO. Its units entered service in 1975.

As of 2026-07 (inventory dated 2026-07-31) · EIA-860M Preliminary Monthly Electric Generator Inventory · eia.gov/…/july_generator2026.xlsx · eia.gov/…/eia860m

Nameplate capacity: 451 MW; 478.7 MW net summer
Generating units: 2
In service: 1975
EIA plant ID: 6098

Where it is

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County: Grant County, South Dakota
Coordinates: 45.3037, -96.5101
Balancing authority: MISO
Sector: Electric Utility

Units, technology and status

Operator of record: Otter Tail Power Co
Primary energy source: Coal
Technologies: Conventional Steam Coal, Petroleum Liquids
Status: Operating (1) · Standby/Backup (1)

This site runs on more than one energy source. EIA-860M capacity splits: Coal 450 MW, Petroleum 1 MW. It is filed here under Coal, the source with the most capacity.

Every plant Otter Tail Power Co reports to EIA →

Big Stone: FAQ

Where is Big Stone?: In Grant County, South Dakota (SD). The map on this page is placed at the coordinates EIA files for the plant, which locate the site rather than any individual unit.
How big is Big Stone?: 451 MW of nameplate capacity across 2 units, as of the EIA-860M release for 2026-07.
Who owns Big Stone?: EIA-860M names Otter Tail Power Co as the reporting entity. That is the operator of record on the survey, which is not always the ultimate owner.
Is this the same as Big Stone LLC?: Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — Otter Tail Power Co here — not the project company that holds the asset. Project companies are commonly registered as an LLC carrying the plant's name, so a search for "Big Stone LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.
Is Big Stone still running?: EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.