Bear Swamp
Bear Swamp is a 666 MW pumped storage hydro plant in Berkshire County, Massachusetts, operated by Bear Swamp Power Company LLC. EIA-860M lists 2 generating units here, inside ISO New England. Its units entered service in 1974.
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
- 666 MW
- 666 MW net summer
- Generating units
- 2
- In service
- 1974
- EIA plant ID
- 8005
Where it is
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- County
- Berkshire County, Massachusetts
- Coordinates
- 42.6839, -72.9599
- Balancing authority
- ISNE
- Sector
- IPP Non-CHP
Units, technology and status
- Operator of record
- Bear Swamp Power Company LLC
- Primary energy source
- Pumped storage
- Technologies
- Hydroelectric Pumped Storage
- Status
- Operating
Bear Swamp: FAQ
- Where is Bear Swamp?
- In Berkshire County, Massachusetts (MA). 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 Bear Swamp?
- 666 MW of nameplate capacity across 2 units, as of the EIA-860M release for 2026-07.
- Who owns Bear Swamp?
- EIA-860M names Bear Swamp Power Company LLC 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 Bear Swamp LLC?
- Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — Bear Swamp Power Company LLC 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 "Bear Swamp LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.
- Is Bear Swamp still running?
- EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.