Northfield Mountain
Northfield Mountain is a 1 GW pumped storage hydro plant in Franklin County, Massachusetts, operated by FirstLight Power Resources, Inc. - MA. EIA-860M lists 4 generating units here, inside ISO New England. Its units entered service between 1972 and 1973.
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
- 1,168 MW
- 1,168 MW net summer
- Generating units
- 4
- In service
- 1972–1973
- EIA plant ID
- 547
Where it is
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- County
- Franklin County, Massachusetts
- Coordinates
- 42.6107, -72.4716
- Balancing authority
- ISNE
- Sector
- IPP Non-CHP
Units, technology and status
- Operator of record
- FirstLight Power Resources, Inc. - MA
- Primary energy source
- Pumped storage
- Technologies
- Hydroelectric Pumped Storage
- Status
- Operating
Every plant FirstLight Power Resources, Inc. - MA reports to EIA →
Northfield Mountain: FAQ
- Where is Northfield Mountain?
- In Franklin 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 Northfield Mountain?
- 1 GW of nameplate capacity across 4 units, as of the EIA-860M release for 2026-07.
- Who owns Northfield Mountain?
- EIA-860M names FirstLight Power Resources, Inc. - MA 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 Northfield Mountain LLC?
- Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — FirstLight Power Resources, Inc. - MA 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 "Northfield Mountain LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.
- Is Northfield Mountain still running?
- EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.