Where is Cobble Mountain?

In Hampden 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 Cobble Mountain?

33 MW of nameplate capacity across 3 units, as of the EIA-860M release for 2026-07.

Who owns Cobble Mountain?

EIA-860M names City of Holyoke Gas and Elec Dept - (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 Cobble Mountain LLC?

Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — City of Holyoke Gas and Elec Dept - (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 "Cobble Mountain LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.

Is Cobble Mountain still running?

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

Cobble Mountain

Cobble Mountain is a 33 MW hydroelectric power plant in Hampden County, Massachusetts, operated by City of Holyoke Gas and Elec Dept - (MA). EIA-860M lists 3 generating units here, inside ISO New England. Its units entered service in 1930.

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: 33 MW; 32.6 MW net summer
Generating units: 3
In service: 1930
EIA plant ID: 1630

Where it is

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County: Hampden County, Massachusetts
Coordinates: 42.1171, -72.8647
Balancing authority: ISNE
Sector: Electric Utility

Units, technology and status

Operator of record: City of Holyoke Gas and Elec Dept - (MA)
Primary energy source: Hydro
Technologies: Conventional Hydroelectric
Status: Operating

Every plant City of Holyoke Gas and Elec Dept - (MA) reports to EIA →

Cobble Mountain: FAQ

Where is Cobble Mountain?: In Hampden 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 Cobble Mountain?: 33 MW of nameplate capacity across 3 units, as of the EIA-860M release for 2026-07.
Who owns Cobble Mountain?: EIA-860M names City of Holyoke Gas and Elec Dept - (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 Cobble Mountain LLC?: Probably, but EIA-860M does not say. The survey records a plant name and a reporting entity — City of Holyoke Gas and Elec Dept - (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 "Cobble Mountain LLC" usually means this site. This page shows only what EIA files, and does not assert a corporate structure it cannot see.
Is Cobble Mountain still running?: EIA-860M files it as "Operating" for 2026-07. Statuses change monthly, and this page follows the monthly release.