Northfield Mountain — 1,168 MW hydro plant, MA

Northfield Mountain — 1,168 MW hydro plant, MA · Ask the Grid

Generation and physical site

EIA plant 547 · Inventory for Aug 2026.

Reported operating nameplate by technology

Hydroelectric: 1,168 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 (4)

EIA generator status and nameplate capacity for Northfield Mountain
Generator	Technology	Status	Power (MW)	Energy (MWh)
1	Hydroelectric Pumped Storage	Operating	292	Unknown
2	Hydroelectric Pumped Storage	Operating	292	Unknown
3	Hydroelectric Pumped Storage	Operating	292	Unknown
4	Hydroelectric Pumped Storage	Operating	292	Unknown

Physical map location · OpenStreetMap: 42.61306, -72.45784
Filed location · EIA: 42.61068, -72.47164

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	292 MW 292 MW summer	Hydroelectric Pumped Storage Water · PS	Feb 1973	Operating
2	292 MW 292 MW summer	Hydroelectric Pumped Storage Water · PS	Oct 1973	Operating
3	292 MW 292 MW summer	Hydroelectric Pumped Storage Water · PS	Jul 1973	Operating
4	292 MW 292 MW summer	Hydroelectric Pumped Storage Water · PS	Nov 1972	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

License Issued

May 14, 1968

FERC issued the original license for the Northfield Mountain Project (Project No. 2485).

Federal Energy Regulatory Commission · Project applicant

northfield-relicensing.com

Modernization Began

Sep 15, 2011

Units 2, 3, and 4 began efficiency improvements with turbine-runner replacement and motor-generator rewinds, continuing through 2014.

FirstLight

northfield-relicensing.com

Modernization Completed

2014

Modernization of Units 2, 3, and 4 completed (turbine-runner replacement and motor-generator rewinds). Station capacity increased from 1,080 MW (270 MW/unit historical) to 1,166.8 MW (291.7 MW/unit).

FirstLight

northfield-relicensing.com

Major Maintenance

Aug 2015

Unit 1 motor-generator rewind scheduled to begin (continuing through February 2016).

FirstLight

northfield-relicensing.com

License Expired

Apr 30, 2018

Original FERC license for Northfield Mountain (Project 2485) expired. Facility continued operating under annual licenses pursuant to Section 15 of the Federal Power Act during relicensing proceedings.

Federal Energy Regulatory Commission

northfield-relicensing.com

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.

Relationship graph

Drag organizations to explore the network. Select a node to pin its details and available page link.

AssetOwner / operator

Parties and identifiers

OrganizationRoleBasis

Northfield Mountain LLCOwnerowner and FERC licensee

Public Sector Pension Investment Board (PSP Investments)Owner / investorowner of FirstLight USA and ultimate parent

Hull Street Energy, LLCAcquirerprospective owner pending regulatory approval (announced May 19, 2026)

Energy Capital PartnersFormer ownerportfolio owner 2006–2008

Northeast Utilities / Northeast Generation CompanyFormer owneroriginal portfolio owner and 2006 seller

GDF SUEZ / ENGIE GroupFormer ownerportfolio owner 2008–2016

Reporting portfolio

EIA reporting entity

FirstLight Power Resources, Inc. - MA

Entity 58185

Operating portfolio

4 plants

1 states

Reported capacity

1,237.4 MW

Conventional Hydroelectric · Hydroelectric Pumped Storage · Solar Photovoltaic

Largest reported plants in this portfolio
Largest reported plants	Capacity	State
Northfield MountainCurrent	1,168 MW	MA
Cabot	61.8 MW	MA
Turners Falls	5.7 MW	MA
NFM Solar Power LLC	1.9 MW	MA

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

May 14, 1968
May 14, 1968
Original FERC License Issuednorthfield-...
FERC issued the original license for the Northfield Mountain Project (Project No. 2485).
Nov 1972
Nov 1972
Generator enters operationEIA-860
EIA-860 lists generator 4 with this operating date.
Feb 1973
Feb 1973
Generator enters operationEIA-860
EIA-860 lists generator 1 with this operating date.
View 9 more milestonesHide 9 milestones
1. Jul 1973
  Jul 1973
  Generator enters operationEIA-860
  EIA-860 lists generator 3 with this operating date.
2. Oct 1973
  Oct 1973
Dec 4, 2020
Dec 4, 2020
Amended Final License Application Filedfrcog.org
Northfield Mountain LLC and FirstLight MA Hydro LLC filed amended final license applications for the Northfield Mountain and Turners Falls projects.
Feb 2022
Feb 2022
Relicensing Agreement in Principlenorthfield-...
FirstLight and stakeholders entered into an Agreement in Principle covering relicensing measures for Northfield Mountain and Turners Falls projects, which had been operating on annual licenses since April 30, 2018.
Mar 31, 2023
Mar 31, 2023
Environmental and Fish-Passage Settlement Agreement Filedfirstlight....
FirstLight filed a Flows and Fish Passage Settlement Agreement with FERC for Northfield Mountain and Turners Falls projects, committing to over $350 million in combined environmental and operational measures, including approximately $152 million for state-of-the-art fish-passage facilities.

Sources

PublisherReferenceType

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

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

firstlight.energyfirstlight.energypublic_source

Common questions about Northfield Mountain

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

How big is Northfield Mountain?

Northfield Mountain reports 1,168 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 Northfield Mountain?

Northfield Mountain is a Hydroelectric Pumped Storage facility in Franklin County, MA, participating in the ISO-NE market.

Where is Northfield Mountain located?

Northfield Mountain is in Franklin County, MA, inside the ISO-NE balancing area.

Who operates Northfield Mountain?

Northfield Mountain is operated by FirstLight Power Resources, Inc. - MA according to the EIA generator inventory. Reporting membership does not by itself establish ultimate ownership.

How much electricity does Northfield Mountain generate?

Northfield Mountain reported 955.3 GWh over the twelve months to 2026-07. For a storage plant this is reported gross generation — a discharge proxy, not a cycle count or a conventional capacity factor.

How does Northfield Mountain compare to other plants?

By capacity, Northfield Mountain ranks #6 of 39 operating plants of the same technology nationally. It ranks #1 of 2 in MA.

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.

NFM Solar Power LLCSolar PhotovoltaicSolar Photovoltaic2 MW1.4 km Erving CSGSolar PhotovoltaicSolar Photovoltaic1 MW1.5 km French King Solar LLCSolar PhotovoltaicSolar Photovoltaic5 MW3.3 km Erving Paper MillsNatural Gas Fired Combustion Turbine, Natural Gas Steam TurbineNatural Gas Fired Combustion Turbine, Natural Gas Steam Turbine

Overview

Infrastructure record

Overview

Infrastructure record

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Structured profile

Generation and physical site

Reported operating nameplate by technology

Related assets

Bear Swamp

Cabot

Vernon Dam

Turners Falls

Harriman

Hadley Falls

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

Relationship graph

Parties and identifiers

Reporting portfolio

Timeline and sources

Project timeline

Sources

Common questions about Northfield Mountain

How big is Northfield Mountain?

What kind of plant is Northfield Mountain?

Where is Northfield Mountain located?

Who operates Northfield Mountain?

How much electricity does Northfield Mountain generate?

How does Northfield Mountain compare to other plants?

Co-located assets

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