How many hydro power plants are in ISO-NE?

ISO-NE has 179 operating utility-scale hydro power plants with 3.8 GW of capacity, according to the EIA's monthly survey of power plants.

What is the largest hydro power plant in ISO-NE?

Northfield Mountain in Franklin County, Massachusetts is the largest, at 1,168 MW. It came online in 1973.

How many hydro power plants were built in ISO-NE in 2025?

0 hydro power plants came online in ISO-NE in 2025, with 0 MW of capacity.

Who is developing hydro power plants in ISO-NE?

Interconnection queues list each project under a project company, not the developer behind it. Cleanview researches the developer of every project and has them on paid plans.

Hydro power plants in ISO-NE

ISO-NE has 179 operating hydro power plants with 3.8 GW of capacity.

Operating179

Updated monthly. Last updated November 2026.

Under 50 MW50–249 MW250 MW and up

Updated monthly. Last updated November 2026.

ISO-NE had 178 hydro power plants online in 2016 and 179 in 2026

178

179

2016’162017’172018’182019’192020’202021’212022’222023’232024’242025’252026’26

Hydro power plants online at the end of each year. Source: EIA-860M, compiled by Cleanview.

The 10 largest hydro power plants in ISO-NE

Operating, by capacity

#	Hydro power plant	Location	Year online	Capacity
1	Northfield Mountain	Franklin County, Massachusetts	1973	1,168 MW
2	Bear Swamp	Berkshire County, Massachusetts	1974	666 MW
3	S C Moore	Grafton County, New Hampshire	2023	195 MW
4	Comerford	Grafton County, New Hampshire	1930	168 MW
5	Great Lakes Hydro America - ME	Penobscot County, Maine	1988	138 MW
6	Harris Hydro	Somerset County, Maine	1955	76 MW
7	Wyman Hydro	Somerset County, Maine	1940	72 MW
8	Cabot	Franklin County, Massachusetts	1917	62 MW
9	Rumford Falls Hydro Facility	Oxford County, Maine	1954	45 MW
10	Bellows Falls	Windham County, Vermont	1928	41 MW

Hydro power plants that came online most recently in ISO-NE

Newest first

#	Hydro power plant	Location	Year online	Capacity
1	S C Moore	Grafton County, New Hampshire	2023	195 MW
2	Ball Mountain Hydro	Windham County, Vermont	2016	2 MW
3	Glendale Hydroelectric Project	Berkshire County, Massachusetts	2014	1 MW
4	Orono B	Penobscot County, Maine	2013	4 MW
5	Stillwater B	Penobscot County, Maine	2013	2 MW
6	Highgate Falls	Franklin County, Vermont	2012	12 MW
7	Milford Hydro Station	Penobscot County, Maine	2011	8 MW
8	Orono Hydro Station	Penobscot County, Maine	2009	3 MW
9	Vernon Dam	Windham County, Vermont	2008	36 MW
10	Anson Abenaki Hydros	Somerset County, Maine	2008	29 MW

The developer behind each project is on paid plans. See plans

How Cleanview tracks hydro power plants

Operating hydro power plants come from the EIA's monthly survey of power plants. Planned projects come from the grid operators' interconnection queues. We research who is developing each one, since a queue lists a project company, not its owner.

Questions about hydro power plants in ISO-NE

How many hydro power plants are in ISO-NE?: ISO-NE has 179 operating utility-scale hydro power plants with 3.8 GW of capacity, according to the EIA's monthly survey of power plants.
What is the largest hydro power plant in ISO-NE?: Northfield Mountain in Franklin County, Massachusetts is the largest, at 1,168 MW. It came online in 1973.
How many hydro power plants were built in ISO-NE in 2025?: 0 hydro power plants came online in ISO-NE in 2025, with 0 MW of capacity.
Who is developing hydro power plants in ISO-NE?: Interconnection queues list each project under a project company, not the developer behind it. Cleanview researches the developer of every project and has them on paid plans.