Somersworth Lower Great Dam
Hydro power plant in Strafford County, New Hampshire. 1.3 MW of nameplate capacity across 1 generator, operated by Green Mountain Power Corp.
Also known as EIA plant 50704
Analyst: free account, 1 question a day.
Key facts
- Capacity
- 1.3 MWNameplate
- Generators
- 1 operatingEIA-860M, August 2026
- Operating since
- July 1985First generator online
- Operator
- Green Mountain Power CorpEIA operator ID 7601
- Grid
- ISO-NEBalancing authority ISNE
- Price nodes
- 1 ISONE nodeResource nodes with prices
- Location
- Strafford County, NH43.2511, −70.8408
- EIA plant ID
- 50704EIA plant page
Data as of EIA-860M August 2026 (published 2026-09-24). Capacity is nameplate, not live output.
How much power Somersworth Lower Great Dam produces
Free · EIA-923Net generation, 2025
498 MWh
498 MWh, final
Capacity factor, 2025
4.4%
2024: 11.7%
January to July 2026
Not reported
Provisional. 0 of 7 months reported
Range, 2015 to 2025
0.5–5.0
GWh a year. Low 2025, high 2023
| Year | Net generation, MWh | Capacity factor | Months reported |
|---|---|---|---|
| 2000 | Not reported | Not reported | 0 of 12 |
| 2001 | 2,390 | Not reported | 12 of 12 |
| 2002 | 914 | Not reported | 12 of 12 |
| 2003 | 4,051 | Not reported | 12 of 12 |
| 2004 | 4,026 | Not reported | 12 of 12 |
| 2005 | 5,206 | Not reported | 12 of 12 |
| 2006 | 4,824 | Not reported | 12 of 12 |
| 2007 | 3,340 | Not reported | 12 of 12 |
| 2008 | 5,136 | Not reported | 12 of 12 |
| 2009 | 4,501 | Not reported | 12 of 12 |
| 2010 | 3,356 | 29.5% | 12 of 12 |
| 2011 | 5,182 | 45.5% | 12 of 12 |
| 2012 | 3,844 | 33.7% | 12 of 12 |
| 2013 | 3,996 | 35.1% | 12 of 12 |
| 2014 | 2,421 | 21.3% | 12 of 12 |
| 2015 | 2,509 | 22.0% | 12 of 12 |
| 2016 | 2,625 | 23.0% | 12 of 12 |
| 2017 | 1,821 | 16.0% | 12 of 12 |
| 2018 | 3,444 | 30.2% | 12 of 12 |
| 2019 | 3,397 | 29.8% | 12 of 12 |
| 2020 | 2,089 | 18.3% | 12 of 12 |
| 2021 | 1,850 | 16.2% | 12 of 12 |
| 2022 | 1,613 | 14.2% | 12 of 12 |
| 2023 | 4,956 | 43.5% | 12 of 12 |
| 2024 | 1,331 | 11.7% | 12 of 12 |
| 2025 | 498 | 4.4% | 12 of 12 |
| 2026 (provisional, partial year) | Not reported | Not reported | 0 of 7 |
* 2026 covers January to July and is provisional. Capacity factor is net generation divided by nameplate capacity times the hours of each reported month.
Power prices and basis
Free account · ISONEEmissions
Free · EPA CAMPDNo EPA emissions units are linked to this plant.
Water use
Free · EIA-923 cooling, USGSNo EIA cooling-water record for this plant in 2024. Plants without steam cooling, such as wind, solar and batteries, do not report cooling water.
Generators
Free · EIA-860M| Generator | Technology | Nameplate MW | Online since |
|---|---|---|---|
| GEN1 | Conventional Hydroelectric | 1.3 | July 1985 |
Ownership and offtake
ProOwnership and offtake are part of Pro
Owners and their shares, parent companies, and power purchase agreements with their buyers. EIA-860M lists Green Mountain Power Corp as the operator, which is not always the owner.
Modeled data
ProPro adds modeled values for this plant. Everything above stays free.
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Questions about Somersworth Lower Great Dam
How much power does Somersworth Lower Great Dam produce?
Somersworth Lower Great Dam reported 498 MWh (498 MWh) of net generation in 2025, a 4.4% capacity factor on 1.3 MW of nameplate capacity.
Where is Somersworth Lower Great Dam?
Somersworth Lower Great Dam is in Strafford County, New Hampshire, at 43.2511, −70.8408. It is in the ISO New England Inc. balancing area (ISNE).
Who operates Somersworth Lower Great Dam?
EIA-860M for August 2026 lists Green Mountain Power Corp as the operator (EIA operator ID 7601). The operator is not always the owner.
When did Somersworth Lower Great Dam start operating?
Its first generator began operating in July 1985, according to EIA-860M.
Does InfraMap have power prices for Somersworth Lower Great Dam?
Yes. InfraMap has ISONE day-ahead and real-time prices at 1 price node linked to Somersworth Lower Great Dam, with the hub price and node-to-hub basis. Prices are free with an InfraMap account; pricing node names are part of InfraMap Pro.
Sources
- EIA-860 2025 (final) and EIA-860M August 2026: plant, generators, capacity, operator and location
- EIA-923 monthly net generation, 2000 to July 2026 (2026 provisional)
- ISONE day-ahead and real-time prices; node and hub assignments as of 2026-10-05
Page updated 2026-10-04 from the InfraMap data build. Methodology · Data sources · EIA plant page