Nashua’s Hydroelectric Plants – Power to the People

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A view of the Mine Falls Dam and the Nashua River. The left side is the headworks structure for the powerplant and to the rear is the historic Mine Falls Gatehouse built in i886. The red-brick structure is an artifact of the power generation history of the river for the city. Photo credit- Dan Splaine Photography

NASHUA ,NH – The origins of Nashua’s prosperity were built on the namesake river that flows through it. In the 1820s the Nashua Manufacturing Company and Jackson Mills began to harness the power it provided in their cotton mills.  Today with those mills a distant memory the river still provides power to the city.

The past meets the present at the two hydroelectric dam facilities that the City of Nashua owns and operates.  These facilities play a key role in the LIVABLE NASHUA PLAN that maps the paths to a more sustainable future for the city.

Mine Falls is a 3-megawatt plant and the Jackson Mill is a 1-megawatt power plant. They generate enough electricity for 2,100 homes using the naturally-occurring flows of the river.

The two power-generating turbines and the control panels in the Mine Falls Hydroelectric Power Plant on the Nashua River. This 3-megawatt power plant is one of two hydro plants operated by the city. Photo credit- Dan Splaine Photography

Deb Chisolm, Sustainability and Waterways Manager oversees the city’s hydroelectric power stations.  Her duties also include the rivers, streams, and ponds in Nashua for issues of public accessibility, clean water, and invasive species among others. She wears a lot of hats, and she says “That makes this job so great because I get to do a lot of different things.” One feature of both dams is the means and methods for fish migration which Chisolm manages.

Beginning in May river herring and later eels will use the fish ladder at Jackson to swim over the dam and get a lift at the Mine Falls site in the fish elevator system.  They monitor fish volume with counting and cameras. “We work with US Fish and Wildlife, NH Fish and Game, and National Marine Fisheries to make sure our fish passage is what the agencies consider adequate”.  Currently, preparations are underway for this year’s migration.

A much larger project underway is the replacement of the turbine at the Jackson Mills Plant. This project has been delayed by the challenges posed by the river flows which have compromised the coffer dam structures.  The wettest year on record (2023) and heavy rains this spring have produced an epic volume of water.  Summer flow rate of about 200 CFS (cubic feet per second) and right now are at about 1000 CFS, a rate five times greater.

Construction has re-started this week on the replacement turbine of the Jackson Mills Hydroelectric Plant. The 1-megawatt powerplant is one of two operated by the city of Nashua. The inset photo shows the recent overflowing of the coffer dam caused by record river flows that have delayed the completion of the project. Photo credit- Dan Splaine Photography

These are Run of River facilities so water speeds and levels influence electrical production. Reliable production requires some flow so when it drops the plants shut down. High water shutdowns can occur because the turbines can’t handle the water pressure involved.

When the city acquired the plants it was not about the economics of the plants but more about doing the right thing.

“ This is renewable energy, this is clean power. The city has invested in upgrades and maintenance. This is something the city is committed to for the future,” says Chisolm. 

Renewable and affordable energy is one of the goals of the sustainability plan.

Matt Sullivan, Director of the Community Development Division commented on the goal for the city to adopt sustainable operations. “The city is taking a position of leadership on sustainability and we believe we can lead by example, taking steps to make the municipal government cleaner, to be greener, and be more energy efficient.”

Changes are occurring incrementally with long-range objectives clearly defined.  “I don’t know if the public knows we have these assets. I think what is also not known is what these facilities actually mean and what they mean long term.  These facilities set us up for success,” Sullivan said.

The mill buildings along the Nashua River have long gone silent and have been converted to non-industrial uses.  They line the river as relics from our past as the river’s flow continues to power the future.

Deb Chisolm, Sustainability and Waterways Manager (left), and Matt Sullivan, Director of the Community Development Division (right) at the Mine Falls Hydroelectric Plant in Nashua, NH. They’re overlooking the diversion canal and sluiceway that supplies water flow into the plant. Photo credit- Dan Splaine Photography

Dan Splaine

DAN SPLAINE – Photographer/Contributor

Nashua native Dan Splaine is a commercial photographer who creates images for businesses. A strong belief in the value of local independent journalism, his Nashua roots, and his extensive background in photojournalism make contributing to the NASHUA INK LINK a natural choice. 

After working in dozens of countries and throughout the US on assignments Dan will happily go local and turn his lens to capture lives and living in the Gate City. You can see his work and learn about his photography services and workshops by going to his website.


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