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State looks to ensure creation of comprehensive historical record if lower Collinsville dam is removed


By John Fitts

Staff Writer

As the state Department of Energy and Environmental Protection moves toward likely removal of the lower Collinsville dam and all related infrastructure, project partners say it’s critically important to preserve a detailed and comprehensive record of the structures.

Last September, DEEP and several consultants came to the Avon Free Public Library for a very detailed presentation about their reasons to seek removal. In addition to safety concerns – particularly after the 2021 drowning deaths of two teens at the site - removal of the Collins Company lower dam would improve the ecology of the Farmington River while opening up miles of watershed to migratory fish, an important step in the recovery of spawning populations of American Shad, Alewife and Blueback Herring, according to DEEP officials and their partners in the potential project. The potential dam removal is part of a larger effort to solve fish passage issues clear to the confluence of the Farmington River with the Connecticut. The latter remains dam between that confluence and Long Island Sound.

On July 2, members of DEEP, other state offices and additional consultants returned to the library for another kind of meeting.

At the more recent meeting officials said there is no final timeline or price tag for the project and made it clear that the evening was focused on the topic of mitigation – specifically “Section 106 of the National Historic Preservation Act and potential mitigation measures for the proposed removal of the Collins Company Lower Dam.”

That “mitigation” could come in many forms, such as interpretive signage and pieces mechanical components along the Farmington River trail, pamphlets in print and digital form and a comprehensive documentation process that would be overseen by the National Parks Service and incorporated into the Library of Congress. The latter is known as HABS/HAER/HALS – which stands for Historic American Building Survey, Historic Engineering Record, Historic American Landscape Survey.

An overview of the lower Collinsville dam system as included in the July 2 presentation.


The lower Collinsville dam was part of a much larger picture of how the Collins Company used waterpower to operate the machinery used to craft edge tools sold around the world from 1826 to 1966.

 “Waterpower was absolutely vital to success, to the growth, the international extent of the Collins Company,” Bruce Harvey of Harvey Research and Consulting said at the most recent meeting.

As noted in “The Collins Company of Collinsville, Connecticut,” a historical book with information compiled by Thomas Dunmore Ayer, Kathleen McLeod Taylor and photographer Gregory Kriss, the effort started upon the company’s founding in 1826 with the purchase of the Humphrey Sawmill and Grist Mill, a transaction that included water rights and construction of a log dam on the east side of the Farmington River.

A stone wall followed a year later, working to keep water from an old stone shop building while also diverting water to power the venture.

“This allowed water to be channeled through this building to power early water wheels that drove bellows, trip hammers and grindstones,” the book notes.

 In 1837, the company built its first cross-river dam.

“By the later 1830s – [the company] built their first dam across the river – a stone dam, which more effective and could shunt more water, which meant more power to power more gears and more equipment,” said Harvey, who is a Historian and HABS/HAER/HALS Photographer.

The efforts continued and by the 1860s, the company worked on a plan to generate a more predictable flow of water.

“The Collins company joined with a couple of other companies to develop the Otis reservoir in Massachusetts,” Harvey said. “They were trying to ensure themselves a steady flow of water. What a manufacturing company needs is steady water. They need steady power and since they were relying only on waterpower at the time, they needed that steady flow.”

The current 300-foot-long Upper Collinsville stone dam – embedded in the river bedrock – was built in 1867. The hydroelectric outfitted powerhouse was added in 1935.A gate controlled forebay (or reservoir) diverted water from the river through a complex series of waterways and infrastructure that powered equipment in many buildings throughout the complex before returning it to the river.

While the company was by then also vested in coal power, the early 20th century brought an interest in hydro-electric power.

The idea for the lower Collinsville dam, which is one mile downstream from the upper dam, came circa 1907, Harvey said.

“The idea was, by that time in the early 20th century, hydroelectric power was. … becoming more available, the technology was developing. The idea was they would develop a hydroelectric facility downstream to supplement the work at the manufacturing plant,” Harvey said. “That’s where the lower dam comes into play.”

After some initial plans, the project moved forward after 1910 with design, engineering and property acquisition, Harvey said. Surveying came in 1911 and construction began in August of 1912 and was largely complete in 1913 and fully so by 1914. According to the Collins Company book, construction was done by the Boston based Holbrook, Cabot & Rollins Corporation.


“There were several purposes to have the lower dam,” Harvey said. “One was they could build it for hydroelectric power. They had lines that then ran to the generating station back up to the plant and it would help them to reduce the need for coal fired steam plants. Coal was expensive and you had the one-time cost of the …hydroelectric plant. You can supplement less expensively.”

Once the upper dam infrastructure included hydropower in the 1930s, the company had flexibility, he said.

“In times of high water, the company could make use of the same water twice … so they could double dip. …In times of lower water, they would let the water flow through the upper dam, pond at the lower dam where they could generate hydroelectricity – so it had sort of a three-prong purpose. It was really quite an ingenious design, especially that early in the history of hydroelectric power in America. This is really very early.”

The lower dam

The lower Collinsville dam infrastructure spans 400 feet across between Avon and Burlington.

The dam spillway – over which water flows sometimes with flashboards to raise the head level - is 300 feet across the river.

One the west side of the river are 40-foot sluice gate wall with mechanicals that controlled three four-foot square outlets on the bottom of the dam headwall. Those could be raised and lowered manually to draw down the impoundment level when needed - such as in flood conditions or for maintenance.

On the east side is a concrete abutment 60 feet from the end of the spillway to the bank. On top of the abutment is the brick gatehouse where six, 6- by 8-foot gated openings – also manually controlled by gears and now locked shut – regulated flow through a canal (also called a headrace) down to the powerhouse.

The canal, set between a concrete wall along the river and masonry stone blocks along the bank, was built to get a greater drop in water level, which allows for more power generation.

From the canal, water flowed into two intakes in the concrete sub structure under the powerhouse. The powerhouse had two had two generating units – each with a water wheel below floor level water come into chamber and as it went through a draft tube out to river would spin a wheel – or turbine. Those were connected through shafts to generating units that creates electrical energy which was then transmitted to “step-down facility” and then up to factory.

When the Collins Co. closed in 1966, there was much discussion about water rights, Harvey said.


“By early 1967 The Hartford Electric Co. which had been buying and selling with Collins Co. …. closed on deal to purchase the water rights including both dams and both hydroelectric facilities,” Harvey said.

The company, however, soon conveyed the facilities and rights to the state, determining re-energizing the dams were not feasible for their purposes, Harvey said.

Since the 1970s, many have looked at re-energizing the dams. The upper dam – still owned by the state by regulated by the Federal Energy Regulatory Commission - was re-energized by Canton Hydro, LLC in 2023, after it responded to a 2015 Request for Proposal from the town of Canton. (The town worked on the project for several years, going through a few iterations and eventually opting to allow a private entity – rather than a public/private partnership - run the facility.

At the lower dam, the power company did remove the electrical generating and control equipment, Harvey said. The company did keep land near the river and 34 acres there is still listed as being owned by Connecticut Light and Power (Eversource).

The Federal Energy Regulatory Commission has issued at least two preliminary licenses for the lower dam, but most studies and entities have questioned the economics of re-energizing the lower dam, according to officials.

“It has been looked at by multiple entities, but it’s just not feasible,” Ramona Goode, a sanitary engineer for state dams at DEEP, who is serving as project manager, said later in the meeting. Earlier in the meeting she also noted that the state still owns the dam and is responsible for day-to-day operation, including maintenance and oversight of any repairs, construction or upgrades.

This slide shows how communities often incorporate mechanical components from a site into interpretive sign displays..

Resolving adverse effects

At the July 2 meeting, DEEP, along with project consultants, reviewed ideas, gathered input and provided context on the goal of “resolving the adverse effects” of removal.

Matthew Spigelman Archeologist and Principal of ACME Heritage Consultants, said The National Historic Preservation Act of 1966, resulted from the destruction of historical sites and buildings caused the building of highways and other major infrastructure initiatives.

 “It’s part of the mid-century questioning of what should we save – and how should we remember and study what we can’t save,” Spigelman said.

The act created many entities including State Historic Preservation Offices and the National Register of Historic Places.

When it comes to Section 106 he noted “Federal agencies shall take into account the effect if their undertakings on any district, site, building, structure, or object that is included in or eligible for inclusion in the National Register of Historic Places.”


And importantly, Spigelman noted, the State Historic Preservation Office has determined that while the lower dam was not included on the historic register, it would be eligible.

As a result, it is critical that the project include ways to resolve the adverse effects of dam removal, he said. As a slide in the evening’s presentation noted, the State Historic Preservation Office wrote, “Based on the information provided, SHPO has concluded that the proposed project will have an adverse effect to historic properties.”

“The first step to resolve adverse effects is to develop mitigation – that’s some method of counteracting the negative effect,” said Spigelman. He noted that the evening would involve a review of “possible options that have been used – that begins the process of talking of what mitigation would be appreciated, meaningful and provide the mitigation that will resolve the adverse effect.”

Spigelman talked in detail about the consulting process and how the State Historic Preservation Office and other parties are notified and then how the process moves through identification, assessment and resolution phases.

The process is done for both Architectural and Industrial aspects as well as archeological aspects. SHPO, however, determined the project did not warrant archaeological investigations.

As for the Architectural and Industrial investigation, The State Historic Preservation Office determined, “Although the lower dam is not as old as the upper dam, it also was a part of the Collins Company operations and described in a letter from our office dated May 17, 1995, as stating, in part, “integrally associated with Collinsville’s industrial heritage and Eligible for the national register.’ Additionally, SHPO affirms its prior opinion that the lower Collinsville dam and its related facilities are eligible for listing in the National Register of Historic Places.”

Later in the meeting, Spigelman addressed some ideas for the project, often referring to examples used in other places.

One of the most visual components under consideration is interpretive signage, which often includes pictures, text and even graphically representations of the inner workings of a site. In this case, that would likely be placed along the Farmington River trail on the Burlington side of the lower Collinsville dam.

“It’s a way to preserve and present, in a public setting, the larger context of the dam itself and the records of the dam,” Spigelman said.

In addition to the signage itself, many sites also incorporate mechanical components used at the site.

Additionally, the project could include pamphlets in digital and print formats and articles in scholarly journals, Spigelman noted.


Harvey spoke to that HABS/HAER/HALS process and noted how much historians loved acronyms.

He spoke to some of the history of the process, noting for example, that HABS grew out of the Works Progress Administration established during the Great Depression.

“It was a combination of early historic preservation efforts when a number of historians and other active members of the community realized that in this onboard rush of progress we were losing some of the tangible reminders of the nation’s history,” he said. “So, the measured drawings were a way to record them before they went away. It was a way also to put some architects to work.

Soon, photographers became involved in the effort and while the programs faltered during World War II, the boom years that followed also came with a renewed recognition that historical sites were being lost to highway construction, city expansion and suburban booms.

The 1960s brought more awareness of other components such as social and labor efforts and the National Parks Service created HAER in 1969.

HABS/HAER/HALS documentation comes in many levels but for the lower Collinsville Dam project it would be at the most involved designation – or Level 1 - meaning the project would include a full set of measured drawings, a “full-outline format historical report” and large format black and white photographs. Eventually that would all available in digitized format through the Library of Congress.

“These memories they get embedded in landscapes they are imbedded into buildings, but when those go away finding other ways of retaining these memories,” Harvey said. “The HABS/HAER and HALS program is just phenomenal – just an amazing resource for that kind process of preserving memories on a nationwide basis.”

Later in the meeting, Catherine Labadia, Staff Archeologist State Historic Preservation Office addressed why the office felt it rose to that level, even though the lower dam was not included in a National Register of Historic Place application is the mid 70s.

“We spent a lot of time talking about this HAER document. That’s my request. That is a technical document that I think we need to have but mitigation is really about how you compensate the community for loss. You have this fantastic historic feature. It’s HAER level 1 because I called the Parks Service and I said I have this amazing thing; it’s not on the national register, it was never recognized when the nomination was originally put together. I think it’s a high level of significance not locally, not at the state level but at the national level. … We kind of bantered back and forth and the Parks service said, ‘you know what? We agree with you we think this is a nationally significant feature that was missed as part of the original nomination, and we are requesting that you do a Level 1 documentation.’”

 “It makes sense,” Labadia added. “This is an important piece of history that we’re going to lose and so when we think about what mitigation is, we want to think about what we can give back to the community for that loss. The HAER is great for me. It means something to all of us historical preservationists who spend hours on the Library of Congress looking at pictures, but it also needs to be something for the community and signage, booklets – all those things are really great, but we always like to think about something that’s more creative. How do we capture the history, how do we capture that memory? Where does it get displayed. How does it get displayed?”

Labadia also said discussions about the proposal to remove the entire dam infrastructure were taken seriously.

 “We did go through a discussion about trying to maintain as many historic components of the dam as possible. Could we keep a portion of the dam? Could we keep some of the buildings? The truth is the buildings unfortunately are on a side of the river that are inaccessible so there will never be a way to put them into use or interpret them and they just become a liability to DEEP, so our office did say we understand where you’re coming from on that.”

Labadia also said the 106 process is a conversation and as DEEP moves toward a potential memorandum of understanding with SHPO on mitigation, she urged residents to send any and all suggestions their way.

Those can be sent to Goode at, DEEP state dams environmental analyst Charlie Brown at or Labadia

See our coverage of the meeting last September here.

This slide shows an example of the drawings in the HAER process. (Note: this is not from the Collinsville structure)

This slide shows an example of the photographic documentation used in the HAER documentation.








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