Comerford Dam

Comerford Dam is a major hydroelectric and flood control structure on the Connecticut River, forming part of the border between Canaan, Vermont and Northumberland, New Hampshire. Owned and operated by subsidiaries of NextEra Energy Resources, the dam impounds the Moore Reservoir and is a key component of the New England Power Company's generation fleet. Completed in 1930, it was a significant engineering achievement of its era and remains a vital source of renewable energy for the New England grid.

History

The dam's development was spearheaded by the New England Power Company during the late 1920s, a period of rapid industrial expansion and electrification in the Northeastern United States. Its construction was part of a larger series of projects to harness the power of the Connecticut River, following earlier developments like the Vernon Dam. The site was selected for its favorable geology and significant hydraulic head. The dam was named for a prominent local family with historical ties to the region's early settlement and industrial activities. Upon its completion, it immediately became a critical infrastructure asset, supporting the growing energy demands of cities like Boston and Springfield, Massachusetts.

Design and construction

Comerford Dam is a concrete gravity dam standing approximately 175 feet high and 1,800 feet long. Its design was overseen by the engineering firm Stone & Webster, which employed advanced techniques for mass concrete placement. The structure incorporates a gated spillway with several tainter gates to manage reservoir levels and a powerhouse integral to the dam's base. Construction, which began in 1928, required a large workforce and the creation of extensive cofferdams to divert the Connecticut River. Key materials, including cement and aggregate, were sourced locally. The project also involved the relocation of a segment of the Boston and Maine Railroad.

Operations and purpose

The primary operational purposes are hydroelectric power generation and flood control along the upper Connecticut River Valley. The facility's powerhouse contains three Francis turbine generators with a combined capacity of 90 megawatts. Operations are managed remotely from a control center, with water releases coordinated with upstream dams like McIndoes Dam and downstream facilities such as Moore Dam to optimize river flow for power production and flood mitigation. The dam is a participating unit in the New England Independent System Operator (ISO-NE) electricity market. Its reservoir, Moore Reservoir, also provides limited recreational opportunities, including boating and fishing.

Environmental impact

The creation of Moore Reservoir inundated several thousand acres of terrestrial habitat, altering the local ecosystem and displacing wildlife. The dam presents a barrier to the migration of anadromous fish species, such as Atlantic salmon and American shad, which historically spawned in the upper Connecticut River. Efforts to address this, led by agencies like the U.S. Fish and Wildlife Service and the Connecticut River Atlantic Salmon Commission, have included the construction of fish passage facilities at other projects in the watershed. Reservoir operations can cause downstream water temperature and flow fluctuations, affecting aquatic life. The dam's role in flood control, however, has provided significant protection to downstream communities, including Holyoke, Massachusetts.

See also

* Connecticut River * Moore Dam * Hydroelectricity in the United States * List of dams in New England

Category:Dams in New Hampshire Category:Dams in Vermont Category:Buildings and structures in Grafton County, New Hampshire Category:Dams on the Connecticut River Category:Hydroelectric power plants in New Hampshire