The Watertown Dam. (Photo via Creative Commons/Wikimedia by Andy Dincher)

AT A TIME when “abundance” is a policy mantra and states are focused on launching ambitious construction projects in housing, transit, and energy, the idea of spending millions to tear down infrastructure tied to a town’s history runs against the grain.

Yet on a cold January night, more than 100 people turned out in Watertown for a community meeting to discuss demolishing Watertown Dam, a fixture on the Charles River at Watertown Square since colonial times. A dam that connects a town to its heritage is not easily surrendered.

And Watertown is not unique. Across Massachusetts, communities are confronting a centuries-old legacy that is now doing more harm than good. The preservation of an obsolete dam implicitly privileges colonial and industrial history over a river’s deeper history as living infrastructure.

Massachusetts has about 3,000 dams along its 8,000 miles of rivers. Most were built to drive mills and no longer serve any meaningful economic purpose. Of the 331 dams that are classified as “high hazard potential” — meaning their failure could lead to loss of life or significant property damage — only about half are rated in satisfactory condition.

The near collapse of the Whittenton Pond Dam in Taunton in 2005 rallied public opinion around dam safety and prompted the creation of the Division of Ecological Restoration within the Department of Fish and Game. Dam removal has been a core part of DER’s mission.

Besides flood safety, enabling fish migration is a driving motivation for dam removal. Studies at the Watertown Dam showed that while thousands of alewife and blueback herring ascend its fish ladder every spring, many never find the ladder’s entrance. Species such as American shad are unable to pass. Removing the dam would open the river to all migratory species and lower upstream water levels by six feet during peak flood conditions.

Since 2009, the DER has removed roughly three dams per year, a rate insufficient to address all hazardous dams in marginal condition by the end of the century. Gov. Maura Healey’s Mass Ready Act, a $3.1 billion environmental bond bill now before the Legislature, would begin to address the deferred maintenance crisis by allocating $93.5 million for dam management.

But not everyone wants the dams removed. Although unfettered rivers support ecosystems, regulate temperatures, sustain fisheries, and reduce flood risk, opponents raise valid concerns. Chief among them are the potential release of toxic sediments and the loss of historic landmarks.

When a dam is removed, the sudden flow of water can wash decades of accumulated sediment and legacy contaminants downstream. Engineers mitigate the issue by conducting extensive testing, dredging, or capping as needed, and then lowering the water gradually over months to allow the river to stabilize.

The more contentious objection is the loss of aesthetic and historical value. A placid pond behind a tumbling waterfall lends character to a town’s center and evokes its past. Proposals to dismantle dams can provoke fierce opposition.

Ipswich offers one example. There, debate raged over the removal of the Mills Dam. A citizens group, Save Our Dam, raised concerns about water quality and emphasized the dam’s prominent role in the town’s industrial past. The site was first dammed in 1637, and over time supported a grist mill, a hemp mill, a fish weir, and, in the 19th and early 20th centuries, a major textile mill that employed thousands.

But the Ipswich Historical Commission was skeptical. The commission did not deny the dam’s meaning to many people and agreed that it should be memorialized using various media. But it noted that the current dam was built in the 20th century and used for only 20 years. More pointedly, the commission underscored the dam’s harm to the fishery that sustained Ipswich’s Indigenous Peoples and early settlers.

In Billerica, the fate of the Talbot Mills Dam pits river advocates against the town’s Historic Districts Commission. That dam, dating back to 1711, anchored the town’s industrial identity at the junction of the Concord River and the Middlesex Canal. Historians maintain that removing the dam would “sacrifice our historic heritage…with no guarantee that the project will benefit our residents.”

River advocates see it differently. OARS, the Organization for the Assabet, Sudbury, and Concord Rivers, argues that removing the dam “is not erasing history” but “restoring the river to a more natural and historically accurate state while honoring a much deeper cultural legacy,” including its Indigenous stewardship.

The unbuilding of a legacy dam acknowledges that rivers have a deeper preindustrial history as living infrastructure. Building for the future sometimes requires choosing to restore the natural productivity that existed in an earlier time. By choosing to let the river run free, we recover an abundance too easily ignored.

While the Billerica case raises legitimate concerns, historical significance alone is not a sufficient reason to preserve infrastructure that continues to cause harm. Much of the industrial past remains embodied in mill buildings that still stand.

The deeper question is which history towns like Billerica choose to honor. The run of the river predates the mill.

Frederick Hewett is a Cambridge-based freelance writer focused on energy and climate issues.