The Case for Dam Removal—Balancing Ecology, Safety, and Economic Viability

February 19, 2025

OARS River Log | By Heather Conkerton, OARS’ Ecological Restoration Coordinator | Published February 19, 2025

At OARS, we advocate for the removal of dams to promote healthier, free-flowing rivers and streams. Our mission is rooted in the belief that natural waterways are cleaner, cooler, and more ecologically connected when allowed to flow without obstruction. We understand that each dam is unique and requires a thorough, individualized assessment. Factors such as the dam’s role in the landscape, historical and scenic value, safety concerns, maintenance costs, and ownership must all be carefully considered. Our goal is to ensure that each decision reflects a balanced understanding of environmental benefits and community needs.

Dam Removal vs Dredging to Address Sediment Buildup

While dredging is often considered to address sediment buildup, it only provides a temporary solution and comes with significant ecological drawbacks. Artificially deepened channels fill up with silt more frequently as they return to their pre-dredged state, making repeated dredging and maintenance a requirement. Dredging can damage ecology by disrupting riverine processes, reducing connectivity with the floodplain, increasing turbidity, and releasing contaminants. It can also destroy benthic habitats, harm aquatic plants by reducing sunlight penetration, and negatively impact species that rely on clear water for navigation and foraging. While there are some situations where this approach makes sense, it is not a permanent solution but, rather, an ongoing maintenance task.

In contrast, dam removal addresses the root causes of sediment buildup by restoring the river’s natural flow and sediment transport processes. In addition, removing a dam allows fish to migrate freely, improves water quality, reduces methane emissions from stagnant reservoirs, and eliminates the need for ongoing dredging and maintenance. This restorative approach not only benefits the ecosystem but also proves more cost-effective in the long run, as it does not require costly ongoing maintenance.

The Costs of Dams

While dams provide benefits, they also bring significant negative consequences, including:

Ecological Disruption: Dams block the movement of fish and aquatic species, disrupt natural river flow, alter water temperature and quality, and impede the transport of nutrients and sediment.
Loss of Wildlife Habitat: Flooded areas behind dams inundate natural habitats, displacing native plants and animals.
Flooding Risks:Many dams were not designed for flood control and can increase flood risks if they are in disrepair or mismanaged.
Economic Liabilities:Maintaining aging dams require costly repairs, while obsolete dams provide little economic return.
Public Safety Hazards: Many outdated dams pose significant risks, as failures can cause catastrophic flooding and loss of life.

The Benefits of Dam Removal

Removing dams can yield multiple environmental, economic, and social benefits, including:

Restoration of Natural River Ecosystems: Dam removal can improve water quality, re-establish natural sediment flow, and restore fish migration patterns.
Revitalization of Fisheries and Wildlife: Removing barriers allows fish populations, including, in some cases, salmon, sturgeon, and trout, to recover and thrive.
Enhanced Public Safety: Eliminating structurally deficient dams reduces the risk of catastrophic failures and drowning incidents at low-head dams.
Economic Savings: Dam removal is often 3–5 times less expensive than repair and ongoing maintenance.
Increased Recreational Opportunities: Free-flowing rivers offer better fishing, boating, and overall outdoor experiences.
Climate Resilience:Removing dams can lower water temperatures, improve dissolved oxygen levels, and reduce methane emissions from stagnant reservoirs.

Indigenous Peoples and Dam Removal

For many Indigenous communities, rivers are not just resources but living entities with cultural, spiritual, and ecological significance. The construction of dams has historically led to the displacement of Native communities, destruction of sacred sites, and disruption of traditional fishing practices. As a result, many Indigenous groups have been at the forefront of dam removal efforts, advocating for the restoration of free-flowing rivers as an act of environmental justice and cultural revival¹^,²^,³^,⁴^,⁵.

Dam removal means:

Restoration of Tribal Fishing Rights: Many tribes historically relied on fish for sustenance, and dam removal helps restore these essential fisheries.
Reclaiming Sacred and Ancestral Lands: Removing dams can reveal landscapes that were once vital to Native communities, allowing for cultural reconnection and traditional practices to resume.
Honoring Environmental Stewardship:Indigenous knowledge emphasizes the interdependence of all life, and dam removal aligns with traditional ecological values of maintaining healthy rivers.
Legal and Political Advocacy: Many tribal nations have used legal action and political engagement to push for dam removals, emphasizing treaty rights and environmental justice.

Traditional lands of tribes in MA. Image credit: Native Land Digital

To learn more about the traditional territories of Indigenous peoples in your area, visit Native Land Digital, an interactive map that identifies Indigenous lands across North America and beyond.

Addressing Common Concerns About Dam Removal

River Size and Flow: Rivers typically return to their natural width and depth after dam removal rather than turning into small trickles.
Flooding:Most dams were not designed for flood control, and their removal often reduces downstream flood risks.
Sediment Management:While dam removal may initially release accumulated sediment, studies have shown that rivers recover naturally within days to years, with minimal long-term impact.
Property Values:While some fear declining property values, studies indicate that many riverfront properties retain or even increase in value post-removal due to enhanced river health and recreational appeal.
Historical Value: Only a small number of dams hold official historic status, and preservation concerns can often be addressed through documentation and alternative historical recognition methods.

The Future of Dam Management in Massachusetts

With more than 3,000 dams in Massachusetts, most of which no longer serve their intended purpose, dam removal presents an effective strategy for river restoration. Federal, state, and private funding sources are increasingly available to support responsible removals, ensuring ecological and economic benefits for future generations.

Removing outdated and unnecessary dams is the fastest way to heal a river, protect communities, and support resilient ecosystems. As climate change continues to impact water systems, prioritizing free-flowing rivers will be essential to sustaining both human and environmental health.

LEARN MORE ABOUT OARS DAM INITIATIVES

River Log

~30%

of the SuAsCo rivers watershed is wetlands, crucial for wildlife habitat and water quality

~30%

of water samples in the SuAsCo rivers watershed contain PFAS, leading to increased monitoring and remediation by local authorities and environmental groups

~70%

of dams in the SuAsCo watershed are over a century old, requiring extensive upkeep and presenting obstacles to river restoration and fish passage

>40%

of the land within the watershed is publicly accessible, offering recreational opportunities such as hiking, boating, and birdwatching to the community

~15%

of the land in the SuAsCo rivers watershed is covered by impervious surfaces such as roads, rooftops, and parking lots. This contributes to stormwater runoff and water pollution issues

>40%

of the land within the Sudbury, Assabet, and Concord rivers watershed is publicly accessible, providing endless opportunities for paddling, hiking, and wildlife exploration.