Case Study

Pawtuxet Falls Dam Removal

Project Summary

In the 19th century, dams constructed along the Pawtuxet River helped to power Rhode Island’s textile industry. Years of industrial use, including the release of untreated chemicals from the Ciba-Geigy chemical plant, left the river heavily polluted. Poor water quality led to declines in fish population and river access for the local community. After decades of investments aimed at improving water quality and habitat in the river, the decision was made to remove the Pawtuxet Falls Dam. For hundreds of years, the Pawtuxet Falls Dam blocked migratory fish passage as the first of many dams leading from the Narragansett Bay through the mill towns situated along the river.

Challenges

There were multiple hurdles that needed to be overcome before the dam could be removed. Design issues were complicated as stakeholders wished to minimize changes to the river’s morphology. However, bedrock in the area was not stable enough to safely navigate river herring upstream and allow for a full dam removal. The water quality and sediment were degraded by more than a century’s worth of upstream discharge of human and industrial waste, including the hazardous waste. Furthermore, at the time, it would have been the largest ecological dam removal undertaken in Rhode Island. Lastly, Pawtuxet Falls Dam was in a highly visible historic location and the dam and waterfall were part of the local landscape and sense of place.

Solutions

In 2011, a project led by the Pawtuxet River Authority and Narragansett Bay Estuary Program, along with dozens of partners, used excavators to strategically demolish the concrete spillway. Native wetland plantings were installed along the newly exposed river banks to aid habitat restoration goals. Today, anadromous fish populations like river herring and American shad are once again able to travel upstream to spawn. This project employed a process of ongoing public interaction, including advocacy on the part of a local business owner. Eight public meetings were held over four years, during which time, assessments and design plans were completed. During this process, the design was modified due to the bedrock conditions. The final design resulted in a portion of the dam staying in place to divert flow and fish in a way that promotes successful upstream migration.

Successes

A NOAA representative reflecting on the process asserted that the biggest hurdle was consensus-building. Ultimately, community consensus was reached, and for the first time in three hundred years, this section of the river was able to flow freely into Narragansett Bay, restoring 7.5 miles of spawning habitat above the dam.

Lessons Learned

For highly visible dams, the public process is very important to build an understanding of the project trade offs and the varying community interests.

References and Additional Resources

NBEP presentation: https://scholarworks.umass.edu/cgi/viewcontent.cgi?article=1212&context=fishpassage_conference
Cranston Herald Article: https://cranstononline.com/stories/village-celebrates-dam-removal-opening-pawtuxet-to-migratory-fish,63352

The Dam Atlas is a guide for communities to understand, evaluate, and make decisions about historic dams.

New England is home to more than 14,000 dams, many of which are small, “legacy” structures built over a century ago. Most no longer serve their original industrial purposes and are reaching the end of their useful lives, raising concerns about safety, maintenance, and ecological impacts. These aging dams can threaten downstream communities, especially as climate change brings more frequent and intense storms. While dam removal is often advocated for ecological, economic, and safety reasons—such as restoring fish passage, water quality, and sediment flow—many communities feel a strong attachment to their local dams. Dams and their impoundments have become part of the landscape, local history, and sense of place, sometimes even serving as town landmarks or symbols of cultural identity.

The goal of this website is to share this work and support communities who are making decisions about the future of a dam. Decisions about dams are inherently complex and require the consideration of ecological, social, safety, and economic trade-offs. While there are many great resources and publications for proponents of dam removal, this website aims to provide an unbiased source of information on the ecological and social considerations associated with dam decisions. Rather than advocating solely for removal, the goal of this approach is to bring a community into an open conversation to think creatively about the future of a dam. While this may seem counterintuitive if your role is to advocate for dam removal, engaging communities in an open but structured discussion about the future of a dam has the potential to lead to better environmental outcomes and a community that has more ownership, connection, and sense of stewardship over their river. In addition, this approach has the potential to address what are often perceived as unequal power dynamics between dam removal proponents and the local community, which has led to projects stalling or failing in the past.

This website consists of four main sections: The first chapter, “Understanding Dams,” introduces key ecological, social, infrastructural, and economic factors that are important to consider for the management of dams at the individual and watershed scale. The second part, “Scenarios & Case Studies,” looks at various alternatives for the future of a dam and presents a series of case studies of projects throughout the region. The third chapter, “Making Decisions,” shares methods, ideas, and tools for how to engage in conversations about the future of a dam. The last section, the Interactive Dam Atlas, was developed in collaboration with faculty from the University of Rhode Island and helps to visualize and build a geographic understanding of dams in the Narragansett Bay and Rhode Island coastal watersheds.

While this Dam Atlas is focused on dams in the Narragansett Bay and coastal watersheds of Rhode Island, the metrics calculated in the GIS analysis can be applied to other watersheds, and the decision-making tools are not region-specific. By sharing our methods and the open-source decision support toolkit, the aim is to help support practitioners and communities that are looking for ideas, methods, and techniques for having discussions about the future of a dam. We encourage others to use, test, modify, evolve, and share these methods. Ultimately, the goal is for this work to contribute to a “library of approaches” that are openly shared to build knowledge and techniques to support collaborative environmental decision-making around dams.