Removal of Dams Depends on Community Situation

By GLORIA KOSTADINOVA/ecoRI News contributor

Pawtucket’s Slater Mill was built in 1793 on the banks of the Blackstone River. (ecoRI News)

Pawtucket’s Slater Mill was built in 1793 on the banks of the Blackstone River. (ecoRI News)

Tucked away in the historic town of Pawtucket, R.I., just north of Pawtucket Falls, is iconic Slater Mill. Known as the birthplace of the Industrial Revolution, Pawtucket is home to the nation’s first successful cotton mill. Slater Mill, built in 1793, lies on 4 acres of parkland surrounding two dams and embracing the banks of the Blackstone River. This National Historic Landmark is just one of many historic dam sites across Rhode Island.

In fact, New England is home to an estimated 14,000 small dams that measure less than 10 feet wide. Rhode Island, while the smallest state, houses nearly 700 of those dams, including The Old Stone Dam in Lower Hope Valley, Potter Mill Dam in Westerly and the Snuff Mill at the Gilbert Stuart Birthplace and Museum in Saunderstown.

It’s difficult to image Rhode Island’s Colonial charm without its iconic mills and historic structures, reminiscent of the state’s thriving textile industry. However, despite the cultural and aesthetic values of these sites, dams have proved to be contentious within many New England communities. The important human and ecological dimensions of dams bring a wide range of stakeholders to the table when considering the region’s fate of outdated and neglected structures.

“Here in New England we have lots and lots of tiny dams that are interrupting river connectivity in some significant ways, yet providing cultural values in other ways,” said Caroline Druschke, associate professor of writing and rhetoric and natural resources science at the University of Rhode Island.

With a joint appointment between the College of the Environment and Life Sciences (CELS) and the Harrington School of Communication and Media, Druschke explores the intersection of human and ecological landscapes, drawing on her expertise with community-based writing and rhetoric.

As part of a $6 million federal grant to study the future of New England dams, Druschke and other CELS faculty are examining the social, economic and environmental tradeoffs that are involved in removing and repairing outdated dams. The four-year National Science Foundation grant aims to use the local knowledge and expertise of diverse stakeholders representing government, business and industry, and non-governmental organizations.

“A lot of research points to dams as areas of conflict and the need for interdisciplinary collaboration when examining dam removal, so taking into consideration the social, political, economic and social justice issues [is critical],” said Emma Lundberg, a graduate research assistant with the Future of Dams project.

Lundberg, a Ph.D. candidate in the Department of Biological and Environmental Sciences at URI, examines the public discourse associated with dams and how human dimensions and communication research can play a role in understanding what communities think about dams.

Some of the Lundberg’s fieldwork in Pawtucket involves conducting interviews with federal and state restoration managers, understanding dam removal decisions and stakeholder engagement.

“Much of the discussion in New England has been primarily thinking about the tradeoffs between migratory fish passages and the cultural aesthetics of dams and mill villages,” Druschke said.

According to a recent paper published from Future of Dams works, “Dams stymie migratory fish passage, eliminating or degrading vast expanses of aquatic habitats in coastal watersheds.”

The authors of the report, including Arthur Gold, professor of natural resources science at URI, find that this loss of connectivity between estuaries and watersheds affects aquatic plant and animal life across multiple levels of an ecosystem. These disturbances result in negative consequences for the economics, sustainability and biodiversity of fisheries.

The paper, published by the Multidisciplinary Digital Publishing Institute (MDPI), examined 7,550 dams in New England and the respective costs and benefits of dam removal.

As fish are highly dependent upon the characteristics of their aquatic habitat, the construction of a dam can block or delay upstream fish migration. According to the Food and Agriculture Organization’s Fisheries and Aquaculture Management Division, such hindrance can contribute to the decline and even the extinction of species that depend on migratory passage.

But, as Future of Dams work illuminates, fish aren’t the only beneficiaries of dam removal. The discussion of dam removal is also one about human safety.

“There are around forty or so high-hazard dams in Rhode Island,” Lundberg said. If they breach, high-hazard dams could cause significant harm to private property and human life. “There are a lot of old dams and structures that are obviously breaking down, so dam decisions need to be made,” Lundberg asserts.

Dozens of aging dams in Rhode Island require significant repair and maintenance. In fact, many of them are in high-risk areas, and failure could death and catastrophic damage, according to the Rhode Island Department of Environmental Management (DEM). By definition a high-hazard dam means “a dam where failure or misoperation will result in a probable loss of human life.” In 2015, DEM found 96 high-hazard dams across the state.

“The dams in the state are mostly over 100 years old,” said David Chopy, chief of DEM’s Office of Compliance and Inspection.

With climate change exacerbating severe storms and weather patterns, these outdated structures are at even greater risk of breaching.

“The storms that we’re getting are becoming more intense ... our dams aren’t designed to handle that kind of water,” Chopy said.

Rhode Island has already suffered the consequences of ill-maintained dams. During the historic floods of 2010, five of the state’s dams washed out, two of which were significant-hazard dams.

While dam removal often generates improvements to public safety and migratory fish passage, there are several reasons maintaining dams can be beneficial. In addition to their aesthetic and cultural values, dams can also help mitigate nitrogen build up and eutrophication, a form of water pollution, in coastal watersheds.

The increased use of nitrogen fertilizers in agriculture and sewage associated with rapid urbanization has led to higher nitrogen levels in the waters of the Northeast. This additional nitrogen seeps into small streams and ponds and eventually finds its way to estuaries, where rivers meet the sea. Eutrophication occurs when high levels of nitrogen in these waters stimulate algae blooms, which create low oxygen levels that can kill large numbers of fish. Just as humans need clean air to live, healthy aquatic life also depends on oxygen-rich estuaries for survival.

In the MDPI paper, “Will Dam Removal Increase Nitrogen Flux to Estuaries,” Gold examined the potential for reservoirs associated with dams to remove high levels of nitrogen from coastal watersheds. Studies show that reservoirs both big and small can be important locations for nitrogen removal.

The authors wrote, “We focused our study on situations where dam removal may create a marked change in the watershed nitrogen to downstream waters.” The research results show that some 29 percent of all New England dams serve as nitrogen removal sites; moreover, the authors determined that these nitrogen-removal dams are primarily located on smaller streams.

The paper’s authors carefully considered all of the tradeoffs, noting that removal of some dams will generate benefits for both improved public safety and migratory fish restoration, But, the authors emphasized that dam removal could represent a loss of a reservoir’s capacity for nitrogen removal. Alternative solutions — improvements in stream restoration, septic system technologies and/or agricultural practices — do exist, but they come with a price.

“People feel very strongly in different ways about removing dams ... so it’s not an easy answer,” Lundberg said. “It’s much more situational.”