Connecticut River Flow Restoration Report Released

Connecticut River major tribuatary dams

Scientists with the recently renamed Northeast Climate Adaptation Science Center (NE CASC), The Nature Conservancy and the U.S. Army Corps of Engineers this week released a new study of dam operations and river flows in the four-state Connecticut River watershed that they hope will provide insights for dam operators and natural resource managers as they balance multiple uses and needs of the watershed’s rivers.

The multi-year Connecticut River Flow Restoration Study investigated dam operations and river flows for the 73 largest dams in the Connecticut River watershed in Vermont, New Hampshire, Massachusetts and Connecticut, according to the Corps of Engineers. The corps’ New England District operates 14 flood risk management dams in the basin.

Richard Palmer, university director of the NE CASC, department head and professor of civil and environmental engineering, says, “This study gave our department the opportunity to use our depth of experience in water modeling to tackle the most complex modeling problems we’ve ever attempted. It also provided a wonderful learning platform for dozens of masters and doctoral students. We were proud to be a partner and we are hopeful that this study will be the foundation of potential re-management of the systems of reservoirs in the Connecticut basin in the future.”

The study aimed to evaluate the feasibility of operational changes at large dams in the watershed to benefit ecological health and function while maintaining important services provided by dams, such as flood risk management, hydropower, water supply and recreation. Various tools such as operation and optimization computer models were developed to assess current and potential future dam management scenarios.

The Connecticut River watershed has more than 3,000 dams that have had significant impact on ecosystems, including migratory fish, floodplain forests and rare and endangered aquatic species like dwarf wedgemussel and puritan tiger beetle, researchers say. Impacts include changes such as elimination of natural high flow events that are important for transporting nutrients and sediments to healthy floodplain forests, and increases in short-term flow fluctuations that can significantly alter habitat for fish and aquatic invertebrates. 

The study examined ways in which the largest dams have contributed to alter the natural pattern of water flow in the Connecticut and its tributaries, and how the operation of these dams might be changed to restore the health and function of the ecosystem in the future. 

To better understand the watershed’s pattern of water flow and identify ways to better manage its dams for human uses and ecological needs, researchers interviewed stakeholder groups and dam owners and operators about river uses and needs and developed several basin-wide hydrologic models to support resource management and decision making. These tools will be used to help decision makers and other stakeholders understand the positive and negative environmental, economic and social consequences of various management options. This will in turn help to determine how management of these dams can be modified for environmental benefits while maintaining beneficial human uses such as water supply, flood risk management and hydropower generation.

Katie Kennedy, applied river scientist with The Nature Conservancy’s Connecticut River Program, said, “The results of the study will provide water managers and natural resource experts with new tools to make difficult water allocation and management decisions pertaining to dam management. The Nature Conservancy will be using these tools to find science-based water management solutions that provide benefits for nature while continuing to provide the important services of existing infrastructure.”