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The Nature Conservancy, U.S. Army Corps of Engineers release Connecticut River Flow Restoration Study Report

Published June 12, 2018

CONCORD, Mass. – A new study of dam operations and river flows in the four-state Connecticut River watershed could provide insights for dam operators and natural resource managers as they balance the multiple uses and needs of the watershed’s rivers.


The Nature Conservancy and the U.S. Army Corps of Engineers, along with the University of Massachusetts Amherst, recently completed the multi-year Connecticut River Flow Restoration Study, which investigated dam operations and river flows for the 73 largest dams throughout the Connecticut River watershed in Vermont, New Hampshire, Massachusetts and Connecticut.


The purpose of the study was 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 Report is available for review at: http://nature.org/ctriverwatershed or http://www.nae.usace.army.mil/Missions/Projects-Topics/Connecticut-River/.


The Connecticut River watershed has more than 3,000 dams that have had significant impact on the watershed’s ecosystem, including its migratory fish, floodplain forests, and rare and endangered aquatic species like dwarf wedgemussel and puritan tiger beetle. These impacts include alterations to the watershed’s natural hydrology, such as elimination of natural high flow events that are important for transporting nutrients and sediments critical 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 of these dams have contributed to the alteration of the natural pattern of water flow in the Connecticut River and its tributaries, and how the operation of these dams might be modified to restore the health and function of the ecosystem in the future. 


In order to better understand the Connecticut River watersheds pattern of water flow and identify ways to better manage its dams for human uses and ecological needs, the Corps of Engineers, The Nature Conservancy and their partners 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.


"This is an excellent example of the Corps of Engineers working with diverse partners and stakeholders to execute a successful study to benefit the region and the residents of Connecticut, Massachusetts, New Hampshire and Vermont," said Col. William M. Conde, commander of the New England District, U.S. Army Corps of Engineers. The Corps operates 14 flood risk management dams in the basin.


“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 learning for dozens of masters and doctoral students,” said Dr. Richard N. Palmer, department head and professor, Department of Civil and Environmental Engineering at the University of Massachusetts Amherst. “We were proud to be a partner and that 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 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,” said Katie Kennedy, applied river scientist with The Nature Conservancy’s Connecticut River Program. “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.”


The Nature Conservancy is already using these tools to assist stakeholders in the current hydropower relicensing process underway in the Connecticut River watershed. In this case and elsewhere, the tools developed for the study have potential to reduce conflict by helping water resource managers and stakeholders understand how water management decisions impact their objectives and the objectives of other parties, and to develop creative options for meeting multiple needs and uses of the river.

Tim Dugan
James Miller

Release no. 18-054