There are some 14,000 dams across New England, many of which are vestiges of a long-past era. Some are relatively new and relatively large, like the Wrightsville Dam, constructed during a spate of Depression-era public infrastructure building. But many more were made in a much earlier period, when the New England economy was powered by moving water and when mill-driven factories were built on rivers everywhere, making everything from textiles to chocolate. In many cases, towns and cities grew up around them, leaving antiquated dams in populated centers where people and property could now be at risk.
A federal database cataloging 4,010 of the region’s larger dams lists 533 of them, or 13 percent, as being at risk for failure and, if they do fail, causing significant economic loss or death. About 200 of those are in Massachusetts.
Below, see a map and table of these at-risk dams: Structures that are in “poor” or “unsatisfactory” condition that could cause a threat to lives and property if they were to fail.
About this data
Dam data in this map and table are from the National Inventory of Dams, which is maintained by the US Army Corps of Engineers. The full, nationwide database contains information on more than 91,000 dams. NID data are updated on a rolling basis.
Federal authorities use this category to indicate the potential hazard to the downstream area resulting from failure or mis-operation of the dam. It reflects probable loss of human life as well as economic and environmental impact. The hazard potential does not speak to the condition of the dam or the risk of the dam failing.
Low Hazard Potential: Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner’s property.
Significant Hazard Potential: Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
High Hazard Potential: Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
The category that best describes the condition of the dam based on available information, using a four-level scale: Satisfactory, fair, poor, and unsatisfactory. A dam may also have a designation of “not rated” or “not available.”
Satisfactory: No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair: No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
Poor: A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory: A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.