Hopkinton Dam Reservoir Report
Last Updated: December 16, 2025
Hopkinton Dam, also known as Hopkinton Lake, is a rockfill dam located in West Hopkinton, New Hampshire.
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Summary
Managed by the US Army Corps of Engineers, the dam was completed in 1962 and primarily serves the purpose of flood risk reduction. It stands at a height of 71 feet and has a hydraulic height of 64 feet, with a storage capacity of 128,000 acre-feet and a drainage area of 382 square miles.
With a spillway width of 300 feet, the dam has a high hazard potential and is subject to regular inspections and emergency action plans. The USACE manages dam-related flood risks by monitoring the dam's condition, engaging with emergency managers and the public, and updating emergency action plans as needed. As severe weather events can lead to dam releases or potential issues, the USACE works diligently to ensure the dam's structural integrity and mitigate any potential risks associated with flooding.
Year Completed |
1962 |
Dam Length |
790 |
Dam Height |
71 |
River Or Stream |
CONTOOCOOK RIVER |
Primary Dam Type |
Rockfill |
Surface Area |
220 |
Hydraulic Height |
64 |
Drainage Area |
382 |
Nid Storage |
128000 |
Structural Height |
71 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
71 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) 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. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
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.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.
Hazard Potential Classification
HighDams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
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.
Low
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.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.
Hopkinton Dam
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