Hooksett Reservoir Report

Last Updated: December 18, 2025

Hooksett is a private dam located in Merrimack, New Hampshire, along the beautiful Merrimack River.


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Summary

Built in 1927, this masonry dam stands at a height of 11 feet and has a length of 667 feet, with a storage capacity of 1650 acre-feet. The primary purpose of Hooksett is hydroelectric power generation, making it an essential part of the region's energy infrastructure.

Managed by the NHDES Dam Bureau and regulated by the Federal Energy Regulatory Commission, Hooksett is inspected regularly to ensure its safety and efficiency. The dam has a controlled spillway with a width of 615 feet and a low hazard potential. Despite its age, Hooksett remains in good condition, contributing to the risk assessment of "Very High (1)". With its historical significance and important role in water resource management, Hooksett is a key structure for water and climate enthusiasts to study and appreciate.

Year Completed

1927

Dam Length

667

Dam Height

11

River Or Stream

Merrimack River

Primary Dam Type

Masonry

Surface Area

405

Drainage Area

2805

Nid Storage

1650

Outlet Gates

Tainter (radial) - 1

Hazard Potential

Low

Nid Height

11
       
Seasonal Comparison

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Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.