Macallen Dam Reservoir Report

Last Updated: December 15, 2025

Located in Newmarket, New Hampshire, the Macallen Dam stands as a testament to the engineering ingenuity of its time, having been completed in 1887.


°F

°F

mph

Wind

%

Humidity

Summary

This concrete buttress dam spans 150 feet in length and reaches a height of 27 feet, providing a storage capacity of 1740 acre-feet along the Lamprey River. With a primary purpose of recreation, the dam offers a surface area of 120 acres for water enthusiasts to enjoy various activities.

Despite its historical significance and recreational value, the Macallen Dam poses a high hazard potential and has been assessed as being in poor condition as of June 2016. Regular inspections are conducted, with the latest one taking place in September 2020, to ensure the safety of the surrounding communities. While the risk assessment deems the dam to have a moderate risk level, there is ongoing monitoring and management measures in place to safeguard against potential emergencies and mitigate any risks associated with its operation.

Managed by the local government and regulated by the NHDES Dam Bureau, the Macallen Dam not only serves as a recreational hub but also plays a crucial role in water resource management and climate resilience efforts in the region. As water resource and climate enthusiasts, it is important to stay informed about the state of infrastructure like the Macallen Dam to support sustainable practices and ensure the preservation of vital water resources for future generations.

Year Completed

1887

Dam Length

150

Dam Height

27

River Or Stream

LAMPREY RIVER

Primary Dam Type

Concrete

Surface Area

120

Drainage Area

211

Nid Storage

1740

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

27
       
Seasonal Comparison

Weather Forecast

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.