Glen Road Reservoir Report

Last Updated: December 13, 2025

Glen Road, also known as Mascoma Dam No.3, is a private hydroelectric structure located in Lebanon, New Hampshire.


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Summary

Completed in 1988, this concrete gravity dam stands at a height of 16 feet and has a length of 175 feet, with a storage capacity of 10.2 acre-feet. The dam, situated on the Mascoma River, is regulated by the New Hampshire Department of Environmental Services Dam Bureau and inspected by the Federal Energy Regulatory Commission.

With a spillway width of 123 feet and a maximum discharge of 8970 cubic feet per second, Glen Road poses a significant hazard potential. Despite its moderate risk assessment rating, the condition assessment of the dam is currently listed as "Not Available." Emergency action plans have been prepared, but their adherence to guidelines and effectiveness in risk management remain undisclosed. The structure's location within a high-risk area underscores the importance of ongoing monitoring and maintenance to ensure its safety and resilience in the face of climate change impacts on water resources.

Year Completed

1988

Dam Length

175

Dam Height

16

River Or Stream

Mascoma River

Primary Dam Type

Concrete

Surface Area

2.2

Drainage Area

194

Nid Storage

10.2

Outlet Gates

Other Controlled - 1

Hazard Potential

Significant

Nid Height

16
       
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.