Gregg Falls Reservoir Report

Last Updated: December 17, 2025

Gregg Falls, also known as Glenn Lake Dam, is a captivating hydroelectric structure located in Pinardville, New Hampshire.


°F

°F

mph

Wind

%

Humidity

Summary

Built in 1917, this dam stands at a height of 66 feet and has a length of 1360 feet, with a storage capacity of 3650 acre-feet. Its primary purpose is hydroelectric power generation, while also serving for fire protection, stock, small fish pond, and recreation purposes.

Managed by the New Hampshire Department of Environmental Services Dam Bureau, Gregg Falls is regulated and inspected regularly to ensure its safety and compliance with state laws. With a high hazard potential due to its location on the Piscataquog River, the dam poses a moderate risk and is equipped with uncontrolled spillways and slide gates for water management. Despite its age, Gregg Falls continues to play a vital role in the local water resource management and contributes to the region's energy infrastructure.

As a significant landmark in Hillsborough County, Gregg Falls represents a blend of history, technology, and environmental stewardship. With its gravity, earth, and concrete construction, the dam symbolizes the intersection of human ingenuity and natural resources, showcasing the importance of sustainable water management practices. For water resource and climate enthusiasts, Gregg Falls serves as a reminder of the crucial role that infrastructure plays in shaping our relationship with the environment and the need for ongoing monitoring and maintenance to ensure its longevity and safety.

Year Completed

1917

Dam Length

1360

Dam Height

66

River Or Stream

Piscataquog River

Surface Area

138

Drainage Area

200

Nid Storage

3650

Outlet Gates

Slide (sluice gate) - 2

Hazard Potential

High

Nid Height

66
       
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.