Brooklyn Reservoir Report

Last Updated: December 15, 2025

Brooklyn, also known as Upper Groveton, is a private-owned hydroelectric dam located in Groveton, New Hampshire.


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Summary

Constructed in 1919, this dam on the Upper Ammonoosuc River serves multiple purposes, including hydroelectric power generation. With a height of 19 feet and a length of 275 feet, Brooklyn has a storage capacity of 240 acre-feet and a maximum discharge of 12,500 cubic feet per second.

Despite its age, Brooklyn has a low hazard potential and a moderate risk assessment rating. The dam is regulated by the New Hampshire Department of Environmental Services Dam Bureau and inspected by the Federal Energy Regulatory Commission. While the condition assessment is not available, the dam has a regular inspection frequency of 3 times a year to ensure its safety and integrity. The dam's spillway type is uncontrolled, with a width of 120 feet, serving as a safety measure in case of excessive water flow.

The dam's location in Coos County, New Hampshire, highlights its importance in water resource management and climate resilience efforts in the region. Brooklyn's role in hydroelectric power generation underscores its significance in sustainable energy production and environmental conservation. As water resource and climate enthusiasts, understanding the operational and regulatory aspects of dams like Brooklyn is essential for promoting responsible water management practices and mitigating potential risks associated with infrastructure like dams.

Year Completed

1919

Dam Length

275

Dam Height

19

River Or Stream

Upper Ammonoosuc River

Surface Area

26

Drainage Area

254

Nid Storage

240

Hazard Potential

Low

Nid Height

19
       
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.