Jackman Reservoir Dam Reservoir Report

Last Updated: December 18, 2025

Jackman Reservoir Dam, also known as Franklin Pierce Lake Dam, is a public utility-owned structure located in Hillsborough, New Hampshire.


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Summary

Completed in 1926, this earth dam stands at a height of 43 feet and has a length of 1870 feet, creating a storage capacity of 12,400 acre-feet on the NORTH BRANCH CONTOOCOOK RIVER. The primary purpose of the dam is hydroelectric power generation, making it a vital component of New Hampshire's energy infrastructure.

Managed by the NHDES DAM BUREAU, Jackman Reservoir Dam has a high hazard potential due to its location and storage capacity. Despite this, the dam is currently deemed to be in satisfactory condition following a recent assessment in October 2016. Regular inspections are conducted, with the last one taking place in June 2020, to ensure the safety and integrity of the structure. With a moderate risk level and a storage capacity of 8,360 acre-feet under normal conditions, the dam plays a crucial role in water resource management in the region.

The dam's uncontrolled spillway, with a width of 104 feet, allows for the safe release of excess water during periods of high flow. The surrounding area covers 486 acres, with a drainage area of 63 square miles. Jackman Reservoir Dam stands as a testament to the intersection of water resource management, climate resilience, and renewable energy generation, serving as a vital piece of infrastructure in New Hampshire's diverse and dynamic landscape.

Year Completed

1926

Dam Length

1870

Dam Height

43

River Or Stream

NORTH BRANCH CONTOOCOOK RIVER

Primary Dam Type

Earth

Surface Area

486

Drainage Area

63

Nid Storage

12400

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

43
       
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.