Pine Island Pond Dam Reservoir Report
Last Updated: December 16, 2025
Pine Island Pond Dam, located in Manchester, New Hampshire, is a local government-owned structure built in 1936 for recreational purposes along Cohas Brook.
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Summary
Standing at 19 feet high and 150 feet long, the earth dam has a storage capacity of 401 acre-feet and covers a surface area of 54 acres, serving as a popular destination for water resource and climate enthusiasts. The dam is regulated by the NHDES Dam Bureau and undergoes regular inspections, with a low hazard potential and fair condition assessment.
With a maximum discharge of 5630 cubic feet per second and an uncontrolled spillway width of 75 feet, Pine Island Pond Dam poses a moderate risk level of 3 according to the risk assessment data. Despite its age, the dam continues to provide recreational opportunities for visitors while meeting state permitting and inspection requirements. The structure's location in the Hillsborough County of New Hampshire, with a drainage area of 70 square miles, highlights its significance in managing water resources and contributing to the local ecosystem's sustainability.
Year Completed |
1936 |
Dam Length |
150 |
Dam Height |
19 |
River Or Stream |
COHAS BROOK |
Primary Dam Type |
Earth |
Surface Area |
54 |
Drainage Area |
70 |
Nid Storage |
401 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
19 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Pine Island Pond Dam
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