Washburn Mill Dam Reservoir Report
Last Updated: December 9, 2025
The Washburn Mill Dam, also known as the Henriette Jackson Dam, is a private-owned structure located in Colebrook, New Hampshire.
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Summary
It is regulated by the NHDES DAM BUREAU and serves multiple purposes, including fire protection and maintaining a stock or small fish pond. The dam is primarily made of earth and has a height of 25 feet and a length of 400 feet, with a storage capacity of 22.7 acre-feet.
Situated on the Mohawk River, the Washburn Mill Dam plays a crucial role in the local ecosystem and water resource management. With a maximum discharge capacity of 7331 cubic feet per second and a spillway width of 52 feet, the dam helps regulate water flow and prevent flooding in the area. Despite its moderate hazard potential and undetermined condition assessment, the dam is inspected regularly to ensure its safety and functionality.
Overall, the Washburn Mill Dam stands as a significant infrastructure for fire protection, stock management, and aquatic habitat preservation in Coos County, New Hampshire. As an essential component of the local water resource system, the dam's management and maintenance are paramount in ensuring the safety and sustainability of the surrounding environment and communities in the face of changing climate conditions.
Dam Length |
400 |
Dam Height |
25 |
River Or Stream |
MOHAWK RIVER |
Primary Dam Type |
Earth |
Surface Area |
0.3 |
Drainage Area |
25 |
Nid Storage |
22.7 |
Hazard Potential |
Undetermined |
Foundations |
Unlisted/Unknown |
Nid Height |
25 |
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.
Washburn Mill Dam