Somersworth Reservoir Report
Nearby: Lower Great Falls Rollinsford
Last Updated: December 19, 2025
Somersworth, also known as Stone Dam, is a significant hydroelectric structure located on the Salmon Falls River in New Hampshire.
°F
°F
mph
Wind
%
Humidity
Summary
Built in 1929, this masonry gravity dam stands at a height of 16.5 feet and has a storage capacity of 377 acre-feet. With a spillway width of 287 feet, the dam serves multiple purposes including hydroelectric power generation, fire protection, and water supply for the surrounding area.
Managed by the New Hampshire Department of Environmental Services Dam Bureau and regulated by the Federal Energy Regulatory Commission, Somersworth dam plays a crucial role in water resource management and climate resilience efforts. With a moderate risk assessment rating, the dam is inspected biennially to ensure its structural integrity and safety. Despite its age, the dam continues to provide valuable services to the community and support the conservation of the Salmon Falls River ecosystem.
Located in Strafford County, Somersworth dam is a key feature in the region's water infrastructure, contributing to the sustainable use of water resources and the preservation of aquatic habitats. As climate change impacts become more pronounced, the effective management of dams like Somersworth will be essential in mitigating risks and ensuring reliable access to clean water and renewable energy sources. As a symbol of human ingenuity and environmental stewardship, Somersworth dam represents a harmonious balance between nature and technology in the face of evolving climate challenges.
Year Completed |
1929 |
Dam Length |
400 |
Dam Height |
16.5 |
River Or Stream |
Salmon Falls River |
Surface Area |
55 |
Drainage Area |
218 |
Nid Storage |
377 |
Hazard Potential |
Significant |
Nid Height |
17 |
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.
Somersworth
Willand Pond boat launch