South Mill Pond Dam Reservoir Report
Nearby: Upper Peverly Pond Dam Little Brook
Last Updated: December 23, 2025
South Mill Pond Dam, located in Portsmouth, New Hampshire, serves as a vital recreational resource in the community.
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Summary
Completed in 1983, this earth dam with a height of 13.5 feet and a length of 75 feet creates a storage capacity of 85 acre-feet, primarily used for recreational purposes. With a low hazard potential and satisfactory condition assessment, the dam is regulated by the NHDES Dam Bureau and undergoes regular inspections to ensure its safety and compliance with state regulations.
The dam's spillway, with a width of 12 feet, is of the uncontrolled type, allowing for the natural flow of water downstream to the TR Atlantic Ocean. Despite its moderate risk level, the dam has not required any significant modifications over the years and is equipped with emergency action plans to mitigate potential hazards. The surrounding area boasts a surface area of 9 acres and a drainage area of 0.23 square miles, making South Mill Pond Dam a valuable asset for both water resource management and climate enthusiasts seeking to explore the intersection of infrastructure and environmental conservation.
Year Completed |
1983 |
Dam Length |
75 |
Dam Height |
13.5 |
River Or Stream |
TR ATLANTIC OCEAN |
Primary Dam Type |
Earth |
Surface Area |
9 |
Drainage Area |
0.23 |
Nid Storage |
85 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
14 |
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.
South Mill Pond Dam
Little Harbor Loop Trail Portsmouth