Number One Pond Reservoir Report

Last Updated: December 14, 2025

Number One Pond, located in Sanford, Maine, is a concrete gravity dam completed in 1912 primarily for flood risk reduction along the Mousam River.


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Summary

With a structural height of 14 feet and a length of 245 feet, the dam has a maximum storage capacity of 508 acre-feet and a normal storage capacity of 278 acre-feet, covering a surface area of 45 acres and draining an area of 41 square miles. The dam's spillway width is 185 feet, and it has been assessed to have a low hazard potential and fair condition as of the last inspection in October 2011.

Owned by the local government and regulated by the Maine Emergency Management Agency (MEMA), Number One Pond serves multiple purposes including flood risk reduction, recreation, and other uses. The dam has state permitting, inspection, and enforcement in place, ensuring its continued safety and functionality. The emergency action plan (EAP) for the dam was last revised in May 2018, but specific details on its compliance with guidelines and risk management measures are not available. Despite its age, Number One Pond Dam remains a vital infrastructure for water resource management in the area, contributing to the overall resilience of the community against flood events.

Year Completed

1912

Dam Length

245

Dam Height

14

River Or Stream

Mousam

Primary Dam Type

Concrete

Surface Area

45

Hydraulic Height

14

Drainage Area

41

Nid Storage

508

Structural Height

14

Hazard Potential

Low

Nid Height

14
       
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.