Montsweag Reservoir Report

Last Updated: December 19, 2025

Montsweag is a concrete dam located in Woolwich, Maine, along the Montsweag Brook (Upper).


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Summary

Completed in 1941, this structure stands at 18 feet in height and has a hydraulic height of 14 feet. With a storage capacity of 196 acre-feet, it serves as a vital water resource in the region. The dam's primary purpose is categorized as "Other," with a low hazard potential and a condition assessment that is currently not rated.

Owned and regulated by the local government, Montsweag Dam is subject to state jurisdiction and oversight by the Maine Emergency Management Agency (MEMA). It is equipped with a spillway width of 52 feet and has a normal storage capacity of 150 acre-feet. Despite not being rated for condition assessment, the dam is inspected annually, with the most recent inspection conducted in May 2020. With its strategic location and vital role in water management, Montsweag Dam plays a crucial role in the climate resilience and water resource management of the area, making it an important site for water resource and climate enthusiasts to monitor and study.

Year Completed

1941

Dam Length

245

Dam Height

18

River Or Stream

Montsweag Brook (Upper)

Primary Dam Type

Concrete

Surface Area

18

Hydraulic Height

14

Nid Storage

196

Structural Height

18

Hazard Potential

Low

Nid Height

18
       
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.