North Twin - Dike 2 Reservoir Report

Last Updated: December 23, 2025

North Twin - Dike 2 is a vital structure located in Millinocket, Maine, along the West Branch Penobscot River.


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Summary

Built in 1934 for hydroelectric purposes, this earth dam stands at a height of 11 feet and stretches 150 feet in length, with a storage capacity of 346,000 acre-feet. While not under state jurisdiction, it is regulated by the Federal Energy Regulatory Commission and inspected regularly for safety.

Despite its age, North Twin - Dike 2 continues to play a significant role in flood risk reduction, water supply, and recreation in the region. With a surface area of 17,790 acres and a drainage area of 1,877 acres, the dam serves as a key component in managing the water resources of the area. While it has a significant hazard potential, regular inspections and risk assessments help to ensure its continued safe operation.

For water resource and climate enthusiasts, North Twin - Dike 2 represents a historic and vital piece of infrastructure in Maine's landscape. As a key player in hydroelectric power generation and water management, the dam's role in supporting fish and wildlife habitat, recreation, and flood risk reduction cannot be understated. With its unique design and ongoing maintenance efforts, North Twin - Dike 2 stands as a testament to the importance of sustainable water resource management in the face of changing climate conditions.

Year Completed

1934

Dam Length

150

Dam Height

11

River Or Stream

West Branch Penobscot River

Surface Area

17790

Drainage Area

1877

Nid Storage

346000

Hazard Potential

Significant

Nid Height

11
       
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.