Stone Dam - Dike 1 Reservoir Report

Last Updated: December 21, 2025

Stone Dam - Dike 1, located in Millinocket, Maine, stands as a crucial structure along the West Branch Penobscot River.


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Summary

Built in 1900 for hydroelectric purposes, this earth dam spans 652 feet in length and reaches a height of 10 feet, providing a storage capacity of 8,100 acre-feet. Despite its low hazard potential, the dam's risk assessment is marked as high due to its age and the lack of available condition assessment data.

Managed by the Federal Energy Regulatory Commission, Stone Dam - Dike 1 serves multiple purposes including flood risk reduction, water supply, and recreation. With a surface area of 1,344 acres and a drainage area of 1,890 acres, the dam plays a significant role in regulating the flow of the river and supporting fish and wildlife habitats. However, the lack of recent inspections and condition assessments raises concerns about its long-term sustainability and safety.

As a key component of the region's water resource infrastructure, Stone Dam - Dike 1 requires ongoing monitoring and maintenance to ensure its continued functionality and safety. With a primary focus on hydroelectric power generation, the dam also contributes to navigation and recreation activities in the area. By prioritizing risk management measures and investing in regular inspections, stakeholders can safeguard this vital structure and preserve the ecological balance of the West Branch Penobscot River for future generations.

Year Completed

1900

Dam Length

652

Dam Height

10

River Or Stream

West Branch Penobscot River

Surface Area

1344

Drainage Area

1890

Nid Storage

8100

Hazard Potential

Low

Nid Height

10
       
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.