Medway Reservoir Report
Nearby: East Millinocket Dolby
Last Updated: December 21, 2025
Located in Medway, Maine, the Medway dam stands tall as a concrete hydroelectric structure along the West Branch Penobscot River.
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Summary
Built in 1922, this dam serves as a vital source of energy with a storage capacity of 1500 acre-feet and a maximum discharge of 18,700 cubic feet per second. Despite its age, the dam's condition assessment is listed as "Not Available" and its hazard potential is deemed low, making it a relatively stable structure in terms of risk management.
Managed by the Federal Energy Regulatory Commission, the Medway dam is not state-regulated and does not fall under state jurisdiction for permitting, inspection, or enforcement. With a spillway width of 343 feet and an uncontrolled spillway type, the dam has a moderate risk assessment rating of 3, indicating a need for cautious monitoring and risk management measures. The dam is privately owned and primarily serves the purpose of generating hydroelectric power, contributing to the region's energy needs.
In the event of an emergency, the Medway dam has an emergency action plan (EAP) in place, last revised in December 2018. Despite the lack of condition assessment data, the dam's relatively low hazard potential and moderate risk assessment suggest a reasonable level of safety and stability. With its historical significance and ongoing contribution to energy production, the Medway dam remains a key feature along the West Branch Penobscot River, showcasing the intersection of water resource management, climate resilience, and infrastructure sustainability in the region.
Year Completed |
1922 |
Dam Length |
448 |
Dam Height |
35.3 |
River Or Stream |
West Branch Penobscot River |
Primary Dam Type |
Concrete |
Surface Area |
101.5 |
Drainage Area |
2120 |
Nid Storage |
1500 |
Outlet Gates |
Slide (sluice gate) - 1 |
Hazard Potential |
Low |
Nid Height |
35 |
Seasonal Comparison
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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.
Medway
Dickey Moore Road 170, Medway
Hay Brook To Bridge Above Medway At State Route 157