Mattaceunk Reservoir Report
Nearby: Medway East Millinocket
Last Updated: December 21, 2025
Mattaceunk, also known as Weldon Dam, is a key hydroelectric structure located in Mattawamkeag, Maine, on the picturesque Penobscot River.
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Summary
Built in 1939, this dam stands 45 feet tall and stretches 1170 feet in length, with a storage capacity of 21,000 acre-feet and a surface area of 1700 acres. The dam serves multiple purposes, including flood risk reduction, water supply, navigation, and recreation, showcasing its importance in managing water resources in the region.
Managed by the Federal Energy Regulatory Commission, Mattaceunk has a high hazard potential and a very high risk assessment rating. Despite its age, the dam's condition assessment is currently not available, highlighting the need for regular inspections and maintenance to ensure its safety and efficiency. With a controlled spillway and a maximum discharge capacity of 168,300 cubic feet per second, Mattaceunk plays a crucial role in regulating water flow and supporting the local ecosystem, making it a significant structure for water resource and climate enthusiasts to study and monitor.
With its multi-arch core design and concrete, earth, and gravity dam types, Mattaceunk stands as a testament to engineering ingenuity and the intersection of human infrastructure with natural water systems. As climate change continues to impact water resources, understanding and managing structures like Mattaceunk will be essential in adapting to evolving environmental challenges and ensuring the sustainable use of water for generations to come.
Year Completed |
1939 |
Dam Length |
1170 |
Dam Height |
45 |
River Or Stream |
Penobscot River |
Surface Area |
1700 |
Drainage Area |
3308 |
Nid Storage |
21000 |
Outlet Gates |
Roller - 1 |
Hazard Potential |
High |
Foundations |
Rock |
Nid Height |
45 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
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.
Mattaceunk