Long Pond Reservoir Report
Nearby: Folsom Pond Mattanawcook Pond
Last Updated: December 21, 2025
Long Pond, located in Penobscot, Maine, is a privately-owned reservoir that serves the primary purpose of flood risk reduction.
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Summary
Built in 1915, this earth dam stands at a height of 12 feet and has a hydraulic height of 8 feet, with a length of 150 feet. With a storage capacity of 1794 acre-feet and a normal storage level of 1410 acre-feet, Long Pond covers a surface area of 506 acres and drains an area of 8 square miles through the Mattanawcook Stream.
Despite being classified as a low hazard potential dam, Long Pond is state regulated and subject to regular inspection, permitting, and enforcement by the Maine Emergency Management Agency. The last inspection of the dam was conducted in November 2007, with a condition assessment of "Not Rated". The reservoir has not been modified in recent years and does not have a designated Emergency Action Plan, but it meets state guidelines for dam safety.
Water resource and climate enthusiasts interested in Long Pond can appreciate its historical significance as a flood control structure in the region. The dam contributes to the management of water levels and mitigates flood risks along the Mattanawcook Stream, showcasing the intersection of human infrastructure with natural water systems in Maine. Further monitoring and assessment of the dam's condition and emergency preparedness may be necessary to ensure the continued safety and functionality of Long Pond for both water resource management and environmental conservation purposes.
Year Completed |
1915 |
Dam Length |
150 |
Dam Height |
12 |
River Or Stream |
Mattanawcook Stream |
Primary Dam Type |
Earth |
Surface Area |
506 |
Hydraulic Height |
8 |
Drainage Area |
8 |
Nid Storage |
1794 |
Structural Height |
12 |
Hazard Potential |
Low |
Nid Height |
12 |
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.
Long Pond
Folsom Pond Road 500, Lincoln