Gilman Falls Reservoir Report
Nearby: Milford Stillwater
Last Updated: December 22, 2025
Gilman Falls in Old Town, Maine, is a private hydroelectric dam on the Stillwater River completed in 1906.
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Summary
With a height of 8 feet and a length of 461.5 feet, the dam has a storage capacity of 2,250 acre-feet and serves the primary purpose of hydroelectric power generation. Additionally, the dam provides recreational opportunities in the area.
Managed by the Federal Energy Regulatory Commission, Gilman Falls has a low hazard potential and a moderate risk assessment level. The dam features an uncontrolled spillway with a width of 286 feet and two Tainter (radial) outlet gates. Despite not being state-regulated, the dam undergoes inspection every three years to ensure its structural integrity and safety.
Located in Penobscot County, Gilman Falls is a significant structure in the region's water resource management and climate adaptation efforts. Its historical significance, combined with its role in renewable energy production and recreational activities, makes Gilman Falls a noteworthy site for water resource and climate enthusiasts to explore and study.
Year Completed |
1906 |
Dam Length |
461.5 |
Dam Height |
8 |
River Or Stream |
Stillwater River |
Primary Dam Type |
Concrete |
Surface Area |
235 |
Drainage Area |
7600 |
Nid Storage |
2250 |
Outlet Gates |
Tainter (radial) - 2 |
Hazard Potential |
Low |
Nid Height |
8 |
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.
Gilman Falls