Old Falls Reservoir Report
Nearby: Estes Lake Dane Perkins
Last Updated: December 14, 2025
Old Falls, located in York, Maine, is a historic hydroelectric dam constructed in 1890 on the Mousam River.
°F
°F
mph
Wind
%
Humidity
Summary
The dam stands at 35.5 feet high with a hydraulic height of 31 feet, providing a storage capacity of 590 acre-feet and a drainage area of 100 square miles. Despite its age, the dam still serves as a significant source of hydroelectric power, with a normal storage capacity of 525 acre-feet and a surface area of 85 acres.
This privately owned dam has been regulated and inspected by the Maine Emergency Management Agency (MEMA), ensuring that it meets state permitting and enforcement standards. However, recent assessments have deemed its condition as poor, with a significant hazard potential, prompting the need for regular inspections and risk management measures. The dam's spillway width of 200 feet adds to its resilience in handling potential discharge events, showcasing its importance in water resource management and climate resilience efforts in the region.
Old Falls not only represents a historical landmark in Maine but also plays a crucial role in providing clean energy through hydroelectric power generation. With its unique stone dam structure and significant storage capacity, this dam serves as a vital component in the state's water infrastructure, highlighting the intersection of heritage conservation and sustainable energy production in the face of changing climate patterns. As efforts continue to maintain and improve its condition, Old Falls remains a symbol of innovation and resilience in the realm of water resource management.
Year Completed |
1890 |
Dam Length |
263 |
Dam Height |
35.5 |
River Or Stream |
Mousam |
Primary Dam Type |
Stone |
Surface Area |
85 |
Hydraulic Height |
31 |
Drainage Area |
100 |
Nid Storage |
590 |
Structural Height |
35.5 |
Hazard Potential |
Significant |
Nid Height |
36 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Mousam River Near West Kennebunk
|
44cfs |
Cocheco River Near Rochester
|
24cfs |
Isinglass R At Rochester Neck Rd
|
25cfs |
Oyster River Near Durham
|
3cfs |
Lamprey River Near Newmarket
|
42cfs |
Presumpscot River At Westbrook
|
-999999cfs |
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.
Old Falls
Main Street 550, Biddeford