Merrimack Dam Reservoir Report
Nearby: Merrimack Waste Gate Rolling
Last Updated: December 17, 2025
Merrimack Dam, located in Lowell, Massachusetts, is a historic structure completed in 1847 primarily for hydroelectric power generation.
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Summary
It stands at a height of 20 feet, with a hydraulic height of 10 feet, and a dam length of 18 feet. The dam has a low hazard potential and a very high risk assessment rating, making it a critical piece of infrastructure in the area.
With a storage capacity of 4,500 acre-feet, Merrimack Dam serves multiple purposes including fire protection, flood risk reduction, navigation, and recreation. It is constructed as a masonry dam type with a controlled spillway width of 16 feet. Despite not being state-regulated, the Federal Energy Regulatory Commission oversees its inspections and operations, ensuring its safety and compliance with regulations.
The dam is associated with 15 structures and plays a vital role in managing water resources in the area. Its historic significance, combined with its multifaceted purposes and strategic location on the Merrimack Canal, makes Merrimack Dam an essential asset for water resource and climate enthusiasts to study and monitor.
Year Completed |
1847 |
Dam Length |
18 |
Dam Height |
8 |
River Or Stream |
Merrimack Canal |
Primary Dam Type |
Masonry |
Surface Area |
720 |
Hydraulic Height |
10 |
Nid Storage |
4500 |
Structural Height |
20 |
Hazard Potential |
Low |
Nid Height |
20 |
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.
Merrimack Dam
Billerica Street 5-65, Lowell