Upper Mystic Lake Dam Reservoir Report
Nearby: South Reservoir Dam Wedge Pond Dam
Last Updated: December 19, 2025
The Upper Mystic Lake Dam in Arlington, Massachusetts, is a state-regulated structure managed by the Department of Conservation and Recreation.
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Summary
Completed in 2009, this earth dam stands at a height of 16 feet and serves primarily for flood risk reduction. Its reservoir has a storage capacity of 2800 acre-feet and covers a surface area of 0.01 square miles, with a drainage area of 27.6 square miles.
The dam's purpose extends to supporting fish and wildlife habitats, as well as providing recreation opportunities in the area. Its spillway type is uncontrolled, and the dam is classified as having a significant hazard potential, with a satisfactory condition assessment as of March 2017. The risk assessment for the dam is moderate, with an inspection frequency of every 5 years to ensure its continued safety and functionality.
Enthusiasts of water resources and climate will find the Upper Mystic Lake Dam to be an essential piece of infrastructure for managing flood risks in the Mystic River watershed. Its construction and operation are overseen by state authorities, showcasing a commitment to environmental stewardship and public safety. This dam plays a vital role in balancing the needs of flood protection, wildlife conservation, and recreational enjoyment in the region.
Year Completed |
2009 |
Dam Length |
550 |
Dam Height |
16 |
River Or Stream |
MYSTIC RIVER, D/S OF ABERJONA RIVER |
Primary Dam Type |
Earth |
Surface Area |
0.01 |
Hydraulic Height |
9.2 |
Drainage Area |
27.6 |
Nid Storage |
2800 |
Hazard Potential |
Significant |
Foundations |
Unlisted/Unknown |
Nid Height |
16 |
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.
Upper Mystic Lake Dam
Pond Lane Arlington