Upper Mystic Lake Dam
Upper Mystic Lake Dam is an earth dam located in Middlesex County, Massachusetts, built in 1860. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
About Upper Mystic Lake Dam
The primary purpose of Upper Mystic Lake Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Ma Department Of Conservation & Recreation (state). It impounds the Mystic River, D/s Of Aberjona River near Arlington.
The dam stands 16 feet tall and stretches 1,560 feet across, creates a reservoir covering 185 acres, has a maximum storage capacity of 2,800 acre-feet, and collects water from a drainage area of 27 square miles. Completed in 1860, the structure is one of the older dams in the region, with over a century and a half of service.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 02/24/2022.
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Location
| State | Massachusetts |
| County | Middlesex |
| Nearest City | Arlington |
| River/Stream | Mystic River, D/s Of Aberjona River |
| Coordinates | 42.43072, -71.14849 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 16 ft |
| Dam Length | 1,560 ft |
| Year Completed | 1860 (166 years old) |
Storage & Hydraulics
| NID Storage | 2,800 acre-ft |
| Max Storage | 2,800 acre-ft |
| Normal Storage | 1,300 acre-ft |
| Surface Area | 185 acres |
| Drainage Area | 27 sq mi |
| Max Discharge | 1,665 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | MA Department of Conservation & Recreation |
| Owner Type | State |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 02/24/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MA00769 |
| Federal ID | MA00769 |
| More Info | State Dam Safety Program |