Squannacook River Dam
Squannacook River Dam is a concrete dam located in Middlesex County, Massachusetts. It carries a High hazard potential classification and has a fair condition assessment.
About Squannacook River Dam
The primary purpose of Squannacook River Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Groton Land Holdings, Inc.;town Of Groton (local government). It impounds the Squannacook River near Groton; Shirley.
The dam stands 18 feet tall and stretches 150 feet across, creates a reservoir covering 20 acres, has a maximum storage capacity of 110 acre-feet, and collects water from a drainage area of 1 square miles.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 05/05/2023.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Massachusetts dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Massachusetts |
| County | Middlesex |
| Nearest City | Groton; Shirley |
| River/Stream | Squannacook River |
| Coordinates | 42.60259, -71.62774 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 18 ft |
| Dam Length | 150 ft |
Storage & Hydraulics
| NID Storage | 110 acre-ft |
| Max Storage | 110 acre-ft |
| Normal Storage | 75 acre-ft |
| Surface Area | 20 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 1,400 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Groton Land Holdings, Inc.;Town of Groton |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 05/05/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MA00442 |
| Federal ID | MA00442 |
| More Info | State Dam Safety Program |