Cocassett Lake Dam is an earth dam located in Norfolk County, Massachusetts, built in 1813. It carries a Significant hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 16 ft16 ft tall and 350 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Cocassett Lake Dam
The primary purpose of Cocassett Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Cocassett Lake Association, Inc. (private). It impounds the Cocassett River near Foxborough.
The dam stands 16 feet tall and stretches 350 feet across, creates a reservoir covering 32 acres, has a maximum storage capacity of 215 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1813, 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 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 10/18/2022.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Massachusetts |
| County | Norfolk |
| Nearest City | Foxborough |
| River/Stream | Cocassett River |
| Coordinates | 42.05583, -71.25954 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 16 ft |
| Dam Length | 350 ft |
| Year Completed | 1813 (213 years old) |
Storage & Hydraulics
| NID Storage | 215 acre-ft |
| Max Storage | 215 acre-ft |
| Normal Storage | 180 acre-ft |
| Surface Area | 32 acres |
| Drainage Area | 2 sq mi |
| Max Discharge | 65 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Cocassett Lake Association, Inc. |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 10/18/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MA00817 |
| Federal ID | MA00817 |
| More Info | State Dam Safety Program |