Cocassett Lake Dam

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.

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.

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Significant HazardFair ConditionEmergency Action Plan: Yes

Location

StateMassachusetts
CountyNorfolk
Nearest CityFoxborough
River/StreamCocassett River
Coordinates42.05583, -71.25954

Physical Characteristics

Dam TypeEarth
NID Height16 ft
Dam Length350 ft
Year Completed1813 (213 years old)

Storage & Hydraulics

NID Storage215 acre-ft
Max Storage215 acre-ft
Normal Storage180 acre-ft
Surface Area32 acres
Drainage Area2 sq mi
Max Discharge65 cfs
Spillway TypeUncontrolled

Ownership & Safety

PurposeRecreation
OwnerCocassett Lake Association, Inc.
Owner TypePrivate
Hazard ClassificationSignificant
Condition AssessmentFair
Last Inspection10/18/2022
Emergency Action PlanYes

Identifiers

NID IDMA00817
Federal IDMA00817
More InfoState Dam Safety Program

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