Lake Plymouth Dam is an earth dam located in Sussex County, New Jersey, built in 1951. It carries a Significant hazard potential classification and has a unsatisfactory condition assessment.
Dam profile
NID height · 14 ft14 ft tall and 495 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 Lake Plymouth Dam
The primary purpose of Lake Plymouth Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Lake Plymouth Comm. Assoc. Inc. (private). It impounds the Truot Brook near Newton.
The dam stands 14 feet tall and stretches 495 feet across, creates a reservoir covering 15 acres, has a maximum storage capacity of 99 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1951, the structure is well into its service life at over 50 years old.
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 unsatisfactory, indicating serious safety deficiencies exist that require immediate attention or remedial action. An emergency action plan is in place for this dam. The most recent inspection on record was 11/11/2023.
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Location
| State | New Jersey |
| County | Sussex |
| Nearest City | Newton |
| River/Stream | Truot Brook |
| Coordinates | 41.10962, -74.87685 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 14 ft |
| Dam Height | 14 ft |
| Dam Length | 495 ft |
| Year Completed | 1951 (75 years old) |
Storage & Hydraulics
| NID Storage | 99 acre-ft |
| Max Storage | 99 acre-ft |
| Normal Storage | 62 acre-ft |
| Surface Area | 15 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 268 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Lake Plymouth Comm. Assoc. Inc. |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Unsatisfactory |
| Last Inspection | 11/11/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NJ00818 |
| Federal ID | NJ00818 |
| More Info | State Dam Safety Program |