Upper Keswick Dam is an earth dam located in Ocean County, New Jersey, built in 1898. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 12 ft12 ft tall and 296 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 Upper Keswick Dam
The primary purpose of Upper Keswick Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by America's Keswick (private). It impounds the Wrangel Brook near Keswick Grove.
The dam stands 12 feet tall and stretches 296 feet across, creates a reservoir covering 16 acres, has a storage capacity of 54 acre-feet, and collects water from a drainage area of 8 square miles. Completed in 1898, the structure is over a century 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 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 03/19/2025.
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Location
| State | New Jersey |
| County | Ocean |
| Nearest City | Keswick Grove |
| River/Stream | Wrangel Brook |
| Coordinates | 39.94920, -74.34518 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 12 ft |
| Dam Height | 12 ft |
| Dam Length | 296 ft |
| Year Completed | 1898 (128 years old) |
Storage & Hydraulics
| NID Storage | 54 acre-ft |
| Normal Storage | 54 acre-ft |
| Surface Area | 16 acres |
| Drainage Area | 8 sq mi |
| Max Discharge | 486 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | America's Keswick |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 03/19/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NJ00047 |
| Federal ID | NJ00047 |
| More Info | State Dam Safety Program |