Cupsaw Lake Dam is an earth dam located in Passaic County, New Jersey, built in 1930. It carries a High hazard potential classification and has a poor condition assessment.
Dam profile
NID height · 35 ft35 ft tall and 430 ft long, taller than 80% of U.S. dams with a recorded height. 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 Cupsaw Lake Dam
The primary purpose of Cupsaw Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Cupsaw Lake Inprovement Association (private). It impounds the Cupsaw Brook.
The dam stands 35 feet tall and stretches 430 feet across, creates a reservoir covering 69 acres, has a storage capacity of 698 acre-feet, and collects water from a drainage area of 4 square miles. Completed in 1930, the structure is well-established, with more than 75 years of service.
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 poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. An emergency action plan is in place for this dam. The most recent inspection on record was 10/24/2023.
At 35 feet, this dam is taller than 80% of dams nationwide.
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 New Jersey 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 | New Jersey |
| County | Passaic |
| River/Stream | Cupsaw Brook |
| Coordinates | 41.11082, -74.25092 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 35 ft |
| Dam Height | 35 ft |
| Dam Length | 430 ft |
| Year Completed | 1930 (96 years old) |
Storage & Hydraulics
| NID Storage | 698 acre-ft |
| Normal Storage | 698 acre-ft |
| Surface Area | 69 acres |
| Drainage Area | 4 sq mi |
Ownership & Safety
| Purpose | Recreation |
| Owner | Cupsaw Lake Inprovement Association |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Poor |
| Last Inspection | 10/24/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NJ00194 |
| Federal ID | NJ00194 |
| More Info | State Dam Safety Program |