Minnewawa is a concrete dam located in Cheshire County, New Hampshire, built in 1923. It carries a High hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 63 ft63 ft tall and 265 ft long, taller than 95% of U.S. dams with a recorded height. Height is drawn to scale against a ten-story building, about 100 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Minnewawa
The primary purpose of Minnewawa is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by Marlborough Hydro Associates (private). It impounds the Minnewawa Brook near Marlborough.
The dam stands 63 feet tall and stretches 265 feet across, creates a reservoir covering 10 acres, has a maximum storage capacity of 155 acre-feet, and collects water from a drainage area of 23 square miles. Completed in 1923, the structure is over a century old.
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 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 06/14/2022.
At 63 feet, this dam is taller than 95% of all dams in the United States.
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 Hampshire 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 Hampshire |
| County | Cheshire |
| Nearest City | Marlborough |
| River/Stream | Minnewawa Brook |
| Coordinates | 42.91720, -72.17830 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 63 ft |
| Dam Height | 63 ft |
| Dam Length | 265 ft |
| Year Completed | 1923 (103 years old) |
Storage & Hydraulics
| NID Storage | 155 acre-ft |
| Max Storage | 155 acre-ft |
| Normal Storage | 155 acre-ft |
| Surface Area | 10 acres |
| Drainage Area | 23 sq mi |
| Max Discharge | 1,700 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Marlborough Hydro Associates |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/14/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NH00104 |
| Federal ID | NH00104 |
| More Info | State Dam Safety Program |