Three Mile Reservoir Dam
Three Mile Reservoir Dam is a concrete dam located in Cheshire County, New Hampshire, built in 1986. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Three Mile Reservoir Dam
The primary purpose of Three Mile Reservoir Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by City Of Keene Dpw (local government). It impounds the Beaver Brook near Keene.
The dam stands 20 feet tall and stretches 292 feet across, creates a reservoir covering 8 acres, has a maximum storage capacity of 620 acre-feet, and collects water from a drainage area of 5 square miles. Completed in 1986, the structure is 40 years 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 06/23/2021.
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 | Keene |
| River/Stream | Beaver Brook |
| Coordinates | 42.97190, -72.25880 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 20 ft |
| Dam Height | 20 ft |
| Dam Length | 292 ft |
| Year Completed | 1986 (40 years old) |
Storage & Hydraulics
| NID Storage | 620 acre-ft |
| Max Storage | 620 acre-ft |
| Normal Storage | 250 acre-ft |
| Surface Area | 8 acres |
| Drainage Area | 5 sq mi |
| Max Discharge | 8,000 cfs |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | CITY OF KEENE DPW |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/23/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NH00736 |
| Federal ID | NH00736 |
| More Info | State Dam Safety Program |