Souhegan River Site 10a Dam
Souhegan River Site 10a Dam is an earth dam located in Hillsborough, New Hampshire, built in 1966. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Souhegan River Site 10a Dam
The primary purpose of Souhegan River Site 10a 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 Nh Des Water Division (state). It impounds the Mill Brook near Wilton.
The dam stands 59 feet tall and stretches 1,281 feet across, creates a reservoir covering 7 acres, has a maximum storage capacity of 2,770 acre-feet, and collects water from a drainage area of 6 square miles. Completed in 1966, the structure is well into its service life at over 50 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 05/05/2021.
At 59 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 | Hillsborough |
| Nearest City | Wilton |
| River/Stream | Mill Brook |
| Coordinates | 42.85232, -71.80134 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 59 ft |
| Dam Height | 59 ft |
| Dam Length | 1,281 ft |
| Year Completed | 1966 (60 years old) |
Storage & Hydraulics
| NID Storage | 2,770 acre-ft |
| Max Storage | 2,770 acre-ft |
| Normal Storage | 49 acre-ft |
| Surface Area | 7 acres |
| Drainage Area | 6 sq mi |
| Max Discharge | 5,600 cfs |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | NH DES WATER DIVISION |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 05/05/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NH00264 |
| Federal ID | NH00264 |
| More Info | State Dam Safety Program |