Sunset Lake Dam
Sunset Lake Dam is a concrete dam located in Belknap County, New Hampshire, built in 1860. It carries a High hazard potential classification and has a poor condition assessment.
About Sunset Lake Dam
The primary purpose of Sunset Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Nh Des Water Division (state). It impounds the Suncook River near Alton.
The dam stands 17 feet tall and stretches 130 feet across, creates a reservoir covering 205 acres, has a maximum storage capacity of 1,860 acre-feet, and collects water from a drainage area of 6 square miles. Completed in 1860, the structure is one of the older dams in the region, with over a century and a half 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 05/04/2020.
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 | Belknap |
| Nearest City | Alton |
| River/Stream | Suncook River |
| Coordinates | 43.46550, -71.29830 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 17 ft |
| Dam Height | 17 ft |
| Dam Length | 130 ft |
| Year Completed | 1860 (166 years old) |
Storage & Hydraulics
| NID Storage | 1,860 acre-ft |
| Max Storage | 1,860 acre-ft |
| Normal Storage | 1,400 acre-ft |
| Surface Area | 205 acres |
| Drainage Area | 6 sq mi |
| Max Discharge | 1,390 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | NH DES WATER DIVISION |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Poor |
| Last Inspection | 05/04/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NH00010 |
| Federal ID | NH00010 |
| More Info | State Dam Safety Program |