Crystal Lake Dam is an earth dam located in Belknap County, New Hampshire, built in 1958. It carries a High hazard potential classification and has a poor condition assessment.
Dam profile
NID height · 16 ft16 ft tall and 188 ft long. 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 Crystal Lake Dam
The primary purpose of Crystal 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 Gilmanton.
The dam stands 16 feet tall and stretches 188 feet across, creates a reservoir covering 441 acres, has a maximum storage capacity of 3,500 acre-feet, and collects water from a drainage area of 27 square miles. Completed in 1958, 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 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 09/26/2019. That was 7 years ago, which is on the longer end for a high-hazard structure.
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 | Gilmanton |
| River/Stream | Suncook River |
| Coordinates | 43.42500, -71.30660 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 16 ft |
| Dam Height | 16 ft |
| Dam Length | 188 ft |
| Year Completed | 1958 (68 years old) |
Storage & Hydraulics
| NID Storage | 3,500 acre-ft |
| Max Storage | 3,500 acre-ft |
| Normal Storage | 1,400 acre-ft |
| Surface Area | 441 acres |
| Drainage Area | 27 sq mi |
| Max Discharge | 2,562 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Nh Des Water Division |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Poor |
| Last Inspection | 09/26/2019 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NH00018 |
| Federal ID | NH00018 |
| More Info | State Dam Safety Program |