Wiswall Dam is a concrete dam located in Strafford County, New Hampshire, built in 1911. It carries a Significant hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 22 ft22 ft tall and 400 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Wiswall Dam
The primary purpose of Wiswall Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Town of Durham (local government). It impounds the Lamprey River near Durham.
The dam stands 22 feet tall and stretches 400 feet across, creates a reservoir covering 27 acres, has a maximum storage capacity of 500 acre-feet, and collects water from a drainage area of 183 square miles. Completed in 1911, the structure is over a century old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 06/02/2021.
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Location
| State | New Hampshire |
| County | Strafford |
| Nearest City | Durham |
| River/Stream | Lamprey River |
| Coordinates | 43.10400, -70.96250 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 22 ft |
| Dam Height | 22 ft |
| Dam Length | 400 ft |
| Year Completed | 1911 (115 years old) |
Storage & Hydraulics
| NID Storage | 500 acre-ft |
| Max Storage | 500 acre-ft |
| Normal Storage | 134 acre-ft |
| Surface Area | 27 acres |
| Drainage Area | 183 sq mi |
| Max Discharge | 12,630 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Town of Durham |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 06/02/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NH00441 |
| Federal ID | NH00441 |
| More Info | State Dam Safety Program |