Shannon Lake Dam is an earth dam located in Carroll County, New Hampshire, built in 1930. It carries a Significant hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 20 ft20 ft tall and 300 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 Shannon Lake Dam
The primary purpose of Shannon Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Castle Preservation Society (private). It impounds the Shannon Brook near Moultonborough.
The dam stands 20 feet tall and stretches 300 feet across, creates a reservoir covering 4 acres, has a maximum storage capacity of 21 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1930, the structure is well-established, with more than 75 years of service.
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 04/21/2022.
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Location
| State | New Hampshire |
| County | Carroll |
| Nearest City | Moultonborough |
| River/Stream | Shannon Brook |
| Coordinates | 43.73220, -71.32250 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 20 ft |
| Dam Height | 20 ft |
| Dam Length | 300 ft |
| Year Completed | 1930 (96 years old) |
Storage & Hydraulics
| NID Storage | 21 acre-ft |
| Max Storage | 21 acre-ft |
| Normal Storage | 15 acre-ft |
| Surface Area | 4 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 3,195 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Castle Preservation Society |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 04/21/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NH00562 |
| Federal ID | NH00562 |
| More Info | State Dam Safety Program |