Hall Mountain Marsh Dam is a concrete dam located in Merrimack County, New Hampshire, built in 1945. It carries a Low hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 13 ft13 ft tall and 40 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 Hall Mountain Marsh Dam
The primary purpose of Hall Mountain Marsh Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Nh Fish and Game Department (state). It impounds the Bear Brook near Allenstown.
The dam stands 13 feet tall and stretches 40 feet across, creates a reservoir covering 21 acres, has a maximum storage capacity of 136 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1945, the structure is well-established, with more than 75 years of service.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected 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. The most recent inspection on record was 09/27/2018.
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Location
| State | New Hampshire |
| County | Merrimack |
| Nearest City | Allenstown |
| River/Stream | Bear Brook |
| Coordinates | 43.10330, -71.35750 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 13 ft |
| Dam Height | 13 ft |
| Dam Length | 40 ft |
| Year Completed | 1945 (81 years old) |
Storage & Hydraulics
| NID Storage | 136 acre-ft |
| Max Storage | 136 acre-ft |
| Normal Storage | 71 acre-ft |
| Surface Area | 21 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 553 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Nh Fish and Game Department |
| Owner Type | State |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 09/27/2018 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | NH00514 |
| Federal ID | NH00514 |
| More Info | State Dam Safety Program |