Sanborn Pond Grist Mill Dam is an earth dam located in Merrimack County, New Hampshire, built in 1830. It carries a High hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 16 ft16 ft tall and 265 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 Sanborn Pond Grist Mill Dam
Sanborn Pond Grist Mill Dam is a dam in Merrimack, New Hampshire. The dam is owned by Sanborn Mills Inc (private). It impounds the Sanborn Brook near Loudon.
The dam stands 16 feet tall and stretches 265 feet across, creates a reservoir covering 125 acres, has a maximum storage capacity of 1,055 acre-feet, and collects water from a drainage area of 4 square miles. Completed in 1830, 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 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 11/04/2021.
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 | Merrimack |
| Nearest City | Loudon |
| River/Stream | Sanborn Brook |
| Coordinates | 43.33392, -71.38480 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 16 ft |
| Dam Height | 16 ft |
| Dam Length | 265 ft |
| Year Completed | 1830 (196 years old) |
Storage & Hydraulics
| NID Storage | 1,055 acre-ft |
| Max Storage | 1,055 acre-ft |
| Normal Storage | 470 acre-ft |
| Surface Area | 125 acres |
| Drainage Area | 4 sq mi |
| Max Discharge | 645 cfs |
Ownership & Safety
| Purpose | Other |
| Owner | Sanborn Mills Inc |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 11/04/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NH00182 |
| Federal ID | NH00182 |
| More Info | State Dam Safety Program |