Supply Pond Dam
Supply Pond Dam is an earth dam located in Hillsborough, New Hampshire, built in 1854. It carries a High hazard potential classification and has a fair condition assessment.
About Supply Pond Dam
The primary purpose of Supply Pond Dam is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by Pennichuck Water Works Inc (private). It impounds the Pennichuck Brook near Nashua.
The dam stands 28 feet tall and stretches 550 feet across, creates a reservoir covering 15 acres, has a maximum storage capacity of 414 acre-feet, and collects water from a drainage area of 26 square miles. Completed in 1854, 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 09/27/2022.
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 | Hillsborough |
| Nearest City | Nashua |
| River/Stream | Pennichuck Brook |
| Coordinates | 42.79143, -71.47443 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 28 ft |
| Dam Height | 28 ft |
| Dam Length | 550 ft |
| Year Completed | 1854 (172 years old) |
Storage & Hydraulics
| NID Storage | 414 acre-ft |
| Max Storage | 414 acre-ft |
| Normal Storage | 210 acre-ft |
| Surface Area | 15 acres |
| Drainage Area | 26 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | PENNICHUCK WATER WORKS INC |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 09/27/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NH00123 |
| Federal ID | NH00123 |
| More Info | State Dam Safety Program |