Macallen Dam
Macallen Dam is a concrete dam located in Rockingham County, New Hampshire, built in 1887. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Macallen Dam
The primary purpose of Macallen 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 Newmarket (local government). It impounds the Lamprey River near Newmarket.
The dam stands 27 feet tall and stretches 150 feet across, creates a reservoir covering 120 acres, has a maximum storage capacity of 1,740 acre-feet, and collects water from a drainage area of 211 square miles. Completed in 1887, the structure is over a century old.
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 satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 08/02/2022.
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 | Rockingham |
| Nearest City | Newmarket |
| River/Stream | Lamprey River |
| Coordinates | 43.08110, -70.93470 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 27 ft |
| Dam Height | 27 ft |
| Dam Length | 150 ft |
| Year Completed | 1887 (139 years old) |
Storage & Hydraulics
| NID Storage | 1,740 acre-ft |
| Max Storage | 1,740 acre-ft |
| Normal Storage | 480 acre-ft |
| Surface Area | 120 acres |
| Drainage Area | 211 sq mi |
| Max Discharge | 10,930 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | TOWN OF NEWMARKET |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 08/02/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NH00365 |
| Federal ID | NH00365 |
| More Info | State Dam Safety Program |