Map of All 665 New Hampshire Dams
New Hampshire has 665 dams in the National Inventory of Dams — and 162 are classified as high hazard (24% of the state’s total), meaning failure would likely cause loss of life. 57 New Hampshire dams are both high-hazard and in poor or unsatisfactory condition.
Use the interactive New Hampshire dams map below to explore every dam in the state, color-coded by hazard level. Click any dam for its condition assessment, last inspection date, and Emergency Action Plan status. Or view the full US Dams interactive map to compare New Hampshire to every other state.
Hazard
Condition
Purpose
New Hampshire Dams by the Numbers
- 665 total dams in New Hampshire
- 162 high hazard — failure would likely cause loss of life
- 185 significant hazard
- 301 low hazard
- 152 in poor or unsatisfactory condition (147 poor, 5 unsatisfactory)
- 57 New Hampshire dams are both high-hazard AND in poor/unsatisfactory condition
Data source: US Army Corps of Engineers, National Inventory of Dams (NID).
The Tallest Dams in New Hampshire
The tallest dam in New Hampshire is Comerford at 170 feet, completed in 1930. The 10 tallest New Hampshire dams from the National Inventory of Dams:
| Dam | Height | Year | Primary Purpose | Condition | County |
|---|---|---|---|---|---|
| Comerford | 170 ft | 1930 | Hydroelectric | Satisfactory | Grafton |
| Moore | 149 ft | 1957 | Hydroelectric | Satisfactory | Grafton |
| Otter Brook Dam | 119 ft | 1958 | Flood Risk Reduction | Not Available | Cheshire |
| Franklin Falls Dam | 116 ft | 1943 | Flood Risk Reduction | Not Available | Merrimack |
| Everett Dam | 115 ft | 1961 | Flood Risk Reduction | Not Available | Hillsborough |
| Murphy Dam | 106 ft | 1938 | Recreation | Not Rated | Coos |
| Whitewater Brook Dam | 95 ft | 1968 | Water Supply | Fair | Sullivan |
| Surry Mountain Dam | 83 ft | 1941 | Flood Risk Reduction | Not Available | Cheshire |
| Ayers Island | 80 ft | 1924 | Hydroelectric | Satisfactory | Grafton |
| Souhegan River Site 26 Dam | 79 ft | 1965 | Flood Risk Reduction | Fair | Hillsborough |
High-Hazard New Hampshire Dams in Poor Condition
The most concerning dams are those classified as high-hazard that also carry a Poor or Unsatisfactory condition rating — 57 dams in New Hampshire. Notable examples:
- Baker River Site 6a Dam (68 ft, Grafton County) — Flood Risk Reduction, Poor condition
- Baker River Site 5 Dam (53 ft, Grafton County) — Flood Risk Reduction, Poor condition
- Jackman Reservoir Dam (43 ft, Hillsborough County) — Hydroelectric, Poor condition
- Lake Gloriette Dike (34 ft, Coos County) — Recreation, Poor condition
- Weare Reservoir Dam (34 ft, Hillsborough County) — Recreation, Poor condition
Filter the interactive US Dams map by hazard and condition to see all of them on one view.
Dam Safety in New Hampshire
Dam safety in New Hampshire is overseen by the state dam safety program, in coordination with federal regulators: the US Army Corps of Engineers, the Bureau of Reclamation (for federal water projects), the Tennessee Valley Authority where applicable, and the Federal Energy Regulatory Commission (FERC) for licensed hydropower dams. Emergency Action Plans are typically required for high-hazard dams under state regulations.
Frequently Asked Questions
How many dams are in New Hampshire?
New Hampshire has 665 dams in the National Inventory of Dams tracked by the US Army Corps of Engineers: 162 high hazard, 185 significant hazard, and 301 low hazard.
What is the tallest dam in New Hampshire?
The tallest dam in New Hampshire is Comerford at 170 feet, completed in 1930. It is primarily a hydroelectric structure.
How many New Hampshire dams are in poor condition?
152 New Hampshire dams are currently rated as being in Poor or Unsatisfactory condition. Of those, 57 are also classified as high-hazard — meaning failure would likely cause loss of life.
