Map of All 830 New Jersey Dams
New Jersey has 830 dams in the National Inventory of Dams — and 232 are classified as high hazard (28% of the state’s total), meaning failure would likely cause loss of life. 56 New Jersey dams are both high-hazard and in poor or unsatisfactory condition.
Use the interactive New Jersey 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 Jersey to every other state.
Hazard
Condition
Purpose
New Jersey Dams by the Numbers
- 830 total dams in New Jersey
- 232 high hazard — failure would likely cause loss of life
- 332 significant hazard
- 266 low hazard
- 233 in poor or unsatisfactory condition (229 poor, 4 unsatisfactory)
- 56 New Jersey 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 Jersey
The tallest dam in New Jersey is Merrill Creek Main Dam at 280 feet, completed in 1988. The 10 tallest New Jersey dams from the National Inventory of Dams:
| Dam | Height | Year | Primary Purpose | Condition | County |
|---|---|---|---|---|---|
| Merrill Creek Main Dam | 280 ft | 1988 | Other | Satisfactory | Warren |
| Round Valley South Dam | 178 ft | 1961 | Water Supply | Poor | Hunterdon |
| Monksville Dam | 150 ft | 1986 | Water Supply | Satisfactory | Passaic |
| Round Valley North Dam | 135 ft | 1961 | Water Supply | Poor | Hunterdon |
| Boonton Dam | 120 ft | 1905 | Water Supply | Satisfactory | Morris |
| Raymond Dam | 103 ft | 1928 | Water Supply | Satisfactory | Passaic |
| Charlotteburg Dam | 102 ft | 1961 | Water Supply | Satisfactory | Morris |
| Spruce Run Reservoir Dam | 93 ft | 1964 | Water Supply | Poor | Hunterdon |
| Round Valley Dike | 80 ft | 1961 | Water Supply | Poor | Hunterdon |
| Clyde Potts Reservoir Dam | 80 ft | 1932 | Water Supply | Fair | Morris |
High-Hazard New Jersey Dams in Poor Condition
The most concerning dams are those classified as high-hazard that also carry a Poor or Unsatisfactory condition rating — 56 dams in New Jersey. Notable examples:
- Round Valley South Dam (178 ft, Hunterdon County) — Water Supply, Poor condition
- Round Valley North Dam (135 ft, Hunterdon County) — Water Supply, Poor condition
- Spruce Run Reservoir Dam (93 ft, Hunterdon County) — Water Supply, Poor condition
- Round Valley Dike (80 ft, Hunterdon County) — Water Supply, Poor condition
- Oak Ridge Reservoir Dam (60 ft, Passaic County) — Water Supply, Poor condition
Filter the interactive US Dams map by hazard and condition to see all of them on one view.
Dam Safety in New Jersey
Dam safety in New Jersey 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 Jersey?
New Jersey has 830 dams in the National Inventory of Dams tracked by the US Army Corps of Engineers: 232 high hazard, 332 significant hazard, and 266 low hazard.
What is the tallest dam in New Jersey?
The tallest dam in New Jersey is Merrill Creek Main Dam at 280 feet, completed in 1988. It is primarily a other structure.
How many New Jersey dams are in poor condition?
233 New Jersey dams are currently rated as being in Poor or Unsatisfactory condition. Of those, 56 are also classified as high-hazard — meaning failure would likely cause loss of life.
