Map of All 1,491 Pennsylvania Dams
Pennsylvania has 1,491 dams in the National Inventory of Dams — and 788 are classified as high hazard (53% of the state’s total), meaning failure would likely cause loss of life. 145 Pennsylvania dams are both high-hazard and in poor or unsatisfactory condition.
Use the interactive Pennsylvania 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 Pennsylvania to every other state.
Hazard
Condition
Purpose
Pennsylvania Dams by the Numbers
- 1,491 total dams in Pennsylvania
- 788 high hazard — failure would likely cause loss of life
- 309 significant hazard
- 381 low hazard
- 215 in poor or unsatisfactory condition (195 poor, 20 unsatisfactory)
- 145 Pennsylvania 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 Pennsylvania
The tallest dam in Pennsylvania is Harmar Refuse Bank at 410 feet, completed in 1957. The 10 tallest Pennsylvania dams from the National Inventory of Dams:
| Dam | Height | Year | Primary Purpose | Condition | County |
|---|---|---|---|---|---|
| Harmar Refuse Bank | 410 ft | 1957 | Other | Satisfactory | Allegheny |
| Little Blue Run | 400 ft | 1977 | Other | Fair | Beaver |
| Cumberland No. 1 Slurry Pond 1 | 380 ft | 1984 | Other | Satisfactory | Greene |
| Cumberland No. 2 Slurry Pond | 370 ft | – | Other | Satisfactory | Greene |
| Bailey Mine Area No. 3 Slurry | 337 ft | 2014 | Other | Satisfactory | Greene |
| Bailey No. 8 Slurry Impoundment | 317 ft | – | Other | Not Rated | Greene |
| Bailey Mine Slurry Impoundment | 315 ft | 1984 | Other | Satisfactory | Greene |
| Emerald No. 1 Main Valley Eastern | 310 ft | – | Other | Satisfactory | Greene |
| Mathies Mine Refuse Area Pond #2 | 300 ft | 1982 | Other | Fair | Washington |
| Emerald No. 2 Main Valley Eastern | 270 ft | – | Other | Satisfactory | Greene |
High-Hazard Pennsylvania Dams in Poor Condition
The most concerning dams are those classified as high-hazard that also carry a Poor or Unsatisfactory condition rating — 145 dams in Pennsylvania. Notable examples:
- Little Pine Creek (113 ft, Lycoming County) — Flood Risk Reduction, Poor condition
- North Fork (105 ft, Somerset County) — Water Supply, Poor condition
- Dehart (105 ft, Dauphin County) — Water Supply, Poor condition
- Mill Run (100 ft, Blair County) — Water Supply, Poor condition
- Leavitt Branch (Pa-463) (90 ft, Monroe County) — Flood Risk Reduction, Poor condition
Filter the interactive US Dams map by hazard and condition to see all of them on one view.
Dam Safety in Pennsylvania
Dam safety in Pennsylvania 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 Pennsylvania?
Pennsylvania has 1,491 dams in the National Inventory of Dams tracked by the US Army Corps of Engineers: 788 high hazard, 309 significant hazard, and 381 low hazard.
What is the tallest dam in Pennsylvania?
The tallest dam in Pennsylvania is Harmar Refuse Bank at 410 feet, completed in 1957. It is primarily a other structure.
How many Pennsylvania dams are in poor condition?
215 Pennsylvania dams are currently rated as being in Poor or Unsatisfactory condition. Of those, 145 are also classified as high-hazard — meaning failure would likely cause loss of life.
