Dam Safety Statistics
Data and trends from 92,625 dams across 53 states in the National Inventory of Dams.
The United States has 92,625 dams recorded in the National Inventory of Dams (NID). Of these, 16,894 are classified as high hazard potential and 8,782 have a poor or unsatisfactory condition assessment. Data spans 53 states and territories.
By Hazard Potential
Classification based on potential consequences of dam failure.
By Condition Assessment
Physical state of dams based on inspection results.
Dams Built by Decade
Number of dams completed per decade based on NID records.
Top States by Dam Count
States with the most dams in the National Inventory.
Dams by Primary Purpose
Distribution of dams by their intended primary function.
Dam Count by State
Top 20 states ranked by total number of dams.
| # | State | Dams | High Hazard |
|---|---|---|---|
| 1 | Texas | 7,402 | 1,607 |
| 2 | Kansas | 6,490 | 328 |
| 3 | Mississippi | 6,092 | 349 |
| 4 | Georgia | 5,412 | 541 |
| 5 | Missouri | 5,385 | 1,478 |
| 6 | Oklahoma | 5,010 | 445 |
| 7 | Iowa | 4,128 | 95 |
| 8 | North Carolina | 3,642 | 1,652 |
| 9 | Montana | 3,029 | 214 |
| 10 | Nebraska | 2,961 | 160 |
| 11 | Virginia | 2,711 | 440 |
| 12 | South Dakota | 2,549 | 93 |
| 13 | South Carolina | 2,440 | 674 |
| 14 | Alabama | 2,266 | 228 |
| 15 | Colorado | 1,984 | 472 |
| 16 | New York | 1,939 | 450 |
| 17 | Illinois | 1,633 | 252 |
| 18 | California | 1,534 | 875 |
| 19 | Wyoming | 1,498 | 102 |
| 20 | Pennsylvania | 1,492 | 788 |
About This Data
All data comes from the U.S. Army Corps of Engineers National Inventory of Dams (NID). The NID contains records for 92,625 dams across 53 states and territories. Data is updated periodically as inspections are completed and new dams are registered.
Hazard potential classifies dams based on what would happen if the dam fails — it measures consequences, not likelihood. Condition assessment reflects the dam's actual physical state based on engineering inspections. A dam can be High hazard (near a town) but in Satisfactory condition, or Low hazard (remote area) but in Poor condition.