Tailings Dams in the United States
1,157Total
248High Hazard
408Significant
Tailings dams contain waste material from mining operations — typically a slurry of finely ground rock left over after valuable minerals have been extracted. Unlike conventional dams that impound water, tailings dams hold back semi-solid waste that can contain heavy metals, acids, and other contaminants.
Tailings dam failures are among the most environmentally devastating dam incidents. The waste they contain can contaminate rivers and groundwater for decades. These structures require ongoing monitoring even after mines close, because the retained material remains hazardous indefinitely. Notable failures worldwide have driven increased scrutiny of tailings dam safety in the U.S.
Tailings Dams by State
| State | Count | High Hazard | Tallest (ft) |
|---|---|---|---|
| Florida | 430 | 10 | 149 |
| Ohio | 78 | 15 | 275 |
| West Virginia | 60 | 48 | 780 |
| Missouri | 59 | 55 | 205 |
| Minnesota | 57 | 5 | 250 |
| Nevada | 55 | 3 | 520 |
| Kentucky | 51 | 39 | 665 |
| Texas | 45 | 2 | 93 |
| Georgia | 44 | 6 | 110 |
| Washington | 26 | 4 | 285 |
| North Carolina | 25 | 12 | 135 |
| Utah | 22 | 1 | 270 |
| New Mexico | 20 | 6 | 310 |
| Wyoming | 19 | 1 | 85 |
| Illinois | 18 | 8 | 117 |
| Idaho | 17 | 4 | 789 |
| Maryland | 17 | 2 | 70 |
| Michigan | 14 | 2 | 163 |
| Pennsylvania | 14 | 2 | 200 |
| Arizona | 11 | 5 | 400 |
| Tennessee | 10 | 1 | 447 |
| Virginia | 10 | 1 | 300 |
| Colorado | 9 | 3 | 416 |
| Mississippi | 9 | 0 | 60 |
| California | 6 | 3 | 58 |
| Montana | 6 | 5 | 60 |
| South Carolina | 5 | 1 | 110 |
| Alaska | 4 | 1 | 208 |
| Alabama | 4 | 0 | 100 |
| Arkansas | 4 | 1 | 90 |
| Oklahoma | 3 | 0 | 30 |
| Vermont | 3 | 1 | 120 |
| Louisiana | 1 | 0 | 20 |
| South Dakota | 1 | 1 | 380 |