High hazard dams — those where failure would probably cause loss of human life — typically require regular inspections to identify safety deficiencies before they become emergencies. Most states mandate inspections every 1-5 years for high hazard dams.
Currently, 5,117 high hazard dams in the National Inventory of Dams show a last inspection date more than 5 years ago. While some of these may reflect data reporting delays rather than missed inspections, the gap between the recorded inspection date and today raises questions about ongoing monitoring.
This data comes from the NID and may not reflect inspections conducted but not yet reported to federal databases. For the most current inspection status, contact your state dam safety program.
Overdue Inspections by State
| State | Overdue High Hazard Dams | Oldest Inspection |
|---|---|---|
| Pennsylvania | 742 | 09/16/2014 |
| Texas | 728 | 06/01/1978 |
| Missouri | 547 | 04/04/1978 |
| Georgia | 489 | 12/01/1992 |
| Oklahoma | 289 | 01/01/1980 |
| Indiana | 255 | 01/01/1962 |
| Washington | 216 | 08/03/2001 |
| New Mexico | 192 | 06/15/2011 |
| Virginia | 181 | 02/14/1980 |
| Kansas | 129 | 10/12/1995 |
| North Carolina | 110 | 01/25/1978 |
| Wisconsin | 108 | 04/18/2005 |
| Ohio | 98 | 08/12/1983 |
| Oregon | 91 | 05/18/2018 |
| Michigan | 90 | 01/01/1901 |
| Montana | 88 | 03/31/2004 |
| Idaho | 62 | 04/04/2018 |
| New Hampshire | 48 | 08/08/2018 |
| Colorado | 47 | 06/08/2017 |
| West Virginia | 41 | 03/26/1992 |
| Arkansas | 41 | 01/01/2000 |
| Vermont | 39 | 01/01/1987 |
| Florida | 39 | 08/24/1996 |
| California | 39 | 09/19/2012 |
| Tennessee | 35 | 02/26/2018 |
| Massachusetts | 31 | 09/21/2015 |
| Connecticut | 30 | 11/04/1986 |
| Arizona | 29 | 11/09/2016 |
| South Dakota | 28 | 05/17/2012 |
| Mississippi | 26 | 01/25/2018 |
| Wyoming | 25 | 09/28/2016 |
| Puerto Rico | 25 | 04/05/2019 |
| North Dakota | 23 | 09/06/2016 |
| Alabama | 22 | 10/25/1978 |
| Alaska | 22 | 10/21/2010 |
| Utah | 16 | 07/07/2020 |
| New York | 12 | 07/29/1997 |
| Illinois | 12 | 07/14/2014 |
| Nebraska | 10 | 08/11/2020 |
| New Jersey | 9 | 07/24/2018 |
| Maine | 9 | 12/20/2016 |
| South Carolina | 8 | 07/20/2005 |
| Nevada | 7 | 09/14/2018 |
| Kentucky | 7 | 11/15/2017 |
| Rhode Island | 6 | 06/04/2010 |
| Minnesota | 5 | 02/23/2021 |
| Delaware | 4 | 10/16/2000 |
| Louisiana | 3 | 09/30/2020 |
| Iowa | 2 | 08/13/2019 |
| Maryland | 1 | 10/01/2019 |
| Hawaii | 1 | 08/21/2014 |
Largest Dams With Overdue Inspections
| Dam | State | Height (ft) | Last Inspection | Years Ago | Condition | EAP |
|---|---|---|---|---|---|---|
| Thompson Mtis | Idaho | 789 | 06/05/2019 | 7 | Fair | Yes |
| Glen Canyon Dam | Arizona | 710 | 09/22/2021 | 5 | Not assessed | Yes |
| Yankee Doodle Tailings Dam | Montana | 570 | 02/12/2020 | 6 | Satisfactory | Yes |
| Hungry Horse Dam | Montana | 564 | 06/24/2021 | 5 | Not assessed | Yes |
| Grand Coulee Dam | Washington | 550 | 09/17/2021 | 5 | Not assessed | Yes |
| North Block Tailings Impoundment Dam | Nevada | 520 | 05/13/2020 | 6 | Not assessed | Yes |
| Anderson Ranch Dam | Idaho | 456 | 07/27/2021 | 5 | Not assessed | Yes |
| Pine Flat Dam | California | 440 | 05/20/2021 | 5 | Not assessed | Yes |
| MUD Mountain Dam | Washington | 425 | 05/15/2021 | 5 | Not assessed | Yes |
| Harmar Refuse Bank | Pennsylvania | 410 | 04/02/2020 | 6 | Satisfactory | Yes |
| Navajo Dam | New Mexico | 402 | 09/24/2020 | 6 | Not assessed | Yes |
| Little Blue Run | Pennsylvania | 400 | 03/26/2021 | 5 | Fair | Yes |
| Jordanelle Dam | Utah | 391 | 07/09/2020 | 6 | Not assessed | Yes |
| Cumberland No. 1 Slurry Pond 1 | Pennsylvania | 380 | 10/30/2019 | 6 | Satisfactory | Yes |
| Cumberland No. 2 Slurry Pond | Pennsylvania | 370 | 11/18/2020 | 5 | Satisfactory | Yes |
| Theodore Roosevelt Dam | Arizona | 357 | 12/10/2020 | 5 | Not assessed | Yes |
| Warm Springs Dam | California | 356 | 09/27/2021 | 5 | Not assessed | Yes |
| Arrowrock Dam | Idaho | 350 | 05/05/2021 | 5 | Not assessed | Yes |
| Bailey Mine Area No. 3 Slurry | Pennsylvania | 337 | 08/03/2020 | 6 | Satisfactory | Yes |
| Ridgway Dam | Colorado | 330 | 06/10/2020 | 6 | Not assessed | Yes |
| Cerrillos Dam | Puerto Rico | 323 | 06/16/2021 | 5 | Satisfactory | Yes |
| Tieton Dam | Washington | 319 | 08/27/2020 | 6 | Not assessed | Yes |
| Bailey Mine Slurry Impoundment | Pennsylvania | 315 | 08/03/2020 | 6 | Satisfactory | Yes |
| Emerald No. 1 Main Valley Eastern | Pennsylvania | 310 | 11/18/2019 | 6 | Satisfactory | Yes |
| Cobre Main Tailings Dam | New Mexico | 310 | 07/01/2020 | 6 | Satisfactory | Yes |
| Bartlett Dam | Arizona | 309 | 03/04/2020 | 6 | Not assessed | Yes |
| Monticello Dam | California | 304 | 03/10/2020 | 6 | Not assessed | Yes |
| Mathies Mine Refuse Area Pond #2 | Pennsylvania | 300 | 04/01/2021 | 5 | Fair | Yes |
| Granby Dam | Colorado | 298 | 08/06/2020 | 6 | Not assessed | Yes |
| Mcphee Dam | Colorado | 295 | 09/23/2020 | 6 | Not assessed | Yes |
| Upper Stillwater Dam | Utah | 292 | 08/04/2021 | 5 | Not assessed | Yes |
| Questa Tailings Dam 1 | New Mexico | 280 | 09/16/2020 | 6 | Satisfactory | Yes |
| The Ohio Valley Coal Slurry Disposal Dam | Ohio | 275 | 09/25/2000 | 26 | Not assessed | Yes |
| Soldier Creek Dam | Utah | 272 | 06/08/2021 | 5 | Not assessed | Yes |
| Palisades Dam | Idaho | 270 | 05/11/2021 | 5 | Not assessed | Yes |
| Emerald No. 2 Main Valley Eastern | Pennsylvania | 270 | 11/18/2019 | 6 | Satisfactory | Yes |
| Blue River Dam | Oregon | 270 | 08/26/2021 | 5 | Not assessed | Yes |
| Conner Run Refuse Impoundment | West Virginia | 267 | 10/07/2013 | 13 | Satisfactory | Yes |
| Alcova Dam | Wyoming | 265 | 06/09/2021 | 5 | Not assessed | Yes |
| Culmback | Washington | 262 | 05/14/2021 | 5 | Satisfactory | Yes |
| Ririe Dam | Idaho | 253 | 05/04/2021 | 5 | Not assessed | Yes |
| John W. Flannagan Dam | Virginia | 250 | 09/02/2021 | 5 | Not assessed | Yes |
| Hughes Hollow Slurry Impoundment | Pennsylvania | 245 | 03/19/2021 | 5 | Satisfactory | Yes |
| Arthur R. Bowman Dam | Oregon | 245 | 06/22/2021 | 5 | Not assessed | Yes |
| Labelle Slurry Pond #3 | Pennsylvania | 245 | 12/10/2020 | 5 | Satisfactory | Yes |
| Pueblo Dam | Colorado | 245 | 04/10/2019 | 7 | Not assessed | Yes |
| Degray Dam - Saddle Dike | Arkansas | 243 | 07/22/2020 | 6 | Not assessed | Yes |
| Twitchell Dam | California | 241 | 08/24/2020 | 6 | Not assessed | Yes |
| Clifford D. Craig Memorial Dam | Virginia | 241 | 10/05/2021 | 5 | Fair | Yes |
| Deer Creek Dam | Utah | 240 | 07/08/2020 | 6 | Not assessed | Yes |
| Caonillas Dam | Puerto Rico | 235 | 09/04/2019 | 7 | Satisfactory | Yes |
| Masonry Dam | Washington | 230 | 10/01/2020 | 6 | Satisfactory | Yes |
| El Vado Dam | New Mexico | 230 | 07/28/2020 | 6 | Not assessed | Yes |
| Chino Mines Tailings Dam No. 7 | New Mexico | 230 | 06/30/2020 | 6 | Satisfactory | Yes |
| Canyon Ferry Dam | Montana | 225 | 09/08/2020 | 6 | Not assessed | Yes |
| Salmon Falls | Idaho | 224 | 05/15/2020 | 6 | Fair | Yes |
| Mormon Flat Dam | Arizona | 224 | 02/05/2020 | 6 | Not assessed | Yes |
| Boysen Dam | Wyoming | 220 | 08/25/2021 | 5 | Not assessed | Yes |
| Portugues Dam | Puerto Rico | 220 | 06/15/2021 | 5 | Satisfactory | Yes |
| Toa Vaca Dam | Puerto Rico | 215 | 04/16/2019 | 7 | Satisfactory | Yes |
| King Branch Slurry Dam | Kentucky | 214 | 04/08/2021 | 5 | Not assessed | Yes |
| Pathfinder Dam | Wyoming | 214 | 06/10/2021 | 5 | Not assessed | Yes |
| Questa Tailings Dam 4 | New Mexico | 212 | 09/16/2020 | 6 | Satisfactory | Yes |
| Starvation Dam | Utah | 210 | 09/08/2021 | 5 | Not assessed | Yes |
| Stewart Mountain Dam | Arizona | 210 | 05/25/2021 | 5 | Not assessed | Yes |
| New Hogan Dam | California | 210 | 08/09/2021 | 5 | Not assessed | Yes |
| Red Dog Tailings Main Dam | Alaska | 208 | 08/03/2020 | 6 | Satisfactory | Yes |
| Horseshoe Dam | Arizona | 202 | 05/26/2021 | 5 | Not assessed | Yes |
| Fletcher Tailings Dam | Missouri | 201 | 01/05/2009 | 17 | Unsatisfactory | Yes |
| Garzas Dam | Puerto Rico | 201 | 05/02/2019 | 7 | Unsatisfactory | Yes |
| Cornwall Tailings | Pennsylvania | 200 | 03/30/2021 | 5 | Fair | Yes |
| Barrick Goldstrike Tsf 3 Dam | Nevada | 200 | 05/13/2020 | 6 | Not assessed | Yes |
| Mojave River Dam - Saddle Dike 1 | California | 200 | 06/13/2018 | 8 | Not assessed | Yes |
| Stillhouse Hollow Dam - Dike | Texas | 200 | 05/13/2021 | 5 | Not assessed | Yes |
| Stillhouse Hollow Dam | Texas | 200 | 05/13/2021 | 5 | Not assessed | Yes |
| Paonia Dam | Colorado | 199 | 06/15/2021 | 5 | Not assessed | Yes |
| Gibson Dam | Montana | 199 | 09/02/2021 | 5 | Not assessed | Yes |
| Tenkiller Ferry Dam - Dike | Oklahoma | 197 | 05/08/2019 | 7 | Not assessed | Yes |
| Spring Creek Debris Dam | California | 196 | 03/09/2020 | 6 | Not assessed | Yes |
| Narrows Dam | Arkansas | 196 | 07/09/2020 | 6 | Not assessed | Yes |
| Angostura Dam | South Dakota | 193 | 08/26/2020 | 6 | Not assessed | Yes |
| Weisner Hollow Slurry | Pennsylvania | 192 | 10/24/2018 | 7 | Fair | Yes |
| Betsie Branch Refuse Impoundment | Kentucky | 191 | 03/03/2021 | 5 | Not assessed | Not Required |
| Dos Bocas Dam | Puerto Rico | 188 | 02/07/2020 | 6 | Satisfactory | Yes |
| Waterbury | Vermont | 187 | 08/03/2017 | 9 | Poor | Yes |
| Mine No 84 - Pond 6 Main | Pennsylvania | 185 | 12/15/2020 | 5 | Satisfactory | Yes |
| Meeks Cabin Dam | Wyoming | 185 | 07/16/2020 | 6 | Not assessed | Yes |
| Black Canyon Diversion Dam | Idaho | 183 | 04/01/2021 | 5 | Not assessed | Yes |
| Painted Rock Dam - Saddle Dike 1 | Arizona | 181 | 05/28/2021 | 5 | Not assessed | Yes |
| Hickory Log Reservoir Dam | Georgia | 180 | 01/12/2017 | 9 | Satisfactory | Yes |
| Caesar Creek Dam - Saddle Dike 2 | Ohio | 180 | 09/23/2020 | 6 | Not assessed | Yes |
| Round Valley South Dam | New Jersey | 178 | 10/01/2020 | 6 | Poor | Yes |
| Cambria Slurry Pond #4 | Pennsylvania | 178 | 07/10/2020 | 6 | Fair | Yes |
| Currant Creek Dam | Utah | 177 | 06/09/2021 | 5 | Not assessed | Yes |
| Swan Lake | Alaska | 174 | 09/30/2020 | 6 | Satisfactory | Yes |
| Mason Dam | Oregon | 173 | 09/10/2020 | 6 | Not assessed | Yes |
| Big Cliff Dam | Oregon | 172 | 05/10/2021 | 5 | Not assessed | Yes |
| Bill Evans Dam | New Mexico | 170 | 06/29/2020 | 6 | Satisfactory | Yes |
| Lucchetti Dam | Puerto Rico | 169 | 09/03/2020 | 6 | Satisfactory | Yes |
| Keyhole Dam | Wyoming | 168 | 08/27/2020 | 6 | Not assessed | Yes |