While the total number of dams is increasing, the number of high hazard potential dams is also increasing at an alarming rate, now totaling 15,237.3 That represents an increase of more than 3,300 new high hazard potential dams since 2007. This increase is a result of new development below dams, which is dramatically increasing the consequences of failure and resulting in the reclassification of dams. This change in classification requires that significantly greater safety standards be met given the greater consequences of dam failure.
Number of Deficient Dams in United States by Repair Status
| year | # of deficient dams | # of High Hazard deficient dams | # of High Hazard repaired dams | # of High Hazard Dams needing repair |
|---|---|---|---|---|
| 2001 | 1,348 | 488 | 124 | 364 |
| 2002 | 1,536 | 646 | 163 | 483 |
| 2003 | 2,004 | 648 | 120 | 528 |
| 2004 | 3,000 | 979 | 100 | 879 |
| 2005 | 3,271 | 1,367 | 138 | 1,229 |
| 2006 | 3,346 | 1,308 | 139 | 1,169 |
| 2007 | 4,095 | 1,826 | 83 | 1,743 |
SOURCE Association of State Dam Safety Officials
