Vital Statistics, Facts and Images

National Statistics

  • The average age of the more than 90,000 dams in the United States is 57 years old.
  • The number of high-hazard potential dams was more than 15,500 in 2018. That is about 17 percent of the dams in the National Inventory of Dams.
  • To rehabilitate the nation's non-federal dams it would cost more than $65 billion.
  • To rehabilitate the most critical non-federal dams alone, it would cost more than $20 billion.
  • As of the end of Calendar Year 2017, 81% of state-regulated High-Hazard Potential dams have Emergency Action Plans (EAPs).


State Dam Safety Program Statistics

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Graph 1 - Total NID Dams by Hazard Classification
Graph 1
Graph 2 - Dam Ownership
Graph 2
Graph 3 - Dam Safety Total State Budget
Graph 3
Graph 4 - National Average Dam Safety Budget per Regulated Dam
Graph 4
Graph 5 - Total Staff (FTE)
Graph 5
Graph 6 - EAP Completion Percentage for State-Regulated High Hazard Potential Dams
Graph 6
Graph 7 - State-Regulated High Hazard Potential Dams with an EAP
Graph 7
Graph 8 - National Inspection Percentage of State-Regulated High Hazard Potential Dams
Graph 8
Graph 9 - State Regulated High Hazard Potential Dams Identified in Need of Remediation (blue bar) & Remediated (red bar)
Graph 9

States have permitting, inspection, and enforcement authority for 70% of the 90,580 dams listed in the 2016 National Inventory of Dams (NID). More state and national statistics are available from their website.

Some important statistics to note:

  • Most dams listed in the NID are classified as low-hazard potential (Graph 1).
  • The vast majority of US dams are privately owned (Graph 2).
  • Total budgets for state dam safety programs have rebounded somewhat from the 2008 economic downturn when many programs experienced cuts in funding as state budgets struggled in general (Graph 3) (Graph 4). Staffing did see an increase in 2017 (following a slight decrease in 2015), and it has remained relatively steady in recent years with an overall increasing trend since 1999 (Graph 5).

State by state statistics and information about state-specific dam regulators are available in the 2018 State Dam Safety Program Statistics and State Dam Safety Performance Reports, which can be accessed through our state map.



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Perfect to Imperfect Dam - Maintenance (YouTubeDownload)
Overtopping Failure (YouTubeDownload)
Piping Failure (YouTube, Download)
Slope Failure  (YoutubeDownload)
Hazard Creep (YouTubeDownload

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