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High-Hazard Dams Map: Dams That Could Cost Lives If They Failed

Where the country's high-hazard-potential dams are, and which are in poor or unsatisfactory condition.

The map shows 16,971 high-hazard dams. North Carolina has the most (1,678), then Texas (1,648) and Missouri (1,478).

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16,971high-hazard dams on the map
North Carolinahas the most (1,678)
51of the 50 states, DC and Puerto Rico have at least one
High-hazard dams on the Map the Block map of the United StatesOpen the live map →

🌊Condition (latest federal inspection)

Satisfactory5,303
Fair5,156
Not rated yet3,715
Poor2,294
Unsatisfactory503

🏗️States with the most high-hazard dams

North Carolina1,678
Texas1,648
Missouri1,478
California877
Pennsylvania788
South Carolina679
Georgia555
Colorado474
Virginia452
New York451

🔎About this data

High hazard means people downstream would probably die if the dam failed. It is about what lies below the dam, not how likely it is to fail. The condition rating covers repair: Satisfactory (no problems found), Fair (fine in normal weather; a rare flood or earthquake could cause one), Poor (a problem needs more study or repair), Unsatisfactory (a problem needs fixing right away). Many federal dams, such as Hoover Dam, do not publish a rating. Darker dots are in worse condition.

Source: U.S. Army Corps of Engineers, National Inventory of Dams (public map service, October 2026)

Coverage: Nationwide (50 states, DC, Puerto Rico and Guam): every dam rated high hazard potential (16,971)

How it was checked: All 16,971 dams the Army Corps counts as high hazard are on the map. 99.7% sit inside their own state; the rest are on state-line rivers. Spot checks match: Oroville Dam 770 ft, Hoover Dam 730 ft, and Michigan's Edenville Dam, which failed in 2020, is rated Unsatisfactory.

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Dataset dams_high_hazard · full file at /api/v1/bulk/dams_high_hazard.csv with your key · see the data terms.

💬Questions and answers

How many high-hazard dams are there in the United States?

The map shows 16,971 high-hazard dams. North Carolina has the most (1,678), then Texas (1,648) and Missouri (1,478).

How many high-hazard dams are in poor condition?

2,797 of the 16,971 high-hazard-potential dams on the map are rated Poor or Unsatisfactory in the National Inventory of Dams. High hazard means a failure would probably cost lives; it does not describe the dam's condition.

Where does this data come from?

U.S. Army Corps of Engineers, National Inventory of Dams (public map service, October 2026). Coverage: Nationwide (50 states, DC, Puerto Rico and Guam): every dam rated high hazard potential (16,971).

Is the map free to use?

Yes. Map the Block is free, with no ads or paywall. You may quote figures with credit to Map the Block (maptheblock.com); for bulk or commercial use there is a Data API.

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Numbers computed from the live map data on October 18, 2026. Free to quote with credit to “Map the Block (maptheblock.com)”; see reuse terms.