U.S. Dam Safety Data

Explore safety data for over 91,812 dams across the United States, sourced from the National Inventory of Dams (NID). View hazard classifications, condition assessments, and key statistics by state.

Total Dams

91,812

High Hazard

16,367

17.8% of all dams

Poor / Unsatisfactory

8,684

9.5% of all dams

Average Age

65 years

Understanding Hazard Classification

Hazard classification indicates the potential consequences of dam failure, not the likelihood of failure or the current condition of the dam.

High Hazard

Failure would likely cause loss of life

Significant Hazard

Failure could cause economic loss or disruption

Low Hazard

Failure would cause minimal damage

Browse Dams by State

StateTotal Dams
Alabama2,255
Alaska107
Arizona376
Arkansas1,263
California1,436
Colorado1,962
Connecticut1,225
Delaware83
Florida1,074
Georgia5,386
Guam1
Hawaii124
Idaho395
Illinois1,630
Indiana1,087
Iowa4,124
Kansas6,485
Kentucky1,065
Louisiana747
Maine582
Maryland425
Massachusetts1,291
Michigan1,020
Minnesota1,122
Mississippi6,089
Missouri5,380
Montana2,990
Nebraska2,954
Nevada507
New Hampshire664
New Jersey830
New Mexico411
New York1,871
North Carolina3,622
North Dakota948
Ohio1,377
Oklahoma4,984
Oregon856
Pennsylvania1,481
Puerto Rico36
Rhode Island234
South Carolina2,400
South Dakota2,541
Tennessee1,204
Texas7,399
Utah867
Vermont363
Virginia2,702
Washington817
West Virginia562
Wisconsin968
Wyoming1,490

Dams by Primary Purpose

Recreation30,840
Flood Risk Reduction14,999
Fire Protection, Stock, Or Small Fish Pond12,011
Irrigation7,623
Other7,420
Unknown5,761
Water Supply5,165
Fish and Wildlife Pond3,194
Hydroelectric1,746
Tailings1,203

States with Most High Hazard Dams

#1North Carolina

1,638

high hazard (45.2%)

#2Texas

1,604

high hazard (21.7%)

#3Missouri

1,476

high hazard (27.4%)

#4California

821

high hazard (57.2%)

#5Pennsylvania

780

high hazard (52.7%)

#6South Carolina

645

high hazard (26.9%)

#7Georgia

524

high hazard (9.7%)

#8Colorado

451

high hazard (23%)

#9West Virginia

445

high hazard (79.2%)

#10Virginia

433

high hazard (16%)

Tallest Dams in the U.S.

DamStateHeight (ft)
Thompson MtisIdaho789
Chess Refuse Disposal Area No. 1West Virginia780
Delbarton Slurry ImpoundmentWest Virginia760
Hoover DamNevada730
Dworshak DamIdaho717
Glen Canyon DamArizona710
Abner Fork DamKentucky700
Sidney Slurry ImpoundmentKentucky665
Long Fork Slurry ImpoundmentKentucky665
Killarney Slurry ImpoundmentWest Virginia657

Largest Reservoir Storage

DamStateStorage (acre-ft)
Soo LocksMichigan277,540,000
Hoover DamNevada30,237,000
Garrison DamNorth Dakota26,000,000
Glen Canyon DamArizona25,025,826
Oahe DamSouth Dakota23,600,000
Fort Peck DamMontana19,100,000
Grand Coulee DamWashington9,715,346
Herbert Hoover Dike - CIZ BFlorida8,519,000
Acorn RidgeNorth Dakota7,173,400
Sam Rayburn DamTexas6,520,000

Data Source

Dam data is sourced from the National Inventory of Dams (NID), maintained by the U.S. Army Corps of Engineers. The NID is the most comprehensive database of dams in the United States. Data is updated periodically; the information shown here may not reflect the most current status of any individual dam.