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National Summary of
Impaired Waters and TMDL Information

Map of the United States

Depicted below are national summary tables and charts for available water quality data reported by the States to EPA under Section 305(b) and 303(d) of the Clean Water Act.

This report displays the most current available reporting year data.
Check the Status of Available Data for more information.


Frequent Questions


Impaired Waters Listed By State

Description of this table
State Name Number of Waters on 303(d) List
Alabama color.gif 200
Alaska color.gif 32
American Samoa color.gif 42
Arizona color.gif 84
Arkansas color.gif 224
California color.gif 691
Colorado color.gif 198
Connecticut color.gif 408
Delaware color.gif 101
District Of Columbia color.gif 27
Florida color.gif 827
Georgia color.gif 281
Guam color.gif 54
Hawaii color.gif 311
Idaho color.gif 1,057
Illinois color.gif 1,058
Indiana color.gif 1,836
Iowa color.gif 278
Kansas color.gif 1,333
Kentucky color.gif 1,089
Louisiana color.gif 250
Maine color.gif 206
Maryland color.gif 501
Massachusetts color.gif 837
Michigan color.gif 2,352
Minnesota color.gif 1,144
Mississippi color.gif 197
Missouri color.gif 204
Montana color.gif 677
N. Mariana Islands color.gif 71
Nebraska color.gif 177
Nevada color.gif 129
New Hampshire color.gif 5,211
New Jersey color.gif 745
New Mexico color.gif 187
New York color.gif 491
North Carolina color.gif 902
North Dakota color.gif 247
Ohio color.gif 267
Oklahoma color.gif 743
Oregon color.gif 1,397
Pennsylvania color.gif 6,957
Puerto Rico color.gif 166
Rhode Island color.gif 141
South Carolina color.gif 1,060
South Dakota color.gif 168
Tennessee color.gif 900
Texas color.gif 651
Utah color.gif 118
Vermont color.gif 131
Virgin Islands color.gif 77
Virginia color.gif 2,534
Washington color.gif 2,419
West Virginia color.gif 981
Wisconsin color.gif 593
Wyoming color.gif 106

Total: 44,068 impaired waters


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Causes of Impairment for 303(d) Listed Waters

Description of this table
NOTE: Click on a cause of impairment (e.g. pathogens) to see the specific state-reported causes that are grouped to make up this category. Click on the "Number of Causes of Impairment Reported" to see a list of waters with that cause of impairment.
Cause of Impairment Group Name Number of Causes of Impairment Reported
Pathogens color.gif 10,654
Mercury color.gif 8,874
Metals (other than Mercury) color.gif 7,498
Nutrients color.gif 6,825
Organic Enrichment/Oxygen Depletion color.gif 6,400
Sediment color.gif 6,292
Polychlorinated Biphenyls (PCBs) color.gif 6,206
pH/Acidity/Caustic Conditions color.gif 3,809
Cause Unknown - Impaired Biota color.gif 3,266
Turbidity color.gif 3,039
Temperature color.gif 3,011
Pesticides color.gif 1,798
Salinity/Total Dissolved Solids/Chlorides/Sulfates color.gif 1,732
Cause Unknown color.gif 1,259
Noxious Aquatic Plants color.gif 981
Habitat Alterations color.gif 702
Dioxins color.gif 542
Algal Growth color.gif 539
Toxic Organics color.gif 459
Ammonia color.gif 356
Toxic Inorganics color.gif 342
Total Toxics color.gif 318
Other Cause color.gif 222
Oil and Grease color.gif 155
Taste, Color and Odor color.gif 114
Flow Alteration(s) color.gif 109
Trash color.gif 57
Fish Consumption Advisory color.gif 56
Radiation color.gif 44
Chlorine color.gif 34
Nuisance Exotic Species color.gif 29
Cause Unknown - Fish Kills color.gif 12
Nuisance Native Species color.gif 5

Total: 75,739 Causes of Impairment

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National Cumulative TMDLs by Pollutant

This chart includes TMDLs since October 1, 1995.

Description of this table
NOTE: Click on the underlined "Pollutant Group" value to see a detailed list of pollutants. Click on the underlined "Number of TMDLs" value to see a listing of those TMDLs for the pollutant Group.
Pollutant Group Number of TMDLs Number of Causes of
Impairment Addressed
Pathogens color.gif 7,795 8,024
Metals (other than Mercury) color.gif 7,064 7,204
Mercury color.gif 6,793 6,825
Nutrients color.gif 4,454 5,315
Sediment color.gif 3,413 3,941
Organic Enrichment/Oxygen Depletion color.gif 1,811 1,884
pH/Acidity/Caustic Conditions color.gif 1,634 1,669
Temperature color.gif 1,550 1,557
Salinity/Total Dissolved Solids/Chlorides/Sulfates color.gif 1,516 1,557
Ammonia color.gif 1,073 1,135
Pesticides color.gif 998 1,058
Turbidity color.gif 917 1,043
Polychlorinated Biphenyls (PCBs) color.gif 358 372
Chlorine color.gif 336 341
Other Cause color.gif 208 225
Toxic Inorganics color.gif 189 189
Cause Unknown - Impaired Biota color.gif 169 173
Toxic Organics color.gif 126 127
Total Toxics color.gif 99 107
Habitat Alterations color.gif 83 84
Algal Growth color.gif 65 69
Trash color.gif 65 68
Dioxins color.gif 24 25
Noxious Aquatic Plants color.gif 21 22
Radiation color.gif 21 22
Oil and Grease color.gif 12 13
Cause Unknown color.gif 5 5
Fish Consumption Advisory color.gif 2 2
Nuisance Exotic Species color.gif 2 2

Total: 40,803 TMDLs; 43,058 Causes of Impairment Addressed

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Approved TMDLs By State

This chart includes TMDLs since October 1, 1995.

Description of this table
NOTE: Click on the state name to see a state report. Click on the Number of TMDLs to see a detailed list of the TMDLs.
State Name Number of TMDLs
Alabama color.gif 265
Alaska color.gif 44
American Samoa color.gif 2
Arizona color.gif 69
Arkansas color.gif 232
California color.gif 981
Colorado color.gif 958
Connecticut color.gif 118
Delaware color.gif 558
District Of Columbia color.gif 360
Florida color.gif 653
Georgia color.gif 1,595
Guam color.gif 1
Hawaii color.gif 53
Idaho color.gif 1,611
Illinois color.gif 303
Indiana color.gif 768
Iowa color.gif 136
Kansas color.gif 2,727
Kentucky color.gif 125
Louisiana color.gif 665
Maine color.gif 292
Maryland color.gif 615
Massachusetts color.gif 426
Michigan color.gif 160
Minnesota color.gif 1,173
Mississippi color.gif 1,387
Missouri color.gif 137
Montana color.gif 619
Nebraska color.gif 91
Nevada color.gif 58
New Hampshire color.gif 5,518
New Jersey color.gif 598
New Mexico color.gif 224
New York color.gif 638
North Carolina color.gif 145
North Dakota color.gif 69
Ohio color.gif 1,250
Oklahoma color.gif 223
Oregon color.gif 1,035
Pennsylvania color.gif 6,285
Puerto Rico color.gif 53
Rhode Island color.gif 111
South Carolina color.gif 425
South Dakota color.gif 269
Tennessee color.gif 1,039
Texas color.gif 154
Utah color.gif 301
Vermont color.gif 95
Virgin Islands color.gif 29
Virginia color.gif 993
Washington color.gif 1,167
West Virginia color.gif 2,562
Wisconsin color.gif 96
Wyoming color.gif 342

Total: 40,803 TMDLs


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National Cumulative Number of TMDLs

EPA Fiscal Year starts October 1 and ends September 30.


Description of this table
NOTE: Click on the underlined "Number of TMDLs Completed" value for a detailed list of the TMDLs for the fiscal year.
Fiscal Year Number of TMDLs Number of Causes of
Impairment Addressed
1996 color.gif 122 123
1997 color.gif 338 352
1998 color.gif 403 409
1999 color.gif 335 381
2000 color.gif 1,561 1,586
2001 color.gif 2,568 2,604
2002 color.gif 2,747 2,822
2003 color.gif 2,995 3,272
2004 color.gif 3,382 3,648
2005 color.gif 4,254 4,570
2006 color.gif 4,207 4,559
2007 color.gif 4,339 4,656
2008 color.gif 9,242 9,531
2009 color.gif 4,039 4,259
2010 color.gif 271 286

Total: 40,803 TMDLs; 43,058 Causes of Impairment Addressed

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Status of Available Data Used in This Report

Description of this table
State Name Assessed Waters Report Year Impaired Waters Report Year
Alabama 2008 2008
Alaska 2008 2008
American Samoa 2008 2008
Arizona 2008 2008
Arkansas 2008 2008
California 2004 2006
Colorado 2008 2008
Connecticut 2008 2008
Delaware 2006 2006
District Of Columbia 2008 2008
Florida 2002 2002
Georgia 2008 2008
Guam 2008 2008
Hawaii 2006 2006
Idaho 2008 2008
Illinois 2006 2006
Indiana 2008 2008
Iowa 2008 2006
Kansas 2008 2008
Kentucky 2008 2008
Louisiana 2008 2006
Maine 2008 2008
Maryland 2002 2006
Massachusetts 2006 2006
Michigan 2008 2008
Minnesota 2008 2008
Mississippi 2008 2008
Missouri 2008 2008
Montana 2006 2006
N. Mariana Islands 2008 2008
Nebraska 2008 2008
Nevada 2006 2004
New Hampshire 2006 2006
New Jersey 2008 2008
New Mexico 2008 2008
New York 2008 2008
North Carolina 2006 2006
North Dakota 2008 2008
Ohio 2008 2008
Oklahoma 2008 2008
Oregon 2006 2006
Pennsylvania 2006 2004
Puerto Rico 2008 2008
Rhode Island 2008 2008
South Carolina 2008 2008
South Dakota 2008 2008
Tennessee 2008 2008
Texas 2008 2008
Utah 2006 2006
Vermont 2008 2008
Virgin Islands 2008 2008
Virginia 2008 2008
Washington 2008 2008
West Virginia 2008 2008
Wisconsin 2006 2006
Wyoming 2008 2008


TMDL Document Search


Full Text Search of TMDL Documents

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