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On This Page
- Assessment Summary
- Water Quality by Waterbody Type
- Causes of Impairment
- Probable Sources Contributing to Impairments
- Previously Impaired Waters Now Attaining All Uses
- Impaired Waters Listed by State
- Cumulative TMDLs by Pollutant
- Approved TMDLs by State
- Cumulative Number of TMDLs
- Status of Available Data Used in This Report
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Region 8 Summary of State Information
Depicted below are regional 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
Assessed Waters of Region 8
Incomplete state reported information may lead to discrepancies and/or missing information in these reports.
Description of this table| Size of Water | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rivers and Streams (Miles) |
Lakes, Reservoirs, and Ponds (Acres) |
||||||||||||||
| Good Waters | 130,227 | 700,498 | |||||||||||||
| Threatened Waters | 4,749 | 28,287 | |||||||||||||
| Impaired Waters | 36,133 | 1,253,973 | |||||||||||||
 |
|||||||||||||||
| Total Assessed Waters | 171,109 | 1,982,757 | |||||||||||||
| Total Waters | 628,573 | 3,280,427 | |||||||||||||
| Percent of Waters Assessed | 27.2 | 60.4 | |||||||||||||
Summary of Water Quality Assessments for Each Waterbody Type
Region 8
Water Quality Attainment in Assessed Rivers and Streams
Description of this table
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Description of this table
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Region 8
Designated Use Support in Assessed Rivers and Streams*
* Waters assessed for more than one designated use are included in multiple designated use groups below.
Description of this table| Designated Use Group | Miles Assessed | Percent Good | Percent Threatened | Percent Impaired |  % Good |
|
|---|---|---|---|---|---|---|
 % Threatened |
||||||
 % Impaired |
||||||
 |
Agricultural | 99,487 | 93.1 | .3 | 6.5 | |
 |
Fish, Shellfish, And Wildlife Protection And Propagation | 85,462 | 71.0 | .0 | 29.0 | |
 |
Recreation | 81,735 | 87.7 | .2 | 12.1 | |
 |
Public Water Supply | 58,329 | 91.4 | .1 | 8.5 | |
 |
Industrial | 14,015 | 90.2 | .0 | 9.8 | |
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Aquatic Life Harvesting | 7,889 | 61.1 | 2.8 | 36.1 | |
Region 8
Causes of Impairment in Assessed Rivers and Streams
Description of this table
| Cause of Impairment Group | Miles Threatened or Impaired |
|---|---|
| Metals (other than Mercury) | 14,530 |
| Habitat Alterations | 12,493 |
| Pathogens | 10,264 |
| Sediment | 9,597 |
| Nutrients | 7,510 |
| Flow Alteration(s) | 6,051 |
| Salinity/Total Dissolved Solids/Chlorides/Sulfates | 4,169 |
| Temperature | 3,384 |
| Turbidity | 2,304 |
| Mercury | 2,181 |
| Algal Growth | 1,783 |
| Organic Enrichment/Oxygen Depletion | 1,525 |
| Cause Unknown - Impaired Biota | 1,400 |
| pH/Acidity/Caustic Conditions | 816 |
| Ammonia | 480 |
| Cause Unknown | 319 |
| Toxic Inorganics | 195 |
| Radiation | 195 |
| Other Cause | 109 |
| Polychlorinated Biphenyls (PCBs) | 54 |
| Oil and Grease | 46 |
| Toxic Organics | 36 |
| Pesticides | 22 |
| Nuisance Exotic Species | 15 |
| Nuisance Native Species | 11 |
Region 8
Probable Sources of Impairments in Assessed Rivers and Streams
Description of this table
| Probable Source Group | Miles Threatened or Impaired |
|---|---|
| Agriculture | 24,047 |
| Unknown | 12,005 |
| Natural/Wildlife | 8,111 |
| Hydromodification | 7,868 |
| Habitat Alterations (Not Directly Related To Hydromodification) | 5,446 |
| Resource Extraction | 3,228 |
| Urban-Related Runoff/Stormwater | 2,330 |
| Municipal Dishcarges/Sewage | 1,923 |
| Silviculture (Forestry) | 1,838 |
| Construction | 1,655 |
| Aquaculture | 971 |
| Industrial | 848 |
| Other | 391 |
| Legacy/Historical Pollutants | 289 |
| Recreation And Tourism (Non-Boating) | 222 |
| Unspecified Nonpoint Source | 161 |
| Spills/Dumping | 149 |
| Atmospheric Deposition | 71 |
| Groundwater Loadings/Withdrawals | 27 |
Region 8
Water Quality Attainment in Assessed Lakes, Reservoirs, and Ponds
Description of this table
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Description of this table
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Region 8
Designated Use Support in Assessed Lakes, Reservoirs, and Ponds*
* Waters assessed for more than one designated use are included in multiple designated use groups below.
Description of this table| Designated Use Group | Acres Assessed | Percent Good | Percent Threatened | Percent Impaired | % Good |
|
|---|---|---|---|---|---|---|
| % Threatened |
||||||
| % Impaired |
||||||
|
Recreation | 911,100 | 64.5 | .0 | 35.5 | |
|
Agricultural | 904,667 | 82.7 | .0 | 17.3 | |
|
Fish, Shellfish, And Wildlife Protection And Propagation | 885,811 | 53.4 | .7 | 45.9 | |
|
Public Water Supply | 863,249 | 64.2 | .0 | 35.8 | |
|
Industrial | 312,638 | 97.6 | .0 | 2.4 | |
|
Aquatic Life Harvesting | 133,346 | 56.1 | 3.0 | 40.9 | |
Region 8
Causes of Impairment in Assessed Lakes, Reservoirs, and Ponds
Description of this table
| Cause of Impairment Group | Acres Threatened or Impaired |
|---|---|
| Mercury | 893,492 |
| Nutrients | 473,448 |
| Organic Enrichment/Oxygen Depletion | 437,788 |
| Temperature | 380,612 |
| Metals (other than Mercury) | 328,235 |
| Nuisance Native Species | 248,500 |
| Sediment | 147,592 |
| Polychlorinated Biphenyls (PCBs) | 129,357 |
| Salinity/Total Dissolved Solids/Chlorides/Sulfates | 123,517 |
| Flow Alteration(s) | 48,762 |
| Algal Growth | 48,316 |
| Ammonia | 35,710 |
| pH/Acidity/Caustic Conditions | 20,688 |
| Habitat Alterations | 8,465 |
| Pesticides | 3,800 |
| Cause Unknown | 3,781 |
| Turbidity | 3,168 |
| Pathogens | 1,516 |
| Other Cause | 80 |
| Toxic Organics | 78 |
Region 8
Probable Sources of Impairments in Assessed Lakes, Reservoirs, and Ponds
Description of this table
| Probable Source Group | Acres Threatened or Impaired |
|---|---|
| Unknown | 782,715 |
| Agriculture | 585,470 |
| Hydromodification | 550,298 |
| Municipal Dishcarges/Sewage | 399,030 |
| Atmospheric Deposition | 385,106 |
| Urban-Related Runoff/Stormwater | 346,227 |
| Resource Extraction | 295,818 |
| Legacy/Historical Pollutants | 250,500 |
| Natural/Wildlife | 201,994 |
| Construction | 140,860 |
| Silviculture (Forestry) | 139,012 |
| Habitat Alterations (Not Directly Related To Hydromodification) | 135,252 |
| Industrial | 99,715 |
| Unspecified Nonpoint Source | 57,120 |
| Recreation And Tourism (Non-Boating) | 18,722 |
| Spills/Dumping | 5,500 |
| Aquaculture | 4,490 |
| Other | 3,685 |
| Groundwater Loadings/Withdrawals | 78 |
| Land Application/Waste Sites/Tanks | 55 |
Region 8 Causes of Impairment
Description of this table
Region 8 Probable Sources Contributing to Impairments
Description of this table| NOTE: Click on a source of impairment (e.g. agriculture) to see the specific state-reported sources that are grouped to make up this category. | |||||||||||||||
| Probable Source Group | Size of Assessed Waters with Probable Sources of Impairments | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rivers and Streams (Miles) |
Lakes, Reservoirs, and Ponds (Acres) |
||||||||||||||
| Agriculture | 24,047 | 585,470 | |||||||||||||
| Aquaculture | 971 | 4,490 | |||||||||||||
| Atmospheric Deposition | 71 | 385,106 | |||||||||||||
| Construction | 1,655 | 140,860 | |||||||||||||
| Groundwater Loadings/Withdrawals | 27 | 78 | |||||||||||||
| Habitat Alterations (Not Directly Related To Hydromodification) | 5,446 | 135,252 | |||||||||||||
| Hydromodification | 7,868 | 550,298 | |||||||||||||
| Industrial | 848 | 99,715 | |||||||||||||
| Land Application/Waste Sites/Tanks | 55 | ||||||||||||||
| Legacy/Historical Pollutants | 289 | 250,500 | |||||||||||||
| Municipal Dishcarges/Sewage | 1,923 | 399,030 | |||||||||||||
| Natural/Wildlife | 8,111 | 201,994 | |||||||||||||
| Other | 391 | 3,685 | |||||||||||||
| Recreation And Tourism (Non-Boating) | 222 | 18,722 | |||||||||||||
| Resource Extraction | 3,228 | 295,818 | |||||||||||||
| Silviculture (Forestry) | 1,838 | 139,012 | |||||||||||||
| Spills/Dumping | 149 | 5,500 | |||||||||||||
| Unknown | 12,005 | 782,715 | |||||||||||||
| Unspecified Nonpoint Source | 161 | 57,120 | |||||||||||||
| Urban-Related Runoff/Stormwater | 2,330 | 346,227 | |||||||||||||
Region 8 Previously Impaired Waters Now Attaining All Uses
Description of this table| NOTE: Click on the underlined "Number of Waters Attaining" value for a detailed list of those waters now attaining all uses. | ||
| Cycle Attaining | Number of Waters Attaining | Number of Causes of Impairment Addressed |
|---|---|---|
| 2003 | 2 |
3 |
| 2004 | 5 |
5 |
| 2008 | 20 |
23 |
Region 8
Impaired Waters Listed By State
Description of this table
| State Name | Number of Waters on 303(d) List |
|---|---|
| Colorado | 200 |
| Montana | 677 |
| North Dakota | 247 |
| South Dakota | 168 |
| Utah | 118 |
| Wyoming | 106 |
Region 8 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 |
|---|---|---|
| Metals (other than Mercury) |  654 |
668 |
| Ammonia | 439 |
442 |
| Pathogens | 334 |
341 |
| Chlorine | 313 |
318 |
| Nutrients | 242 |
326 |
| Sediment | 225 |
280 |
| Organic Enrichment/Oxygen Depletion | 81 |
84 |
| Salinity/Total Dissolved Solids/Chlorides/Sulfates | 70 |
71 |
| Mercury | 36 |
38 |
| Toxic Inorganics | 36 |
36 |
| Temperature | 35 |
41 |
| Turbidity | 27 |
27 |
| Radiation | 21 |
22 |
| Toxic Organics | 12 |
12 |
| pH/Acidity/Caustic Conditions | 7 |
7 |
| Habitat Alterations | 5 |
5 |
| Polychlorinated Biphenyls (PCBs) | 2 |
2 |
| Noxious Aquatic Plants | 1 |
1 |
| Other Cause | 1 |
1 |
| Pesticides | 1 |
1 |
| Total Toxics | 1 |
1 |
Total: 2,543 TMDLs; 2,724 Causes of Impairment Addressed
Region 8 Approved TMDLs By State
This chart includes TMDLs since October 1, 1995.
Description of this table| State Name | Number of TMDLs |
|---|---|
| Colorado | 955 |
| Montana | 607 |
| North Dakota | 69 |
| South Dakota | 269 |
| Utah | 301 |
| Wyoming | 342 |
Region 8 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 |
|---|---|---|
| 1997 | 235 |
247 |
| 1998 | 99 |
105 |
| 1999 | 159 |
198 |
| 2000 | 86 |
93 |
| 2001 | 79 |
85 |
| 2002 | 224 |
232 |
| 2003 | 143 |
150 |
| 2004 | 355 |
381 |
| 2005 | 361 |
365 |
| 2006 | 246 |
249 |
| 2007 | 211 |
220 |
| 2008 | 168 |
214 |
| 2009 | 177 |
185 |
Total: 2,543 TMDLs; 2,724 Causes of Impairment Addressed
Status of Available Data Used in This Report
Description of this table| State Name | Assessed Waters Report Year | Impaired Waters Report Year |
|---|---|---|
| Colorado | 2008 | 2008 |
| Montana | 2006 | 2006 |
| North Dakota | 2008 | 2008 |
| South Dakota | 2008 | 2008 |
| Utah | 2006 | 2006 |
| Wyoming | 2008 | 2008 |