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Idaho Assessment Summary for Reporting Year 2008

	Size of Water
	Rivers and Streams (Miles)	Lakes, Reservoirs, and Ponds (Acres)
Good Waters	26,021.5	2,781.0
Previously impaired waters       now attaining all uses
Threatened Waters	48.5
TMDL completed	48.5
TMDL alternative
Non-pollutant impairment
TMDL needed
Impaired Waters	34,175.1	220,463.3
TMDL completed	13,418.1	17,135.9
TMDL alternative
Non-pollutant impairment	450.2	950.1
TMDL needed	20,306.8	202,377.3
New TMDLs completed	438.0	.0
Remaining TMDLs needed	19,868.8	202,377.3
Total Assessed Waters	60,245.0	223,244.3
Total Waters	115,595.0	469,200.0
Percent of Waters Assessed	52.1	47.6

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Summary of Water Quality Assessments for Each Waterbody Type
for Reporting Year 2008

Idaho Assessed Waters
Summary of Water Quality Attainment for Rivers and Streams
Reporting Year 2008

Description of this table Assessed Status Miles Assessed 60,245.0 Unassessed 55,350.0 Total Miles 115,595.0

Description of this table Attainment Status Miles Good 26,021.5 Threatened 48.5 Impaired 34,175.1 Total Miles Assessed 60,245.0

Description of this table TMDL Development Status Miles All TMDLs completed 13,904.5 TMDL alternative .0 Non-pollutant impairment 450.2 TMDL needed 19,868.8 Total Threatened and Impaired 34,223.6

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Idaho Assessed Waters
Designated Use Support for Rivers and Streams
Reporting Year 2008*

* Waters assessed for more than one designated use are included in multiple designated use groups below.

Designated Use	Miles Assessed	Percent Good	Percent Threatened	Percent Impaired	% Good
					% Threatened
					% Impaired
Aesthetic	5,432.7	99.9	.0	.1
Agricultural Water Supply	7,284.4	96.8	.0	3.2
Cold Water Aquatic Life	59,110.3	44.6	.1	55.4
Domestic Water Supply	4,255.2	94.9	.0	5.1
Industrial Water Supply	6,908.0	100.0	.0	.0
Primary Contact Recreation	14,010.8	72.8	.0	27.2
Salmonid Spawning	29,123.8	55.6	.2	44.3
Seasonal Cold Water Aquatic Life	13.5	100.0	.0	.0
Secondary Contact Recreation	23,446.1	86.5	.0	13.5
Undesignated Surface Waters	19.8	.0	.0	100.0
Warm Water Aquatic Life	184.4	45.3	.0	54.7
Wildlife Habitat	6,910.5	100.0	.0	.0

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Idaho Causes of Impairment
for Threatened and Impaired Rivers and Streams
Reporting Year 2008

Cause of Impairment	Cause of Impairment Group	Miles Threatened or Impaired
Sedimentation/Siltation	Sediment	17,060.4
Temperature, Water	Temperature	15,292.7
Phosphorus, Total	Nutrients	5,338.2
Combined Biota/Habitat Bioassessments (Streams)	Cause Unknown - Impaired Biota	4,913.1
Other Flow Regime Alterations	Flow Alteration(s)	3,795.2
Fecal Coliform	Pathogens	3,645.0
Physical Substrate Habitat Alterations	Habitat Alterations	3,629.9
Cause Unknown	Cause Unknown	2,477.5
Escherichia Coli (E. Coli)	Pathogens	2,359.7
Total Suspended Solids (TSS)	Turbidity	1,877.0
Nutrient/Eutrophication Biological Indicators	Nutrients	1,643.9
Low Flow Alterations	Flow Alteration(s)	1,364.3
Dissolved Oxygen	Organic Enrichment/Oxygen Depletion	950.2
Oil and Grease	Oil and Grease	665.3
Habitat Assessment (Streams)	Cause Unknown - Impaired Biota	575.8
Nitrogen, Total	Nutrients	521.3
Ammonia, Un-ionized	Ammonia	465.0
Fish Bioassessments	Cause Unknown - Impaired Biota	459.4
Zinc	Metals (other than Mercury)	342.1
Cadmium	Metals (other than Mercury)	337.9
Mercury	Mercury	306.9
Lead	Metals (other than Mercury)	271.8
Benthic Macroinvertebrates Bioassessments	Cause Unknown - Impaired Biota	229.5
Arsenic	Metals (other than Mercury)	210.2
Dissolved Gas Supersaturation	Other Cause	200.1
Selenium	Metals (other than Mercury)	151.9
pH	pH/Acidity/Caustic Conditions	82.7
Copper	Metals (other than Mercury)	49.1
Total Coliform	Pathogens	24.6
Fish Kill(s)	Cause Unknown - Fish Kills	10.0
Aquatic Plant Bioassessments	Cause Unknown - Impaired Biota	9.7
High Flow Regime	Flow Alteration(s)	4.9
Aquatic Plants (Macrophytes)	Noxious Aquatic Plants	4.7
Particle Distribution (Embeddedness)	Sediment	3.0

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Idaho Probable Sources of Impairments
for Threatened and Impaired Rivers and Streams
Reporting Year 2008

Probable Source	Probable Source Group	Miles Threatened or Impaired
Rangeland Grazing	Agriculture	1,975.4
Livestock (Grazing Or Feeding Operations)	Agriculture	1,364.8
Grazing In Riparian Or Shoreline Zones	Agriculture	1,234.7
Loss Of Riparian Habitat	Habitat Alterations (Not Directly Related To Hydromodification)	597.7
Managed Pasture Grazing	Agriculture	592.5
Source Unknown	Unknown	590.0
Flow Alterations From Water Diversions	Hydromodification	548.1
Channelization	Hydromodification	533.1
Impacts From Hydrostructure Flow Regulation/Modification	Hydromodification	519.0
Irrigated Crop Production	Agriculture	413.6
Streambank Modifications/Destabilization	Hydromodification	394.3
Natural Sources	Natural/Wildlife	333.6
Silviculture Activities	Silviculture (Forestry)	308.1
Agriculture	Agriculture	298.4
Highway/Road/Bridge Runoff (Non-Construction Related)	Urban-Related Runoff/Stormwater	281.1
Impacts From Abandoned Mine Lands (Inactive)	Resource Extraction	264.2
Upstream Impoundments (E.G., Pl-566 Nrcs Structures)	Hydromodification	260.9
Placer Mining	Resource Extraction	221.6
Forest Roads (Road Construction And Use)	Silviculture (Forestry)	210.9
Habitat Modification - Other Than Hydromodification	Habitat Alterations (Not Directly Related To Hydromodification)	133.9
Crop Production (Crop Land Or Dry Land)	Agriculture	114.4
Non-Irrigated Crop Production	Agriculture	92.4
Highways, Roads, Bridges, Infrastructure (New Construction)	Construction	68.8
Construction Stormwater Discharge (Permitted)	Construction	64.2
Dam Construction (Other Than Upstream Flood Control Projects)	Hydromodification	62.0
Municipal Point Source Discharges	Municipal Dishcarges/Sewage	58.5
Surface Mining	Resource Extraction	55.0
Animal Feeding Operations (Nps)	Agriculture	53.1
Site Clearance (Land Development Or Redevelopment)	Construction	39.7
Mill Tailings	Industrial	39.3
Sources Outside State Jurisdiction Or Borders	Other	37.9
Acid Mine Drainage	Resource Extraction	31.2
Dredging (E.G., For Navigation Channels)	Hydromodification	30.9
Mine Tailings	Resource Extraction	28.2
Wet Weather Discharges (Point Source And Combination Of Stormwater, Sso Or Cso)	Municipal Dishcarges/Sewage	25.8
Other Recreational Pollution Sources	Recreation And Tourism (Non-Boating)	18.5
Post-Development Erosion And Sedimentation	Hydromodification	10.4
Dam Or Impoundment	Hydromodification	10.1
Aquaculture (Permitted)	Aquaculture	8.8
Subsurface (Hardrock) Mining	Resource Extraction	7.5
Dredge Mining	Resource Extraction	2.0

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Idaho Assessed Waters
Summary of Water Quality Attainment for Lakes, Reservoirs, and Ponds
Reporting Year 2008

Description of this table Assessed Status Acres Assessed 223,244.3 Unassessed 245,955.7 Total Acres 469,200.0

Description of this table Attainment Status Acres Good 2,781.0 Threatened .0 Impaired 220,463.3 Total Acres Assessed 223,244.3

Description of this table TMDL Development Status Acres All TMDLs completed 17,135.9 TMDL alternative .0 Non-pollutant impairment 950.1 TMDL needed 202,377.3 Total Threatened and Impaired 220,463.3

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Idaho Assessed Waters
Designated Use Support for Lakes, Reservoirs, and Ponds
Reporting Year 2008*

* Waters assessed for more than one designated use are included in multiple designated use groups below.

Designated Use	Acres Assessed	Percent Good	Percent Threatened	Percent Impaired	% Good
					% Threatened
					% Impaired
Agricultural Water Supply	68.8	100.0	.0	.0
Cold Water Aquatic Life	223,041.7	1.4	.0	98.6
Domestic Water Supply	3.4	100.0	.0	.0
Industrial Water Supply	68.8	100.0	.0	.0
Primary Contact Recreation	23,488.7	36.1	.0	63.9
Salmonid Spawning	81,101.4	.1	.0	99.9
Secondary Contact Recreation	11,043.4	.3	.0	99.7
Undesignated Surface Waters	202.6	.0	.0	100.0
Warm Water Aquatic Life	6,056.5	.0	.0	100.0
Wildlife Habitat	68.8	100.0	.0	.0

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Idaho Causes of Impairment
for Threatened and Impaired Lakes, Reservoirs, and Ponds
Reporting Year 2008

Cause of Impairment	Cause of Impairment Group	Acres Threatened or Impaired
Mercury	Mercury	110,147.8
Phosphorus, Total	Nutrients	94,172.3
Other Flow Regime Alterations	Flow Alteration(s)	84,707.2
Sedimentation/Siltation	Sediment	68,459.9
Dissolved Oxygen	Organic Enrichment/Oxygen Depletion	56,389.0
Nutrient/Eutrophication Biological Indicators	Nutrients	55,946.7
Chlorophyll-A	Algal Growth	55,519.2
Zinc	Metals (other than Mercury)	27,968.3
Lead	Metals (other than Mercury)	27,968.3
Cadmium	Metals (other than Mercury)	27,968.3
Cause Unknown	Cause Unknown	6,436.5
Temperature, Water	Temperature	3,951.5
Total Suspended Solids (TSS)	Turbidity	1,927.4
pH	pH/Acidity/Caustic Conditions	604.1
Escherichia Coli (E. Coli)	Pathogens	262.2
Combined Biota/Habitat Bioassessments (Streams)	Cause Unknown - Impaired Biota	141.6
Physical Substrate Habitat Alterations	Habitat Alterations	131.6
Low Flow Alterations	Flow Alteration(s)	86.7
Nitrogen, Total	Nutrients	5.9

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Idaho Probable Sources of Impairments
for Threatened and Impaired Lakes, Reservoirs, and Ponds
Reporting Year 2008

Probable Source	Probable Source Group	Acres Threatened or Impaired
Livestock (Grazing Or Feeding Operations)	Agriculture	15.7
Forest Roads (Road Construction And Use)	Silviculture (Forestry)	12.7
Flow Alterations From Water Diversions	Hydromodification	12.6
Managed Pasture Grazing	Agriculture	8.6
Rangeland Grazing	Agriculture	8.0
Impacts From Hydrostructure Flow Regulation/Modification	Hydromodification	7.7
Loss Of Riparian Habitat	Habitat Alterations (Not Directly Related To Hydromodification)	5.0
Grazing In Riparian Or Shoreline Zones	Agriculture	5.0
Streambank Modifications/Destabilization	Hydromodification	5.0
Agriculture	Agriculture	5.0
Channelization	Hydromodification	5.0
Non-Irrigated Crop Production	Agriculture	.9
Silviculture Activities	Silviculture (Forestry)	.7

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Idaho Causes of Impairment for Reporting Year 2008

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Idaho Probable Sources Contributing to Impairments
for Reporting Year 2008

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Idaho TMDL Alternatives by Cause of Impairment 2008

No TMDL Alternatives reported.

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Idaho Previously Impaired Waters Now Attaining All Uses

No previously impaired waters reported as attaining all uses.

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Idaho Causes of Impairment for 303(d) Listed Waters

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
Temperature	376
Sediment	258
Cause Unknown - Impaired Biota	225
Pathogens	157
Metals (other than Mercury)	109
Cause Unknown	94
Nutrients	40
Mercury	22
Oil and Grease	12
Organic Enrichment/Oxygen Depletion	11
Ammonia	9
Other Cause	7
Turbidity	3
Flow Alteration(s)	3
pH/Acidity/Caustic Conditions	2
Algal Growth	1
Cause Unknown - Fish Kills	1

Total: 1,330 Causes of Impairment

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Idaho Cumulative TMDLs by Pollutant

This chart includes TMDLs since October 1, 1995.

NOTE: Click on the underlined "Pollutant" value to see associated listed waters for which a TMDL was developed. Click on the underlined "Number of TMDLs" value to see a listing of those TMDLs for the pollutant.
Pollutant	Number of TMDLs	Number of Causes of Impairment Addressed
Temperature	439	439
Sediment	371	371
Total Suspended Solids (TSS)	139	139
Nutrients	111	111
Phosphorus, Total	97	104
Phosphorus	92	96
Cadmium	60	60
Zinc	60	60
Lead	57	57
Bacteria	49	49
Escherichia Coli (E. Coli)	30	30
Dissolved Oxygen	26	26
Pathogens	18	18
Enterococcus Bacteria	10	10
Total Dissolved Gas	6	6
DDD	5	5
DDE	5	5
DDT	5	5
Dieldrin	5	5
Suspended Sediment	5	5
Erosion	4	4
Ammonia	3	3
Copper	3	3
Nitrogen	3	3
Nitrogen, Total	2	2
Total Inorganic Nitrogen	2	2
Turbidity	2	2
Mercury	1	1
Oil and Grease	1	1

Total: 1,611 TMDLs; 1,622 Causes of Impairment Addressed

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Idaho Cumulative Number of TMDLs

EPA Fiscal Year starts October 1 and ends September 30.

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	4	4
1997	14	14
1998	5	5
1999	19	21
2000	375	375
2001	72	75
2002	81	81
2003	120	120
2004	240	242
2005	160	160
2006	146	150
2007	50	50
2008	232	232
2009	93	93

Total: 1,611 TMDLs; 1,622 Causes of Impairment Addressed

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Idaho Cumulative Number of TMDLs for Indian Country Waters

EPA Fiscal Year starts October 1 and ends September 30.

NOTE:Click on the underlined "Number of TMDLs" value for a detailed list of the TMDLs for the fiscal year.
Fiscal Year	Number of TMDLs	Number of Causes of Impairment Addressed
1999	9	9
2000	124	124
2004	11	17
2005	1	10

Total: 145 TMDLs; 145 Causes of Impairment

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TMDL Document Search

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