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Montana Assessment Summary for Reporting Year 2006

	Size of Water
	Rivers and Streams (Miles)	Lakes, Reservoirs, and Ponds (Acres)
Good Waters	2,784.9	74,482.2
Previously impaired waters       now attaining all uses
Threatened Waters		6,029.9
TMDL completed		2,680.0
TMDL alternative
Non-pollutant impairment
TMDL needed		3,349.9
Impaired Waters	15,221.0	499,020.1
TMDL completed	690.4	300.0
TMDL alternative
Non-pollutant impairment	1,731.3	37,738.0
TMDL needed	12,799.2	460,982.1
New TMDLs completed	739.1	1,600.0
Remaining TMDLs needed	12,060.1	459,382.1
Total Assessed Waters	18,005.9	579,532.2
Total Waters	176,750.0	844,802.0
Percent of Waters Assessed	10.2	68.6

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Summary of Water Quality Assessments for Each Waterbody Type
for Reporting Year 2006

Montana Assessed Waters
Summary of Water Quality Attainment for Rivers and Streams
Reporting Year 2006

Description of this table Assessed Status Miles Assessed 18,005.9 Unassessed 158,744.2 Total Miles 176,750.0

Description of this table Attainment Status Miles Good 2,784.9 Threatened .0 Impaired 15,221.0 Total Miles Assessed 18,005.9

Description of this table TMDL Development Status Miles All TMDLs completed 1,429.5 TMDL alternative .0 Non-pollutant impairment 1,731.3 TMDL needed 12,060.1 Total Threatened and Impaired 15,221.0

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Montana Assessed Waters
Designated Use Support for Rivers and Streams
Reporting Year 2006*

* 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
Agricultural	12,452.9	89.3	.0	10.7
Aquatic Life	16,924.8	18.6	.0	81.4
Cold Water Fishery	10,249.1	16.1	.0	83.9
Drinking Water	11,196.6	69.3	.1	30.6
Industrial	12,601.5	89.1	.0	10.9
Primary Contact Recreation	14,806.0	60.9	1.0	38.1
Warm Water Fishery	6,485.9	17.7	.0	82.3

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Montana Causes of Impairment
for Threatened and Impaired Rivers and Streams
Reporting Year 2006

Cause of Impairment	Cause of Impairment Group	Miles Threatened or Impaired
Alteration in Stream-Side or Littoral Vegetative Covers	Habitat Alterations	7,683.9
Sedimentation/Siltation	Sediment	6,368.4
Phosphorus, Total	Nutrients	4,590.1
Low Flow Alterations	Flow Alteration(s)	4,251.4
Physical Substrate Habitat Alterations	Habitat Alterations	3,271.3
Lead	Metals (other than Mercury)	3,027.1
Copper	Metals (other than Mercury)	2,809.8
Total Kjehldahl Nitrogen (TKN)	Nutrients	2,729.2
Temperature, Water	Temperature	2,393.1
Nitrate/Nitrite (Nitrite + Nitrate as N)	Nutrients	2,065.4
Mercury	Mercury	1,761.4
Iron	Metals (other than Mercury)	1,713.9
Nitrogen, Total	Nutrients	1,713.6
Zinc	Metals (other than Mercury)	1,582.6
Cadmium	Metals (other than Mercury)	1,517.7
Chlorophyll-A	Algal Growth	1,475.0
Arsenic	Metals (other than Mercury)	1,391.2
Other Flow Regime Alterations	Flow Alteration(s)	1,272.4
Total Dissolved Solids (TDS)	Salinity/Total Dissolved Solids/Chlorides/Sulfates	1,177.0
Solids (Suspended/Bedload)	Sediment	983.2
Salinity	Salinity/Total Dissolved Solids/Chlorides/Sulfates	766.1
Sulfates	Salinity/Total Dissolved Solids/Chlorides/Sulfates	595.1
Fish Passage Barrier	Habitat Alterations	542.0
Dissolved Oxygen	Organic Enrichment/Oxygen Depletion	447.8
Fecal Coliform	Pathogens	433.6
Specific Conductivity	Salinity/Total Dissolved Solids/Chlorides/Sulfates	391.7
Other Anthropogenic Substrate Alterations	Habitat Alterations	373.2
pH	pH/Acidity/Caustic Conditions	343.9
Selenium	Metals (other than Mercury)	321.4
Excess Algal Growth	Algal Growth	307.8
Nitrates	Nutrients	306.5
Chromium, Total	Metals (other than Mercury)	300.7
Aluminum	Metals (other than Mercury)	289.7
Cause Unknown	Cause Unknown	249.0
Ammonia, Un-ionized	Ammonia	227.9
Nitrogen, Nitrate	Nutrients	222.8
Organic Enrichment (Sewage) Biological Indicators	Organic Enrichment/Oxygen Depletion	181.5
Nickel	Metals (other than Mercury)	167.2
Turbidity	Turbidity	166.8
Manganese	Metals (other than Mercury)	142.5
High Flow Regime	Flow Alteration(s)	141.7
Silver	Metals (other than Mercury)	140.6
Total Suspended Solids (TSS)	Turbidity	124.0
Alterations in Wetland Habitats	Habitat Alterations	108.0
Other Cause	Other Cause	105.8
Habitat Assessment (Streams)	Cause Unknown - Impaired Biota	86.7
Uranium	Radiation	81.3
Escherichia Coli (E. Coli)	Pathogens	75.1
Antimony	Toxic Inorganics	72.5
Cyanide	Toxic Inorganics	72.1
Benthic Macroinvertebrates Bioassessments	Cause Unknown - Impaired Biota	64.5
Ammonia, Total	Ammonia	62.5
Polychlorinated Biphenyls (PCBs)	Polychlorinated Biphenyls (PCBs)	54.3
Biochemical Oxygen Demand (BOD)	Organic Enrichment/Oxygen Depletion	51.3
Sodium	Salinity/Total Dissolved Solids/Chlorides/Sulfates	36.6
Bottom Deposits	Sediment	28.8
Nutrient/Eutrophication Biological Indicators	Nutrients	25.7
Oil and Grease	Oil and Grease	23.7
DDE	Pesticides	21.6
Polycyclic Aromatic Hydrocarbons (PAHs) (Aquatic Ecosystems)	Toxic Organics	18.4
Mercury in Water Column	Mercury	18.2
Pentachlorobenzene	Toxic Organics	17.8
Chloride	Salinity/Total Dissolved Solids/Chlorides/Sulfates	16.4
Combined Biota/Habitat Bioassessments (Streams)	Cause Unknown - Impaired Biota	12.1
Aquatic Plants - Native	Nuisance Native Species	11.1
Cobalt	Metals (other than Mercury)	11.0
Barium	Radiation	11.0
Phosphate	Nutrients	10.4
Non-Native Fish/Shellfish/Zooplankton	Nuisance Exotic Species	9.8
Thallium	Metals (other than Mercury)	5.4
Beryllium	Metals (other than Mercury)	4.9
Dissolved Gas Supersaturation	Other Cause	2.8

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Montana Probable Sources of Impairments
for Threatened and Impaired Rivers and Streams
Reporting Year 2006

Probable Source	Probable Source Group	Miles Threatened or Impaired
Agriculture	Agriculture	5,203.6
Grazing In Riparian Or Shoreline Zones	Agriculture	5,125.0
Source Unknown	Unknown	4,017.1
Irrigated Crop Production	Agriculture	3,831.8
Natural Sources	Natural/Wildlife	3,278.5
Streambank Modifications/Destablization	Hydromodification	2,307.8
Rangeland Grazing	Agriculture	2,085.8
Impacts From Hydrostructure Flow Regulation/Modification	Hydromodification	2,058.0
Impacts From Abandoned Mine Lands (Inactive)	Resource Extraction	1,867.2
Channelization	Hydromodification	1,798.8
Loss Of Riparian Habitat	Habitat Alterations (Not Directly Related To Hydromodification)	1,713.2
Flow Alterations From Water Diversions	Hydromodification	1,374.1
Dam Or Impoundment	Hydromodification	1,282.5
Highways, Roads, Bridges, Infrasturcture (New Construction)	Construction	1,049.8
Forest Roads (Road Construction And Use)	Silviculture (Forestry)	958.6
Silviculture Activities	Silviculture (Forestry)	877.8
Municipal Point Source Discharges	Municipal Dishcarges/Sewage	735.3
Highway/Road/Bridge Runoff (Non-Construction Related)	Urban-Related Runoff/Stormwater	663.4
Acid Mine Drainage	Resource Extraction	648.6
Non-Irrigated Crop Production	Agriculture	642.2
Crop Production (Crop Land Or Dry Land)	Agriculture	579.1
Dam Construction (Other Than Upstream Flood Control Projects)	Hydromodification	556.8
Unspecified Unpaved Road Or Trail	Urban-Related Runoff/Stormwater	541.9
Mine Tailings	Resource Extraction	493.4
Silviculture Harvesting	Silviculture (Forestry)	473.4
Habitat Modification - Other Than Hydromodification	Habitat Alterations (Not Directly Related To Hydromodification)	467.7
Site Clearance (Land Development Or Redevelopment)	Construction	464.9
Animal Feeding Operations (Nps)	Agriculture	404.9
Mill Tailings	Industrial	391.1
Contaminated Sediments	Legacy/Historical Pollutants	289.2
Placer Mining	Resource Extraction	263.7
Subsurface (Hardrock) Minining	Resource Extraction	263.3
Industrial Point Source Discharge	Industrial	248.8
Transfer Of Water From An Outside Watershed	Hydromodification	179.7
Dredge Mining	Resource Extraction	138.5
Upstream Impoundments (E.G., Pl-566 Nrcs Structures)	Hydromodification	128.6
Surface Mining	Resource Extraction	127.8
Livestock (Grazing Or Feeding Operations)	Agriculture	125.3
Hydrostructure Impacts On Fish Passage	Hydromodification	124.8
Post-Development Erosion And Sedimentation	Hydromodification	116.2
Residential Districts	Urban-Related Runoff/Stormwater	111.5
Drought-Related Impacts	Natural/Wildlife	108.6
Above Ground Storage Tank Leaks (Tank Farms)	Spills/Dumping	105.0
On-Site Treatment Systems (Septic Systems And Similar Decencentralized Systems)	Municipal Dishcarges/Sewage	96.6
Golf Courses	Recreation And Tourism (Non-Boating)	94.7
Impacts From Resort Areas (Winter And Non-Winter Resorts)	Recreation And Tourism (Non-Boating)	92.6
Watershed Runoff Following Forest Fire	Silviculture (Forestry)	90.0
Managed Pasture Grazing	Agriculture	89.8
Wet Weather Discharges (Point Source And Combination Of Stormwater, Sso Or Cso)	Municipal Dishcarges/Sewage	83.6
Upstream Source	Other	73.4
Coal Mining	Resource Extraction	62.3
Permitted Runoff From Confined Animal Feeding Operations (Cafos)	Agriculture	51.3
Aquaculture (Permitted)	Aquaculture	50.1
Channel Erosion/Incision From Upstream Hydromodifications	Hydromodification	49.3
Low Water Crossing	Other	47.2
Crop Production With Subsurface Drainage	Agriculture	44.5
Atmospheric Deposition - Nitrogen	Atmospheric Deposition	37.1
Hardrock Mining Discharges (Permitted)	Resource Extraction	35.9
Atmospheric Deposition - Toxics	Atmospheric Deposition	33.6
Sediment Resuspension (Clean Sediment)	Hydromodification	31.1
Unspecified Urban Stormwater	Urban-Related Runoff/Stormwater	28.7
Yard Maintenance	Urban-Related Runoff/Stormwater	26.3
Spills From Trucks Or Trains	Spills/Dumping	26.0
Sediment Resuspension (Contaminated Sediment)	Hydromodification	23.4
Other Recreational Pollution Sources	Recreation And Tourism (Non-Boating)	21.3
Petroleum/Natural Gas Production Activities (Permitted)	Industrial	18.4
Pipeline Breaks	Spills/Dumping	18.4
Wet Weather Discharges (Non-Point Source)	Urban-Related Runoff/Stormwater	14.7
Construction Stormwater Discharge (Permitted)	Construction	14.0
Discharges From Municipal Separate Storm Sewer Systems (Ms4)	Urban-Related Runoff/Stormwater	11.8
Freshettes Or Major Flooding	Natural/Wildlife	11.2
Septage Disposal	Municipal Dishcarges/Sewage	9.2
Industrial/Commercial Site Stormwater Discharge (Permittted)	Urban-Related Runoff/Stormwater	7.6
Open Pit Mining	Resource Extraction	7.4
Municipal (Urbanized High Density Area)	Urban-Related Runoff/Stormwater	7.0
Baseflow Depletion From Groundwater Withdrawals	Hydromodification	4.5
Heap-Leach Extraction Mining	Resource Extraction	4.1
Sources Outside State Juristiction Or Borders	Other	2.8
Erosion From Derelict Land (Barren Land)	Hydromodification	1.8

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Montana Assessed Waters
Summary of Water Quality Attainment for Lakes, Reservoirs, and Ponds
Reporting Year 2006

Description of this table Assessed Status Acres Assessed 579,532.2 Unassessed 265,269.8 Total Acres 844,802.0

Description of this table Attainment Status Acres Good 74,482.2 Threatened 6,029.9 Impaired 499,020.1 Total Acres Assessed 579,532.2

Description of this table TMDL Development Status Acres All TMDLs completed 4,580.0 TMDL alternative .0 Non-pollutant impairment 37,738.0 TMDL needed 462,732.0 Total Threatened and Impaired 505,050.0

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Montana Assessed Waters
Designated Use Support for Lakes, Reservoirs, and Ponds
Reporting Year 2006*

* 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	308,533.3	82.4	.0	17.6
Aquatic Life	334,229.2	34.4	1.8	63.8
Cold Water Fishery	274,624.4	80.0	2.2	17.8
Drinking Water	531,928.6	42.7	.0	57.3
Industrial	312,638.0	97.6	.0	2.4
Primary Contact Recreation	567,343.2	44.2	.0	55.8
Warm Water Fishery	51,920.8	50.0	.0	50.0

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Montana Causes of Impairment
for Threatened and Impaired Lakes, Reservoirs, and Ponds
Reporting Year 2006

Cause of Impairment	Cause of Impairment Group	Acres Threatened or Impaired
Mercury	Mercury	392,275.8
Lead	Metals (other than Mercury)	257,122.0
Aquatic Plants - Native	Nuisance Native Species	248,500.0
Sedimentation/Siltation	Sediment	135,721.5
Phosphorus, Total	Nutrients	135,361.2
Nitrogen, Total	Nutrients	133,206.9
Polychlorinated Biphenyls (PCBs)	Polychlorinated Biphenyls (PCBs)	129,356.8
Other Flow Regime Alterations	Flow Alteration(s)	44,980.8
Excess Algal Growth	Algal Growth	40,780.0
Arsenic	Metals (other than Mercury)	36,809.0
Ammonia, Un-ionized	Ammonia	35,180.0
Thallium	Metals (other than Mercury)	35,180.0
Salinity	Salinity/Total Dissolved Solids/Chlorides/Sulfates	13,697.0
Selenium	Metals (other than Mercury)	13,575.0
Sulfates	Salinity/Total Dissolved Solids/Chlorides/Sulfates	9,400.0
Cadmium	Metals (other than Mercury)	8,619.0
Physical Substrate Habitat Alterations	Habitat Alterations	7,780.8
Chlorophyll-A	Algal Growth	6,620.0
Other Anthropogenic Substrate Alterations	Habitat Alterations	4,455.8
Dissolved Oxygen	Organic Enrichment/Oxygen Depletion	4,152.6
Endrin Aldehyde	Pesticides	3,800.0
DDT	Pesticides	3,800.0
Endosulfan	Pesticides	3,800.0
Total Dissolved Solids (TDS)	Salinity/Total Dissolved Solids/Chlorides/Sulfates	3,800.0
Low Flow Alterations	Flow Alteration(s)	3,780.8
Cause Unknown	Cause Unknown	3,780.8
Chromium, Total	Metals (other than Mercury)	3,780.8
BOD, Sediment Load (Sediment Oxygen Demand)	Organic Enrichment/Oxygen Depletion	2,680.0
Copper	Metals (other than Mercury)	1,923.0
Iron	Metals (other than Mercury)	1,903.0
Temperature, Water	Temperature	1,600.0
Total Suspended Solids (TSS)	Turbidity	1,600.0
Total Kjehldahl Nitrogen (TKN)	Nutrients	352.6
Other Cause	Other Cause	80.0
Zinc	Metals (other than Mercury)	20.0
pH	pH/Acidity/Caustic Conditions	20.0
Alteration in Stream-Side or Littoral Vegetative Covers	Habitat Alterations	9.0

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Montana Probable Sources of Impairments
for Threatened and Impaired Lakes, Reservoirs, and Ponds
Reporting Year 2006

Probable Source	Probable Source Group	Acres Threatened or Impaired
Agriculture	Agriculture	308,934.1
Impacts From Abandoned Mine Lands (Inactive)	Resource Extraction	291,080.8
Atmospheric Deposition - Toxics	Atmospheric Deposition	259,099.0
Historic Bottom Deposits (Not Sediment)	Legacy/Historical Pollutants	250,500.0
Municipal Point Source Discharges	Municipal Dishcarges/Sewage	164,686.9
Source Unknown	Unknown	156,792.2
Impacts From Hydrostructure Flow Regulation/Modification	Hydromodification	143,389.4
Unspecified Urban Stormwater	Urban-Related Runoff/Stormwater	126,006.9
Upstream Impoundments (E.G., Pl-566 Nrcs Structures)	Hydromodification	126,006.9
Silviculture Harvesting	Silviculture (Forestry)	126,006.9
Atmospheric Deposition - Nitrogen	Atmospheric Deposition	126,006.9
Natural Sources	Natural/Wildlife	46,263.8
Acid Mine Drainage	Resource Extraction	40,560.8
Internal Nutrient Recycling	Natural/Wildlife	35,180.0
On-Site Treatment Systems (Septic Systems And Similar Decencentralized Systems)	Municipal Dishcarges/Sewage	35,180.0
Site Clearance (Land Development Or Redevelopment)	Construction	35,180.0
Dam Or Impoundment	Hydromodification	32,350.0
Irrigated Crop Production	Agriculture	23,289.7
Silviculture Activities	Silviculture (Forestry)	8,669.9
Forest Roads (Road Construction And Use)	Silviculture (Forestry)	6,029.9
Inappropriate Waste Disposal	Spills/Dumping	5,500.0
Placer Mining	Resource Extraction	5,500.0
Drought-Related Impacts	Natural/Wildlife	4,888.0
Grazing In Riparian Or Shoreline Zones	Agriculture	4,852.1
Highway/Road/Bridge Runoff (Non-Construction Related)	Urban-Related Runoff/Stormwater	3,800.0
Habitat Modification - Other Than Hydromodification	Habitat Alterations (Not Directly Related To Hydromodification)	3,780.8
Highways, Roads, Bridges, Infrasturcture (New Construction)	Construction	3,364.0
Upstream Source	Other	3,332.1
Rangeland Grazing	Agriculture	3,332.1
Low Water Crossing	Other	1,126.0
Non-Irrigated Crop Production	Agriculture	675.0
Upstream/Dowstream Source	Other	352.6
Petroleum/Natural Gas Activities	Resource Extraction	9.0

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Montana Causes of Impairment for Reporting Year 2006

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Montana Probable Sources Contributing to Impairments
for Reporting Year 2006

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Montana TMDL Alternatives by Cause of Impairment 2006

No TMDL Alternatives reported.

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Montana Previously Impaired Waters Now Attaining All Uses

No previously impaired waters reported as attaining all uses.

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Montana 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
Metals (other than Mercury)	691
Nutrients	513
Sediment	379
Algal Growth	100
Temperature	89
Mercury	72
Salinity/Total Dissolved Solids/Chlorides/Sulfates	60
Turbidity	57
Organic Enrichment/Oxygen Depletion	21
Pathogens	17
pH/Acidity/Caustic Conditions	16
Toxic Inorganics	13
Cause Unknown	11
Ammonia	11
Cause Unknown - Impaired Biota	5
Pesticides	4
Polychlorinated Biphenyls (PCBs)	3
Habitat Alterations	3
Other Cause	3
Toxic Organics	3
Radiation	2
Nuisance Native Species	2
Oil and Grease	1
Nuisance Exotic Species	1

Total: 2,077 Causes of Impairment

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Montana 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
Sediment	129	171
Lead	48	49
Copper	43	43
Sedimentation/Siltation	39	41
Cadmium	32	33
Nitrogen	32	44
Phosphorus	30	43
Zinc	30	30
Arsenic	26	26
Iron	22	22
Siltation	19	19
Temperature	17	23
Phosphorus, Total	14	15
Manganese	12	12
Nitrogen, Total	12	12
Suspended Solids	10	10
Thermal Modifications	10	10
Aluminum	9	9
Fecal Coliform	8	8
Fecal	7	9
Total Residual Chlorine	6	6
Ammonia	5	5
Mercury	5	5
Selenium	4	4
Total Dissolved Solids (TDS)	4	4
Antimony	3	3
Salinity	3	4
Tin	3	3
pH	3	3
Chromium	2	2
Polychlorinated Biphenyls (PCBs)	2	2
Silver	2	2
Cyanide	1	1
Escherichia Coli (E. Coli)	1	1
Fluoride	1	1
Nickel	1	1
Nitrate	1	1
Noxious Aquatic Plants	1	1
Nutrients	1	3
Organic Enrichment/Low Dissolved Oxygen	1	1
Salinity/Total Dissolved Solids/Chlorides	1	1
Salinity/Total Dissolved Solids/Sulfates	1	1
Sulfate	1	1
Sulfates	1	1
Total Kjehldahl Nitrogen (TKN)	1	1
Total Suspended Solids (TSS)	1	1
Total Toxics	1	1
Turbidity	1	1

Total: 607 TMDLs; 690 Causes of Impairment Addressed

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Montana 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
1997	10	10
1998	32	37
1999	18	33
2001	1	1
2002	16	18
2003	46	49
2004	52	69
2005	67	71
2006	123	126
2007	34	36
2008	89	119
2009	119	121

Total: 607 TMDLs; 690 Causes of Impairment Addressed

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TMDL Document Search

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