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Total Maximum Daily Loads

Section 303(d) of the Clean Water Act requires states and tribes to identify and prioritize water bodies that do not meet water quality standards through Idaho’s Integrated Report. Idaho must develop a water quality improvement plan, called a total maximum daily load (TMDL), for those water bodies not meeting water quality standards. A subbasin assessment is the first step toward developing a TMDL.

Subbasin Assessments and TMDLs

In Idaho, TMDLs are developed on a subbasin level, which means water bodies and pollutants within a hydrologic subbasin are generally addressed in a single document. A subbasin is based on a cataloging unit of the US Geological Survey (USGS) (i.e., a subbasin is the same as a USGS 4th-field hydrologic unit code or HUC). Idaho has 86 subbasins (HUCs) entirely or partially within its borders.

Five-Year Reviews

Five-year reviews address the water bodies in a subbasin that are in Category 4a of Idaho’s most recent Integrated Report. Five-year reviews outline the appropriateness of beneficial uses, water quality criteria, TMDL targets, pollutant allocations, and other assumptions of the TMDL. The review describes current water quality status, pollutant sources, and recent pollution control efforts in the subbasin. The 5-year review process may also recommend delistings or TMDL revisions to incorporate updated information.

TMDL Implementation Plans

TMDL implementation plans are written following EPA approval of a TMDL, typically, within 18 months. An implementation plan details the actions needed to achieve load reductions, outlines a schedule of those actions, and specifies monitoring needed to document action and progress toward meeting water quality standards. Implementation plans provide a framework for local stakeholders to use to reach the goals established in the TMDL.

Subbasin Assessments, Five-Year Reviews, and Implementation

Subbasin NameHydrologic Unit Code (HUC)TMDL StatusImplementation Plan StatusFive-Year Review Status
American Falls Subbasin17040206

Approved by EPA August 2012

Agriculture completed May 2014 
Bear River Basin/Malad River Subbasin16010201 16010102 16010204 16010202

Approved by EPA June 2006

Bear River Basin Addendum approved by EPA September 2013

Lower Bear/Malad Subbasin Agriculture completed May 2010

Central Bear (Bear River Main Stem) Agriculture completed October 2008

Northern Middle Bear Agriculture completed September 2008

Southern Middle Bear Agriculture completed September
2008

Bear Lake Subbasin Agriculture completed July 2008

Bear River/Malad River Forest Svc. completed April 2008

Daniels Watershed completed 2007

Cub River Watershed Agriculture completed September 2006

Submitted to EPA January 2017
Beaver-Camas Subbasin17040214Approved by EPA August 2005Under development 
Big Lost River Subbasin17040218

Approved by EPA August 2004

Addendum approved by EPA December 2011

2019 Addendum and Five-Year Review approved by EPA June 2019

Agriculture completed May 2011

See TMDL Addendum
Big Wood River Subbasin17040219

Approved by EPA May 2002

Errata approved by EPA February 2012

Temperature Addendum approved by EPA December 2013

Agriculture completed October 2006, revised February 2014Completed December 2017
Birch Creek Subbasin17040216Assessment completed March 2005  
Blackfoot River Subbasin17040207

Approved by EPA April 2002

Brush Creek Temperature TMDL approved by EPA November 2007

Blackfoot River TMDL Addendum approved by EPA October 2013

Completed February 2006

Completed August 2015
Boise – Mores Creek Subbasin17050112Approved by EPA February 2010 Sediment and E. coli completed May 2019
Boise River (Lower) Subbasin17050114

Approved by EPA January 2000

Assessments completed December 2001

Addendum approved by EPA June 2008

Lake Lowell TMDL approved by EPA December 2010

Sediment and Bacteria Addendum approved by EPA September 2015

Total Phosphorus Addendum approved by EPA December 2015

Completed December 2003

Phosphorus completed December 2008

Lake Lowell completed June 2012

Completed February 2009
Boise River (North/Middle Fork) Subbasin17050111Assessment completed November 2002NA 
Boise River (South Fork) Subbasin17050113

Assessment completed 2002

TMDL approved by EPA March 2009

See TMDL Appendix J
See TMDL
Brownlee Reservoir Subbasin includes Wildhorse River watershed17050201

Approved by EPA November 2003

Wildhorse River TMDL approved by EPA October 2007

Agriculture completed September 2004, revised 2014

Wildhorse River Agriculture completed March 2010

Wildhorse River Forestry completed February 2010

Weiser Flat completed August 2015

Wildhorse River completed August 2015

Bruneau River Subbasin17050102

Approved by EPA March 2001

Jacks Creek Aquaculture Addendum TMDL approved by EPA November 2007

Bruneau River Agriculture completed June 2002, revised March 2013

Jacks Creek Agriculture completed June 2002, revised March 2013

 
C.J. Strike Reservoir Subbasin17050101

Approved by EPA June 2006

Agriculture completed November 2007

Dissolved Oxygen completed November 2007, revised December 2008

 
Camas Creek Subbasin17040220

Approved by EPA September 2005

2016 Temperature Addendum approved by EPA December 2016

Agriculture completed August 2007, revised March 2013Completed December 2016
Clark Fork River (Lower) Subbasin17010213

Clark Fork/Pend Oreille TMDL approved by EPA September 2000 and April 2001

Lower Clark Fork TMDL approved by EPA October 2007

Agriculture completed September 2014 
Clearwater River (South Fork) Subbasin includes Cottonwood Creek watershed17060305Cottonwood Creek TMDL approved by EPA June 2000 and March 2004

Completed April 2006

Agriculture completed March 2005, revised January 2014

 
Clearwater River Subbasin includes Hatwai Creek, Jim Ford Creek, Lindsay Creek, Lolo Creek tributaries, Potlatch River,
Winchester Lake-Lapwai Creek watersheds
17060306

Winchester Lake TMDL approved by EPA March 1999

Jim Ford Creek TMDL approved by EPA June 2000

Lindsay Creek TMDL approved by EPA June 2007

Potlatch River TMDL approved by EPA February 2009

Hatwai Creek TMDL approved by EPA December 2010

Lolo Creek Tributaries TMDL approved by EPA December 2011

Jim Ford Creek Temperature TMDL approved by EPA September 2018

Potlatch River Watershed TMDL approved by EPA July 2018

Hatwai Creek Temperature TMDL approved by EPA August 2018

Winchester Lake completed May 2000

Lindsay Creek Agriculture completed April 2008

Potlatch River revised March 2013

Jim Ford Creek Agriculture revised February 2014

Jim Ford Creek Agriculture Addendum October 2016

Potlatch River Agriculture Addendum
March 2018

Potlatch River completed October 2017
Clearwater River, North Fork (Upper) Subbasin17060307

Approved by EPA December 2003

Lake Creek Temperature TMDL approved by EPA September 2018

Under development

 
Clearwater River, North Fork (Lower) Subbasin17060308

Approved by EPA January 2003

Five-Year Review and TMDL Addendum approved by EPA November 2013

Completed May 2004

Addendum completed December 2013

See 2013 TMDL Addendum
Coeur d’Alene Lake Subbasin includes Black Lake watershed17010303

Approved by EPA July 2000

Black Lake TMDL approved by EPA August 2011

Coeur d’Alene Lake Tributaries Addendum approved by EPA November 2012

Fernan Lake Addendum approved by EPA November 2013

Completed 2002See 2011 TMDL Addendum and Update
Coeur d’Alene River (South Fork) Subbasin17010302Approved by EPA August 2003Under development 
Coeur d’Alene River (Upper/North Fork) Subbasin17010301

Approved by EPA February 2002

Addendum approved by EPA April 2014

Under developmentSee North Fork Coeur d’Alene River Subbasin Watershed Restoration Effectiveness Review – Sediment Reductions and Biological Response Document and Success Story
Curlew Valley Subbasin16020309Approved by EPA July 2019  
Goose Creek Subbasin17040211

Approved by EPA July 2004

Temperature Addendum approved by EPA April 2012

Under developmentCompleted June 2010
Hangman Creek Subbasin17010306Approved by EPA September 2007  
Henrys Fork (Upper and Lower) Subbasin17040202 17040203

Assessment completed December 1998

Addendum approved by EPA August 2010

E. Coli TMDL approved by EPA March 2021 

NA

Completed April 2010

Completed May 2017

Idaho Falls Subbasin17040201Approved by EPA November 2004Under development 
Jordan Creek Subbasin17050108Partially approved/partially disapproved by EPA April 2011  
Kootenai and Moyie Rivers Subbasins17010101 17010104 17010105

Approved by EPA January 2007

2014 Temperature TMDL Addendum approved by EPA October 2014

2019 Temperature TMDL Addendum approved by EPA June 2019

Draft completed November 2005 
Lemhi River Subbasin17060204

Approved by EPA March 2000

Addendum approved by EPA February 2013

Completed September 2001See October 2012 TMDL Addendum
Little Lost River Subbasin17040217

Approved by EPA September 2000

2015 Temperature Addendum approved by EPA January 2016

Completed February 2002Completed July 2015
Little Salmon River Subbasin17060210

Approved by EPA March 2006

Addendum approved by EPA April 2013

Completed November 2008

Agriculture Implementation Plan April 2016

Completed April 2012
Little Wood River Subbasin17040221Approved by EPA September 2005Agriculture completed March 2010 
Lochsa River Subbasin17060303

Assessment completed September 1999

Addendum submitted to EPA May 2012

Temperature TMDL approved by EPA August 2018, revised August 2020

NA 
Medicine Lodge Creek Subbasin17040215

Approved by EPA May 2003

2016 Addendum approved by EPA January 2017

Agriculture completed July 2002 
Owyhee River (Middle) Subbasin17050107

Approved by EPA February 2000

Watershed Temperature TMDLs approved by EPA July 2012

Completed February 2002

Agriculture Implementation Plan May 2017

Completed June 2009
Owyhee River (South Fork) Subbasin17050105

Approved by EPA March 2000

Watershed Temperature TMDLs approved by EPA July 2012

Agriculture Implementation Plan May 2017 
Owyhee River (Upper) Subbasin17050104

Approved by EPA March 2003

Watershed Temperature TMDLs approved by EPA July 2012

Agriculture completed October 2004

Agriculture Implementation Plan May 2017

Completed June 2009
Pahsimeroi River Subbasin17060202

Approved by EPA December 2001

Addendum approved by EPA April 2014

Agriculture completed September 2005See 2013 TMDL Addendum
Palisades Subbasin includes Fall Creek watershed17040104

Approved by EPA February 2001

Fall Creek TMDL approved by EPA April 2004

2013 Addendum and Five-Year Review approved by EPA February 2014

Rainey Creek TMDL approved by EPA July 2019

Completed August 2002See 2013 TMDL Addendum submitted to EPA June 2019
Palouse River Subbasin includes Cow Creek and Paradise Creek watersheds17060108

Paradise Creek TMDL approved by EPA February 1998

Palouse River Tributaries TMDL approved by EPA March 2005

Cow Creek TMDL approved by EPA February 2006

South Fork Palouse River TMDL approved by EPA October 2007

Cow Creek TMDL Addendum approved
by EPA April 2014

Paradise Creek TMDL 2015 Bacteria Addendum approved by EPA November 2016

Palouse River Subbasin 2017 Temperature TMDL approved by EPA August 2017

Paradise Creek completed December 1999

Cow Creek Agriculture revised May 2013

Cow Creek Temperature July 2014

Palouse River Agriculture Addendum July 2016

Completed December 2015
Payette River (Middle Fork) Subbasin17050121

Approved by EPA July 2000

Temperature TMDL approved by EPA December 2007

Completed August 2003Completed February 2009
Payette River (North Fork) Subbasin includes Cascade Reservoir watershed17050122 17050123

Cascade Reservoir Phase I approved by EPA May 1996

Cascade Reservoir Phase II approved by EPA April 1999

North Fork Payette River TMDL approved by EPA August 2005

Cascade Reservoir Tributary Addendum approved by EPA February 2012

 

Cascade Reservoir all phases completed June 2000

North Fork Payette River
Completed June 2007

Cascade Reservoir all phases
completed February 2009

North Fork Payette River completed July 2012

Cascade Reservoir Watershed completed February 2018

Payette River (South Fork) Subbasin17050120Assessment completed July 2005NA

Completed January 2011

Payette River Subbasin includes Bissel Creek watershed17050122

Lower Payette River TMDL approved by EPA May 2000

Bissel Creek TMDL approved by EPA October 2003

Big Willow Creek Addendum approved by EPA July 2008

Little Willow Creek Addendum approved by EPA December 2013

Completed January 2003

Big Willow completed August 2010

Bissel Creek completed April 2006, revised 2014

Little Willow completed June 2014

Completed February 2010
Pend Oreille Lake Subbasin17010214

Clark Fork-Pend Oreille TMDL approved by EPA September 2000 and April 2001

Nearshore Waters TMDL approved by EPA October 2002

Temperature TMDL Addendum approved by EPA April 2008

Sediment TMDL Addendum approved by EPA January 2008

Pack River Nutrients TMDL Addendum approved by EPA December 2008

Nearshore Waters completed December 2004

Pack River completed July 2006

Cocolalla Lake, Cocolalla Creek, and Hoodoo Creek completed July 2004

Completed June 2015

Pend Oreille Lake and River Tributaries completed April 2017

Portneuf River Subbasin17040208

Approved by EPA April 2001

Revision and Addendum approved by EPA August 2010

Updated June 2020See Revised TMDL
Priest River Subbasin17010215

Approved by EPA March 2002

Addendum approved by EPA June 2003

2016 Temperature Addendum approved by EPA May 2019

Under development

 
Raft River Subbasin17040210

Approved by EPA July 2004

Temperature Addendum approved by EPA April 2012

Agriculture completed July 2006

Completed September 2011
Salmon Falls Creek Subbasin17040213

Mid-Snake River TMDL approved by EPA April 1997

Mid-Snake River TMDL Modification approved by EPA 2005

Salmon Falls Creek TMDL approved by EPA February 2008

Upper Snake Rock June 2001

Agriculture completed February 2009

 
Salmon River (Lower) and Hells Canyon Subbasins17060209 17060101

Approved by EPA February 2010

  
Salmon River (Middle) – Chamberlain Creek Subbasin17060207

Approved by EPA January 2003

Under development

2017 Temperature TMDL and Five-Year Review approved by EPA August 2017
Salmon River (Middle) – Panther Creek Subbasin17060203

Approved by EPA July 2001

Completed November 2002 
Salmon River (South Fork) Subbasin17060208

Approved by EPA January 1992

Addendum approved by EPA October 2012

Under development

Completed March 2011

Salmon River (Upper and Lower Middle Forks) Subbasin17060205 17060206

Approved by EPA February 2009

  
Salmon River (Upper) Subbasin17060201

Approved by EPA March 2003

2016 Addendum and Five-Year Review approved by EPA December 2016

Agriculture completed February 2007

 
Salt River Subbasin170401052015 E. coli TMDL approved by EPA January 2018 and August 2018Agriculture completed July 2020 
Selway River (Lower) Subbasin17060302Subbasin assessment December 2000NA 
Snake (Lower)-Asotin Subbasin includes Tammany Creek watershed17060103

Approved by EPA February 2002

Addendum approved by EPA December 2010

Under development

 
Snake River – Hells Canyon Subbasins17060101 17050103 17050115 17050201Approved by EPA September 2004See TMDL for Implementation Strategies 
Snake River (Middle) – Succor Creek Subbasin17050103

Approved by EPA January 2004

Addendum approved by EPA December 2007

Tributaries Sediment TMDL Addendum approved by EPA October 2013

Completed July 2005, revised 2014

Completed September 2011
Snake River (Upper Snake-Rock) Subbasin17040212

Mid-Snake TMDL Phase I approved by EPA April 1997

Upper Snake Rock TMDL approved by EPA August 2000

Upper Snake Rock TMDL Modification approved by EPA September 2005

City of Twin Falls TSS Revision approved by EPA March 2011

Completed June 2001

Completed April 2010

Spokane River (Upper) Subbasin17010305

Approved by EPA January 2001

Fish Creek Watershed Assessment and TMDLs approved by EPA June 2008

Under development

 
St. Joe River Subbasin includes St. Maries River watershed17010304

Approved by EPA August 2003

Temperature TMDL Addendum approved by EPA December 2011

Agriculture completed November 2003

Completed September 2011
Teton River Subbasin17040204

Approved by EPA February 2003, September 2003, February 2017

Agriculture completed April 2005, revised February 2014

 
Walcott Lake Subbasin17040209

Approved by EPA June 2000

Fall and Rueger Springs Creeks Aquaculture Addendum TMDLs approved by EPA March 2007

Lake Walcott TMDL 2013 Addendum: Marsh Creek approved by EPA January 2015

Completed December 2001

Completed May 2012

Completed October 2019

Weiser River Subbasin17050124

Approved by EPA January 2007

Temperature Addendum approved by EPA January 2007

Agriculture revised May 2013Completed June 2014
Willow Creek Subbasin17040205Approved by EPA June 2004Agriculture completed January 2011 

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Water Quality Coordinator

Graham Freeman
Graham.Freeman@deq.idaho.gov
(208) 373-0461

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