303d list

The Agency has prepared a list of impaired waters to fulfill the requirements set forth in Section 303(d) of the federal Clean Water Act and the Water Quality Planning and Management regulation at 40 CFR Part 130. The report also provides information about the Total Maximum Daily Load program/process in Illinois.

Illinois EPA (IEPA) submitted its 2024 Section 303(d) list to the U.S. EPA on October 2, 2024, with additional information submitted on October 30, 2024. U.S. EPA evaluated IEPA’s submission and determined that it was not fully consistent with the requirements of Section 303(d) of the CWA and the U.S. EPA’s implementing regulations. On December 11, 2024, U.S. EPA partially approved and partially disapproved IEPA’s 2024 303(d) list submission.  USEPA disapproval was for 19 waterbody segments, because data and information submitted indicated that the aesthetic quality use was not being met for algae for these impaired waterbodies and did not identify total phosphorous as a contributing cause.

U.S. EPA issued a public notice (December 17, 2024 -January 31, 2025), for public comment on its identification of 19 Water Quality Limited Segments (WQLS) impaired by total phosphorus to be included on IEPA’s 2024 List of Impaired Waters under Section 303(d) of the Clean Water Act.

USEPA has placed the waterbodies back on Category 5 as no additional comments were received during the public notice period, and the waterbodies will be addressed in the 2026 IR Cycle.

For additional information on U.S. EPA’s partial disapproval decision for IEPA’s 2024 303(d) list, refer to Section 2.D.iv of the Decision Document below.

• Transmittal Letter for USEPA’s Final Action on Illinois' 2024 Section 303(d) List (pdf) following (December 2024) - public notice
• First Transmittal Letter for USEPA Action on Illinois' 2024 Section 303(d) List (pdf) (12/11/2024)
• USEPA Decision Document for Illinois’ 2024 Section 303(d) List (pdf) (12/11/2024)
• Appendix 1 (pdf) (December 2024) USEPA Approved Illinois 2024 303(d) List of Impaired Waters Needing TMDLs.
• Appendix 2 (pdf) (December 2024) Waterbody Segments/Pollutants Removed from the Illinois’ Approved 2020/2022 303(d) List.
• Appendix 3 (pdf) (December 2024) Water Quality Limited Segments the USEPA is Adding to the Illinois’ 2024 303(d) List for Total Phosphorus.
• Appendix 4 (pdf) (December 2024) Illinois Environmental Protection Agency. Illinois 2024 Integrated Report Appendix E—Responsiveness Summary.
• Appendix 5: Illinois Algae and Total Phosphorus Data for Waters with Algae Impairments in Category 4C Without a Pollutant in Category 5
  • Appendix 5 - Table 1 (pdf) (December 2024) Algae Data.
  • Appendix 5 - Table 2 (pdf) (December 2024) Total Phosphorus Data.
• Appendix 6 (pdf) (December 2024) Illinois Cyanotoxin Data, 2017-2021.

• 2020/2022 Integrated Report Public Notice and Comment Period (February 14, 2022 to March 16, 2022)
• 2020/2022 Integrated Report Transmittal Letter from Illinois EPA to USEPA

Final as submitted to USEPA, Region 5 on June 1, 2022

• Illinois Integrated Water Quality Report and Section 303(d) List – 2020/2022
• Appendix A-1. Specific Assessment Information for Streams, 2020/2022
• Appendix A-2. Specific Assessment Information for Lakes, 2020/2022
• Appendix A-3. Specific Assessment Information for Lake Michigan, 2020/2022
• Appendix A-4. Statewide Resource Quality Summary for Significant Publicly Owned Lakes, 2020/2022
• Appendix B-1. Using Large Continuous Monitoring Datasets to Assess Attainment of Aquatic Life Use at Some Illinois Stream Sites
• Appendix B-2. A New Method to Apply Chronic Water Quality Standards When Assessing Attainment of Aquatic Life Uses in Illinois Waters
• Appendix B-3. Total Nitrogen, Sedimentation/Siltation, and Other Non-Standards-Based Pollutants as Causes of Use Impairment in the Integrated 305(b)/303(d) Water Quality Report
• Appendix B-4. Data Packages Submitted to Illinois EPA for Consideration in Preparing the 2020/2022 Integrated Report
• Appendix C-1. 303(d) List (In Priority Order)
• Appendix C-2. 303(d) List (In Alphabetical Order)
• Appendix C-3. Illinois Two Year Schedule for TMDL Development, 2022 - 2024
• Appendix C-4. Segments/Causes Removed From Illinois' 2018 Section 303(d) List
• Appendix C-5. Long-term Vision for Assessment, Restoration and Protection under the Clean Water Act Section 303(d) Program, January 2022
• Appendix C-6. Status of TMDL Development in Illinois
• Appendix C-7. Illinois Waters in Category 4C (Impairment not caused by pollutants)
• Appendix C-8. 2020/2022 303(d) Listed Waters Maps
• Appendix D. Changes in Assessment Unit IDs Between 2018 and 2022
• Appendix E. Responsiveness Summary

USEPA approval of the 2020/2022 Integrated Report on June 30, 2022

• USEPA Approval Letter
• USEPA Decision Document

• 2018 Integrated Report Original Public Notice and Comment Period (June 15 to July 16, 2018)
• Second Public Notice and Comment Period (May 9, to May 24, 2019) on Revisions to Use-Attainment Determinations and Caues of Impairment
• Revisions of Selected Assessment Units for Cycle 2018 Integrated Report
• 2018 Integrated Report Transmittal Letter from Illinois EPA to USEPA

Final as submitted to USEPA, Region 5 on February 22, 2021

• llinois Integrated Water Quality Report and Section 303(d) List – 2018
• Appendix A-1. 303(d) List (In Priority Order)
• Appendix A-2. 303(d) List (In Alphabetical Order)
• Appendix A-3. Illinois Two Year Schedule for TMDL Development, 2018 - 2020
•  Appendix A-4. Segments/Causes Removed From Illinois' 2016 303(d) List
• Appendix A-5. Long-term Vision for Assessment, Restoration and Protection under Section 303(d) Program
• Appendix A-6. Status of TMDL Development in Illinois
• Appendix A-7. Illinois Waters in Category 4C (Impairment not caused by pollutants)
• Appendix B-1. Illinois EPA Basins
• Appendix B-2. Specific Assessment Information for Streams, 2018
• Appendix B-3. Specific Assessment Information for Lakes, 2018
• Appendix B-4. Specific Assessment Information for Lake Michigan Waters, 2018
• Appendix C. Statewide Resource Quality Summary For Significant Publicly Owned Lakes, 2018
• Appendix D. Form for Evaluating Compliance with Offensive Conditions
• Appendix E. Changes in Assessment Unit IDs
• Appendix F. Responsiveness Summary
• Appendix G. Total Nitrogen, Sedimentation/Siltation, and Other Non-Standards-Based Pollutants as Causes of Use Impairment in the Integrated 305(b)/303(d) Water Quality-Report

USEPA approval of the 2018 Integrated Report on March 19, 2021

• USEPA Approval Letter
• USEPA Decision Document
• Table 1.  Waters and Impairments Approved on Illinois’ 2018 303(d) List
• Table 2.  Waters and Impairments Added to Illinois’ 2018 303(d) List
• Table 3.  Waters and Impairments Removed from Illinois’ 2016 303(d) List

• 2016 Integrated Report Public Notice
• 2016 Integrated Report Transmittal Letter

Final as submitted to USEPA, Region 5 on July 11, 2016

• Illinois Integrated Water Quality Report and Section 303(d) List - Volume I: Surface Water - 2016
• Appendix A-1. 303(d) List (In Priority Order)
• Appendix A-2. 303(d) List (In Alphabetical Order)
• Appendix A-3. Illinois Two Year Schedule for TMDL Development, 2016 - 2018
• Appendix A-4. Segments/Causes Removed From Illinois' 2014 303(d) List
• Appendix A-5. 2016 303(d) Listed Waters Maps
• Appendix A-6. Status of TMDL Development in Illinois
• Appendix A-7. Illinois EPA Projects in TMDL Watersheds
• Appendix A-8. Illinois Waters in Category 4C (Impairment not caused by pollutants).
• Appendix B-1. Illinois EPA Basins
• Appendix B-2. Specific Assessment Information for Streams, 2016
• Appendix B-3. Specific Assessment Information for Inland Lakes, 2016
• Appendix B-4. Specific Assessment Information for Lake Michigan Waters, 2016
• Appendix C. Statewide Resource Quality Summary For Significant Publicly Owned Lakes, 2016
• Appendix D. Changes in Assessment Unit IDs Between 2014 and 2016
• Appendix E. Form for evaluating compliance with Offensive Conditions
• Appendix F. Long-term Vision for Assessment, Restoration and Protection under Section 303(d) of the Clean Water Act, September 16, 2015
• Appendix G. Responsiveness Summary, July 11, 2016
• Illinois Integrated Water Quality Report and Section 303(d) List - Volume II: Groundwater - 2016
• Groundwater Appendix A - Source Water Data for 2016 Groundwater Use Assessments

• 2014 Integrated Report Notice of Public Hearing
• 2014 Integrated Report Transmittal Letter

Final as submitted to USEPA, Region 5 on March 24, 2014

• Illinois Integrated Water Quality Report and Section 303(d) List - Volume I: Surface Water - 2014       
• Appendix A-1. 303(d) List (In Priority Order)
• Appendix A-2. 303(d) List (In Alphabetical Order)
• Appendix A-3. Illinois Two Year Schedule for TMDL Development, 2014 - 2016
• Appendix A-4. Segments/Causes Removed From Illinois' 2012 303(d) List
• Appendix A-5. 2014 Illinois Water Quality Maps 
• Appendix A-6. Status of TMDL Development in Illinois
• Appendix A-7. Illinois EPA Projects in TMDL Watersheds
• Appendix A-8. Illinois Waters in Category 4C (Impairment not caused by pollutants)
• Appendix B-1. Illinois EPA Basins
• Appendix B-2. Specific Assessment Information for Streams, 2014
• Appendix B-3. Specific Assessment Information for Inland Lakes, 2014
• Appendix B-4. Specific Assessment Information for Lake Michigan Waters, 2014
• Appendix C. Statewide Resource Quality Summary For Significant Publicly Owned Lakes, 2014
• Appendix D. Changes in Assessment Unit IDs Between 2012 and 2014
• Appendix E. Form for evaluating compliance with Offensive Conditions
• Appendix F. Responsiveness Summary, March 24, 2014
• Illinois Integrated Water Quality Report and Section 303(d) List - Volume II: Groundwater - 2014
  • Groundwater Appendix A. Source Water Data for 2014 Groundwater Use Assessments

• 2012 Integrated Report Notice of Public Hearing
• 2012 Integrated Report Transmittal Letter

Final as submitted to USEPA, Region 5 on December 20, 2012

• Illinois Integrated Water Quality Report and Section 303(d) List - Volume I: Surface Water - 2012
• Appendix A-1. 303(d) List (In Priority Order)
• Appendix A-2. 303(d) List (In Alphabetical Order)
• Appendix A-3. Illinois Two Year Schedule for TMDL Development, 2012 - 2014
• Appendix A-4. Segments/Causes Removed From Illinois' 2010 303(d) List
• Appendix A-5. 2012 Illinois EPA Waters
• Appendix A-6. Status of TMDL Development in Illinois
• Appendix A-7. Illinois EPA Projects in TMDL Watersheds
• Appendix A-8. Illinois Waters in Category 4C (Impairment not caused by pollutants)
• Appendix B-1. Illinois EPA Basins
• Appendix B-2. Specific Assessment Information for Streams, 2012
• Appendix B-3. Specific Assessment Information for Inland Lakes, 2012
• Appendix B-4. Specific Assessment Information for Lake Michigan Waters, 2012
• Appendix C. Statewide Resource Quality Summary For Significant Publicly Owned Lakes, 2012
• Appendix D. Changes in Assessment Unit IDs Between 2010 and 2012
• Appendix E. Form for Evaluating Compliance with Offensive Conditions
• Appendix F. Responsiveness Summary
• Illinois Integrated Water Quality Report and Section 303(d) List - Volume II: Groundwater - 2012
• Groundwater Appendix A. Source Water Data for 2012 Groundwater Use Assessments

• 2010 Integrated Report Transmittal Letter

Final as submitted to USEPA, Region 5 on December 23, 2011       

• Illinois Integrated Water Quality Report and Section 303(d) List - Volume I - Surface Water - 2010
• Appendix A-1. Category 5 - 303(d) List (In Priority Order)
• Appendix A-2. Category 5 - 303(d) List (In Alphabetical Order)
• Appendix A-3. Illinois Two Year Schedule for TMDL Development, 2010 - 2012
• Appendix A-4. Segments/Causes Removed From Illinois' 2008 303(d) List
• Appendix A-6. Status of TMDL Development in Illinois, 2010
• Appendix A-7. Illinois EPA Projects in TMDL Watersheds
• Appendix B-1. Illinois EPA Basins
• Appendix B-2. Specific Assessment Information for Streams, 2010
• Appendix B-3. Specific Assessment Information for Inland Lakes, 2010
• Appendix B-4. Specific Assessment Information for Lake Michigan Open Waters, 2010
• Appendix B-5. Specific Assessment Information for Lake Michigan Beaches, 2010
• Appendix B-6. Specific Assessment Information for Lake Michigan Bays and Harbors, 2010
• Appendix C. Statewide Resource Quality Summary For Significant Publicly Owned Lakes, 2010
• Appendix D. Changes in Assessment Unit IDs Between 2008 and 2010
• Appendix E. Responsiveness Summary
• Illinois Integrated Water Quality Report and Section 303(d) List - Volume II - Groundwater - 2010
• Groundwater Appendix A. Source Water Data for 2010 Groundwater Use Assessments

• Illinois EPA Response to December 29, 2008, Federal Register Notice
  • February 11, 2009, Cover Letter from Marcia Willhite, Illinois EPA, to Timothy Henry, USEPA Region 5
  • February 11, 2009, Illinois EPA Comments on USEPA’s Partial Disapproval of Illinois’ 2008 303(d) List and USPEA’s Proposed 303(d) List for Illinois
  • Attachment A – USEPA October 22, 2008, Decision Document Cover Letter
  • Attachment B – USEPA October 22, 2008, Decision Document
  • Attachment C – USEPA December 12, 2008, Approval of Illinois EPA Revised Dissolved Oxygen Standard
  • Attachment D – Illinois Attorney General’s Office Letter to USEPA Certifying Illinois EPA’s Revised Water Quality Standards for Sulfates and Total Dissolved Solids
  • Attachment E – Illinois EPA Response to USEPA Decision Document Tables 1-5
  • Attachment F – USEPA Evaluation of Illinois EPA 75% - Silt/Mud Guideline to Identify Sedimentation/Siltation as a Cause of Impairment
  • Attachment G – Illinois EPA Technical Review of USEPA Evaluation of the 75% - Silt/Mud Guideline Used by Illinois EPA
• USEPA, Region 5, is seeking comments on proposed additions (and on one deletion) to the Illinois 2008 303(d) List through February 12, 2009.
• View Federal Register Notice
  
  (December 29, 2008)
• USEPA Partial Approval Partial Disapproval Illinois 2008 303d List
  
  (October 22, 2008)
  • USEPA Decision Document
  • Waters delisted based on New Dissolved Oxygen Standard
    
    (Note that USEPA, Region 5, approved this standard on December 18, 2008)
  • Waters delisted based on Deletion of General Use TDS Standard
    
    (Note that USEPA, Region 5, approved this standard on March 19, 2009)
  • Waters delisted based on New Sulfate General Use Water Quality Standard
    
    (Note that USEPA, Region 5, approved this standard on March 19, 2009)
  • Waters delisted for Total Nitrogen Impairment due to methodology change
  • Waters delisted for Sedimentation Impairment due to methodology change
  • Waters listed as DO Impaired (with DO as a non-pollutant)
  • Partially Approved 2008 Illinois 303(d) List

Final as submitted to USEPA, Region 5 on June 30, 2008 

• Illinois Integrated Water Quality Report and Section 303(d) List - 2008
• Appendix A-1. 303(d) List
• Appendix A-2. Look-up Index to 2008 303(d) List
• Appendix A-3. Two year schedule for TMDL Development
• Appendix A-4. Delisting of Segment/Causes from the 2006 303(d) List
• Appendix A-6. Status of TMDLs in Development in Illinois
• Appendix A-7. Illinois EPA Projects in TMDL Waterbodies
• Appendix B-1. Illinois' EPA Basins
• Appendix B-2. Specific Assessment Information for Streams
• Appendix B-3. Specific Assessment Information for Inland Lakes
• Appendix B-4. Specific Assessment Information for Lake Michigan Open Waters
• Appendix B-5. Specific Assessment Information for Lake Michigan Beaches
• Appendix B-6. Specific Assessment Information for Lake Michigan Bays and Harbors
• Appendix C. Statewide Resource Quailty Summary For Significant Publicly Owned Lakes
• Appendix D. Changes in Assessment Uint IDs between 2006 and 2008
• Appendix E. Groundwater Use Assessments
• Appendix F. Responsiveness Summary

• Illinois Integrated Water Quality Report and Section 303(d) List - 2006
• Appendix A. Illinois' 2006 303(d) List (Catagory 5 Impaired Waters) 
• Appendix A Look-up Index
• Appendix B. Waterbody Specific Assessment Information for Illinois-2006
• B-1. Stream Assessments 
• B-2. Lake Assessments
• B-3-B-5. Lake Michigan Assessments
• Appendix C. Translation Table for 2004 WBID/Segment ID to 2006 Assesment Unit ID
• Appendix D. Statewide Resource Quality Summary for Significant Publicly Owned Lakes
• Appendix E. Groundwater Assessments 
• Appendix F. Responsiveness Summary
• Appendix G. Watershed Maps 
• Appendix H. USEPA Approval Letter and Decision Document

• Illinois 2004 Section 303(d) List
• Appendices
• Listed Waters Maps

• Guidance for Submittal of Surface Water Data
• Illinois Water Quality Section 305(b) Report - 2004