Water Quality Standards Regulations: Illinois
Presented are water quality standards in effect for Clean Water Act (CWA) purposes for this state.
EPA is posting these standards as a convenience to users and has made a reasonable effort to assure their accuracy. For each document listed under "State Standards in Effect for CWA Purposes", EPA has made a reasonable effort to identify parts of the standards that are disapproved or are otherwise not in effect for CWA purposes. Additionally, please note the documents may also contain provisions that EPA does not have the authority and duty to act on under the Clean Water Act because the provisions are not water quality standards.
State Standards in Effect for CWA Purposes
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Introduction - Title 35: Environmental Protection, Subtitle C: Pollution, Chapter 1: Pollution Control Board, Part 301 (pdf)
(205.96 KB)
(Effective May 28, 2013) Document contains statements of authority, policy, and definitions relative to the Illinois water quality standards. Please note that not all provisions are in effect for Clean Water Act purposes. Refer to the document cover page for more information.-
Environmental Protection, Subtitle C: Pollution, Chapter 1: Pollution Control Board, Part 301 (1999) (pdf)
(84.91 KB)
(Effective August 26, 1999)
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Environmental Protection, Subtitle C: Pollution, Chapter 1: Pollution Control Board, Part 301 (1999) (pdf)
(84.91 KB)
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Water Quality Standards - Title 35: Environmental Protection, Subtitle C: Pollution, Chapter 1: Pollution Control Board, Part 302 (pdf)
(838.76 KB)
(Effective June 24, 2019) Document contains general provisions of the Illinois water quality standards. -
Variances from Water Quality Standards (pdf)
(70.25 KB)
(Effective May 12, 2022) This table presents approved variances to the Illinois Water Quality Standards. - Derived Water Quality Criteria
These water quality criteria are derived from EPA-approved methodologies contained in Illinois' water quality standards at Section 302, Subpart F ("Procedures for Determining Water Quality Criteria"). The criteria themselves are not submitted to EPA for approval but are a numeric expression of Illinois' approved narrative criterion and translator. -
Use Designations and Site Specific Water Quality Standards - Title 35: Environmental Protection, Subtitle C: Pollution, Chapter 1: Pollution Control Board, Part 303 (pdf)
(385.58 KB)
(Effective June 24, 2019) Water use designations and site-specific water quality standards. Please note that not all provisions are in effect for Clean Water Act purposes. Refer to cover page for more information. -
Antidegradation Provisions for Bioaccumulative Chemicals of Concern – Title 35: Environmental Protection, Chapter II: Environmental Protection Agency, Part 352.900 (pdf)
(94.75 KB)
Antidegradation Provisions from Section 352.90. -
Effluent Disinfection Exemptions - Title 35: Environmental Protection, Subtitle C: Water Pollution, Chapter 1: Pollution Control Board, Part 378 (pdf)
(69.74 KB)
Document establishes requirements for determining which National Pollutant Discharge Elimination System permit dischargers may cease effluent disinfection on seasonal or year-round basis. -
Illinois Permitting Guidance for Mixing Zones (pdf)
(1.21 MB)
(March 15, 1993) Note: Illinois has decided not to adopt requirements governing the development of total maximum daily loads for the Great Lakes System consistent with the requirements in Procedure 3 in Appendix F in the Great Lakes Guidance contained at 40 CFR 132. Pursuant to the Great Lakes Guidance, EPA has determined that the federal provisions at 40 CFR 132, Appendix F, Procedure 3 shall apply.
Federally Proposed or Promulgated Standards
- 40 CFR §131.41 Bacteriological criteria for those states not complying with Clean Water Act section 303(i)(1)(A)
- 40 CFR § 132 Water Quality Guidance for the Great Lakes System
Federal Clean Water Act Determinations that New or Revised Standards Are Necessary
EPA has issued the following determinations under Clean Water Act section 303(c)(4)(B) that new or revised standards are necessary. EPA may propose federal replacement standards in these cases if the state does not adopt standards consistent with the Act.
The document suggests how states and authorized tribes can conduct online public hearings in lieu of in-person public hearings, consistent with federal public hearing requirements.