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Title 35: Environmental Protection

Subtitle C: Water Pollution

Chapter 1: Pollution Control Board

Part 302: Water Quality Standards

Sections 302.105 and 302.521

Effective August 9, 2006

Section 302.105 Antidegradation

The purpose of this Section is to protect existing uses of all waters of the State of Illinois, maintain the quality of waters with quality that is better than water quality standards, and prevent unnecessary deterioration of waters of the State.

1. Existing Uses
   Uses actually attained in a surface water body or water body segment on or after November 28, 1975, whether or not they are included in the water quality standards, must be maintained and protected. Examples of degradation of existing uses of the waters of the State include:
   1. an action that would result in the deterioration of the existing aquatic community, such as a shift from a community of predominantly pollutant-sensitive species to pollutant-tolerant species or a loss of species diversity;
   2. an action that would result in a loss of a resident or indigenous species whose presence is necessary to sustain commercial or recreational activities; or
   3. an action that would preclude continued use of a surface water body or water body segment for a public water supply or for recreational or commercial fishing, swimming, paddling or boating.
2. Outstanding Resource Waters
   1. Waters that are designated as Outstanding Resource Waters (ORWs) pursuant to 35 Ill. Adm. Code 303.205 and listed in 35 Ill.
      
      Adm. Code 303.206 must not be lowered in quality except as provided below:
      1. Activities that result in short-term, temporary (i.e., weeks or months) lowering of water quality in an ORW; or
      2. Existing site stormwater discharges that comply with applicable federal and State stormwater management regulations and do not result in a violation of any water quality standards.
   2. Any activity in subsection (b)(1)(A) or (b)(1)(B) that requires a National Pollutant Discharge Elimination System (NPDES) or a Clean Water Act (CWA) Section 401 certification must also comply with subsection (c)(2).
   3. Any activity listed in subsection (b)(1) or any other proposed increase in pollutant loading to an ORW must also meet the following requirements:
      1. All existing uses of the water will be fully protected; and
      2. Except for activities falling under one of the exceptions provided in subsection (b)(1)(A) or (B) above:
         1. The proposed increase in pollutant loading is necessary for an activity that will improve water quality in the ORW; and
         2. The improvement could not be practicably achieved without the proposed increase in pollutant loading.
   4. Any proposed increase in pollutant loading requiring an NPDES permit or a CWA 401 certification for an ORW must be assessed pursuant to subsection (f) to determine compliance with this Section.
3. High Quality Waters
   1. Except as otherwise provided in subsection (d) of this Section, waters of the State whose existing quality is better than any of the established standards of this Part must be maintained in their present high quality, unless the lowering of water quality is necessary to accommodate important economic or social development.
   2. The Agency must assess any proposed increase in pollutant loading that necessitates a new, renewed or modified NPDES permit or any activity requiring a CWA Section 401 certification to determine compliance with this Section. The assessment to determine compliance with this Section must be made on a case-by-case basis. In making this assessment, the Agency must:
      1. Consider the fate and effect of any parameters proposed for an increased pollutant loading.
      2. Assure the following:
         1. The applicable numeric or narrative water quality standard will not be exceeded as a result of the proposed activity;
         2. All existing uses will be fully protected;
         3. All technically and economically reasonable measures to avoid or minimize the extent of the proposed increase in pollutant loading have been incorporated into the proposed activity; and
         4. The activity that results in an increased pollutant loading will benefit the community at large.
      3. Utilize the following information sources, when available:
         1. Information, data or reports available to the Agency from its own sources;
         2. Information, data or reports supplied by the applicant;
         3. Agency experience with factually similar permitting scenarios; and
         4. Any other valid information available to the Agency.
4. Activities Not Subject to a Further Antidegradation Assessment
   The following activities will not be subject to a further antidegradation assessment pursuant to subsection (c) of this Section.
   1. Short-term, temporary (i.e., weeks or months) lowering of water quality;
   2. Bypasses that are not prohibited at 40 CFR 122.41(m);
   3. Response actions pursuant to the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), as amended, corrective actions, pursuant to the Resource Conservation and Recovery Act (RCRA), as amended, or similar federal or State authority, taken to alleviate a release into the environment of hazardous substances, pollutants or contaminants which may pose a danger to public health or welfare;
   4. Thermal discharges that have been approved through a CWA Section 316(a) demonstration;
   5. New or increased discharges of a non-contact cooling water:
      1. without additives, except as provided in subsection (d)(5)(B), returned to the same body of water from which it was taken, as defined by 35 Ill. Adm. Code 352.104, provided that the discharge complies with applicable Illinois thermal standards; or
      2. containing chlorine when the non-contact cooling water is treated to remove residual chlorine, and returned to the same body of water from which it was taken, as defined in 35 Ill. Adm. Code 352.104, provided that the discharge complies with applicable Illinois thermal and effluent standards at 35 Ill. Adm. Code 302, 303, and 304;
   6. Discharges permitted under a current general NPDES permit as provided by 415 ILCS 5/39(b) or a nationwide or regional CWA Section 404 permit are not subject to facility-specific antidegradation review; however, the Agency must assure that individual permits or certifications are required prior to all new pollutant loadings or hydrological modifications that necessitate a new, renewed or modified NPDES permit or CWA Section 401 certification that affects waters of particular biological significance. Waters of particular biological significance may include streams listed in a 1991 publication by the Illinois Department of Conservation entitled "Biologically Significant Illinois Streams"; or
   7. Changes to or inclusion of a new permit limitation that does not result in an actual increase of a pollutant loading, such as those stemming from improved monitoring data, new analytical testing methods, new or revised technology or water quality based effluent limits.
5. Lake Michigan Basin
   Waters in the Lake Michigan basin as identified in 35 Ill. Adm. Code 303.443 are also subject to the requirements applicable to bioaccumulative chemicals of concern found at Section 302.521 of this Part.
6. Antidegradation Assessments
   In conducting an antidegradation assessment pursuant to this Section, the Agency must comply with the following procedures.
   1. A permit application for any proposed increase in pollutant loading that necessitates the issuance of a new, renewed, or modified NPDES permit or a CWA Section 401 certification must include, to the extent necessary for the Agency to determine that the permit application meets the requirements of this Section, the following information:
      1. Identification and characterization of the water body affected by the proposed load increase or proposed activity and the existing water body’s uses. Characterization must address physical, biological and chemical conditions of the water body.
      2. Identification and quantification of the proposed load increases for the applicable parameters and of the potential impacts of the proposed activity on the affected waters.
      3. The purpose and anticipated benefits of the proposed activity. Such benefits may include:
         1. Providing a centralized wastewater collection and treatment system for a previously unsewered community;
         2. Expansion to provide service for anticipated residential or industrial growth consistent with a community’s long range urban planning;
         3. Addition of a new product line or production

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Section 302.521 Supplemental Antidegradation Provisions for BCCs

1. Notwithstanding the provisions of Section 302.105, waters within the Lake Michigan Basin must not be lowered in quality due to new or increased loading of substances defined as bioaccumulative chemicals of concern (BCCs) in Section 302.501 from any source or activity subject to the NPDES permitting, Section 401 water quality certification provisions of the Clean Water Act (P.L. 92-100, as amended), or joint permits from the Agency and the Illinois Department of Natural Resources under Section 39(n) of the Act [415 ILCS 5/39(n)] until and unless it can be affirmatively demonstrated that such change is necessary to accommodate important economic or social development.
   1. Where ambient concentrations of a BCC are equal to or exceed an applicable water quality criterion, no increase in loading of that BCC is allowed.
   2. Where ambient concentrations of a BCC are below the applicable water quality criterion, a demonstration to justify increased loading of that BCC must include the following:
      1. Pollution Prevention Alternatives Analysis. Identify any cost-effective reasonably available pollution prevention alternatives and techniques that would eliminate or significantly reduce the extent of increased loading of the BCC.
      2. Alternative or Enhanced Treatment Analysis. Identify alternative or enhanced treatment techniques that are cost effective and reasonably available to the entity that would eliminate or significantly reduce the extent of increased loading of the BCC.
      3. Important Social or Economic Development Analysis. Identify the social or economic development and the benefits that would be forgone if the increased loading of the BCC is not allowed.
   3. In no case shall increased loading of BCCs result in exceedence of applicable water quality criteria or concentrations exceeding the level of water quality necessary to protect existing uses.
   4. Changes in loadings of any BCC within the existing capacity and processes of an existing NPDES authorized discharge, certified activity pursuant to Section 401 of the Clean Water Act, or joint permits from the Agency and the Illinois Department of Natural Resources under Section 39(n) of the Act are not subject to the antidegradation review of subsection (a) of this Section. These changes include but are not limited to:
      1. normal operational variability, including, but not limited to, intermittent increased discharges due to wet weather conditions;
      2. changes in intake water pollutants;
      3. increasing the production hours of the facility; or
      4. increasing the rate of production.
   5. Any determination to allow increased loading of a BCC pursuant to a demonstration of important economic or social development need shall satisfy the public participation requirements of 40 CFR 25 prior to final issuance of the NPDES permit, Section 401 water quality certification, or joint permits from the Agency and the Illinois Department of Natural Resources under Section 39(n) of the Act.
2. The following actions are not subject to the provisions of subsection (a) of this Section, unless the Agency determines the circumstances of an individual situation warrant application of those provisions to adequately protect water quality:
   1. Short-term, temporary (i.e., weeks or months) lowering of water quality;
   2. Bypasses that are not prohibited at 40 CFR 122.41 (m); or
   3. Response actions pursuant to the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), as amended, or similar federal or State authority, undertaken to alleviate a release into the environment of hazardous substances, pollutants or contaminants that pose danger to public health or welfare.

(Source: Amended at 23 Ill. Reg. 11249, effective August 26, 1999)

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