# 35 Ill. Adm. Code 203.207: Section 203.207 Major Modification of a Source > Illinois · Regulations · In force URL: https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_207 ## Section - **Citation:** 35 Ill. Adm. Code 203.207 - **Heading:** Section 203.207 Major Modification of a Source - **Jurisdiction:** Illinois - **Kind:** Regulations - **Status:** In force - **Text as of:** August 14, 2026 - **Source:** Compiled text - **Location:** Illinois Administrative Code / Title 35 ENVIRONMENTAL PROTECTION / CHAPTER I: POLLUTION CONTROL BOARD / Part 203 MAJOR STATIONARY SOURCES CONSTRUCTION AND MODIFICATION / Section 203.207 Major Modification of a Source ## Text Section 203 Section 203.207  Major Modification of a Source a)         Except as provided in subsection (c), (d), (e) or (f), a physical change, or change in the method of operation of a major stationary source that would result in a significant net emissions increase of any pollutant for which the area is designated a nonattainment area, shall constitute a major modification of a source. b)         Any net emissions increase that is significant for volatile organic material or nitrogen oxides shall be considered significant for ozone. c)         A physical change or change in the method of operation shall not include: 1)         Routine maintenance and repair. 2)         Use of an alternative fuel or raw material by reason of any order under Section 2(a) and (b) of the Energy Supply and Environmental Coordination Act of 1974 (15 USC 791), the Power Plant and Industrial Fuel Use Act of 1978 (42 USC 8301) (or any superseding legislation) or by reason of a natural gas curtailment plan under the Federal Power Act (16 USC 791, et seq.). 3)         Use of an alternative fuel by reason of an order or rule under Section 125 of the Clean Air Act (42 USC 7425). 4)         Use of an alternative fuel at a steam generating unit to the extent that the fuel is generated from municipal solid waste. 5)         Use of an alternative fuel or raw material by a stationary source that: A)        Was capable of accommodating such alternative fuel or raw material before December 21, 1976, and that has continuously remained capable of accommodating such fuels or materials unless such change would be prohibited under any enforceable permit condition established after December 21, 1976, under 40 CFR 52.21, 35 Ill. Adm. Code 204, this Part, or 35 Ill. Adm. Code 201.142 or 201.143; or B)        Is approved for use under any permit issued under this Part or 35 Ill. Adm. Code 201.142 or 201.143 s continuously remained capable of accommodating such fuels or materials unless such change would be prohibited under any enforceable permit condition established after December 21, 1976, under 40 CFR 52.21, 35 Ill. Adm. Code 204, this Part, or 35 Ill. Adm. Code 201.142 or 201.143; or B)        Is approved for use under any permit issued under this Part or 35 Ill. Adm. Code 201.142 or 201.143. 6)         An increase in the hours of operation or in the production rate, unless such change is prohibited under any enforceable permit condition that was established after December 21, 1976 under 40 CFR 52.21, 35 Ill. Adm. Code 204, this Part, or 35 Ill. Adm. Code 201.142 or 201.143. 7)         Any change in ownership at a stationary source. d)         In an area classified as serious or severe nonattainment for ozone, increased emissions of volatile organic material or nitrogen oxides resulting from any physical change in, or change in the method  of operation of, a stationary source located in the area shall be considered de minimis for purposes of this Part if the increase in net emissions of such air pollutant from such source does not exceed 25 tons when aggregated with all other net increases in emissions from the source over any period of five consecutive calendar years that includes the year in which such increase occurred. e)         In the case of any major stationary source of volatile organic material or nitrogen oxides located in an area classified as serious or severe nonattainment for ozone (other than a source that emits or has the potential to emit 100 tons or more of volatile organic material or nitrogen oxides per year), whenever any change at that source results in any increase (other than a de minimis increase) in emissions of volatile organic material or nitrogen oxides, respectively, from any discrete operation, unit, or other pollutant emitting activity at the source, such increase shall be considered a major modification for purposes of this Part, except such increase shall or nitrogen oxides per year), whenever any change at that source results in any increase (other than a de minimis increase) in emissions of volatile organic material or nitrogen oxides, respectively, from any discrete operation, unit, or other pollutant emitting activity at the source, such increase shall be considered a major modification for purposes of this Part, except such increase shall not be considered a major modification for such purposes if the owner or operator of the source elects to offset the increase by a greater reduction in emissions of volatile organic material or nitrogen oxides, respectively, from other operations, units, or activities within the source at an internal offset ratio of at least 1.3 to 1. f)         In areas classified as extreme nonattainment for ozone, beginning on the date that an area is classified by USEPA as an extreme nonattainment area for ozone, any physical change in or change in the method of operation of a major stationary source that results in any increase in emissions of volatile organic material or nitrogen oxides from a discrete operation, unit, or other pollutant emitting activity shall be considered a major modification. ## Nearby sections - [35 Ill. Adm. Code 203.201 Section 203.201 Prohibition](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_201.md) - [35 Ill. Adm. Code 203.202 Section 203.202 Coordination with Permit Requirement and Application Pursuant to 35 Ill. Adm. Code 201](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_202.md) - [35 Ill. Adm. Code 203.203 Section 203.203 Construction Permit Requirement and Application](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_203.md) - [35 Ill. Adm. Code 203.204 Section 203.204 Duration of Construction Permit (Repealed)](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_204.md) - [35 Ill. Adm. Code 203.205 Section 203.205 Effect of Permits](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_205.md) - [35 Ill. Adm. Code 203.206 Section 203.206 Major Stationary Source](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_206.md) - [35 Ill. Adm. Code 203.207 Section 203.207 Major Modification of a Source](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_207.md) - [35 Ill. Adm. Code 203.208 Section 203.208 Net Emission Determination](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_208.md) - [35 Ill. Adm. Code 203.209 Section 203.209 Significant Emissions Determination](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_209.md) - [35 Ill. Adm. Code 203.210 Section 203.210 Relaxation of a Source-Specific Limitation](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_210.md) - [35 Ill. Adm. Code 203.211 Section 203.211 Permit Exemption Based on Fugitive Emissions](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_211.md) --- Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P203_S203_207. Check the current official text before relying on it. Not legal advice.