# 35 Ill. Adm. Code 6200.620.430: Section 620.430 Groundwater Quality Standards for Class III: Special Resource Groundwater

> Illinois · Regulations · In force

URL: https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P6200_S620_430

## Section

- **Citation:** 35 Ill. Adm. Code 6200.620.430
- **Heading:** Section 620.430 Groundwater Quality Standards for Class III: Special Resource Groundwater
- **Jurisdiction:** Illinois
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** August 14, 2026
- **Source:** Compiled text
- **Location:** Illinois Administrative Code / Title 35  /  / Part 6200  / Section 620.430 Groundwater Quality Standards for Class III:  Special Resource Groundwater

## Text

Section 620
TITLE 35: ENVIRONMENTAL PROTECTION
SUBTITLE F: PUBLIC WATER SUPPLIES
CHAPTER I: POLLUTION CONTROL BOARD
PART 620 GROUNDWATER QUALITY
SECTION 620.430 GROUNDWATER QUALITY STANDARDS FOR CLASS III: SPECIAL RESOURCE GROUNDWATER
Section 620.430  Groundwater
Quality Standards for Class III:  Special Resource Groundwater
Except due to natural causes,
concentrations of inorganic and organic chemical constituents and ranges of pH
must not exceed the standards specified in Section 620.410.  This prohibition
does not apply to:
a)         Chemical constituents for which the Board has adopted standards
under Section 620.260; or
b)         Class
III Special Resource Groundwater established under Section 620.230(b) and
depicted in the Environmental Register, but only at the dedicated nature
preserves identified in this subsection (b), and only for the conditions at
those preserves for which standards are specified in this subsection (b).
1)         The
following standards apply for Pautler Cave Nature Preserve and Stemler Cave
Nature Preserve (Environmental Register, May 2005, No. 611), Fogelpole Cave
Nature Preserve (Environmental Register, May 2003, No. 587), and Armin Krueger
Speleological Nature Preserve (Environmental Register, December 2009, No. 666):
Chloride
20 mg/L
pH
range of 7.0-9.0 Standard Units
2)         The
following standard applies for Cotton Creek Marsh Nature Preserve and Spring
Grove Fen Nature Preserve (Environmental Register, July 2012, No. 697):
Chloride
45 mg/L

## Nearby sections

- [35 Ill. Adm. Code 6200.620.410 Section 620.410  Groundwater Quality Standards for Class I:  Potable Resource Groundwater](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P6200_S620_410.md)
- [35 Ill. Adm. Code 6200.620.420 Section 620.420  Groundwater Quality Standards for Class II:  General Resource Groundwater](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P6200_S620_420.md)
- [35 Ill. Adm. Code 6200.620.430 Section 620.430  Groundwater Quality Standards for Class III:  Special Resource Groundwater](https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P6200_S620_430.md)

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Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P6200_S620_430. Check the current official text before relying on it. Not legal advice.