# 35 Ill. Adm. Code 6200.620.420: Section 620.420 Groundwater Quality Standards for Class II: General Resource Groundwater

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URL: https://www.frixlaw.com/law-library/statutes/STATE_IL_IAC_T35_P6200_S620_420

## Section

- **Citation:** 35 Ill. Adm. Code 6200.620.420
- **Heading:** Section 620.420 Groundwater Quality Standards for Class II: General 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 620.420 Groundwater Quality Standards for Class II:  General Resource Groundwater

## Text

Section 620
TITLE 35: ENVIRONMENTAL PROTECTION
SUBTITLE F: PUBLIC WATER SUPPLIES
CHAPTER I: POLLUTION CONTROL BOARD
PART 620 GROUNDWATER QUALITY
SECTION 620.420 GROUNDWATER QUALITY STANDARDS FOR CLASS II: GENERAL RESOURCE GROUNDWATER
Section 620.420  Groundwater
Quality Standards for Class II:  General Resource Groundwater
a)         Inorganic Chemical Constituents
1)         Except due to natural causes or as provided in Section 620.450
or subsection (a)(3) or (e) of this Section, concentrations of the following
chemical constituents must not be exceeded in Class II groundwater:
CASRN
Constituent
Standard (mg/L)
a
7440-36-0
Antimony
0.024
b
7440-38-2
Arsenic
b
0.2
d
7440-39-3
Barium
2.0
e
7440-41-7
Beryllium
0.5
f
7440-43-9
Cadmium
0.05
g
7440-47-3
Chromium (total)
1.0
g
7440-48-4
Cobalt
1
d
143-33-9
Cyanide
0.6
d
7681-49-4
Fluoride
4
e
7439-92-1
Lead
1.0
d
7439-93-2
Lithium
2.5
f
7487-94-7
Mercury (mercuric chloride)
0.01
d
7439-98-7
Molybdenum
0.308
e
14797-55-8
Nitrate as N
100
d
14797-73-0
Perchlorate
0.0081
e
7440-28-0
Thallium
0.02
h
7440-62-2
Vanadium
0
.
1
d
Constituent Name and Groundwater
Quality Standard Notations
a
The
inorganic groundwater quality standards are based on total metal analyses for
the evaluation of human health effects.
b
A
treatment factor of 4 is applied to the Class I groundwater quality standard.
The constituent's treatment efficiency is based on the effectiveness to treat
the constituent in the groundwater at an 75% removal efficiency rate for the
constituent.
c
The
constituent meets the definition of a "carcinogen" in Section
620.110.
d
The
standard is based on beneficial use for watering livestock, per "Water
Quality Criteria", by National Academy of Sciences, incorporated by
reference in Section 620.125.
e
The
Class II standard is equal to the Class I groundwater quality standard.
f
The
standard is based on beneficial use for irrigation of crops, per "Water
Quality Criteria", by National Academy of Sciences, incorporated by
reference in Section 620.125
cial use for watering livestock, per "Water
Quality Criteria", by National Academy of Sciences, incorporated by
reference in Section 620.125.
e
The
Class II standard is equal to the Class I groundwater quality standard.
f
The
standard is based on beneficial use for irrigation of crops, per "Water
Quality Criteria", by National Academy of Sciences, incorporated by
reference in Section 620.125.
g
The
standard is based on beneficial use for watering livestock and irrigation of crops,
per "Water Quality Criteria", by National Academy of Sciences,
incorporated by reference in Section 620.125.
h
A
treatment factor of 10 is applied to the Class I groundwater quality standard.
The constituent's treatment efficiency is based on the effectiveness to treat
the constituent in the groundwater at an 90% removal efficiency rate for the
constituent.
2)         Except as provided in Section 620.450 or subsection (a)(3) or (e)
of this Section, concentrations of the following chemical constituents must not
be exceeded in Class II groundwater:
CASRN
Constituent
Standard (mg/L)
a,b
7429-90-5
Aluminum
5
c
7440-42-8
Boron
2
d
16887-00-6
Chloride
200
e
7440-50-8
Copper
0.5
c
7439-89-6
Iron
5
e
7439-96-5
Manganese
10
d
7440-02-0
Nickel
2
d
7440-14-4
Radium (combined 226+228)
5
f
7782-49-2
Selenium
0.02
d
7440-22-4
Silver
0.058
f
14808-79-8
Sulfate
400
e
TDS (total dissolved solids)
1,200
e
7440-66-6
Zinc
10
d
Constituent
Name and Groundwater Quality Standard Notations
a
The
standard units for radium (combined 226+228) is picocuries per liter (pCi/L).
b
The
inorganic groundwater quality standards are based on total metal analyses for
the evaluation of human health effects.
c
The
standard is based on beneficial use for watering livestock and irrigation of
crops, per "Water Quality Criteria", by National Academy of Sciences,
incorporated by reference in Section 620.125
dard units for radium (combined 226+228) is picocuries per liter (pCi/L).
b
The
inorganic groundwater quality standards are based on total metal analyses for
the evaluation of human health effects.
c
The
standard is based on beneficial use for watering livestock and irrigation of
crops, per "Water Quality Criteria", by National Academy of Sciences,
incorporated by reference in Section 620.125.
d
The
standard is based on beneficial use for irrigation of crops, per "Water
Quality Criteria", by National Academy of Sciences, incorporated by
reference in Section 620.125.
e
The
standard is the 95% confidence concentration stated in the Agency's "Integrated
Water Quality Report and Section 303(d) List", incorporated by reference in
Section 620.125.
f
The Class II standard is equal to the Class I groundwater
quality standard.
3)         The standard for any inorganic chemical constituent specified
in subsection (a)(2) and barium specified in subsection (a)(1) does not apply
within fill material or within the upper 10 feet of parent material under fill
material on a site not within the rural property class for which the conditions
of subsection (a)(3)(A) or (a)(3)(B) are met. For pH
,
the standard specified in subsection (d) does not apply to
groundwater within fill material below 5 feet of land surface or within the
upper 10 feet of parent material under  fill material on a site not within the
rural property class for which the conditions of subsection (a)(3)(A) or
hin the rural property class for which the conditions
of subsection (a)(3)(A) or (a)(3)(B) are met. For pH
,
the standard specified in subsection (d) does not apply to
groundwater within fill material below 5 feet of land surface or within the
upper 10 feet of parent material under  fill material on a site not within the
rural property class for which the conditions of subsection (a)(3)(A) or
(a)(3)(B) are met.
A)        Before November 25, 1991, surficial characteristics have been
altered by placing the fill material so as to impact the concentration of any
parameter (constituent or pH) specified in this subsection (a)(3), and any
on-site groundwater monitoring of the parameter is available for review by the
Agency.
B)        On November 25, 1991, surficial characteristics are in the
process of being altered by placing the fill material, in a reasonably
continuous manner to completion, so as to impact the concentration of any
parameter (constituent or pH) specified in this subsection (a)(3), and any
on-site groundwater monitoring of the parameter is available for review by the
Agency.
4)         For subsection (a)(3), the term "fill material"
means clean earthen materials, slag, ash, clean demolition debris, or similar
materials.
b)         Organic Chemical Constituents
1)         Except due to natural causes or as provided in Section 620.450
or subsection (b)(2) or (e) of this Section, concentrations of the following
organic chemical constituents must not be exceeded in Class II groundwater:
CASRN
Constituent
Standard (mg/L)
83-32-9
Acenaphthene
1.2
a
67-64-1
Acetone
3.5
b
15972-60-8
Alachlor
c
0.01
a
116-06-3
Aldicarb
0.015
a
120-12-7
Anthracene
6
a
319-84-6
alpha
-BHC
(
alpha
-benzenehexachloride)
c
0.00006
a
71-43-2
Benzene
c
0.025
a
56-55-3
Benzo(a)anthracene
d
0.0012
a
205-99-2
Benzo(b)fluoranthene
d
0.0012
a
207-08-9
Benzo(k)fluoranthene
d
0.012
a
50-32-8
Benzo(a)pyrene
d
0.002
e
65-85-0
Benzoic acid
15
b
78-93-3
2-Butanone (methyl ethyl
ketone)
2.3
b
1563-66-2
Carbofuran
0.2
a
75-15-0
116-06-3
Aldicarb
0.015
a
120-12-7
Anthracene
6
a
319-84-6
alpha
-BHC
(
alpha
-benzenehexachloride)
c
0.00006
a
71-43-2
Benzene
c
0.025
a
56-55-3
Benzo(a)anthracene
d
0.0012
a
205-99-2
Benzo(b)fluoranthene
d
0.0012
a
207-08-9
Benzo(k)fluoranthene
d
0.012
a
50-32-8
Benzo(a)pyrene
d
0.002
e
65-85-0
Benzoic acid
15
b
78-93-3
2-Butanone (methyl ethyl
ketone)
2.3
b
1563-66-2
Carbofuran
0.2
a
75-15-0
Carbon disulfide
1.9
a
56-23-5
Carbon tetrachloride
c
0.025
a
12789-03-6
Chlordane
c
0.01
a
108-90-7
Chlorobenzene
0.5
a
67-66-3
Chloroform
c
0.35
a
218-01-9
Chrysene
d
0.12
a
94-75-7
2,4-D (2,4-dichloroohenoxy
acetic acid)
0.35
a
75-99-0
Dalapon
2.0
e
53-70-3
Dibenzo(a,h)anthracene
d
0.0005
a
96-12-8
1,2-Dibromo-3-chloropropane
d
0.002
e
1918-00-9
Dicamba
0.12
b
95-50-1
o
-Dichlorobenzene (1,2-dichlorobenzene)
1.5
f
106-46-7
p
-Dichlorobenzene
(1,4-dichlorobenzene)
c
0.375
a
75-71-8
Dichlorodifluoromethane
3.9
a
75-34-3
1,1-Dichloroethane
3.9
a
107-06-2
1,2-Dichloroethane
c
0.025
a
75-35-4
1,1-Dichloroethylene
0.035
a
156-59-2
cis
-1,2-Dichloroethylene
0.2
g
156-60-5
trans
-1,2-Dichloroethylene
0.5
a
75-09-2
Dichloromethane (methylene
chloride)
d
0.025
a
78-87-5
1,2-Dichloropropane
b
0.025
a
117-81-7
Di(2-ethylhexyl)phthalate
b
0.06
e
84-66-2
Diethyl phthalate
3.1
b
84-74-2
Di-
n
-butyl phthalate
1.9
a
99-65-0
1,3-Dinitrobenzene
0.001
b
121-14-2
2,4-Dinitrotoluene
c
0.005
a
606-20-2
2,6-Dinitrotoluene
c
0.005
a
88-85-7
Dinoseb
0.07
e
123-91-1
1,4-Dioxane (
p
-dioxane)
c
0.00078
b
145-73-3
Endothall
0.1
b
72-20-8
Endrin
0.01
a
100-41-4
Ethylbenzene
c
1.0
h
106-93-4
Ethylene dibromide (1,2-dibromoethane)
c
0.0005
e
206-44-0
Fluoranthene
0.75
a
86-73-7
Fluorene
0.75
a
58-89-9
gamma
-HCH
(
gamma-
hexachlorocyclohexane, lindane)
c
0.001
a
13252-13-6
HFPO-DA (hexafluoropropylene
oxide dimer acid GenX)
0.000010
b
2691-41-0
HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)
3.9
a
76-44-8
Heptachlor
c
0.002
a
1024-57-3
Heptachlor epoxide
c
0.001
a
77-47-4
Hexachlorocyclopentadiene
0.5
e
193-39-5
Indeno(1,2,3-c,d)pyrene
d
uoranthene
0.75
a
86-73-7
Fluorene
0.75
a
58-89-9
gamma
-HCH
(
gamma-
hexachlorocyclohexane, lindane)
c
0.001
a
13252-13-6
HFPO-DA (hexafluoropropylene
oxide dimer acid GenX)
0.000010
b
2691-41-0
HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)
3.9
a
76-44-8
Heptachlor
c
0.002
a
1024-57-3
Heptachlor epoxide
c
0.001
a
77-47-4
Hexachlorocyclopentadiene
0.5
e
193-39-5
Indeno(1,2,3-c,d)pyrene
d
0.0012
a
98-82-8
Isopropylbenzene (cumene)
c
1.9
a
93-65-2
MCPP (mecoprop)
0.1
b
1634-04-4
MTBE (methyl tertiary-butyl
ether)
0.5
e
72-43-5
Methoxychlor
0.2
a
90-12-0
1-Methylnaphthalene
1.35
a
91-57-6
2-Methylnaphthalene
0.075
a
95-48-7
2-Methylphenol (
o
-cresol)
0.19
b
91-20-3
Naphthalene
0.39
a
98-95-3
Nitrobenzene
0.0077
b
1336-36-3
PCBs (polychlorinated biphenyls
as decachloro- biphenyl)
c
0.0025
a
375-73-5
PFBS (perfluorobutanesulfonic
acid)
0.002
b
355-46-4
PFHxS (perfluorohexanesulfonic
acid)
0.000010
b
375-95-1
PFNA (perfluorononanoic acid)
0.000010
b
335-67-1
PFOA (perfluorooctanoic acid)
c
0.000004
b
1763-23-1
PFOS (perfluorooctanesulfonic
acid)
c
0.000004
b
87-86-5
Pentachlorophenol
0.005
a
108-95-2
Phenol
0.1
ii
1918-02-1
Picloram
5.0
e
129-00-0
Pyrene
0.6
a
121-82-4
RDX (hexahydro-l,3,5-trinitro-l,3,5-trianzine)
0.062
b
122-34-9
Simazine
0.04
e
100-42-5
Styrene
0.5
a
118-96-7
TNT (2,4,6-trinitrotoluene)
0.039
a
93-72-1
2,4,5-TP (silvex)
0.25
a
127-18-4
Tetrachloroethylene
c
0.025
a
108-88-3
Toluene
2.5
f
8001-35-2
Toxaphene
c
0.015
a
120-82-1
1,2,4-Trichlorobenzene
0.7
e
71-55-6
1,1,1-Trichloroethane
1
a
79-00-5
1,1,2-Trichloroethane
0.05
e
79-01-6
Trichloroethylene
d
0.025
a
75-69-4
Trichlorofluoromethane
6
a
99-35-4
1,3,5-Trinitrobenzene
2.3
a
75-01-4
Vinyl chloride
d
0.01
a
1330-20-7
Xylenes
10
b
Constituent Name and Groundwater
Quality Standard Notations
a
A
treatment factor of 5 is applied to the Class I groundwater quality standard
4-Trichlorobenzene
0.7
e
71-55-6
1,1,1-Trichloroethane
1
a
79-00-5
1,1,2-Trichloroethane
0.05
e
79-01-6
Trichloroethylene
d
0.025
a
75-69-4
Trichlorofluoromethane
6
a
99-35-4
1,3,5-Trinitrobenzene
2.3
a
75-01-4
Vinyl chloride
d
0.01
a
1330-20-7
Xylenes
10
b
Constituent Name and Groundwater
Quality Standard Notations
a
A
treatment factor of 5 is applied to the Class I groundwater quality standard.
The constituent's treatment efficiency is based on the effectiveness to treat
the constituent in the groundwater at an 80% removal efficiency rate for the
constituent.
b
The
Agency's treatment efficiency determination demonstrates a treatment factor is
not applicable for the constituent.  The standard is equal to the Class I
groundwater quality standard.
c
The
constituent meets the definition of a "carcinogen" in Section
620.110.
d
The
constituent meets the definition of a "mutagen" in Section 620.110.
e
A
treatment factor of 10 is applied to the Class I groundwater quality standard.
The constituent's treatment efficiency is based on the effectiveness to treat
the constituent in the groundwater at a 90% removal efficiency rate for the
constituent.
f
A
treatment factor of 2.5 is applied to the Class I groundwater quality
standard.  The constituent's treatment efficiency is based on the effectiveness
to treat the constituent in the groundwater at a 60% removal efficiency rate
for the constituent.
g
A
treatment factor of 3 is applied to the Class I groundwater quality standard.
The constituent's treatment efficiency is based on the effectiveness to treat
the constituent in the groundwater at a 65% removal efficiency rate for the
constituent.
h
A
treatment factor of 1.5 is applied to the Class I groundwater quality
standard.  The constituent's treatment efficiency is based on the effectiveness
to treat the constituent in the groundwater at a 30% removal efficiency rate
for the constituent.
i
The standard is based on 35 Ill. Adm. Code 302.208
the constituent in the groundwater at a 65% removal efficiency rate for the
constituent.
h
A
treatment factor of 1.5 is applied to the Class I groundwater quality
standard.  The constituent's treatment efficiency is based on the effectiveness
to treat the constituent in the groundwater at a 30% removal efficiency rate
for the constituent.
i
The standard is based on 35 Ill. Adm. Code 302.208.
2)         The standards for pesticide chemical constituents specified in
subsection (b)(1) do not apply to groundwater within 10 feet of the land
surface if the concentrations of the constituents result from applying
pesticides in a manner consistent with the Federal Insecticide, Fungicide, and
Rodenticide Act (7 U.S.C. 136 et seq.) and the Illinois Pesticide Act [415 ILCS
60].
c)         Complex Organic Chemical Mixtures
1)         Concentrations of the following organic chemical constituents
must not be exceeded in Class II groundwater:
CASRN
Constituent
Standard (mg/L)
71-43-2
Benzene
a
0.025
b
Total BETX
13.525
c
Constituent Name and Groundwater
Quality Standard Notations
a
The
constituent meets the definition of a "carcinogen" in Section
620.110.
b
A
treatment factor of 5 is applied to the Class I groundwater quality standard.
The constituent's treatment efficiency is based on the effectiveness to treat
the constituent in the groundwater at an 80% removal efficiency rate for the
constituent.
c
The standard is the total combined Class II standard of
benzene, ethylbenzene, toluene, and xylenes.
2)         Atrazine
and Metabolites
Concentration of the following
chemical constituents must not be exceeded in Class II groundwater.
CASRN
Constituent
Standard (mg/L)
1912-24-9
Atrazine
0.015
a
Total Atrazine and Metabolites
0.015
6190-65-4
DEA (desethyl-atrazine)
1007-28-9
DIA (desisopropyl-atrazine)
3397-62-4
DACT (diaminochlorotriazine)
Constituent Name and Groundwater
Quality Standard Notations:
a
A treatment factor of 5 is applied to the Class I
groundwater quality standard
s must not be exceeded in Class II groundwater.
CASRN
Constituent
Standard (mg/L)
1912-24-9
Atrazine
0.015
a
Total Atrazine and Metabolites
0.015
6190-65-4
DEA (desethyl-atrazine)
1007-28-9
DIA (desisopropyl-atrazine)
3397-62-4
DACT (diaminochlorotriazine)
Constituent Name and Groundwater
Quality Standard Notations:
a
A treatment factor of 5 is applied to the Class I
groundwater quality standard.  The constituent's treatment efficiency is based
on the effectiveness to treat the constituent in the groundwater at an 80%
removal efficiency rate for the constituent.
d)         pH
Except due to
natural causes, a pH range of 6.5 - 9.0 units must not be exceeded in Class II
groundwater.
e)         No
facility that is subject to 35 Ill. Adm. Code 811 or 814 must comply with any
requirement or standard of those rules to the extent it incorporates or is
otherwise based on any of the following constituents or their standards under
this Section:
CASRN
Constituent
13252-13-6
HFPO-DA
(hexafluoropropylene oxide
dimer acid GenX)
375-73-5
PFBS
(perfluorobutanesulfonic acid)
355-46-4
PFHxS
(perfluorohexanesulfonic acid)
375-95-1
PFNA (perfluorononanoic acid)
335-67-1
PFOA (perfluorooctanoic acid)
1763-23-1
PFOS
(perfluorooctanesulfonic acid)

## 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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