Ill. Admin. Code tit. 35 § 611.301

Current through Register Vol. 49, No. 2, January 10, 2025

Section 611.301 - Revised MCLs for Inorganic Chemical Contaminants

a) This subsection corresponds with 40 CFR 141.62(a), reserved by USEPA. This statement maintains structural consistency with USEPA rules.

b) The MCLs in the following table apply to CWSs. Except for fluoride, the MCLs also apply to NTNCWSs. The MCLs for nitrate, nitrite, and total nitrate and nitrite also apply to transient non-CWSs.

Contaminant	MCL	Units
Antimony	0.006	mg/L
Arsenic	0.010	mg/L
Asbestos	7	MFL
Barium	2	mg/L
Beryllium	0.004	mg/L
Cadmium	0.005	mg/L
Chromium	0.1	mg/L
Cyanide (as free CN^-)	0.2	mg/L
Fluoride	4.0	mg/L
Mercury	0.002	mg/L
Nitrate (as N)	10	mg/L
Nitrite (as N)	1	mg/L
Total Nitrate and Nitrite (as N)	10	mg/L
Selenium	0.05	mg/L
Thallium	0.002	mg/L

BOARD NOTE: See Section 611.300(d) for an elevated nitrate level for non-CWSs. USEPA removed and reserved the MCL for nickel on June 29, 1995, at 60 Fed. Reg. 33932, as a result of a judicial order in Nickel Development Institute v. EPA, No. 92-1407, and Specialty Steel Industry of the U.S. v. Browner, No. 92-1410 (D.C. Cir. Feb. 23 & Mar. 6, 1995), while retaining the contaminant, analytical methodology, and detection limit entries for this contaminant.

c) USEPA identifies specific treatment technologies as BAT for achieving compliance with the IOC MCLs, except for fluoride:

Contaminant	BATs
Antimony	C/F RO
Arsenic (BATs for As^V. Pre-oxidation may be required to convert As^III to As^V.)	AAL
	C/F
	IX
	LIME
	RO
	ED
	O/F (to obtain high removals, the iron to arsenic ratio must be at least 20:1)
Asbestos	C/F
	DDF
	CC
Barium	IX
	LIME
	RO
	ED
Beryllium	AA
	C/F
	IX
	LIME
	RO
Cadmium	C/F
	IX
	LIME
	RO
Chromium	C/F
	IX
	LIME (for Cr^III only)
	RO
Cyanide	IX
	RO
	ALK Cl₂
Mercury	C/F (only if influent Hg concentrations less than or equal to 10 µg/L)
	GAC
	LIME (only if influent Hg concentrations less than or equal to 10 µg/L)
	RO (only if influent Hg concentrations less than or equal to 10 µg/L)
Nickel	IX
	LIME
	RO
Nitrate	IX
	RO
	ED
Nitrite	IX
	RO
Selenium	AAL
	C/F (for Se^IV only)
	LIME
	RO
	ED
Thallium	AAL
	IX

Abbreviations
AAL	Activated alumina
ALK Cl₂	Alkaline chlorination (pH [GREATER THAN OR EQUAL TO] 8.5)
C/F	Coagulation/filtration (not BAT for a system having fewer than 500 service connections)
CC	Corrosion control
Cl₂	Oxidation (chlorine)
DDF	Direct and diatomite filtration
ED	Electrodialysis
GAC	Granular activated carbon
IX	Ion exchange
LIME	Lime softening
O/F	Oxidation/filtration
RO	Reverse osmosis
UV	Ultraviolet irradiation

d) At 40 CFR 141.62(d), USEPA identified the affordable technology, treatment technique, or other means available to systems serving 10,000 persons or fewer for achieving compliance with the MCL for arsenic:

Small System Compliance Technologies (SSCTs)¹ for Arsenic²
Small system compliance technology	Affordable for listed small system categories³
Activated alumina (centralized)	All size categories
Activated alumina (point-of-use)⁴	All size categories
Coagulation/filtration⁵	501 to 3,300 persons, 3,301 to 10,000 persons
Coagulation-assisted microfiltration	501 to 3,300 persons, 3,301 to 10,000 persons
Electrodialysis reversal⁶	501 to 3,300 persons, 3,301 to 10,000 persons
Enhanced coagulation/filtration	All size categories
Enhanced lime softening (pH >10.5)	All size categories
Ion exchange	All size categories
Lime softening⁵	501 to 3,300 persons, 3,301 to 10,000 persons
Oxidation/filtration⁷	All size categories
Reverse osmosis (centralized)⁶	501 to 3,300 persons, 3,301 to 10,000 persons
Reverse osmosis (point-of-use)⁴	All size categories

¹ Section 1412(b)(4)(E)(i) through (iii) of SDWA (42 U.S.C. 300g-1(b)(4)(E)(i) through (iii)) specifies that SSCTs must be affordable and technically feasible for a small system supplier.

² SSCTs for As^V. Pre-oxidation may be required to convert As^III to As^V.

³ SDWA specifies three categories of small system suppliers: (1) those serving 25 or more, but fewer than 501 persons, (2) those serving more than 500 but fewer than 3,301 persons, and (3) those serving more than 3,300 but fewer than 10,001 persons. 42 U.S.C. 300g-1(b)(4)(E)(ii).

⁴ When a supplier uses POU or POE devices for compliance, the supplier must provide programs to ensure proper long-term operation, maintenance, and monitoring to ensure adequate performance.

⁵ A supplier will not likely install this technology solely for arsenic removal. This technology may require pH adjustment to optimal range to obtain high removals.

⁶ This technology rejects a large volume of water and may not be appropriate for areas where water quantity is an issue.

⁷ To obtain high removals using this technology, the iron to arsenic ratio must be at least 20:1.

Ill. Admin. Code tit. 35, § 611.301

Amended at 37 Ill. Reg. 1978, effective February 4, 2013

Amended at 42 Ill. Reg. 1140, effective 1/4/2018

Amended at 47 Ill. Reg. 16486, effective 11/2/2023

BOARD NOTE: This Section derives from 40 CFR 141.62.