Section 611.300  State-Only MCLs for Inorganic Chemical Contaminants

a)         The State-only MCLs listed in subsection (b) for inorganic chemical contaminants (IOCs) are additional State requirements.  The State-only MCLs apply only to CWS suppliers.  The supplier must determine compliance with the State-only MCLs for inorganic chemicals under Section 611.612.

b)         State-only MCLs for IOCs

c)         This subsection corresponds with 40 CFR 141.11(c), marked as reserved by USEPA.  This statement maintains structural parity with the federal rules.

d)         Nitrate

A non-CWS may exceed the MCL for nitrate under certain circumstances:

1)         The nitrate level must not exceed 20 mg/L;

2)         The water must not be available for consumption by children under six months of age;

3)         The NCWS supplier complies with the public notification requirements under Section 611.909, including continuous posting that the nitrate level exceeds 10 mg/L with the potential health effects of exposure;

4)         The supplier annually notifies local public health authorities and the Department of Public Health of nitrate levels exceeding 10 mg/L; and

5)         No adverse public health effects result.

BOARD NOTE:  This subsection (d) derives from 40 CFR 141.11(d).  The Department of Public Health regulations may impose a nitrate limitation requirement at 77 Ill. Adm. Code 900.50.

e)         Supplementary conditions apply to the MCLs for iron and manganese in subsection (b):

1)         A CWS supplier serving a population of 1,000 or fewer or 300 service connections or fewer are exempt from the standards for iron and manganese.

2)         The Agency may issue a SEP allowing iron and manganese in excess of the MCL if sequestration proves effective on an experimental basis.  If sequestration is not effective, the supplier must provide positive iron or manganese reduction treatment, as applicable.  A supplier may try experimental use a sequestering agent only if the Agency approves in a SEP.

BOARD NOTE:  This subsection (e) is an additional State requirement.

(Source:  Amended at 47 Ill. Reg. 16486, effective November 2, 2023)