Illinois Administrative Code › Title 35 - ENVIRONMENTAL PROTECTION › Part 611 - PRIMARY DRINKING WATER STANDARDS › Subpart Z - ENHANCED TREATMENT FOR CRYPTOSPORIDIUM › Section 611.1001 - Source Water Monitoring Requirements: Source Water Monitoring

Current through Register Vol. 48, No. 28, July 12, 2024
a) Initial Round of
				Source Water Monitoring. A supplier must conduct the following monitoring on
				the schedule in subsection (c), unless it meets the monitoring exemption
				criteria in subsection (d).
1) A filtered
				system supplier serving 10,000 or more people must sample its source water for
				Cryptosporidium, E. coli, and turbidity at least monthly for 24
				months.
2) An unfiltered system
				supplier serving 10,000 or more people must sample its source water for
				Cryptosporidium at least monthly for 24 months.
3) Smaller System Suppliers Monitoring for E.
				coli
A) A filtered system supplier serving
				fewer than 10,000 people must sample its source water for E. coli at least once
				every two weeks for 12 months.
B) A
				filtered system supplier serving fewer than 10,000 people may avoid E. coli
				monitoring if the system notifies the Agency that it will monitor for
				Cryptosporidium as described in subsection (a)(4). The system must notify the
				Agency no later than three months prior to the date before which the system is
				otherwise required to start E. coli monitoring under subsection (c).
4) Smaller System Suppliers
				Monitoring for Cryptosporidium. A filtered system supplier serving fewer than
				10,000 people must sample its source water for Cryptosporidium at least twice
				per month for 12 months or at least monthly for 24 months if it meets any of
				the conditions set forth in subsections (a)(4)(A) through (a)(4)(C), subject to
				the limitations of subsection (a)(4)(D), based on monitoring conducted under
				subsection (a)(3).
A) For a supplier using a
				lake or reservoir source, the annual mean E. coli concentration is greater than
				10 E. coli/100 mL.
B) For a
				supplier using a flowing stream source, the annual mean E. coli concentration
				is greater than 50 E. coli/100 mL.
C) The supplier does not conduct E. coli
				monitoring as described in subsection (a)(3).
D) A supplier using groundwater under the
				direct influence of surface water must comply with the requirements of
				subsection (a)(4) based on the E. coli level that applies to the nearest
				surface water body. If no surface water body is nearby, the system must comply
				based on the requirements that apply to a supplier using a lake or reservoir
				source.
5) For a
				filtered system supplier serving fewer than 10,000 people, the Agency may issue
				a SEP approving monitoring for an indicator other than E. coli under subsection
				(a)(3). The Agency may also issue a SEP approving an alternative to the E. coli
				concentration in subsection (a)(4)(A), (a)(4)(B), or (a)(4)(D) to trigger
				Cryptosporidium monitoring. This approval by the Agency must be provided to the
				supplier in writing, and it must include the basis for the Agency's
				determination that the alternative indicator or trigger level will provide a
				more accurate identification of whether a system will exceed the Bin 1
				Cryptosporidium level set forth in Section
				611.1010.
6) An unfiltered system supplier serving
				fewer than 10,000 people must sample its source water for Cryptosporidium at
				least twice per month for 12 months or at least monthly for 24
				months.
7) A supplier may sample
				more frequently than required by this Section if the sampling frequency is
				evenly spaced throughout the monitoring period.