Illinois Administrative Code
Title 35 - ENVIRONMENTAL PROTECTION
Part 611 - PRIMARY DRINKING WATER STANDARDS
Subpart B - FILTRATION AND DISINFECTION
Section 611.212 - Groundwater under Direct Influence of Surface Water
Current through Register Vol. 48, No. 38, September 20, 2024
The Agency must require a CWS supplier to demonstrate under Section 611.201 whether it uses "groundwater under the direct influence of surface water". Based on the information the supplier provides, the Agency must determine whether a PWS uses "groundwater under the direct influence of surface water". The Agency must base this determination on specific factors:
a) Physical Characteristics of the Source. Whether the source is obviously a surface water source, such as a lake or stream. Other sources possibly subject to influence from surface waters include springs, infiltration galleries, wells, or other collectors in subsurface aquifers.
b) Well Construction Characteristics and Geology with Field Evaluation
c) Any structural modifications to prevent the direct influence of surface water and eliminate the potential for Giardia lamblia cyst contamination.
d) Source Water Quality Records. Specific factors indicate that a source is under the direct influence of surface water:
e) Significant and relatively rapid shifts in water characteristics, such as turbidity, temperature, conductivity, or pH.
f) Significant and relatively rapid shifts in water characteristics, such as turbidity, temperature, conductivity, or pH, closely correlating with climatological or surface water conditions indicate surface water influence.
g) Particulate Analysis. Significant occurrence of insects or other macroorganisms, algae, or large-diameter pathogens, such as Giardia lamblia, indicates surface influence.
h) The potential for contamination by small-diameter pathogens, such as bacteria or viruses, does not alone render the source "under the direct influence of surface water".
BOARD NOTE: This Section derives from the definition of "groundwater under the direct influence of surface water" in 40 CFR 141.2; from the Preamble at 54 Fed. Reg. 27489 (June 29, 1989); and from the USEPA Guidance Manual for Filtration and Disinfection (91).