1. a) A person must not cause or allow the concentration of the following constituents in any effluent to exceed the following levels, subject to the averaging rules in Section 304.104(a).

   1. b) Discharges of hexavalent chromium are subject to the averaging rule of Section 304.104 modified as follows: monthly averages must not exceed 0.1 mg/L; daily composites must not exceed 0.3 mg/L; and, grab samples must not exceed 1.0 mg/L.
   2. c) Oil may be analytically separated into polar and nonpolar components. If separated, neither of the components may exceed 15 mg/L (i.e. 15 mg/L polar materials and 15 mg/L nonpolar materials).
   3. d) Unless otherwise indicated, concentrations refer to the total amount of the constituent present in all phases, whether solid, suspended or dissolved, elemental or combined, including all oxidation states. Where constituents are commonly measured as other than total, the word "total" is inserted for clarity.

   4. e) The following table is provided for cross-referencing purposes:

      CONSTITUENT	SECTIONS
      Ammonia nitrogen	304.301, 304.122
      Bacteria	304.121
      Biochemical Oxygen Demand	304.120
      Deoxygenating Wastes	304.120
      Mercury	304.126
      Nitrogen, ammonia	304.301, 304.122
      pH	304.125
      Phosphorus	304.123

   CONSTITUENT		CONCENTRATION mg/L
   Arsenic		0.25
   Barium		2.0
   Cadmium		0.15
   Chromium (hexavalent)		0.1
   Chromium (total)		1.0
   Copper		0.5
   Cyanide		0.10
   Fluoride		15.0
   Iron (total)		2.0
   Lead		0.2
   Manganese		1.0
   Nickel		1.0
   Oils (hexane soluble or equivalent)		15.0
   Phenols		0.3
   Silver		0.1
   Zinc		1.0
   Total Suspended Solids (From sources other than those covered by Section 304.120)		15.0

(Source: Amended at 47 Ill. Reg. 4601, effective March 23, 2023)