1. a) One of the following four classes of groundwater under Sections 620.210 through 620.240:

   1. 1) Class I: Potable Resource Groundwater;
   2. 2) Class II: General Resource Groundwater;
   3. 3) Class III: Special Resource Groundwater; or
   4. 4) Class IV: Other Groundwater;
2. b) A groundwater management zone established under Section 620.250; or
3. c) A groundwater management zone established under 35 Ill. Adm. Code 740.530. See Section 620.250(h)-(j).

All groundwaters of the State are designated as:

(Source: Amended at 49 Ill. Reg. 4488, effective March 28, 2025)