Ill. Admin. Code tit. 35, § 406.107
In addition to the other requirements of Subtitle D, mine discharge effluent must not contain settleable solids, floating debris, visible oil, grease, scum, or sludge solids. Color, odor, and turbidity must be reduced below obvious levels.
(Source: Amended at 43 Ill. Reg. 11620, effective September 25, 2019)