Section 302.404  pH

pH must be within the range of 6.5 to 9.0 except due to natural causes, except for the South Fork of the South Branch of the Chicago River (Bubbly Creek), for which pH must be within the range of 6.0 to 9.0 except due to natural causes.

(Source:  Amended at 47 Ill. Reg. 4437, effective March 23, 2023)