pH must be within the range of 7.0 to 9.0, except due to natural causes, in the Open Waters of Lake Michigan as defined at Section 302.501. Other waters of the Basin must be within the range of 6.5 to 9.0 except due to natural causes.
Ill. Admin. Code tit. 35, § 302.503
Amended at 23 Ill. Reg. 11249, effective August 26, 1999