35 Ill. Adm. Code 302.503
pH
Section 302
Section 302.503 pH
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.