Section 302.502  Dissolved Oxygen

Dissolved oxygen must not be less than 90% of saturation, except due to natural causes, in the Open Waters of Lake Michigan as defined at Section 302.501.  The other waters of the Lake Michigan Basin must not be less than 6.0 mg/L during at least 16 hours of any 24 hour period, nor less than 5.0 mg/L at any time.

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