Section 303.351  Mississippi River South Central Temperature

Instead of the standards of 35 Ill. Adm. Code 302.211(e), the water temperature at representative locations in the main river of the Mississippi River in the indicated locations must not exceed the maximum limits in the following tables during more than 1% of the hours in the 12-month period ending with any month.  The water temperature at these locations must not at any time exceed the maximum limits in the following table by more than 1.7 ºC (3 ºF).

a)         In the Mississippi River from the Illinois River to Alton Lock and Dam:

b)         In the Mississippi River from Alton Lock and Dam to the Kaskaskia River:

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)