Section 302.408  Temperature

a)         For the South Fork of the South Branch of the Chicago River (Bubbly Creek), the temperature must not exceed 34 ºC (93 ºF) more than 5% of the time, or 37.8 ºC (100 ºF) at any time.

b)         The temperature standards in subsections (c) through (i) will become applicable beginning July 1, 2018.

c)         There must not be any abnormal temperature changes that may adversely affect aquatic life unless caused by natural conditions.

d)         The normal daily and seasonal temperature fluctuations that existed before the addition of heat due to other than natural causes must be maintained.

e)         The maximum temperature rise above natural temperatures must never exceed 2.8 °C (5 °F).

f)         Water temperature at representative locations in the main river must never exceed the maximum limits in the applicable table in subsections (g), (h) and (i), during more than one percent of the hours in the 12-month period ending with any month.  The water temperature must not exceed the maximum limits in the applicable table that follows by more than 1.7 °C (3.0 °F).

g)         Water temperature in the Chicago Area Waterway System Aquatic Life Use A waters listed in 35 Ill. Adm. Code 303.235 must not exceed the limits in the following table in compliance with subsection (f):

h)         Water temperature in the Chicago Area Waterway System and Brandon Pool Aquatic Life Use B waters listed in 35 Ill. Adm. Code 303.240 must not exceed the limits in the following table in compliance with subsection (f):

i)          Water temperature for the Upper Dresden Island Pool Aquatic Life Use waters, as defined in 35 Ill. Adm. Code 303.230, must not exceed the limits in the following table in compliance with subsection (f):

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